Oraganocarbonate-modified prepolymer, its use as a reactant for the preparation of isocyanate-free and isothiocyanate-free alkoxysilane polymers, and compositions thereof

Abstract

The use of an organocarbonate-modified prepolymer having at least an average of 1.5 carbonate, thiocarbonate, carbamate or thiocarbamate groups bonded directly to the polymer backbone each via an oxygen atom, where each of these oxygen atoms has its origin in the reaction of a primary, secondary or tertiary hydroxyl group of the polymer backbone and a reactive compound selected from the group consisting of a diorganocarbonate, a diorganothiocarbonate, a cyclic carbonate, a cyclic thiocarbonate, an N,N-diheterocyclourea derivative and an N,N-diheterocyclothiourea derivative. Also, the preparation of the alkoxysilane polymers.

Claims

1. A process for preparing an alkoxysilane polymer comprising: reacting a prepolymer comprising, at least on average, 1.5 carbonate groups of the formulae (I) and (II), 1.5 thiocarbonate groups of the formulae (Ia) and (IIa), 1.5 carbamate groups of the formulae (XI) and (XII), or 1.5 thiocarbamate groups of the formulae (XIa) and (XIIa) ##STR00017## in which R.sup.1 and R.sup.2 independently of one another are linear or branched C.sub.1 to C.sub.6 alkyl, C.sub.1 to C.sub.6 acyl, C.sub.3 to C.sub.8 cycloaliphatic, C.sub.6 to C.sub.10 aryl or imide radicals or C.sub.3 to C.sub.6 alcohols, R.sup.11 and R.sup.12 and also R.sup.13 and R.sup.14 in each case together form heterocyclic ring systems which may be aromatic or nonaromatic and are independent of one another, and wherein these ring systems may contain further heteroatoms selected from the group of oxygen, nitrogen, and sulfur or may contain functional groups selected from the group of acyl and thioacyl, wherein the at least on average 1.5 carbonate, thiocarbonate, carbamate or thiocarbamate groups are bonded directly via one oxygen atom each to the polymer backbone of the prepolymer, this one oxygen atom each having its origin in the reaction of a primary, secondary or tertiary hydroxyl group of the polymer backbone and a reactive compound selected from the group consisting of a diorganocarbonate, a diorganothiocarbonate, a cyclic carbonate, a cyclic thiocarbonate, an N,N-diheterocyclourea derivative, and an N,N-diheterocyclothiourea derivative with: (A) an aminoalkoxysilane or a mercaptoalkoxysilane, optionally in the presence of a catalyst, or (B) a diamine, a triamine, a dithiol or a trithiol to give a modified prepolymer and subsequently carrying out reaction with an alkoxysilane compound comprising an epoxide group, to form the alkoxysilane polymer.

2. The process as claimed in claim 1, wherein, before the reaction with (A) or (B), the prepolymer is reacted with an alcohol or with an activated alcohol.

3. The process as claimed in claim 1, wherein the aminoalkoxysilane in (A) is selected from the group of 3-aminopropyltrimethoxysilane, 3-aminopropyltriethoxysilane, N-(n-butyl)-3-aminopropyltrimethoxysilane, N-(n-butyl)-3-aminopropylmethyldimethoxysilane, N-(n-butyl)-3-aminopropyltriethoxysilane, N-ethylaminoisobutyltrimethoxysilane, N-ethylaminoisobutylmethyldimethoxysilane, 3-piperazinopropyltrimethoxysilane, 3-piperazinopropylmethyldimethoxysilane, 3-piperazinopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropyltrimethoxysilane, N-(2-aminoethyl)-3-aminopropyltriethoxysilane, N-(2-aminoethyl)-3-aminopropylmethyldimethoxysilane, and an equimolar reaction product of piperazine and glycidoxypropyltrimethoxysilane, and the mercaptoalkoxysilane is selected from the group of 3-mercaptopropyltrimethoxysilane, 3-mercaptopropyltriethoxysilane, 3-mercaptopropylmethyldimethoxysilane and 3-mercaptopropyltrimethoxysilane.

Description

EXAMPLE 1

Methyl Carbonate-Terminated Polyether with Aminosilane

(1) 95.7 g of polyether diol (Desmophen 4028BD from Covestro) are refluxed at 120° C. for 18 h with 17.3 g of dimethyl carbonate (4:1 based on OH groups) and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The methanol formed and the excess of dimethyl carbonate can be subsequently distilled off under reduced pressure. The product obtained is methyl carbonate-terminated polyether.

(2) ##STR00015##

(3) 50 g of the methyl carbonate-terminated polymer are reacted with 4.3 g of 3-aminopropyltrimethoxysilane and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 60° C. for 24 h. The methanol formed is removed by distillation. The product obtained is trimethoxysilane-terminated polyether. The trimethoxysilane groups are joined to the polyether via a urethane bond.

(4) ##STR00016##

(5) The polymer can be used for producing moisture-curing adhesives, sealants, and coating materials on the basis of silane-terminated polymers.

EXAMPLE 2

Methyl Carbonate-Terminated Polyether with a Diamine, Subsequent Reaction with Epoxysilane

(6) 95.7 g of polyether diol (Desmophen 4028BD from Covestro) are refluxed at 120° C. for 18 h with 17.3 g of dimethyl carbonate (4:1 based on OH groups) and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The methanol formed and the excess of dimethyl carbonate can be subsequently distilled off under reduced pressure. The product obtained is methyl carbonate-terminated polyether. 50 g of the methyl carbonate-terminated polymer are reacted with 2.84 g of hexamethylenediamine and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD) at 60° C. for 24 h. The methanol formed is removed by distillation. The product obtained is an amine-terminated polyether. This polyether can be reacted with an alkoxysilane compound having an epoxide group, as for example (3-glycidyloxypropyl)trimethoxysilane, to form a trimethoxysilane-terminated polyether. Such reactions are described in detail in European patent application EP-A-2 341 116, hereby referenced.

(7) The resulting polymer can be used for producing moisture-curing adhesives, sealants, and coating materials on the basis of silane-terminated polymers.

EXAMPLE 3

Curing of a Methyl Carbonate-Terminated Polyether to form an Isocyanate-Free Polyurethane

(8) 95.7 g of polyether diol (Desmophen 4028BD from Covestro) are refluxed at 120° C. for 18 h with 17.3 g of dimethyl carbonate (4:1 based on OH groups) and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD). The methanol formed and the excess of dimethyl carbonate can be subsequently distilled off under reduced pressure. The product obtained is methyl carbonate-terminated polyether.

(9) 50 g of the methyl carbonate-terminated polymer are mixed with 1.42 g of hexamethylenediamine and 0.1 g of 1,5,7-triazabicyclo[4.4.0]dec-5-ene (TBD), optionally in a solvent or in water, in the presence of auxiliaries such as stabilizers and emulsifiers at 90° C. for 24 h. The molar mass of the polyether-polyurethane can be influenced by the auxiliaries and reaction conditions. The resulting dispersion can subsequently be used, for example, for polyurethane dispersion-based adhesives.

EXAMPLE 4

Imidazole Carbamate-Terminated Polyether with Aminosilane

(10) 95.5 g of polyether diol (Desmophen 4028BD from Covestro) are stirred under nitrogen at 60° C. for 12 h with 7.76 g of 1,1′-carbonyldiimidazole (CDI) (1:1 based on OH groups). The product obtained is imidazole carbamate-terminated polyether.

(11) 50 g of the imidazole carbamate-terminated polymer are reacted with 4.3 g of 3-aminopropyltrimethoxysilane at 60° C. for 24 h. The product obtained is trimethoxysilane-terminated polyether. The trimethoxysilane groups are joined to the polyether via a urethane bond.

(12) The resulting trimethoxysilane-terminated polymer can be catalyzed without tin and crosslinks following addition of 0.2% of 1,8-diazabicyclo[5.4.0]undec-7-ene and 1% of 3-aminopropyltrimethoxysilane, under atmosphere moisture, to form an elastic material having a Shore A hardness of 41 after 7 days.