Patent Application
20100132295
The present invention is directed to exterior wall cladding containing composite building materials and a siding clip. More specifically, the present invention is directed to siding containing foamed composite building materials. Also, the present invention is directed to siding having foamed composite building materials that are coated with a high performance urethane/acrylic coating.
Conventional building products, particularly for use in siding, trim, railing, decking and fencing, have included natural wood. Natural wood has been used traditionally for its availability and relatively low cost (although wood siding and trim may be a more expensive product when maintenance costs are considered). However, drawbacks to natural wood exist. For example, the quality of available natural wood has diminished over time. Natural wood requires chemical treatment (e.g., surface coatings) to extend service life in most exterior applications. Some treatment processes have been deemed environmentally unsound and have been prohibited in some jurisdictions, further diminishing the use of natural wood. In addition, natural wood has the drawback that it splinters, rots, discolors and/or requires significant maintenance when used in applications exposed to the outdoors, such as siding, e.g., home siding.
Composite materials have been used as an alternative to natural wood because they are generally weather resistant and relatively maintenance free. Composite materials also have the ability to provide a wood-like appearance and texture. Composite materials are materials that have reinforcing material, typically fibers, embedded in a matrix material, typically a polymeric material. Polymeric materials known in the art include high or low-density olefin thermoplastic, vinyl-based thermoplastic polymers and newly created agrigrown thermoplastics. The particular polymer used in the composite depends on the properties desired in the final product. Typical fibers for use in building materials may be synthetic or natural fibers. The reinforcing fibers provide the final product with desired and improved properties, such as reduced thermal coefficient of expansion, strength and/or lower cost. In some applications, glass fibers may be used.
Composite materials are typically formed by extrusion. In this method, composite materials are formed by melting and extruding a matrix material. Typically, the matrix material is a polymeric material. In the extrusion method, an extruder melts the matrix material, while mixing the matrix material with the reinforcing fiber. The polymer becomes impregnated with the reinforcing fibers. In addition to the reinforcing fibers, additives may be introduced into the mixture. Suitable additives include stabilizers, antioxidants, UV absorbers, fillers and extenders, pigments, process aids and lubricants, impact modifiers, bactericides and other materials that enhance physical and/or chemical properties, as well as processing. A blowing agent or gas may also be introduced into the mixture. While the mixture is heated inside the extruder, the blowing agent thermally decomposes, releasing a gas, such as nitrogen or carbon dioxide, throughout the melted matrix material. After the matrix material, fiber and other additives are mixed, the melted mixture exits the extruder through a die. The mixture exits the die at a relatively high pressure. Once the mixture exits the die, the pressure exerted on the mixture is reduced to atmospheric pressure. The gases produced by the blowing agent expand under the reduced pressure and the matrix material solidifies, trapping the gas bubbles inside the composite material. The gas bubbles form voids in the composite, providing desirable properties to the final product. For example, the voids reduce the overall density and weight of the finished product. This process, called foaming, is becoming commonplace due to its cost advantage, as well as providing a weight-to-volume advantage. Although most composites are still produced without blowing agent, the melt process is substantially the same.
One type of composite building material known in the art is a cellulose fiber reinforced cement composite disclosed in U.S. Pat. No. 6,777,103 to Merkley et al. (the '103 patent). This concrete-based composite material is being used on sidewalls, trim and roofing applications. Although the cement composite material is resistant to permanent water and termite damage when it is properly coated and installed, the cement composite suffers from several drawbacks. One disadvantage of the cement composite of the '103 patent is that the material is susceptible to cracking and chipping during transit, warehousing, job site storage, handling and installation. Another undesirable characteristic of the cement composite is that exterior products formed from the cement composite are subject to degradation of mechanical properties in geographic regions that experience freezing and thawing conditions. Another objectionable feature of the cement composite is that the density of the material is high, leading to heavy building components susceptible to sagging and/or breaking. The product is unforgiving of improper installation, and without proper sealing and drainage, it can be eroded by moisture penetration. Further the high density also increases labor requirements—e.g., a 3-man installation crew is common with fiber cement. Also, there may be concern about the carcinogenic silica dust released when the material is field cut—respirators may be required, although enforcement of this requirement may be difficult.
Another type of composite building material known in the art is a recycled wood and polyethylene composite disclosed in U.S. Pat. No. 6,527,532 to Muller et al. (the '532 patent). The material disclosed by the '532 patent is a wood-thermoplastic composite material generally having 35-60 wt % polyethylene matrix incorporating 65-40 wt % wood component. The wood component may be introduced in chip, fiber or flour form. The wood-thermoplastic composite, as disclosed in the '532 patent, has several drawbacks. One disadvantage is that the final product has a high density, increasing the shipping and handling demands. A further objectionable feature is a tendency to sag when used as a semi-load bearing material as in seating or decking. Additionally, the pigments and cellulosic additives in the wood-thermoplastic composite material, as disclosed in the '532 patent, run and/or fade when exposed to outdoor conditions. The wood fiber itself is prone to color shift when exposed to ordinary weathering forces, usually shifting to a weathered grey appearance. Another undesirable feature is that the wood-thermoplastic composite material, as disclosed in the '532 patent, absorbs and retains significantly high heat levels when exposed to sunlight due to the excessive absorption of infrared light. Another undesirable feature of the wood-thermoplastic composite material is that the cellulosic components therein contain nutrients that can support the growth of mold and/or mildew. Low stain, scratch and mar resistance are also undesirable features of these compositions.
Another type of composite building material known in the art is a foamed polymer-fiber composite disclosed, for example, in U.S. Pat. No. 6,344,268 to Stucky et al. (the '268 patent). The material disclosed by the '268 patent is a foamed polymer material reinforced with wood fibers. The composites include about 35-75 wt % polymeric resin and about 25-65 wt % fiber. The specific gravity of the material is less than about 1.25 g/cc and the coefficient of expansion is about 2.4×10−5/in/in/° F. The polymer-fiber composite has several drawbacks. The polymer-fiber composite disclosed in the '268 patent has essentially the same undesirable characteristics of the above composite disclosed by the '532 patent, although it is more fire resistant and somewhat more stable to sunlight. Another disadvantage of the polymer-fiber composite disclosed in the '268 patent is that the material experiences relatively rapid degradation of mechanical properties when exposed to outdoor conditions.
Another siding product with great popularity is vinyl siding. This product is generally, by comparison, thin and is more a paint replacement as there is little, if any, structural integrity. Heat distortion may result from excessive heat build and the resulting strains plus its expansion and contraction due to heat load from below freezing to well over 140 degrees (insolation) causes stresses. These expansion/contraction stresses may result in distortion difficulties and poor aesthetics on the wall. Vinyl siding is relatively low in cost and price, is easy to install and does not require frequent painting. It is a low maintenance product and has a large representation among the sidewall alternatives. Its popularity may be dropping, however, due to aesthetics and perceived lack of structural integrity.
Exterior building products, such as siding, are exposed to the full solar radiation spectrum of light including damaging UV and IR wave lengths and to cycles of heating and cooling upon exposure to the sun. UV and heat sensitive substrates such as vinyl, polyolefins, styrenics (including ABS, ASA), polycarbonates, polyesters and other material are susceptible to UV light and heat degradation over long periods of time. Thus, methods for absorption of ultraviolet energy, transmission, absorption and reflectance of various frequencies of visible light (pigmentary color) and as much reflection of near infrared energy may be required (reduction of solar heating).
For siding applications, a further need exists to provide an advantageous interlocking mechanism to secure siding panels to each other and to provide an advantageous mechanism to secure the siding to a wall, e.g., a structural wall.
It is therefore desirable to develop a composite building material, and a method for making a composite building material, that overcomes the disadvantages of the prior art.
According to an example embodiment of the present invention, a siding system includes a plurality of panels each having a front portion adapted to be exposed when the panel is installed as siding, a back portion adapted to face a surface covered by the siding when the panel is installed as siding, a channel formed in the back portion adjacent a downwardly extending projection of the back portion. The siding system also includes a clip configured to engage an upper portion of one of the panels to secure the panel against a building surface, the clip having a back plate configured to receive a fastener therethrough, and an upwardly extending projection that, when the clip engages the upper portion of the panel, is configured to extend into the channel of another one of the panels such that the extension of the upwardly extending projection into the channel constrains a bottom portion of the another one of the panels the via contact with the downwardly extending projection of the another one of the panels.
The upper portion of each panel may have a plurality of spaced-apart notches.
The clip may include a first arm extending away from the base plate, the first arm configured to be received in one of the spaced-apart notches.
The first arm may be configured to constrain lateral expansion and contraction of a panel when the first arm is received in the notch.
The clip may include a second arm configured to be received in one of the spaced-apart notches, the clip being configured to maintain two of the panels at a predetermined spacing to form a butt joint.
The first arm may be part of a set of arms configured to be received by corresponding spaced-apart notches of a first one of the two panels of the butt joint, and the second arm is part of a set of arms configured to be received by corresponding spaced-apart notches of a second one of the two panels of the butt joint.
The spacing between the notches may be constant.
The siding system may also include a starter strip having a back panel configured to receive a fastener therethrough, and an upper projection configured to be received by one of the channels of the panels.
Each of the panels may have a rounded projection and a groove, the rounded projection configured to form a detent with the groove of a panel of an adjacent course of panels.
The clip may be bent from a single piece of metal.
According to an example embodiment of the present invention, a siding panel includes a front portion adapted to be exposed away from a surface covered by the siding panel, a back portion adapted to face a surface covered by the siding panel, a channel formed in the back portion adjacent a downwardly extending projection of the back portion, and upper portion having a plurality of spaced-apart notches extending through the front and back portions.
The back portion may have a plurality of expansion relief grooves.
The expansion relief grooves may be substantially vertical when the panel is installed.
According to an example embodiment of the present invention, a siding clip includes a back plate having an aperture configured to receive a fastener therethrough, a first arm extending outwardly from the back plate, a second arm extending outwardly from the back plate, an outer plate substantially parallel to the back plate and supported by the first arm, the outer plate extending upwardly to form an upward projection extending above the height of the first arm, and an outer plate substantially parallel to the back plate and supported by the second arm, the outer plate extending upwardly to form an upward projection extending above the height of the second arm.
The outer plate supported by the first arm and the outer plate supported by the second arm may be the same.
According to an example embodiment of the present invention, a siding panel includes an upper portion having an upper male locking element and an upper female locking element, a bottom portion having a bottom male locking element and a bottom female locking element, and a front face that faces outward and is exposed when the siding panel is installed. The upper male locking element and the upper female locking element are configured to engage, respectively, corresponding bottom female and male locking elements of like panels, and the bottom male locking element and the bottom female locking element are configured to engage, respectively, corresponding upper female and male locking elements of like panels.
The panel may be formed from a composite building material having a foamed substrate having a foamed inner core and a dense integral skin, wherein the foamed substrate includes a polymer matrix and a reinforcing filler, and a urethane/acrylic coating applied to the foamed substrate at the front face of the siding panel, wherein the coating includes an IR-reflective pigment, wherein the urethane/acrylic coating is chemically and/or physically bound to the substrate.
According to an example embodiment of the present invention, a siding panel includes a front face, a back face, two side edges, an upper portion including an upper channel adjacent to an upper protrusion, a bottom portion including a bottom channel adjacent to a bottom protrusion. The upper channel is configured to receive the bottom protrusion of other like panels, the upper protrusion is configured to be received by the bottom channel of the other like panels, the bottom channel is configured to receive the top protrusion of the other like panels, and the bottom protrusion is configured to be received by the top channel of the other like panels.
The upper channel may be disposed between the top protrusion and the back face, and the bottom channel may be disposed between the bottom protrusion and the front face.
The upper portion may further include a nailing flange disposed between the upper channel and the back face, the nailing flange extending upwardly beyond the upper protrusion to provide a nailing surface.
According to an example embodiment of the present invention, a siding set includes a plurality of siding panels, each panel including an upper portion including an upper channel, the upper channel being adjacent to both a first upper protrusion and a second upper protrusion, and a bottom portion including a bottom channel, the bottom channel being adjacent to a bottom protrusion. The upper channel is configured to receive the bottom protrusion of each of the panels, the upper protrusion is configured to be received by the bottom channel of each of the other panels, the bottom channel is configured to receive the top protrusion of each of the other panels, and the bottom protrusion is configured to be received by the top channel of each of the other panels. The set also includes a siding clip having a nailing flange and configured to be disposed between the upper channel and the lower protrusion of two respective panels when the lower protrusion is received by the upper channel, the siding clip extending a distance beneath the bottom of the lower protrusion.
The siding clip may further include a first clip channel that is configured to receive the bottom protrusion of each of the plurality of panels.
The siding clip may further include a second clip channel configured to receive the second upper protrusion of any of the plurality of panels, the first clip channel being disposed in the upper channel of the panel when the upper protrusion is received by the second clip channel.
The nailing flange may have a pre-formed nail hole.
The siding clip may be formed from galvanized steel, stainless steel, or any other appropriate material.
According to an example embodiment of the present invention, a siding set includes a plurality of siding panels, each panel including an upper portion including an upper channel, the upper channel being adjacent to both a first upper protrusion and a second upper protrusion, a front face that faces outward and is exposed when the siding panel is installed, and a bottom portion including a bottom channel, the bottom channel being adjacent to a bottom protrusion. The upper channel is configured to receive the bottom protrusion of each of the panels, the upper protrusion is configured to be received by the bottom channel of each of the other panels, the bottom channel is configured to receive the top protrusion of each of the other panels, and the bottom protrusion is configured to be received by the top channel of each of the other panels. The set also includes a siding clip having a nailing flange, a first clip channel that is configured to receive the bottom protrusion of each of the plurality of panels, a second clip channel configured to receive the second upper protrusion of any of the plurality of panels, the first clip channel being disposed in the upper channel of the panel when the upper protrusion is received by the second clip channel.
The panel may be formed from a composite building material having a foamed substrate having a foamed inner core and a dense integral skin, wherein the foamed substrate includes a polymer matrix and a reinforcing filler, and a urethane/acrylic coating applied to the foamed substrate at the front face of the siding panel, wherein the coating includes an IR-reflective pigment, wherein the urethane/acrylic coating is chemically and/or physically bound to the substrate.
The present invention provides a siding panel including an upper portion having an upper male locking element and an upper female locking element, a bottom portion having a bottom male locking element and a bottom female locking element, and a front face that faces outwardly and is exposed when the siding panel is installed. The upper male locking element and the upper female locking element engage, respectively, corresponding bottom female and male locking elements of like panels. The bottom male locking element and the bottom female locking element engage, respectively, corresponding upper female and male locking elements of like panels. The panel is formed from a composite building material having a foamed substrate having a foamed inner core and a dense integral skin, where the foamed substrate includes a polymer matrix and a reinforcing filler, and preferably a urethane/acrylic coating or a decorative laminate film applied to the foamed substrate at the front face of the siding panel, where the coating and/or film includes an IR-reflective pigment, and where the urethane/acrylic coating or laminate film is chemically and/or physically bound to the substrate. Another technique replaces some the integral skin which is removed by milling and replacing that skin with a backprinted film having color and image laminated to the machined foamed product in a fashion that provides a infinite pattern selection. The image film can be coated with any UV protecting film used to prevent substrate deterioration due to UV exposure. Stable backprints utilize back printed inks which reflect the sun's near-infrared energy, thus reducing the sidewall temperature. Solar reflectance is critical to retard those degradation reactions that create color and physical property deterioration over time.
According to some examples, the polymer matrix is PVC. According to some examples, the reinforcing filler is a non-cellulosic material. According to other examples, the reinforcing filler includes calcium carbonate, talc, or other high-aspect low-abrasion stable minerals. In accordance with another example, the reinforcing filler is a flax or other agrifiber. According to some examples, the reinforcing filler or fiber is present in the foamed composite in an amount of about 15 to about 50 parts per hundred relative to the PVC. According to other examples, the reinforcing filler is present in the foamed composite in an amount of about 18 to about 25 parts per hundred relative to the PVC. According to some examples, the urethane/acrylic coating further includes aluminum oxide. In some examples, the aluminum oxide is present in the coating in an amount of about 1% to about 4% by weight. In some examples, the IR-reflective pigment is an IR-reflective mixed metal oxide. In some examples, the IR-reflective pigment is present in the coating in an amount of about 10% to about 20% by weight. In some examples, the front surface of the siding panel is embossed, then sealed. In accordance with some examples, the front (reveal surface) is coated and then embossed. Further, in accordance with some examples a pigmented color film is coated with Urethane/Acrylic clear coat specially formulated for exterior use or is coated or laminated to other films such as PVF (Tedlar), PVDF (Kynar), ASA (Luran) Acrylic (Lucite) or other clear weatherable clear overlays. These examples all allow for the use of solar reflective pigments incorporated into color stable weather resistant polymer matrices. In some examples a skeletal wood grain printed image is laminated to the pigmented solid colored film and provides further image possibilities such as woodgrains, stone, or artistic renderings. In yet another example a printed or solid colored film using IR-reflective inks is coated with urethane or other weather resistant clear coats and then laminated to the siding substrate.
The present invention provides a siding panel having a front face, a back face, two side edges, an upper portion including an upper channel adjacent to an upper protrusion, and a bottom portion including a bottom channel adjacent to a bottom protrusion. The upper channel is able to receive the bottom protrusion of other like panels, and the upper protrusion is able to be received by the bottom channel of the other like panels. The bottom channel is able to receive the top protrusion of the other like panels, and the bottom protrusion is able to be received by the top channel of the other like panels. According to some examples, the upper channel is disposed between the top protrusion and the back face, and the bottom channel is disposed between the bottom protrusion and the front face. According to some examples, the upper portion further includes a nailing flange disposed between the upper channel and the back face, the nailing flange extending upwardly beyond the upper protrusion to provide a nailing surface.
Another example embodiment provides a siding in simple plank form having alternative surfacing technologies. These panels are face nailed at the installed top and a scrim tape with pressure sensitive adhesive is carefully positioned on the panel. The release tape may have a printed reticule for lining the courses. Once nailed the release tape is pulled away and palm pressure may be used to glue the courses together. A tongue-and-groove end match may be provided and the butts firmly joined and sealed using a vinyl adhesive. Also, the overlap portion may be back beveled to provide level coursing and good contact surface for the adhesive. These planks can be any gauge between ½″ and 1¼″ thickness and normal siding widths.
The present invention provides a siding set having a plurality of siding panels, each panel including an upper portion including an upper channel, the upper channel being adjacent to both a first upper protrusion and a second upper protrusion, and a bottom portion including a bottom channel, the bottom channel being adjacent to a bottom protrusion. The upper channel is able to receive the bottom protrusion of each of the other panels, the upper protrusion is able to be received by the bottom channel of each of the other panels, the bottom channel is able to receive the top protrusion of each of the other panels, and the bottom protrusion is able to be received by the top channel of each of the other panels. The set may also include a siding clip having a nailing flange and able to be disposed between the upper channel and the lower protrusion of two respective panels when the lower protrusion is received by the upper channel, the siding clip extending a distance beneath the bottom of the lower protrusion. According to some examples, the siding clip further includes a first clip channel that is configured to receive the bottom protrusion of each of the plurality of panels. According to some examples, the siding clip further includes a second clip channel able to receive the second upper protrusion of each of the plurality of panels, the first clip channel being disposed in the upper channel of the panel when the upper protrusion is received by the second clip channel. According to some examples, the nailing flange has a pre-formed nail hole. According to some examples, the siding clip is formed from stainless steel. According to some examples, the nailing flange is formed from galvanized steel, which may be particularly suitable from a strength standpoint. According to some examples, the siding clip is formed from plastic, e.g., propylene. According to other examples, the siding clip is formed from marine aluminum. The nailing clip may be advantageous as it allows fasteners to be “shot,” e.g., by a pneumatic nail gun, when installing the siding without substantial risk of damaging the siding panels.
The present invention provides a process for preparing a foamed (cellular) composite building product comprising the steps of: providing a foamable mixture comprising a polymeric matrix material, a filler, a processing aid, one or more lubricants, a thermal stabilizer, and a blowing agent; extruding the molten foamable mixture; foaming said foamable mixture to form a foamed composite substrate; optionally embossing the substrate; and coating the substrate with a polyurethane/acrylic coating to form the composite building product, wherein the polyurethane/acrylic coating is chemically or physically bound (or “keyed”) to the foamed composite substrate.
The present invention includes as an embodiment, a method for making a composite building material involving the step of providing a matrix material precursor, a reinforcing filler material, a blowing agent, a stabilizer, one or more processing aids, and, optionally, other additives. The matrix material precursor, the reinforcing filler material, the stabilizer and process aid(s) are mixed to form an extrusion dry blend compound. The matrix material precursor typically comprises poly (vinyl chloride) resin. The reinforcing filler is preferably a nanoparticle sized calcium carbonate material that is surface treated with a polar compatibilizer. Alternatively, a fine vegetable fiber such as flax, jute, hemp, and/or sisal can be used to reduce the COE (thermal coefficient of expansion). Additionally, inorganic fiber from glass, fly ash, or other minerals can be used but are not preferred due to abrasion of the extrusion surfaces. The blowing agent comprises a material that thermally decomposes and releases gas. The stabilizer comprises a metal ligand and is used to prevent degradation of the polymer under the high temperature of processing and to prevent further degradation at the slightly elevated service temperatures found in the outdoor environment. The extrusion mixture is heated to a temperature sufficient to volatilize any moisture or other volatile materials and then is heated to a melt temperature. This is all accomplished in a tightly controlled extruder. The melted composition is expressed at high pressure through a die to produce an extruded product and is sized and cooled at a controlled rate.
In one embodiment, the method and product according to the present invention produces a lightweight substrate product having the preferred physical and chemical properties. However, it is particularly preferred that the substrate be coated with a urethane/acrylic coating, particularly for applications in which the composite building material is used outdoors. Thus, in preferred embodiments of the present invention the method for producing the composite building material involves the step(s) of coating the substrate with a urethane/acrylic coating. In certain embodiments, the coating of the substrate with a urethane/acrylic coating is performed in-line as a part of the fabrication of the composite building material, rather than as a remote or separate step. In preferred embodiments of the invention the urethane/acrylic coating comprises one or more pigments and is cured using a UV curing step.
In particularly preferred embodiments, the urethane/acrylic coating may be coated onto the substrate and cured using an ultraviolet radiation curing system. The UV curing of the coating is initiated by a photoinitiator that absorbs distinct energies of UV light. The preferred coatings also contain IR reflective pigments and, optionally, one or more UV protective agents. The UV protection agents, IR-reflective pigments, and other optional coating components may absorb or reflect frequencies of UV radiation. Thus, in the past, the use of such coating components in conjunction with a UV curing systems would have been problematic, resulting in incomplete curing or low adhesion to the substrate. However, in the preferred coating compositions of the present invention, these problems have been overcome by the selection of the IR-reflective pigment, UV protection agent(s), photoinitiator and the UV light source which allow for an efficient curing of the UV cured urethane/acrylic coating. The coating components and the UV light source are selected in combination to allow for the transmission of a frequency of UV light from the emission source through the entire thickness of the coating.
Example embodiments of the present invention may utilize printed imaging and profile lamination. Further, composites according to example embodiments of the present invention may or may not have reinforcing fibers. Coextrusion of capstocks may also be applicable to example embodiments of the present invention.
An advantage of the product according to the present invention is that the final product is resistant to weathering. In preferred embodiments, the substrate, having been extruded, is then embossed with a woodgrain or other appealing pattern and then coated with a high performance cross-linked polyurethane/acrylic coating. The coating preferably contains UV protection agents, pigments having good IR reflectance and low solar temperature gain and additives that enhance scratch and mar resistance and provide an anti-slip surface. The color of the composite according to the present invention resists fading when exposed to rain water and sunlight. The substrate generally contains a similar coloration as the coating, but does not require the enhancement and thus is far less expensive.
An additional advantage of the method and product according to the present invention is that the final product maintains a lower surface temperature when exposed to sunlight, making the material desirable as a siding material.
An additional advantage of the method and product according to the present invention is that the materials for fabrication are comparatively inexpensive and provide an alternative to natural wood and/or composite materials present in the building materials marketplace.
An additional advantage of the method and product according to the present invention is that the composite material has a high tensile strength, flexural modulus and impact resistance, making the composite material resistant to chipping, flaking and/or breaking. In addition, the material has an increased stability.
An additional advantage of the method and product according to the present invention is that the composite material has a low water absorption rate. A lower absorption rate makes the composite lighter in weight and more uniform in expansion properties. Lighter weight and uniformity in expansion properties results in a product that is easier to install and does not produce gaps from non-uniform expansion and contraction. Also, the lack of water absorption prevents microbial growth.
An additional advantage of the method and product according to the present invention is that the composite material is resistant to insect and termite damage not only due to low moisture absorption but to the lack of nutrients in the composition. An additional advantage of the method and product according to the present invention is that the composite material is resistant to bacterial and fungal growth.
An additional advantage of the method and product according to the present invention is that the composite material is resistant to fire. In preferred embodiments using PVC as the matrix material, the resulting composite building material has a high ignition resistance and is self-extinguishing.
An additional advantage of the method and product according to the present invention is that the composite material has a similar look and texture as natural wood, making it suitable to replace existing wood or other composite building materials used in, for example, fencing, dock, decking, siding, trim, and railing applications.
An advantage of the siding according to the present invention is that the siding panels may be securely fitted to a base structure and easy to install.
An additional advantage of the siding according to the present invention is that the siding may be stronger, more durable, and less prone to buckling than other siding. As a result the siding may have a longer lifespan than other siding.
Other features and advantages of the present invention will be apparent from the following more detailed description of the preferred embodiment, taken in conjunction with the accompanying drawings which illustrate, by way of example, the principles of the invention.
Wherever possible, the same reference numbers will be used throughout the drawings to refer to the same or like parts.
The composite of the present invention includes a desirable combination of properties useful for building materials. The desirable properties of the composite material include low density, high tensile strength, high flexural modulus, high impact strength, low water absorption, and good resistance to weathering. In particular, the composite material according to the present invention has a density of less than about 1.0 g/cc, preferably less than about 0.7 g/cc. The density may be measured by any suitable test known in the art, including ASTM standard D792. The composite material according to the present invention preferably has a strength (i.e., tensile strength) of greater than about 2600 psi., preferably greater than about 2800 psi. The tensile strength may be measured by any suitable test known in the art, including ASTM standard D638. The composite material according to the present invention also preferably has a flexural modulus of greater than about 400 kpsi., preferably greater than about 230 kpsi. The flexural modulus may be measured by any suitable test known in the art, including ASTM standard D790. The composite material according to the present invention also preferably has impact strength of greater than about 150 inch-lbs., preferably greater than about 160 inch-lbs. The impact strength may be measured by any suitable test known in the art, including ASTM standard D2794. The composite material according to the present invention preferably has water absorption rate of less than about 1%, preferably less than about 0.5%. The water absorption may be measured by any suitable test known in the art, including ASTM standard D570. The composite material and it's urethane acrylic coating according to the present invention preferably has weathering rate (i.e., color stability) of less than 3.0 delta E, preferably less than about 2.0 delta E. The color stability may be measured by any suitable test known in the art, including ASTM standard G-26, 12 Month Florida Exposure and/or 2500 hour artificial weathering using a UVA-340 lamp.
The mixture of ingredients for extrusion includes a polymeric matrix material. Suitable polymeric matrix materials may include, but are not limited to, poly (vinyl chloride) (PVC), chlorinated PVC, polyethylene, polypropylene, polystyrene, styreneacrylonitrile, acrylonitrile butadiene styrene, acrylic/styrene/acrylonitrile block terpolymer (ASA), polycarbonates, polyurethane, and co-polymers or combinations thereof. The composition may include one or more polymeric matrix materials.
In preferred embodiments the polymeric matrix material is PVC resin. The PVC resin preferably provides at least a portion of the matrix of the composite material. Any PVC resin suitable for forming a cellular structure may be used. The PVC resin is preferably a low average molecular weight material that provides an inherent viscosity of about 0.75 to about 0.83, preferably about 0.78 to about 0.8 Inherent viscosity may be measured by any suitable means known in the art, including viscosity measured by ASTM standard D1243. The process preferably uses a lower average molecular weight material in order to provide lower processing temperatures during extrusion. Because the process utilizes a lower processing temperature, the stabilization and long term weathering of the finished composite is increased.
When, as is preferred, PVC is the polymeric matrix material, a stabilizer may be used to inhibit the dehydrochlorination of the PVC and prevent burning of the PVC during the processing in the extruder. A stabilizer is a material added to the extrusion mixture to impart heat and light stability and/or lower the decomposition temperature of the blowing agent. Suitable stabilizers for use in the present invention include tin mercaptides. A suitable stabilizer includes, but is not limited to, a combination of tin mercaptide and di-butyl tin maleate, wherein a free maleic acid may also be present. Although a preferred stabilizer includes a combination of tin mercaptide and di-butyl tin maleate, any stabilizer that lowers the decomposition temperature of the blowing agent and/or provides free radicals for cross linking with the coating may be used. This provides for a fusion bonded surface to substrate adhesion. Suitable stabilizers are available from Rohm and Haas under the trade names TM-181, TM-182, TM-183C, TM-186, TM-281, TM 283, TM-286SP, TM-440, TM-599, TM-694, TM-697, TM-900, TM-950, TM-1830, S-1000, S-1201, and S-1401.
Lubricants preferably are added to the extrusion mixture for extrusion in order to provide internal lubrication within the polymer mixture and to provide external lubrication for metal release from the extruder during extrusion. The lubricant for internal lubrication is added to the extrusion blend in order to control fusion and allow slip between the polymer chains. The lubricant for external lubrication provides a wetting of the melt surface lubrication and easier release at the melt/metal interface at the surface of the extruder. The mixture may include one or a combination of lubricants that provide internal and external lubrication. Any material useful as internal and/or external lubricants may be used in the mixture for extrusion. Suitable lubricants for external lubrication include, but are not limited to, paraffin wax and oxidized polyethylene. Suitable lubricants for internal lubrication include, but are not limited to, carboxylic acid salts (e.g., calcium stearate).
The reinforcing filler(s) provides improved strength to the finished composite material 100 according to the present invention. The reinforcing filler preferably has a high surface area to weight that provides reinforcement to the polymer matrix. The reinforcing filler may be any type of organic, inorganic, or natural fiber or powder, or a mixture thereof, suitable for providing the desired structural qualities and durability. Examples of suitable fillers that may be used in the composition include calcium carbonate, talc, calcium sulfate (e.g., gypsum), magnesium oxide, diatomaceous earth, mica, glass fibers, silica, wollastonite and/or mineral wool. Although cellulosic materials may be used in one preferred embodiment, care must be taken to see that the cellulose content is high and the pitch, lignin, asphaltenes and other oils and sugars are not present. This fiber is used only for reinforcement. Flax and other sized fibers from the bast family suit this application. In other preferred embodiments, the filler is an inorganic, non-fibrous material such as calcium carbonate, calcium sulfate, talc, etc., and is most preferably calcium carbonate.
In a particularly preferred embodiment, when the reinforcing filler comprises an organic flax material, the surface of the reinforcing fiber is treated with polar compatibilizer. Polar compatibilizers include material suitable to treat the surface of the reinforcing filler. Preferred compatibilizers include ionic surfactants, non-ionic surfactants, polyethene oxides, etc. Thus, in particularly preferred embodiments, reinforcing filler comprises a flax which is surface treated with a polar compatibilizer.
The mixture of ingredients for extrusion preferably includes a high loading of the reinforcing filler material(s). In the formulation according to the invention, the formulation may comprise 5-50 parts per hundred of the filler material(s), preferably 15-50 parts per hundred of the filler material(s), and more preferably 18-25 parts per hundred of the filler material(s). Preferably, the filler is selected to be a material that fills the matrix and has a low cost. Additionally, the filler may provide assistance in catalytic decomposition of the blowing agent. In order to provide greater cell nucleation in the matrix material, the filler material preferably has a high surface area—for example the filler may be ground to a fine particle size. Suitable particle sizes include, but are not limited from about 0.3 microns. Further it is preferred that the filler be of a high purity. Suitable purities include, but are not limited to, greater than about 99.5%. The use of flax is between 15-25% and the calcium carbonate about 20%.
Processing aids are preferably added to the mixture for extrusion in order to provide increased cell wall strength and good cell nucleation. The use of the processing aids allows the use of lubricant for external lubrication in order to prevent sticking to the extruder. Suitable materials for use as processing aids include a combination of a high molecular weight acrylic resin with a low molecular weight acrylic resin. The low molecular weight acrylic resin component primarily provides lubrication, while the high molecular weight acrylic resin provides some lubrication, but primarily assists in cell formation. The combination of processing aids provides a lubricated product that forms a desirable cellular structure, including high cell wall strength and good cell nucleation. High cell wall strength and good cell nucleation provides a finished composite having increased rigidity and increased weatherability. The increased weatherability is a result of the high molecular weight acrylic resin and is more light-stable than PVC resin alone. While the processing aids have been described as a combination of a high molecular weight acrylic resin and a low molecular weight acrylic resin, the processing aids added can be any processing aid or combination of processing aids that provide lubrication to the process, provide good cell formation and provide a light stable material. Suitable acrylic processing aids are commercially available under the trade names Paraloid K-415, Paraloid K-400, Paraloid K-175, Paraloid K-128N, Paraloid K-125, Paraloid K-120, Paraloid K-120N, Paraloid 120ND, and Paraloid K-130D from Rohm & Haas; and PA-20, PA-40, and PA-50 from Kaneka Corporation.
Titanium dioxide is preferably added to the mixture for extrusion in order to provide a background tint for the substrate pigments. The titanium dioxide helps to provide opacity to the coated finished composite.
A blowing agent is preferably added to the mixture for extrusion in order to provide porosity to the finished composite material. The blowing agent is preferably a combination of materials that include a carrier, a catalyst, an endothermic component and an exothermic component. The endothermic component and the exothermic component both contribute to the formation of the gaseous voids 110 and the cellular structure in the composite material 100. The blowing agent combination, including the carrier, catalyst, the endothermic component and the exothermic component, is ground to a fine particle size. Suitable particle sizes for blowing agent components include, but are not limited to, 1-5 micron diameter. The endothermic component may be added to the mixture during the extruding step. The carrier is any carrier that melts easily in the extruder and disperses the combination of blowing agent components throughout the mixture for extrusion. A suitable carrier for use in the blowing agent includes, but is not limited to, ethylene-vinyl-acetate copolymer. The catalyst is a material that assists in decomposition of the exothermic component. The catalyst is any material that assists in the decomposition of the exothermic component during heating. The endothermic component preferably creates an endothermic reaction when it thermally decomposes to provide temperature control of the system. When the endothermic component thermally decomposes, gases, such as carbon dioxide and/or water, are emitted and distributed throughout the extruded composite. The gases contribute to the formation of the cellular structure of the composite material 100. The endothermic component also provides alkalinity to the mixture, neutralizing undesirable acid components, such as HCl, which may contribute to degradation of the final composite material. A suitable endothermic component includes, but is not limited to, sodium bicarbonate. The exothermic component is a material that thermally decomposes in the extruder during the extrusion process and forms cells of gas within the finished composite. When the exothermic component decomposes, gases are dispersed into the resin matrix. The gas released by the exothermic component may be any gas that is capable of forming cells in the resin matrix and does not degrade the resin matrix. The gas released may include nitrogen or carbon dioxide. Suitable exothermic components include chemicals that contain decomposable groups such as azo, N-nitroso, carbonate, carbonamide, hetero-cyclic nitrogen containing surfonyl hydrazide groups. One suitable exothermic component includes, but is not limited to, azodicarbonamide.
Pigments which do not bleed and have appropriate light stability are preferably used to tint the substrate to a color relatively close to the coating. Pigments should disperse and flow well in the melt stream.
Table 1 includes formulations according to the present invention. PPH, as described in Table 1, are parts by weight per 100 parts by weight of PVC resin.
Although the above has been shown as a preferred combination of ingredients, the mixture for extrusion may also include additional additives for improvement of physical or chemical properties.
Once the ingredients have been mixed and the mixture for extrusion has been packaged, the mixture is extruded in an extrusion step 240. Extrusion takes place by heating the extruder screws to a temperature sufficient to fuse and melt the matrix material. Temperatures suitable for extrusion include temperatures of about 340° F. to about 425° F. The extruder mixes the material as it is heated. Any additional ingredients not added during the mixing step 210 may be added to the extruder. Although all of the ingredients may be blended into the mixture during the mixing step 210, one or more of the ingredients may be added during processing directly into the extruder. For example, the blowing agent, the recycled material, the stabilizer, the pigments and/or other ingredients may be provided directly into the extruder to be mixed with the other ingredients. In one embodiment of the invention, the endothermic component of the blowing agent is added directly to the extruder during extrusion.
The endothermic component of the blowing agent thermally decomposes inside the extruder in an endothermic reaction. The endothermic reaction of the blowing agent catalyst reduces the heat resulting from the exothermic decomposition of the exothermic component of the blowing agent, providing temperature control to the decomposition reaction of the exothermic component. The mixture is sheared between screws inside the extruder and is heated to the temperature of fusion. The fusion of the powder mixture results in a melt, which is extruded through a die under pressure. Suitable temperatures for fusion for the mixture include temperatures from about 340° F. to about 425° F. The temperature of the screws is monitored to control the melt temperature. Excessive temperature rise causes a burning and/or destruction of the material. Insufficient temperature rise results in a lack of melting and large forces on the extruder. In addition to melt temperature, the temperature of the screw helps control the decomposition of the blowing agent. While the mixture is heated inside the extruder, the endothermic component and exothermic component of the blowing agent thermally decomposes, releasing a gas, such as nitrogen or carbon dioxide, throughout the melted matrix material (i.e., the melt). Simultaneously, the endothermic component of the blowing agent decomposes releasing gases, such as carbon dioxide and water vapor, which helps cool the exothermic reaction of the exothermic component. After the mixture is melted and substantially uniform, the melt is expelled from the extruder through a die. The mixture exits the die at a relatively high pressure and temperature. The material leaving the die is generally greater than about 350° F.
The die has a geometry that provides increasing compression as the material exits the extruder. The die includes an internal die mandrel that channels the melt and provides the desired geometry to the composite part. The internal die mandrel also provides the product with a wall thickness. The geometry of the die depends on the shape of the composite component design. The die may be any geometry that is suitable for extrusion. For example, the die may be configured to provide a composite having a cross-section in accord with the siding panel cross sections disclosed herein. The length of the material may be any length and is only limited by the desired application and the capacity of the extruder and/or production facilities. The invention utilizes the application of a highly modified Celuka process. This process utilizes a die that extrudes through a slit having net shape dimension. Through control of die temperature a hard skin emerges from the die and all foaming occurs inward. Because of this, the physical properties of the product are substantially improved compared to the processes where foaming occurs outward and the outer surfaces are low density and soft.
At the completion of the extrusion step 230, the mixture exits the die. Once the material is through the die, the pressure exerted on the mixture is reduced to atmospheric pressure. The gases produced by the blowing agent expand under the reduced pressure and the matrix material solidifies, trapping the gas bubbles inside the composite material. The gas bubbles form voids in the composite. The voids form a closed cellular structure that provides desirable properties to the final product. As the resin matrix solidifies, the voids form a cellular structure made up of a plurality of cells. The cells are defined by cell walls formed from the resin matrix. The structure of the present invention produces a large number of cells having strong cell walls. The large number of cells and the high strength of the cell walls result in a finished composite having desirable mechanical properties. The void space within the cells provides the composite material with a lower density and compressive strength relief. The lower density provides a material that is easier to install and less expensive to transport. The compressive strength relief provides sufficient localized yield to permit screwing and/or nailing during installation without damage to the surrounding material. The cellular structure provides the composite with structural stiffness.
After the extruding step, the material is sized and cooled at a controlled rate in step 240. As the material exits the die, the material is fed to one or more calibrators. Calibrators are devices provided at or near the die exit that have at least one surface having a smooth texture, temperature control and means for holding the extrudate. The calibrators provide the finished product with desired geometry, while holding and providing controlled cooling of the material. The calibrators preferably use vacuum to hold the extrudate against the calibrator surface. As the material is extruded, the extrudate is slid across the calibrator providing the extrudate with the desired surface finish.
The calibrators also provide controlled cooling of the composite material. The material leaving the die is generally greater than about 350° F. The cooling rate is controlled in order to slow and/or halt the decomposition of the blowing agent at the surface. The slowing and/or halting of the decomposition at the surface provides desirable surface characteristics, including a substantially smooth continuous surface, while simultaneously allowing expansion across the thickness of the material. The composite material is permitted to expand in the direction extending from the calibrator surface. In one embodiment of the invention, the calibrators form a cross-section according to any of the siding panel cross sections described herein, and each of the edges of the cross-section includes a calibrator. In this embodiment, the edges form the surfaces and the expansion takes place inwardly toward the center of the material. Expansion, with respect to the size and controlled cool step 240 means expansion of the gaseous bubbles inside the composite material. The larger the area, the greater the amount of expansion. Because the calibrators cool the surface of the composite, the thermal decomposition of the blowing agent is slowed or stopped, the matrix is solidified and the surface is rendered smooth. Therefore, the surface contains few if any gaseous bubbles. However, the greater the distance from the calibrator, the greater the amount of expansion takes place and the greater the number and size of the gaseous bubbles. This process results in the composite material having a dense (i.e., substantially un-foamed) integral skin and a less dense, foamed (cellular) core. Where the thickness of the composite material is relatively large, the calibrators may be set farther apart, allowing a greater amount of expansion. Alternatively, where the thickness of the material is relatively small, the calibrators may be more closely together and reduce the amount of expansion of the material. Greater thickness of material leads to a greater number and a larger size of gaseous voids in the center of the material than lesser thickness of material.
The calibrators are preferably provided with a temperature gradient to assist in gradual cooling of the material. In one embodiment of the invention, the calibrator closest to the die exit is set to from about 110° F. to about 140° F. The temperature of the surface of the calibrator is varied so that the temperature gradually decreases as the extrudate slides across the calibrator from the die exit. Once the composite material has cooled sufficiently to solidify the resin matrix, the composite is subject to a final cooling. The final cooling generally halts the residual decomposition of the blowing agent and/or expansion within the material. The final cooling may take place using any cooling method known in the art, including spraying or immersing the composite with water, preferably chilled.
Once the composite material has been cooled, the material is then, optionally, reheated on the surface to about 220 degrees using infra red heat. The heated product then passes through a two-roll hydraulic embosser having either one or two engraved rolls which deboss an aestethetically pleasing image onto the surface. The surface temperature is tightly controlled to provide the necessary plasticity to deform the surface and to prevent rebound under use temperature. The thickness of the deformed portion of the composite material includes thickness from about 1.5 thousandths of an inch to about 50 thousandths of an inch. The embossing may be confined to outwardly facing, exposed faces of the siding panel, or may be applied to additional surfaces.
Following optional embossing, the finished product is preferably coated with a thin urethane/acrylic coating. Preferably the coating has a thickness of about 0.5 to about 3.0 thousandths of an inch. In many embodiments, conventional spray guns may be used to apply the coating. The siding panel formed from the composite building material may be coated on only the surfaces that are exposed to the environment, i.e., outer surfaces, including, e.g., an embossed outer face, or additional surfaces may be coated. The embossed surface may have a thicker coating layer, for example about 1.0 to about 3.0 thousandths of an inch, and preferably about 2.0 to about 2.5 thousandths of an inch, than the coating thickness on other surfaces, which may be about 1.0 thousandths of an inch thick.
In some embodiments of the invention, a suitable urethane/acrylic coating is a commercial product produced by Valspar under the trade name of Valthane. Another suitable coating is Polane produced by Sherwin Williams. The polymeric backbones of these products are the same (urethane/acrylic) and the free radical generation as well as catalysis is similar.
In particularly preferred embodiments, the urethane/acrylic coating is physically and/or chemically “keyed′” or bound, to the surface of the substrate. The term keyed as used herein refers to a process by which the adhesion of the coating to the substrate is improved. This may be accomplished by the selection of a suitable solvent for the application of the coating which dissolves a thin layer of the substrate. When the solvent is removed, a thin interlayer comprised of comingled substrate material and coating material may be formed. Additionally or alternatively, heat generated during the curing of the applied coating may facilitate the formation such a thin interlayer of comingled substrate material and coating material. Additionally or alternatively, the adhesion of the coating to the substrate may be accomplished by the addition of a chemical agent to the substrate that can cross-link with the coating material. Suitable materials that can be added to the substrate for cross-linking to the coating include substance comprising a maleic group, or other chemical moiety that may react by a free radicals mechanism for cross linking with a component in the coating. In other embodiments, the substrate may be pre-treated prior to the application of the coating. Such pre-treatment includes pre-heating the surfaces of the substrate to be coated prior to the application of the coating. The surface of the substrate may be heated to a temperature above the glass transition temperature for the matrix polymer. Additionally or alternatively, the surfaces of the substrate to be coated may be pre-treated with a solvent. In certain preferred embodiments, the coating is both chemically and physically keyed to the surface of the substrate.
In one embodiment, the urethane/acrylic coating is applied using suitable solvents. For this embodiment, an important part of this process involves the selection of the solvents and diluents used in the coatings. Some solvation of the substrate surface is preferred for improved adhesion of the coating to the substrate. Particularly, solvents in the ketone family functions well as diluents for the coating, and as solvents for the vinyl surface. Preferred solvents include, but are not limited to, methyl ethyl ketone, methyl isobutyl ketone, methyl amyl ketone and the like, and mixtures thereof. Upon evaporation of the solvent the coating intimately impregnated into the surface of the substrate. The solvent may be evaporated in part under ambient conditions, typically followed by exposure to elevated temperatures.
The coating is cured and the solvent is evaporated under elevated temperatures, for example by using an oven. The oven preferably is maintained at a temperature of about 160° F. to about 180° F. In addition to evaporating any remaining solvent, the elevated temperature may activate the free radical catalyst for curing the coating.
In another embodiment of the invention, the urethane/acrylic coating may be coated onto the substrate and cured using an ultraviolet radiation (UV) curing system. This embodiment has the advantage that the use of volatile organic solvents may be minimized or eliminated. Thus, this embodiment has the advantages of being environmentally friendly and of reducing or eliminating the cost of solvent recovery. One or more of the reactive monomers provide the solvent-like properties and an appropriate viscosity for spray application of the coating.
In particularly preferred UV cured urethane/acrylic coatings, the coatings are based upon the use of difunctional aliphatic urethane oligomers. The reacted oligomer(s) constitutes a backbone of the coating an has the following general structure:
Preferred coatings may comprise a mixture of oligomers and monomers including alkoxylated acrylic monomer, acrylate monomer, highly functional monomer, and aliphatic urethane acrylate, which are commercially available for example from Sartomer. Other commercially available coatings may be appropriate for use in the present invention, such as Laromer UA 9048 (solvent-free urethane acrylate thinned with DPGDA). To adjust the processing viscosity of the urethane diacrylate oligomer, it can be mixed with other acrylic resins as well as monomers such as dipropyleneglycol diacrylate (DPGDA), tripropylene glycol diacrylate (TPGDA) and the like, or mixtures thereof. These monomers may also be used as solvents for the other coating components.
The UV curing of the coating is initiated by a photoinitiator that absorbs distinct energies of UV light, typically between 200-450 nm, and generates free radicals, which in turn initiate polymerization. When using a UV curing system, the selection of pigments and other coating additives may be performed to ensure that the pigment and other additives do not strongly absorb UV radiation at the same energy as the photoinitiator, such that action of the photoinitiator is impaired. When using the UV-cured coating, free radicals must be generated by specific wavelengths of ultraviolet energy acting on a free radical initiator dispersed within the coating. Since the preferred coating composition contains many interfering fillers, pigments and other additives, both the type of initiator as well as its response to UV light becomes an important part of the system. UV radiation of the proper frequency must reach the interface between the substrate and coating in order to obtain a complete curing of the coating and to promote adequate adhesion of the coating to the substrate.
The photoinitiator may be any appropriate material that generates free radicals upon exposure to UV light, and includes, for example, benzylic ketones and derivatives thereof, and preferably are benzophenones and derivatives thereof. Other preferred properties of the photoinitiator are that it be liquid borne with no VOC generation and that it not detract from long term weathering of the product. Appropriate photoinitiators include Esacure photoinitiators (for example, Esacure KTO 46), available from Lamberti and Lucirin TPO available from BASF. Also, bisaryl phosphine oxide (BAPO) type photoinitiators which are activated by longer wavelength UV light in the near visible region above about 430 nm may be appropriate. BAPO type photoinitiators are commercially available such as Irgacure 819, Irgacure 1800, Irgacure 1850, and the like. Preferably the photoinitiator is present in the coating material at an amount of from about 0.5 to about 10% by weight. In certain embodiments, a synergist may be added to the coating that facilitates the free radical generation of the photoinitiator. Synergists may include tertiary amines, acylated tertiary amines and alkoxylated acrylate monomers. In some cases, unactivated photoiniator may act as a UV absorber for the applied coating which enhances weathering.
The preferred coating compositions of the present invention have a break (or “window”) in absorption/reflectance at wavelengths between 380 and 450 nm. This transmission window allows for the UV light within that wavelength to penetrate the coating and initiate the curing reaction. The exact position of this “window” may be adjusted with changes in pigments and other additives will influence the upper or lower bounds of the transmission window. In formulating the coatings that contain the oligomers, pigments, and other additives (UV-protectant, gloss reducers, scratch and mar additives) requires attention to the desired transmission window. To this end, use of spectrophotometric measurements of the entire coating system may be useful.
In preferred embodiments, the photoinitiator is selected which has a peak response to UV light in the transmission window of the coating and the UV source emits strongly in the same region of the UV spectrum. Thus, in preferred embodiments, the source of the UV light emits strongly in the region of about 380 nm to about 450 nm. This is also the preferred region of the UV spectrum to which the photoinitiator is sensitive. The photoinitiator is distributed uniformly through the coating, therefore the UV light photons must get through the coating mixture to the photoinitiator molecules located at the adhesion interface between the substrate and coating.
The UV lamp(s) consists of a quartz tube typically containing a small quantity of mercury. The preferred bulbs used in this invention are powered by microwave. The microwave energy vaporizes the mercury and when the bulb reaches operating temperature the vapor becomes plasma and emits characteristic wavelengths of UV light as well as some visible light. These lamps generate a tremendous number of photons which are needed for penetration of the UV light to the bonding interface.
The emission spectra two type UV bulbs are provided in
The number of bulbs and type of bulbs are manipulated for the rate of coating as well as limiting heat generation. Also significant is the effective irradiance or UV radiation reaching the coated product. Rate, distance and reflectors alter the irradiance and are manipulated for peak performance.
Since plasma often reaches 20,000 degrees F., the quartz tube of the UV bulbs heats and radiates infra red energy. It is important that the heat not reach the substrate and cause surface decomposition as most plastics will degrade quickly under high energy IR (heat) buildup. Thus, it may be important to limit the infra red emission through the use of heat absorbing reflectors and air cooled bulbs. Without the use of these elements, the generated heat may burn the substrate. The use of a chilled grid between the coated substrate and the lamp may also be needed at lower coating rates. The use of infrared reflective pigments that reflect substantial amounts of infra red energy may assists the coated substrate to withstand heat generated by the UV lamp.
In preferred embodiments, the UV-curable urethane/acrylic coating is applied to provide a coating thickness ranging from about 0.0005 to 0.003 inches. This range of film thickness generally provides optimum performance and provides the opportunity to use very intense ultraviolet light to penetrate the coating and provide enough energy at the substrate to cure the coating at the interface between the coating and substrate. This also promotes adhesion of the coating to the substrate. Multiple coats having this thickness may be applied, with curing between each coat.
The use of a UV coating system has the further advantage of reducing manufacturing space and increasing productivity. Typical cure times may be less than a second, allowing for higher line speeds. Thus, the use of a UV curing system is well suited for use in a process in which the substrate is coated with the urethane/acrylic coating as part of the same process for making the substrate. For example, the substrate may be coated immediately following embossing, followed by a radiation curing step. As the use of solvents may be minimized in this embodiment, the inclusion of one or more chemical agents in the substrate, coating or both that facilitate cross-linking of the substrate with the coating is particularly preferred. In certain embodiments, the surface of the substrate may be treated in a manner to facilitate physical keying of the coating to the substrate the surface prior, or concurrently with, the coating and radiation curing. For example, the surface of the substrate may be pre-heated or pre-treated with a solvent.
The coating is preferably enhanced with pigments selected to provide exterior weathering and low solar heat gain. In certain embodiments, UV absorbers are added that greatly enhance ultraviolet light stability. Particulate alumina deglossing agents are added to control surface gloss while enhancing scratch and mar resistance. The alumina may be added in an amount of about 1% to about 4% by weight. Specifically, alumina nanoparticle additives are commercially available from Byk Chemie as the Nanobyk additives, including Nanobyk-3602, Nanobyk-3610 and Nanobyk 3650.
Preferred pigments for use in the coating have a low solar gain. Such pigments reflect rather than absorb infrared light. This results in a relative cooling effect as compared to other pigments. The lower solar heating of the material has many potential benefits, such as less expansion and contraction, less product degradation and improved comfort levels for materials that may contact the skin (for example, decking materials underfoot). The pigment(s) may be present in the coating in an amount of about 10% to about 20% by weight. Suitable pigments typically are fine ground mixed metal oxides and are commercially available, for example Ferro Corporation's Geode Cool Colors and Eclipse pigments.
When the pigment is used in a coating that is to be cured using a UV curing system, it is preferably selected to allow sufficient transmission of the required frequencies of UV radiation for activation of the free radical initiator throughout the depth of the coating. Thus, particularly preferred pigments for use in the present coatings have both a low solar gain (high IR reflectivity) and are substantially transparent to UV radiation in the near or mid UV spectrum. More specifically, the pigment should be substantially transparent to the frequency of UV light that is used to activate the photoinitiator. Suitable pigments are commercially available, for example Ferro Corporation's Cool Colors and Eclipse pigments, and particularly colors 10364(brown), V-9416(yellow), V-13810(red), or any appropriate commercially available white pigment, and the like.
The pigments may be dispersed in the coating composition using high energy liquid dispersators such as Cowles or Hockmeyer mixers. In preferred embodiments, the pigments are dispersed in a reactive urethane/acrylic precursor oligomer and are supplied in liquid form, preferably as a concentrate for later addition to the coating composition. This limits VOC's, which is environmentally important. It is often useful to use small additions of dispersing aid and suspension aids in preparing the dispersion of the pigments in the oligomer or coating composition.
Although the composite building materials of the present invention are utilized in siding applications, these materials may be used for, but are not limited to, decking, railing, fascia, roof shingles, floor tiles, paneling, door and window trim, outdoor furniture, fencing, playground equipment, and/or docks.
The shape of the composite material of the present invention is not limited to the specific geometries described herein. The composite material may be any geometry appropriate for siding applications that can be extruded, sized and cooled according to the method of the present invention. The shapes may include complex shapes, such as, e.g., siding accessories.
An additional advantage of the method and product according to the present invention is that the composite material is resistant to fire. In preferred embodiments using PVC as the matrix material and calcium carbonate as the reinforcing filler, the resulting composite building material has a high ignition resistance and is self-extinguishing. In preferred embodiments the composite building material has a Flame Spread Index (FSI) less than about 50, and preferably less than about 25. The FSI is measured according to the procedures outlined in ASTM E 84-06.
The upper protrusion 510a, being adjacent to the upper channel 515a, forms a side wall of the upper channel 515a. Likewise, the bottom protrusion 530b, being adjacent to the bottom channel 535b, forms a side wall of the bottom channel 535b. It should be appreciated, however, that according to other examples the upper channel 515a may be spaced apart from the upper protrusion 510a and/or the bottom channel 535b may be spaced apart from the bottom protrusion 535b. Moreover, it should be appreciated that, according to other examples, the upper portion and/or the lower portion may have more than one protrusion and/or channel.
The upper protrusion 510a and the bottom protrusion 530b are tapered, as their cross sectional areas decrease as they progress upwardly or downwardly, respectively, away from a centerline of the siding panel 500a, 500b. The upper channel 515a and the bottom channel 535b taper, as their cross sectional areas increase as they progress away from the centerline of the siding panel 500a, 500b. In this regard, the upper protrusion 510a and the bottom protrusion 530b taper in a manner that corresponds to the taper of the bottom channel 535b and the upper channel 515a, respectively. This allows the siding panels 500a, 500b to be easily positioned and securely interlocked, as there is initially substantial clearance between the respective protrusions and channels upon initial insertion/alignment, but the clearance dissipates as the siding panels are brought closer together. In this regard, the dimensions of the respective protrusions and channels may be selected so as to provide a hard stop between the outer ends of the protrusions and the bottoms of the respective channels or to have the side walls of the protrusions to interfere with the side walls of the respective channels, prior to contact between the outer ends of the protrusion and the channel bottoms. The protrusions and respective channels may also be dimensioned to closely match, whereby the ends of the protrusions contact the bottoms of the respective channels when the side walls meet. It should be appreciated that, according to other examples, the protrusions and/or channels are not tapered. According to other examples, the protrusion and/or channel profiles are curved or tapered to a point, i.e., triangular.
The upper protrusion 510, upper channel 515, bottom protrusion 530, and bottom channel 535 span the length of the siding panel 500. However, it should be appreciated that, according to other examples, the upper protrusion 510, upper channel 515, bottom protrusion 530, and/or bottom channel 535 may span less than the entire length of the siding panel or may span intermittent lengths along the expanse of the siding panel.
Each siding panel 500, 500a, 500b includes a second upper protrusion forming a nailing flange 550 that extends upwardly beyond the upper protrusion to allow space to drive a nail through the nailing flange 550 to secure the siding panel 500 to a base structure. Although the nailing flange 550 is adjacent to both the back surface 545 and the upper channel 515, it should be appreciated that according to other examples, the nailing flange may be spaced apart from the back surface 545 and/or the upper channel 515.
The siding clip 565 may be formed by bending a piece of flat stock, e.g. galvanized steel, into the illustrated shape, optionally after stamping the pre-formed nail holes.
Siding panels 1500a and 1500b have the same features as each other and share many features with the siding panels 500, 500a, 500b described above. Siding panels 1500a and 1500b differ slightly from siding panels 500, 500a, 500b in that the dimensions of the channels and protrusions have been adjusted in order to accommodate the siding clip 565. The siding panels 1500a and 1500b also have inset portions 600, 605 that compensate for the thickness of the siding clip 565 by providing an inset from the back face where the clip is located, thereby allowing the back face 1545a, 1545b to remain flush with the surface of the base structure to which the siding is mounted. In this regard, the inset portions 600, 605 are inset by the distance 610, which is approximately the same distance as the thickness of the clip along the first extension 580 of the clip 565. Although the inset portions 600, 605 span the entire length of the siding panels, it should be appreciated that, according to other examples, the inset portions may be localized where the clips are to be located, i.e., at set intervals. Moreover, it should be appreciated that at least a part of the inset portion 600 may be inset by a distance less than the distance 610, as the clip is less thick in this area. However, it may be advantageous to maintain some clearance between the nailing flange and the siding panel at the location where the fasteners are to be driven, as the fastener heads, e.g., nail heads, may require some amount of clearance.
Referring, e.g., to
Referring to
The starter strip 2100 also includes a lip or upward extension or projection, 2115. The lip 2115 is adapted, e.g., sized and shaped, to be received in the channels 2035 of the panels 2005 of the initial, e.g., bottom, course of siding panels. The lip 2115 mates with the channels 2035 in a manner analogous to that shown in
Although the starter strip 2100 extends continuously along the majority of the length of the initial course of panels 2005, it should be understood that multiple, shorter, starter strips may be provided. Similarly, although the lip 2115 extends continuously along the length of the starter strip 2100, it should be understood that the lip 2115 may be extend less than the length of the starter strip and/or may be discontinuous.
After the starter strip is installed, one or more panels 2005 of the first course of panels may be mated to the starter strip 2100 by positioning the panel 2005 such that the upwardly extending lip 2115 of the starter strip 2100 is able to clear the downwardly extending lip or projection 2030 of the panel 2005 as the panel 2005 is moved toward the base structure 3000 to which the starter strip 2100 is fastened. In this manner the lip 2115 is positioned adjacent the wall 2032 of the panel 2005. At this point, the panel 2005 may be lowered such that the lip 2115 of the starter strip 2100 engages or mates with the channel 2035. When the panel 2005 is in this lowered, mated position, the lower portion of the panel 2005 is constrained against outward movement away from the base structure 3000 by contact between the projection 2030 of the panel 2005 and the lip 2115 of the starter strip 2100.
In order to limit rotation of the panel 2005 about the interface with the lip 2115 of the starter strip, the wall 2032 extends downwardly beyond the interface with the lip 2115 to the portion which has an inward lip or projection 2033 that extends from the wall 2032 toward the base structure 3000 to which the starter strip is fastened. As such, contact between the portion of the wall 2032 that extends below the interface and an outer face of the starter clip may restrain rotation. Likewise, when projections of the various clips and butt-joint clips described herein are engaged with the channels 2035 of the panels 2005, the wall 2032 may analogously contact an outer face of such clips to restrain rotation.
Since the panels 2005 are easily and quickly positionable such that one of the upward lips or projections of the various clips, butt-joint clips, or starter strips engages the channel 2035 of the panel 2005, and since the panels are prevented from rotating to fall away from the base structure 3000, e.g., exterior wall, a single installer may easily and quickly install and fasten the panels 2005 and associated clips and butt-joint clips.
After one or more of the initial course of panels 2005 is positioned onto the starter strip 2100, the panel 2005 may be fixed into its position. This is achieved by mounting and fastening clips 2200 and/or butt-joint clips 2300.
Referring to
To install the clip 2200, the panel 2005, which is in or very near its final installed position, is pulled slightly away from the wall if necessary, in order to provide a clearance for the back plate 2205 of the clip 2200. The clip 2200 is then positioned so that the back plate 2205 is adjacent the base structure 3000 and the clip 2200 is then slid downwardly until the arms engage or mate with corresponding slots or notches 2010 of the panel 2005, each of which is adapted to receive one of the arms 2220. In this regard, the notches 2010 have a spacing, or a multiple of spacings, that corresponds to the spacing between the arms 2220. The engagement of the arms 2220 and the notches 2010 holds the clip 2200 in a fixed lateral position, e.g., a fixed horizontal position along the base structure 3000. Further, engagement between the bottoms of the arms 2220 and the bottoms of the notches 2010 provide a set vertical position for the arms, and, accordingly, the clip 2200.
To allow ease of insertion, the notches 2010 may be slightly wider than the arms 2220. Further, the lateral positioning of the clip may be constrained in one direction by contact between the panel 2005 and one of the arms, and constrained in the other direction by contact between the panel 2005 and the other one of the arms. For example the portion of the panel 2005 disposed between the two notches 2010 receiving the two arms 2220, may constrain the clip 2200 by contacting the faces inner faces of the arms 2220. Similarly, oppositely disposed portions of the panel 2005 adjacent respective notches 2010 may restrain the lateral movement of the clip by contacting laterally outward faces of the arms 2220. In this regard, it should be understood that any combination of contact between the arms 2220, and the material of the board 2005 adjacent notches 2010 may act to laterally restrain the clip 2200.
Although the panels 2005 have notches 2010, it should be understood that other locating features may be provided. For example, through holes or apertures may be provided that mate with corresponding projections of the clips.
With the clip 2200 positioned with its back plate between the panel 2005 and the base structure 3000 and its arms 2220 fully inserted into the notches 2010, the clip 2200 is fastened by driving a fastened to the base structure 3000, e.g., wall, by driving a fastener through the fastener hole 2210 into the base structure 3000. The fastener may be, e.g., a galvanized roofing nail or ring shank nail, having a length of, e.g., 1¼ inches or longer. It should be understood, however, that other fasteners may be provided in place of, or in addition to nails. For examples, the fastener may include a screw driven through the fastener hole 2210 and/or structural adhesives applied, e.g., between the back plate 2205 and the base structure 3000. Further, although a single fastener hole 2210 is illustrated, it should be understood that the clip 2200 may include additional fastener holes 2210.
The fastened clip 2200 serves to prevent upward movement of the panel 2005 below the clip, as well as preventing the upper portion of the panel 2005 from moving outwardly away from the clip and underlying base structure 3000. This latter function is performed via the extension of the lower panel 2005 (between the slots receiving the arms 2220) between the back plate 2205 (as well as base structure 3000) and a plate 2225 supported by and spanning between the arms 2220. Thus the positioning of the plate 2225 in front of the underlying portion of the panel 2005 constrains outward movement of the top of the panel 2005 away from the clip 2200 and the underlying base structure 3000.
It is noted that the upper projection 2215 is an integral or monolithic extension of the plate 2225. It should be understood, however, that these elements may be formed separately.
The clip 2200 includes at a lower location a bead or projection 2230 that may assist with spacing the panel 2005 away from the base structure 3000, e.g., to facilitate moisture drainage behind the panels 2005 when installed.
The back plate 2205 of the clip 2200 includes a rectangular aperture 2235 at a location opposite the plate 2225 and projection 2215. It should be understood, however, that the aperture may be omitted or provided in any appropriate shape. However, the aperture 2235 may, e.g., facilitate the manufacture of the clip 2200.
Where, e.g., two panels 2005 meet along the length of a course of panels, a butt-joint clip 2300 may be provided. The butt joint clip 2300 shares may features in common with the clip 2200 but differs in that it is configured to mate adjacent end-to-end boards 2005 at a butt joint. In this regard, the butt-joint clip in effect provides two spaced-apart clip structures, with a predetermined spacing within a single clip 2300. Thus, the clip 2300 includes two sets of two arms 2320 (for a total of four), two projections 2315, two plates 2325, and two apertures 2335, which perform functions analogous to corresponding features of clip 2200 described above. The butt-joint clip 2300 also includes a bead or projection 2330 that performs a function analogous to the projection 2230 of the clip 2200.
As illustrated in
Once positioned, the butt-joint clip is fastened in the same manner as the clip 2200. That is, the butt-joint clip 2300 is fastened to the base structure 3000, e.g., wall, by driving a fastener through the fastener hole 2310 and into the base structure 3000. The fastener may be, e.g., a galvanized roofing nail or ring shank nail, having a length of, e.g., 1¼ inches or longer. It should be understood, however, that other fasteners may be provided in place of, or in addition to nails. For examples, the fastener may include a screw driven through the fastener hole 2310 and/or structural adhesives applied, e.g., between the back plate 2305 and the base structure 3000. Further, although a single fastener hole 2310 is illustrated, it should be understood that the clip 2300 may include additional fastener holes 2310.
When the next course of panels 2005 is positioned, e.g., above the clips 2200 and butt-joint clip 2300, the channels 2030 of the panels 2005 are mated with the projections 2215 and projections 2315 of the clips 2200 and butt-joint clip 2300. The height of the positioned panel 2005 may be set by contact between the upper projections 2215, 2315 and the channel 2035 of the panel 2005. It should be understood, however, that the height of the positioned panel 2005 may be set by contact between the projection 2030 of the panel 2005 and the lower panel(s) 2005 and/or the tops of the arms 2220 and/or 2320.
Referring to
The clip arrangement of
It should be appreciated that clips 2600 and/or butt-joint clips 2700 may be used interchangeably and in conjunction with clips 2200 and/or butt-joint clips 2300.
The clips and/or butt-joint clips may be positioned so that there is a fastener driven into every stud of the base structure 3000, e.g., every 16 inches.
Although the siding system 2000 includes clips 2200 that differ from butt joint clips 2300, it should be appreciated that a single clip design may be provided that is adapted to perform in both butt-joint and non-butt-joint applications. However, the differing clip designs of the system 2000 may be more economical as they may allow for smaller clips 2200 at locations other than butt joints.
Referring to
The starter strip 2100, the clips 2200, 2600, and the butt-joint clips 2300, 2700 may be formed of any appropriate material, such as, e.g., recycled polymer, metal, e.g., steel, and/or any other suitable material.
A method according to an example embodiment of the present invention utilizes, e.g., siding panels 2005, the starter strip 2100, clips 2200, 2600, and butt-joint clips 2300, 2700 in conjunction with a base structure 3000. The method includes snapping a level chalk line on the base structure 3000 and fastening a starter strip 2100, every, e.g., 8″, and to every stud. The strip 2100 may be positioned with a clearance, e.g., at least 1″, to the corner of the base structure 3000, e.g., a building, to allow fastening of end trim 3100. A ½-inch clearance may be left between the bottom of the strip 2100 and the floor or ground surface to allow for proper drainage through the weep holes in the strip 2100.
A vertical guide line may also be marked, e.g., 2½ inches from the edge of the structure 3000 to indicate where the panels should begin or end with relation to the edge.
After the starter strip 2100 is fastened to the wall of the structure 3000, a first course, or row, of boards 2005, e.g., clapboard, is positioned onto the starter strip. Once the initial, or bottom, course is positioned, the initial course may be checked to ensure that it is level. After ensuring the course is level, the boards or panels 2005 of the initial course is fastened into place by fitting clips 2200, 2600 into the first, or end, set of slots of the first course, as illustrated in
The next course is then positioned, e.g., snapped, into place over the clips 2200, 2300 and/or butt-joint clips 2600, 2700 securing the upper portion of the initial course. Thus, the panels 2005 of this second course is secured at their lower ends from outward movement away from the base wall onto which the panels 2005 are installed. The upper ends of the panels 2005 are then secured by mounting clips 2200, 2600 and/or butt-joint clips 2300, 2700 into the slots 2010 along the panels 2010 and driving fasteners through the respective fastener holes or apertures 2210, 2610 and/or 2310, 2710. Where panels 2005 need to be cut, it may be preferable to cut down a slot so that the resulting ends will be flush. In this regard, the slots 2010 may be dimensioned to approximate the width of a typical saw-blade cut.
The system 2000 is suitable for preventing moisture from being trapped behind the boards or starter strip. Further, the panels may be snapped into place over each row of clips, butt-joint clips, and/or fasteners, and can be visually checked for correct alignment. A further advantage is that the butt end joints are aligned and correctly gapped. Further, the clips (i.e., clips and butt-joint clips) and panel slots 2010 control horizontal expansion and prevent “oilcan” effect after installation. This expansion/contraction control mechanism is advantageously disposed at the thinner portion of the panels. The clips (i.e., clips and butt-joint clips) can be installed, e.g., with guns or hand-nailed, and may be formed from recycled materials.
The board geometry and clip system allows for quick clip engagement with a “drop-from-top” installation, and allowing the top panel to engage the bottom panel without any additional tools.
Moreover, the notch and clip engagement allows the forces, e.g., from thermal expansion/contraction and/or wind, to be spread along a wider area (slot-to-slot), which allows for better wind performance and minimize or eliminate buckling.
Further, the system allows for an easy butt joint without the use of adhesives, and can be coupled with a tongue-and-groove design for a complete seal.
The clips 2200, 2300 and butt-joint clips 2300, 2700 create a gap 3200 between the installed panels 2005 and the base structure 3000 to prevent the trapping of moisture behind the panels 2005. The gap created by the system allows, e.g., a better appearance, since the panels can bridge wall imperfections, better water drainage, better insulating value for the wall (the air gap), especially with the use of a reflective house wrap.
As regards the interlocking geometry and clip arrangements described above, it should be understood that the siding panels may be formed of the composite material described above or any other appropriate material, e.g., other cellulosic or non-cellulosic composites, polymers, and/or wood. However, the materials set forth herein may be particularly suitable and/or advantageous.
The panels 2005 may be cut from a celuka billet, at a diagonal, and the inside lower density foam becomes the outer show surface, as described in U.S. Provisional Patent Application No. 61/118,109, which is herein incorporated in its entirely by reference thereto. The billet process is decoupled from the siding fabrication, reducing the number of machines and dies necessary. The lower density outer surface may provide, e.g., a cedar-like surface texture. The celuka (higher density) back restricts movement, e.g., due to thermal expansion/contraction, of the lower density show surface. Thus, a low expansion and contraction design is coupled with a low expansion and contraction formula, which may be suitable for performance reliability.
The clip and locking design allows for one-operator installation with ease, while also performing additional function in restricting the movement of the board, and significantly improving the wind loading of the system.
In addition, the space created behind the panels allows for drainage and the air space between the panels and the walls allows for an increased R-value for the total system, particularly when coupled with a reflective house wrap.
Further, the PVC foam show surface, with its rough texture, substantially improves adhesion of, e.g., decoration, film, coating, etc., and allows for easy post decoration embossing, e.g., for an authentic appearance.
While the invention has been described with reference to a preferred embodiment, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.
The examples listed below are intended to represent possible compositions and methods of preparing siding panels of the present invention. It is understood that the materials and amounts, as well as the methods, do not necessarily limit the scope of the invention.
A siding panel according to the present invention is prepared having the composition set forth in Table 2.
The ingredients from Table 2 are loaded into its on-line feeders which is calibrated for each individual material dose rate. The raw material feeder systems used to make may be volumetric or gravimetric, or combinations of each. These feeder systems deliver the pre-calibrated volume or weight of each material to a central neck piece which is attached to the feed port of the extruder. Materials are delivered in a “Starve feed” mode which allows the extruder screws to be covered approximately 90% of total depth.
The raw materials described in the preceding paragraph are mixed in an extruder. The extruder is a counter-rotating, profile twin screws (either conical or parallel screws). The extruder melt-mixes, or flux's, the compound ingredients using shear, heat, and pressure to form a homogeneous molten mass containing an evenly distributed mixture of the raw materials. Melt temperature is the extruder is of 350-360 degree with a pressure of about 1200-3000 psi. The extrusion is performed at a rate about 300 pounds per hour (conical) or about 1200 pounds per hour (dual-strand). The extrusion process prepares the compound to be shaped into the siding panel form that becomes the final product.
The next part of the process is the exit of the molten or fluxed compound from the extruder into the die. The process uses a Celuka die design, which enables the foamed vinyl compound to yield a siding panel that is dense at the surface with an integral skin on all sides. The product density gradient goes from a high density surface to a lower density (foamed) core. The Celuka die is attached to the end of the extruder and receives the molten or fluxed compound. The die is a high inventory, advancing compression streamlined Celuka die, which is configured using a series of sequential plates and mandrels. The die forms the initial shape of the siding panel.
The next process phase is the calibration phase. The calibration step involves receiving the still hot formed panel shape from the die and finishing the formation of the siding panel. A small lead-in plate at 55° F. is employed to presize the extruded siding panel. The extruded panel then passes through a train of 6-1′ foot long dry-sleeve calibrators that contain water and vacuum slots. The calibrator train helps form the tough integral skin and through the use of water and vacuum form and stabilize the final detailed shape of the siding panel.
After calibration the siding panel enters a series of cooling tanks equipped with chilled water spray systems. This chilled water spray is applied to the siding panel on all sides and continues the cooling process of the siding panel. This section of the process can be long, sometimes exceeding 50 to 60 feet. The spray tanks are typically operated under vacuum to help maintain the calibration shaped siding panel. The spray tanks are typically equipped with rollers or templates that continue to hold the siding panel shape as cooling progresses.
Next, the siding panel exits the vacuum cooling tanks and is put through an embosser that embosses the grain pattern into the surface of the panel. To accomplish the embossing, the siding panel is surface heated using an IR light source to prepare the siding panel surface to receive the embossing pattern. The surface temp is about 220° F. on the embossing surface, with a compensating heat on the opposite surface to avoid warping. The hydraulic embosser rolls are heated, with the top roll at about 350-400° F. and the bottom roll at about 250-300° F., and applies a pressure of 800-1200 pli.
The siding panel is allowed to cool slightly before being cut to length. These lengths may be, e.g., 12′, 16′, and 20′ long. The saw is part of the puller system which carefully controls the speed of the panel as it enters the calibration stage until it is cut to length.
The coating process involves the use of a liquid spray applied coating. This process takes the uncoated but embossed panels and applies an acrylic-urethane based solvent spray coating containing all the necessary ingredients needed to provide a durable weather fast finish to the siding panel. The uncoated siding panel is preheated using an IR heat source to about 180-200° F. The acrylic-urethane coating is applied so that the final dry coating has a thickness of between about 0.0020 inch to about 0.0025 inch on the top (embossed) surface and a thickness of about 0.0010 inch on the sides. The siding panel is coated at a rate of 80 to 100 feet per minute. After coating the siding panel passes through an open area of 50-60 feet followed by a one hundred foot convection oven at about 180° F. (to maintain a panel temperature below 160° F.).
The FSI, measured according to the procedures outlined in ASTM E 84-06, for a 2 inch by 4 inch board of the composite material was 20.
A siding panel having the same substrate composition as in example 1 is prepared and used in the UV coating process.
The UV-curable urethane/acrylic coating used to coat the panel has the composition set forth below:
The urethane/acrylic monomer/oligomer composition is transferred to an appropriate vessel. The photo initiator is in liquid form and is mechanically stirred into the batch. Once the photoinitiator is added, the material must be kept away from any UV light sources and the material will have at least a two year shelf life when drummed and sealed.
The pigments (Ferro Geode) are dispersed in a reactive Sartomer oligomer (PDMA) and are supplied in liquid form. The Pigment concentrate dispersion is mixed in with the other components in stainless steel vessels using a propeller mixer at low speed so as to avoid air entrapment. Small additions of surfactant defoamers are used.
The Nano Byk 3601 40 nm aluminum oxide in TPGDA is added to the coating mixture. This ingredient is a liquid which is an oligomer reactant and is mixed using mild propeller action. The Silica is mixed into the coating mixture as above.
The siding panel is transported through the process equipment by belt or roller conveyors. The siding panel is cleaned at a rotary brush station where the brushes are nylon or abrasive impregnated nylon filaments. The coating is applied in a spray chamber where automatic paint guns apply the coating to the product surface at a thickness of 1 mil. The coating is delivered to the spray gun by a circulating system. Air for atomizing the coating is also supplied. To maximize coating efficiency, overspray is captured in drip pans and filter banks.
The coating is cured in a UV oven which is configured with Fusion “V” and “H” bulbs. Heat from the enclosed oven is removed by an exhaust system. To apply coating at a thickness greater than 1 mil the product may be processed through the process line a second time or an additional spray chamber and UV oven added to the described configuration.
This application claims benefit to U.S. Provisional Patent Application Ser. No. 61/118,102, filed on Nov. 26, 2008, which is expressly incorporated herein in its entirety by reference thereto.
| Number | Date | Country | |
|---|---|---|---|
| 61118102 | Nov 2008 | US |
