WO2008124810A1 - Foam articles and methods of producing the same - Google Patents

Abstract

A method for producing a foam sheet comprises: forming a foamed material, casting the foamed material, impinging the cast material with a fluid at a sufficient pressure to form a hole, and curing the impinged material. If the foamed material comprises a thermoset, the foamed material is uncured or partially cured. If the foamed material comprises a thermoplastic, the foamed material is unset or partially set. A foam sheet comprises: a first surface and an opposite second surface, and a plurality of holes extending through the first surface toward the second surface. The holes comprise a skin cover, the holes having a conical geometry, and/or each of the holes has a diameter larger than the largest pore diameter of the foam, as well as combinations comprising at least one of the foregoing characteristics.

Description

FOAM ARTICLES AND METHODS OF PRODUCING THE SAME

CROSS-REFERENCE TO RELATED APPLICATIONS

[0001] This application claims the benefit of U.S. Provisional Application Serial No. 60/910,986 filed April 10, 2007, which is incorporated herein by reference in its entirety.

BACKGROUND

[0002] Disclosed herein are foam articles and methods for making the same.

[0003] Polyurethane foams, for example, are used in a wide variety of applications, from automotive seats to carpet backing. Polyurethane foam sheets have many advantageous properties that would be useful in a footwear article, e.g., in the upper structure. An article of footwear generally includes an upper and a sole structure. The upper comfortably receives a foot and secures the foot to the sole structure. The sole structure provides a durable medium for supporting the foot and may include multiple elements. Modern footwear is a combination of many elements that have specific functions, all of which must work together for the support and protection of the foot as well as for aesthetics.

[0004] It is desirable to produce polyurethane foam articles having indentations into the foam ("holes"), and in some instances, openings through the foam ("thru-holes"), for functional and/or aesthetic purposes. However, forming holes into and/or through the foam without producing substantial amounts of waste and/or substantially complicating the foam sheet production process is a large challenge. Indentations and/or through holes can be formed using a hole punch, but results in material waste that increases the cost of the foam and must be disposed of, as well as creating exposed cells. The exposed cells can change the appearance of the foam articles, such as, for example, color differences between the exposed cells and the foam surface. Moreover, the exposed cells can affect the washability of the article, because the exposed foam cells could absorb liquids and potentially change the article properties. Indentations and/or through holes can also be provided using the appropriate molds, but producing such molds is expensive, and once produced, cannot be altered to provide different sizes or patterns of indentations or through- holes.

[0005] Soft foam articles and methods for making the foam article wherein the articles have holes formed into and/or through the article are sought-after.

SUMMARY

[0006] Disclosed herein are foam articles and methods for making the same.

[0007] In one embodiment, a method for producing polyurethane foam sheet comprises: frothing a polyurethane-forming composition, casting the frothed reactive polyurethane-forming composition onto a first carrier to form a sheet, impinging the sheet with a fluid at a sufficient pressure to form a hole, and curing the frothed reactive polyurethane-forming composition to form a sheet comprising a hole. The polyurethane-forming composition can comprise an isocyanate-containing component, an active hydrogen-containing component reactive with the isocyanate- containing component, a surfactant, and catalyst system.

[0008] In another embodiment, a method for producing a foam sheet comprises: forming a foamed material, casting the foamed material onto a first carrier, impinging the cast material with a fluid at a sufficient pressure to form a hole, and curing the impinged material to form a sheet comprising the hole. If the foamed material comprises a thermoset, the foamed material is uncured or partially cured. If the foamed material comprises a thermoplastic, the foamed material is unset or partially set, and can further require a cooling step.

[0009] In one embodiment, a foam sheet comprises: a first surface and an opposite second surface, and a plurality of holes extending through the first surface toward the second surface. The holes can have a characteristic selected from the group consisting of a skin cover, a conical geometry, a diameter at least two times larger than the largest pore diameter of the foam, and combinations comprising at least one of the foregoing characteristics.

[0010] The above described and other features are exemplified by the following figures and detailed description. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Refer now to the figures, which are exemplary and not limiting, and wherein like elements are numbered alike.

[0012] Figures 1 - 4 are schematic drawings of exemplary foamed sheets having holes formed into and/or through the foam.

[0013] Figure 5 is a schematic cross-sectional view of exemplary foam sheets manufactured as described herein.

DETAILED DESCRIPTION

[0014] Foam articles (e.g., foam sheets that can be used in various applications including footwear, and others) can be produced with a desired hole distribution, geometry, and depth, by using fluid jet(s) in the foam sheet production process. The fluid jets can be used before, during, and/or after partial curing/solidification of the foam. Additionally, nozzle sizes, geometries, and fluid pressures can be adjusted and/or controlled to produce a hole pattern, hole design, and/or hole geometry(ies), and to attain a desired structural integrity and/or aesthetics.

[0015] The foams can be manufactured mechanically and/or chemically (e.g., by physical blowing (e.g., mechanically frothing), chemical blowing, as well as combinations comprising at least one of the foregoing). For example, a polymer mixture (comprising an isocyanate component, an active hydrogen-containing component, and other additives), can be mechanically frothed followed by curing. The foams can be formed into sheets by casting.

[0016] The foam sheet can be formed from various foams (e.g., open cell or closed cell) such as thermoplastic foams and/or thermoset foams. Some possible foams include silicone, polyurethane, polyolefin (e.g., polyethylene, low density polyethylene, high density polyethylene, polypropylene, ethylene-propylene copolymers, and so forth), polyesters, polyamides, fluorinated polymers, polyalkylene oxides (e.g., polyethylene oxide and polypropylene oxide), polyvinyl alcohol, ionomers (e.g., ethylene-methacrylic acid copolymers neutralized with base), cellulose acetate, polystyrene, and so forth, as well as combinations comprising at least one of the foregoing.

[0017] Polymers for use in the foams can be selected from a wide variety of thermoplastic resins, blends of thermoplastic resins, or thermosetting resins. Examples of thermoplastic resins that can be used include polyacetals, polyacrylics, styrene acrylonitrile, polyolefins, acrylonitrile-butadiene-styrene, polycarbonates, polystyrenes, polyethylene terephthalates, polybutylene terephthalates, polyamides such as, but not limited to Nylon 6, Nylon 6,6, Nylon 6,10, Nylon 6,12, Nylon 11 or Nylon 12, polyamideimides, polyarylates, polyurethanes, ethylene propylene rubbers (EPR), polyarylsulfones, polyethersulfones, polyphenylene sulfides, polyvinyl chlorides, polysulfones, polyetherimides, polytetrafluoroethylenes, fluorinated ethylene propylenes, polychlorotrifluoroethylenes, polyvinylidene fluorides, polyvinyl fluorides, polyetherketones, polyether etherketones, polyether ketone, ketones, and the like, or a combination comprising at least one of the foregoing thermoplastic resins.

[0018] Examples of blends of thermoplastic resins that can be used in the polymer foams include acrylonitrile-butadiene-styrene/nylon, polycarbonate/acrylonitrile-butadiene-styrene, acrylonitrile butadiene styrene/polyvinyl chloride, polyphenylene ether/polystyrene, polyphenylene ether/nylon, polysulfone/acrylonitrile-butadiene-styrene, polycarbonate/thermoplastic urethane, polycarbonate/polyethylene terephthalate, polycarbonate/polybutylene terephthalate, thermoplastic elastomer alloys, polyethylene terephthalate/polybutylene terephthalate, styrene-maleic anhydride/acrylonitrile-butadiene-styrene, polyether etherketone/polyethersulfone, styrene-butadiene rubber, polyethylene/nylon, polyethylene/polyacetal, ethylene propylene rubber (EPR), and the like, or a combination comprising at least one of the foregoing blends.

[0019] Examples of polymeric thermosetting resins that can be used in the polymer foams include polyurethanes, epoxys, phenolics, polyesters, polyamides, silicones, and the like, or a combination comprising at least one of the foregoing thermosetting resins. Blends of thermosetting resins as well as blends of thermoplastic resins with thermosetting resins can be used. [0020] Other additives known for use in the manufacture of foams can be present in the foam compositions, for example other fillers, such as reinforcing fillers such as woven webs, silica, glass particles, and glass microballoons, fillers used to provide thermal management, or flame retardant fillers or additives. Suitable flame retardants include, for example, a metal hydroxide containing aluminum, magnesium, zinc, boron, calcium, nickel, cobalt, tin, molybdenum, copper, iron, titanium, or a combination thereof, for example aluminum trihydroxide, magnesium hydroxide, calcium hydroxide, iron hydroxide, and the like; a metal oxide such as antimony oxide, antimony trioxide, antimony pentoxide, iron oxide, titanium oxide, manganese oxide, magnesium oxide, zirconium oxide, zinc oxide, molybdenum oxide, cobalt oxide, bismuth oxide, chromium oxide, tin oxide, nickel oxide, copper oxide, tungsten oxide, and the like; metal borates such as zinc borate, zinc metaborate, barium metaborate, and the like; metal carbonates such as zinc carbonate, magnesium carbonate, calcium carbonate, barium carbonate, and the like; melaniine cyanurate, melamine phosphate, and the like; carbon black, expandable graphite flakes (for example those available from GrafTech International, Ltd. under the tradename GRAFGUARD), and the like; nanoclays; and brominated compounds. Exemplary flame retardant materials are magnesium hydroxides, nanoclays, and brominated compounds, hi one embodiment, flame retardance of the polymer foam meets certain Underwriter's Laboratories (UL) standards for flame retardance. For example, the polymer foam has a rating of V-O under UL Standard 94.

[0021] Still other additives that can be present include dyes, pigments (for example titanium dioxide and iron oxide), antioxidants, antiozonants, ultraviolet (UV) stabilizers, conductive fillers, catalysts for cure of the polymer, crosslinking agents, and the like, as well as combinations comprising at least one of the foregoing additives.

[0022] Specific polymers for use in the manufacture of the foams include polyurethane foams and silicone foams. For example, in general, polyurethane foams are formed from reactive compositions comprising an organic isocyanate component reactive with an active hydrogen-containing component(s), a surfactant, and a catalyst. The organic isocyanate components used in the preparation of polyurethane foams generally comprises polyisocyanates having the general formula Q(NCO),, wherein "i" is an integer having an average value of greater than two, and Q is an organic radical having a valence of "i". Q can be a substituted or unsubstituted hydrocarbon group (e.g., an alkane or an aromatic group of the appropriate valency). Q can be a group having the formula Q¹ -Z-Q¹ wherein Q¹ is an alkylene or arylene group and Z is -O-, -O-Q^S, -CO-, -S-, -S-Q^S-, -SO- or -SO₂-. Exemplary isocyanates include hexamethylene diisocyanate, 1,8-diisocyanato-p-methane, xylyl diisocyanate, diisocyanatocyclohexane, phenylene diisocyanates, tolylene diisocyanates, including 2,4-tolylene diisocyanate, 2,6-tolylene diisocyanate, and crude tolylene diisocyanate, bis(4-isocyanatophenyl)methane, chlorophenylene diisocyanates, diphenylmethane-4,4'-diisocyanate (also known as 4,4'-diphenyl methane diisocyanate, or MDI) and adducts thereof, naphthalene-l,5-diisocyanate, triphenylmethane-4,4',4"-triisocyanate, isopropylbenzene-alpha-4-diisocyanate, polymeric isocyanates such as polymethylene polyphenylisocyanate, and combinations comprising at least one of the foregoing isocyanates.

[0023] Q can also represent a polyurethane radical having a valence of "i", in which case Q(NCO), is a composition known as a prepolymer. Such prepolymers are formed by reacting a stoichiometric excess of a polyisocyanate as set forth hereinbefore and hereinafter with an active hydrogen-containing component as set forth hereinafter, especially the polyhydroxyl-contaming materials or polyols described below. Usually, for example, the polyisocyanate is employed in proportions of about 30 percent to about 200 percent stoichiometric excess, the stoichiometry being based upon equivalents of isocyanate group per equivalent of hydroxyl in the polyol. The amount of polyisocyanate employed will vary slightly depending upon the nature of the polyurethane being prepared.

[0024] The active hydrogen-containing component can comprise polyether polyols and polyester polyols. Exemplary polyester polyols are inclusive of polycondensation products of polyols with dicarboxylic acids or ester-forming derivatives thereof (such as anhydrides, esters and halides), polylactone polyols obtainable by ring-opening polymerization of lactones in the presence of polyols, polycarbonate polyols obtainable by reaction of carbonate diesters with polyols, and castor oil polyols. Exemplary dicarboxylic acids and derivatives of dicarboxylic acids which are useful for producing polycondensation polyester polyols are aliphatic or cycloaliphatic dicarboxylic acids such as glutaric, adipic, sebacic, fumaric and maleic acids; dimeric acids; aromatic dicarboxylic acids such as phthalic, isophthalic and terephthalic acids; tribasic or higher functional polycarboxylic acids such as pyromellitic acid; as well as anhydrides and second alkyl esters, such as maleic anhydride, phthalic anhydride and dimethyl terephthalate.

[0025] Additional active hydrogen-containing components are the polymers of cyclic esters. The preparation of cyclic ester polymers from at least one cyclic ester monomer is well documented in the patent literature as exemplified by U.S. Patent Nos. 3,021,309 through 3,021,317; 3,169,945; and 2,962,524. Exemplary cyclic ester monomers include δ-valerolactone; e-caprolactone; zeta-enantholactone; and the monoalkyl-valerolactones (e.g., the monomethyl-, monoethyl-, and monohexyl- valerolactones). hi general the polyester polyol can comprise caprolactone based polyester polyols, aromatic polyester polyols, ethylene glycol adipate based polyols, and combinations comprising at least one of the foregoing polyester polyols, and especially polyester polyols made from e-caprolactones, adipic acid, phthalic anhydride, terephthalic acid and/or dimethyl esters of terephthalic acid.

[0026] The polyether polyols are obtained by the chemical addition of alkylene oxides (such as ethylene oxide, propylene oxide, and so forth, as well as combinations comprising at least one of the foregoing), to water or polyhydric organic components (such as ethylene glycol, propylene glycol, trimethylene glycol, 1,2- butylene glycol, 1,3-butanediol, 1,4-butanediol, 1,5-pentanediol, 1,2-hexylene glycol, 1,10-decanediol, 1,2-cyclohexanediol, 2-butene-l,4-diol, 3-cyclohexene-l,l- dimethanol, 4-methyl-3-cyclohexene-l,l-dimethanol, 3-methylene-l,5-pentanediol, diethylene glycol, (2-hydroxyethoxy)-l-propanol, 4-(2-hydroxyethoxy)-l-butanol, 5- (2-hydroxypropoxy)- 1 -pentanol, 1 -(2-hydroxymethoxy)-2-hexanol, 1 ~(2- hydroxypropoxy)-2-octanol, 3-allyloxy-l,5-pentanediol, 2-allyloxymethyl-2-methyl- 1,3 -propanediol, [4,4 - pentyloxy)-methyl]-l,3-propanediol, 3-(o-propenylphenoxy)- 1,2-propanediol, 2,2'-diisopropylidenebis(p-phenyleneoxy)diethanol, glycerol, 1,2,6- hexanetriol, 1,1,1-trimethylolethane, 1,1,1-trimethylolpropane, 3-(2-hydroxyethoxy)- 1,2-propanediol, 3-(2-hydroxypropoxy)-l,2-propanediol, 2,4-dimethyl-2-(2- hydroxyethoxy)-methylpentanediol- 1,5; 1,1,1 -tris [2-hydroxyethoxy) methyl] -ethane, l,l,l-tris[2-hydroxypropoxy)-methyl] propane, diethylene glycol, dipropylene glycol, pentaerythritol, sorbitol, sucrose, lactose, alpha-methylglucoside, alpha- hydroxyalkylglucoside, novolac resins, phosphoric acid, benzenephosphoric acid, polyphosphoric acids such as tripolyphosphoric acid and tetrapolyphosphoric acid, ternary condensation products, and so forth, as well as combinations comprising at least one of the foregoing). The alkylene oxides employed in producing polyoxyalkylene polyols normally have 2 to 4 carbon atoms. Propylene oxide and mixtures of propylene oxide with ethylene oxide are preferred. The polyols listed above can be used per se as the active hydrogen component.

[0027] A useful class of polyether polyols is represented generally by the following formula: R[(OCH_nH_2n)_zOH]_a wherein R is hydrogen or a polyvalent hydrocarbon radical; "a" is an integer equal to the valence of R, "n" in each occurrence is an integer of 2 to 4 inclusive (specifically 3), and "z" in each occurrence is an integer having a value of 2 to 200, or, more specifically, 15 to 100. Desirably, the polyether polyol comprises a mixture of one or more of dipropylene glycol, 1,4- butanediol, and 2-methyl-l,3-propanediol, and so forth.

[0028] Another type of active hydrogen-containing materials that can be used is polymer polyol compositions obtained by polymerizing ethylenically unsaturated monomers in a polyol as described in U.S. Pat No. 3,383,351. Exemplary monomers for producing such compositions include acrylonitrile, vinyl chloride, styrene, butadiene, vinylidene chloride, and other ethylenically unsaturated monomers. The polymer polyol compositions can contain 1 weight percent (wt%) to 70 wt%, or, more specifically, 5 wt% to 50 wt%, and even more specifically, 10 wt% to 40 wt% monomer polymerized in the polyol, where the weight percent is based on the total weight of polyol. Such compositions are conveniently prepared by polymerizing the monomers in the selected polyol at a temperature of 40⁰C to 150⁰C in the presence of a free radical polymerization catalyst such as peroxides, persulfates, percarbonate, perborates, azo compounds, and combinations comprising at least one of the foregoing.

[0029] The active hydrogen-containing component can also contain polyhydroxyl-containing compounds, such as hydroxyl-terminated polyhydrocarbons (U.S. Patent No. 2,877,212); hydroxyl-terminated polyformals (U.S. Patent No. 2,870,097); fatty acid triglycerides (U.S. Patent Nos. 2,833,730 and 2,878,601); hydroxyl-terminated polyesters (U.S. Patent Nos. 2,698,838, 2,921,915, 2,591,884, 2,866,762, 2,850,476, 2,602,783, 2,729,618, 2,779,689, 2,811,493, 2,621,166 and 3,169,945); hydroxymethyl-terminated perfluoromethylenes (U.S. Patent Nos. 2,911,390 and 2,902,473); hydroxyl-terminated polyalkylene ether glycols (U.S. Patent No. 2,808,391; British Pat. No. 733,624); hydroxyl-terminated polyalkylenearylene ether glycols (U.S. Patent No. 2,808,391); and hydroxyl- terminated polyalkylene ether triols (U.S. Patent No. 2,866,774).

[0030] hi one embodiment, the reactive composition for producing a foam can be substantially in accordance with Japanese Patent Publication No. Sho 53-8735. The polyol desirably used has a repeated unit (referred to as "Unit") of each of PO (propylene oxide) and/or PTMG (tetrahydrofuran subjected to ring-opening polymerization), or the like, hi a specific embodiment, the amount of EO (ethylene oxide; (CH₂CH₂O)_n) is minimized in order to improve the hygroscopic properties of the foam. Specifically, the percentage of an EO Unit (or an EO Unit ratio) in a polyol can be less than or equal to about 20%. For example, when a polyol to be used merely consists of a PO-Unit and an EO Unit, this polyol is set to be within the range of [the PO Unit]: [the EO Unit] = 100:0 to about 80:20. The percentage of an EO Unit is referred to as "EO content".

[0031] The polyols can have hydroxyl numbers that vary over a wide range. In general, the hydroxyl numbers of the polyols, including other cross-linking additives, if used, can be about 28 to about 1,000, and higher, or, more specifically, about 100 to about 800. The hydroxyl number is defined as the number of milligrams of potassium hydroxide required for the complete neutralization of the hydrolysis product of the fully acetylated derivative prepared from 1 gram of polyol or mixtures of polyols with or without other cross-linking additives. The hydroxyl number can also be defined by the equation:

OH = 56.1 x 1000 x f

M_w wherein: OH is the hydroxyl number of the polyol, f is the average functionality, that is the average number of hydroxyl groups per molecule of polyol, and Mw is the average molecular weight of the polyol. [0032] As noted above, the foams can be chemically blown and/or physically blown (e.g., mechanically frothed). When used, a wide variety of blowing agent(s) can be employed in the reactive compositions, including chemical and/or physical blowing agents. Chemical blowing agents include, for example, water, and chemical compounds that decompose with a high gas yield under specified conditions, for example within a narrow temperature range. Desirably, the decomposition products do not effloresce or have a discoloring effect on the foam product. Exemplary chemical blowing agents include water, azoisobutyronitrile, azodicarbonamide (i.e. azo-bis-formamide) and barium azodicarboxylate; substituted hydrazines (e.g., diphenylsulfone-3,3'-disulfohydrazide, 4,4'-hydroxy-bis-(benzenesulfohydrazide), trihydrazinotriazine, and aryl-bis-(sulfohydrazide)); semicarbazides (e.g., p-tolylene sulfonyl semicarbazide an d4,4'-hydroxy-bis-(benzenesulfonyl semicarbazide)); triazoles (e.g., 5-morpholyl-l,2,3,4- thiatriazole); N-nitroso compounds (e.g., N,N'- dinitrosopentamethylene tetramine and N,N-dimethyl-N,N^T- dinitrosophthalmide); benzoxazines (e.g., isatoic anhydride); as well as combinations comprising at least one of the foregoing, such as, sodium carbonate/citric acid mixtures.

[0033] The amount of blowing agents will vary depending on the agent and the desired foam density, hi general, these blowing agents are used in an amount of about 0.1 wt% to about 10 wt%, based upon a total weight of the reactive composition. When water is employed as at least one of the blowing agent(s) (e.g., in an amount of about 0.1 wt% to about 8 wt% based upon the total weight of reactive composition), it is generally desirable to control the curing reaction by selectively employing catalysts.

[0034] Physical blowing agents can also (or alternatively) be used. These blowing agents can be selected from a broad range of materials, including hydrocarbons, ethers, esters, (including partially halogenated hydrocarbons, ethers, and esters), and so forth, as well as combinations comprising at least one of the foregoing. Exemplary physical blowing agents include the CFCs

(chlorofluorocarbons) such as 1,1-dichloro-l-fluoroethane, l,l-dichloro-2,2,2- trifluoro-ethane, monochlorodifluoromethane, and l-chloro-l,l-difluoroethane; the FCs (fluorocarbons) such as 1,1,1,3,3,3-hexafluoropropane, 2,2,4,4- tetrafluorobutane, l,l,l,3,3,3-hexafluoro-2-methylpropane, 1,1,1,3,3- pentafluoropropane, 1,1,1 ,2,2-pentafluoropropane, 1,1,1 ,2,3-pentafluoropropane, 1,1,2,3,3-pentafluoropropane, 1,1,2,2,3-pentafluoropropane, 1,1,1,3,3,4- hexafluorobutane, 1,1,1 ,3 ,3 -pentafluorobutane, 1,1,1 ,4,4,4-hexafluorobutane, 1,1,1,4,4-pentafluorobutane, 1,1, 2,2,3, 3-hexafluoropropane, 1,1,1,2,3,3- hexafluoropropane, 1,1-difluoroethane, 1,1,1,2-tetrafluoroethane, and pentafluoroethane; the FE' s (fluoroethers) such as methyl- 1,1,1-trifluoroethylether and difluoromethyl- 1,1,1-trifluoroethylether; hydrocarbons such as n-pentane, isopentane, and cyclopentane; and well as combinations comprising at least one of the foregoing. As with the chemical blowing agents, the physical blowing agents are used in an amount sufficient to give the resultant foam the desired bulk density. The physical blowing agents can be used in an amount of about 5 wt% to about 50 wt% of the reactive composition, or, more specifically, about 10 wt% to about 30 wt%.

[0035] A number of the catalysts capable of catalyzing the reaction of the isocyanate component with the active hydrogen-containing component can be used in the foam preparation. Exemplary catalysts include phosphines; tertiary organic amines; organic and inorganic acid salts of, and organometallic derivatives of: bismuth, lead, tin, iron, antimony, uranium, cadmium, cobalt, thorium, aluminum, mercury, zinc, nickel, cerium, molybdenum, vanadium, copper, manganese, and zirconium; as well as combinations comprising at least one of the foregoing. Specific examples of such catalysts include dibutyltin dilaurate, dibutyltin diacetate, stannous octoate, lead octoate, cobalt naphthenate, triethylamine, triethylenediamine, N,N,N',N'-tetramethylethylenediamine, 1,1,3,3-tetramethylguanidine, N₅N₅N¹N'- tetramethyl-l,3-butanediamine, N,N-dimethylethanolamine, N₅N- diethylethanolamine, 1,3,5-tris (N,N-dimethylaminopropyl)-s-hexahydrotriazine, o- and p-(dimethylaminomethyl) phenols, 2,4,6-tris(dimethylaminomethyl) phenol, N₅N- dimethylcyclohexylamine, pentamethyldiethylenetriamine, 1,4-diazobicyclo [2.2.2] octane, N-hydroxyl-alkyl quaternary ammonium carboxylates and tetramethylammonium formate, tetramethylammonium acetate, tetramethylammonium 2-ethylhexanoate, and so forth, as well as combinations comprising at least one of the foregoing catalysts. Additional catalysts are set forth in commonly assigned U.S. Patent Application Serial No. 11/200,536, filed August 9, 2005. [0036] Metal acetyl acetonates based on metals such as aluminum, barium, cadmium, calcium, cerium (III), chromium (III), cobalt (II), cobalt (III), copper (II), indium, iron (II), lanthanum, lead (II), manganese (II), manganese (III), neodymium, nickel (II), palladium (II), potassium, samarium, sodium, terbium, titanium, vanadium, yttrium, zinc and zirconium. A common catalyst is bis(2,4- pentanedionate) nickel (II) (also known as nickel acetylacetonate or diacetylacetonate nickel) and derivatives thereof such as diacetonitrilediacetylacetonato nickel, diphenylnitrilediacetylacetonato nickel, bis(triphenylphosphine)diacetyl acetylacetonato nickel, and so forth, can be employed. Ferric acetylacetonate (FeAA) is particularly preferred, due to its relative stability, good catalytic activity, and lack of toxicity.

[0037] Added to the metal acetyl acetonate can be acetyl acetone (2,4- pentanedione), as disclosed in commonly assigned U.S. Patent No. 5,733,945 to Simpson. Not to be limited by theory, the acetyl acetone provides heat latency, which allows time for the required mixing, casting and other procedures, and avoids deleterious premature curing during low temperature processing. However, as the material is cured in several heating zones and the temperature of the urethane mixture rises, the acetyl acetone is driven off. With the acetyl acetone removed together with its associated delaying function, the metal acetyl acetonate is allowed to resume its normally high reactivity and provide a very high level of catalysis at the end of the polyurethane reaction. This high reactivity late in the processing cycle is advantageous and provides improved physical properties such as compression set. In general, the ratio of metal acetyl acetonate to acetyl acetone is about 2:1 on a weight basis.

[0038] The amount of catalyst present in the reactive composition can be about 0.03 wt% to about 3.0 wt%, based on the weight of the active hydrogen- containing component.

[0039] In one embodiment, when water is used as the blowing agent, ferric acetylacetonate (FeAA) is selected as the catalyst. Other catalysts or adjuvants, e.g., amines, can be used to adjust the relative reaction rates of water and urethane. The water reacts with the isocyanate releasing CO₂. The FeAA with acetyl acetone simultaneously catalyzes the curing reaction in a delayed fashion, which prevents premature curing and therefore allows the chemical (and optionally physical) blowing to continue unhindered. The catalyst eventually permits a full cure of the polyurethane foam. The metal acetylacetonate is most conveniently added by predissolution in a solvent. Exemplary solvent such as dipropylene glycol or other hydroxyl containing components which will then participate in the reaction and become part of the final product.

[0040] A wide variety of surfactants can be used for purposes of stabilizing the polyurethane foam before it is cured, including mixtures of surfactants. Organosilicone surfactants are especially useful, such as a copolymer consisting essentially of SiO₂ (silicate) units and (CH3)₃SiOo_.s (trimethylsiloxy) units in a molar ratio of silicate to trimethylsiloxy units of about 0.8:1 to about 2.2:1, or, more specifically, about 1:1 to about 2.0:1. Another organosilicone surfactant stabilizer is a partially cross-linked siloxane-polyoxyalkylene block copolymer and mixtures thereof wherein the siloxane blocks and polyoxyalkylene blocks are linked by silicon to carbon, or by silicon to oxygen to carbon, linkages. The siloxane blocks comprise hydrocarbon-siloxane groups and have an average of at least two valences of silicon per block combined in the linkages. At least a portion of the polyoxyalkylene blocks comprise oxyalkylene groups and are polyvalent, i.e., have at least two valences of carbon and/or carbon-bonded oxygen per block combined in said linkages. Any remaining polyoxyalkylene blocks comprise oxyalkylene groups and are monovalent, i.e., have only one valence of carbon or carbon-bonded oxygen per block combined in said linkages. Additional organopolysiloxane-polyoxyalkylene block copolymers include those described in U.S. Patent Nos. 2,834,748, 2,846,458, 2,868,824, 2,917,480 and 3,057,901. Combinations comprising at least one of the foregoing surfactants can also be employed. The amount of the organosilicone polymer used as a foam stabilizer can vary over wide limits, e.g., about 0.5 wt% to about 10 wt% or more, based on the amount of the active hydrogen component, or, more specifically, about 1.0 wt% to about 6.0 wt%.

[0041] Other, optional additives can be added to the reactive composition, e.g., the polyurethane froth mixture, in the manufacturing process. For example, additives such as fillers (alumina trihydrate, silica, talc, calcium carbonate, clay, and so forth), dyes, pigments (for example titanium dioxide and iron oxide), antioxidants, antiozonants, flame retardants, UV stabilizers, conductive fillers, conductive polymers, and so forth, as well as combinations comprising at least one of the foregoing additives, can also be used.

[0042] In one embodiment, the foams can be produced by mechanically mixing the reactive composition (i.e., isocyanate component(s), active hydrogen- containing component(s), froth-stabilizing surfactant(s), catalyst(s), and any optional additive(s)) with a froth- forming gas in a predetermined amount. In one manner of proceeding, the components of the reactive composition are first mixed together and then subjected to mechanical frothing with air. Alternatively, the components can be added sequentially to the liquid phase during the mechanical frothing process. The gas phase of the froths can be air because of its cheapness and ready availability. However, if desired, other gases can be used that are gaseous at ambient conditions and that are substantially inert or non-reactive with all components of the liquid phase. Other gases include, for example, nitrogen, carbon dioxide, and fluorocarbons that are normally gaseous at ambient temperatures.

[0043] The inert gas is incorporated into the liquid phase by mechanical beating of the liquid phase in high shear equipment such as in a Hobart mixer or an Oakes mixer. The gas can be introduced under pressure or it can be drawn in from the overlying atmosphere by the beating or whipping action as in a Hobart mixer. The mechanical beating operation can be conducted at standard pressures, for example pressures of about 100 pounds per square inch (psi) to about 200 psi (689 kilopascals (kPa) to 1,379 kPa). Readily available mixing equipment can be used. The amount of inert gas beaten into the liquid phase is controlled by gas flow metering equipment to produce a froth of the desired density. The mechanical beating is conducted over an appropriate period to obtain the desired froth density, for example a few seconds in an Oakes mixer, or 3 to 30 minutes in a Hobart mixer. The froth as it emerges from the mechanical beating operation is substantially chemically stable and is structurally stable, but easily workable at ambient temperatures, e.g., about 10⁰C to about 40⁰C.

[0044] After frothing, the reactive mixture is deposited onto the first carrier. For convenience, this first carrier can be referred to as "bottom carrier," and is generally a moving support that may or may not readily release the cured foam. A second carrier, also referred to herein as a "surface protective layer" or "top carrier" can optionally be placed on top of the froth. The optional top carrier is also a moving support that also may or may not readily release from the cured foam, provided that at least one carrier readily releases from the foam. The top carrier can be applied almost simultaneously with the froth. Before applying the top carrier, the foam can be spread to a layer of desired thickness, e.g., by a doctoring blade or other spreading device. Alternatively, placement of the top carrier can be used to spread the foam and adjust the frothed layer to the desired thickness. In still another embodiment, a coater can be used after placement of the top carrier to adjust the height of the foam. Once at the desired height, the frothed foam can also be blown under the influence of a physical or chemical blowing agent.

[0045] hi practice, the carriers can be played out from supply rolls and ultimately rewound on take-up rolls upon separation from the cured polyurefhane foam. The selection of materials for the top and bottom carriers will depend on factors such as the desired degree of support and flexibility, the desired degree of releasability from the cured foam, cost, aesthetics, and so forth, considerations. Paper, thin sheets of metal such as stainless steel, or polymer films such as polyethylene terephthalate, silicone, or the like, can be used. The material can be coated with a release coating. In one embodiment, the carrier can be coated with a material intended to be transferred to the surface of the cured polyurethane foam, for example a substrate film that is releasable from the carrier. A fibrous web or other filler material can be disposed on the surface of the carrier, and thereby become ultimately incorporated into the cured foam, hi another embodiment, the foam can cure to one or both of the carriers. Thus, one carrier can form part of the final product instead of being separated from the foam. Alternatively, or in addition, a conveyor belt can be used as the bottom carrier. The carriers can have a plain surface or a textured surface. In a particular embodiment, the surface of the foam is provided with a skin layer.

[0046] hi another example, silicone foams are produced as a result of the reaction between water and hydride groups in a polysiloxane polymer precursor composition with the consequent liberation of hydrogen gas. This reaction is generally catalyzed by a noble metal, specifically a platinum catalyst, hi one embodiment, the polysiloxane polymer has a viscosity of about 100 to 1,000,000 poise at 25⁰C and has chain substituents selected from the group consisting of hydride, methyl, ethyl, propyl, vinyl, phenyl, and trifluoropropyl. The end groups on the polysiloxane polymer can be hydride, hydroxyl, vinyl, vinyl diorganosiloxy, alkoxy, acyloxy, allyl, oxime, aminoxy, isopropenoxy, epoxy, mercapto groups, or other known, reactive end groups. Suitable silicone foams can also be produced by using several polysiloxane polymers, each having different molecular weights (e.g., bimodal or trimodal molecular weight distributions) as long as the viscosity of the combination lies within the above specified values. It is also possible to have several polysiloxane base polymers with different functional or reactive groups in order to produce the desired foam. In one embodiment, the polysiloxane polymer comprises about 0.2 moles of hydride (Si-H) groups per mole of water.

[0047] Depending upon the chemistry of the polysiloxane polymers used, a catalyst, generally platinum or a platinum-containing catalyst, can be used to catalyze the blowing and the curing reaction. The catalyst can be deposited onto an inert carrier, such as silica gel, alumina, or carbon black. In one embodiment, an unsupported catalyst selected from among chloroplatinic acid, its hexahydrate form, its alkali metal salts, and its complexes with organic derivatives is used. Exemplary catalysts are the reaction products of chloroplatinic acid with vinylpolysiloxanes such as 1,3-divinyltetrarnethyldisiloxane, which are treated or otherwise with an alkaline agent to partly or completely remove the chlorine atoms; the reaction products of chloroplatinic acid with alcohols, ethers, and aldehydes; and platinum chelates and platinous chloride complexes with phosphines, phosphine oxides, and with olefins such as ethylene, propylene, and styrene. It can also be desirable, depending upon the chemistry of the polysiloxane polymers to use other catalysts such as dibutyl tin dilaurate in lieu of platinum based catalysts.

[0048] Various platinum catalyst inhibitors can also be used to control the kinetics of the blowing and curing reactions in order to control the porosity and density of the silicone foams. Examples of such inhibitors include polymethylvinylsiloxane cyclic compounds and acetylenic alcohols. These inhibitors should not interfere with the foaming and curing in such a manner that destroys the foam. [0049] Physical or chemical blowing agents can be used to produce the silicone foam, including the physical and chemical blowing agents listed above for polyurethanes. Other examples of chemical blowing agents include benzyl alcohol, methanol, ethanol, isopropyl alcohol, butanediol, and silanols. hi one embodiment, a combination of methods of blowing is used to obtain foams having desirable characteristics. For example, a physical blowing agent such as a chlorofluorocarbon can be added as a secondary blowing agent to a reactive mixture wherein the primary mode of blowing is the hydrogen released as the result of the reaction between water and hydride substituents on the polysiloxane.

[0050] hi the production of silicone foams, the reactive components of the precursor composition are stored in two packages, one containing the platinum catalyst and the other the polysiloxane polymer containing hydride groups, which prevents premature reaction. In another method of production, the polysiloxane polymer is introduced into an extruder along with water, physical blowing agents if necessary, and other desirable additives. The platinum catalyst is then metered into the extruder to start the foaming and curing reaction. The use of physical blowing agents such as liquid carbon dioxide or supercritical carbon dioxide in conjunction with chemical blowing agents such as water can give rise to foam having much lower densities, hi yet another method, the liquid silicone components are metered, mixed and dispensed into a device such a mold or a continuous coating line. The foaming then occurs either in the mold or on the continuous coating line.

[0051] Alternatively, a soft, silicone composition can be formed by the reaction of a precursor composition comprising a liquid silicone composition comprising a polysiloxane having at least two alkenyl groups per molecule; a polysiloxane having at least two silicon-bonded hydrogen atoms in a quantity effective to cure the composition; a catalyst; and optionally a reactive or non-reactive polysiloxane fluid having a viscosity of about 100 to about 1000 centipoise. Suitable reactive silicone compositions are low durometer, 1 : 1 liquid silicone rubber (LSR) or liquid injection molded (LIM) compositions. Because of their low inherent viscosity, the use of the low durometer LSR or LEVI facilitates the addition of higher filler quantities, and results in formation of a soft foam. [0052] The reactive or non-reactive polysiloxane fluid allows higher quantities of filler to be incorporated into the cured silicone composition, thus lowering the obtained volume and surface resistivity values. In one embodiment, the polysiloxane fluid remains within the cured silicone and is not extracted or removed. The reactive silicone fluid thus becomes part of the polymer matrix, leading to low outgassing and little or no migration to the surface during use. Pn one embodiment, the boiling point of the non-reactive silicone fluid is high enough such that when it is dispersed in the polymer matrix, it does not evaporate during or after cure, and does not migrate to the surface or outgas.

[0053] Pn one embodiment, LSR or LIM systems are provided as two-part formulations suitable for mixing in ratios of about 1 : 1 by volume. The "A" part of the formulation comprises one or more polysiloxanes having two or more alkenyl groups and has an extrusion rate of less than about 500 g/minute. Suitable alkenyl groups are exemplified by vinyl, allyl, butenyl, pentenyl, hexenyl, and heptenyl, with vinyl being particularly suitable. The alkenyl group can be bonded at the molecular chain terminals, in pendant positions on the molecular chain, or both. Other silicon-bonded organic groups in the polysiloxane having two or more alkenyl groups are exemplified by substituted and unsubstituted monovalent hydrocarbon groups, for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl. Exemplary substituents are methyl and phenyl groups.

[0054] The alkenyl-containing polysiloxane can have straight chain, partially branched straight chain, branched-chain, or network molecule structure, or can be a mixture of two or more selections from polysiloxanes with the exemplified molecular structures. The alkenyl-containing polysiloxane is exemplified by trimethylsiloxy- endblocked dimethylsiloxane-methylvinylsiloxane copolymers, trimethylsiloxy- endblocked methylvinylsiloxane-methylphenylsiloxane copolymers, trimethylsiloxy- end blocked dimethylsiloxane-methylvinylsiloxane-methylphenylsiloxane copolymers, dimethylvinylsiloxy-endblocked dimethylpolysiloxanes, dimethylvinylsiloxy-endblocked methylvinylpolysiloxanes, dimethylvinylsiloxy- endblocked methylvinylphenylsiloxanes, dimethylvinylsiloxy-endblocked dimethylvinylsiloxane-methylvinylsiloxane copolymers, dimethylvinylsiloxy- endblocked dimethylsiloxane-methylphenylsiloxane copolymers, dimethylvinylsiloxy-endblocked dimethylsiloxane-diphenylsiloxane copolymers, polysiloxane comprising R₃SiOy₂ and SiO_4/2 units, polysiloxane comprising RSiO_3/2 units, polysiloxane comprising the R₂Si0_2/2 and RSiO_3/2 units, polysiloxane comprising the R₂Si0₂/₂, RSiO₃/₂ and SiO_4/2 units, and a mixture of two or more of the preceding polysiloxanes. R represents substituted and unsubstituted monovalent hydrocarbon groups, for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3- trifluoropropyl, with the proviso that at least 2 of the R groups per molecule are alkenyl.

[0055] The "B" component of the LSR or LIM system comprises one or more polysiloxanes that contain at least two silicon-bonded hydrogen atoms per molecule and has an extrusion rate of less than about 500 g/minute. The hydrogen can be bonded at the molecular chain terminals, in pendant positions on the molecular chain, or both. Other silicon-bonded groups are organic groups exemplified by non-alkenyl, substituted and unsubstituted monovalent hydrocarbon groups, for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3 -trifluoropropyl. Exemplary substituents are methyl and phenyl groups.

[0056] The hydrogen-containing polysiloxane component can have straight- chain, partially branched straight-chain, branched-chain, cyclic, network molecular structure, or can be a mixture of two or more selections from polysiloxanes with the exemplified molecular structures. The hydrogen-containing polysiloxane is exemplified by trimethylsiloxy-endblocked methylhydrogenpolysiloxanes, trimethylsiloxy-endb locked dimethylsiloxane-methylhydrogensiloxane copolymers, trimethylsiloxy-endblocked methylhydrogensiloxane-methylphenylsiloxane copolymers, trimethylsiloxy-endblocked dimethylsiloxane-methylhydrogensiloxane- methylphenylsiloxane copolymers, dimethylhydrogensiloxy-endblocked dimethylpolysiloxanes, dimethylhydrogensiloxy-endblocked methylhydrogenpolysiloxanes, dimethylhydrogensiloxy-endblocked dimethylsiloxanes-methylhydrogensiloxane copolymers, dimethylhydrogensiloxy- endblocked dimethylsiloxane-methylphenylsiloxane copolymers, and dimethylhydrogensiloxy-endb locked methylphenylpolysiloxanes.

[0057] The hydrogen-containing polysiloxane component is added in an amount sufficient to cure the composition, specifically in a quantity of about 0.5 to about 10 silicon-bonded hydrogen atoms per alkenyl group in the alkenyl-containing polysiloxane.

[0058] The silicone composition further comprises, generally as part of Component "A," a catalyst such as platinum to accelerate the cure. Platinum and platinum compounds known as hydrosilylation-reaction catalysts can be used, for example platinum black, platinum-on-alumina powder, platinum-on-silica powder, platinum-on-carbon powder, chloroplatinic acid, alcohol solutions of chloroplatinic acid platinum-olefin complexes, platinum-alkenylsiloxane complexes and the catalysts afforded by the microparticulation of the dispersion of a platinum addition- reaction catalyst, as described above, in a thermoplastic resin such as methyl methacrylate, polycarbonate, polystyrene, silicone, and the like. Mixtures of catalysts can also be used. A quantity of catalyst effective to cure the present composition is generally from 0.1 to 1,000 parts per million (by weight) of platinum metal based on the combined amounts of alkenyl and hydrogen components.

[0059] The composition optionally further comprises one or more polysiloxane fluids having a viscosity of less than or equal to about 1000 centipoise, specifically less than or equal to about 750 centipoise, more specifically less than or equal to about 600 centipoise, and most specifically less than or equal to about 500 centipoise. The polysiloxane fluids can also have a viscosity of greater than or equal to about 100 centipoises. The polysiloxane fluid component is added for the purpose of decreasing the viscosity of the composition, thereby allowing at least one of increased filler loading, enhanced filler wetting, and enhanced filler distribution, and resulting in cured compositions having lower resistance and resistivity values. Use of the polysiloxane fluid component can also reduce the dependence of the resistance value on temperature, and/or reduce the timewise variations in the resistance and resistivity values. Use of the polysiloxane fluid component obviates the need for an extra step during processing to remove the fluid, as well as possible outgassing and migration of diluent during use. The polysiloxane fluid should not inhibit the curing reaction, that is, the addition reaction, of the composition, but it may or may not participate in the curing reaction.

[0060] The non-reactive polysiloxane fluid has a boiling point of greater than about 500°F (260⁰C), and can be branched or straight-chained. The non-reactive polysiloxane fluid comprises silicon-bonded non-alkenyl organic groups exemplified by substituted and unsubstituted monovalent hydrocarbon groups, for example, alkyl groups such as methyl, ethyl, propyl, butyl, pentyl, and hexyl; aryl groups such as phenyl, tolyl, and xylyl; aralkyl groups such as benzyl and phenethyl; and halogenated alkyl groups such as 3-chloropropyl and 3,3,3-trifluoropropyl. Exemplary substituents are methyl and phenyl groups. Thus, the non-reactive polysiloxane fluid can comprise R₃SiOy₂ and SiO₄/₂ units, RSiO_3/2 units, R₂Si0_2/2 and RSiO_3/2 units, or R₂Si0₂/₂, RSiO₃/₂ and SiO_4/2 units, wherein R represents substituted and unsubstituted monovalent hydrocarbon groups selected from the group consisting of alkyl, methyl, ethyl, propyl, butyl, pentyl, hexyl, aryl, phenyl, tolyl, xylyl, aralkyl, benzyl, phenethyl, halogenated alkyl, 3-chloropropyl, and 3,3,3-trifluoropropyl. Because the non-reactive polysiloxane is a fluid and has a significantly higher boiling point (greater than about 230⁰C (500⁰F)), it allows the incorporation of higher quantities of filler, but does not migrate or outgas. Examples of non-reactive polysiloxane fluids include DC 200 from Dow Corning Corporation.

[0061] Reactive polysiloxane fluids co-cure with the alkenyl-containing polysiloxane and the polysiloxane having at least two silicon-bonded hydrogen atoms, and therefore can themselves contain alkenyl groups or silicon-bonded hydrogen groups. Such compounds can have the same structures as described above in connection with the alkenyl-containing polysiloxane and the polysiloxane having at least two silicon-bonded hydrogen atoms, but in addition have a viscosity of less than or equal to about 1000 centipoise (cps), specifically less than or equal to about 750 cps, more specifically less than or equal to about 600 cps, and most specifically less than or equal to about 500 cps. In one embodiment, the reactive polysiloxane fluids have a boiling point greater than the curing temperature of the addition cure reaction. [0062] The silicone foams can further optionally comprise a curable silicone gel formulation. Silicone gels are lightly cross-linked fluids or under-cured elastomers. They are unique in that they range from very soft and tacky to moderately soft and only slightly sticky to the touch. Use of a gel formulation decreases the viscosity of the composition, thereby allowing at least one of an increased filler loading, enhanced filler wetting, and/or enhanced filler distribution, thereby resulting in cured compositions having lower resistance and resistivity values and increased softness. Suitable gel formulations can be either two-part curable formulations or one-part formulations. The components of the two-part curable gel formulations is similar to that described above for LSR systems (i.e., an organopolysiloxane having at least two alkenyl groups per molecule and an organopolysiloxane having at least two silicon-bonded hydrogen atoms per molecule). The main difference lies in the fact that no filler is present, and that the molar ratio of the silicon-bonded hydrogen groups (Si-H) groups to the alkenyl groups is usually less than one, and can be varied to create a "under-cross linked" polymer with the looseness and softness of a cured gel. Specifically, the ratio of silicone-bonded hydrogen atoms to alkenyl groups is less than or equal to about 1.0, specifically less than or equal to about 0.75, more specifically less than or equal to about 0.6, and most specifically less than or equal to about 0.1. An example of a suitable two-part silicone gel formulation is SYLGARD® 527 gel commercially available from the Dow Corning Corporation.

[0063] The silicone foams can be cast and processed using only a bottom carrier, or both a bottom carrier and a top carrier as described above.

[0064] In a specific embodiment, in order to enhance the structural integrity of an article, e.g., to improve the handling properties of the product, a substrate film can be cured to a foamed sheet (e.g., bound to the sheet). This substrate film can also serve as a transfer means for the frothed reactive composition in a production apparatus. Therefore, the substrate firm can comprise any resin having low heat- shrinkable properties, a physical strength resistant to a tensile force applied by a roller machine, and resistance properties to heat applied by a heater (e.g., furnace, oven, and so forth). For example, a resin such as polyolefin, polyester, polyamide, polyvinyl chloride can be used, although it is desirable to use polyethylene terephthalate (PET) in terms of cost in particular. Depending upon the quality of material, the thickness of a substrate film can be about 10 micrometers (μ.m) to 500 micrometer, and more specifically, about 25 μm to about 125 μm.

[0065] The assembly of the carrier(s) and foam layer (after optional blowing) can be delivered to a heating zone for cure of the foams. The temperatures are maintained in a range suitable for curing the foam, for example at about 90⁰C to about 22O⁰C, depending on the composition of the foam material. Differential temperatures can be established for purposes of forming an integral skin on an outside surface of the foam or for adding a relatively heavy layer to the foam.

[0066] After the foam is heated and cured or partially melted, it can be passed to a cooling zone where it is cooled by any suitable cooling device such as fans. Where appropriate, the carriers are removed and the foam can be taken up on a roll. Alternatively, the foam can be subjected to further processing, for example lamination (bonding using heat and pressure) to one or both of the carrier layers, and so forth. The processed sheet can be rewound for collection on the product-collecting roll, hi such a production mode, the length of the foamed sheet can be up to 5 meters or more. An apparatus for the manufacture of a polyurethane foam sheet are described in U.S. Patent Application Serial No. 11/200,536.

[0067] The holes can be formed into the material at various points during the sheet forming process (e.g., if the material comprises a thermoplastic, before, during, and/or after partial curing of the sheet; and if the material comprises a thermoset, before, during and/or after partial setting (e.g., solidification) of the sheet), hi some embodiments, the holes are formed after the sheet is cast, but before substantial cure of the foam. In another embodiment, the foam is at least partially cured prior to hole formation to inhibit the foam from flowing into and closing the holes, hi another embodiment, the holes are formed during the curing process. In this embodiment, the hole formed can be maintained through at least a portion of the curing to attain the desired hole shape, depth, and/or size. For example, the hole can be formed when the extent of reaction of the material (e.g., the degree of cure; or, in the case of thermoplastic material(s),the degree of solidification), is less than or equal to about 90%, or, more specifically, is less than or equal to about 80%, or, yet more specifically, is less than or equal to about 60%. [0068] The holes can be formed into the sheet using various techniques, such as fluid jets, which as used herein includes liquid (e.g., water) and gas jets (e.g., inert gas(es) such as air, nitrogen, carbon dioxide, fluorocarbon(s), and so forth, as well as combinations comprising at least one of these gases). Depending upon the desired effect of each jet, various nozzles can be employed to attain the desired control, pressure, hole geometry, and so forth. For example, a pattern of jets can be used in a single shot or multiple shot system, hi one embodiment, the pattern of jets can be in a fixed location, with the foam sheet composition continuously passing across the pattern of fluid jets. In one embodiment, a single pattern of jets can form openings through the sheet, while in other embodiments, a first jet pattern could displace the foam, while one or more subsequent jet pattern could form the opening through the sheet in some or all of the holes. Alternatively, the first jet pattern could apply multiple hits in the same location to the foam sheet to help improve the hole formation and structure. For example, the first jet pattern could impinge fluid on the sheet for a first duration and then impinge fluid a second time in the same sheet location for a second duration. In another embodiment, the first jet pattern can apply multiple hits in different locations to form holes of different sizes or to form patterns in the sheet with the holes, hi yet another embodiment, the first jet pattern can continuously impinge fluid onto the foam sheet. One example of this embodiment could be where the fluid jet pattern moves along with the sheet to form the holes and helps to prevent material flowback. Another example could be where the foam sheet is held still as the pattern of fluid jets impinges fluid on the sheet. In either example, the fluid can be continuously impinged on the foam sheet until the foam is partially, substantially, or fully cured. The continuous fluid impingement on the foam sheet can be useful for foam compositions having slow cure rates and/or low viscosities where material flowback into the formed holes can be a problem. In still another example, a plurality of rows or patterns of jets could be timed to impinge the same location of the foam sheet at multiple times while the as that location of the sheet continuously moves past the plurality of jet rows or patterns.

[0069] The fluid jet is directed at the sheet at a sufficient pressure to attain the desired hole depth and/or to form an opening through the sheet. The specific pressure is dependent upon the foam formulation, specific sheet composition, thickness, and degree of cure. Possible pressures are about 0 pounds per square inch (psi) to about 100 psi, or more specifically, about 1 psi to about 50 psi, or, even more specifically, about 5 psi to about 25 psi, and, yet more specifically, about 10 psi to about 15 psi. Likewise, the temperature of the fluid can be varied and is also dependent upon the foam formulation, specific sheet composition, thickness, and degree of cure. The fluid from the jets can also be heated so as to aid in curing of the foam sheet. The fluid, therefore, can be heated to a temperature range suitable for curing the foam. Possible temperatures can be about 50 ⁰C to about 300 ⁰C, specifically about 90 ⁰C to about 220 ⁰C. Alternatively, or in addition, the sheet could be located in operational communication with a mesh release carrier. Here, the mesh pattern could be designed into the release carrier such that the release carrier could create the design (solely or in combination with the fluid jets). Where a top and a bottom carrier are used to produce the foam, in one embodiment, one or both of the carriers can comprise openings in the desired hole pattern.

[0070] The properties of the foams formed as described above (e.g., density, modulus, compression load deflection, tensile strength, tear strength, and so forth) can be adjusted by varying the components of the reactive compositions, hi general, when used as a component of footwear, the foam can have a density of about 50 kg/m³ to about 500 kg/m³, specifically about 70 kg/m³ to about 400 kg/m³, more specifically about 100 kg/m³ to about 350 kg/m³, still more specifically about 200 kg/m³ to about 300 kg/m³. Such foams can also have a thickness of about 0.3 millimeters (mm) to about 13 mm, specifically about 0.3 mm to about 9 mm, more specifically about 0.3 mm to about 5 mm, and even more specifically, about 0.3 mm to about 3 mm.

[0071] The physical properties of such foams are excellent. For example, such foams can have a compression set resistance of less than or equal to about 10%, or, more specifically, less than or equal to about 5%.

[0072] In order to provide good mechanical properties to the foam, the average cellular diameter of the foam can be about 10 micrometers (μm) to about 1 millimeter (mm), or, more specifically, about 50 micrometers to about 500 micrometers. In open-celled foams where at least a portion of the cells extend through the sheet, through holes can be distinguished from such open cells on the basis of size. For example, in a mechanically frothed foam, the smallest diameter of a through hole is at least ten times larger than the largest diameter of a cell. In a blown foam, or non-microcellular foam, the smallest diameter of a through hole is at least twice as large as the largest diameter of the cell.

[0073] Due to the unique process of forming holes in the sheet, there is little or no waste produced as a result of forming the holes. Another significant advantage of using a fluid jet to form a hole in a foam sheet is that the number, arrangement, size, and conformation of the hole(s) can be readily adjusted by adjusting the location, pattern, or firing sequence of the jet(s), the force used, and like parameters. Such adjustments do not require expensive retooling of molds. For example, as illustrated by sheet 10 in Figure 1, a regular pattern of holes 12 of the same size can be formed completely through the sheet 10. hi another embodiment, as shown in Figure 2, holes 22 of irregular size can be formed into or through sheet 20 in an irregular pattern. Combinations of hole sizes, depths, and shapes can be produced to attain, for example, a design, as is illustrated in Figure 3 by holes 32 in sheet 30. Examples of designs can include, without limitation, letters, numbers, patterns, shapes, logos, and the like. As shown in Figure 4, holes 42 can also be formed in sheet 40 such that a skin remains under the indentation, hi one embodiment, the skin has a skin thickness that is less than or equal to about 5% of the sheet thickness in non-hole areas. The number of holes, hole sizes and size distribution, hole shape, hole depth, and whether or not the hole forms an opening through the sheet are all dependent upon the desired function and aesthetics of the final sheet.

[0074] hi still another embodiment, the holes can be formed so as to have a skin on all surfaces that form the holes. Holes that are formed in a cured foam sheet using a hole punch, for example, cannot have a skin. If the foam is an open-cell foam, such foams would be more prone to picking up dust, absorbing moisture, or susceptible to crumbling or tearing. Provision of a skin on all surfaces of the foam provides a foam that is less prone to dust and/or moisture absorption and/or tearing/crumbling, hi addition, the surface appearance of the holes matches the surface appearance of the foams, which leads to a pleasing appearance compared to die-cut holes that can have exposed foam that does not match the foam surface appearance. Similarly, the articles made from closed-cell foams having a skin can be more easily cleaned when compared to open-cell foam articles. [0075] Additionally, the holes can be formed to have a unique structure, as shown in the cross-section in Figure 5. In other words, a through hole 52 can have a shape similar to a punched hole, e.g., a cylindrical shape with a sharp change from the body of the sheet to the hole. A through hole 54 can also have a conical shape. In other embodiments a hole 56, 58 can be a smooth indentation that transitions gradually from the body of the sheet into the hole, e.g., slopes into the hole in a bowl- like manner, wherein the hole may (hole 58) or may not (hole 56 with skin 60 (not to scale)) extend through the sheet to form a complete opening to the other side of the sheet, hi other words, the base of the hole can be an opening through the sheet or can be a skin (e.g., having a thickness of less than or equal to about 3% of the sheet thickness in non-hole areas). If the hole is an indentation, the indentation can have a depth that is greater than or equal to about 75% of a sheet thickness, or, more specifically, greater than or equal to about 85% of the sheet thickness, or, even more specifically, greater than or equal to about 95% of the sheet thickness, and yet more specifically, greater than or equal to about 98% of the sheet thickness.

[0076] In a specific embodiment, a foam (e.g., polyurethane) sheet is provided, comprising a plurality of conical thru-holes, each extending from a first surface of the sheet through to an opposite second surface of the sheet. However, other thru-hole sizes and geometries are possible. Possible geometries include various rounded and polygonal cross-sections, such as round (e.g., cylindrical, conical, and so forth), or various rectangular and triangular cross-sections. The thru-hole geometries can be created from holes of matching geometry in one or more carrier sheets, or using shaped fluid nozzles. The foam sheets can be used in a variety of applications where functionality can be improved by having thru-holes in a foam sheet, and wherein the appearance, washability, and the like of the foam material is an important consideration. Exemplary applications can include, without limitation, footwear components, clothing components, and the like. Particular examples of footwear component applications can include, without limitation, footwear uppers, insoles, and the like. Particular examples of clothing component applications can include, without limitation, padding in athletic wear, such as jackets, pants, and the like for skiing, motocross, motorcycling, water sports, and the like. These sheets can provide both cushioning (e.g., from the foam), with breathability due to the open mesh. Moreover, these sheets can provide the aesthetic, uniform appearance that is desirable for applications such as footwear.

[0077] The following examples, which are meant to be exemplary, not limiting, illustrate foam sheets and methods of manufacturing the various embodiments of the foam sheets described herein, hi the examples, the foams were produced using mechanically frothed polyurethane foams such as those described in U.S. Patent No. 5,733,945. Also in the examples, the foam sheets as manufactured by the above described methods are compared to foam sheets produced by other methods.

Comparative Example:

[0078] An evaluation of a comparative hole-forming process for foam sheets was performed and the results detailed below. The method for the comparative example utilized a notched trowel oscillating up and down to form the holes in a foam sheet before curing. The method employed a primary "knife over plate" (KOP) configured to meter the incoming cast foam and control the sheet thickness. The foam sheet then passed under a notched trowel, which cycled in a vertical direction, to pattern the foam. The patterned foam sheet then passed under a second KOP configured to meter the final sheet thickness and remove any material build-up caused by the trowel. It was calculated that in order to achieve 2-3 holes per inch while running the test line at 10 linear feet per minute continuous line speed, the trowel actuation speed (i.e., vertical cycling) would need to be 200-300 cycles per minute. A mechanical drive assembly actuated the notched trowel and utilized an electric motor with variable speed control.

[0079] Comparative Sample 1 had a cured at a rate approximately twice as fast as the cure rate of Comparative Sample 2. The foam material of Comparative Sample 1 also had a viscosity approximately twice that of Comparative Sample 2. It was thought that the higher cure rate and cast viscosity of Comparative Sample 1 would allow for cleaner formation of the desired thru-holes and limit material flow back. The results showed, however, that while better thru-hole formation with minimal material flow back was achieved compared to Comparative Sample 2, the foam material built up on the notched trowel and caused subsequent surface defects on the final foam sheet product, particularly during prolonged production runs. The build-up can produce undesired marks on the sheet surface, as well as drop deposits onto the surface producing thickness irregularities and effecting thru-hole uniformity. By comparison, the lower cast viscosity and slower cure rate of the Comparative Sample 2 formulation reduced the amount of build-up seen on the trowel, but also created a greater tendency for material flow back into the thru-holes. The final foam sheet product of Comparative Sample 2, therefore, exhibited depressions, not true thru-holes as desired. Various trowel designs were tested to see the effect of tooth spacing, size, shape, and actuation speed on the resulting foam sheet. None of the variations were effective in improving the foam sheet product beyond that of comparative samples 1 and 2. The trowel method of this comparative example is insufficient for producing a foam sheet comprising true thru-holes as described in the specification above.

Example 1.

[0080] An evaluation of the innovative method of forming thru-holes in a foam sheet, as described throughout the specification above, was performed and the results compared to the comparative example.

[0081] The method advantageously utilized an air blown thru-hole forming process. The air was impinged onto a foam composition using an air bar. The method employed a single KOP configured to meter the incoming cast foam and control the sheet thickness. The foam sheet then passed under the air bar to pattern the foam with thru-holes. The air bar was comprised of a stainless steel tube having a 0.375 inch outer diameter, with 0.050 inch diameter air holes spaced approximately 0.190 inches apart across the length of the air bar. At this spacing, however, distortion from adjacent air holes prevented a consistent thru-hole pattern in the sheet. The spacing between each air hole, therefore, was increased. Two different air hole spacings were used for the two different formulations, and will be explained in greater detail below. Moreover, the air hole designs were straight, in other words, they had no taper. Additionally, nozzles were not used over the air holes to further modify the profile of the air bursts from the holes. A solenoid was in operative communication with the air bar and was actuated by a digital timer, such that the air bar would "fire" bursts of air at a specified rate. This specified cycle rate was varied to give the desired appearance (e.g., holes per inch on the foam sheet) based on a 10 linear feet per minute line speed. The air pressure was set from about 10 to about 15 pounds per square inch (psi) based on a cast foam layer thickness of 0.125 inches. The air bar was positioned about 0.200 inches above the surface of the cast foam layer running beneath it.

[0082] Two different foam formulations were chosen to determine how viscosity and cure rate would affect the formation and retention of the patterned holes. Sample A had a faster cure rate and slightly higher cast viscosity than that of Sample B. The two sample formulations used in the air-blown process, however, had slightly slower cure rates as compared to the formulations of comparative samples 1 and 2. The air bar for Sample A had every other air hole taped off, such that the hole spacing was 0.38 inches, rather than 0.19 inches. The resulting foam sheet, however, still showed evidence of hole distortion caused by the close proximity of the adjacent air hole. To improve the thru-hole sheet pattern, either greater hole spacing or a reduced air hole diameter would be required. In light of Sample A, the air bar for Sample B only had every fourth hole open, thereby providing a spacing of 0.76 inches. The foam sheet of Sample B has minimal thru-hole distortion and the best visual appearance of all the samples.

[0083] With the exception of the hole distortion described above, Sample A had minimal material flow back, good hole depth (as measured compared to the thickness of the cast foam sheet), and the holes retained their shape through cure. Sample A had complete thru-holes in sheets having a cast thickness of about 0.100 inches. The cast viscosity and cure rate of the formulation allowed for clean defined formation of the thru-holes when combined with the air-blown hole forming process. Sample B had a slightly slower cure rate than Sample A, which allowed for a good thru-hole formation and a "smoothing" effect on the sheet surface as the foam cured. The "smoothing" effect as described herein is to generally describe the effect of the air blast on the material. The smoothing effect is a result of the foam material's slow cure rate allowing a crater, caused by diffusion of the air in all directions when forming the thru-hole, to settle as the foam material flows back into the crater prior to curing. The result on the cured sheet is a smoothed depression aside from the thru- hole where the air from the air-bar diffused in all directions as the hole is blown through the foam. The smoothing effect is desirable as it permits a more aesthetically pleasing foam sheet having a smooth uniform surface surrounding the thru-holes. Coupled with the revised air hole spacing, the air blown hole-forming process produced a consistently patterned material having good visual appearance. The air blown hole-forming process as used in Example 1 produces a foam sheet with minimal defects, and can be adjusted to generate varied thru-hole foam surfaces, including a variety of hole sizes (e.g. diameters), shapes, spacings, frequencies, and the like. Moreover, unlike the comparative trowel method, the non-contact nature of the air blown process greatly reduces the concern for surface defects and has zero material build-up related issues. Additionally, the air blown process combined with the higher viscosity and quicker cure rate formulations helps to lock the hole pattern into the foam sheet and prevent material flow back. By comparison, the air blown hole-forming process was more efficient for producing a foam sheet with the desired surface and thru-hole quality than the trowel method utilized in the comparative example.

[0084] Ranges disclosed herein are inclusive of the recited endpoint and combinable (e.g., ranges of "up to about 25 wt%, or, more specifically, about 5 wt% to about 20 wt%", is inclusive of the endpoints and all intermediate values of the ranges of "about 5 wt% to about 25 wt%," etc.). "Combination" is inclusive of blends, mixtures, alloys, reaction products, and the like. Also, "combinations comprising at least one of the foregoing" clarifies that the list is inclusive of each element individually, as well as combinations of two or more elements of the list, and combinations of one or more elements of the list with non-list elements. Furthermore, the terms "first," "second," and so forth, herein do not denote any order, quantity, or importance, but rather are used to distinguish one element from another, and the terms "a" and "an" herein do not denote a limitation of quantity, but rather denote the presence of at least one of the referenced item. The modifier "about" used in connection with a quantity is inclusive of the state value and has the meaning dictated by context, (e.g., includes the degree of error associated with measurement of the particular quantity). The suffix "(s)" as used herein is intended to include both the singular and the plural of the term that it modifies, thereby including one or more of that term (e.g., the foam(s) includes one or more foams). Reference throughout the specification to "one embodiment", "another embodiment", "an embodiment", and so forth, means that a particular element (e.g., feature, structure, and/or characteristic) described in connection with the embodiment is included in at least one embodiment described herein, and is optionally present in other embodiments. In addition, it is to be understood that the described elements can be combined in any suitable manner in the various embodiments. As used herein, the terms sheet, film, plate, and layer, are used interchangeably, and are not intended to denote size.

[0085] All cited patents, patent applications, and other references are incorporated herein by reference in their entirety. However, if a term in the present application contradicts or conflicts with a term in the incorporated reference, the term from the present application takes precedence over the conflicting term from the incorporated reference.

[0086] While the invention has been described with reference to several embodiments thereof, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for elements thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the invention without departing from the essential scope thereof. Therefore, it is intended that the invention not be limited to the particular embodiments disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

Claims

CLAIMSWhat is claimed is:

1. A method for producing a polyurethane foam sheet, comprising:

frothing a polyurethane-forming composition comprising an isocyanate- containing component, an active hydrogen-containing component reactive with the isocyanate-containing component, a surfactant, and catalyst system;

casting the frothed reactive polyurethane-forming composition onto a first carrier to form a sheet;

impinging the sheet with a fluid at a sufficient pressure to form a hole; and

curing the frothed reactive polyurethane-forming composition to form a cured sheet comprising a hole.

2. The method of Claim 1, wherein the frothed reactive polyurethane- forming composition is partially cured prior to impinging the sheet with a fluid.

3. The method of Claim 1, further comprising placing a second carrier on a side of the cast foam opposite the first carrier; and, prior to impinging the sheet with a fluid, blowing the frothed reactive polyurethane-forming composition with the second carrier in place; and wherein the second carrier comprises an opening.

4. The method of Claim 1, wherein the first carrier comprises a release layer on a side in contact with the foam.

5. The method of Claim 1, further comprising passing the first carrier, froth, and second carrier through a thickness adjusting means.

6. The method of Claim 1, wherein the cured polyurethane foam layer includes cells having average cell diameters of about 20 to about 500 micrometer.

7. The method of Claim 1, wherein the fluid continuously impinges the sheet until partial or full cure.

8. The method of Claim 1 , further comprising heating the fluid.

9. The method of Claim 1, wherein the fluid impinges the sheet for a first duration in a first location, and then the fluid impinges the sheet for a second duration in the first location.

10. The method of Claim 1, wherein the sheet undergoes a plurality of impingements in a location.

11. The method of Claim 1 , wherein a base of the hole comprises a skin.

12. The method of Claim 1, wherein the hole extends through the sheet forming an opening.

13. An article comprising the foam of Claim 1, wherein the article is a footwear component or a clothing component.

14. The article of Claim 13, wherein the footwear component is a selected one or both of a footwear upper structure and a footwear insole.

15. The article of Claim 13, wherein the clothing component is a padding in the clothing.

16. A method for producing a foam sheet, comprising:

forming a foamed material, wherein

if the foamed material comprises a thermoset, the foamed material is uncured or partially cured;

if the foamed material comprises a thermoplastic, the foamed material is unset or partially set;

casting the foamed material onto a first carrier;

impinging the cast material with a fluid at a sufficient pressure to form a hole; and

curing the impinged material to form a sheet comprising the hole.

17. The method of Claim 16, wherein the foam material has a degree of cure or degree of solidification of less than or equal to 90%.

18. The method of Claim 16, wherein the material is selected from the group consisting of silicone, polyolefin, polyesters, polyamides, fluorinated polymers, polyalkylene oxides, polyvinyl alcohol, ionomers, cellulose acetate, polystyrene, and combinations comprising at least one of the foregoing.

19. The method of Claim 16, wherein the fluid continuously impinges the cast material until the foam material is partially or fully cured.

20. The method of Claim 16, further comprising heating the fluid.

21. The method of Claim 16, wherein the sheet undergoes a plurality of fluid impingements in a location.

22. The method of Claim 16, wherein the material comprises polyurethane.

23. An article formed by the method of Claim 22.

24. A foam sheet, comprising:

a first surface and an opposite second surface, and

a plurality of holes extending through the first surface toward the second surface;

wherein the holes have comprise a skin, a conical geometry, or a combination comprising at least one of the foregoing characteristics.

25. The article of Claim 24, wherein the foam sheet comprises a material selected from the group consisting of silicone, polyolefin, polyesters, polyamides, fluorinated polymers, polyalkylene oxides, polyvinyl alcohol, ionomers, cellulose acetate, polystyrene, and combinations comprising at least one of the foregoing.

26. The article of Claim 24, wherein the plurality of holes form a design.

27. The article of Claim 24, wherein the characteristic further comprises each of the holes has a diameter at least two times larger than the largest pore diameter of the foam.