Patent Application
20070039703
The present invention relates generally to chopped strand mats utilized in roofing applications, and more particularly, to chopped strand glass mats that have improved hot wet tensile strengths.
Glass fibers are commonly used as reinforcements in the building composite industry because they do not shrink or stretch in response to changing atmospheric conditions. Roofing materials such as roofing shingles, roll roofing, and commercial roofing, are typically constructed of a glass fiber mat, an asphalt coating on the fibrous mat, and a surface layer of granules embedded in the asphalt coating.
To form a chopped strand mat suitable for use in a roofing material, glass fibers are first formed by attenuating streams of a molten glass material from a bushing or orifice. The molten glass may be attenuated by a winder which collects gathered filaments into a package or by rollers which pull the fibers before they are collected and chopped. An aqueous sizing composition is typically applied to the fibers after they are drawn from the bushing to protect the fibers from breakage during subsequent processing, to retard interfilament abrasion, and to improve the compatibility of the fibers with the matrix resins that are to be reinforced. After the fibers are treated with the sizing composition, they may be packaged in their wet condition as wet use chopped strand glass (WUCS).
The wet, chopped fibers are then dispersed in a water slurry which contains surfactants, viscosity modifiers, dispersants, and/or other chemical agents and agitated to disperse the fibers. The slurry containing the dispersed fibers is then deposited onto a moving screen where a substantial portion of the water is removed. A polymeric binder is then applied, and the resulting mat is heated to remove the remaining water and cure the binder. A urea-formaldehyde binder is typically utilized due to its low cost. Next, asphalt is applied to the mat, such as by spraying the asphalt onto one or both sides of the mat or by passing the mat through a bath of molten asphalt to place a layer of asphalt on both sides of the mat. A protective coating of granules may be applied to the asphalt-coated mat. The asphalt-granule coated mat may be used to form a variety of roofing materials, such as a roofing shingle.
Properties such as tear strength, dry tensile strength, and wet tensile strength are measured to determine the usefulness of the chopped strand glass mat in roofing applications. One especially important property for a roofing mat is the retention of hot wet tensile strength. The hot wet strength provides an estimation of the durability of the roofing mat. However, some of the conventional binders utilized to form the roofing mats, such as urea-formaldehyde resins, tend to deteriorate under wet conditions such as would be found in an external environment in which the roofing mat would be used. Modifying the urea-formaldehyde binder, such as with a latex modifier, has been found to increase the tear strength as well as the hot tensile strength over unmodified urea-formaldehyde resins. Other examples of modifying the binder to improve mat properties such as tensile properties and tear strength are set forth below.
U.S. Pat. No. 6,642,299 to Wertz et al. discloses an aqueous fiber mat adhesive binder composition that includes a thermosetting urea-formaldehyde resin and an additive that is either (1) a styrene acrylic acid or styrene acrylate, (2) an adduct of styrene, maleic anhydride, and an acrylic acid or acrylate, or (3) a physical mixture of a styrene acrylic acid or styrene-acrylate copolymer and a styrene-maleic anhydride copolymer. The binder may be used in the formation of glass fiber mats that demonstrate hot tensile strength tensile retention.
U.S. Pat. No. 6,566,459 to Dopico et al. discloses a melamine-urea-formaldehyde resin modified with a cyclic urea prepolymer and sodium metabisulfite. It is asserted that glass mats formed with the modified melamine-urea-formaldehyde resins have improved hot wet tensile strength retention and superior moisture resistance compared to urea-formaldehyde resins.
U.S. Pat. No. 6,384,116 to Chan et al. describes a binder composition that is formed of a urea-formaldehyde resin modified with a water soluble non-ionic amine oxide. Optionally, the urea-formaldehyde resin may be further modified with an anionic acrylic latex and/or a water soluble polymer having a weight average molecular weight from 100,000- 2,000,000. It is asserted that the tensile strengths of glass mats formed with the modified urea-fornaldehyde resin possess superior tear strength and improved tensile strengths.
U.S. Pat. Nos. 5,914,365 and 6,084,021 to Chang et al. describe an aqueous binder composition that contains a urea-formaldehyde resin modified with a water-soluble styrene-maleic anhydride copolymer (SMA). The binder composition is used in the preparation of fiber mats which may be used as substrates in the manufacture of roofing shingles and composite flooring. It is asserted that glass fiber mats made using the binder compositions exhibit enhanced wet tensile strength, wet mat strength, dry tensile strength, and tear strength.
U.S. Pat. No. 5,851,933 to Swartz et al. disclose methods for making non-woven fibrous mats that produce superior tear strengths in roofing products. The mats are formed by a wet-laid process in which the applied binder contains an aqueous urea-formaldehyde resin and a self-crosslinking copolymer of a vinyl acrylic or polyvinyl acetate.
U.S. Pat. Nos. 5,445,878, 5,518,586, and 5,656,366 to Mirous describe a urea-formaldehyde resin modified with a water-insoluble anionic phosphate ester. Glass fiber mats formed using the modified urea-formaldehyde resin as a binder and a hydroxyethyl cellulose-containing white water glass slurry is asserted to exhibit high tear strengths.
U.S. Pat. No. 4,430,158 to Jackey et al. discloses a method of improving the wet tensile strength of sized glass fiber mats by applying a binder composition that contains a urea-formaldehyde resin and 0.01 -5% by weight of a surfactant that is highly soluble and capable of wetting the surfaces of the sized glass fibers. The surfactant is preferably an ionic surfactant such as a sodium dodecylbenzene sulfonate.
U.S. Patent Publication No. 2005/0070186 to Shoemake et al. describes a thermosetting urea-formaldehyde resin modified with a binding-enhancing amount of a protein useful as a binder in the formation of glass fiber mats. Preferably the protein is a vegetable protein, and even more preferably, a soy protein. The glass mats are asserted to demonstrate wet tensile strengths, tear strengths, and dry tensile strengths substantially equivalent to urea-formaldehyde resin binders modified with synthetic additives.
Despite these disclosures, there exists a need in the art for new binder compositions for fiber mats that provide even further improvements in mat tensile and/or tear strength properties.
It is an object of the present invention to provide a two-part binder composition formed of a binder pre-mix and at least one coupling agent. The choice of binder forming the binder pre-mix is not particularly limited, and may include a modified urea-formaldehyde binder, a non-modified urea-formaldehyde binder, formaldehyde-free binders, and combinations thereof. In addition, the binders may formed as a “one-part package” in which the binder is pre-mixed with a modifying agent and packaged as a one component system or a “two-part package” in which the binder and the modifying agent are not pre-mixed. In a preferred embodiment, the binder is a standard urea-formaldehyde binder modified with a styrene butadiene rubber latex modifier. Suitable examples of coupling agents for use in the inventive binder composition include silane coupling agents and reactive siloxanes. In preferred embodiments, the coupling agent is an aminosilane coupling agent. A weak organic acid may be added to the binder composition to hydrolyze the silane coupling agent.
It is also an object of the present invention to provide a chopped strand mat for use in roofing applications that has improved hot wet tensile strength. The chopped strand may be formed of a plurality of glass fibers held together in a sheet form by a two-part binder composition. The glass fibers used to form the chopped strand glass mats may be any type of glass fiber, such as A-type glass fibers, C-type glass fibers, E-type glass fibers, S-type glass fibers, E-CR-type glass fibers (e.g., Advantex® glass fibers commercially available from Owens Corning), wool glass fibers, or combinations thereof. Optionally, other reinforcing fibers such as mineral fibers, carbon fibers, ceramic fibers, natural fibers, and/or synthetic fibers may present in the chopped strand mat in addition to the glass fibers. The binder is preferably the two-part binder composition described above.
It is a further object of the present invention to provide a method of making a chopped strand glass mat that has improved hot wet tensile strengths in which a coupling agent is added to the chopped strand mat via the binder in a wet-laid mat processing line. Chopped glass fibers are added to white water containing various surfactants, viscosity modifiers, defoaming agents, and/or other chemical agents with agitation to form a glass fiber slurry. The slurry is deposited onto a moving forming wire or foraminous conveyor to form a web of intermeshed fibers. Water is removed, such as by a vacuum system, and a binder containing at least one coupling agent is applied to the web of fibers. The binder-coated web is passed through a drying oven to remove any of the water remaining in the web, cure the binder, and form the chopped strand glass mat. The binder is preferably the two-part binder composition described above.
It is yet another object of the present invention to provide a method of making a chopped strand glass mat that has improved hot wet tensile strengths in which a coupling agent (or coupling agents) is separately added to the web of chopped fibers during the formation of the chopped strand mat in a wet-laid mat processing line. Chopped glass fibers are added to white water containing various surfactants, viscosity modifiers, defoaming agents, and/or other chemical agents with agitation to form a glass fiber slurry. The slurry is deposited onto a moving forming wire or foraminous conveyor to form a web of intermeshed fibers. Water is removed from the web by conventional vacuum or air suction system. A binder is applied to the web by a binder applicator. The binder utilized is not particularly limited, and may include any conventional one- or two-part binder compositions known to those of skill the art. A coupling agent is also applied to the surface of the web, either before or after the application of the binder. The coupling agent may be added to the web at any location prior to the web entering the drying oven. Suitable coupling agents include silane coupling agents and reactive siloxanes. Preferably, the coupling agent is one or more aminosilanes. Once the binder and coupling agent have been applied to the web, the web is passed through a drying oven to remove any remaining water and cure the binder composition.
It is another object of the present invention to provide a method of forming a chopped strand mat that has improved hot wet tensile strengths in which a coupling agent is added to the white water in a wet-laid, chopped strand mat processing line. Suitable coupling agents include silane coupling agents and reactive siloxanes. Preferably, the coupling agent is one or more aminosilanes. Glass fibers are deposited into the white water containing the coupling agent(s) and any conventionally used surfactants, viscosity modifiers, defoaming agents and/or other suitable chemical agents to form a glass slurry. The slurry is deposited onto a foraminous conveyor or wire mesh and a substantial portion of the water is removed, such as by a vacuum system. A binder is applied to the web of fibers, the web is conveyed to a drying oven where the remaining water is removed, and the binder is cured. The binder may be any conventional binder known to those of skill in the art.
It is an advantage of the present invention that chopped strand mats formed according to any embodiment of the present invention as disclosed herein may be formed with fibers treated with a size composition that does or does not include a coupling agent. As a result, virtually any glass fiber may be utilized in forming the chopped strand glass mats of the present invention.
It is another advantage of the present invention that the two-part binder composition of the present invention may utilized in a chopped strand mat forming process without having to change process parameters or modify the equipment on existing wet-laid mat processing lines.
It is yet another advantage of the present invention that the application or inclusion of at least one coupling agent to the chopped strand mat during a wet-laid mat forming process improves the hot wet tensile strengths of the chopped strand mats.
It is a further advantage of the present that the inclusion of a coupling agent or agents to the chopped strand mat during the wet-laid process results in an improvement in the dry tensile strength of the formed shingles. As a result, permit manufacturers can run their shingle production lines at a faster rate with less tearing or “break up” of the shingles and increase productivity may be achieved by.
The foregoing and other objects, features, and advantages of the invention will appear more fully hereinafter from a consideration of the detailed description that follows. It is to be expressly understood, however, that the drawings are for illustrative purposes and are not to be construed as defining the limits of the invention.
The advantages of this invention will be apparent upon consideration of the following detailed disclosure of the invention, especially when taken in conjunction with the accompanying drawings wherein:
Unless defined otherwise, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the invention belongs. Although any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, the preferred methods and materials are described herein. All references cited herein, including published or corresponding U.S. or foreign patent applications, issued U.S. or foreign patents, or any other references, are each incorporated by reference in their entireties, including all data, tables, figures, and text presented in the cited references.
In the drawings, the thickness of the lines, layers, and regions may be exaggerated for clarity. It is to be noted that like numbers found throughout the figures denote like elements. It will be understood that when an element is referred to as being “on,” another element, it can be directly on or against the other element or intervening elements may be present. It is also to be understood that the term “web” and “mat” may be used interchangeably herein.
The present invention relates to non-woven, wet-laid chopped strand glass mats for use in roofing applications that have improved hot wet tensile strengths. The present invention is predicated, at least in part, on the discovery that improved hot wet tensile strengths in chopped strand mats may be obtained by the application or inclusion of at least one coupling agent to the chopped strand mat during a wet-laid mat forming process. Conventionally, a coupling agent has been added to the size formulation applied to the glass fibers during the formation of the glass fiber.
The glass fibers used to form the chopped strand glass mats may be any type of glass fiber, such as A-type glass fibers, C-type glass fibers, E-type glass fibers, S-type glass fibers, E-CR-type glass fibers (e.g., Advantex® glass fibers commercially available from Owens Corning), wool glass fibers, or combinations thereof. In at least one preferred embodiment, the glass fibers are wet use chopped strand glass fibers (WUCS). Wet use chopped strand glass fibers may be formed by conventional processes known in the art. It is desirable that the wet use chopped strand glass fibers have a moisture content of from 5-30%, and even more desirably a moisture content of from 5-15%.
The use of other reinforcing fibers such as mineral fibers, carbon fibers, ceramic fibers, natural fibers, and/or synthetic fibers such as polyester, polyethylene, polyethylene terephthalate, polyolefin, and/or polypropylene fibers in the chopped strand glass mat is considered to be within the purview of the invention. As used herein, the term “natural fiber” is meant to indicate plant fibers extracted from any part of a plant, including, but not limited to, the stem, seeds, leaves, roots, or bast. The term “synthetic fibers” as used herein is meant to indicate any man-made fiber having suitable reinforcing characteristics. However, it is preferred that all of the fibers in the chopped strand mat are glass fibers.
The glass fibers may be formed by conventional methods known to those of skill in the art. For example, the glass fibers may be formed by attenuating streams of a molten glass material from a bushing or orifice. The attenuated glass fibers may have diameters of about 5-30 microns, preferably from 10-20 microns. After the glass fibers are drawn from the bushing, an aqueous sizing composition is applied to the fibers. The sizing may be applied by conventional methods such as by an application roller or by spraying the size directly onto the fibers. The size protects the glass fibers from breakage during subsequent processing, helps to retard interfilament abrasion, and ensures the integrity of the strands of glass fibers, e.g., the interconnection of the glass filaments that form the strand.
The size composition applied to the glass fibers typically includes one or more film forming agents (such as a polyvinyl alcohol film former, cellulose film former, polyurethane film former, a polyester film former, and/or an epoxy resin film former), at least one lubricant, and at least one silane coupling agent (such as an aminosilane or methacryloxy silane coupling agent). The coupling agent chemically interacts with the glass fibers to couple the glass fibers with a binder or polymer matrix. When needed, a weak acid such as acetic acid, boric acid, metaboric acid, succinic acid, citric acid, formic acid, and/or polyacrylic acids may be added to the size composition to assist in the hydrolysis of the silane coupling agent. The size composition may be applied to the glass fibers with a Loss on Ignition (LOI) of approximately 0.05-2.0% on the dried fiber. LOI may be defined as the percentage of organic solid matter that remains on the glass fiber surfaces after heating them to a temperature sufficient to burn or pyrolyze the organic size from the fibers.
The inclusion of a coupling agent in the size composition requires that the sized fiber be aged a predetermined period of time to permit the coupling agent to react with the fiber so that the coupling agent is not washed away from the fiber in the white water slurry of a wet-laid mat forming process such as is described in detail below. It is hypothesized that by removing the coupling agent from the sizing composition applied to the glass fibers during fiber formation and applying or incorporating a coupling agent or agents to the chopped strand mat in the mat forming line, the need to age the glass fibers prior to formation into a chopped strand mat may be reduced or eliminated. It is believed that the elimination of the coupling agent the size composition will result in fibers having improved stability and a longer shelf life. In addition, it is believed that fibers sized with a size that does not include a coupling agent would have the ability to be immediately utilized in a wet-laid process (e.g., directly from a glass forming line), which would decrease the total manufacturing time for the production of chopped strand mats and roofing shingles.
It is further hypothesized that by removing the coupling agent from the sizing composition, the negative impact caused by chemical interactions between the coupling agent and the other chemicals in the size composition (e.g., lubricants and dispersants) will be eliminated and the efficiency of the remaining chemicals in the size will be increased. In particular, because there is little to no reaction with the lubricants in the size composition, it is believed that product dispersion performance will be improved.
In conventional size compositions, the coupling agents react with the glass fibers. Occasionally, the coupling agent is highly reactive (such as aminosilane A-1100 from GE Silicones) and reacts with more than one glass fiber simultaneously. This inter-reaction between the glass fibers may cause a “clumping” or interconnection of the glass fibers. By removing the coupling agent from the size composition, there is no active agent remaining within the size composition to react with the glass fibers and cause such undesirable “clumping”. Therefore, a problem that was caused by the coupling agent in the size (i.e., the interconnection of the glass fibers by the coupling agent) is eliminated by the present invention.
After the fibers are treated with the sizing composition, they may be chopped and packaged in their wet condition as wet use chopped strand glass (WUCS) and processed into a wet-laid chopped strand mat as described below. It is to be appreciated that the chopped strand mats formed according to any embodiment of the present invention as disclosed herein may be formed with fibers treated with a size composition that does or does not include a coupling agent. This is an advantageous feature in that unlike conventional wet-laid processes, virtually any glass fiber may be utilized in forming the chopped strand glass mats of the present invention. The chopped glass fibers may have a length of 0.5-2.0 inches. Preferably, the chopped glass fibers have a length of 1-1.5 inches.
In one embodiment of the invention, the coupling agent (or agents) is added to the chopped strand mat as part of a two-part binder composition. In particular, the chopped strand mat is formed of a plurality of glass fibers held together in a sheet form by a two-part binder composition that includes a binder pre-mix and a coupling agent or a coupling agent package that contains two or more coupling agents.
An exemplary process of forming the chopped strand mat utilizing the inventive two-part binder composition is illustrated in
The two-part binder composition of the present invention may utilized in a chopped strand mat forming process without having to change process parameters such as oven drying time, conveyor speed, etc. In addition, the inventive binder composition may be applied to the chopped strand mat in conventional wet-laid mat manufacturing lines without a modification of the existing equipment.
The two-part binder composition is formed of a binder pre-mix and a coupling agent or a coupling agent package containing two or more coupling agents. The binder pre-mix may include a modified or non-modified formaldehyde binder (e.g. a phenol-formaldehyde binder), a modified urea-formaldehyde binder (e.g., modified with latex, styrene butadiene latex, a styrene/maleic anhydride copolymer, polyvinyl acetate, a vinyl acrylic copolymer, melamine, or melamine derivatives), a non-modified urea-formaldehyde binder, formaldehyde-free binders such as an acrylic binder, a styrene acrylonitrile binder, a styrene butadiene rubber binder, polyvinyl acetate binders, vinyl acrylic binders, polyurethane binders, and combinations thereof. In addition, the binders may formed as a “one-part package” in which the binder is pre-mixed with a modifying agent and packaged as a one component system or a “two-part package” in which the binder and the modifying agent are not pre-mixed. In a preferred embodiment, the binder is a standard urea-formaldehyde binder modified with a styrene butadiene rubber latex modifier such as DL 490NA (available commercially from Dow Reichhold).
Examples of suitable binders for use in the binder pre-mix of the present invention include Bordon FG 472 (a urea-formaldehyde resin binder commercially available from Bordon Chemical Co.), GP®-2984 (a modified urea-formaldehyde resin binder available from Georgia-Pacific), GP®-2948 (a modified urea-formaldehyde resin binder available from Georgia-Pacific), and GP®-2928 (a modified urea-formaldehyde resin binder available from Georgia-Pacific). The binder pre-mix may be present in the binder composition in an amount of 40-80% by weight based on the active solids in the binder composition, and preferably from 55-70% by weight based on the active solids in the binder composition.
The inventive binder composition also includes at least one coupling agent. It is to be appreciated that the coupling agents described below may be utilized in any of the embodiments described herein. Any suitable coupling agent identified by one of skill in the art may be utilized in the instant invention. The coupling agent or coupling agent package may be present in the binder composition in an amount of 0.02-5.0% by weight based on the active solids in the binder composition, preferably in an amount of 0.1-1.0 % by weight of the active solids in the binder composition, even more preferably 0.1-0.5% by weight of the active solids in the binder composition, and most preferably 0.2-0.5% by weight of the active solids in the binder composition.
Preferably, at least one of the coupling agents is a silane coupling agent. Examples of silane coupling agents which may be used in the present size composition may be characterized by the functional groups amino, epoxy, vinyl, methacryloxy, azido, ureido, and isocyanato. Suitable silane coupling agents include, but are not limited to, aminosilanes, silane esters, vinyl silanes, methacryloxy silanes, epoxy silanes, sulfur silanes, ureido silanes, and isocyanato silanes. Specific non-limiting examples of silane coupling agents for use in the instant invention include γ-aminopropyltriethoxysilane (A-1100), n-phenyl-γ-aminopropyltrimethoxysilane (Y-9669), n-trimethoxy-silyl-propyl-ethylene-diamine (A-1120), methyl-trichlorosilane (A-154), γ-chloropropyl-trimethoxy-silane (A-143), vinyl-triacetoxy silane (A-188), methyltrimethoxysilane (A-1630). Other examples of suitable silane coupling agents for are set forth in Table 1. All of the silane coupling agents identified above and in Table 1 are available commercially from GE Silicones.
The silane coupling agents used in the present invention may be replaced by alternative coupling agents or mixtures. For example, A-1387 may be replaced by a version in which the methanol solvent is replaced by ethanol. A-1126, an aminosilane coupling agent including a mixture of approximately 24% by weight diaminosilane modified by a surfactant in a methanol solution (GE Silicones), may be replaced with trimethoxy-silyl-propyl-ethylene-diamine (Z-6020 from Dow Corning). A-1120 or Z-6020 may be substituted by a pre-hydrolyzed version. Z-6020 may be replaced by Z-6137, a pre-hydrolyzed version lacking the alcohol solvent and including 33% diaminosilane in water at a concentration of 24% solids (commercially available from Dow Corning). I addition, A- 1100 may be replaced by its hydrolyzed form Y-9244, which will reduce or eliminate the ethanol emission.
Vinyl aminosilanes, such as Z-6032 and Z-6224, both commercially available from Dow Corning, are also useful as coupling agents in the present invention. Z-6032 is a 40% silane solution in methanol. A specific gravity of 0.9% at 25° C., a refractive index of 1.395 at 25° C., and a viscosity of 2.2 at 25° C. The chemical formula is (CH5O)3-SiCH2CH2CH2NHCH2CH2NHCH2—O—CH═CH2—HCl and is designated N-2-(vinyl benzylamino)-ethyl-3-amino propyltrimethoxy silane-monohydrogen chloride. Z-6224 has a specific gravity of 0.88 at 25° C., a refractive index of 1.388 at 25° C. and is the neutralized (chloride-free) version of Z-6032.
In addition, the coupling agent may include a functionalized organic substrate (i.e., at least one organic functional group bonded to an organic substrate). Exemplary types of functionalized organic substrates include alcohols, amines, esters, ethers, hydrocarbons, siloxanes, silazanes, silanes, silanols, lactams, lactones, anhydrides, carbenes, nitrenes, orthoesters, imides, enamines, imines, amides, imides, and olefins. The functionalized organic substrate is capable of interacting and/or reacting with the surface of the glass fibers to provide sufficient coupling or bonding between the glass fibers and the binder material. In particular, one end of the molecule reacts or interacts with the glass surface and the other end of the molecule reacts or interacts with the binder. By choosing one or more suitable functionalized organic substrates for the coupling agent system, desired mechanical properties between the glass fibers and the binder can be obtained.
Another example of compounds useful as coupling agents in the present invention include silicon containing coupling agents (e.g., silane, silanol, and/or siloxane) tailored or functionalized with an organic polymer. For example, silanes tailored with polyurethane are capable of performing coupling agent functions to bond the glass fiber and the binder. Another exanple includes a silanol tailored or functionalized with a polyamide. It is believed that in this example, if the amine is neutralized, a cationic charge forms on the amine, permitting an ionic bond to form between the amine and the glass fiber. The organic portion of the molecule, i.e., the organic polymer, then covalently bonds with the binder.
Reactive siloxanes may also be utilized as coupling agents. Examples of reactive siloxanes include DC-1171, DC-75SF, and DC-2-7887, all commercially available from Dow Corning. Reactive siloxanes are thought to be linear or branched structures with the following monomeric units (I):
R1, R2, R3, R4, R5, and R6 may differ from one monomeric unit to another and may be an alkyl (preferably a methyl group) or a hydride. When branched, R1, R2, R3, R4, R5, and R6 may be formed of one or more monomeric units (I). The reactivity of reactive siloxanes and their ability to act as blocking agents increases with increased number of hydride groups for R1, R2, R3, R4, R5, and R6.
The binder composition may also contain a trace amount of a weak organic acid such as acetic acid, formic acid, succinic acid, and/or citric acid hydrolyze the silane in the coupling agent. It is preferred that the organic acid is acetic acid. The organic acid may be present in the binder composition in an amount of from 0.1-1.0% by weight of the binder composition, preferably 0.3-0.6% by weight of the binder composition.
In addition, the binder composition may optionally contain conventional additives for the improvement of process and product performance such as fire retardants, dyes, oils, fillers, colorants, UV stabilizers, lubricants, wetting agents, surfactants, and/or antistatic agents.
In a second embodiment of the present invention, the coupling agent (or coupling agents) is separately added to the web of chopped fibers during the formation of the chopped strand mat in a wet-laid mat processing line. One exemplary process of separately adding the coupling agent to the chopped strand mat is depicted in
A binder 24 is applied to the web 22 by a binder applicator 26. The binder utilized is not particularly limited, and may include any conventional one- or two-part binder compositions known to those of skill the art. A coupling agent 36 may then be applied to the web (mat) 22 by a suitable applicator 38 such as a spray applicator or a curtain coater. The coupling agent 36 may be added to the fibrous web 22 in an amount up to approximately 1% by weight of the mat 22. The coupling agent may be any one or more of the coupling agents described in detail herein. The coupling agent(s) 36 may be in the form of a liquid, a slurry, an emulsion, or a foam. Preferably, the coupling agent 36 is a liquid. Although
In at least one preferred embodiment of the invention, the chopped strand mat 32 depicted in
In a third embodiment of the present invention, the coupling agent is added to the white water in a wet-laid, chopped strand mat processing line such as is illustrated in
Although the inclusion of a coupling agent or agents to the white water results in the addition of the coupling agent to the chopped strand mat, adding a coupling agent to the white water may be cost-prohibitive due to the large amount of coupling agent that would have to be added to the white water for adhesion onto the glass fibers and the high cost of the coupling agents.
It is to be appreciated that the coupling agent may be added to the chopped strand mat by one or more of the embodiments described above. For example, it may be desirable in some instances to add a coupling agent to the chopped strand mat via the two-part binder composition and to add a coupling agent to the same chopped strand mat independent of the binder composition by a separate applicator. Alternatively, it may be desirable to add a coupling agent to the white water and also add a coupling agent via the two-part binder composition. The application or inclusion of a coupling agent (or agents) to a chopped strand mat by any combined embodiments described herein are considered to be within the purview of the invention.
As discussed above, the application or inclusion of at least one coupling agent to the chopped strand mat during a wet-laid mat forming process improves the hot wet tensile strengths of the chopped strand mats. The ability of a shingle to resist water degradation is a desired property if the shingle is to have long term performance. An estimate of the long term performance of shingles is typically determined in the industry by obtaining the hot wet tensile strengths of the chopped strand mats forming the shingles. It is believed that the hot wet tensile strength performance of the chopped strand mat correlates to the performance of the shingle. For example, an increase or improvement in the hot wet tensile strength results in an increase or improvement in the long term performance in the shingle, whereas a decrease in the hot wet tensile strength results in a decrease in the performance of the shingle. Therefore, it is believed that adding a coupling agent(s) to the chopped strand mat during the wet-laid process as in the present invention, which improves the hot wet tensile strength of the chopped strand mat, would result in shingles having improved lifetime performance.
Additionally, including at least one coupling agent to the chopped strand mat during the wet-laid mat forming process increases the dry tensile strength of a shingle formed from that mat. This increase in tensile strength may permit manufacturers to run their production lines at a faster rate with less tearing or “break up” of the chopped strand mats. As a result, an increase in the productivity may be achieved by the inclusion of a coupling agent or agents to the chopped strand mat during the wet-laid process.
Having generally described this invention, a further understanding can be obtained by reference to certain specific examples illustrated below which are provided for purposes of illustration only and are not intended to be all inclusive or limiting unless otherwise specified.
Binder compositions set forth in Tables 2-6 were prepared in buckets as described generally below. In particular, Control Binder Composition A (Table 2) was prepared by mixing the urea-formaldehyde resin (Bordon FG 472 from Bordon Chemical Co.), the latex binder (DL 490NA from Dow Reichhold), and water.
Binder pre-mixes for inventive Binder Compositions B-E (Tables 3-6) were prepared by mixing the urea-formaldehyde resin (Bordon FG 472), latex binder (DL 490NA from Dow Reichhold), and water. Acetic acid and water were mixed to form an acidic solution. Aminosilanes A-1100 and Y-9669 (GE Silicones) were added to the acidic solutions as designated in Tables 3-6 and moderately agitated to permit hydrolyzation. The hydrolyzed aminosilane(s) were then added to the binder pre-mixes with agitation to form Binder Compositions B-E. Once formed, Binder Compositions B-E were diluted with water to achieve the target mix solids of approximately 50.00%.
(a)urea-formaldehyde resin (Bordon Chemical Co.)
(b)styrene butadiene rubber latex modifier (Dow Reichhold)
(a)urea-formaldehyde resin (Bordon Chemical Co.)
(b)styrene butadiene rubber latex modifier (Dow Reichhold)
(c)γ-aminopropyltriethoxysilane (GE Silicones)
(a)urea-formaldehyde resin (Bordon Chemical Co.)
(b)styrene butadiene rubber latex modifier (Dow Reichhold)
(c)γ-aminopropyltriethoxysilane (GE Silicones)
(a)urea-formaldehyde resin (Bordon Chemical Co.)
(b)styrene butadiene rubber latex modifier (Dow Reichhold)
(c)n-phenyl-γ-aminopropyltrimethoxysilane (GE Silicones)
(a)urea-formaldehyde resin (Bordon Chemical Co.)
(b)styrene butadiene rubber latex modifier (Dow Reichhold)
(c)γ-aminopropyltriethoxysilane (GE Silicones)
(d)n-phenyl-γ-aminopropyltrimethoxysilane (GE Silicones)
E-type chopped strand glass fibers sized with a conventional sizing composition containing one or more film forming agents, at least one lubricant, and at least one coupling agent were formed into chopped strand glass mats on a sheetformer using Binder Compositions A-E. The chopped strand glass fibers had a length of ⅞ of an inch and a percent moisture of 10.92%. A chopped strand mat using Binder Composition A (Control) was replicated to confirm the reproducibility of the forming process and the data for the average of the two tests were used as data in Tables 7 and 8 for Binder Composition A. 2 inch wide test specimens of the chopped strand mats containing Binder Compositions A-E were then evaluated for wet tensile strength on an Instron tensile testing apparatus. Each of the chopped strand mat samples were soaked in 180° F. water for 10 minutes prior to testing for wet tensile strength. The test results are set forth in Table 7.
The chopped strand mat samples using Binder Compositions A-E were then formed into shinglets on an asphalt coating mimic line. The shinglet samples were tested for tear strength in the cross machine direction (CD) on an Elmendorf tear testing apparatus according to the testing procedures set forth in ASTM D3462. The results are set forth in Table 8.
As shown in Table 7, the chopped strand mats formed with inventive Binder Compositions B-E demonstrated a marked improvement in wet tensile strength over the current state of the art. As discussed above, an estimate of the long term performance of shingles is determined in the industry by determining the hot wet tensile strength of the chopped strand mats forming the shingles. It is believed that high hot wet tensile strength performance of the chopped strand mat is related to better long term performance of the shingle. The results set forth in Table 7 illustrates that the chopped strand mats formed with the inventive binder compositions had outstanding wet tensile strengths compared to the current state of the art (Binder Composition A). Thus, it is believed that shingles formed from chopped strand mats formed utilizing the inventive binder composition would have improved long term performance.
In addition, this improvement in the hot wet tensile strengths of the chopped strand mats is achieved without a decrease in the shingle tear strength, as shown in Table 8. This result is an unexpected feature since the addition or increase of a coupling agent in a size formulation for chopped glass fibers commonly results in a reduction in the shingle tear strength.
E-type chopped strand glass fibers sized with a conventional sizing composition containing one or more film forming agents, at least one lubricant, and a coupling agent were formed into chopped strand glass mats on a sheetformer using Binder Compositions A, B, and D set forth in Tables 2, 3, and 5 respectively. The chopped strand glass fibers had a length of 1¼ inches and a percent moisture of 13.22%. A chopped strand mat using Binder Composition A (Control) was replicated to confirm the reproducibility of the forming process and the data for the average of the two tests were used as data in Tables 9 and 10 for Binder Composition A. 2 inch wide test specimens of the chopped strand mats containing Binder Compositions A, B, and D were then evaluated for wet tensile strength on an Instron tensile testing apparatus. Each of the chopped strand mat samples were soaked in 180° F. water for 10 minutes prior to testing for wet tensile strength. The test results are set forth in Table 9.
The chopped strand mat samples using Binder Compositions A, B and D were then formed into shinglets on an asphalt coating mimic line. The shinglet samples were tested for tear strength in the cross machine direction (CD) and machine direction (MD) on an Elmendorf tear testing apparatus according to the testing procedures set forth in ASTM D3462. The shinglet samples were also tested for dry tensile strength in the machine direction (MD) on an Instron tensile testing apparatus. The results are set forth in Table 10.
As shown in Tables 9 and 10, the inclusion of a coupling agent in Binder Compositions B and D improved the hot wet tensile retention of the chopped strand mats with little impact on the tear strength. In addition, as illustrated in Table 10, the inclusion of a coupling agent in the inventive binder compositions used in forming the chopped strand mats demonstrated a positive and significant effect on the shingle dry tensile strength (MD) with a minimal and statistically insignificant change in the total tear strength. This improvement in the dry tensile strength will permit manufacturers to run their shingle production lines at a faster rate with less tearing or “break up” of the shingles. As a result, an increase in productivity may be achieved by the inclusion of a coupling agent or agents to the chopped strand mat during the wet-laid process.
E-type chopped strand glass fibers sized with a conventional sizing composition containing one or more film forming agents, at least one lubricant, and at least one coupling agent were formed into chopped strand glass mats on a sheetforner using Binder Compositions A, B, and D set forth in Tables 2, 3, and 5 respectively. The chopped strand glass fibers had a length of 1 ¼ inches and a percent moisture of 13.69%. A chopped strand mat using Binder Composition A (Control) was replicated to confirm the reproducibility of the forming process and the data for the average of the two tests were used as data in Tables 11 and 12 for Binder Composition A. Wet tensile strength of the chopped strand mats were determined according to the procedure set forth in Example 2 above. The test results are set forth in Table 11. Shinglet samples were then formed and tested for tear strength in both the machine direction (MD) and in the cross machine direction (CD) and dry tensile strength as described in Example 2 above. The results are set forth in Table 12.
As shown in Tables 11 and 12, the inclusion of a coupling agent in the inventive binder compositions improved the hot wet tensile retention of the chopped strand mats with little impact (minimal impact) on the tear strength. In addition, as illustrated in Table 12, the inclusion of a coupling agent in Binder Compositions B and D used to form the chopped strand mats demonstrated a positive improved effect on the shinglet dry tensile strength (MD). As discussed above in Example 2, improvement in the tensile strength of the shingle will permit manufacturers to run their shingle production lines at a faster rate with less tearing or “break up” of the shingles. As a result, an increase in productivity may be achieved by the inclusion of a coupling agent or agents to the chopped strand mat during the wet-laid process.
The invention of this application has been described above both generically and with regard to specific embodiments. Although the invention has been set forth in what is believed to be the preferred embodiments, a wide variety of alternatives known to those of skill in the art can be selected within the generic disclosure, including by way of example, using this invention in the process of forming a continuous filament mat, a dry laid mat, or any other fibrous mat having a similar binder system. The invention is not otherwise limited, except for the recitation of the claims set forth below.
