Patent Application
20080289274
The present invention relates to stiff light weight panels, typically polymer composites. The panels are structurally rigid (stiff) and suitable for use in a number of applications such as a protective overlay (i.e. turf cover) for playing areas for arenas or stadiums and also for concrete forms. The panels have a sufficient stiffness (don't bend) for such applications. Depending on the composition of the matrix (e.g. metal, thermoset or thermoforming plastic) the panels may not have a suitable flexural and/or compressive strength to be load bearing. The panels are modular being made from two half panels which have a planar surface (e.g. flat or textured for grip) and on the back a number of ribs which define open faced closed wall cells and ribs which are not connected in a complimentary symmetrical arrangement so that when the half panels are placed back to back and rotated, typically through 180°, the panels may be fitted together so that the closed cells and ribs which are not interconnected fit together so that the cells have at least one diagonal member. Preferably, the half panels comprise a portion of the perimeter having an edge so that on joining the half panels together the outer perimeter is sealed. One advantage of this panel is that only one mold is needed to form the half panel.
A number of forms of double laminate structures are known. This includes the honeycomb structure typically in which two planar surfaces are adhered to opposite sides of a cellular honeycomb matrix. The double laminate structure also includes corrugated structures in which two planar surfaces are adhered to opposite sides of a central corrugated member (e.g. a cardboard type structure). Depending on the material of construction the laminate has reasonable compressive strength but doesn't have sufficient stiffness.
There are a number of patents in which there are layer structures having layers parallel to the top and bottom surface and parallel walls dividing the matrix into a number of parallel channels. Representative of this type of art are U.S. Pat. No. 5,348,790 issued Sep. 20, 1994 to Ben-Zev et al. assigned to Dan-Pal and U.S. Pat. No. 5,580,620 issued Dec. 3, 1996 assigned to 21st Century Limited. This art does not suggest the subject matter of the present invention. It teaches away from it as there are no transverse reinforcing members (cross braces) that could have easily been incorporated.
U.S. Pat. No. 5,970,899 issued Oct. 26, 1999 to Michaelson et al. assigned to the United States of America as represented by the Secretary of the Navy, discloses a crisscrossed latticed pattern for hatches in decks for container ships. The deck provides increased resistance to tension stress. The patent is of interest but fails to teach the interlocking half panels of the present invention.
U.S. Pat. No. 5,028,474 issued Jul. 2, 1991 to Czaplicki discloses a core of a laminate in which the core comprises continuous parallelograms defining alternating ridges and valleys in a cross pattern. The concept of the patent is similar to the honeycomb. The interior web is continuous and upper and lower surfaces are adhered to the web. This teaches away from the half panel of the present invention.
U.S. Pat. No. 5,958,551 issued Sep. 28, 1999 to Jorge-Isaac Garcia-Ochoa is in some senses similar to U.S. Pat. No. 5,028,474 except that the reinforcing matrix is not continuous. The matrix is in the form of truncated open pyramids with supports at the corners and a truncated or flattened top for attachment to a web or a further layer of reinforcing matrix. The patent teaches away from the present invention disclosure. The reinforcing parts do not interlock and further strengthen/stiffen each other. Also it fails to teach the half panel concept.
U.S. Pat. No. 4,348,442 issued Sep. 7, 1982 to Figge teaches a half panel comprising a web and integral truncated polyhedral (tetrahedral) elements. The polyhedral elements have a flattened surface for attachment to a second planar web. The patent does teach that the panels can be flipped over so that the polyhedrons on one face interlock (abut rather than interpenetrate) with those on the other face. The patent fails to teach different shapes or rotated interlocking/interpenetrating cells.
Applicant's co-pending U.S. patent application Ser. No. 11/435,329 filed May 16, 2006 discloses some of the polyolefin compositions which are useful in the present invention. However, the case does not disclose the specific cell structure of the present invention.
United States Patent Application 2006/0275600 published Dec. 7, 2006 discloses a double laminated sheet of plywood. The patent teaches that a relatively thin sheet of a polymer composite may be adhered to solid substrate such as metal or plywood to provide a sheet material suitable for use in pouring concrete. This is similar to the teachings of U.S. Pat. Nos. 5,537,797 and 5,836,126 issued Jul. 23, 1996 and Nov. 17, 1998 in the names of Harkenrider et al. assigned to The Salk Institute of Biological Studies which teach plywood having a polymer layer adhered to only one face of the plywood. These references teach away from the subject matter of the present patent application as they teach a solid substrate.
The half panels of the present invention have ribs defining (arrays of) open faced closed wall cells and cooperating (arrays) of ribs having spaces there between so that when the half panels are placed back to back and interlocked there is not only a perimeter defining the outside of the open faced closed wall cell but there is also at least one internal diagonal member within the cell.
The present invention seeks to provide a low cost (per use) structurally rigid panel typically for non-structural applications as plywood or composite board replacements such as turf covers and concrete forms.
In one aspect the present invention provides a modular half panel comprising a web having a planar upper surface having integrally on its back arrays of substantially vertical ribs of uniform depth defining open faced closed wall cells and cooperating arrays of ribs having spaces there between so when two half panels are placed back to back and rotated to align the cells and cooperating arrays of ribs having spaces there between the closed wall cells interlock and intersect with the cooperating arrays of ribs having spaces there between so that the closed wall cells have at least one reinforcing rib traversing said cell, said half panel further comprising two or more vertical side wall portions descending in the same direction and to the same depth as said ribs said side wall portions positioned on the periphery of said web so that when two half panels are interconnected the wall portions form a complete outer wall for the resulting panel.
The present invention further provides a process for forming a panel comprising fixing two half panels as described above, in back to back relationship so that the open faced closed wall cells on each half panel intersect and interlock with the ribs having spaces there between on the adjacent half panel .
In another aspect the present invention further provides a panel formed from two half panels as described above.
In a further aspect the present invention provides a light weight structurally rigid panel for use typically in non structural applications such as construction applications such as concrete forms and coverings for the floor of an arena or the field of a stadium (turf cover).
The present invention further provides a mold (die) having spaces defining a planar upper surface having integrally on its back arrays of substantially vertical ribs of uniform depth defining open faced closed wall cells and cooperating arrays of ribs having spaces there between, and two or more vertical side wall portions descending in the same direction and to the same depth as said ribs.
The present invention also distinguishes itself by only requiring a single mold or tooling design to form the key (half) panel component. Since tooling design and construction represents a substantial capital outlay, particularly for large panels, the use of a single mold or tooling design provides for significant cost reductions.
In the present specification unless otherwise specified weight % means weight % of the total composition of or used to form the half panel.
Complimentary symmetry means that for any (each) open faced closed wall cell on the back of a half panel there is at a symmetrical location through a plane (e.g. center line ) or through a point (center point) a complimentary series of ribs having spaces there between which will form one or more diagonal ribs of the closed wall open faced cell of a half panel rotated through an appropriate degree of rotation ( e.g. 180° for a rectangle and 90° for a square). This is illustrated by
The present invention relates to a half panel having a planar upper surface, either flat or textured and depending from the bottom a number of ribs which define open faced closed cells and ribs with spaces there between which provide diagonal reinforcement across the closed cells when two half panels are joined together in back to back relationship. The ribs, typically but not necessarily, are in continuous arrays arranged in complimentary symmetry. The arrays may for example cover diagonally opposed quarter sections of the half panel. The ribs could also be arranged so there are alternating ribs defining open faced closed wall cells with ribs having spaces there between provided in any row or column the number of closed wall cells and ribs having space there between are even. As a result when two panels are rotated through the appropriate degree of symmetry and placed back to back the cells will interlock and intersect with the ribs having spaces there between in such a manner that each open faced closed wall cell will have at least one transverse rib or member, typically a diagonal rib. The advantage of such a half panel is that only one mold is required to form two half panels which may be interconnected to form the complete panel. The half panel may be formed in any conventional manner including compression molding or injection molding.
Preferably the ribs are solid (continuous) but they could contain perforations (regions of voids or cut -outs to reduce weight). However, from the point of view of ease of mold manufacture and ease of ejecting parts from the mold preferably the ribs do not have “perforations”. The ribs have a substantially vertical axis having straight or tapered sides coming to a blunt or flat end (e.g. square ended) or possibly a “bull nose”, having equal beveled sides leading to the flat front, but preferably the end is rounded or is radiused. In a particularly preferred embodiment the ribs are tapered, narrowing towards the radiused upper edge. This embodiment makes it easier to remove the half panel from the mold.
The interlocking nature of the design allows the assembled panel to provide sufficient stiffness at a reduced overall thickness compared to a single sided panel. This in turn reduces the depth of the rib structures necessary to achieve specific modulus targets. Since the required rib depth is reduced, tooling costs associated with cutting deep rib structures into the mold are therefore lowered significantly
The open faced closed wall cells defined by the ribs may be of any shape provided the weight of the combined panel is not excessive for the application. Also the more intricate the shape of the cell the more costly the mold. For example the cell could be hexagonal and the ribs which have a space there between could define up to three cross members (e.g. a star of six points to fit into the corners of the hexagon cell). Preferably, the open faced closed wall cells are parallelograms, preferably rectangles or squares, of uniform size and the corresponding ribs having spaces there between may be in the form of a single cross member or a diagonal cross (e.g. triangles, scissors, or cells which are rotated relative to the closed wall open faced cells) or a six pointed star (or snowflake) for hexagons.
Typically the open faced closed wall cells may have a side length from about 2 inches (5 cm) to 12 inches (30.5 cm), preferably from about 6 inches (15.24 cm) to about 8 inches (20.32 cm). The ribs may have any height but typically are from a quarter of an inch (0.635 cm) to about two inches (5 cm), preferably from a half an inch (1.27 cm) to an inch (2.54 cm) most preferably from a half an inch (1.27 cm) to three quarters of an inch (1.905 cm) and a thickness from an eighth of an inch (0.32 cm) to a quarter of an inch (0.64 cm). The planar surface may have a thickness from an eighth of an inch (0.32 cm) to a quarter of an inch (0.64 cm).
In some cases the ribs having spaces there between may be in symmetrically opposed segments about the center point of said web, (typically quadrants) may be viewed as open walled open faced cells that are rotated at an angle from 30 to 90 degrees, preferably 30 to 45 degrees to the open faced closed wall cells in the adjacent quadrant.
Generally the half panel is also a parallelogram such as a square or a rectangle.
The half panel also has on its perimeter walls or edges descending an equal distance as the ribs at locations which are rotationally symmetrical relative to the half panel (preferably enclosing the array of open faced closed wall cells if they re in quadrants (see below)). In one embodiment the walls or edges descend at two adjacent sides of the half panel and extend along the perimeter of the panel for the full length of the panel edge. In an another embodiment the walls are at two opposed corners of the panel and extend along the perimeter of the panel for one half of length of the panel edge. For a square the sides or walls could be on opposite faces. This is a matter of ease of design and operation of the mold and assembly of the panels.
In one embodiment in the ribs having spaces there between further comprise contact members (tabs) descending from the web at locations which will contact corners of the closed wall cells. Generally these tabs are short members, typically from an inch (2.54 cm) to a half an inch (1.27 cm) typically about three quarters of an inch (1.905 cm) long, generally extending for the full height of the rib but possibly half or three quarter height of the rib could be used. If the half panels are glued or fused together the tabs provide points to glue or fuse the transverse ribs into the closed cell.
The half panels could be of any size but generally may have a length from 6 feet (1.83 meters) to 10 feet 3.02 meters, preferably 8 feet (2.44 meters) and a width from 2 feet (0.60 meters) to 6 feet (1.83 meters), preferably 4 feet (1.22 meters) by 8 feet (2.44 m)( e.g. plywood size). For some uses in the construction industry (e.g. concrete forms) the panel will preferably have a weight from about 70 to 85 pounds (31.75 kg to 38.6 kg) preferably from 70 to 80 pounds (31.75 kg to 36.28 kg) and a displacement under a 600 psf (pounds per square foot) force over a 16 inch span backed by 2×4 inch (5 cm ×10 cm) wood reinforcements at 16 inch centers of not more than 0.044 inches (0.111 cm), typically in the range from 0.021 inches (0.053 cm) to 0.014 inches (0.0356 cm).
The present invention will now be described with reference to
The half panel 1 comprises a back, web 2 from which a number of ribs 3 depend. The ribs 3 may be joined or continuous to define an open faced closed wall cell 4 or the ribs may be discontinuous having spaces 5 there between. In the figures the open faced closed wall cells 4 and the ribs having spaces there between define arrays symmetrically arranged (preferably rotationally symmetrically arranged) in quadrants about the center point of the half cell. The ribs 3 having spaces there between are positioned to engage the walls of the open faced closed wall cells 4 when two half panels are placed back to back and one of them is rotated through the rotational symmetry (in this case 180°). At the points of engagement of the ribs having spaces there between and the corners of the open faced closed wall cells there are tabs 6 on the ribs having spaces there between. Additionally the half panel has an edge 7 depending from the web or back 2 enclosing two symmetrically opposed quadrants of the half panel. In this case the quadrants of the half panel having open faced closed wall cells so that when two half panels are interlocked or in cooperating arrangement the resulting panel has an edge extending the full length around the panel. Preferably, but not necessarily the peripheral walls are in the portions (quadrants) of the half panel having the open faced closed wall cells. By doing this, one saves a little bit of weight, since an exterior edge on the open interlocking side would likely require that one of the closed cells from the opposite side would have be inserted along it. This would form a double thickness of material at each box wall-outer edge intersection. By placing the edge along the closed cell section, the outer wall is an integral part of the outer cell walls, thereby reducing the amount of material (and therefore the critical weight of assembled panel).
The panel of the present invention may be made from any suitable material such as metal or alloy. The metal or alloy comprises a light weight high tensile material. Typically the a metal or alloy comprises one or more metals selected from the group consisting of titanium, molybdenum, chromium, aluminum, magnesium, iron, nickel, and tungsten.
The half panel may be an organic material such as thermosetting resins or plastic (thermoset) or a thermoplastic resin.
Thermoset resins or plastics may be selected from the group consisting of unsaturated polyesters, phenolic resins, epoxide resins, polyimides and novolak resins, and urethane resins. The raw (uncompounded) thermoset resins or plastics will generally have a density from about 1.2 g/cc to about 1.6 g/cc. The web or matrix of the thermoset half panel may further optionally comprise from 0 to 40 weight % of one or more components selected from the group consisting of talc, calcium carbonate, silica, mica, wollastonite, hollow glass spheres and fibers selected from the group consisting of glass, polyester, polyamide, aramid and carbon fibers. Generally the fibers will have a nominal length of at least 0.5 cm, preferably 1.25 cm (½ inch) typically from about 2 to 25 cm. The fibers may have a diameter from about 10 to 20 μm, preferably from 10 to 15 μm, most preferably from 10 to 13 μm. The thermoset may optionally further comprise from 0 to 30 weight % of one or more flame retardants, heat and light stabilizers, and release agents. If the web or matrix of the thermoset half panel comprises fiber the thermoset may optionally further comprise from 0 to 10 weight % of a compatibilizer (as disclosed below).
The web or matrix of the half panel may be compression or injection moldable thermoplastic resin. The web of thermoplastic may optionally further comprise from 0 to 40, typically from 0.5 to 40 weight % of one or more components selected from the group consisting of talc, calcium carbonate, silica, mica, wollastonite, and hollow glass spheres. Generally the fibers will have a nominal length of at least 0.5 cm, preferably 1.25 cm (½ inch) typically from about 2 cm to 25 cm. The fibers may have a diameter from about 10 to 20 μm, preferably from 10 to 15 μm, most preferably from 10 to 13 μm. The thermoplastic may comprise from 0 to 30 weight % of one or more flame retardants, heat and light stabilizers, and release agents. If the web or matrix of the thermoplastic half panel comprises fiber the thermoplastic may optionally further comprise from 0 to 10 weight % of a compatibilizer.
The thermoplastic may be selected from the group consisting of polyamides, polyesters, polymers of one or more C2-8 olefins optionally further comprising from 0 to 50 weight % of one or more C3-6 ethylenically unsaturated carboxlic acids, anhydrides, amides, or nitriles, polymers of one or more C8-12 vinyl aromatic monomers optionally further comprising from 0 to 50 weight % of one or more C3-6 ethylenically unsaturated carboxlic acids, anhydrides, amides, or nitriles; polyacrylonitrile; polycarbonates; acetals; polyetherkeones; and polysulfones. In cases where there is concern about the toughness of the thermoplastic, the thermoplastic may further comprise from 5 to 30 weight % of a rubbery impact modifier. There are a number of patents assigned to E.I. Du Pont naming Bennett N. Epstein as inventor teaching toughening polyamides (e.g. nylon) or polyesters using toughening agents. Two patents which are particularly relevant are U.S. Pat. Nos. 4,172,859 and 4,174,358 issued Oct. 30, 1979 and Nov. 13, 1979 respectfully, the texts of which are herein incorporated by reference.
For polymers or copolymers of styrene, acrylonitrile and C1-4 alkyl esters of C3-6 ethylenically unsaturated carboxylic acids (e.g. acrylic acid and methacrylic acid) rubbery polymers which may be used may be selected from the group of polymers consisting of:
(i) homopolymers of C4-6 conjugated diolefins which are unsubstituted or substituted by a chlorine atom;
(ii) homogeneous homo- and copolymers of C4-8 alkyl esters of acrylic and methacrylic acid which homo- and copolymers have a Tg less than 20° C.;
(iii) heterogeneous polymers comprising 40 to 60 weight percent of a first domain comprising 100 to 70 weight percent of one or more C4-8 acrylate or methacrylate esters which form homopolymers having a Tg less than 020 C., and from 0 to 30 weight percent of one or more monomers selected from the group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate and ethyl methacrylate; and from 60 to 40 weight percent of a subsequent domain comprising a homopolymer or a copolymer of one or more monomers selected from the group consisting of methyl acrylate, ethyl acrylate, methyl methacrylate, and ethyl methacrylate;
(iv) linear and radial block copolymers having a molecular weight of at least 75,000 and a styrene content from 20 to 50 weight percent selected from the group consisting of styrene-butadiene diblock copolymers, styrene-butadiene-styrene triblock copolymers, styrene-isoprene diblock copolymers, styrene-isoprene-styrene triblock copolymers, partially hydrogenated styrene-butadiene-styrene triblock copolymers, and partially hydrogenated styrene-isoprene-styrene triblock copolymers; and
(v) copolymers comprising 100-60 weight percent of a C4-6 conjugated diolefin and 0-40 weight percent of one or more monomers selected from the group consisting of C2-6 alkenyl nitrile monomers, C8-12 vinyl aromatic monomers; C1-4 alkyl esters of acrylic acid; C1-4 esters of methacrylic acid.
The thermoplastic resins may be compounded in the same manner as the thermoset resins.
If fibers are present in the web or matrix of the half panel they may be present in amounts from 10 to 40, preferably from 20 to 40, most preferably from 25 to 40 weight % based on the weight of the thermoplastic (or thermoset) resin.
In compression molding one wouldn't expect any appreciable orientation of the fibers except for incidental orientation resulting from the direction of material flow. This situation produces panels with essentially anisotropic properties.
Alternately, in injection molding, one would expect a higher degree of fiber orientation, in part due to the higher shear rates typically experienced and dependent on the number of injection ports or gates in the mold. Injection molding may be used to produce panels with isotropic properties, i.e. to enhance physical properties in a particular direction. Preferably, the fibers will have a low degree, less than 25%, preferably less than 15%, most preferably less than 10% of orientation in the same direction. As a result the physical properties of the half panel when measured in different directions (e.g. the x, y, and z planes) are not the same.
In cases where the thermoplastic or thermoset resin has a low degree of adhesion to the fiber the thermoplastic or thermoset resin may, as noted above, further comprise a compatibiliser or adhesion promoter in amounts from 1 to 10 weight %, preferably from 2 to 8 weight %. Typically the compatibilizer or adhesion promoter comprises a polar polymer.
Some polar polymers which may be suitable as compatibilizers include polymers selected from the group consisting of homopolymers of one or more C3-6 ethylenically unsaturated carboxylic acids, anhydrides or amides; copolymers comprising from 5 to 95 weight % of one or more C3-6 ethylenically unsaturated carboxylic acids, anhydrides or amides and from 95 to 5 weight % of one or amides, esters, or C2-8 olefins and C2-8 polyolefins, which have been grafted with from 5 to 30 weight % of one or more C3-6 ethylenically unsaturated carboxylic acids, anhydrides or amides, polyesters which have been grafted with from 5 to 30 weight % of C3-6 ethylenically unsaturated carboxylic acids, anhydrides or amides and polyamides which have been grafted with from 5 to 30 weight % of C3-6 ethylenically unsaturated carboxylic acids or anhydrides.
The polar polymer may also be selected from (but not limited to) the following groups of polymers.
(i) Olefinic homopolymers and copolymers (e.g. polymers comprising from 90 to 100 weight % of ethylene and from 0 to 10 weight % of one or more C3-10, preferably C4-8 olefins, preferably alpha olefins) that have been modified through grafting with up to 10 weight %, preferably from 2 to 8 weight %, typically from 4 to 8 weight % of one or more C3-6 ethylenically unsaturated carboxylic acids, anhydrides and imides. Examples include, but are not limited to, so-called compatibilizers such as BYNEL® products (from DuPont Company) maleic anhydride modified polyolefins available under the POLYBOND® (Chemtura) product range.
(ii) Copolymers comprising from about 99 to 50 weight %, preferably from 99 to 80, typically from 95 to 80 of one or more C2-8 olefin monomers (e.g. ethylene) and which incorporate from 1 to 50 weight %, preferably from 1 to 20 weight %, typically from 5 to 20 weight % of one or more C3-8 ethylenically unsaturated polar monomers including but not limited to carboxylic acids, anhydrides, imides, glycidyl methacrylate and carboxylic acid derivatives, including vinyl acetate esters (ethylene vinyl acetate) and ionomers (alkali or alkali earth metal salts of acidic polymers ( e.g. ethylene acrylate salts).
In one embodiment the polar polymer is selected from the group consisting of glycidyl methacrylate, ionomers of 80 to 95 weight % of ethylene and 20 to 5 weight % of one or more C3-6 carboxylic acids; copolymers of 80 to 95 weight % of ethylene and 20 to 5 weight % of one or more C3-6 carboxylic acids, copolymers of 80 to 95 weight % of ethylene and 20 to 5 weight % of one or more anhydrides of C3-6 carboxylic acids and copolymers of 80 to 95 weight % of ethylene and 20 to 5 weight % of one or more imides of C3-6 carboxylic acids and ethylene vinyl acetate.
In one embodiment the thermoplastic resin may be selected from the group consisting of polyesters, polyamides, polyolefins, copolymers of styrene and maleic acid, copolymers of styrene and maleic anhydride (such as those sold by NOVA Chemicals Incorporated under the trademark DYLARK®), copolymers of styrene and maleimide, copolymers of styrene and acrylonitrile copolymers, styrene and acrylic acid or methacrylic acid, and polyacrylonitirle.
If the thermoplastic is a polyolefin preferably it has a density greater than 0.930 g/cc, preferably from 0.939 to 0.959 g/cc, most preferably from 0.945 to 0.959 g/cc. Typically the polymer comprises from 90, preferably 95, to 99.9 weight % of one or more C2-4 alpha olefin monomers and from 0.01 to 10, preferably 5 weight % of one or more C6-8 alpha olefin monomers. The polymer may comprise from 99 to 90 weight % of ethylene and from 1 to 10 weight % of one or more C3-8, preferably C 6-8 alpha olefins. Typically the polymer has a melt index (ASTM D1238, 2.16 kg, 190° C.) from 0.5 to 10 g/10 min, preferably from 2 to 8 g/10 min
The polyolefin may be made using gas phase, solution or slurry processes.
Solution and slurry polymerization processes are fairly well known in the art. These processes are conducted in the presence of an inert hydrocarbon solvent typically a C4-12 hydrocarbon which may be unsubstituted or substituted by a C1-4 alkyl group such as butane, pentane, hexane, heptane, octane, cyclohexane, methylcyclohexane or hydrogenated naphtha. An additional solvent is Isopar E (C8-12 aliphatic solvent, Exxon Chemical Co.).
The polymerization may be conducted at temperatures from about 20° C. to about 250° C. Depending on the product being made, this temperature may be relatively low such as from 20° C. to about 180° C., typically from about 80° C. to 150° C. and the polymer is insoluble in the liquid hydrocarbon phase (diluent) (e.g. a slurry polymerization). The reaction temperature may be relatively higher from about 180° C. to 250° C., preferably from about 180° C. to 230° C. and the polymer is soluble in the liquid hydrocarbon phase (solvent). The pressure of the reaction may be as high as about 15,000 psig for the older high pressure processes or may range from about 15 to 4,500 psig.
In the gas phase polymerization a gaseous mixture comprising from 0 to 15 mole % of hydrogen, monomers as noted above, and from 0 to 75 mole % of an inert gas at a temperature from 50° C. to 120° C., preferably from 75° C. to about 110° C., and at pressures typically not exceeding 3447 kPa (about 500 psi), preferably not greater than 2414 kPa (about 350 psi) is contacted with a supported catalyst as noted above and polymerized.
The catalyst may be a Ziegler Natta catalyst typically based on Ti and activated with a trialkyl aluminum (e.g. triethyl aluminum) or an alkyl aluminum alkoxide ( diethyl aluminum ethoxide) compound, a Phillips type catalyst based on Cr or it may be a single site catalyst.
If the process is a gas phase or slurry polymerization typically the catalyst is supported.
The catalyst system of the present invention may be supported on an inorganic or refractory support, including for example alumina, silica and clays or modified clays or an organic support (including polymeric support such as polystyrene or cross-linked polystyrene). The catalyst support may be a combination of the above components. However, preferably the catalyst is supported on an inorganic support or an organic support (e.g. polymeric) or mixed support. Some refractories include silica, which may be treated to reduce surface hydroxyl groups and alumina. The support or carrier may be a spray-dried silica. Generally the support will have an average particle size from about 0.1 to about 1,000, preferably from about 10 to 150 microns. The support typically will have a surface area of at least about 10 m2/g, preferably from about 150 to 1,500 m2/g. The pore volume of the support should be at least 0.2, preferably from about 0.3 to 5.0 ml/g.
Generally the refractory or inorganic support may be heated at a temperature of at least 200° C. for up to 24 hours, typically at a temperature from 500° C. to 800° C. for about 2 to 20, preferably 4 to 10 hours. The resulting support will be essentially free of adsorbed water (e.g. less than about 1 weight %) and may have a surface hydroxyl content from about 0.1 to 5 mmol/g of support, preferably from 0.5 to 3 mmol/g.
A silica suitable for use in the present invention has a high surface area and is amorphous. For example, commercially available silicas are marketed under the trademark of Sylopol® 958 and 955 by Davison Catalysts, a Division of W. R. Grace, and Company and ES-70W sold by Ineos Silica.
The amount of the hydroxyl groups in silica may be determined according to the method disclosed by J. B. Peri and A. L. Hensley, Jr., in J. Phys. Chem., 72 (8), 2926, 1968, the entire contents of which are incorporated herein by reference.
While heating is the most preferred means of removing OH groups inherently present in many carriers, such as silica, the OH groups may also be removed by other removal means, such as chemical means. For example, a desired proportion of OH groups may be reacted with a suitable chemical agent, such as a hydroxyl reactive aluminum compound (e.g. triethyl aluminum) or a silane compound. This method of treatment has been disclosed in the literature and two relevant examples are: U.S. Pat. No. 4,719,193 to Levine in 1988 and by Noshay A. and Karol F. J. in Transition Metal Catalyzed Polymerizations, Ed. R. Quirk, 396, 1989. For example the support may be treated with an aluminum compound of the formula Al((O)aR1)bX3-b wherein a is either 0 or 1, b is an integer from 0 to 3, R1 is a C1-8 alkyl radical, and X is a chlorine atom. The amount of aluminum compound is such that the amount of aluminum on the support prior to adding the remaining catalyst components will be from about 0 to 2.5 weight %, preferably from 0 to 2.0 weight % based on the weight of the support.
The clay type supports are also preferably treated to reduce adsorbed water and surface hydroxyl groups. However, the clays may be further subject to an ion exchange process, which may tend to increase the separation or distance between the adjacent layers of the clay structure.
The polymeric support may be cross linked polystyrene containing up to about 50 weight %, preferably not more than 25 weight %, most preferably less than 10 weight % of a cross linking agent such as divinyl benzene.
In one embodiment of the invention the catalyst is a single site catalyst of the formula (selected from the group consisting of):
(L)n−M−(Y)p
wherein M is selected from the group consisting of Ti, Zr, and Hf; L is a monoanionic ligand independently selected from the group consisting of cyclopentadienyl-type ligands, and a bulky heteroatom ligand containing not less than five atoms in total of which at least 20%, numerically are carbon atoms and further containing at least one heteroatom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and silicon said bulky heteroatom ligand being sigma or pi-bonded to M; Y is independently selected for the group consisting of activatable ligands; n may be from 1 to 3; and p may be from 1 to 3, provided that the sum of n+p equals the valence state of. M, and further provided that two L ligands may be bridged, and an activator.
The polymer is prepared in the presence of a single site catalyst.
In one embodiment, the single site catalyst may be a metallocene type catalyst wherein L is a cyclopentadienyl type ligand and n, may be from 1 to 3, preferably 2.
The cyclopentadienyl-type ligand is a C5-13 ligand containing a 5-membered carbon ring having delocalized bonding within the ring and bound to the metal atom (i.e. the active catalyst metal or site) through η5 bonds and said ligand being unsubstituted or up to fully substituted with one or more substituents selected from the group consisting of C1-10 hydrocarbyl radicals in which hydrocarbyl substituents are unsubstituted or further substituted by one or more substituents selected from the group consisting of a halogen atom and a C1-8 alkyl radical; a halogen atom; a C1-8 alkoxy radical; a C6-10 aryl or aryloxy radical; an amido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; a phosphido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; silyl radicals of the formula —Si—(R)3 wherein each R is independently selected from the group consisting of hydrogen, a C1-8 alkyl or alkoxy radical, and C6-10 aryl or aryloxy radicals; and germanyl radicals of the formula Ge—(R)3 wherein R is as defined above. Preferably the cyclopentadienyl ligand (Cp) is independently selected from the group consisting of a cyclopentadienyl radical, an indenyl radical and a fluorenyl radical.
In the single site type catalyst two cyclopentadienyl ligand may be bridged or joined. If two cyclopentadienyl ligands are bridged or joined together the catalyst may be a constrained geometry catalyst. Non-limiting examples of bridging group include bridging groups containing at least one Group 13 to 16 atom, often referred to a divalent moiety such as but not limited to at least one of a carbon, oxygen, nitrogen, silicon, boron, germanium and tin atom or a combination thereof. Preferably, the bridging group contains a carbon, silicon or germanium atom, most preferably at least one silicon atom or at least one carbon atom. The bridging group may also contain substituent radicals as defined above including halogens.
Some bridging groups include but are not limited to, a di C1-6 alkyl radical (e.g. alkylene radical for example an ethylene bridge), di C6-10 aryl radical (e.g. a benzyl radical having two bonding positions available), silicon or germanium radicals substituted by one or more radicals selected from the group consisting of C1-6 alkyl, C6-10 aryl, phosphine or amine radical which are unsubstituted or up to fully substituted by one or more C1-6 alkyl or C6-10 aryl radicals, or a hydrocarbyl radical such as a C1-6 alkyl radical or a C6-10 arylene (e.g. divalent aryl radicals); divalent C1-6 alkoxide radicals (e.g. —CH2CHOH CH2—) and the like.
Exemplary of the silyl species of bridging groups are dimethylsilyl, methylphenylsilyl, diethylsilyl, ethylphenylsilyl, diphenylsilyl bridged compounds. Most preferred of the bridged species are dimethylsilyl, diethylsilyl and methylphenylsilyl bridged compounds.
Exemplary hydrocarbyl radicals for bridging groups include methylene, ethylene, propylene, butylene, phenylene and the like, with methylene being preferred.
Exemplary bridging amides include dimethylamide, diethylamide, methylethylamide, di-t-butylamide, diisopropylamide and the like.
The activatable ligands (Y) may be independently selected from the group consisting of a hydrogen atom; a halogen atom, a C1-10 hydrocarbyl radical; a C1-10 alkoxy radical; a C5-10 aryl oxide radical; each of which said hydrocarbyl, alkoxy, and aryl oxide radicals may be unsubstituted by or further substituted by one or more substituents selected from the group consisting of a halogen atom; a C1-8 alkyl radical; a C1-8 alkoxy radical; a C6-10 aryl or aryloxy radical; an amido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals; and a phosphido radical which is unsubstituted or substituted by up to two C1-8 alkyl radicals. Preferably Y is independently selected from the group consisting of a hydrogen atom, a chlorine atom and a C1-4 alkyl radical.
In one embodiment of the invention the catalyst may contain a bulky heteroatom ligand. The bulky heteroatom ligand is selected from the group consisting of phosphinimine ligands, ketimide ligands, silicon-containing heteroatom ligands, amido ligands, alkoxy ligands, boron heterocyclic ligands and phosphole ligands.
If the catalyst contains one or more bulky heteroatom ligands the catalyst would have the formula:
wherein M is a transition metal selected from the group consisting of Ti, Hf and Zr; D is independently a bulky heteroatom ligand (as described below); L is a monoanionic ligand selected from the group consisting of cyclopentadienyl-type ligands; Y is independently selected from the group consisting of activatable ligands; m is 1 or 2; n is 0 or 1; and p is an integer and the sum of m+n+p equals the valence state of M, provided that when m is 2, D may be the same or different bulky heteroatom ligands.
Bulky heteroatom ligands (D) include but are not limited to phosphinimine ligands and ketimide (ketimine) ligands.
In a further embodiment, the catalyst may contain one or two phosphinimine ligands (PI) which are bonded to the metal and the second catalyst has the formula
wherein M is a group 4 metal; PI is a phosphinimine ligand; L is a monoanionic ligand selected from the group consisting of a cyclopentadienyl-type ligand; Y is independently selected from the group consisting of activatable ligands; m is 1 or 2; n is 0 or 1; p is an integer and the sum of m+n+p equals the valence state of M.
The phosphinimine ligand is defined by the formula:
wherein each R21 is independently selected from the group consisting of a hydrogen atom; a halogen atom; C1-20, preferably C1-10 hydrocarbyl radicals which are unsubstituted by or further substituted by a halogen atom; a C1-8 alkoxy radical; a C6-10 aryl or aryloxy radical; an amido radical; a silyl radical of the formula:
—Si—(R22)3
wherein each R22 is independently selected from the group consisting of hydrogen, a C1-8 alkyl or alkoxy radical, and C6-10 aryl or aryloxy radicals; and a germanyl radical of the formula:
—Ge—(R22)3
wherein R22 is as defined above.
The preferred phosphinimines are those in which each R21 is a hydrocarbyl radical, preferably a C1-6 hydrocarbyl radical.
Suitable phosphinimine catalysts are Group 4 organometallic complexes which contain one phosphinimine ligand (as described above) and one ligand L which is either a cyclopentadienyl-type ligand or a heteroatom ligand.
As used herein, the term “ketimide ligand” refers to a ligand which:
(a) is bonded to the transition metal via a metal-nitrogen atom bond;
(b) has a single substituent on the nitrogen atom (where this single substituent is a carbon atom which is doubly bonded to the N atom); and
(c) has two substituents Sub 1 and Sub 2 (described below) which are bonded to the carbon atom.
Conditions a, b and c are illustrated below:
The substituents “Sub 1” and “Sub 2” may be the same or different. Exemplary substituents include hydrocarbyl radicals having from 1 to 20, preferably from 3 to 6, carbon atoms, silyl groups (as described below), amido groups (as described below) and phosphido groups (as described below). For reasons of cost and convenience it is preferred that these substituents both be hydrocarbyls, especially simple alkyls and most preferably tertiary butyl. “Sub 1” and “Sub 2” may be the same or different and can be bonded to each other to form a ring.
Suitable ketimide catalysts are Group 4 organometallic complexes which contain one ketimide ligand (as described above) and one ligand L which is either a cyclopentadienyl-type ligand or a heteroatom ligand.
The term bulky heteroatom ligand (D) is not limited to phosphinimine or ketimide ligands and includes ligands which contain at least one heteroatom selected from the group consisting of boron, nitrogen, oxygen, phosphorus, sulfur and silicon. The heteroatom ligand may be sigma or pi-bonded to the metal. Exemplary heteroatom ligands include silicon-containing heteroatom ligands, amido ligands, alkoxy ligands, boron heterocyclic ligands and phosphole ligands, as all described below.
Silicon containing heteroatom ligands are defined by the formula:
—(Y)SiRxRyRz
wherein the—denotes a bond to the transition metal and Y is sulfur or oxygen.
The substituents on the Si atom, namely Rx, Ry and Rz are required in order to satisfy the bonding orbital of the Si atom. The use of any particular substituent Rx, Ry or Rz is not especially important to the success of this invention. It is preferred that each of Rx, Ry and Rz is a C1-2 hydrocarbyl group (i.e. methyl or ethyl) simply because such materials are readily synthesized from commercially available materials.
The term “amido” is meant to convey its broad, conventional meaning. Thus, these ligands are characterized by (a) a metal-nitrogen bond; and (b) the presence of two substituents (which are typically simple alkyl or silyl groups) on the nitrogen atom.
The terms “alkoxy”and “aryloxy” is also intended to convey its conventional meaning. Thus, these ligands are characterized by (a) a metal oxygen bond; and (b) the presence of a hydrocarbyl group bonded to the oxygen atom. The hydrocarbyl group may be a C1-10 straight chained, branched or cyclic alkyl radical or a C6-13 aromatic radical where the radicals are unsubstituted or further substituted by one or more C1-4 alkyl radicals (e.g. 2,6 di-tertiary butyl phenoxy).
Boron heterocyclic ligands are characterized by the presence of a boron atom in a closed ring ligand. This definition includes heterocyclic ligands which also contain a nitrogen atom in the ring. These ligands are well known to those skilled in the art of olefin polymerization and are fully described in the literature (see, for example, U.S. Pat. Nos. 5,637,659; 5,554,775; and the references cited therein).
The term “phosphole” is also meant to convey its conventional meaning. “Phospholes” are cyclic dienyl structures having four carbon atoms and one phosphorus atom in the closed ring. The simplest phosphole is C4PH4 (which is analogous to cyclopentadiene with one carbon in the ring being replaced by phosphorus). The phosphole ligands may be substituted with, for example, C1-20 hydrocarbyl radicals (which may, optionally, contain halogen substituents); phosphido radicals; amido radicals; or silyl or alkoxy radicals. Phosphole ligands are also well known to those skilled in the art of olefin polymerization and are described as such in U.S. Pat. No. 5,434,116 (Sone, to Tosoh).
In one embodiment the catalyst may contain no phosphinimine ligands as the bulky heteroatom ligand. The bulky heteroatom containing ligand may be selected from the group consisting of ketimide ligands, silicon-containing heteroatom ligands, amido ligands, alkoxy ligands, boron heterocyclic ligands and phosphole ligands. In such catalysts the Cp ligand may be present or absent.
The preferred metals (M) are from Group 4 (especially titanium, hafnium or zirconium), with titanium being most preferred.
The catalysts in accordance with the present invention may be activated with an activator selected from the group consisting of:
(i) a complex aluminum compound of the formula R122AlO(R12AlO)mAlR122 wherein each R12 is independently selected from the group consisting of C1-20 hydrocarbyl radicals and m is from 3 to 50, and optionally a hindered phenol to provide a molar ratio of Al:hindered phenol from 2:1 to 5:1 if the hindered phenol is present;
(ii) ionic activators selected from the group consisting of:
(iii) mixtures of (i) and (ii).
Preferably the activator is a complex aluminum compound of the formula R122AlO(R12AlO(R12AlO)mAlR 122 wherein each R12 is independently selected from the group consisting of C1-20 hydrocarbyl radicals and m is from 3 to 50, and optionally a hindered phenol to provide a molar ratio of Al:hindered phenol from 2:1 to 5:1 if the hindered phenol is present. In the aluminum compound preferably, R12 is methyl radical and m is from 10 to 40. The preferred molar ratio of Al:hindered phenol, if it is pr 3.25:1 to 4.50:1. Preferably the phenol is substituted in the 2, 4 and 6 position by a C2-6 alkyl radical. Desirably the hindered phenol is 2,6-di-tert-butyl-4-ethyl-phenol.
The aluminum compounds (alumoxanes and optionally hindered phenol) are typically used as activators in substantial molar excess compared to the amount of metal in the catalyst. Aluminum:transition metal molar ratios of from 10:1 to 10,000:1 are preferred, most preferably 10:1 to 500:1 especially from 40:1 to 120:1.
Ionic activators are well known to those skilled in the art. The “ionic activator” may abstract one activatable ligand so as to ionize the catalyst center into a cation, but not to covalently bond with the catalyst and to provide sufficient distance between the catalyst and the ionizing activator to permit a polymerizable olefin to enter the resulting active site.
Examples of ionic activators include:
Readily commercially available ionic activators include:
Ionic activators may also have an anion containing at least one group comprising an active hydrogen or at least one of any substituent able to react with the support. As a result of these reactive substituents, the ionic portion of these ionic activators may become bonded to the support under suitable conditions. One non-limiting example includes ionic activators with tris(pentafluorophenyl)(4-hydroxyphenyl)borate as the anion. These tethered ionic activators are more fully described in U.S. Pat. Nos. 5,834,393; 5,783,512; and 6,087,293.
It has been well recognized that a semi-crystalline polyethylene resin consists of at least three phases, i.e., crystalline, amorphous and interfacial phases. The amount of interfacial phase actually contains the contribution of tie chains which has long been known as one of the key fundamental resin parameters in determining many polyethylene product properties such as toughness, environmental stress cracking resistance, etc. The amount of interfacial phase can be used as an indication of the amount of tie chains. Hence, within the same resin category (e.g., HDPE or MDPE), a resin with the higher amount of interfacial phase would typically be expected to provide a higher toughness than another with a lower amount of interfacial phase, either alone or in a system such as composites. The single sited catalyzed polyethylenes of the present invention have a higher amount of polymer in the interfacial phase between the crystalline phase and the amorphous phase and as such have a higher degree of tie chains between these phases in the polymer. The increase in the amount of interfacial phase in the single site catalysed (SSC) polyethylenes over those of comparable, conventional Ziegler-Natta catalyzed polyethylenes (e.g. comparable polyethylenes having a composition within 5 weight %, preferably within 2 weight % of the single site catalysed polyethylene, density within 0.005 g/cm3 of the single site catalysed polyethylene, and a melt index within 0.5 g/10 min, preferably 0.2 g/10 min. of the single site catalysed polyethylene) may range from about 1.5 to 7 weight %, preferably from about 2 to 6 weight % as inferred using Raman spectroscopy (using a 514.5 nm laser Raman Spectroscopy).
The polymers used to make the half panel may be compounded in any conventional manner known to those skilled in the art such as dry blending (e.g. tumble blending ) or melt blending (e.g. extrusion blending). The resulting blend may then be injection or compression molded to form the half panel. The conditions of these processes are well known to those skilled in the art.
There are several types of compression molding processes. In one process a pre-impregnated composite of long or chopped glass fiber randomly oriented is prepared in a sheet form and put into a suitable mold and the polyolefin composite (e.g. polyethylene composition) is then injected into the mold. When the mold cools a solid sheet is formed. Another compression process uses a low shear screw in an injection machine to deliver the polymer fiber, preferably glass, composition into half of a compression mold and the other half of the mold is applied in a separate step. Preferably the injection machine is fitted with a low shear screw or screw having a distance between adjacent flights on the screw greater than the desired length of the fiber used to reinforce the composite. This tends to reduce fiber length attrition. Preferably the forming process (extrusion, etc.) is such that fiber length attrition (loss of initial fiber length in the feed to the molding machine measured by comparing the fiber length in the molded part versus the fiber length fed to the extruder) is less than 30%, preferably less than 20%, most preferably less than 15%.
As noted above the resulting half panels may then be rotated through the axis of symmetry (e.g. such as 180° for rectangles) and placed back to pack and fixed together. The half panels may be glued together or heat welded together. Some commercially available glues which may be useful include GLUCO®, BONDUIT®, GORILLA GLUE®, ScotchWeld® DP8005, 3M® 4932, 3M® 4085, 3M® 9495LE etc.
In one application the full panels may be used to replace plywood in a number of applications such as forms to pour concrete. The supports or bracing for such forms typically comprise 2×4 inch (5 cm ×10 cm) boards in a frame structure typically having 18 inch (45.7 cm) vertical centers.
The present invention will now be illustrated by the following non-limiting example.
Applicants collected data for the deflection of ¾ inch plywood under a force of 600 psf when the plywood is in a frame having 2″×4″ reinforcements on 16 inch centers. Using this data the modulus for plywood was determined to be 1.1×106 psi. Using this modulus a maximum deflection in the center between 16 inch center 2″×4″ framework of a piece of plywood under a force of 600 pounds per square foot was calculated to be 0.0085 inches.
Using this data and assuming a modulus of 1.1×106 psi and a deflection of 1/360 inches over a 16 inch reinforced span various models of a panel according to the present invention with a cell structure as shown in
The data shows that the panels are competitive with plywood. In field trials it was noted the panels of the invention do not adsorb water to anywhere near the extent of plywood so a good comparison for weight is towards the 80 lbs per sheet. The panels release well from the mold and appear on average to be capable of more uses per sheet than plywood reducing the cost per pour of concrete.
