HK1096977A - Carbon dioxide blown low density, flexible microcellular polyurethane elastomers - Google Patents

Description

Carbon dioxide foamed low density flexible microcellular polyurethane elastomers

Technical Field

The present invention relates to low density flexible microcellular elastomers suitable for use in the preparation of molded soles, insoles and midsoles; an isocyanate-reactive component useful in the production of such microcellular elastomers; an isocyanate-terminated prepolymer useful in the production of such microcellular elastomers; and a process for producing such microcellular elastomers from such isocyanate-reactive components and/or isocyanate-terminated prepolymers, in which (1) carbon dioxide is dissolved in one or both of the polyurethane-forming reaction mixture components in an amount sufficient to achieve a foam density in the one or both components of from about 0.1 to 0.8 g/cc; (2) the sum of the amounts of dissolved carbon dioxide and carbon dioxide generated in the isocyanate/water reaction is sufficient to produce a polyurethane-forming reaction mixture having a free rise density of about 0.03 to 0.3 g/cc.

Background

Resilient soles for footwear, particularly athletic footwear, are typically made from EVA (ethylene vinyl acetate copolymer) microcellular foam materials. The processing of such foams is complicated and the foam itself does not have optimum properties. However, such foams continue to be used because they have a very low density range, i.e., 0.1 to 0.35 g/cc.

Polyurethane polymers generally exhibit superior physical properties to EVA polymers. However, difficulties have been encountered when attempting to mold polyurethane microcellular elastomers of low density. Because of the hardness required for the end use, it is necessary to use a considerable amount of low molecular weight chain extender. In water-blown microcellular foams, the urea short segments produced can give formulations with poor processability, with the result that shrinkage and breakage occur in this part. The physical properties are also degraded. These problems have prevented the use of low density (< 0.35 g/cc) polyurethane microcellular elastomers, particularly very low density (< 0.30 g/cc) polyurethane microcellular elastomers.

One of the most important commercial applications for microcellular polyurethane elastomers is in the production of shoe soles. These elastomers are generally produced from isocyanate-terminated prepolymers, polyols, chain extenders, blowing agents and surfactants. The properties of these microcellular elastomers generally depend on the particular prepolymer used to prepare the elastomer (see, e.g., U.S. patent nos. 5246977 and 5849944).

U.S. patent 6458861 discloses carbon dioxide blown, low density, flexible microcellular polyurethane elastomers having a more uniform microcellular structure and improved physical properties than previously known microcellular elastomers. These improvements are the result of dissolving the carbon dioxide blowing agent in one or both of the polyurethane-forming reaction components. If water is also included as a second blowing agent, it is described in U.S. patent 6458861 that the amount of water used should be less than 50% by weight of the total amount of water required to produce a fully water blown microcellular elastomer having the same density.

Disclosure of Invention

It has been surprisingly found that low density, especially very low density, polyurethane flexible microcellular elastomers can be prepared with a blowing agent composition comprising dissolved CO₂And optionally water, wherein the dissolved CO is in an amount compared to that previously expected to be suitable for making such microcellular elastomers₂In smaller amounts, optionally in larger amounts. It has been found that dissolved CO₂The optimum amount of (A) is to dissolve CO₂The polyol and/or isocyanate component of (a) has a foam density of from about 0.1 to 0.8 g/cc, most preferably from about 0.2 to 0.4 g/cc. When dissolvedCO of₂Dissolved CO when used as blowing agent for reaction mixtures together with water₂Plus CO produced by the isocyanate/water reaction₂The amounts in combination should be sufficient to produce a polyurethane-forming reaction mixture having a free rise density of from about 0.03 to 0.3 g/cc, said reaction mixture comprising an isocyanate-reactive component that meets the criteria specified below and/or an isocyanate-terminated prepolymer that meets the criteria specified below. Polyurethanes produced according to the present invention exhibit mechanical properties, including higher hardness at low density, which makes them particularly suitable for use in sole members.

Detailed Description

The present invention relates to flexible microcellular polyurethane elastomers having a density of less than or equal to 0.3 g/cc. These microcellular elastomers are elastomeric or "rubbery" and should not be confused with microcellular rigid and semi-rigid foams made by high pressure RIM (reactive injection molding) processes commonly used to produce automotive parts, such as fenders, bumpers and instrument panels. The microcellular flexible polyurethane elastomer of the present invention should not be confused with conventional cellular flexible polyurethane foam. Conventional cellular flexible polyurethane foams have a coarse cell structure that is clearly observable to the naked eye, while microcellular elastomers have very small cells (i.e., average cell size below 200 microns, typically below 100 microns). For the microporosity of the elastomers of the present invention, it is generally only the "texture" structure that is added to the microcellular polyurethane portion that is observed, unless the portion is viewed under a microscope. Unlike microcellular elastomers, conventional polyurethane foams can generally only be made at densities below 2 pounds per cubic foot (0.17 grams per cubic centimeter) due to their large cell size.

The invention also relates to isocyanate-reactive components which are used in particular in the production of the inventive microcellular polyurethanes.

The present invention also relates to isocyanate-terminated prepolymers that are particularly useful in the production of the microcellular polyurethanes of the present invention.

The invention also relates to a process for the production of microcellular polyurethanes, in particular molded microcellular polyurethanes, in which process carbon dioxide is dissolved in the isocyanate-reactive component and/or the isocyanate-terminated prepolymer of the invention, the amount of carbon dioxide being such that CO is dissolved₂Has a foam density of about 0.1 to 0.8 g/cc, and CO in the polyurethane-forming reaction mixture₂Total amount of (i.e. dissolved CO)₂Plus CO produced in the reaction of isocyanate with water₂The sum of the amounts) should be such that the foam-forming mixture has a free rise density of about 0.03 to 0.3 g/cc.

The term "polyurethane" as used herein refers to polymers having a structure that predominantly contains urethane (-NH-CO-O-) linkages, which polymers may also contain small amounts (i.e., less than 5%) of allophanate, biuret, carbodiimide, oxazoline, isocyanurate, uretdione (uretdione), urea and other linkages between repeat units in addition to urethane linkages.

The microcellular polyurethane elastomers are prepared by reacting an isocyanate component with an isocyanate-reactive component. In addition, various additives and processing aids may be present, such as surfactants, catalysts, stabilizers, pigments, fillers, and the like. Suitable additives and processing aids are well known to those skilled in the art of flexible microcellular polyurethane elastomers. A blowing agent is also necessary. However, CFC blowing agents used for many years have been replaced and water is now beginning to be the primary blowing agent for such foams. However, in the present invention, both dissolved carbon dioxide and water are used as the blowing agent.

The isocyanate component of the microcellular elastomer "system" or "formulation" generally comprises an isocyanate-terminated prepolymer in a major component. Such prepolymers are well known and can be prepared by catalytic or non-catalytic reaction of a stoichiometric excess of at least one diisocyanate or polyisocyanate with a polyol. Examples of readily available isocyanates which are also commonly used in the production of such prepolymers include Toluene Diisocyanate (TDI), particularly 2, 4-toluene diisocyanate (2, 4-TDI), diphenylmethane diisocyanate (MDI), particularly 4, 4 '-diphenylmethane diisocyanate (4, 4' -MDI), polymeric MDI and modified MDI. Any other known isocyanate, including mixtures of isocyanates, may also be used.

The polyol component used to prepare the prepolymer or prepolymers typically has a functionality of between 2.0 and 4.0, although polyol components having a functionality of greater than 4.0 or less than 2.0 may also be used. The isocyanate content of the prepolymer (expressed as the weight percent of isocyanate groups or "% NCO") may be between 5% and 30%, but is preferably in the range of 15% to 25%. Most preferably, the isocyanate content of the prepolymer used in the sole product is in the range of about 18% to 22%.

The isocyanate component used in the practice of the present invention may include: (1) a single prepolymer; or (2) a mixture of prepolymers; or (3) a combination of the prepolymer and an isocyanate or modified isocyanate. Isocyanates or modified isocyanates that may be present in the isocyanate component of the present invention include: "monomeric" isocyanates, such as any TDI isomer and isomer mixture, any MDI isomer and isomer mixture; polymeric MDI and/or modified isocyanates containing urethane, urea, allophanate groups, especially carbodiimide groups and the like. Such isocyanates are well known and may be used alone or as mixtures. Aliphatic isocyanates, such as isophorone diisocyanate, can be used, but they are not preferred. Mixtures of prepolymers and "monomeric" isocyanates may also be used. When the isocyanate component consists of (a) a mixture of at least one prepolymer and at least one monomeric isocyanate or (b) consists of only one or more monomeric isocyanates, the total isocyanate content of the isocyanate component may exceed 25%.

In preparing the prepolymer to be included in the isocyanate component, any known hydroxyl functional material may be used. Polyether polyols, polyester polyols, polyether-polyester hybrid polyols and mixtures or combinations thereof are preferably used. The hydroxyl functionality of the hydroxyl functional material or materials used to produce such prepolymers is generally from 1.2 to 8, preferably from 2 to 4, and most preferably from 2 to 3, although higher functionalities may also be used, it is preferred to use small amounts of such high functionality materials. Sometimes a mixture of low functionality and high functionality polyols is advantageous. The functionality described herein is the theoretical functionality based on the number of active hydrogens contained in the starting molecules (preferably polyether polyols or polyester polyols or polyether-polyester hybrid polyols) from which the hydroxy-functional material is made. That is, for any given polyol, the theoretical functionality will be an integer. Mixtures of such polyols, for example, polyols produced from mixtures of di-and tri-functional starter molecules, have theoretical functionalities between those of the starter. For example, a polyol made from equimolar amounts of ethylene glycol and glycerol has a theoretical functionality of 2.5.

The theoretical functionality of the polyol must be distinguished from the actual or measured functionality, the latter generally being less than theoretical in the case of polyether polyols, since side reactions can occur during the polyoxyalkylation reaction. For example, a polyether diol having a molecular weight of 3000 daltons (Da) has a theoretical functionality of 2. If conventionally prepared by base-catalyzed alkoxylation, the actual functionality may be 1.6, whereas if prepared using low unsaturation polyalkoxylation techniques, the actual functionality may be 1.85 to about 1.97.

Particularly preferred isocyanate-terminated prepolymers useful in producing the microcellular polyurethanes according to the present invention have an NCO content of from 5% to 30%, preferably from 15% to 25%, which is the reaction product of (1) a diisocyanate and/or polyisocyanate with (2) a polyol having a hydroxyl functionality of from 1.2 to 8 and a number average molecular weight of less than 3000 daltons and optionally (3) a chain extender. Preferred polyols for producing these prepolymers include polyether polyols having an ethylene oxide content of about 0 to 30%, and mixtures of one or more diols with one or more triols. Specific examples of such polyols are given below. The diisocyanate or polyisocyanate used to prepare these prepolymers is preferably diphenylmethane diisocyanate ("MDI") or polymeric MDI. Preferred chain extenders for the production of these prepolymers include diols, particularly dipropylene glycol.

When an isocyanate-terminated prepolymer which is the reaction product of a diisocyanate or polyisocyanate and a polyol having a hydroxyl functionality of 1.2 to 8 and a number average molecular weight of less than 3000 is used to produce the microcellular polyurethane according to the present invention, any known isocyanate-reactive compound may be used to produce the microcellular polyurethane elastomer according to the present invention. Examples of such isocyanate-reactive compounds include polyether polyols, polyester polyols and hybrid polyether-polyester polyols. However, it is preferred to use the isocyanate-reactive components of the present invention as described more fully hereinafter.

While the isocyanate-reactive component of the present invention may comprise any polyol having a hydroxyl functionality of at least 1.7 and a molecular weight of from about 1000 to 12000Da, it is preferred that the isocyanate-reactive component used to produce the microporous polyurethane of the present invention comprises: (a) at least one polyol, preferably at least one polyether, polyester or mixed polyether-polyester polyol having a functionality of about 2 and a molecular weight of about 1000 to 12000, preferably about 1500 to 6000; (b) at least one polyol, preferably at least one polyether, polyester or mixed polyether-polyester polyol having a functionality of about 3 and a molecular weight of about 1000 to 12000, preferably about 3000 to 6000. Additionally, polyols made from mixed functional starting materials having a molecular weight of about 1000 to 12000, preferably about 1500 to 6000, and a functionality of about 1.2 to 8, preferably about 2 to 4, may optionally be used. Polyether polyols are particularly preferred for use in the practice of the present invention. In addition to the desired difunctional and trifunctional polyols, any other known isocyanate-reactive materials may also be included in the polyol component.

When the preferred isocyanate-reactive component of the present invention is used to produce microcellular polyurethanes, any of the known diisocyanates and/or polyisocyanates may be used. However, it is preferred that the isocyanate be an isocyanate-terminated prepolymer as described above, which is particularly advantageous in the practice of the present invention.

Any material having two or more hydroxyl groups and a molecular weight of at least about 1000 may be included in the isocyanate-reactive component used in the practice of the present invention. Such materials include polyols such as polyester polyols, polyether-polyester hybrid polyols, polyhydroxy polycarbonates, polyhydroxy polyacetals, polyhydroxy polyacrylates, polyhydroxy polyester amides and polyhydroxy polythioethers. Preferred are polyester polyols, polyether polyols and polyhydroxy polycarbonates.

Suitable polyester polyols include the reaction products of polyhydric alcohols, preferably dihydric alcohols to which trihydric alcohols may be added, with polyhydric, preferably dibasic, carboxylic acids. In addition to these polycarboxylic acids, the corresponding carboxylic anhydrides or polycarboxylic esters of lower alcohols or mixtures thereof may also be used to prepare the polyester polyols useful in the practice of the present invention. The polycarboxylic acids may be aliphatic, cycloaliphatic, aromatic and/or heterocyclic, which may be substituted, for example, by halogen atoms, and/or unsaturated. Examples of suitable polycarboxylic acids include: gluconic acid (gluccinicacid); succinic acid; adipic acid; suberic acid, azelaic acid; sebacic acid; phthalic acid; isophthalic acid; trimellitic acid; phthalic anhydride; tetrahydrophthalic anhydride; hexahydrophthalic anhydride; tetrachlorophthalic anhydride, endomethylenetetrahydrophthalic anhydride; glutaric anhydride; maleic acid; maleic anhydride; fumaric acid; dimeric and trimeric fatty acids, such as oleic acid, which may be mixed with monomeric fatty acids; dimethyl terephthalate and bis (glycol) terephthalate; suitable polyols include: ethylene glycol; 1, 2-and 1, 3-propanediol; 1, 3-and 1, 4-butanediol; 1, 6-hexanediol; 1, 8-octanediol; neopentyl glycol; cyclohexanedimethanol; (1, 4-bis (hydroxymethyl) cyclohexane); 2-methyl-1, 3-propanediol; 2, 2, 4-trimethyl-1, 3-propanediol; triethylene glycol; tetraethylene glycol; polyethylene glycol; dipropylene glycol; polypropylene glycol; dibutylene glycol and polybutylene glycol, glycerol and trimethylolpropane. The polyester may also contain a portion of terminal carboxyl groups. Polyesters of lactones, such as epsilon-caprolactone, or of hydroxycarboxylic acids, such as omega-hydroxycaproic acid, may also be used.

Suitable polycarbonates containing hydroxyl groups include those obtained by reacting diols with phosgene, diaryl carbonates (e.g., diphenyl carbonate) or cyclic carbonates (e.g., ethylene or propylene carbonate). Examples of suitable diols include: 1, 3-propanediol; 1, 4-butanediol; 1, 6-hexanediol; diethylene glycol; triethylene glycol; tetraethylene glycol. Polyester carbonates obtained by reacting polyesters or polylactones (as described above) with phosgene, diaryl carbonates or cyclic carbonates may also be used in the practice of the present invention.

Polyether polyols suitable for use in the practice of the present invention include those obtained by reacting one or more starting compounds containing active hydrogen atoms with alkylene oxides, such as ethylene oxide, propylene oxide, butylene oxide, styrene oxide, tetrahydrofuran, epichlorohydrin or mixtures of such alkylene oxides, in a known manner. Suitable active hydrogen atom-containing starting compounds include polyols (described above as being suitable for use in preparing polyester polyols); water; methanol; ethanol; 1, 2, 6-hexanetriol; 1, 2, 4-butanetriol; trimethylolethane; pentaerythritol; mannitol; sorbitol; methyl glucoside; sucrose; phenol; isononyl phenol; resorcinol; hydroquinone; and 1, 1, 1-or 1, 1, 2-tris- (hydroxyphenyl) -ethane.

The diols and triols present in the preferred isocyanate-reactive component used to produce the microcellular polyurethanes according to the present invention are preferably present in an amount such that the weight ratio of diol to triol in the isocyanate-reactive component (based on the total weight of diol and triol) is preferably from about 60 to 100 weight percent diol to about 10 to 40 weight percent triol, most preferably from about 80 to 90 weight percent diol to about 10 to 20 weight percent triol.

Other polyether and/or polyester polyols than diols or triols, such as those having a functionality of greater than 3 or a molecular weight of less than 1000 or greater than 12000, which are required to practice the preferred embodiment of the present invention, may also be included in the reaction mixture, these other polyols should be present in minor amounts, i.e., in an amount of less than 30% by weight, preferably less than 20% by weight, based on the total weight of the isocyanate-reactive components. When such optional materials are included in the isocyanate-reactive component, the ratio of diol to triol needs to be adjusted to maintain the proper crosslink density of the polyurethane. Such adjustments are within the ability of those skilled in the art, and the extent to which the diol-to-triol ratio must be adjusted can be determined according to techniques known to those skilled in the art.

The isocyanate-reactive component of the present invention also typically includes a chain extender, a surfactant, and a catalyst. Typically, the chain extender included in the isocyanate-reactive component has a functionality of about 2 and a molecular weight of no more than 300 Da. Suitable chain extenders include: ethylene glycol; 1, 2-and 1, 3-propanediol; 1, 4-butanediol; 1, 6-hexanediol; diethylene glycol; dipropylene glycol; neopentyl glycol; 2-methyl-1, 3-propanediol. Because the amount of chain extender is small, it is generally not necessary to adjust the ratio of diol to triol in the isocyanate-reactive component. Suitable surfactants and catalysts are known to those skilled in the art and are discussed below.

Regardless of the chain extender or any other isocyanate-reactive group containing additive or processing aid, the total average equivalent weight of the polyol component is generally in the range of about 1000Da to 12000Da, preferably in the range of 1000Da to 3000Da, more preferably in the range of about 1500Da to 2000 Da. However, higher equivalent weight polyether polyols may also be used. The average theoretical functionality is generally between 1.5 and 4, more preferably between 2 and 3.

In addition to polyether polyols and polyether-polyester hybrid polyols, the isocyanate-reactive component may also include, and preferably includes, a "polymer polyol". Polymer polyols are polyols containing dispersed polymer particles. While many polymer polyols are theoretically possible and are available in many varieties, the most preferred polymer polyols are those prepared by in situ polymerization of unsaturated molecules in a base polyol, often with the aid of an unsaturated "macromer" polyol. The unsaturated monomers are most commonly acrylonitrile and styrene, and the acrylonitrile/styrene copolymer particles are preferably stably dispersed in an amount of 10 to 60 weight percent, more preferably 20 to 50 weight percent, and most preferably 30 to 45 weight percent, based on the total weight of the polymer polyol. Such polymer polyols are commercially available. For example, ARCOL ® E850, which contains 43% polyacrylonitrile/polystyrene solids, is commercially available from Bayer MaterialScience. Polymer polyols having urea particles dispersed therein, such as Multranol 9151 polyol, also commercially available from Bayer MaterialScience, are also particularly suitable for use in the isocyanate-reactive component of the present invention. When included in the isocyanate-reactive component, the polymer polyol is considered to be a triol for purposes of calculating the diol/triol ratio.

When a polymer polyol is included in the isocyanate-reactive component, the use of a chain extender may not be required, and thus the chain extender may be omitted from the isocyanate-reactive component. If a polymer polyol is used, it is generally present in the isocyanate-reactive component in an amount of less than 20% by weight, based on the total weight of the microcellular elastomer. However, high levels of polymer polyol can be used without adversely affecting product performance.

CO prepared according to the invention with polyols having low unsaturation (i.e. less than 0.20meq/g) or ultra-low unsaturation (i.e. less than 0.010meq/g)₂The foamed microcellular polyurethanes exhibit high hardness at very low densities. Polyether polyols of ultra-low unsaturation are available from Bayer MaterialScience under the trade names Accuflex ® and Acclaim ® polyether polyols. The unsaturation of these Bayer polyols is generally in the range of 0.002meq/g to 0.007 meq/g.

As used herein, "high hardness" means having a relatively high hardness as compared to a conventional foamed (CFC-foamed) microcellular elastomer of similar density. Although these very low density elastomers have a relatively high hardness, the hardness values of these elastomers are still much lower than their corresponding water-blown counterparts. The hardness of water-blown elastomers, particularly at low densities, makes such microcellular elastomers unsuitable for use in footwear.

The hardness range of the microcellular elastomers of the present invention is suitable for use in soles, particularly for use in midsole applications. Preferably, the hardness is at least 40(Asker C) when the density of the portion is equal to or less than about 0.22 g/cc and at least 50(Asker C) when the density is equal to or less than about 0.3 g/cc. High hardness foams, such as those having a hardness of 75 or greater on the Asker C scale, are preferably avoided for use in midsole applications.

Additives that may be added to the microcellular elastomer formulation are known to those skilled in the art and include surfactants, fillers, dyes, pigments, ultraviolet stabilizers, oxidation stabilizers, catalysts, and the like.

Surfactants suitable for maintaining the stability of very fine pores are often used. Examples of suitable commercially available surfactants include Dabco ® SC5980, a silicone surfactant available from Air Products co; dabco DC-5258, a silicone surfactant available from Air Products Co.; dabco DC-5982, a modified polyether polysiloxane available from Air Products Co; NIAXL-5614, a silicone surfactant available from GE Silicones; SH-8400, a polyether modified siloxane compound available from Toray Silicone Company, Ltd.; TegostabB8870, a surfactant commercially available from Goldschmidt; tegostab B8905, a modified polyether polysiloxane available from Goldschmidt; tegostab B8315, a modified polyether polysiloxane available from Goldschmidt; and Irgastab PUR 68, a mixture of esters and benzofuranones available from Ciba specialty Chemicals Corporation. Any other surfactant known to those skilled in the art is also suitable.

Suitable fillers include: fumed or precipitated silica, quartz flour, diatomaceous earth, precipitated or ground calcium carbonate, alumina trihydrate and titanium dioxide.

Any conventional polyurethane catalyst (i.e., a catalyst that promotes the reaction of isocyanate with polyol) and a catalyst that catalyzes the isocyanate/water reaction may be used. Examples of suitable polyurethane catalysts include various tin catalysts, specifically tin octoate, dibutyltin dichloride, dibutyltin diacetate, and dibutyltin dilaurate, and dimethyltin dithiolate; bismuth catalysts such as bismuth nitrate; tertiary amine catalysts, such as triethylenediamine. These polyurethane catalysts are generally present in the isocyanate-reactive component in an amount of from about 0.01 to about 5 parts by weight, preferably from about 0.1 to about 3 parts by weight, based on the total weight of the polyol in the isocyanate-reactive component.

Examples of suitable isocyanate/water reaction catalysts include bis (dimethylaminoethyl) ether in dipropylene glycol, which is commercially available from GE Silicones under the tradename Niax A1. The amount of these water/isocyanate catalysts in the isocyanate-reactive component is generally from about 0.05 to about 5 parts by weight, preferably from about 0.1 to about 1 part by weight, based on 100 parts of polyol. It is preferred to use a catalyst which catalyzes both the carbamate and isocyanate/water reactions, since only one catalyst is required. Triethylene diamine is an example of a catalyst that catalyzes both the urethane and isocyanate/water reactions, and is generally present in the isocyanate-reactive component in an amount of from about 0.1 to about 5 parts by weight, preferably from about 0.5 to about 2 parts by weight, based on the total weight of the polyol.

Reactive elastomer formulations are generally formulated at an isocyanate index of from about 90 to 120, preferably from about 95 to 105, and most preferably about 100.

The microcellular elastomers of the present invention are foamed with carbon dioxide. A portion of the carbon dioxide is in gaseous form that dissolves as a gas under pressure in at least one of the isocyanate or isocyanate-reactive component. Gaseous carbon dioxide may be dissolved in one or both of the isocyanate and isocyanate-reactive components. Preferably, carbon dioxide is dissolved in the isocyanate-reactive component. The remainder of the carbon dioxide is generated during the polyurethane-forming reaction from the reaction of water present in the isocyanate-reactive component with the isocyanate. The amount of carbon dioxide gas dissolved in one or both of the reaction components is generally sufficient to provide a foam density of about 0.1 to 0.8 g/cc, preferably about 0.2 to 0.4 g/cc. The amount of water in the isocyanate-reactive component should be that amount necessary to generate sufficient carbon dioxide to replenish dissolved carbon dioxide so that the free rise density of the foam-forming mixture is from about 0.03 to about 0.3 grams per cubic centimeter, preferably from about 0.09 to about 0.2 grams per cubic centimeter. The desired free rise density is about half the density of the flexible microcellular polyurethane product.

For example, if the desired density of the flexible microcellular polyurethane product is 0.2 g/cc, the free rise density of the polyurethane-forming reaction mixture should be about 0.1 g/cc.

If too much water is present in the isocyanate-reactive component, or if too much water is added to the isocyanate-reactive component, the number of urea linkages in the product will increase and the Ross flex fatigue performance will decrease. For example, adding 1.3% water to the polyurethane-forming reaction mixture will produce an elastomer with a cold ross deflection of about 70000 weeks (cycles), while adding only 1.1% water to the reaction mixture will produce an elastomer with a cold ross deflection of greater than 100000 weeks.

Carbon dioxide gas to be dissolved in the reaction components is introduced into the component tanks of the foaming apparatus at moderate pressure and for a sufficient time to achieve the desired degree of dissolution. The amount of dissolution can be measured by any convenient technique, including the relative rate of diffusion through a membrane detector. The amount of dissolution is in the range of 0.2 to 4 g/l, preferably 0.5 to 2 g/l, more preferably 0.7 to 1.2 g/l. Dissolved CO₂The higher the amount, the lower the component density. Carbon dioxide may be added to the tank in a convenient manner at a pressure of 50psi and given sufficient time to dissolve the desired amount of carbon dioxide. Unless otherwise stated, dissolved CO₂The amount of (A) is based on the average of the amounts of isocyanate and isocyanate-reactive componentThe concentration is given in grams/liter.

Although any other known blowing agents, such as HFCs, HCFC's, and hydrocarbons such as pentane, may be used in small amounts (e.g., less than 20% of the total blowing agent composition), the use of these known blowing agents is not preferred.

Also included within the scope of the invention are gases such as air and nitrogen in the vessel or chamber in which the polyurethane-forming reaction is carried out. Use of such gases for controlling CO in a headspace₂Is particularly advantageous.

Two or more reactant streams, typically an isocyanate-reactive component stream and an isocyanate stream, may be combined by any suitable method for preparing microcellular elastomers, including mixing in a low or high pressure mixing head. A low pressure shoe sole molding machine (i.e., Desma RGE 395) is preferably used. When carrying out the invention, the isocyanate-reactive component stream and/or the isocyanate component stream must already contain dissolved CO₂. Adding CO only to the mixing head or to the foaming machine (e.g. Oakes mixer)₂And does not result in an acceptable microcellular elastomer.

Advantages of the process of the present invention include the considerable reduction in the amount of chain extender used in the production of low density microcellular elastomers, which increases the processing window and reduces shrinkage and breakage. The high hardness of the very low density microcellular elastomers produced in accordance with the present invention is in the range suitable for use in sole components, while the all water blown microcellular foams have unacceptably high hardness.

Having generally described the invention, a further understanding can be obtained by reference to certain specific examples which are provided herein for purposes of illustration only and are not intended to be limiting.

Examples

The materials used in the examples are as follows:

PPOL A: an NCO-terminated prepolymer having an NCO content of 19.8% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL B: an NCO-terminated prepolymer having an NCO content of 19.7% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL C: an NCO-terminated prepolymer having an NCO content of 20% prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL D: an NCO-terminated prepolymer having an NCO content of 19.6% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL E: an NCO-terminated prepolymer having an NCO content of 19.77% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL F: an NCO-terminated prepolymer having an NCO content of 19.73% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL G: an NCO-terminated prepolymer having an NCO content of 19.53% was prepared by reacting POLY K, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL H: an NCO-terminated prepolymer having an NCO content of 20% prepared by reacting POLY L, dipropylene glycol and diphenylmethane diisocyanate.

PPOL I: an NCO-terminated prepolymer having an NCO content of 19.59% was prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL J: NCO-terminated polyester prepolymer having an NCO content of 18.9% and available under the trade name Mondur 501 from Bayer MaterialScience LLC.

PPOL K: an NCO-terminated prepolymer having an NCO content of 19.2% was prepared by reacting dipropylene glycol, POLYA and diphenylmethane diisocyanate.

PPOL L: an NCO-terminated prepolymer having an NCO content of 17.4% was prepared by reacting dipropylene glycol, POLYH and diphenylmethane diisocyanate.

PPOL M: an NCO-terminated prepolymer having an NCO content of 19.85% was prepared by reacting dipropylene glycol, POLYD and diphenylmethane diisocyanate.

PPOL N: an NCO-terminated prepolymer having an NCO content of 17.85% was prepared by reacting dipropylene glycol, POLYD and diphenylmethane diisocyanate.

PPOL O: an NCO-terminated prepolymer having an NCO content of 18.0% and prepared by reacting dipropylene glycol, POLYD and diphenylmethane diisocyanate.

PPOL P: an NCO-terminated prepolymer having an NCO content of 17.3% was prepared by reacting 6 parts by weight of dipropylene glycol, 26.6 parts by weight of POLY M, 62 parts by weight of NCO A, and 5.4 parts by weight of NCO B.

PPOL Q: an NCO-terminated prepolymer having an NCO content of 17.3% was prepared by reacting 6 parts by weight of dipropylene glycol, 25.3 parts by weight of POLY N, 63.2 parts by weight of NCO A, and 5.5 parts by weight of NCO B.

PPOL R: an NCO-terminated prepolymer having an NCO content of 17.6% was prepared by reacting 6 parts by weight of dipropylene glycol, 26.7 parts by weight of POLY A, 61.9 parts by weight of NCO A, and 5.4 parts by weight of NCO B.

PPOL S: an NCO-terminated prepolymer having an NCO content of 17.8% was prepared by reacting 6 parts by weight of dipropylene glycol, 25.7 parts by weight of POLY D, 62.9 parts by weight of NCO A, and 5.5 parts by weight of NCO B.

PPOL T: an NCO-terminated prepolymer having an NCO content of 18% prepared by reacting POLY A, dipropylene glycol, and diphenylmethane diisocyanate.

PPOL U: an NCO-terminated prepolymer having an NCO content of 15% prepared by reacting POLY M with diphenylmethane diisocyanate.

PPOL V: an NCO-terminated prepolymer having an NCO content of 18% prepared by reacting POLY O with diphenylmethane diisocyanate.

POLY A: an ethylene oxide capped (capped) polyether diol having a molecular weight of 4000Da and a hydroxyl number of 28 is commercially available from Bayer MaterialScience under the trade name Acclaim 4220.

POLY B: an ethylene oxide-capped polyether triol having a molecular weight of 6000Da and a hydroxyl number of 28 and available from Bayer MaterialScience under the trade name Acclaim 6320.

POLY C: a polyether diol based on propylene oxide having a molecular weight of 8000Da and a hydroxyl number of 14 is available from Bayer MaterialScience under the trade name Acclaim 8220.

POLY D: polyether diols having a molecular weight of 2000Da and a hydroxyl number of 28, available under the trade name Acclaim2220 from Bayer MaterialScience LLC.

POLY E: a polyethylene oxide modified polypropylene oxide triol having a molecular weight of 6000Da and a hydroxyl number of 28 is available under the trade name Multranol 9139 from Bayer MaterialScienceLLC.

POLY F: ethylene oxide modified polypropylene oxide based glycols having a molecular weight of 4000Da and a hydroxyl number of 28 are available from Bayer MaterialScience LLC under the trade name Multranol 9190.

POLY G: polyurea filled polyether polyols are available from Bayer MaterialScience LLC under the trade name Multranol 9159.

POLY H: polyethylene oxide modified polypropylene oxide glycol having a molecular weight of 4000Da and a hydroxyl number of 28 is commercially available from Bayer MaterialScience under the trade name Multranol 9111.

POLY I: polymer polyol containing 43% by weight of polyacrylonitrile/polystyrene as the dispersed phase is available from Bayer MaterialScience under the trade name Arcol E850.

POLY J: triol-based polyether polymer polyols having a hydroxyl number of 27 are available from Bayer MaterialScience LLC under the trade designation Arcol 34-28.

POLY K: EO/PO polyether diol having a hydroxyl number of 80 and a designation A1205.

POLY L: propylene oxide/ethylene oxide Polyol having a hydroxyl number of 28, available from Bayer MaterialScience under the trade name Arco Polyol 1027.

POLY M: propylene oxide based diol polyols having a molecular weight of 4000Da and a hydroxyl number of 28 are commercially available from Bayer MaterialScience under the trade name Acclaim 4200.

POLY N: polyether diol having a hydroxyl number of 56, commercially available from bayer materialscience under the trade name Acclaim 2200.

POLY O: an ethylene oxide containing polyether diol having a molecular weight of 3000Da and an hydroxyl number of 35 is commercially available from Bayer MaterialScience under the trade name Acclaim Polyol 3205.

BD: butanediol.

EG: ethylene glycol.

NCO A: 4, 4' -diphenylmethane diisocyanate, available from Bayer MaterialScience under the trade name Mondur M.

NCO B: carbodiimide-modified diphenylmethane diisocyanate, commercially available from Bayer MaterialScience under the trade name Mondur CD.

CAT A: a33% strength ethylene glycol solution of an amine catalyst is available from Air Products under the trade name Dabco EG.

CAT B: heterocyclic amines in diols are available from Air Products under the trade name Dabco 1027.

And CAT C: dioctyltin dithiolate, available under the trade name Foamrez UL-32 from Witco Corporation.

CAT D: n, N-dimethyl-4-morpholinoethylamine (ethylamine) is available from Air Products under the trade name Dabco XDM.

CAT E: dioctyltin dithiolate, available from Crompton under the tradename Fomrez UL 32.

CAT F: dibutyl tin dilauryl mercaptide, available from Air Products under the trade name DABCO T120.

CAT G: pentamethyldiethylenetriamine commercially available from Air Products under the tradename PolyCat 5.

T571: benzotriazole-based ultraviolet light absorbers are commercially available from ciba geigy under the tradename Tinuvin 571.

T765: bis (1, 2, 2, 6, 6-pentamethyl-4-piperidinyl) sebacate, available from Ciba Geigy under the tradename Tinuvin 765.

T101: ethyl 4- (((methylphenylamino) methylene) amino) -benzoate, available from Ciba Geigy under the tradename Tinuvin 101.

SURF A: silicone surfactants available from Air Products under the trade name DABCO DC-5258.

SURF B: silicone surfactants available from GE Silicone under the tradename NIAX L-5614.

SURF C: modified polyether polysiloxanes are commercially available from Air Products under the trade name DABCO DC 5980.

SURF D: polyether modified siloxane compounds are commercially available from Toray Silicone Company under the trade name SH-8400.

SURF E: modified polyether polysiloxanes are commercially available from Air Products under the trade name DABCO DC-5982.

SURF F: modified polyether polysiloxanes are available from Goldschmidt under the trade name Tegostab B8870.

SURF G: a mixture of esters and benzofuranones is available from Ciba Specialty Chemicals Corporation under the trade name IRGASTAB PUR 68.

SURF H: modified polyether polysiloxanes are available from Goldschmidt under the trade name Tegostab B8905.

SURF I: modified polyether polysiloxanes are available from Goldschmidt under the trade name Tegostab B8315.

General procedure

The following steps are used in the examples hereinafter.

The prepolymers listed in the table were added to the isocyanate tank of the low-pressure shoe sole molding machine. The polyol component obtained from the components listed in the table was added to the polyol tank.

Introducing CO₂Dissolved in the polyol component in the amounts shown in the table at the pressures shown in the table. The isocyanate and isocyanate-reactive components were mixed in the NCO/OH ratios listed in the table while the tanks were maintained at 50psi and 35 ℃. The mixture was molded into shoe soles having the molding densities indicated in the table.

The foam densities listed in the table below are dissolved CO only₂Brought about and measured by taking a sample of the resin, foaming it completely and then measuring its density. It is important to note that, unlike air nucleation, which is commonly used in polyurethane foams, dissolved CO is used₂The resulting foam is a stable foam that does not collapse as would be the case with air.

All amounts of materials used in the following examples are in parts by weight.

Examples 1 to 6

These examples illustrate microcellular elastomers made with varying relative amounts of diols and triols in the polyol component.

TABLE 1

Examples	1	2	3	4	5	6
							POLY A	74.9	74.9	46.5	74.5	74.55	64.25
POLY B	25.1	25.1	53.5	25.5	25.45	5.5
							POLY I	0	0	0	0	0	30.25
BD	23.77	23.77	10.72	0	8.46	30.25
							EG	0	0	14.79	18.02	11.67	12.6
Water (W)	0	0	0	0	0	1.68
							CAT A	0.45	0.45	0.2	0.2	0.2	0.4
CAT B	0.34	0.34	0.3	0.3	0.3	0.3
							CAT C	0.23	0.23	0.01	0.01	0.01	0.02
SURF A	0.45	0.45	0	0	0	0
							SURF B	0	0	0.4	0	0	0
SURF C	0	0	0	2.0	2.0	2.0
							PPOL	A	A	B	C	C	D
NCO/OH	1.01	1.01	1.31	1.12	1.07	1.2
							D-CO2(g/l)1	1.27	1.60	---	---	---
Examples	1	2	3	4	5	8
							FD(g/cc)2	0.363	0.2	---	---	---	---
FRD(g/cc)3	0.28	0.18	---	---	---	---
							MD(g/cc)4	0.45	0.22	---	---	---	---
Hardness of5	85	67	---	---	---	72
							C tear kg/cm	19	9.8	---	---	---	---
Tear separation kg/cm	7.0	2.6	---	---	---	---
							Rebound resilience%	30	28	---	---	---	---
TStr.(kg/cm2)6	26	10.5	---	---	---	---
							% elongation	130	88	---	---	---	---

¹D-CO₂CO dissolved in polyol₂

²FD ═ foam density of polyol component

³FRD water + dissolved CO₂Resulting% free rise density

⁴MD ═ molded density

⁵Hardness ofAsker C hardness

⁶TStr-tear Strength

Examples 7 to 9

These examples illustrate the production of microcellular polyurethanes according to the invention using polyol components in which the molecular weight of the diol is lower than that of the diols used in examples 1 to 6.

TABLE 2

Examples	7	8	9
				POLY C	42.6	44.3	45.31
POLY B	28.35	29.8	51.47
				POLY D	0	2.84	3.22
POLY I	29.05	25.9	0
				EG	14.14	9.9	13.57
Water (W)	1.0	1.34	1.54
				CAT A	0.4	0.63	0.63
CAT B	0.3	0	0
				CAT C	0.02	0	0
CAT D	0	0.3	0.3
				SURF C	1.0	1.0	1.0
SURF D	0	0.4	0.4
				PPOL	G	E	A
Examples	7	8	9
				NCO∶OH	1.14	0.95	1.2
D-CO2(g/1)1	1.61	1.27	1.5
				FD(g/cc)2	0.189	0.363	0.246
FRD(g/cc)3	0.110	0.116	0.099
				MD(g/cc)4	0.206	0.205	0.20
Hardness of5	76	60	61
				C tear kg/cm	9.3	7.1	6.0
Tear separation kg/cm	2.4	1.9	2.3
				Rebound resilience%	21	28	29
TStr(kg/cm2)6	18.4	17.1	14.2
				% elongation	121	192	155

^1-6The same meanings as in Table 1

Examples 10 to 11

These examples illustrate the use of two different polyol components, each comprising a polymer polyol, to produce a microcellular polyurethane according to the present invention.

TABLE 3

Examples	10	11
			POLY M	44.0	0
POLY E	29.9	0
			POLY B	0	29.78
POLY F	0	41.57
			POLY I	26.1	25.86
EG	9.0	8.64
			Water (W)	1.34	1.0
CAT A	1.26	0.4
			CAT B	0.4	0.3
CAT D	0.4	0.4
			SURF D	0.4	0.4
SURF E	1.0	1.0
			PPOL	H	F
NCO∶OH	0.97	0.96
			D-CO2(g/l)1	1.27	1.30
FD(g/cc)2	0.39	0.38
			FRD3	0.1	0.09
Examples	10	11
			MD(g/cc)4	0.22	0.22
TStr(kg/cm2)6	17.9	20.7
			% elongation	189	205
Hardness of5	63	53
			C tear (kg/cm)	9.5	8.2
Tear separation (kg/cm)	2.2	1.6
			Rebound resilience (%)	20	20

^1-6The same meanings as in Table 1

Examples 12 to 15

These examples illustrate the use of a polyol component containing a polymer to produce a microcellular polyurethane according to the present invention.

TABLE 4

Examples	12	13	14	15
					POLY C	41.84	41.84	41.84	41.84
POLY B	29.63	29.63	29.63	29.63
					POLY I	25.76	25.76	0	25.76
POLY D	2.77	2.77	2.77	2.77
					POLY G	0	0	25.76	0
EG	8.63	8.68	8.68	8.63
					Water (W)	1.33	1.33	1.33	1.33
CAT A	1.26	1.26	1.26	1.5
					CAT B	0.4	0.4	0.4	1.2
CAT D	0.3	0.3	0.3	0.7
					CAT E	1.06	1.06	1.06	1.06
CAT F	0.53	0.53	0.53	0.53
					SURF D	0.4	0.4	0.4	0.4
SURF E	1.0	1.0	1.0	1.0
					PPOL	I	J	J	K
NCO∶OH	0.94	0.97	0.98	0.99
					Examples	12	13	14	15
D-CO2(g/l)1	1.2	1.02	1.02	---
					FD(g/cc)2	0.22	0.5	0.5	---
FRD(g/cc)3	0.11	0.12	0.133	0.097
					MD(g/cc)4	0.22	0.22	0.22	0.22
Hardness of5	---	51	49	---
					C tear (kg/cm)	---	8.5	9.9	---
Tear separation (kg/cm)	---	1.9	2.0	---
					Rebound resilience%	---	32	36	---
TStr(kg/cm2)6	---	10.4	8.9	---
					% elongation	---	206	229	---

^1-6The same meanings as in Table 1

Examples 16 to 20

These examples illustrate the use of polyol components containing different diols to produce microcellular polyurethanes according to the present invention.

TABLE 5

Examples	16	17	18	19	20
						POLY H	70.61	0	0	0	0
POLY E	21.69	0	0	0	0
						POLY I	7.7	7.7	25.76	0	0
POLY D	0	70.61	0	2.77	0
						POLY B	0	21.69	29.63	29.63	21.69
POLY C	0	0	41.84	0	0
						POLY A	0	0	0	41.84	0
POLY J	0	0	0	25.76	7.7
						POLY F	0	0	0	0	70.61
EG	10.6	10.6	8.68	8.68	10.6
						Water (W)	1.3	1.3	1.33	1.33	1.3
CAT A	2.93	3.53	1.26	1.66	2.33
						CAT E	1.0	1.0	1.0	1.0	1.0
CAT F	0.5	0.5	0.5	0.5	0.5
						CAT B	0	0	0.4	0	0
CAT D	0	0	0.3	0.3	0
						Examples	16	17	18	19	20
SURF G	0.27	0.27	0	0	0.27
						SURF F	0.5	0.5	0	0.2	0.5
PPOL	L	M	N	N	O
						NCO∶OH	1.22	1.15	1.04	1.06	1.15
D-CO2(g/l)1	1.25	1.5	1.1	1.1	1.16
						FD(g/cc)2	0.38	0.25	0.5	0.5	0.35
FRD(g/cc)3	---	---	---	---	0.113
						MD(g/cc)4	0.22	0.22	0.22	0.22	0.22
Hardness of5	53	54	61	64	---
						C tear kg/cm	8.5	---	7.6	---	---
Tear separation kg/cm	2.3	2.1	2	2.3	---
						Cell diameter, micron	---	---	10	---	---
Rebound resilience%	24	20	23	27	---
						TStr(kg/cm2)6	13.5	---	11.7	---	---
% elongation	219		120

^1-6The same meanings as in Table 1

Examples 21 to 24

These examples illustrate the use of different prepolymers to produce the microcellular polyurethanes according to the invention.

TABLE 6

Examples	21	22	23	24
					POLY D	60.3	60.3	60.3	60.3
POLY B	18.5	18.5	18.5	18.5
					POLY I	6.6	6.6	6.6	6.6
EG	9.1	9.1	9.1	9.1
					CAT A	2.5	2.5	2.5	2.5
SURF F	0.4	0.4	0.4	0.4
					Water (W)	1.2	1.2	1.2	1.2
Ultraviolet stabilizer	1.5	1.5	1.5	1.5
					PPOL	P	Q	R	S
NCO∶OH	1.3	1.3	1.3	1.3
					D-CO2(g/l)1	1.35	1.34	1.32	1.47
FD(g/cc)2	0.34	0.34	0.32	0.31
					FRD(g/cc)3	0.12	0.123	0.113	0.102
MD(g/cc)4	0.22	0.22	0.22	0.22
					Hardness of5	51	49	50	56
C tear (kg/cm)	8.3	8.3	8.8	8.1
					Rebound resilience%	21	20	22	21
Examples	21	22	23	24
					Tear separation (kg/cm)	2.2	2.1	2.2	2.1
TStr(kg/cm2)6	16.3	17	17.5	19.2
					% elongation	251	250	228	233

^1-6The same meanings as in Table 1

Examples 25 to 29

These examples illustrate the use of a polyol component containing a polymer polyol to produce a microcellular polyurethane according to the present invention.

TABLE 7

Examples	25	26	27	28	29
						POLY A	---	---	---	38.28	37.86
POLY C	36.45	36.45	36.58	---	---
						POLY B	25.81	25.81	25.9	12.09	7.08
POLY I	22.44	22.44	22.52	33.58	32.81
						POLY D	2.41	2.41	2.42	---	---
BD	---	---	---	15.11	17.88
						EG	7.52	7.52	7.55	---	1.37
CAT A	2.2	2.2	1.1	0.34	0.43
						CAT E	---	---	---	0.02	---
CAT F	---	---	---	---	0.09
						CAT G	---	---	---	---	0.43
CAT B	0.35	0.35	0.35	0.25	---
						CAT D	0.26	0.26	0.26	---	---
SURF D	---	0.30	---	0.34	0.78
						SURF H	0.43	0.35	---	---	---
SURF I	---	---	0.43	---	---
						SURF F	---	---	0.43	---	---
Examples	25	26	27	28	29
						Water (W)	1.16	1.16	1.05	0	1.28
Ultraviolet stabilizer	1.4	1.4	1.4	---	---
						PPOL	T	T	T	U	D
NCO∶OH	1.13	1.13	1.01	1.102	1.57
						D-CO2(g/l)1	0.79	0.79	0.97	1.41	0.4
FRD(g/cc)3	0.119	0.119	---	0.287	0.14
						FD(g/cc)2	0.6	0.6	0.5	0.267	0.8
MD(g/cc)4	0.22	0.22	0.22	0.29	0.22
						Hardness of5	---	---	---	---	60

^1-6The same meanings as in Table 1

Examples 30 to 36

The following examples illustrate microcellular polyurethanes produced from polyol components that do not contain added water.

TABLE 8

Examples	30	31	32	33	34	35	36
								POLY D	61.12	61.12	61.12	61.12	61.12	61.12	61.12
POLY B	18.77	18.77	18.77	18.77	18.77	18.77	18.77
								POLY I	6.66	6.66	6.66	6.66	6.66	6.66	6.66
EG	9.18	9.18	9.18	9.18	9.18	9.18	9.18
								CAT A	2.54	2.54	2.54	2.54	2.54	2.54	2.54
SURF F	0.43	0.43	0.43	0.43	0.43	0.43	0.43
								Water (W)	0	0	0	0	0	0	0
UV7	1.30	1.30	1.30	1.30	1.30	1.30	1.30
								PPOL	T	T	T	T	T	T	T
Index of refraction	99	99	99	99	99	99	99
								NCO∶OH	1	1	1	1	1	1	1
D-CO2(g/l)1	0.1	0.96	1.27	1.37	1.43	1.51	1.57
								FD(g/cc)2	0.9	0.53	0.39	0.34	0.29	0.25	0.22
FRD(g/cc)3	---	0.293	0.263	0.255	0.245	0.241	0.222

^1-3The same meanings as in Table 1.⁷UV-UV stabilizer

Having now fully described the invention, it will be apparent to those skilled in the art that many changes and modifications can be made thereto without departing from the spirit or scope of the invention as described. The terms "a" and "an" as used in the claims mean "one or more" unless otherwise indicated. The terms "major" and "majority" mean equal to or greater than 50 weight percent, or equal to or greater than 50 mole percent, as the case may be.

Claims (61)

1. An isocyanate-reactive component for producing a low density cellular polyurethane comprising:

a) a polyol having a hydroxyl functionality of at least 1.7 and a molecular weight of from about 1000 to 12000Da,

b) a catalyst,

c) a surfactant, a water-soluble surfactant and a water-soluble surfactant,

d) optionally a cross-linking agent, which is,

e) optionally water, and

f) the dissolved carbon dioxide is then removed from the reaction mixture,

wherein (1) the dissolved carbon is present in an amount sufficient to produce an isocyanate-reactive component foam concentration of about 0.1 to 0.8 g/cc and (2) the sum of the dissolved carbon dioxide plus any carbon dioxide produced during the reaction of water with isocyanate will produce a polyurethane-forming reaction mixture having a free rise density of about 0.03 to 0.3 g/cc.

2. The isocyanate-reactive component of claim 1, wherein more than one polyol is used as component a).

3. The isocyanate-reactive component of claim2, wherein a combination of a difunctional polyol and a trifunctional polyol is used as component a).

4. The isocyanate-reactive component of claim 3, wherein the difunctional polyol is present in an amount of at least about 60 weight percent based on the total weight of the diol and triol.

5. The isocyanate-reactive component of claim 1, wherein water is present in the component.

6. The isocyanate-reactive component of claim 1, wherein the polyol has a hydroxyl functionality of from about 2 to about 4.

7. The isocyanate-reactive component of claim 1, wherein a crosslinker is present in the component.

8. The isocyanate-reactive component of claim 1, wherein the polyol has an average hydroxyl functionality of from 2.01 to 2.5 and a crosslinker is present.

9. The isocyanate-reactive component of claim 1, wherein the polyol has a molecular weight of about 1500 to about 6000.

10. The isocyanate-reactive component of claim 1, wherein the polyol is a mixture of a polyether diol and a polyether triol.

11. The isocyanate-reactive component of claim 1, wherein the polyol is a polyester polyol.

12. The isocyanate-reactive component of claim 1, wherein the polyol is a polyether polyol prepared from mixed raw materials.

13. The isocyanate-reactive component of claim 1, wherein the total amount of dissolved carbon dioxide is sufficient to produce a polyurethane-forming mixture having a foam density of from 0.2 to 0.4 g/cc.

14. The isocyanate-reactive component of claim 1 further comprising a polymer polyol.

15. The isocyanate-reactive component of claim 14, wherein the polymer polyol is present in the isocyanate-reactive component in an amount of up to 50 parts by weight of polymer polyol per 100 parts by weight of isocyanate-reactive component.

16. The isocyanate-reactive component of claim 1, comprising up to 30 weight percent, based on the total weight of the polyols, of polyols having a functionality greater than 3 and less than or equal to 8.

17. The isocyanate-reactive component of claim 1, wherein at least one polyol in the isocyanate-reactive component has an unsaturation of less than 0.020 meq/g.

18. A polyurethane prepared by reacting the isocyanate-reactive component of claim 1 with a diisocyanate or polyisocyanate.

19. A polyurethane molded article having a density of less than or equal to 0.3 g/cc which is the reaction product of an isocyanate-reactive component having a foam density of from 0.2 to 0.4 g/cc according to claim 1 and a polyisocyanate in the presence of sufficient carbon dioxide to provide a polyurethane-forming mixture having a free rise density of from about 0.03 g/cc to about 0.3 g/cc.

20. A molded microcellular polyurethane prepared by reacting the isocyanate-reactive component of claim 1 with a diisocyanate and/or polyisocyanate.

21. A shoe sole made from the microcellular polyurethane of claim 20.

22. A process for producing a microcellular polyurethane comprising reacting the isocyanate-reactive component of claim 1 with a diisocyanate and/or polyisocyanate in the presence of carbon dioxide.

23. A process according to the invention, wherein a blowing agent other than carbon dioxide is also used.

24. An isocyanate terminated prepolymer having an NCO content of 5% to 30% useful in the production of molded polyurethanes having a density of less than or equal to 0.3 grams per cubic centimeter, said prepolymer comprising the reaction product of a) with b) and c), wherein:

a) is a diisocyanate and/or a polyisocyanate;

b) is a polyol having a functionality of 1.2 to 8 and a number average molecular weight of less than 3000Da,

c) optionally a chain extender.

25. An isocyanate component having a foam density of from about 0.1 to 0.8 g/cc comprising the isocyanate-terminated prepolymer of claim 24 and carbon dioxide dissolved therein.

26. An isocyanate-terminated prepolymer that is the reaction product of a) with b) and c), wherein:

a) is a diisocyanate and/or a polyisocyanate;

b) is a polyol having a number average molecular weight of from about 1500Da to about 2500Da,

c) optionally a chain extender.

27. The isocyanate-terminated prepolymer according to claim 24, wherein the polyol has an ethylene oxide content of at most 30%.

28. The isocyanate-terminated prepolymer according to claim 24, wherein a diol chain extender is used as c).

29. The isocyanate-terminated prepolymer according to claim 24, wherein dipropylene glycol is used as a chain extender.

30. The isocyanate-terminated prepolymer according to claim 24, wherein the polyol is a mixture of one or more diols and one or more triols.

31. The isocyanate-terminated prepolymer according to claim 24, wherein the polyol has a functionality of between 1.8 and 3.

32. The isocyanate-terminated prepolymer according to claim 24, wherein the diisocyanate or polyisocyanate is a modified diisocyanate or modified polyisocyanate.

33. The isocyanate-terminated prepolymer according to claim 24 having an NCO content of 16% to 24%.

34. A method of producing a molded microcellular polyurethane comprising molding a reaction mixture comprising:

a) a polyisocyanate component comprising the prepolymer of claim 24,

b) an isocyanate-reactive component, wherein the isocyanate-reactive component,

c) any carbon dioxide required to raise the total carbon dioxide content of the reaction mixture to a free rise density of the reaction mixture of about 0.03 to 0.3 g/cc.

35. A process for producing a microcellular polyurethane comprising reacting a), b) and c), wherein:

a) is a polyisocyanate component comprising the prepolymer of claim 24,

b) is an isocyanate-reactive component and is,

c) is sufficient carbon dioxide to produce a polyurethane-forming reaction mixture having a free rise density of about 0.03 to 0.3 g/cc.

36. A process for producing a microcellular polyurethane having a density of less than 0.3 g/cc comprising reacting a), b) and c), wherein:

a) is the polyisocyanate component of claim 25,

b) is an isocyanate-reactive component and is,

c) is sufficient carbon dioxide to produce a polyurethane-forming reaction mixture having a free rise density of about 0.03 to 0.3 g/cc.

37. The method of claim 33 wherein b) is the isocyanate-reactive component of claim 1.

38. The method of claim 33 wherein b) is the isocyanate-reactive component of claim 4.

39. The method of claim 34, wherein b) is the isocyanate-reactive component of claim 1.

40. The method of claim 34, wherein b) is the isocyanate-reactive component of claim 4.

41. The method of claim 35, wherein b) is the isocyanate-reactive component of claim 1.

42. The method of claim 35, wherein b) is the isocyanate-reactive component of claim 4.

43. A microcellular polyurethane produced by the method of claim 33.

44. A microcellular polyurethane produced by the method of claim 34.

45. A microcellular polyurethane produced by the method of claim 35.

46. A microcellular polyurethane produced by the method of claim 36.

47. A microcellular polyurethane produced by the method of claim 37.

48. A microcellular polyurethane produced by the method of claim 38.

49. A microcellular polyurethane produced by the method of claim 39.

50. A microcellular polyurethane produced by the method of claim 40.

51. A microcellular polyurethane produced by the method of claim 41.

52. A shoe sole produced from the microcellular polyurethane of claim 42.

53. A shoe sole produced from the microcellular polyurethane of claim 43.

54. A shoe sole produced from the microcellular polyurethane of claim 44.

55. A shoe sole produced from the microcellular polyurethane of claim 45.

56. A shoe sole produced from the microcellular polyurethane of claim 46.

57. A shoe sole produced from the microcellular polyurethane of claim 47.

58. A shoe sole produced from the microcellular polyurethane of claim 48.

59. A shoe sole produced from the microcellular polyurethane of claim 49.

60. A shoe sole produced from the microcellular polyurethane of claim 50.

61. A shoe sole produced from the microcellular polyurethane of claim 51.