MXPA01004263A - Polyurethane prepolymers having alkoxysilane end groups, method for the production thereof and their use for the production of sealants - Google Patents

Abstract

The invention relates to polyurethane prepolymers having terminal alkoxysilane groups based on special high molecular weight polyurethane prepolymers, also to a method for the production thereof and for their use as binding agents or binders for low molecular weight sealants.

Description

POLYURETHANE PREPOLYMERS COMPRISING GROUPS ALCOXISILANOS TERMINALES, PROCEDURE FOR ITS PREPARATION AND ITS USE FOR THE MANUFACTURE OF SEALANTS. FIELD OF THE INVENTION. The invention relates to polyurethane prepolymers comprising terminal alkoxysilane groups based on special polymers of high molecular weight polyurethanes, a process for their manufacture as well as their application as a binding agent or binder for low modulus sealing materials. Functional polyurethanes alkoxysilanes, which crosslink through a polycondensation of silanes, have been known for a long time. An important article regarding this subject is found, for example, in "Adhesives Age" 4/1995, page 30 et seq. (Authors Ta-Min Feng, BA Waldmann) Such polyurethanes of simple components hardenable by moisture, terminated in alkoxysilanes, are they increasingly use as flexible coating compositions, sealants, and adhesives in the construction industry and in the automotive industry. In these applications, high demands are placed on the expansion and adhesion capacities and the hardening speed.

REF: 128477 In particular, the level of properties required in the field of construction can not be fully achieved with existing systems in the current state of the art. EP-A 596 360 discloses functional pbliurethane prepolymers of alkoxysilanes which are suitable as binding agents or binders for sealing materials. The products explicitly described in this patent application, however, are not suitable for the preparation of flexible low modulus sealants such as those used in the field of construction. The profile of properties for sealing materials in the field of construction is specified in detail in the German Industry Standard DIN ISO 11600. The same observation is found in view of the patent applications recently published in EP-A 596 360 , properly EP-A 831 108 and EP-A 807 649. The products described in these patents of the state of the art are suitable for the preparation of high modulus sealants as they are used in the engineering field but not for the preparation of low module sealers for construction.

The object of the present invention is therefore to prepare polyurethane prepolymers having terminal alkoxysilane groups which are suitable as binding agents or binders for the preparation of low modulus sealants. This task can be solved with the preparation of the polyurethane prepolymers comprising terminal alkoxysilane groups which will be described in detail below on the basis of special high molecular number polyurethane prepolymers. The present invention relates to polyurethane prepolymers having terminal alkoxysilane groups which are produced by the reaction of: A) linear polyurethane prepolymers produced by the reaction of: i) an aromatic, aliphatic or cycloaliphatic diisocyanate component having an NCO content of 20 to 60% by weight with ii) a polyol component that includes as a main component a polyoxyalkylene diol which has a molecular weight of 3000 to 20,000, with B) compounds having alkoxysilane and amino groups of the formula (I) in which R and R 'represent the same or different alkyl radicals with 1 to 8 carbon atoms, preferably 1 to 4 carbon atoms and X, Y, Z represent the same or different C? -C8 alkyl-alkyl or C? -C8-alkoxy radicals comprising from 1 to 4 carbon atoms with the proviso that at least one of the radicals represents an alkoxy group C? -C8, characterized in that the polyurethane prepolymers A) have an average molecular weight from the NCO content and the NCO functionality of 15,000 to 50,000 preferably 20, 000 to 40,000. X, Y and Z in the formula (I), independent of each other, preferably represent methoxy or ethoxy. The present invention also relates to a process for the preparation of polyurethane prepolymers having terminal alkoxysilane groups, by the reaction of A) linear polyurethane prepolymers of an average molecular weight calculated from the NCO content and the NCO functionality of 15,000 to 50,000 with B) compounds having alkoxylane groups and amino groups of the formula (I) 0). wherein R and R 'represent the same or different alkyl radicals, comprising from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms and X, Y, Z represent the same or different alkyl or alkoxy radicals comprising 1 to 8 carbon atoms; to 4 carbon atoms with the proviso that at least one of the radicals represents an alkoxy group, characterized in that the polyurethane prepolymer radicals A) have an average molecular weight calculated from the NCO content and the NCO functionality of ,000 to 50,000.

The invention has presented the surprising observation that special polyurethane prepolymers comprising terminal alkoxysilane groups, which have a very high molecular weight, despite the low number in crosslinking positions, harden adhesion-free and can be processed to form materials of sealed that exhibit good elastomeric properties. The isocyanate prepolymers A) to be used according to the invention are prepared in the manner and manner known in polyurethane chemistry by the reaction of a diisocyanate component i) with a polyol component ii) characterized in more detail below. Any aromatic, aliphatic, or cycloaliphatic diisocyanates that exist in the state of the art with an isocyanate content of 20 to 60% by weight can be used as a polyisocyano component i). The terms 'aromatic' and 'cycloaliphatic' diisocyanates comprise those diisocyanates which contain at least one aromatic or cycloaliphatic ring per molecule, where preferably, but not necessarily, at least one of the two isocyanate groups is directly linked to an aromatic ring or cycloaliphatic Substances which are suitable and which are preferred as component i) or as part of component i), are aromatic or cycloaliphatic diisocyanates with a molecular weight range of 174 to 300 such as 4,4'-diphenylmethane diisocyanate, optionally mixed with 2,4'-diphenylmethane diisocyanate, 2,4-diisocyanate toluene and industrial mixtures thereof with preferably up to 35% by weight with reference to the toluene mixture of 2,6-diisocyanate, l-isocyanate-3, 3, 5-trimethyl-5-isocyanate ethylcyclohexane (IPDI), bis- (4-isocyanatocyclohexyl) methane, l-isocyanato-l-methyl-4 (3) -isocyanato-methyl-cyclohexane, and 1,3-diisocyanate- 6-methylcyclohexane, optionally in the mixture with 1,3-diisocyanato-2-methylcyclohexane. Mixtures of the aforementioned isocyanates are also used. Especially preferred as components i) are also used methylcyclohexane of 1-isocyanate-3, 3, 5-trimethyl-5-isocyanide (IPDI) and / or toluene 2,4-diisocyanate and industrial mixtures thereof with preferably up to 35% by weight with respect to the mixture of toluene 2,6-diisocyanate. For the preparation of the polyurethane prepolymer A), the diisocyanate component i) is reacted with a polyol component ii). The polyol component ii) contains as its main component a diol polyoxyalkylene having a molecular weight of 3,000 to 20,000 (corresponding to an OH number of 37.3 to 5.6), preferably 4,000 to 15,000 (corresponding to an OH number of 28 to 7.5). The polyoxyalkylene diols which are preferably used according to the invention are those of the type known in the state of the art from the chemistry of polyurethanes, such as those that can be produced by ethoxylation and / or propoxylation of suitable initial molecules. Examples of suitable starting molecules include diols such as ethylene glycol, propylene glycol, 1,3-butanediol, 1,4-butanediol, 1,6-hexanediol; 2-ethylenehexandiol-l, 3 and also include primary monoamines such as aliphatic amines, for example, ethylamine or butylamine. The polyoxyalkylene diols which are preferably used have an average molecular weight calculated from the OH content and functionality of 3,000 to 20,000 preferably 4,000 to 15,000 and an ethylene oxide content of a maximum of 20% by weight with respect to the total weight of the polyoxyalkylene diol. Very particularly preferred as components are ii) polypropylene oxide polyethers with a total degree of unsaturation of at most 0.04 mq / g and an average molecular weight of OH content and functionality of 8,000 to 12,000.

The polyether polyols preferably used according to the invention with a low degree of unsaturation are known in principle and are described, for example, in EP-A 283 148; US-A 3 278 457; US-A 3 427 256; US-A 3 829 505, US-A 4 472 560; US-A 3 278 458; US-A 3 427 334; US-A 3 941 849; US-A 4 721 818; US-A 3 278 459; US-A 3 427 335; US-A 4 355 188. The polyether polyols which can be used according to the invention, have a low degree of unsaturation and are preferably prepared using metal cyanides as catalysts. The fact is that polyether polyols with low degree of unsaturation, which are preferably used, can be used particularly advantageously, for the preparation of flexible and low modulus sealants, which should be noted as surprising, since according to the state of the technique, polyurethanes that are more rigid and have higher moduli are produced by the use of this type of polyols. Even more, during the production of NCO prepolymers A), subsidiary amounts of bivalent or trivalent alcohols of low molecular weight of molecular weight from 32 to 500 can be used together. Ethylene glycol, 1,3-butanediol, 1-4 are mentioned as an example. -butanediol, 1,6-hexanediol, glycerin or trimethylol propane. The combined use of low molecular weight alcohols, however, is by no means preferred.

Even more, during the production of the NCO prepolymer A) other subsidiary amounts of polyfunctional polyether polyols of the state of the art can be used together, however, this is also not preferred. The production of polyurethane prepolymers can be used according to the invention as component A) and is carried out by the reaction of the diisocyanate component i) with the diol component ii) within the temperature range of 40 to 120 ° C, preferably 50 at 100 ° C maintaining an NCO / OH equivalent ratio of 1.2: 1 to 1.8: 1, preferably 1.3: 1 to 1.6: 1. During the production of polyurethane prepolymers, the catalysts known per se by the chemistry of polyurethanes in the state of the art are either organometallic or amine. The polyurethane prepolymers A), which can be used according to the invention, have an NCO content of 0.21 to 0.56%, preferably 0.28 to 0.42%, corresponding to an average molecular weight of 15,000 to 50,000 preferably 20,000 to 40,000.

The polyurethane prepolymers A) which can be used according to the invention are reacted with compounds of the formula (I) wherein R and R 'represent the same or different alkyl radicals comprising from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms, very especially from 1 to 2 carbon atoms are preferred. and X, Y, Z represent the same or different alkyl or alkoxy radicals comprising from 1 to 4 carbon atoms with the proviso that at least one of the three radicals, and preferably the three radicals, represents a C? -C8 alkoxy group.

The production of compounds having alkoxylane and amino groups used according to the invention is carried out as described in EP-A 596 360 by the reaction of amino alkyl alkoxysilanes of the formula ii) KjN-ÍCr.fc-S? TY ( II), wherein X, Y, Z have the meaning given in formula (I) with esters of maleic and / or fumaric acid of the formula (III) ROOC CH CH COOR1 (III) in which R and R 'independently represent a of the other C? -C8 alkyl Examples of suitable aminoalkyl alkoxysilanes of the formula (II) are 3-aminopropyltrimethoxysilane; 3-aminopropyltriethoxysilane, and 3-aminopropyl-methyl-diethoxy-silane; 3-aminopropyltrimethoxysilane and 3-aminopropyltrilettoxysilane are particularly preferred. The reaction of the NCO prepolymers with the compounds of the formula (I) having the alkoxysilanes and amino groups in the process according to the invention is carried out within a temperature range of 0 to 150 ° C, preferably 20-80 ° C, where the proportion of quantities is generally selected in such a way that per molecule of the NCO groups is applied from 0.95 to 1.1 mol of aminosilyl compound. Preferably per molecule of the NCO groups, 1 mole of aminosilyl compound is used.

In the application of higher reaction temperatures, according to the teaching of EP-A 807 649, a cyclocondensation reaction can be used. However, it does not mean that it is in any way annoying and over time it can be advantageous. The present invention also relates to the use of polyurethane prepolymers comprising terminal alkoxysilane groups as binding agents or binders for the preparation of isocyanate-free low modulus polyurethane sealing materials for the field of construction. These sealing materials crosslink under the effect of air humidity by means of a silane polycondensation.

For the production of such sealing materials, the polyurethane prepolymers having terminal alkoxysilane groups according to the invention can also be formulated together with plasticizers, filler additives, pigments, driers, additives, light-protecting agents, antioxidants, thixotropic agents , catalysts, or adhesive agents and optionally with other adjuvants and additives, according to the known methods for the production of sealants.

Suitable filler additives are, for example, carbon black, silica precipitation acids, mineral grains and precipitation gels. Examples of suitable plasticizers are phthalic acid ester, adipic acid ester, phenol alkyl sulphonic acid ester or phosphoric acid ester. As the thixotropic agent, for example, pyrogenic silica acids, polyamide, products derived from hydrated castor oil or also polyvinyl chloride have been mentioned. Suitable catalysts for curing can be organic tin compounds and amino catalysts. As organotin compounds, for example, dibutyltin diacetate, dibutyltin dilaurate, dibutyltin bis-acetoacetonate and tin carboxylates, such as, for example, tin octoates, can be mentioned. The aforementioned tin catalysts can optionally be used in combination with amine catalysts such as aminosilanes or diazabicyclooctane. As the drying agents, alkoxysilyl compounds, such as vinyl trimethoxysilane, methyl trimethoxysilane, i-butyl trimethoxysilane, hexadecyl trimethoxysilane, have been especially mentioned. The known functional silanes, such as aminosilane of the aforementioned type, for example ammoethyl-3-aminopropyl-trimethoxy and / or dimethoxysilane N-aminoethyl-3-aminopropyl-methyl epoxy silane and / or mercaptosilane, are used as adhesion means. The crosslinked polymers are characterized by an outstanding extensibility for their low modules. Especially products based on polyoxypropylene glycols used as diol components ii), with a low degree of unsaturation and characterized by low modulus, excellent mechanical properties and poor surface adhesion.

EXAMPLES EXAMPLE 1. 4,000 g of a polypropylene glycol of the OH number of 14 with a degree of unsaturation of 0.005 mEq / g (Acclaim 8200 of the Arc) are prepolymerized with 166.5 g isophorous disocyanate at 100 ° C until the theoretical content is reached NCO of 0.5%. The polyurethane prepolymer obtained has a calculated average molecular weight of 16,600. After cooling to 60 ° C, 175.5 of diethyl N- (3-trimethoxysilylpropyl) aspartic acid ester (prepared according to EP-A 596 360, example 5) is dripped and stirred rapidly until it is no longer visible in the spectrum IR no isocyanate band. The obtained polyurethane prepolymer having alkoxysilyl end groups having a viscosity of 26,000 mPas 23 ° C. A film cast on a glass plate is hardened with catalysis using dibutyl tin diacetate overnight to form a clear, highly flexible plastic with a Shore A hardness of 13. EXAMPLE 2 2000 g of a polyether diol of the OH number of 28 prepared by propoxylation of propylene glycol and subsequent ethoxylation of the prepoxylated product, (proportion PO / EO = 80:20) is prepolymerized with 104.4 g of toluene of 2,4-diisocyanate at 80 ° C until reaching the theoretical NCO content of 0.6%. The polyurethane prepolymer obtained has a calculated average molecular weight of 21,000. After cooling to 60 ° C, 64.6 g of N- (3-trimethoxycylpropyl) aspartic acid dimethyl ester (prepared according to EP-A 596 360, Example 4) are added and stirred until the IR spectrum no longer exists. you see no isocyanate band. The polyurethane prepolymer having alkoxysilyl end groups obtained has a viscosity of 96,000 mPas (23 ° C).A film cast on a glass plate is hardened under catalysis with dibutyltin diacetate overnight to obtain a highly flexible clear plastic of a Shore A- hardness of 8. EXAMPLE 3 4,000 g of polypropylene glycol with an OH number of 14 and with a The degree of unsaturation of 0.005 mEq / m (Acclaim 8200 of the Arc Fa) is prepolymerized with 155.4 g of isophoric diisocyanate at 100 ° C until reaching the theoretical NCO content of 0.4%. The polyurethane prepolymer obtained has a calculated average molecular weight of 21,000. After cooling to 60 ° C, 140.4 g of N- (3-trimethoxysilylpropyl) aspartic acid diethyl ester (prepared according to EP-A 596 360, Example 5) are added and stirred until the IR spectrum no longer exists. you see no isocyanate band. The polyurethane prepolymer having alkoxysilyl end groups obtained has a viscosity of 28,000 mPas (23 ° C). A film cast on a glass plate hardens under catalysis with dibutyltin diacetate in 24 hours to form a flexible plastic with a Shore-A hardness of 15.

EXAMPLE 4 5,300 g of a polypropylene glycol of OH number 10.6 with a degree of unsaturation of 0.005 mEq / g (Acclaim 12200 of the Arc Fa) is prepolymerized with 147.9 g of a commercial mixture containing 80% by weight of toluene 2,4- diisocyanate and 20% by weight of toluene of 2,6-diisocyanate at 80 ° C until reaching the theoretical NCO content of 0.54%. The polyurethane prepolymer obtained has a calculated average molecular weight of 15,500. After cooling to 60 ° C, 226.1 g of N- (3-trimethoxysilylpropyl) aspartic acid dimethyl ester (prepared according to EP-A 596 360, example 4) are dripped and stirred rapidly until it is no longer visible. the IR spectrum no isocyanate band. The obtained polyurethane prepolymer having alkoxysilyl end groups has a viscosity of 25,000 mPas (23 ° C). A film cast on a glass plate hardens under catalysis with dibutyltin diacetate in 24 hours to form a flexible plastic with a Shore-A hardness of 12. EXAMPLE 5 5,300 g of a polypropylene glycol of OH number 10.6 with a degree of unsaturation of 0.005 mAq / g (Acclaim 12,200 of the Arc Fa) is prepolymerized with 166.5 g of isophoric diisocyanate at 100 ° C until the theoretical NCO content of 0.38% is reached. The polyurethane prepolymer obtained has a calculated average molecular weight of 22,000. After cooling to 60 ° C, 175.5 g of diethyl ester of N- (3-trimethoxysilylpropyl) aspartic acid (manufactured according to EP-A 596360 Example 5) are dripped and stirred until the IR spectrum is no longer visible no isocyanate band. The obtained polyurethane prepolymer having alkoxysilyl end groups has a viscosity of 30,000 mPas (23 ° C). A film cast on a glass plate hardens under catalysis with dibutyltin diacetate, in 24 hours to form a flexible plastic with a Shore -A hardness of 12. EXAMPLE 6 Preparation of an isocyanate-free polyurethane sealant: In a commercial planetary mixer , the following components are prepared to obtain a ready-to-use sealant: 41.6 parts by weight Prepolymer of example 3 14.6 parts by weight Phthalate dioisodecyl (plasticizer) 0.20 parts by weight dibutyltin bis-acetoacetonate (10% dissolved in Solvent naphta 100) 1.50 parts by weight trimethoxysilane vinyl 41.6 parts by weight gis filler (Socal type U1S2) The mixture is dispersed for ten minutes at a pressure of 100 m / bar where the internal temperature increases to 60 ° C. Then 0.5 parts by weight of dimethoxysilane of N-aminoethyl-3-aminopropyl-methyl are added and the reaction is carried out at a pressure of 100 m / bar with ten minutes of stirring. The sealant material thus produced shows remarkable stability, adhesion to most substrates and hardens with a skin formation time of approximately 1.5 hours.

It is noted that in relation to this date, the best method known to the applicant to carry out the aforementioned invention, is the conventional one for the manufacture of the objects referred to therein.

Claims (6)

CLAIMS Having described the invention as above, the contents of the following claims are claimed as property:

1. Polyurethane prepolymers having terminal alkoxysilane groups, which are produced by the reaction of: A) linear polyurethane prepolymers which are produced by the reaction of: i) an aromatic, aliphatic or cycloaliphatic diisocyanate component with an NCO content of 20 to 60 % by weight with ii) a polyol component which includes as its main component a polyoxyalkylene diol having a molecular weight of 3000 to 20,000, with B) compounds having alkoxysilane and amino groups of the formula (I) ax in which R and R 'represent the same or different radicals comprising from 1 to 8 carbon atoms, preferably one to 4 carbon atoms and X, Y, Z represent the same or different alkyl or alkoxy radicals of 1 to 4 carbon atoms carbon with the proviso that at least one of the radicals represents a C? -C8 alkoxy group, characterized in that the polyurethane prepolymers A) have an average molecular weight from the NCO content and NCO functionality of 15,000 to 50,000.

2. Polyurethane prepolymers having terminal alkoxysilane groups according to claim 1, characterized in that the polyurethane prepolymers A) have an average molecular weight calculated from the NCO content and the NCO functionality of 20,000 to 40,000.

3. Polyurethane prepolymers having terminal alkoxysilane groups according to claim 1, characterized in that, for the preparation of the polyurethane prepolymers A) polypropylene oxide polyethers with a total degree of unsaturation of a maximum of 0.04 mAq / are used. g and a molecular weight of 8,000 to 20,000 calculated from the OH content and the functionality thereof.

4. Polyurethane prepolymers having terminal alkoxysilane groups according to claim 1, characterized in that X, Y and Z independently represent methoxy or ethoxy. Process for the preparation of polyurethane prepolymers having alkoxysilane groups according to claim 1 to 4 by the reaction of: A) linear polyurethane prepolymers of an average molecular weight calculated from the NCO content and the NCO functionality of 15,000 to 50,000 with B) compounds having alkoxylane groups and amino groups of the formula (I) wherein R and R 'represent the same or different alkyl radicals, with from 1 to 8 carbon atoms, preferably from 1 to 4 carbon atoms and X, Y, Z represent the same or different alkyl or alkoxy radicals from 1 to 4 carbon atoms with the proviso that at least one of the radicals is an alkoxy group, characterized in that the polyurethane prepolymer radicals A) have an average molecular weight calculated from the NCO content and the NCO functionality of 15,000 to 50,000. 6. The use of polyurethane prepolymers having terminal alkoxysilane groups according to claim 1, for the production of low modulus sealing materials. POLYURETHANE PREPOLYMERS COMPRISING GROUPS ALCOXISILANOS TERMINALES, PROCEDURE FOR ITS PREPARATION AND ITS USE FOR THE MANUFACTURE OF SEALANTS. SUMMARY OF THE INVENTION The invention relates to polyurethane prepolymers having terminal alkoxysilane groups based on special high molecular weight polyurethane prepolymers, also to a method for the production thereof and for their use as bonding agents or binders for sealants of low molecular weight.