MXPA06005320A

MXPA06005320A - Stable liquid, allophanate-modified diphenylmethane diisocyanate trimers, prepolymers thereof, and processes for their preparation

Info

Publication number: MXPA06005320A
Application number: MXPA/A/2006/005320A
Authority: MX
Inventors: E Slack William
Original assignee: E Slack William
Priority date: 2003-11-12
Filing date: 2006-05-11
Publication date: 2006-10-17

Abstract

The present invention relates to stable liquid, allophanate-modified, partially trimerized diphenylmethane diisocyanates, the prepolymers of these stable liquid, allophanate-modified, partially trimerized MDI's, and to processes for the preparation of these compositions. These allophanate modified partially trimerized diphenylmethane diisocyanates comprise the reaction product of a diphenylmethane diisocyanate and an organic compound in the presence of a catalytic amount of one or more trimer catalysts, one or more allophanate catalysts, one or more allophanate-trimer catalysts and mixtures thereof. The prepolymers are the reaction product of the stable liquid, allophanate-modified, partially trimerized MDI's with a suitable isocyanate-reactive group containing compound.

Description

DIPHENYLMETHANE DIISOCYANATE TRIMMERS MODIFIED WITH ALOFANATE, LIQUID, STABLE, PREPOLYMERS OF THE SAME AND PROCESSES FOR PREPARATION BACKGROUND OF THE INVENTION The present invention relates to stable, liquid, stable allophanate modified diphenylmethane diisocyanate dimers, to processes for their preparation, to liquid, stable, stable prepolymers of these diphenylmethane diisocyanates modified with allophanate and to a process for the preparation of the prepolymers. Trimerization of aromatic isocyanates to form polyisocyanurates is well known in the art in U.S. Patent Nos. 4,473,627 and 4,382,125 which both describe the partial trimerization of polymethylene polyphenylene polyisocyanate (p-MDI) having average functionality of > 2.2, to give stable liquid products having a relatively high viscosity at 25 ° C (ie, 2000-100,000 mPa.s). U.S. Patent No. 4,284,730 refers to the trimerization of monomeric MDI that has been partially converted to carbodiimide / uretonimine, to give stable liquid polyisocyanurate compositions. U.S. Patent No. 5,124,370 discloses liquid polyisocyanate mixtures containing isocyanurate groups having an NCO content of 15 to 30% by weight. These mixtures are obtained by the partial trimerization of the isocyanate groups of polyisocyanate mixtures of the diphenylmethane series containing from 80 to 100% by weight isomers of diphenylmethane diisocyanate and from 0 to 20% by weight of higher-ring compounds of the diphenylmethane series, wherein the monomer is composed of 20 to 60% by weight of 2,4'-diphenylmethane diisocyanate, 0 to 8% by weight of 2,2'-diphenylmethane diisocyanate and 40 to 80% by weight of 4,4'-diphenylmethane diisocyanate. Trimerization of toluene diisocyanate in a solvent to prepare a stable liquid during storage is described in both U.S. Patents 4,379,905 and DE 19,523,657. These products are described as suitable as isocyanate components in two component polyurethane lacquers. U.S. Patent No. 4,456,709 discloses stable liquid polyisocyanates during storage having an NCO group content of 36.5 to 45%. These are prepared by mixing 25 to 70 parts of 2,4-TDI partially trussed with 75 to 30 parts of 2,4- and / or 2,6-TDI unmodified. U.S. Patent No. 5,905,151 relates to trimeric catalyst systems for aliphatic and aromatic isocyanates. The trimeric catalyst systems of this prior application comprise (A) a lithium compound selected from the group consisting of: (i) lithium salts of aliphatic or aromatic monocarboxylic or dicarboxylic acids, (ii) lithium salts of compounds containing the group hydroxyl having 1 to 3 hydroxyl groups per compound, wherein the hydroxyl groups are attached directly to an aromatic ring and (iii) lithium hydroxide; and (B) an organic compound containing at least one hydroxyl group. These trimeric catalyst systems result in partially trimerized isocyanates which may additionally contain a significant amount of urethane groups. According to the disclosures of U.S. Patent No. 4,379,905 and DE 19,523,657 it is necessary that the solvent be present to form the liquid products. Due to the large amount of solvent present, these products have restricted uses. In particular, these products are clearly designed to be used only in coating applications. U.S. Patent No. 4,456,709 requires pure 2,4-toluene diisocyanate in the first step. The process of this reference results in final products having a fairly small NCO content and a restricted distribution of oligomers due to the fact that the trimerization must be completed in the first stage of the process. Another trimeric catalyst system is described in U.S. Patent Nos. 5,955,608 and 6,127,308. This trimeric catalyst system is also suitable for both aliphatic and aromatic isocyanates. This system comprises (A) one or more compounds selected from the group consisting of (i) lithium salts of carboxylic acids, aliphatic or aromatic, (ií) lithium salts of compounds containing the hydroxyl group, where the hydroxyl group is attached to an aromatic ring and (iii) lithium hydroxide; (B) an allophanate catalyst and (C) an organic compound containing at least one hydroxyl group. The partially trimerized isocyanates may also contain allophanate groups and / or urethane groups.

U.S. Patent Nos. 6,028,158 and 6,063,891 describe toluene diisocyanurates modified with stable allophanate during freezing having an NCO group content of about 15 to about 42%. These compositions stable during freezing are prepared by reacting A) toluene diisocyanate, and B) an organic compound containing at least one hydroxyl group in the presence of a catalytic amount of C) at least one allophanate trimeric catalyst, or a catalytic system allophanate trimeric. These compositions contain both isocyanurate groups and allophanate groups. Also, this patent describes mixtures of these toluene diisocyanurates modified with allophanate with polyethylene poly (phenylisocyanates) (ie, PMDI), wherein the mixture has an NCO content of about 16.8 to about 41.6%; and urethane prepolymers of these toluene diisocyanurates modified with allophanate, as well as mixtures thereof with PMDI, having NCO group contents of about 14 to about 40%. U.S. Patent No. 4,518,761 discloses a process for the preparation of mixed trimers, at least partially trimerizing isocyanate two-component isocyanate groups with different reactivities (with respect to trimerization in the presence of a trimerization catalyst and mixtures of trimers prepared by this process The process comprises (a) adding a less reactive isocyanate component to a container, (b) trimerizing at least about 0.1% of the isocyanate groups of the less reactive isocyanate component in the presence of a trimerization catalyst. , (c) introducing the most reactive isocyanate component into the reaction vessel and, optionally, (d) terminating the trimerization reaction to the desired degree of trimerization by thermal decomposition of the trimeric catalyst and / or adding a stop / poison element for the catalyst.This process requires that the two isocyanate components have dif Different reactivities. Therefore, an isocyanate can have isocyanate groups attached aliphatically and / or cycloaliphatically and the other isocyanate can have aromatically bound isocyanate groups; or an isocyanate may have isocyanate groups attached aliphatically or cycloaliphatically and the other isocyanate may have isocyanate groups attached heteroaromatically, etc. This approach allows the incorporation of an aromatic isocyanate to a trimeric product that can be liquid. U.S. Patent No. 4,518,761 does not disclose or suggest how to prepare liquid trimeric products from aromatic isocyanate components. U.S. Patent No. 4,772,639 relates to a process for the production of molded polyurethane and also discloses polyisocyanate mixtures containing trimeric groups. These isocyanates are any of (1) mixtures of (i) isophorone diisocyanate and (ii) a polyisocyanate containing isocyanurate groups based on 1,6-diisocyanatohexane; or (2) mixtures of (i) isophorone diisocyanate and (ii) a polyisocyanate containing groups 'diisocyanate based on 1,6-diisocyanatohexane and isophorone diisocyanate.

U.S. Patent No. 5,798,431 describes a process for the production of polyisocyanates containing isocyanurate groups by catalytic trimerization of a mixture of a) a low molecular weight isocyanate component having aliphatically-bound isocyanate groups, an average molecular weight from 128 to 800 and an average NCO functionality of 1.7 to 2.2, and b) a low molecular weight isocyanate component having an aromatically bound isocyanate group, an average molecular weight of 148 to 800 and an average NCO functionality of 1. , 7 to 2.2, in the presence of c) an aminosilyl compound. Any excess of distillable isocyanate is subsequently removed to form a polyisocyanate having a monomer content of less than 0., 7%, based on the weight of the polyisocyanate solids. The examples refer to toluene diisocyanate and hexane ethylene diisocyanate. A process for the preparation of polyurea resin is described in U.S. Patent No. 5,319,058. It comprises (A) mixing (a) an aromatic polyamine component comprising a combination of at least two aromatic polyamine compounds corresponding to specific formulas and (b) an aliphatic polyisocyanate to form a mixture, and (B) heating the mixture to carry out the reaction between the amino groups and the isocyanate groups. Suitable polyisocyanates for component (b) comprise (bl) an aliphatic diisocyanate and (b2) a cyclic trimer of an aliphatic polyisocyanate. U.S. Patent No. 5,102,918 discloses a process for producing a modified organic polyisocyanate having an isocyanurate ring. This process comprises adding a trimerization catalyst, an organic phosphite ester and a surfactant (and optionally a ferrocene compound) to an organic polyisocyanate and / or a partially urethanized organic polyisocyanate to form isocyanurate groups of no more than 20% of the total isocyanate groups . A stop element is added, if necessary. Suitable organic polyisocyanates include both TDI and MDI. Example 18 uses MDI and TDI. U.S. Patent No. 4,255,659 discloses that isocyanates of different reactivities are suitable for the process described in that document (see column 2, lines 16-23). These include mixtures of TDI and IPDI and appear to be similar to the 761 patent discussed above. The polyisocyanates containing carbodiimide and / or uretonimine-isocyanurate are described in the United States No. 4,284,730. These can be prepared by (a) partial trimerization of a mixture of a polyisocyanate and a polyisocyanate-uretonimine with trimeric catalysts at the desired free isocyanate level, (b) sequential partial carbodiimidation to uretoni ina followed by partial trimerization of a polyisocyanate, (c) sequential trimerization of the polyisocyanate followed by partial carbodiimidation, (d) simultaneous conversion using a mixed carbodiimide catalyst system and isocyanurate catalysts, (e) mixture of liquid polyisocyanate with a polyisocyanate uretonimine mixture and a polyisocyanate isocyanurate mixture (see column 2, lines 37-50) . U.S. Patent Nos. 4,326,043, 4,359,541 and 4,359,550 each disclose dispersible polyisocyanurate polymers. Suitable isocyanates are widely described, including mixtures of TDI, MDI and PMDI. That reference also discloses that the isocyanate can be converted to a trimer in a solvent which is a solid and then dispersed in a polyol. Examples 48-84 of the 043 patent describe catalysts containing the dispersed solid trimer, surfactants, etc., are reacted with the TDI / DI isocyanate mixture (80:20) to form a foam. The stable solutions of isocyanate prepolymers trimerized in monomeric polyisocyanates are described in the '4552 patent. First, an isocyanate-terminated prepolymer is prepared, then a cotrimer is formed by trimerizing the NCO-terminated prepolymer with MDI or PMDI. The cotrimer is reacted with an excess of a low weight equivalent polyol to form another isocyanate-terminated prepolymer. TDI is suitable for forming the first NCO-terminated prepolymer. All examples use TDI and MDI and various polyols to form the prepolymers. It is expressly stated in column 5 line 50-55 that the diols must be present for the products to be liquid. Also, the first step of preparing a prepolymer followed by the addition of the second isocyanate, then trimerizing the mixture will result in the formation of allophanate. GB 1,337,659 discloses a polyisocyanate solution comprising a solution of at least one polyisocyanate containing at least one isocyanuric acid ring dissolved in a monomeric polyisocyanate which is free of isocyanurate groups. These are not mixed trimers but a TDI trimer mixed with a TDI prepolymer. Only Example 5 describes the preparation of a mixed trimeric product from MDI and TDI with 1,2-propylene glycol. However, this product contains less than 3% by weight of the trimer and there is no evidence that it is a stable liquid product. In none of the final isocyanate products of these working examples are pure mixed trimers. In stead of, each of these products contains some of a urethane and / or allophanate group and contains a relatively small amount of trimeric groups. Modifications with allophanate tend to form straight products. Therefore, it would be expected that these products were liquid. The advantages of the stable stable allophanate-modified diphenylmethane diisocyanate trimers during storage claimed in the present invention include the presence of a reduced amount of the 2,4 'isomer of diphenylmethane diisocyanate which improves the reactivity, curing and physical properties of the products. of resulting polyurethane prepared with these stable trimers. SUMMARY OF THE INVENTION This invention relates to stable, liquid modified, partially modified allophanate diphenylmethane diisocyanates having an NCO group content of about 15 to 30% by weight, preferably 20 to 28% by weight. These are the reaction products of: a) (1) a diphenylmethane diisocyanate component having (i) from 10 to 40%, preferably from 20 to 35% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6%, preferably from 0 to 2% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 54 to 90%, preferably from 63 to 80% by weight of 4,4'-diisocyanate. diphenylmethane, where the percentages by weight of a) (1) (i), a) (1) (ii) and a) (1) (iii) make a total of 100% by weight of a) (1); and b) an organic compound containing at least one hydroxyl group in the presence of a catalytic amount of: c) at least one catalyst selected from a group consisting of (1) one or more trimeric catalysts, (2) one or more allophanate catalysts , (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof. There are from about 0.01 to about 0.25 equivalents of hydroxyl groups of component b) present per equivalent of MDI isocyanate present and at least about 50% of the urethane groups are converted to allophanate groups by c) the catalyst. Preferably there are from about 0.01 to about 0.20 equivalents of hydroxyl groups per isocyanate equivalent of at least about 70% more preferably of at least about 80%, more preferably still at least about 90% and more particularly preferably at least about 95% of urethane groups are converted to allophanate groups. A catalyst stopping element is added once the desired NCO group content is obtained. The present invention also relates to a process for preparing these stable, liquid, partially-trimethylated diphenoate diisocyanates modified with allophanate. In this process, the product is prepared by (I) heating a) (1) the diphenylmethane diisocyanate containing (i) from 10 to 40%, preferably from 20 to 35% by weight of 2,4'-diphenylmethane diisocyanate , (ii) from 0 to 6%, preferably from 0 to 2% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 54 to 90%, preferably from 63 to 80% by weight of 4-diisocyanate. , 4 '-diphenylmethane, where the percentages by weight of a) (1) (i), a) (1) (ii) and a) (1) (iii) make a total of 100% by weight of a) (1) ); and b) an organic compound containing at least one hydroxyl group, at a temperature of from about 70 to about 120 ° C, preferably from 85 to 95 ° C, for a period of from about 1 to about 6 hours in the presence of a catalytic amount of c) at least one catalyst selected from the group consisting of: (1) one or more trimeric catalysts, (2) one or more allophanate catalysts, (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof . The amount of b) is such that there are from about 0.01 to 0.25 equivalents of hydroxyl group per isocyanate equivalent in a), and at least about 50% of the urethane groups are converted to allophanate groups by the catalysts. Preferably there are from about 0.01 to about 0.20 equivalents of hydroxyl groups per equivalent of isocyanate and at least about 70%, more preferably at least about 80%, more preferably still at least about 90% and more particularly preferably at least about 95% of urethane groups are converted to allophanate groups. Heating is followed by (2) adding a catalyst stop element once the desired NCO group content is reached to neutralize the catalyst in the reaction mixture. The stable, liquid-buffered, modified, allophanate-modified diphenylmethane diisocyanates having an NCO group content of 15 to 30% by weight, preferably 20 to 28% by weight, can also be a mixture of: (A) from 20 to 30% by weight. 65% by weight, based on 100% by weight of (A) and (B), of an allophanate-modified diphenylmethane isocyanate having an NCO group content of from about 16 to about 29%, and is the product of reaction of: a) (2) a diphenylmethane diisocyanate having: (i) from 0 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of diisocyanate of 2 , 2'-diphenylmethane, and (iii) from 34 to 100% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (2) (i), a) (2) (ii) ya) (2) (iii) make a total of 100% by weight of a) (2), and b) an organic compound containing at least one hydroxyl group, in the presence of: c) at least one allophanate catalyst, wherein component b) is present in an amount such that there is from about 0.05 to about 0.25. equivalents of hydroxyl groups per equivalent of MDI isocyanate present, at least about 50% of the urethane groups is converted to allophanate groups by c) and a catalyst stop element is added once the desired NCO group content of the MDI is reached modified with allophanate; and (B) from 35 to 80% by weight, based on 100% by weight of (A) and (B), of at least one partially trimerized diphenylmethane diisocyanate having an NCO group content of from about 20 to about 30. , and is the trimerization product of: (a) (3) a diphenylmethane diisocyanate having: (i) from 10 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight weight of 2,2'-diphenylmethane diisocyanate, and (iii) 34 to 90% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (3) (i), a) ( 3) (ii) and a) (3) (iii) make a total of 100% by weight of a) (3), in the presence of b) at least one catalyst selected from the group consisting of: (1) at least one trimeric catalyst, (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof, wherein the trimeric content is at least about 10 to about 80% by weight based on 100% by weight of the component ( B). The process for preparing these liquid, stable, stable, partially trimerized modified diphenylmethane diisocyanates having an NCO group content of 15 to 30%, is prepared by: (1) mixing (A) an allophanate modified diphenylmethane diisocyanate having an NCO group content of about 16 to about 29% and that is the reaction product of a) (2) MDI and b) an organic compound containing at least one hydroxyl group in the presence of c) (2) one or more allophanate catalysts where a catalyst stop element has been added once the desired NCO group content of the allophanate-modified diphenylmethane diisocyanate has been reached; with (B) at least one partially trimerized diphenylmethane diisocyanate having an NCO group content of from about 20 to about 31% and which is the trimerization product of a) (3) of MDI formed in the presence of c) ( 1) a trimeric catalyst, c) (3) an allophanate-trimeric catalyst system or mixtures thereof, wherein a catalyst stop element has been added once the desired NCO group content of the trimeric product has been reached; and (2) cooling the mixture to room temperature. The distribution of isomers for MDI a) (2) which is used in the preparation of allophanate modified MDI differs slightly from the isomer distribution indicated for MDI a) (1). The distribution of isomers for MDI a) (3) which is used in the preparation of trimerized MDI differs slightly from the distribution of isomers indicated above for MDI a) (1) in the distribution of isomers for MDI a) (2). Another aspect of the present invention relates to prepolymers of partially trimerized diphenylmethane diisocyanates modified with allophanate. These prepolymers are also stable liquids during storage as defiherein. These prepolymers have NCO group contents of from about 8 to about 28%, and comprise the reaction product of partially trimerized diphenylmethane diisocyanates modified with allophanate having an NCO group content of 15 to 30% by weight, with one component isocyanate reagent containing from about 1.5 to about 6 hydroxyl groups having a molecular weight of from about 76 to about 10,000. The partially trimerized diphenylmethane diisocyanates modified with allophanate can be prepared simultaneously, the allophanate can be prepared first and then the trimer, or the allophanate and trimer can be prepared separately and mixed together. The process of preparing urethane prepolymers of the partially trimerized modified diphenylmethane diisocyanates with allophanate comprises reacting liquid-stable, modified, allophanate-modified, partially-trimerized diphenylmethane during storage with a suitable isocyanate-reactive component as described above. As in the above case, the partially trimerized diphenylmethane diisocyanates modified with allophanate used herein may be prepared in any suitable manner. DETAILED DESCRIPTION OF THE INVENTION According to the present invention the term "liquid" means that the partially trimerized allophanate-modified product does not precipitate solids when stored at 25 ° C for 3 months.; and the term "stable during storage" means that the product modified with partially trimerized allophanate has up to 1% absolute change in percentage of NCO group content and up to 10% change in viscosity when stored at 25 °. C for 3 months. In the stable, liquid, allophanate-modified, partially-trimethylated diphenylmethane diisocyanates of the present invention and the process or processes for their preparation, the following components are generally suitable. Suitable diphenylmethane diisocyanates for use as component a) in the partially trimerized allophanate-modified diisocyanates of the present invention include those diphenylmethane diisocyanates having NCO group contents of from about 33.0% to about 33.6%, preferably from about 33.4% to about 33.6% and more preferably still about 33.6%. Suitable diphenylmethane diisocyanates a) (1) comprise (i) from 10 to 40% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate and (iii) from 54 to 90% by weight of 4,4'-diphenylmethane diisocyanate, with the percentages by weight of a) (1) (i), a) (1) (ii) and a) (1) ( iii) making a total of 100% by weight of a) (1). The weight percentage of a) (1) (i) the 2,4 'isomer of diphenylmethane diisocyanate is typically at least about 10%, and preferably at least about 20%. The percentages by weight of (i) the 2,4'-isomer is generally about 40% or less and preferably about 35% or less. The diphenylmethane diisocyanate component a) (1) can have (i) a 2,4'-isomer content varying between any of these higher and lower values including for example 10 to 40% and preferably 20 to 35%. The weight percentage of (ii) the 2,2 'isomer of diphenylmethane diisocyanate is typically about 0% or more. The weight percentage of (ii) the 2,2'-isomer is generally about 6% or less and preferably about 2% or less. The diphenylmethane diisocyanate, component a) (1), can have (ii) a 2,2'-isomer content varying between any of these higher and lower values including for example from about 0 to about 6% and preferably from about 0 to about 2%. The weight percentage of (iii), the 4,4 'isomer of diphenylmethane diisocyanate is typically at least about 54% and preferably at least about 63%. The weight percentage of (iii), the 4,4 'isomer, is generally about 90% or less and preferably about 80% or less. The diisocyanate component of diphenylmethane a) (1) may have (iii) a 4,4 'isomer content which varies between any of these higher and lower values including for example from 54 to 90% and preferably from 63 to 80%. The amounts of (i), (ii) and (iii) always make a total of 100% by weight of a) (1) diphenylmethane diisocyanate. Some examples of preferred isocyanates include isomeric mixtures of diphenylmethane diisocyanate a) (1) containing from about 20 to 35% of the 2,4'-isomer, from about 0 to about 2% of the 2,2'-isomer and from about 63 to about 80% of the 4,4 'isomer (the percentages by weight of the isomers being a total of 100% by weight) Organic compounds containing at least one hydroxyl group b) are necessary according to the claimed invention currently. Suitable compounds typically include those compounds having a molecular weight (number average) of about at least 32, preferably at least about 60 and more preferably at least about 74. These organic compounds containing at least one hydroxyl group typically also have a number average molecular weight of about 6000 or less, preferably of about 4800 or less, more preferably of about 3000 or less and more preferably still of about 1000 or less. The organic compound may have a molecular weight (number average) which varies between any combination of these upper and lower values inclusive, for example from about 32 to about 6000, preferably from about 60 to 4,800, more preferably about 74 to about 3000 and more preferably still from about 74 to about 1,000. Compounds suitable for component b) of the present invention typically also include those compounds that contain at least about one hydroxyl group. These organic compounds also typically contain about 4 hydroxyl groups or less, preferably about 3 hydroxyl groups or less, and more preferably still about 2 hydroxyl groups or less. The organic compound may contain any number of hydroxyl groups ranging from any combination of these upper and lower values including for example from about 1 to about 4, preferably from about 1 to about 3 and more preferably from about 1 to about 2. Preferred that these organic compounds containing at least one hydroxyl group are low molecular weight organic compounds containing from 1 to 4, more preferably from 1 to 3 hydroxyl groups and more preferably from 1 to 2 hydroxyl groups, and having a molecular weight in the range from 32 to about 400. Organic compounds include for example methanol, ethanol, 1,2-ethanol, 1-propanol, 2-propanol, 1-butanol, isobutyl alcohol, 2-butanol, n-amyl alcohol, alcohol sec-amyl, tere-amyl alcohol, 1-ethyl-1-propanol, n-hexanol and isomers thereof, n-octyl alcohol, 2-octyl alcohol, 2-ethyl-1-hexan ol, n-decyl alcohol, n-dodecyl alcohol, neopentyl glycol, n-tetradecyl alcohol, n-hexadecyl alcohol, n-octadecyl alcohol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2, 3 -butanediol, 3-methyl-2-butanol, 3, 3-dimethyl-l-butanol, 2-ethyl-l, 3-hexanediol, glycerol, 1,2-butanetriol, pentaerythritol, diethylene glycol, dipropylene glycol, diethylene glycol, triethylene glycol, etc. It is even more preferred for these organic compounds containing 1 to 2 hydroxyl groups such as a monoalcohol or a diol, and having a molecular weight of about 60 to about 200. Examples include 1-propanol, 2-propanol, 1- butanol, 2-butanol, n-amyl alcohol, 1-methylbutyl alcohol, 1-ethyl-l-propanol, n-octyl alcohol, 2-octyl alcohol, 2-ethyl-l-hexanol, neopentyl-glycol, 1 / 2- propanediol, 1,3-propanediol, 1,4-butanediol, 1,3-butanediol, 2,3-butanediol, 2-ethyl-1, 3-hexanediol, diethylene glycol, triethylene glycol, dipropylene glycol, tripropylene glycol, etc. Preferred compounds are isomeric alcohols having between 2 and 16 carbon atoms such as, for example, isomeric butanols and isomeric propanoles. Most preferred are 2-propanol and isobutyl alcohol.

In addition to the low molecular weight organic compounds containing at least one hydroxyl group identified above, the higher molecular weight adducts of these low molecular weight compounds are also suitable for use as component b) of the present invention. These relatively high molecular weight polyether polyols include those conventionally used in polyurethane chemistry and can be prepared by epoxidation of a low molecular weight organic compound in the presence of a suitable catalyst to produce a higher molecular weight adduct. Suitable polyether polyols typically have molecular weights in the range of greater than 400 to about 6,000, preferably from about 500 to about 3,000, more preferably from about 500 to about 2,000. It is preferred that these polyether polyols have a functionality of 1 to 3. Suitable polyethers are known and can be prepared, for example by the polymerization of epoxides optionally in the presence of a catalyst such as BF3, or by the chemical addition of said epoxides optionally as mixtures or successively, to starting components containing reactive hydrogen atoms. Suitable epoxides include ethylene oxide, propylene oxide, butylene oxide, tetrahydrofuran, styrene oxide, or epichlorohydrin. Suitable starting components include water, alcohols or amines, including for example ethylene glycol, 1,2- or 1,3-propanediol 1,2-, 1,3-, or 1,4-butanediol, trimethylolpropane, 4,4 ' -dihydroxyphenyl propane, aniline, glycerin, ammonia and ethanolamine. Polyethers containing predominantly primary hydroxyl groups (up to about 90% by weight, based on all hydroxyl groups in the polyether) are often also preferred. Also suitable are polybutadienes containing hydroxyl groups and polyalkylene polyethers such as polyoxyethylene diol, polyoxypropylene diol, polyoxybutylene diol and polytetramethylene diol. Of course, it is also possible to use a mixture of one or more of the relatively high molecular weight organic compounds containing at least one hydroxyl group, with one or more of the relatively low molecular weight organic compounds containing at least one hydroxyl group .

According to the present invention, b) the organic compound containing at least one hydroxyl group is typically present in an amount such that there is from about 0.01 to about 0.25 equivalents of hydroxyl group per equivalent of diphenylmethane diisocyanate to ) (1) present. It is preferred that there be from about 0.01 to about 0.02, more preferably about 0.03 to about 0.18, more preferably from about 0.05 to about 0.15 and more particularly preferably from about 0.07 to about 0.12 equivalents of hydroxyl groups per equivalent of diphenylmethane diisocyanate a) (1) present. There should also be at least about 50%, preferably at least about 70%, more preferably at least about 80% of the equivalents of hydroxyl groups present in b) the organic compound containing hydroxyl groups which are converted from urethane groups to groups allophanate in the final product. More preferably, at least about 90% (more particularly preferably 95%) of the eguivalents of hydroxyl groups present in b), the organic compound containing hydroxyl groups is converted to urethane groups to allophanate groups. In accordance with the present invention, a catalyst is needed to form. At least partially diphenylmethane diisocyanates trimethylated modified with allophanate, liquid, stable. Catalysts suitable for use as components in accordance with the present invention are selected from the group consisting of (1) one or more trimeric catalysts, (2) one or more allophanate catalysts, (3) a tricarbonic allophanate catalyst system and (4) ) mixtures thereof. Typically, depending on the specific catalyst or catalysts used, the present invention requires a combination of one or more trimeric catalysts and one or more allophanate catalysts.; one or more trimeric catalysts with the proviso that at least one trimeric catalyst is present to act or function to promote both trimer formation and allophanate formation (i.e. one or more allophanate trimeric catalysts) or an allophanate-trimeric catalyst system ). This is described below in more detail for convenience, although this detail is not intended to be limiting. In general, the amount of catalyst used is such that there are from about 100 to about 500 ppm of trimeric catalyst and / or trimeric allophanate catalyst present and from about 24 to about 200 ppm of allophanate catalyst present. The weight of the catalyst present is based on the total combined weight of components a) (1) and b). Suitable trimeric catalysts for use as component (1) in the catalysts of the present invention include, for example, any of the known trimerization catalysts which convert at least about 50%, preferably at least about 70%, more preferably less about 80%, more preferably at least about 90% and more particularly preferably at least about 95% of the equivalents of the urethane groups formed to allophanate groups. Some examples of trimeric catalysts include alkali carboxylates as described in U.S. Patent No. 4,604,418, the disclosure of which is incorporated herein by reference; basic alkali metal salts are complexed with acyclic organic compounds as described in U.S. Patent No. 4,379,905, the disclosure of which is incorporated herein by reference; the basic alkali metal salts are complexed with crown ethers as described in U.S. Patent No. 4,487,928, the disclosure of which is incorporated herein by reference; combinations of tertiary amines with specific quaternary ammonium salts as described in U.S. Patent No. 3,954,684, the disclosure of which is incorporated herein by reference; and alkali metal salts or quaternary ammonium salts of carboxylic acids corresponding to one or more different structures as described in U.S. Patent Nos. 4,632,785 and 4,540,781, the disclosures of which are incorporated herein by reference; various lithium salts of monocarboxylic acids, lithium salts of compounds containing the hydroxyl group and lithium hydroxide, in combination with an organic compound having at least one hydroxyl group as described for example in U.S. Patent No. 5,905 .151; etc. Other known trimeric catalysts include for example the catalyst which inherently forms both trimeric groups and allophanate groups. These trimeric catalysts include Mannich bases such as, for example, 2,4,6-bis (dimethyl-aminomethyl) phenol and metal salts of carboxylic acids such as, for example, lead octanoate and potassium acetate. In general, the best-known trimeric catalysts also result in the formation of allophanate. Therefore, depending on the embodiment of the present invention, it may be sufficient to select a trimeric catalyst to promote the formation of both trimeric and allophanate groups. A trimeric catalyst alone can be sufficient for all aspects of the present invention, except when allophanate and trimer are prepared separately and mixed together. In this particular aspect of the present invention, an allophanate catalyst is necessary to promote the formation of allophanate-modified dimethylmethane diisocyanate. Some examples of allophanate catalysts suitable for use as component (2) in the catalysts of the present invention include for example metal carboxylates and metal acetylacetonates. Some examples of allophanate catalysts suitable for the present invention include zinc octoate, Tin 2-ethylhexanoate, zinc acetylacetonate, zinc 2-ethylhexanoate, cobalt lnoresinate, lead naphthenate, lead 2-ethylhexanoate, lead linoresinate, cobalt 2-ethylhexanoate, cobalt naphthenate, etc. Preferred allophanate catalysts are zinc octoate, tin octoate, zinc 2-ethylhexanoate, tin 2-ethylhexanoate, and zinc acetylacetonate. Suitable examples of allophanate-trimeric catalyst systems for use as c) (3) in the present invention include those systems comprising (a) at least one catalyst capable of forming trimeric groups, and (b) at least one catalyst capable of form allophanate groups. Those skilled in the art are familiar with said trimeric catalysts and allophanate catalysts. In accordance with the present invention, suitable catalyst systems are those which convert at least 50%, preferably at least about 70%, more preferably at least about 80%, more preferably at least about 90% and more particularly preferably at least about 95% of the equivalents of urethane groups to allophanate groups. A preferred allophanate-trimeric catalyst system c) (3) for the present invention comprises: (i) at least one trimeric catalyst selected from the group consisting of: (a) lithium salts of monocarboxylic acids or aliphatic or aromatic carboxylic acids, ( b) lithium salts of compounds containing the hydroxyl group containing 1 to 3 hydroxyl groups per compound, wherein the hydroxyl groups are directly attached to an aromatic ring, (c) lithium hydroxide, and (d) mixtures thereof; and (ii) at least one allophanate catalyst. The allophanate-trimeric catalyst systems for component c) (3) of the present invention include, for example, those described in U.S. Patent Nos. 5,955,609 and 6,127,308, the disclosures of which are incorporated herein by reference. When the preferred allophanate-trimeric catalyst systems are used in the present invention, the molar ratio of allophanate catalyst c) (3) (ii), to lithium compound c) (3) (i) is 20: 1 to 1:20 Based on this it is preferred to use between 5 x 10"6 to 4 x 10" 5 moles of allophanate catalyst, c) (3) (ii) together with 0.015 to 0.2 equivalents of hydroxyl group of the organic compound containing at least a hydroxyl group i.e. component b), per isocyanate equivalent of a) the diphenylmethane diisocyanate present to trimerize. It is more preferable to use from about 5 x 10 ~ 6 to 3.2 x 10"5 moles of allophanate catalyst c) (3) (ii), with the appropriate amount of lithium compound c) (3) (i) as described above and from about 0.01 about 0.20, preferably from about 0.3 to about 0.18 equivalents of hydroxyl group of the organic compound containing at least one hydroxyl group b) per equivalent of isocyanate of MDI to trimerize Catalyst stop elements suitable for use in accordance with the present invention include for example acid catalyst stop elements such as, for example, anhydrous hydrochloric acid, bis (2-ethylhexyl) hydrogen phosphate sulfuric acid, benzoyl chloride, acids of Lewis and the like The preferred catalyst stopping elements are benzoyl chloride and bis (2-ethylhexyl) hydrogen phosphate The amount of stop element used is the amount needed to dispense the activate the catalysts. This will vary depending on the catalyst and stopping element used. In general, however, it is typically necessary between 50 and 100% by weight of the arresting element relative to the weight of the catalyst. The preparation of stable, liquid, allophanate modified, partially trimerized diphenylmethane diisocyanates of the present invention can be made by a variety of different methods or processes. One process simultaneously forms the partially trimerized modified allophanate MDI product which is a stable liquid and another form, first, an allophanate modified MDI and then partially trimerizes some of the remaining NCO groups. In another process, the allophanate-modified MDI and the trimerized MDI are separately formed as individual products and then these two products are mixed together to form the allophanate modified MDI trimers. Below is more detailed information regarding these processes.

In the case where the allophanate and the trimer are prepared simultaneously, the hydroxyl compound is added to the MDI at temperatures between 40 and 80 ° C. The addition of either an allophanate / trimeric catalyst or an allophanate catalyst and a trimeric catalyst can occur before, during or after the addition of the hydroxyl compound. After the desired NCO group content is reached at 70 to 120 ° C, an acid stop element is added and the product is cooled to approximately 25 ° C for storage. In the case where the allophanate is first prepared, the allophanate catalyst can be added before, during or after adding the hydroxyl compound to the MDI. The urethane is then converted to the allophanate modified MDI at temperatures between 70 and 120 ° C, before the addition of the trimeric catalyst. The trimeric catalyst is then added, and the reaction mixture is maintained at a temperature between 70 and 120 ° C, until the desired NCO group content is reached and at this time the acid stop element is added. Then, the product is cooled to approximately 25 ° C for storage. In the embodiment of the present invention, the at least partially liquid, stable, modified, allophanate-modified diphenylmethane diisocyanates having an NCO group content of 15 to 30%, preferably 20 to 28% and more preferably 22 to 26% %, are mixtures of: (A) an allophanate-modified MDI having an NCO group content of 16 to 29%; and (B) a partially trimerized MDI having an NCO group content of 20 to 31%.

These mixtures comprise: (A) from 20 to 65% (preferably from 30 to 60%, more preferably from 35 to 55%) by weight based on 100% by weight of (A) and (B), of a diisocyanate of allophanate-modified diphenylmethane having an NCO group content of from about 16 to about 29%, preferably from about 20 to about 28%, and more preferably from about 21 to about 26%; and (B) from 35 to 80% (preferably from 40 to 70%, more preferably from 45 to 65%) by weight based on 100% by weight of (A) and (B), of a diphenylmethane diisocyanate at least partially trimerized having an NCO group content of from about 20 to about 31%, preferably from about 22 to about 29% and more preferably still from about 24 to about 27%. In these mixtures, the component (A), the allophanate-modified diphenylmethane diisocyanate, comprises the reaction product of: a) (2) a diphenylmethane diisocyanate comprising: (i) from 0 to 60% (preferably 10 to 50%, more preferably from 20 to 40%) by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% (preferably from 0 to 4%, more preferably from 0 to 2%) by weight of 2,2'-diphenylmethane diisocyanate and (iii) 34 to 100% (preferably 50 to 90%, more preferably 60 to 80%) by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight from a) (2) (i), a) (2) (ii) and a) (2) (iii) make a total of 100% by weight of a) (2); and b) an organic compound containing at least one hydroxyl group, in the presence of c) (2) at least one allophanate catalyst. In the allophanate modified diphenylmethane diisocyanates to be used as component (A) in the above mixtures, the suitable organic compounds containing at least one hydroxyl group to be used as component b) and the allophanate catalysts suitable for use as component c) ( 2) are as described above. The amount of component b) present is such that there is from about 0.05 to 0.25 equivalents of hydroxyl group per equivalent of MDI isocyanate present and preferably from about 0.1 to 0.2 equivalents of hydroxyl groups per equivalent of isocyanate of MDI present. furtherAt least about 50% of the urethane groups are converted to allophanate groups by the catalyst. Preferably about 70% more preferably about 80%, more preferably still about 90% and more preferably particularly about 95% of the urethane groups are converted to allophanate groups. Suitable diphenylmethane diisocyanates for use to form the modified allophanate-modified MDI above have NCO group contents of from about 33.0% to about 33.6%, preferably from about 33.4% to about 33.6% and more preferably still about 33.6% and have an isomer distribution as described for component a) (2). In the partially trimerized diphenylmethane diisocyanates to be used as component (B) in the above mixtures, these are the trimerization products of MDI in the presence of a trimeric catalyst. More specifically, it is the trimerization products of: a) (3) a diphenylmethane diisocyanate comprising: (i) from 10 to 60% (preferably from 15 to 50%, more preferably from 20 to 40%) by weight of diisocyanate 2,4'-diphenylmethane, (ii) 0 to 6% (preferably 0 to 4%, more preferably 0 to 2%) by weight of 2,2'-diphenylmethane diisocyanate and (iii) of 90% (preferably 50 to 85%, more preferably 60 to 80%) by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (3) (i), a) (3) ) (ii) ya) (3) (iii) make a total of 100% by weight of a) (3); in the presence of c) (1) at least one trimeric catalyst, wherein the content of the trimer is at least about 10 to about 80%, preferably about 25 about 60% and more preferably about 30 to about 40%, based on 100% by weight of component (B). Suitable diphenylmethane diisocyanates for preparing the trimerized diphenylmethane diisocyanate include those having an NCO group content of from about 33.0% to about 33.6%, preferably from about 33.4% to about 33.6%. % and more preferably still about 33.6% and having an isomer distribution as described above for component a) (3). Suitable trimeric catalysts for this aspect of the invention include those trimeric catalysts c) (1) as described hereinabove for the product prepared with the simultaneous formation of allophanate groups and trimeric groups, or allophanate groups which are formed first and then the trimeric groups are formed. In the urethane prepolymers from liquid at least partially stable trimethylated modified aliphatic modified diphenylmethane diisocyanates of the present invention and the corresponding processes for preparing these, the isocyanate-reactive compounds suitable for the present application, wherein the prepolymers of urethane diisocyanate diphenylmethane, partially trimerized, modified, allophanate, stable, are prepared by reacting partially modified trimerized MDI with allophanate with, for example, (II) an isocyanate-reactive component containing from about 1.5 to about 6 hydroxyl groups capable of reacting with NCO groups, and having molecular weights of from about 76 to about 10,000. Such compounds include, for example, polyether polyols, polyester polyols and diols. These isocyanate-reactive components include those compounds that typically have at least 1.5 hydroxyl groups that are capable of reacting with NCO groups and preferably at least 1.8 hydroxyl groups and more preferably at least 2 hydroxyl groups. These isocyanate-reactive components typically have less than or equal to 6 hydroxyl groups, preferably less than or equal to 5 hydroxyl groups, more preferably less than or equal to 4 hydroxyl groups and more preferably less than or equal to 3 hydroxyl groups. The isocyanate-reactive components can also have a number of hydroxyl groups ranging from any combination of these higher and lower values including for example 1.5 to 6 hydroxyl groups, preferably 1.8 to 6 hydroxyl groups, more preferably 2 to 4 hydroxyl groups and more preferably 2 to 3 hydroxyl groups. In addition, these isocyanate-reactive components typically have a molecular weight of at least 76, preferably at least about 90, more preferably at least about 192 and more preferably at least about 400. Typically, the isocyanate-reactive components also have a molecular weight less than or equal to about 10,000, preferably less than or equal to 6,000, more preferably less than or equal to about 4,800 and more preferably less than or equal to about 4,000. The isocyanate-reactive components may have a molecular weight that varies between any combination of these upper and lower values including for example from 76 to 10,000, preferably from 90 to 6000, more preferably from 192 to 4800 and more preferably even from 400 to 4000. Polyether polyols suitable as isocyanate (II) reactive compounds for this aspect of the present invention include which have hydroxyl functionalities of about 1.5 to about 6, preferably from about 2 to about 3, and molecular weights from about 192 to about 10,000, preferably from about 400 to about 6,000, to produce a urethane prepolymer having an NCO content of from about 8 to about 28%, preferably from about 12 to about 26%. Polyester polyols suitable as isocyanate (II) reactive compounds for this aspect of the present invention include those having hydroxyl functionalities of about 1.8 to about 2, preferably about 2, and molecular weights of about 200 or about 3,000, preferably from about 500 to about 2,000, to produce a urethane prepolymer having an NCO content of from about 8 to about 28%, preferably from about 20 to about 26%. Suitable diols for use as isocyanate-reactive compounds (II) to form urethane prepolymers of partially trimerized modified allophanate MDI include, for example, 1,3-butanediol, propylene glycol 2,2,4-trimethyl-1,3-pentanediol 2- methyl-l, 3-propanediol, dipropylene glycol, tripropylene glycol, diethylene glycol and triethylene glycol. Preferred diols are 1,3-butanediol, propylene glycol, dipropylene glycol and tripropylene glycol. In the process of preparing prepolymers of liquid-stable, partially trimerized modified diphenylmethane diisocyanates, stable, liquid, stable, partially trimerized modified diphenylmethane diisocyanates can be prepared directly as in the previous case, forming the allophanate and the trimer simultaneously or forming the allophanate first and then the trimer or these can be prepared from mixtures of an allophanate-modified diphenylmethane diisocyanate prepared separately and a partially trimerized di-phenylmethane diisocyanate prepared separately. The process for the preparation of urethane polymers of liquid, stable, stable, buffered modified diphenylmethane diisocyanates of the present invention is typically accomplished by adding the appropriate isocyanate-reactive compound to the partially trimerized modified MDI with allophanate while stirring in a nitrogen bed. . The reaction mixture is maintained at a temperature between 40 and 80 ° C, preferably 55 to 65 ° C, for about 1 to 4 hours. When the theoretical NCO group content is reached, the reaction mixture is cooled to approximately 25 ° C during storage. The following examples further illustrate details for the preparation and use of the compositions of this invention. The invention, which is explained in the foregoing description, should not be limited in spirit or scope to these examples. Those skilled in the art will readily understand that known variations of conditions and processes of the following preparation methods can be used to prepare these compositions. Unless otherwise indicated, all temperatures are in degrees centigrade and all parts and percentages are parts by weight and percentages by weight, respectively. EXAMPLES The following processes are suitable for the preparation of allophanate modified MDI trimers of the present invention. There are at least three (3) different processes by which the products of the invention can be prepared. Three (3) of these processes are described below. However, only processes named Process 1 and Process 3 below are used in the working examples of this application. Process 1: (Preparation of the trimer and allophanate simultaneously) The MDI and an organic compound containing at least one hydroxyl group were added to a reactor. When the initial urethane reaction was complete, a trimeric catalyst and optionally an allophanate catalyst were added. The reaction mixture was heated to about 70 to 120 ° C until the desired NCO content was reached. After, an acid stop element was added to neutralize the catalyst and the reaction mixture was then cooled to 25 ° C for storage. Alternatively, the catalyst can be added to the MDI in the reactor before adding the organic compound containing at least one hydroxyl group.

Process 2: (Preparation of the allophanate first, and then the trimer) The MDI and the organic compound containing at least one hydroxyl group were added to a reactor. When the initial urethane reaction was complete, an allophanate catalyst was added. The reaction mixture was heated to about 70 to 120 ° C, until the allophanate reaction was complete or for about 60 minutes. A trimeric catalyst was then added and the reaction mixture was maintained at about 70 to 120 ° C until the desired NCO content was reached. An acid stop element was then added to neutralize the catalysts and the reaction mixture was then cooled to 25 ° C for storage. Alternatively, the allophanate catalyst can be added to the MDI before adding the organic compound containing at least one hydroxyl group. Process 3: (Preparation of the allophanate and the trimer separately and then mixed together) A) The MDI and an organic compound containing at least one hydroxyl group were added to a reactor. When the initial urethane reaction was complete, an allophanate catalyst was added. The reaction mixture was heated to about 70 to 120 ° C until the allophanate reaction was complete or for about 60 minutes. Then, an acid stop element was added to neutralize the catalyst and the reaction mixture was then stored between 25 and 60 ° C. Alternatively, the catalyst can be added to the MDI before adding the organic compound containing at least one hydroxyl group.

B) The MDI was added to a reactor at approximately 40 ° C.

To the MDI, a trimeric catalyst was added followed by heating to about 70 to 120 ° C until the desired NCO content was reached. Then, an acid stop element was added to neutralize the catalyst.

The reaction mixture was stopped, maintaining at a temperature between 60 and 100 ° C which was mixed with the product of A) earlier in the desired proportion and then cooled to ° C for storage. They used the following materials in the working examples to demonstrate the allophaneized and partially trimerized, liquid, stable MDI. MDI-1 an isomeric mixture of diphenylmethane diisocyanate having an NCO content of about 33.6%, and comprising about 98.4% by weight of 4,4'-diphenylmethane diisocyanate and about 1.6 % by weight of 2,4,4'-diphenylmethane diisocyanate MDI-2 an isomeric mixture of diphenylmethane diisocyanate having an NCO content of about 33.6% and comprising about 45.8% by weight of 4.4 '-MDI, approximately 52.8% by weight of 2,4'-MDI and approximately 1.4% by weight of 2,2'-MDI Alcohol To Isobutyl Alcohol Catalyst Mutilen-bis (3,3 ', 5,5' -tetradimethylaminomethyl-A 2,2'-phenol) Catalyst Zinc Acetylacetonate B Element Benzoyl Chloride for acid detention Example 1: 120 parts of MDI-1 and 80 parts of MDI-2 were charged to a stirred reactor and maintained at 50 ° C. To this was added 8 parts of alcohol A and 0.02 parts of catalyst B. The mixture was maintained at 90 ° C for about 30 minutes followed by the addition of 0.042 parts of catalyst A. After about 1.5 additional hours at 90 ° C, 0.015 part of benzoyl chloride was added and the reaction mixture was cooled to 25 ° C. The clear liquid product had an NCO content of 26.1% and a viscosity at 25 ° C of 190 Pa.s. The examples shown in Table 1 were prepared according to Example 1. Examples 2-17 resulted in clear liquid products.

Table 1 Eem the readings according to Example 1) 15 20 fifteen twenty Jilo • o- 15 twenty The following comparative examples showed that more than 38% by weight of 2,4'-MDI is necessary to obtain a stable modified trimer-modified MDI. Example 18: To a stirred reactor was added 100 parts of MDI-1 and 100 parts of MDI-2. The mixture was heated to 90 ° C and 250 ppm of catalyst A was added. The reaction mixture was maintained at 90 ° C for about 3 hours followed by the addition of 100 ppm of benzoyl chloride. The reaction mixture was cooled to 25 ° C. The partially trimerized MDI had an NCO content of 30, 6%. During storage at 25 ° C, the product became turbid with approximately 15% solids. The experiment was repeated up to 29.6% of NCO with the same results. Example 19: Example 18 was repeated with 60 parts of MDI-1 and 140 parts of MDI-2 to an NCO content of 30.6%. The product was cloudy with 10% solids. This was repeated up to 29.7% of NCO with the same results. The following example was prepared according to Process 3 to produce an MDI modified with stable liquid partially trimerized allophanate. Example 20: A) To a stirred reactor were added 100 parts of MDI-1 and 9.4 parts of alcohol A. After about 15 minutes, the initial urethane reaction was complete. The reaction mixture was then heated under a nitrogen atmosphere at 90 ° C and 100 ppm of catalyst B was added. The reaction mixture was maintained at 90 ° C for 90 minutes, followed by the addition of 150 ppm of benzoyl chloride . The reaction mixture was then cooled to 25 ° C. The MDI product modified with clear liquid allophanate had an NCO content of 21.0%. B) To a stirred reactor was added 30 parts of MDI-1 and 70 parts of MDI-2. To this mixture at 90 ° C under nitrogen atmosphere, 300 ppm of catalyst A was added. After about 3 hours at 90 ° C, 100 ppm of benzoyl chloride was added and then the reaction mixture was cooled to about 60 minutes. ° C. The clear liquid partially trimerized MDI product had an NCO content of 25.9%. A mixture was prepared according to Process 3 by mixing 38% by weight of the product of A) with 62% by weight of product of B) to produce a final mixed product with an NCO content of about 24.0% and a viscosity at 25 ° C of about 2526 mPa.s. The product prepared in B) above, a partially trimerized MDI, when cooled to 25 ° C became turbid with solids. The following materials were used in the preparation of the partially trimerized MDI prepolymers modified with allophanate. ISO A: the partially trimerized MDI modified with allophanate of Example 15, characterized by an NCO content of about 25.2% and a viscosity at 25 ° C of about 760 mPa.s ISO B: the partially trimerized MDI modified with allophanate Example 17, characterized by an NCO content of about 25.9% and a viscosity at 25 ° C of about 380 mPa.s XB: 1,3-butanediol Polyol of a propylene glycol / oxide adduct Polyether A: propylene having a molecular weight of about 1000 and a functionality of about 2. Polyol of a propylene glycol / polyether B: propylene adduct having a molecular weight of about 2000 and a functionality of about 2.

Example 21: 100 parts of ISO A were charged to a reactor with a stirrer and a nitrogen atmosphere. The contents of the reactor were heated to 60 ° C with stirring. Then 2.8 parts of XB were added and the reaction mixture was kept at 60 ° C for 2 hours, and then cooled to 25 ° C. The clear liquid prepolymer had an NCO content of about 22.0% and a viscosity at 25 ° C of about 86,000 mPa.s. Example 22: Using the procedure as described above in Example 21, 100 parts of ISO A and 17.2 parts of Polyether Polyol A were reacted to produce a clear liquid prepolymer having an NCO content of about 20%. , 3% and a viscosity at 25 ° C of approximately 11,200 mPa.s. Example 23: Using the procedure as described above in Example 21, 100 parts of ISO A and 20.1 parts of Polyether Polyol B were reacted to produce a clear liquid prepolymer having an NCO content of about 20.2% and a viscosity at 25 ° C of about 8,200 mPa.s. Example 24: Using the procedure as described above in Example 21, 100 parts of ISO B and 16.7 parts of Polyether Polyol A were reacted to produce a clear liquid prepolymer having an NCO content of about 21%. , 0% and a viscosity at 25 ° C of approximately 2,080 mPa.s. Example 25: Using the procedure as described above in Example 21, 100 parts of ISO B and 2.85 parts of XB were reacted to produce a clear liquid prepolymer having an NCO content of about 22.6% and a viscosity at 25 ° C of about 22,500 mPa.s.

Although the invention has been described in detail in the foregoing for purposes of illustration, it should be understood that such detail is solely for this purpose and that those skilled in the art can make variations without departing from the spirit and scope of the invention except as limited by The claims.

Claims

1. A stable, liquid, partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of 15 to 30% and comprising the reaction product of: a) (1) a diphenylmethane diisocyanate comprising: (i) ) from 10 to 40% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 54 to 90% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (1) (i), a) (1) (ii) and a) (1) (iii) make a total of 100% by weight of a ) (1); and b) an organic compound containing at least one hydroxyl group, in the presence of a catalytic amount of: c) at least one catalyst selected from a group consisting of (1) one or more trimeric catalysts, (2) one or more catalysts of allophanate, (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof; where component b) is present in an amount such that from about 0.01 to about 0.25 equivalents of hydroxyl groups per equivalent of MDI isocyanate present, at least about 50% of the urethane groups are converted into allophanate groups by c) said catalyst or catalyst system, and a catalyst stop element is added once the desired NCO group content has been reached.

2. The stable, liquid-phase, modified, allophanate modified diphenylmethane diisocyanate of claim 1, wherein the NCO group content is 20 to 28%.

3. The liquid, stable, stable, modified, allophanate modified diphenylmethane diisocyanate of claim 1, wherein a) (1) said diphenylmethane diisocyanate comprises (i) from 20 to 35% by weight of the 2,4'-isomer; (ii) from 0 to 2% by weight of the 2,2'-isomer, and (iii) from 63 to 80% by weight of the 4,4'-isomer, whereby the weight% of a) (1) (i), a) (1) (ii) ya) (1) (iii) a total of 100% by weight of a) (1).

4. The stable, liquid-buffered, modified, allophanate-modified diphenylmethane diisocyanate of claim 1, wherein component b) is present in an amount such that there is from about 0.01 to 0.20 equivalents of hydroxyl groups per equivalent of isocyanate of diphenylmethane diisocyanate present.

5. The stable, liquid-buffered, modified, allophanate-modified diphenylmethane diisocyanate of claim 1, wherein at least about 70% of the urethane groups are converted to allophanate groups by c) said catalyst.

6. The stable, liquid-phase, modified, allophanate modified diphenylmethane diisocyanate of claim 1, wherein the allophanate groups and the trimeric groups were formed simultaneously.

7. The liquid-stabilized, partially trimerized diphenylmethane diisocyanate, stable, of claim 1, wherein the allophanate groups were first formed, and then the trimeric groups were formed.

8. The stable, liquid-buffered, modified, allophanate modified diphenylmethane diisocyanate of claim 1, wherein b) said organic compound has a molecular weight of from about 32 to about 6,000 and contains from about 1 to about 4 hydroxyl groups.

9. The stable, liquid-buffered, partially-trimethylated diphenylmethane diisocyanate diisocyanate of claim 1, wherein b) comprises 2-propanol or isobutyl alcohol.

10. A process for the preparation of a partially trimerized diphenylmethane diisocyanate, modified with stable allophanate, liquid, having an NCO group content of 15 to 30%, comprising: (1) heating a) (1) a diphenylmethane diisocyanate comprising: (i) from 10 to 40% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 54 to 90% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (1) (i), a) (1) (ii) and a) (1) (iii) make a total of 100 % by weight of a) (1); and b) an organic compound containing at least one hydroxyl group, at a temperature of about 70 to 120 ° C for a period of about 1 to about 6 hours, in the presence of a catalytic amount of: c) at least one catalyst selected from the group consisting of (1) one or more trimeric catalysts, (2) one or more allophanate catalysts, (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof; wherein the amount of b) is such that there is from about 0.01 to about 0.25 equivalents of hydroxyl groups per equivalent of MDI isocyanate present, and at least about 50% of the urethane groups are converted to allophanate groups by ) said catalyst or catalysts, and (2) adding a catalyst stop element once the desired NCO group content of the reaction mixture in (1) is reached to neutralize the catalyst in the reaction mixture.

11. The process of claim 10, wherein the NCO group content is from 20 to 28%.

12. The process of claim 10, wherein a) (1) said diphenylmethane diisocyanate comprises (i) from 20 to 35% by weight of the 2,4'-isomer, (ii) from 0 to 2% by weight of the 2-isomer. , 2 ', and (iii) from 63 to 80% by weight of the 4,4' isomer, the% by weight of a) (1) (i), a) (1) (ii) already) (1) (iii) a total of 100% by weight of a) (1).

13. The process of claim 10, wherein component b) is present in an amount such that there is from about 0.01 to 0.20 equivalents of hydroxyl groups per isocyanate equivalent of the diphenylmethane diisocyanate present.

14. The process of claim 10, wherein at least about 70% of the urethane groups are converted to allophanate groups by c) said catalyst.

15. The process of claim 10, wherein c) the catalyst is selected such that the allophanate groups and the trimeric groups are formed simultaneously.

16. The process of claim 10, wherein c) the catalyst is selected such that the allophanate groups are first formed, and then another suitable catalyst c) is added so that the trimeric groups are formed.

17. The process of claim 10, wherein b) said organic compound has a molecular weight of from about 32 to about 6,000 and contains from about 1 to about 4 hydroxyl groups.

18. The process of claim 10, wherein b) comprises 2-propanol or isobutyl alcohol.

19. A stable, liquid, partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of 15 to 30% and comprising: (A) from 20 to 65% by weight, based on 100% by weight of (A) and (B), of an allophanate-modified diphenylmethane isocyanate having an NCO group content of about 16 to about 29%, and is the reaction product of: a) (2) a diphenylmethane diisocyanate comprising (i) from 0 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 34 to 100% % by weight of diisocyanate 4,4'-diphenylmethane, where the percentages by weight of a) (2) (i), a) (2) (ii) and a) (2) (iii) make a total of 100% by weight of a) ( 2), and b) an organic compound containing at least one hydroxyl group, in the presence of: c) (2) one or more allophanate catalysts, where component b) is present in an amount such that there is about 0.05 at about 0.25 equivalents of hydroxyl groups per equivalent of MDI isocyanate present, at least about 50% of the urethane groups is converted to allophanate groups by c) (2), and a catalyst stop element is added once achieved the desired NCO group content of the allophanate modified MDI; and (B) from 35 to 80% by weight, based on 100% by weight of (A) and (B), of a partially trimerized diphenylmethane diisocyanate having an NCO group content of from about 20 to about 30. %, and is the trimerization product of: (a) (3) a diphenylmethane diisocyanate comprising (i) from 10 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% in weight of 2,2'-diphenylmethane diisocyanate, and (iii) 34 to 90% by weight of diisocyanate of 4,4'-diphenylmethane, where the percentages by weight of a) (3) (i), a) (3) (ii) and a) (3) (iii) make a total of 100% by weight of a) ( 3), in the presence of c) at least one catalyst selected from the group consisting of (1) one or more trimeric catalysts, (3) an allophanate-trimeric catalyst system, and (4) mixtures thereof; wherein the trimeric content is at least about 10 to about 80% by weight, based on 100% by weight of component (B), and a catalyst stop element is added once the desired NCO group content of the catalyst has been reached. MDI modified with the trimer.

20. The mixture of claim 19 having an NCO group content of 20 to 28%, and comprising: (A) from 30 to 60% by weight based on 100% by weight of (A) and (B), an allophanate-modified diphenylmethane diisocyanate having an NCO group content of from about 20 to about 28%, and (B) from 40 to 70% by weight, based on 100% by weight of (A) and (B) ), of at least partially trimerized diphenylmethane diisocyanate having an NCO group content of about 22 to about 29%.

21. The mixture of claim 19, wherein: (A) said allophanate-modified diphenylmethane diisocyanate comprises the reaction product of: a) (2) a diphenylmethane diisocyanate comprising: (i) from 10 to 50% by weight of 2,4'-diphenylmethane diisocyanate, (ii) 0 to 4% by weight of 2,2'-diphenylmethane diisocyanate and (iii) 50 to 90% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (2) (i), a) (2) (ii) and a) (2) (iii) make a total of 100% by weight of a) (2); b) an organic compound having a molecular weight of from about 32 to about 6,000 and containing from at least about 1 to about 4 hydroxyl groups; in the presence of c) one or more allophanate catalysts.

22. The mixture of claim 19, wherein in (A) the allophanate-modified diphenylmethane diisocyanate, the amount of b) is such that there are from about 0.10 to 0.20 equivalents of hydroxyl groups per isocyanate equivalent of MDI present, and at least about 70% of the urethane groups are converted to the allophanate group.

23. The mixture of claim 19, wherein (B) said trimerized diphenylmethane diisocyanate comprises the trimerization product of a) (3) a diphenylmethane diisocyanate comprising the reaction product of: (i) from 20 to 40% in weight of 2,4'-diphenylmethane diisocyanate, (ii) 0 to 2% by weight of 2,2'-diphenylmethane diisocyanate and (iii) 60 to 80% by weight of 4,4'-diphenylmethane diisocyanate , where the percentages by weight of a) (3) (i), a) (3) (ii) and a) (3) (iii) make a total of 100% by weight of a) (3); in the presence of: c) at least one catalyst selected from the group consisting of (1) one or more trimeric catalysts, (3) a trimeric-allophanate catalyst system and (4) mixtures thereof; wherein the trimer content is at least about 25 to about 60%, based on 100% by weight of component (B).

24. The mixture of claim 19, wherein b) said organic compound has a molecular weight of about 32 to about 6,000 and contains from about 1 to about 4 hydroxyl groups.

25. The mixture of claim 19, wherein b) comprises 2-propanol or isobutyl alcohol.

26. A process for the preparation of partially purified trimerized diphenylmethane diisocyanate, liquid allophanate, stable, having an NCO group content of 15 to 30% and comprising: (1) mixing (A) from 20 to 65% by weight , based on 100% by weight of (A) and (B), of an allophanate-modified diphenylmethane isocyanate having an NCO group content of from about 16 to about 29%, and comprising the reaction product of a) (2) a diphenylmethane diisocyanate comprising (i) from 0 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate , and (iii) from 34 to 100% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (2) (i), a) (2) (ii) and a) (2) (iii) make a total of 100% by weight of a) (2), with b) an organic compound containing at least one hydroxyl group, in the presence of: c) (2) one or more allophanate catalysts, where thecomponent b) is present in an amount such that from about 0.05 to about 0.25 equivalents of hydroxyl groups per equivalent of MDI isocyanate present, at least about 50% of the urethane groups is converted to allophanate groups by ) (2) and a catalyst stop element is added once the desired NCO group content of the allophanate modified MDI is reached; with (B) from 35 to 80% by weight, based on 100% by weight of (A) and (B), of at least one partially trimerized diphenylmethane diisocyanate having an NCO group content of about 20 to about 31, and is the trimerization product of: (a) (3) a diphenylmethane diisocyanate comprising (i) from 10 to 60% by weight of 2,4'-diphenylmethane diisocyanate, (ii) from 0 to 6% by weight of 2,2'-diphenylmethane diisocyanate, and (iii) from 34 to 90% by weight weight of 4,4 '-diphenylmethane diisocyanate, where the percentages by weight of a) (3) (i), a) (3) (ii) and a) (3) (iii) make a total of 100% by weight from a) (3), formed in the presence of: c) at least one catalyst selected from the group consisting of (1) one or more trimeric catalysts, (3) an allophanate-trimeric catalyst system, and (4) mixtures of the same; where the trimeric content is at least about 10 to about 80%, based on the 100% by weight of component (B), and a catalyst stop element is added once the desired NCO group content is reached, and (2) cooling the mixture to room temperature.

27. The process of claim 26, having an NCO group content of 20 to 28% and comprising: (A) from 30 to 60% by weight, based on 100% by weight of (A) and (B) of an allophanate-modified diphenylmethane diisocyanate having an NCO group content of from about 20 to about 28%, and (B) from 40 to 70% by weight, based on 100% by weight of (A) and (B) ) of at least partially trimerized diphenylmethane diisocyanate having an NCO group content of about 22 to about 29%.

28. The process of claim 26, wherein: (A) said allophanate-modified diphenylmethane diisocyanate comprises the reaction product of: a) (2) a diphenylmethane diisocyanate comprising: (i) from 10 to 50% by weight of 2,4'-diphenylmethane diisocyanate, (ii) 0 to 4% by weight of 2,2'-diphenylmethane diisocyanate and (iii) 50 to 90% by weight of 4,4'-diphenylmethane diisocyanate, where the percentages by weight of a) (2) (i), a) (2) (ii) and a) (2) (iii) make a total of 100% by weight of a) (2); b) an organic compound having a molecular weight of from about 32 to about 6,000 and containing from about 1 to about 4 hydroxyl groups; in the presence of c) one or more allophanate catalysts.

29. The process of claim 26, wherein (A) the allophanate-modified diphenylmethane diisocyanate, the amount of b) is such that there are from about 0.01 to 0.20 equivalents of hydroxyl groups per isocyanate equivalent of the diisocyanate of MDI present, and at least about 70% of the urethane groups are converted to allophanate groups.

30. The process of claim 26, wherein (B) said trimerized diphenylmethane diisocyanate comprises the trimerization product of a) (3) a diphenylmethane diisocyanate comprising the reaction product of: (i) from 20 to 40% in weight of 2,4'-diphenylmethane diisocyanate, (ii) 0 to 2% by weight of 2,2'-diphenylmethane diisocyanate and (iii) 60 to 80% by weight of 4,4'-diphenylmethane diisocyanate , where the percentages by weight of a) (3) (i), a) (3) (ii) and a) (3) (iii) make a total of 100% by weight of a) (3); in the presence of: c) at least one catalyst selected from the group consisting of (1) one or more trimeric catalysts, (3) a trimeric-allophanate catalyst system and (4) mixtures thereof; wherein the trimer content is at least about 25 to about 60%, based on 100% by weight of component (B).

31. The process of claim 26, wherein b) said organic compound has a molecular weight of from about 32 to about 6,000 and contains from about 1 to about 4 hydroxyl groups.

32. The process of claim 26, wherein b) comprises 2-propanol or isobutyl alcohol.

33. A liquid urethane polymer, stable during storage of a partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of 8 to 28% and comprising the reaction product of: (I) partially trimerized diphenylmethane diisocyanate, modified with allophanate, liquid, stable during storage of claim 1, and (II) an isocyanate-reactive component containing from about 1.5 to about 6 hydroxyl groups and having a molecular weight of from about 76 to about 10,000.

34. The liquid urethane prepolymer, stable during storage of claim 33, wherein the content of the NCO group is from about 12 to about 26%.

35. The storage stable, liquid urethane prepolymer of claim 33, wherein (II) said isocyanate-reactive component contains from 2 to 6 hydroxyl groups and has a molecular weight of from about 90 to about 6,000.

36. A process for the preparation of a liquid urethane polymer, stable during storage of a partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of about 8 to about 28, comprising: (1) reacting: (I) the liquid-stable, partially trimerized diphenylmethane diisocyanate, stable during storage, of claim 1, with (II) an isocyanate-reactive component containing from about 1.5 to about 6 hydroxyl groups and having a molecular weight of about 76 to about 10,000, at a temperature of 40 to 80 ° C for 1 to 6 hours.

37. The process of claim 36, wherein the NCO group content is from about 12 to about 26%.

38. The process of claim 36, wherein (II) said isocyanate-reactive component contains from 2 to 6 hydroxyl groups and has a molecular weight of from about 90 to about 6,000.

39. A liquid urethane prepolymer, stable during storage of a partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of 8 to 28%, which comprises the reaction product of: (III) the diisocyanate of dipropylmethane partially trimerized, modified with allophanate, liquid, stable during storage of claim 19, and (II) an isocyanate-reactive component containing from about 1.5 to about 6 hydroxyl groups and having a molecular weight of about 76 to approximately 10,000.

40. The prepolymer of claim 39, wherein the NCO group content is from about 12 to about 26%.

41. The prepolymer of claim 39, wherein (II) said isocyanate-reactive component contains from 2 to 6 hydroxyl groups and has a molecular weight of from about 90 to about 6,000.

42. A process for the preparation of a liquid urethane prepolymer, stable during storage of a partially trimerized diphenylmethane diisocyanate, modified with allophanate, having an NCO group content of 8 to 28%, which comprises: (1) reacting: (I) the partially trimerized diphenylmethane diisocyanate, modified with allophanate, liquid, stable during storage, of claim 19, and (II) an isocyanate-reactive component containing from about 1.5 to about 6 hydroxyl groups and having a molecular weight of about 76 to about 10,000, at a temperature of 40 to 80 ° C for 1 to 6 hours.

43. The process of claim 42, wherein the NCO group content is from about 12 to about 26%.

44. The process of claim 42, wherein (II) said isocyanate-reactive component contains from 2 to 6 hydroxyl groups and has a molecular weight of from about 90 to about 6,000.