MXPA00000720A - Improved water blown polyurethane soling systems - Google Patents

Abstract

This invention relates to molded articles comprising microcellular polyurethane foams, preferably integral skin foams. These exhibit improved properties and are particularly suitable for soling systems in footwear. The present invention also relates to a process for the production of these molded articles. These molded articles comprise the reaction product of (A) an isocyanate comprising a stable, liquid MDI based prepolymer containing an allophanate-modified MDI, with (B) an isocyanate reactive component, in the presence of (C) at least one blowing agent.

Description

IMPROVED SYSTEMS FOR POLYURETHANE SOILS INSUFFLED WITH WATER BACKGROUND OF THE INVENTION This invention relates to integral foams for the skin that have better properties and to a process for the production of these foams. These foams are prepared from an isocyanate consisting of a liquid and stable DIM-based prepolymer containing an allophanate modified DIM. Diluted di-ethylacetone diisocyanates and their use in the preparation of integral foams for the skin are generally known in the art. Various types of liquid diphenylmethane diisocyanates include, for example, isocyanate prepolymers, isocyanates containing allophanate groups, isocyanates containing carbodiimide groups, isocyanates containing biuret groups, etc. These are described, for example, in U.S. Pat. 3,644,457, 4,055,548, 4,115,429, 4,118,411, 4,160,080, 4,261,852, 4,490,300, 4,738,991 and 4,866,103 and GB 994,890. Comprehensive skin foams prepared with polyurethane are also well known in the art. These 5sts are described, for example, in The Patents ^ .E.'Jü. 3,523,918, 3,726,952, 3,836,487, 3,925,527, 4,020,001, 4,024,090, 4,065,410, 4,305,991 and 5,166,183 and in CA 1,277,471. U.S. Pat. No. 3,644,457 describes stable liquid isocyanates at room temperature derived from one mole of diphenylmethane diisocyanate and 0.1 to 0.3 moles of poly-1,2-propylene ether glycol. U.S. Pat. 4,055,548 describes compositions of isocyanate liquid prepolymers obtained by reaction of polymethylene polyphenylisocyanate, containing from about 65 to 85 weight percent of methylene bis (phenyl) isocyanate, with a polyoxyethylene glycol having a molecular weight of 200 to 600 in a equivalent ratio of 0.0185 to 0.15: 1. The US Patents 4,115,429 and 4,118,411 disclose liquid and stable diphenylmethane diisocyanates at a low temperature (only -5 ° C) storage, which are produced by reaction of diphenylmethane diisocyanates having a specified content of 2,4-isomer with propylene glycol or poly-1, 2-propylene ether glycol. U.S. Pat. No. 4,261,852 discloses liquid polyisocyanate compositions consisting of (a) the reaction product of 90 to 50% by weight of a reaction product of diphenylmethane diisocyanate and a polyoxypropylene diol or triol having an equivalent hydroxyl weight of 750. to 3,000, whose reaction product has an NCO content of from 8 to 26% by weight, and (b) from about 10 to 50% by weight of a diphenylmethane diisocyanate containing from 30 to 65% by weight of diphenylmethane diisocyanate, the remainder being diphenylmethane polyphenyl-polyisocyanate. U.S. Pat. No. 4,490,300 describes stable liquid isocyanates at room temperature which are derived by reacting diphenylmethane diisocyanate with an aliphatic diol having a pendant aromatic group, for example 2-methyl-2-phenyl-1,3-propanediol or phenol-1,2. -ethanediol. U.S. Pat. No. 4,490,301 discloses liquid isocyanates stable at imbi.-nte temperature which are derived by reaction of diphenylmethane diisocyanate with onoalyl ether or trimethylolpropane.

U.S. Pat. No. 4,738,991 discloses organic polyisocyanates characterized by allophanate linkages, which are prepared by reaction of an organic polyisocyanate, including 2,4- and 4,4-methylenediphenyl diisocyanate, with a polyhydric or monohydric alcohol, in the presence of an organometallic catalyst. The catalyst is then deactivated using a compound, such as an inorganic acid, organic acid, organic chloroformate or organic acid chloride. This reference also discloses that flexible foams can be prepared from these isocyanates containing allophanate groups. All the examples are related to isocyanates containing allophanate groups based on DIT and only one of these prepares a flexible foam of high elasticity. U.S. Pat. No. 4,866,103 discloses a polyisocyanate composition for use in the production of elastomers in a MIR process. This polyisocyanate composition is the reaction product of an alcohol and / or thiol having an average functionality of about 1., 5 to about 4 and an average equivalent weight of at least 500, with at least 2 equivalents per equivalent hydroxyl and / or thiol of an organic polyisocyanate, including the 4,4 and 2,4 isomers of diphenylmethane diisocyanate. The reaction described is carried out under conditions such that at least about 20% of the initially formed urethane and / or thiouretene groups are converted into allophanate and / or thioalophonate groups. Another process for the preparation of allophanates containing isocyanates is described in British Patent 994,890, which relates to the reaction of urethane isocyanates with an excess of diisocyanate, either only by means of heat or in the presence of a catalyst, such as a metal carboxylate, a metal chelate or an amine tertiary, until the isocyanate content is reduced to that theoretically obtained when the complete reaction of the urethane groups is achieved. U.S. Pat. No. 4,160,080 describes a process for producing isocyanate groups which contain aliphatic and / or cycloaliphatically bound allophanate; In the process described, the compounds containing urethane groups react with polyisocyanates having aliphatic and / or cycloaliphatic isocyanate groups in the presence of a strong acid. The process is generally carried out at a temperature of 90 ° C to 140 ° C, for about 4 to 20 hours. Japanese Patent Application No. 1971-99176 discloses a method of preparing liquid diphenylmethane diisocyanate by reaction of diphenylmethane diisocyanate with an aliphatic monovalent alcohol. In U.S. Pat. 4,305,991 describes and prepares integral foams for the skin. These foams are prepared from a reaction mixture containing a polyisocyanate in which the isocyanate groups are aliphatic and / or cycloaliphatically bound. These polyisocyanates can contain adducts such as, for example, carbodiimide, allophanate, isocyanurate, uretdione, biuret, etc. The aliphatic isocyanates used to prepare these foams provide resistance to UV light and to decomposition by heat. U.S. Pat. No. 5,166,183 also describes integral foams for the skin. The polyisocyanate composition used therein has an NCO content of about 16 to 25% and consists of i) 10 to 10 parts by weight of an isocyanate having an NCO content of about 16 to 22%. , which is prepared by mixing methylenebis (phenyl isocyanate) and a methylenebis (phenyl isocyanate) modified with carbodiimide groups, followed by reaction with a polyester diol, to form a product. This product is then mixed with ii) from 0 to 90 parts by weight of a modified isocyanate having an NCO content of about 18 to 25%, which is prepared by reaction of methylenebis (phenyl isocyanate) with poly-1 , 2-propylene glycol ether. The presence of the carbodiimide-modified isocyanate in the prepolymer serves to reduce the freezing point. The integral foams for the foot "of US Pat. No. 5,166,183 are described as" μosee "orc.s of a better resistance to abrasion, and the use of a polyester in the formation of the prepolymer contributes. however, they add to the cost of the prepolymer and have a lower miscibility (solubility) with the polyethers, in such a way that the processing of the systems is difficult, and carbodiimide-modified isocyanates are also described as isocyanates suitable for the production of foams. US Patent Nos. 5,342,856 These isocyanates react with an isocyanate-reactive component and a solution of a zinc carboxylate in an aliphatic polyamine These solutions of zinc carboxylates in Lifetic polyamines and water are essential for the preparation of integral foams for the skin US Patent 4,477,602 describes a system for the production of polyurethanes with better resistance to fatigue by bending at low temperature and resistance before the cochuta. A key component of this system is a dispersion of a polyurea and / or a polyhydrazodicarbonamide in an organic compound. The examples also use CFC-11 as a primary insufflating agent, with water as a minor insufflating agent. U.S. Pat. 5,585,409 describes a process for producing molded polyurethanes with a cellular core and a compact surface area. It is polyurethanes which are produced from a system consisting of a semi-prepolymer isocyanate containing ester groups, which is prepared from a polyester polyol and a branched chain dihydroxy compound containing at least one bound ester unit. U.S. Pat. 5,624,966 discloses a polyurethane composition for producing polyurethane articles having a tensile strength greater than or equal to 450 psi and / or a Taber abrasion (loss mg) of less than 200. US Pat. 5,514,723 describes an improvement with respect to the process described in US Pat. 5,166,183. More concretely, patent 5,514,723 relates to the discovery that a particular combination of catalysts improves the ratio of the tensile strength of the skin to the tensile strength of the core of the integral skin foams described in Patent 5,166,183. This combination of catalysts consists of: a) a diorganotin sulfide corresponding to a specific formula, b) a tertiary amine and c) a tin compound capable of catalyzing the reaction between an isocyanate group and an active hydrogen atom, with the proviso that c) is not a diorganotin sulfide as described in a). The co-pending application of the Applicants Serial No. 08 / 680,094, filed on July 15, 1396, of common assignment, is related to integral foams for the skin. These foams are prepared from an isocyanate consisting of a liquid and stable DIM-based prepolymer containing an allophanate modified DIM. The integral skin foams of this application had a superior abrasion resistance compared to integral skin foams made with different isocyanates. These integral foams for the skin did not, however, exhibit the flexural properties required for shoe applications. Moreover, when allophanate modified isocyanates were used in formulations that were expected to result in improved flexural properties, it was found that certain isocyanate prepolymers modified with allophanate were superior to the allophanate modified isocyanatob required in this co-pending application. The better abrasion resistance described in the above copending application would actually be of little advantage in the present invention, since the systems of the present invention already achieve superior abrasion resistance by other means. On the other hand, the best bending properties of the molded articles claimed in the present application are not obvious, nor would be expected to be, when considering the copending application. An object of the present invention was to develop an integral system for pcliurethane skin especially suitable for sole or shoe soles applications. (that is, shoes). This requires that the system possess superior properties of fatigue by dynamic bending. It was preferred that these systems use an insufflating agent consisting of water. Another object was to avoid the drawbacks resulting from the use of prolonged prepolymers with polyester. Sayings Drawbacks include, for example, high viscosities, high costs and susceptibility to hydrolysis.

COMPENDIUM OF THE INVENTION This invention relates to a molded article consisting of a microcellular polyurethane foam, preferably a shoe sole, and to the production process of this molded article containing a polyurethane foam. This polyurethane product is formed by the reaction of (A) a liquid and stable DIM-based prepolymer, which contains an allophanate-modified DIM, with (B) an isocyanate-reactive composition and (C) an insufflating agent. The liquid and stable DIM-based prepolymers (A) having an NCO content of 5 to 30% contain an allophanate modified DIM and consist of the reaction product of: 1) an allophanate modified DIM prepared by reaction of i) an aliphatic alcohol or an aromatic alcohol, wherein said alcohol contains less than 17 carbon atoms, with ii) diphenylmethane diisocyanate, consisting of from about 0 to 60% by weight of 2,4,4-diiphenylmethane diisocyanate less than 6% by weight of 2,2'-diphenylmethane diisocyanate and the remainder being 4,4'-diphenylmethane diisocyanate, and 2) a polyether polyol containing from 2 to 3 hydroxyl groups, preferably 2 hydroxyl groups, and having a molecular weight of from about 750 to 10,000, preferably from about 1,000 to about 6,000, where the polyether polyol is prepared from a starting compound with ethylene oxide and propylene oxide in a weight ratio of 10:90 to 70:30, preferably 13:87 to 50:50 and, more preferably, 15:85 to 35:65 . Suitable isocyanate-reactive compositions (B) consist of; (1) from about 25 to about 92% by weight, based on the total weight of component (B), of at least one polyether polyol having a functionality of about 2 and a molecular weight of about 3,000 to about 8,000; (2) from about 5 to about 72% by weight, based on the total weight of component (B), of a filled polyol (preferably, a dispersion of a polyurea and / or a polyhydrazodicarbonamide in an organic compound containing the minus two hydroxyl groups, or an EAN graft polyol), wherein said filled polyol has a functionality of about 2.5 to 3 (preferably 3) and a molecular weight of about 3,000 to about 8,000 (preferably about 4. 800 to about 6,000), and (3) from about 3% to about 30% by weight, based on the total weight of component (b), of at least one organic compound containing 2 to 4 hydroxyl groups and having a molecular weight of from about 28 to about 250. Preferred compounds for use as a component (B) (3) are 1,4-butanediol, ethylene glycol and mixtures thereof, ethylene glycol being most preferred. The above components (A) and (B) react in the presence of (C), an insufflating agent which preferably consists of water and, optionally, (D), others additives Other additives include, for example, one or more catalysts and / or one or more surfactants. Components (A) and (B) are present in amounts such that the isocyanate index is from about 90 to 110, preferably about 96 to 103. This invention also relates to a process for the production of these molded articles consisting of in foamed micro-cellular polyurethane products.

DETAILED DESCRIPTION OF THE INVENTION Suitable liquid and stable DIM-based prepolymers, having an NCO content of about 5 to 30%, preferably 15 to 25%, more preferably 17 to 23% and, more preferably, 18 to 20%, and that contain a DIM modified with allophanate. These liquid and stable DIM-based prepolymers consist of the reaction product of: 1) an allophanate-modified DIM and 2) a polyether polyol. These isocyanate prepolymers are known and are described, for example, in US Pat. 5,319,053, the description of which is incorporated herein by reference. The modified allophanate-adapted DIM 1) for use in the preparation of the liquid and stable DIM-based prepolymer consists of the reaction product of (i) an aliphatic alcohol or an aromatic alcohol, wherein said alcohol contains less than 17 carbon atoms, preferably from about 2 to about 8 carbon atoms, and ii) diphenylmethane diisocyanate, consisting of from about 0 to 60% by weight of 2,4'-diphenylmethane diisocyanate, less than 6% by weight of diisocyanate of 2. , 2'-diphenylmethane and the remainder being diisocyanate of 4,4'- diphenylmethane. Some compounds suitable for use as aliphatic alcohols (i) include, for example, isomeric butanols, isomeric propanols, isomeric pentanols, isomeric hexanols, cyclohexanol, 2-methoxyethanol, 2-bromoethanol, etc. Suitable aromatic alcohols for use in the preparation of the allophanate-modified prepolymer include, for example, phenol, 1-naphthol, m-cresol and p-bromophenol. Preferred aliphatic alcohols are 1-butanol, 1-pentanol and 1-propanol. Preferred aromatic alcohols are phenol and m-cresol. Aliphatic alcohols are particularly preferred. The di-ethylacetate diisocyanate preferably comprises about 0 to about 6% of the 2,4'-isomer of the DIM, about 0 to about 2% of the 2,2'-isomer of the DIM and about 92 to about 100. % of the 4,4 'isomer of the DIM. It is preferred that the allophanate-modified DIM 1) is also a stable liquid and has an NCO content of about 15 to 30%. Suitable polyether polyols 2) which are to react with the allophanate 1) modified DIM to form the currently required liquid and stable DIM prepolymers A) containing an allophanate modified DIM include polyether polyols containing about 1.5 to 3 hydroxyl groups, preferably 1.8 to 3 hydroxyl groups, more preferably 2 to 3 and, more preferably, 2 hydroxyl groups and having molecular weights of from about 750 to about 10,000, more preferably from about 1,000 to about 6,000. These polyether polyols include those which have a low unsaturation, which can be prepared from, for example, a metal cyanide catalyst. double. These polyether polyols having a low content of onool can be prepared by any of the known processes, such as those described in, for example, US Pat. 5,523,386, 5,527,880, 5,536,883, 5,563,221, 5,589,431, 5,596,075 and 5,637,673, the descriptions of which are hereby incorporated by reference. These polyether polyols can be obtained in a known manner by reaction of a suitable starting compound containing reactive hydrogen atoms with ethylene oxide and propylene oxide, in a weight ratio of 10:90 to 70:30, preferably 13: 87 to 50:50 and, more preferably, 15:85 to 35:65 (ratio OE: OP). Suitable starting compounds containing reactive hydrogen atoms include, for example, polyhydric alcohols such as, for example, ethylene glycol, propylene glycol- (1, 2) and - (1,3); butylene glycol- (1, 4) and - (1,3); hexanediol- (1, 6); octanediol- (1, 8); neopentyl glycol, cyclohexanedi ethanol (1,4-bishydroxymethylcyclohexane); 2-methyl-l, 3-p;; opanediol; 2,2,4-trimethyl-1,3-pentanediol, triethylene glycol, tetraethylene glycol, polyethylene glycol; dipropylene glycol; polypropylene glycol; dibutylene glycol and polybutylene glycol; glycerin and trimethylolpropane, and, in addition, water, methanol, ethanol, 1,2,6-hexanetriol, 1,2,4-butanetriol, trimethylol-ethane, pentaerythritol, mannitol, sorbitol, methyl glycoside, sucrose, phenol, isononylphenol, resorcinol, hydroquinone and 1,1,1- or 1,1,1-tris (hydroxyphenyl) ethane. Preferred starting compounds for the polyether polyols of the present invention include, for example, propylene glycol, glycerin, water, ethylene glycol, diethylene glycol and trimethylolpropane. The preferred polyether polyols for the preparation of the stable liquid DIM based prepolymer containing allophanate groups are those compounds having a functionality of about 2, molecular weights of from about 1,000 to about 6,000 and which are prepared by alkoxylation of a suitable initiator (preferably propylene glycol) with ethylene oxide, propylene oxide or mixtures thereof in a weight ratio OE: OP of 10: 90 to 70:30, preferably 13:87 to 50:50 and, more preferably, 15:85 to 35:65. The above-described liquid DIM-based prepolymer containing allophanate groups reacts with an isocyanate-reactive composition (B) to form the polyurethane article of the present invention. Suitable isocyanate-reactive compositions consist of (1) from about 25 to about 92%, preferably from 65 to 85% by weight, based on the total weight of component (B), of at least one polyether polyol which it has a functionality of about 2 and a molecular weight of about 3,000 to about 8,000, preferably about 3,500 to 4,500; (2) from about 5 to about 72%, preferably from 5 to 25% by weight, based on the total weight of the component (B), of at least one filled polyol having a functionality of about 2 5 to about 3, preferably about 3, and a molecular weight of from about 3,000 to about S000, preferably from about 4,800 to about 6,000, and (3) from about 3 to about 30%, preferably from 3 to 15% by weight, based on the total weight of component (B), of at least one organic compound containing from about 2 to about 4 hydroxyl groups, preferably about 2 hydroxyl groups, and having a molecular weight of about 28 to about 250, preferably about 60 to 110. Polyether polyols suitable for use as component (B) (1) of the present invention include, for example, those having a functionality of about 2, preferably 2, and a molecular weight of about 3,000 to about 8,000, preferably 3,500 to 1,500. Suitable polyethers of high molecular weight for use according to the invention are known and can be obtained, for example, by polymerizing tetrahydrofuran or epoxides such as, for example, ethylene oxide, propylene oxide, butylene oxide, styrene oxide or epichlorohydrin, in the presence of suitable catalysts, such as, for example BF3 or KOH or double metal cyanides. , or by chemical addition of these epoxides, preferably ethylene oxide and propylene oxide, in admixture or successively to components containing reactive hydrogen atoms, such as water, polyols or amines. Examples of suitable polyols and amines which can be used as starting compounds for component (B) (1) include the low molecular weight diols, diamines and amino alcohols known in the art. The following are suitable examples of these types of compounds and include propylene glycol, ethylene glycol, water, bisphenol A, N, N'-dimethylethylenediamine, N-methylethanolamine, etc. It is preferred to use polyether polyols having a functionality of 2, molecular weights of about 3,000 to about 8,000 and prepared by alkoxylation of a suitable initiator with ethylene oxide and, preferably, propylene oxide, or mixtures thereof. Preferred initiator compounds include propylene glycol, water, ethylene glycol and di-inking! . It is, of course, also possible to use mixtures of diols, diamines and / or amino alcohols with a small amount of onool, triol, triamine, etc., as starting compounds for component (B) (1), provided that the mixture satisfies the above functionality requirements. Suitable compounds for use as component (B) (2) in the present invention are filled polyols. The term "filled polyol" as used herein means: (i) dispersions of polyureas and / or polyhydrazodicarbonamides in relatively high molecular weight organic compounds containing at least two hydroxyl groups, (ii) polymeric polyols prepared by polymerization of one or more ethylenically unsaturated monomers, such as styrene and acrylonitrile, in relatively high molecular weight organic compounds containing at least two hydroxyl groups and (iii) mixtures thereof. These filled polyols are known and can be characterized as hydroxyl-containing compounds containing polyadducts, polycondensates or high molecular weight polymers in finely dispersed or dissolved form. Polymer polyols suitable for the present invention are known. Methods for their manufacture are described in US Pat. 3,383,351, 3,304,273, 3,523,093, 3,652,639, 3,823,201 and 4,390,645, the descriptions of which are all incorporated herein by reference. Polyurea and / or polyhydrazodicarbon dispersions suitable for the present invention are also known and are prepared by reacting an organic polyisocyanate with polyamines containing primary and / or secondary amine groups, hydrazines, hydrazides or a mixture thereof in the presence of materials containing hydroxyl of relatively high molecular weight. These dispersions are described in U.S. Pat. 4,042,537, 4,089,835, 3,325,421, 4,092,275, 4,093,569, 4,119,613, 4,147,680, 4,184,990, 4,293,470, 4,296,213, 4. 305,857, 4,305,858, 4,310,448, 4,310,449, 4,324,716, 4,374,209, 4,496,678, 4,523,025, 4,668,734, 4,761,434 and 4,847,320, the descriptions of which are all incorporated here reference. The dispersions typically have solids contents of 1 to 40% by weight and, preferably, 10 to 30% by weight. It is preferred that the component (B) (2) contains a so-called polyol PHD (polyhydrazodicarbonamide dispersion). Suitable organic compounds for use as component (B) (3) in the isocyanate-reactive composition include, for example, those organic compounds containing from 2 to 4 (preferably 2) hydroxyl groups, amino groups and their mixtures and having molecular weights of about 28 to about 250. Suitable compounds include diols, triols, tetraols, diamines, triamines, aminoalcohols and mixtures thereof. Some examples of suitable compounds containing hydroxyl groups include glycols. such as, for example, ethylene glycol, propylene glycol, 1,2- and 1,3-propanediol, 1,3- and 1,4- and 2,3-butanediol, 1,6-hexanediol, dipropylene glycol, tripropylene glycol, diethylene glycol ( say, DEG), triethylene glycol (ie, TEG), tetraethylene glycol, tetrapropylene glycol, eptapropylene glycol, 2-methyl-1,3-propanediol, 1, 10-decanediol, neopentyl glycol, 2,2,4-trimethylpentane-1,3-diol , bis (hydroxyethyl) hydroquinone, glycerol, trimethylolpropane, etc. Preferred low molecular weight compounds include ethylene glycol, 1,4-butanediol and mixtures thereof. The most preferred is ethylene glycol. The present invention also requires at least one insufflating agent. Suitable blowing agents include, for example, water and physical insufflating agents, including, for example, low-boiling alkanes, partial or fully fluorinated hydrocarbons, etc. Suitable suitable low-boiling alkanes include compounds such as, for example, acetone, pentane, hexane, cyclopentane, etc. Some examples of partially or fully fluorinated suitable hydrocarbons include compounds such as HFC-134a (1, 1, 2-tetrafluoroethane), HFC-245fa (1, 1, 1, 3, 3-pentafluoropropane), HFC-245ca (1, 1,2,2, 3-pentafluoropropane) or HFC-236ca (1,1,1,2,3,3-hexafluoropropane). Methylene chloride is also an insufflating agent suitable for the invention now claimed. Also suitable are mixtures of these various insufflating agents It is preferred that the blowing agent contains water When water is used as the sole blowing agent, it is typically used in the present invention in amounts of between about 0.05 and 1. % by weight and, preferably, between about 0.35 and 0.7% by weight, based on the total weight of the B side of the formulation Of course, as described above, water can be used in combination with other insufflating agents The above ranges for water are reduced when mixtures of water and another blowing agent are used in the present invention For example, if a physical insufflating agent is also used, the amount of water that is to be added is between about 0.05 and 0.3% by weight (based on the total weight of side B of the formulation). It is required that mixtures of insufflating agents of this type be present in amounts that are typical of a process. conventional for the production of an integral foam for the skin. In the present invention, the insufflating agents are added in an amount necessary to produce a foam of the desired density, which is determined by the application or the final use. For example, in microcellular or integral foams for the skin and, particularly, in shoe soles, the density of the molded foam is usually from about 0.2 to about 0.6 g / cc (i.e., 20 to 35 pounds) per cubic foot). Occasionally, the densities may be up to about 1 g / cc, such as, for example, in double density shoe soles, where a higher density outsole is attached to a midsole of lower density. It is also required that one or more catalysts be present in the reaction mixture according to the present invention. Suitable catalysts include, for example, tertiary amine catalysts and organometallic catalysts. Examples of suitable organometallic catalysts include, for example, organometallic compounds of tin, lead, iron, bismuth, mercury, etc. Preferred organotin catalysts include compounds such as, for example, tin acetate, tin octoate, tin ethylhexanoate, tin oleate, tin laurate, dimethyltin dilaurate, dibutyltin oxide, dibutyltin dichloride, dimethyltin dichloride, dibutyltin diacetate, diethyltin diacetate, dimethyltin diacetate, dibutyltin dilaurate, diethyltin dilaurate, dimethyltin dilaurate, dibutyltin maleate, dimethyltin maleate, dioctyltin diacetate, dioctyltin dilaurate, ddii oxide ((2-ethylhexyl) tin, etc. Other catalysts suitable for the present invention include, for example, dialkyltin mercaptides, such as, for example, dibutyltin dimercaptide, dibutyltin diisooctylmercaptoacetate, dimercaptide dimethyltin, dibutyltin dilaurylmercaptide, dimethyltin dilaurylmercaptide, dimethyltin diisooctylmercaptoacetate, di (n-butyl) tin bis (isooctylmercaptoacetate) and di (isooctyl) tin bis (isooctylmercaptoacetate), all marketed by Witco Chemical Corp., and they are especially preferred; and dialkyltin disulfides, such as, for example, dibutyltin sulfide and dioctyltin sulfide, are also suitable catalysts. It is also possible to use a delayed action catalyst, such as pentanedione iron or a bismuth carboxylate, as described in US Pat. 4,611,044, incorporated herein by reference. Heat-activated catalysts suitable for the present invention are amine salts. These catalysts include aliphatic and aromatic tertiary amines and tertiary amine epoxide adducts. Also suitable in the present invention are ammonium quaternary ammonium salts (ie, the alkoxylated tertiary amines), as described, for example, in US Pat. 3,892,687, 4,116,879 and 4,582,861, the descriptions of which are incorporated herein by reference. Suitable heat-activated amine salts include compounds such as, for example, DABCO 8154, marketed by Air Products * a triethylenediamine blocked with formic acid and other delayed action catalysts, such as DABCO WT, also marketed by Air Products, and Polycat SA-1 and Polycat SA-102, which are both blocked versions with 1,8-diazabicyclo [5.4.0] -undecene-7 acid (ie, Polycat DBU) and are marketed by Air Products. Trialkylamines and heterocyclic amines are also suitable for the present invention. Suitable compounds include, for example, trimethylamine, triethylamine, tripropylamine, tributylamine, dimethylcyclohexylamine, dibutylcyclohexylamine, dimethylethanolamine, triethanolamine, diethylethanolamine, ethyldiethanol-aane, dimethyl isopropanolamine, triisopropanolamine, triethylenediamine, tetramethyl-1,3-butanediine, N, N, N ', N'-tetramethylethylenediamine, N, N, N ', N' -tetramethylhexanediamine-1,6, N, N, N ', N', N "-pentamethyldiethylenetriamine, bis (2-dimethylaminoethoxy) methane, N, N, N'-trimethyl-N'- (2-hydroxy-ethyl) ethyldiamine, N, N-dimethyl-N ', N' - (2-hydroxyethyl) ethylene diamine, tetramethylguanidine, N-methylpiperidine, N -ethyl-peridin, N-methylmorpholine, N-ethylmorpholine, 1,4-dimethylpiperidine, 1,2,4-trimethylpiperidine, N- (2-dimethylaminoethyl) morpholine, l-methyl-4- (2-dimethylamino) piperidine , 1,4-diazabicyclo [2.2.2] octane, 2-methyl-l, 4-diazabicyclo [2.2.2] -octane quinuclidine, 1,5-diazabicyclo [5.4.0] -5-undecene and 1, 5 diazabicyclo [4.3.0] -5-nonane. The metal compounds are usually used in amounts of from about 0.005 to about 0.5% by weight, preferably from about 0.02 to 0.4% by weight, based on the total weight of the B side of the formulation. The tertiary amine catalysts, or their salts, are advantageously employed in amounts ranging from about 0.05 to about 2% by weight, preferably from about 0.1 to about 0.5% by weight, based on 100% by weight, based on the total weight of side B of the formulation. It is preferred that the total amount of the catalysts be such that they constitute less than 3% by weight, preferably less than 2% by weight, based on the total weight of the B side of the formulation. It is also possible to be able to include various additives and / or auxiliary agents in the formulation. Some examples of suitable additives include surfactant additives, such as emulsifiers and foam stabilizers. Examples thereof include N-stearyl-N ', N'-bishydroxyethylurea, oleyl polyoxyethyleneamide, stearyldiethanolamide, isostearyldiethanolamide, polyoxyethylene glycol monooleate, an ester of pentaerythritol / adipic acid / oleic acid, a hydroxyethylimidazole derivative of oleic acid, N- stearylpropylendia ina and the sodium salts of the sulfonates of castor oil or of fatty acids. Alkali metal or ammonium salts of sulfonic acid, such as dodecylbenzenesulfonic acid or dinaphthylmethanesulfonic acid and also fatty acids, can also be used as surfactant additives. Suitable foam stabilizers include water-soluble polyether siloxanes. The structure of these compounds is generally such that a copolymer of ethylene oxide and propylene oxide is attached to a polydimethylsiloxane radical. Said foam stabilizers are described in US Pat. 2,764,565. In addition to the surfactants, other additives that may be used in the molding compositions of the present invention include known agents for internal mold release, pigments, cell regulators, flame retardants, plasticizers, dyes, fillers and reinforcing agents, as glass in the form of fibers or flakes, or carbon fibers, and antistatic agents. The molded articles of the present invention can be produced by any of conventional methods suitable for producing microcellular foams. These include, for example, open mold processes, closed mold procedures and direct bonding methods. This can be done with a high pressure and low foam forming equipment Pressure. Additional details regarding these procedures can be found in, for example, Poiyurethane Handbook, 2nd Edition, Edited by Gunter Oertel, Chapter 7, pp. 329-386, Hanser Publishers, Muhich, New York. The compositions according to the present invention can > er molded using conventional processing techniques at isocyanate rates in a range of from about 95 to 105 (preferably from 96 to 100). The term "isocyanate index" (which is also commonly referred to as the "NCO index") is defined here as the isocyanate equivalents, divided by the total equivalents of materials containing isocyanate-reactive hydrogen, multiplied by 100. As used herein, the phrase "side B" refers to the mixture containing the isocyanate-reactive compositions (B) (1), (B) (2) and (B) (3), insufflating agent (C) and any catalyst, surfactant or other additive that is pre-mixed with these components before reacting with the isocyanate component. The term "molecular weight", as used herein, refers to the number average molecular weight determined by analysis of final groups. The following examples illustrate details for the process of this invention. The invention, set forth in the foregoing description, is not limited in spirit or scope by these examples. Those skilled in the art will readily understand that known variations of the conditions of the following procedures can be used. Unless otherwise indicated, all temperatures are degrees Celsius and all parts are parts by weight.

EXAMPLES The following components were used in the working examples: Polyol A: a polyether diol having an OH number of about 28, prepared with propylene glycol, propylene oxide and ethylene oxide, the weight ratio of propylene oxide to oxide being of ethylene of 70:30, being approximately 100% of the primary OH groups. Polyol B: a dispersion having an OH number of about 28 and consisting of a polyhydrazodicarbonamide in propylene oxide / ethylene oxide polyether initiated with glycerin (having an OH number of about 35%)., the weight ratio of propylene oxide to ethylene oxide being about 5: 1). This polyol was produced by the reaction of toluene diisocyanate and hydrazine in the presence of the polyether initiated with glycerin as described in US Pat. No. 4,042,537, the description of which is hereby incorporated by reference. The resulting dispersion has a solids content of about 20% by weight. 1,4-BD: 1,4-butanediol. EG: ethylene glycol. CAT A: a 1: 3 mixture of triethylene diamine in 1,4-butanediol, marketed by Air Products as Dabco S-25. CAT B: a tertiary amine catalyst consisting of 30% amine and 70% 1,4-butanediol, marketed by Air Products as Dabco 1028. CAT C: Dibutyltin dilaurylmercaptide, commercially available Listed by Witco as UL-1. CAT D: Dibutyltin dilaurate catalyst, marketed by Air Products as T-12. CAT E: an n-alkyl-substituted organoe & catalyst, marketed as Topcat 190 by Tylo Industries, Parsippany, NJ. L5309: a copolymer surfactant of polyalkylene oxide and dimethylsiloxane marketed by OSi Specialties, Inc. ISO A: an isocyanate having an isocyanate group content of about 19% by weight and which is prepared by reaction of: (i) 56 parts by weight of the 4,4'-isomer of methylenebis (phenyl isocyanate), (ü) 6 parts by weight of a carbodiimide-modified methylenebis (phenyl isocyanate) having an isocyanate group content of "29.3% and viscosity at 25 ° C of less than 100 mPa.s and (iii) 38 parts by weight of a polyester diol of a molecular weight of 2,000 prepared by reaction of adipic acid, 1,4-butanediol and ethylene glycol, where the molar ratio of ethylene glycol a butanediol is 1: 1.

(This isocyanate is identical to the isocyanate used in the examples of US Patent 5,514,723, column 6, lines 34-46). ISO I: an allophanate modified prepolymer having an NCO content of about 18.9% by weight and a viscosity of 440 mPa.s at 25 ° C, the prepolymer being a trans-product, light yellow in color. This prepolymer was prepared by the following procedure: 100 parts by weight of DIM (98% by weight of 4,4'-DIM and 2% by weight of 2,4'-DIM) were added to a reactor padded with nitrogen. While stirring the DIM at 50 ° C, 3.2 parts by weight of 1-butanol was added. This reaction produced an exotherm at about 60 ° C. 0.008 parts by weight of zinc acetylacetonate (ZnAcAc) was added to the reaction mixture at 60 ° C. This mixture was then heated to 90 ° C and maintained for about 1.5 hours. 0.016 parts by weight of benzoyl chloride stabilizer were then added and the reaction mixture was cooled to approximately 60 ° C. This formed an Allophane modified DIM having an NCO content of about 29.0% by weight. Finally, 48.9 parts by weight of Polyol A were added to the DIM modified with allophanate while it was at 60 ° C. This mixture was maintained at 60 ° C for about 1.5 hours, followed by cooling to 25 ° C. This formed a transparent light yellow product, which was an allophanate-modified prepolar that exhibited the NCO content and viscosity indicated above. . Isocyanates B to L, all of them prepolymers of isocyanate modified with allophanate, were prepared using the same basic procedure as that described above for ISO I, with differences in relative amounts of reagents, etc. shown in TABLES 1A and IB.

TABLE IT: 1 Parts of 1-butanol and polyether are per 100 parts by weight of DIM. 2 IMA: isocyanate modified with allophanate. 3 Molecular weight of the polyether polyol used to prepare the AMI prepolymer. Propylene glycol was the initiator for the preparation of all polyethers. 4 Weight ratio of ethylene oxide (EO) to propylene oxide (PO) in the polyether used to prepare the prepolymer.

TABLE IB: 1 Parts of 1-butanol and polyether are per 100 parts by weight of DIM. 2 IMA: isocyanate modified with allophanate. 3 Molecular weight of the polyether polyol used to prepare the IMA prepolymer. Propylene glycol was the initiator for the preparation of all polyethers. 4 Weight ratio of ethylene oxide (EO) to propylene oxide (PO) in the polyether used to prepare the IMA prepolymer. The isocyanates A, E and G reacted with a polyol mixture as indicated in the following Table 2. The flexure data were obtained from hand-mixed foams worked at a ratio of 100 parts of polyol mixture to 74 parts of isocyanate (that is, an NCO index of 98). The hand-mixed foams were mixed for about 5 seconds to about, 24 ° C The examples of Tables 1 to 7 were mixed foams am.no.The mold used for the bending studies was an aluminum panel mold having internal dimensions of 6 inches by 6 inches by 5/8 inches and had a series of parallel wrinkles that started 1/2 inch from the edge of the mold and were separated from each other by 1/2 inch.Each wrinkle was 1/8 inch tall by 1/8 inch wide and ran the full width 6 inches of the mold These wrinkles in the mold resulted in panels that had grooves, which acted making the panels more susceptible to cracking under repeated bending.The panels were demolded in approximately 4 to approximately 5 minutes. bending test with a Ross bending meter using a modified method of ASTM-D-1052, where the test samples were not cut.

TABLE 2 The allophanate modified E and G prepolymers resulted in molded panels exhibiting better flexural performance, as described in the following Table 3.

TABLE 3: The tests of the examples set forth in Table 3 were performed for 130,000 cycles before stopping the test. Molded parts having dimensions of 4 inches x 5 inches x 1 inch were used in Examples 1, 2 and 3. TABLE 4: Physical properties of the Axis 1, 2 and 3.

The following ASTM methods were used to determine the physical properties in the operative examples of this application. Hardness: D-2240 Tensile Strength: D-412 Lengthening: D-412 Tear Die C: D-624 and D-3489 Bouncing Ball: D-3574 Taber Abrasion: D-3489 The examples in Tables 2, 3 and 4 clearly demonstrate that the allophanate-modified prepolymer isocyanates of the present invention form molded polyurethane (ie foams) beads, which are particularly suitable for shoe soles applications (see Example 3). ). These molded parts exhibit better resistance to flexural fatigue compared to the current state of the art, which uses an isocyanate prepolymer prolonged with polyester and modified with carbodiimide (see ISO A above), as indicated in Example 1 and according to is described in U.S. Pat. No. 5,514,723, and, as compared to the molded parts based on an allophanate-modified prepolymer isocyanate wherein the polyether used to prepare the prepolymer contains 100% OP groups. Another series of foamed panels mixed by hand was formed using the procedure described above, except for the use of different polyol formulations, as indicated in Table 5, and that the size of the mold was smaller. More specifically, the size of the mold used in this series of examples was only 3/8 of an inch thick, instead of 5/8 of an inch thick. The other aspects of the mold were identical to those described above. In addition, isocyanates A, F and J were used in these axes.

TABLE 5: The molded panels of this series of examples, which were based on allophanate modified isocyanate prepolymers also exhibited better flexural properties compared to the carbodiimide-modified isocyanate of US Pat. 5,514,723. The results of the bending tests were as indicated in Table 6. The bending tests were performed with a Ross bending meter, using a modified method of ASTM-D-1052, where the test samples were not cut.

TABLE 6: The tests of the examples set forth in Table 6 were performed for 700,000 cycles before stopping the test. This was enough to differentiate the examples.

TABLE 7: The advantages of the bending tests of the molded parts produced according to the present invention were obtained without significant losses in other physical / mechanical properties, as can be seen by comparing the test results of Example 6 versus Examples 4 and 5 of Tables 6 and 7. Another series of molded parts was produced. (See Tables 8 and 9). These were, however, machine-mixed using a Kymofoam type KF-IS-202 foam machine, at a mixing speed of approximately 3,800 rpm, at a temperature of approximately 26-33 ° C, with an output of approximately 60 g. /second. This series of molded parts used the formulations indicated in Table 8 and Table 9 which is given below summarizes the physical properties of the examples in Table 8.

This series of examples made it clear that although it is possible to achieve good physical properties in the molded parts (foams) when the isocyanite prepolymer is based on a polyether containing 100% propylene oxide (OP), regardless of whether the Foams were mixtures by hand or machine, a problem arises routinely in the dimensional stability of the foams machine mixes. Machine-mixed foams are poorly deformed or demolded, having severe shrinkage or sagging in some areas and large bumps in other areas. To put it more simply, the molded part does not conform to the shape of the mold. The reasons for this are unknown and are not clear at this time. It seems that, however, the hand mixing of formulations in which the isocyanate is a prepolymer based on a polyether containing 100% OP tends to mask the dimensional instability that occurs with machine mixing. Although hand mixing may be suitable for laboratory and / or other small-scale operations, it is not commercially acceptable and / or feasible due to the cost that would be incurred and / or the time constraints associated with manual mixing.

TABLE 8: TABLE 9: 1 mg lost / 1,000 cycles 2 The molded panel conforms to the shape of the mold. There is no visible distortion. 3 Distortions in the shape of the molded part. The edges are warped instead of straight. 4 In addition to having distortions as to the shape of the molded part and that the edges are warped instead of straight, the surface has large bulges and areas of extreme shrinkage.

The mold cavity for these examples formed a "rectangular parallelepiped", that is, the bases were rectangular (actually, square) with perpendicular faces. Thus, with respect to dimensional stability, a "good" rating means a part conforming to the shape of the mold, i.e., that it was a rectangular parallelepiped; a "poor" rating means a part that showed distortion, so that, for example, the angles between the faces were not 90 °, but the surfaces were relatively flat. A rating of "very poor" means a part that exhibits large protuberances and areas of shrinkage or subsidence, as well as the angular distortion described above. Two examples are given in Tables 10 and 11. Table 10 shows the formulations and Table 11 shows the properties. The properties were determined using the ASTM methods previously indicated, with the exception of the flexion data. The flexure data was obtained with a Ross bending meter according to ASTM-D-1052, by die cutting the test samples as required by this ASTM. The test samples for the bending tests were 6 inch x 6 inch x 1/2 inch panels. Example 15 is a comparative example and Example 16 is representative of the present invention. These foams were machine mixed as described above with respect to the formulations of Tables 8 and 9.

TABLE 10: TABLE 11: PHYSICAL PROPERTIES OF EXAMPLES 15 AND 16 g lost / 1,000 cycles Although the invention has been described in detail in the foregoing for purposes of illustration, it should be understood that said detail has only that purpose and that those skilled in the art can make variations in it without departing from the spirit and scope of the invention, except as may be limited by the claims.

Claims (15)

1. A molded article consisting of a microcellular polyurethane foam and which is the reaction product of (A) a stable prepolymer based on liquid DIM having an NCO content of 5 to 30% and containing a DIM modified with allophanate, wherein said prepolymer consists of the reaction product of (1) an allophanate-modified DIM prepared by reaction of (i) an aliphatic alcohol or an aromatic alcohol, wherein said alcohol contains less than 17 carbon atoms , with (ii) diphenylmethane diisocyanate consisting of about 0 to 60% by weight of 2,4,4'-diphenyl methane diisocyanate, less than 6% by weight of 2,2'-diphenylmethane diisocyanate and the remainder being 4,4 '-diphenylmethane diisocyanate, and (2) a polyether polyol containing 2 to 3 hydroxyl groups and having a molecular weight of about 750 to 10,000, which polyether polyol is prepared from a starting compound with ethylene oxide and propylene oxide in a weight ratio of 10:90 to 70:30, with (B) an isocyanate-reactive composition consisting of: (1) from about 25 to about 92% by weight, based on the total weight of component (B), of at least one polyether polyol having a functionality of 2 and a molecular weight of about 3,000 to about 8,000 , (2) from about 5 to about 72% by weight, based on the total weight of component (B), of a filled polyol, whose filled polyol has a functionality of about 2.5 to 3 and a molecular weight of about 3,000 to about 8,000, and (3) from about 3 to about 30% by weight, based on the total weight of component (B), of at least one organic compound containing 2 to 4 hydroxyl groups and having an molecular weight from about 28 to about 250; in the presence of (C) an insufflating agent, wherein the amounts of the components (A) and (B) are such that the isocyanate number is from about 90 to about 110.

2. The molded article of Claim 1, wherein (A) (1) said allophanate-modified DIM is prepared by reaction of (i) an aliphatic alcohol or an aromatic alcohol, wherein said alcohol contains from 2 to 8 carbon atoms, with ( ii) diphenylmethane diisocyanate consisting of about 0 to 6% by weight 2,4,4'-diphenylmethane diisocyanate, from about 0 to about 2% by weight diisocyanate of 2, 2'-diphenylmethane and the remainder being 4,4'-diphenylmethane diisocyanate.

3. The molded article of Claim 1, wherein (A) (2) said polyether polyol contains 2 hydroxyl groups, it has a molecular weight of from about 1,000 to about 6,000 and is prepared from a starting compound with ethylene oxide and propylene oxide in a weight ratio of 13:87 to 50:50.

4. The molded article of Claim 3, wherein the weight ratio of ethylene oxide to propylene oxide is from 15:85 to 35:65.

5. The molded article of Claim 1, wherein (B) (2) said filled polyol consists of a dispersion of a polyurea and / or a polyhydrazodicarbonamide in an organic compound containing at least two hydroxyl groups.

6. The molded article of Claim 1, wherein (B) (2) said filled polyol consists of an EAN graft polymer polyol.

7. The molded article of Claim 1, wherein (B) (2) said filled polyol has a functionality of about 3 and a molecular weight of about 4,800 to 6,000.

8. The molded article of Claim 1, wherein (B) (3) said organic compound is selected from the group consisting of 1,4-butanedioi, ethylene glycol and mixtures thereof.

9. The molded article of Claim 1, wherein (A) (1) said allophanate modified DIM is prepared by reacting (i) n-butanol with (ii) diphenylmethane diisocyanate consisting of about 0 to 6% in weight of 2,4 '-diphenylmethane diisocyanate, approximately 0 to 2% by weight of 2,2'-diphenylmethane diisocyanate and the remainder being 4,4'-diphenylmethane diisocyanate.

10. The molded article of Claim 1, wherein (A) said stable prepolymer based on liquid DIM has an NCO content of 14 to 20% -.

11. The molded article of Claim 9, wherein (A) (1) said allophanate modified DIM has an NCO content of 23 to 30%.

12. The molded article of Claim 11, wherein (A) (1) said allophanate modified DIM has an NCO content of about 29%.

13. The molded article of Claim 1, wherein (A) (2) said polyether polyol has a functionality of 2, a molecular weight of 4,000 and is prepared from ethylene oxide and propylene oxide in a weight ratio of 20:80 to 30:70.

14. The molded article of Claim 1, wherein (C) said insufflating agent consists of water.

15. The molded article of Claim 1, wherein said reaction is in the presence of (D) additives consisting of one or more catalysts and / or one or more surfactants.