DE2333567A1 - Alkoxy-silane contg. crosslinkable polymers - useful in moisture-hardening cements, adhesives and coating compsns - Google Patents

Abstract

Prepn. of alkoxysilane gp. contg. cross-linkable prepolymers comprises reacting so-called liquid rubber, which contains double bonds capable of reacting with mercapto gps. and/or contains triple bonds, with silicon cpds. of formula: (where R is an alkyl gp. of 1-18C, R1 and R2 are alkyl gps. of 1-5C, and n = 0, 1 or 2). Pref. the liquid rubber has M.W. 800-80000, esp. 1000-50000. Such rubbers can be polybutadienes of 1,4-, 1,2- and also mixed 1,4- and 1,2-butadienes and also copolymers of butadiene with copolymerisable monomers such as acrylonitrile or styrene. The prepolymers obtd. can be used as raw materials for moisture-hardening cement, sealing compsns. adhesives and coating compsns. where the compsns. can also contain pigments, fillers, catalysts, drying agents, and plasticizers.

Description

"Process for the production of alkoxysilane groups containing polymers "

It is known to prepare prepolymers which have hydrolyzable Alkoxysilane groups are crosslinkable. However, the production of such connections is quite expensive and the conduct of the reaction with regard to compliance with the criteria is quite critical.

It has been found that it is easy to get to via alkoxy * silangi'uppen can get through moisture-crosslinkable polymers, if one of so-called liquid rubbers goes out. The new process is characterized in that double bonds reactive with mercapto groups and / or liquid rubber containing triple bonds with silicon compounds of the general formula

3-n

reacted, where R is an alkyl radical of 1 to 18 carbon atoms and R ¹ and R ^f 'is an alkyl radical of 1 to 5 carbon atoms and η is an integer from 0 to 2.

Liquid polybutadienes, for example, are used as the starting material for the production of the new compounds. It these polybutadienes can vary by 1, ^ -, 1,2- and " mixed 1,4- and 1,2-polymer: isate. Also s: nd

- 2-

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Henkel & Cie GmbH see below

suitable rubber-like copolymers of butadiene and other copolymerizable monomers such as acrylonitrile or styrene. The acrylonitrile content can be between about 15 and 45 % ₃ , but in particular 18-35 % . Finally, so-called saturated rubbers, into which terminal double bonds have been introduced by modification, can also be used as starting material. The molecular weight of the liquid rubbers should be between about 800 and 80,000, in particular 1,000 and 50,000.

The reaction between the double bonds and mercapto groups is known and is catalyzed by basic compounds. Secondary and / or tertiary amines, as well as alkali alcoholates and the like, are used as basic catalysts. Because of the ease of removal it has become practical Reasons the use of volatile amines such as piperidine has proven its worth. The reaction takes place at temperatures between 50 and 180 ° C> in particular 70-140 ° C carried out. It takes about 1/2 to 24 hours, but usually about 2 to 10 hours. The use of organic inert solvents is generally not necessary. But if special highly viscous starting materials are used or the reaction products themselves are highly viscous, it can be expedient be to use organic solvents as diluents.

The silicon compounds containing mercapto groups to be used as starting material must contain at least one alkoxysilane group. It is expedient to start from compounds which are mercaptoalkyl-trialkoxysilanes, in particular those of the mercaptoalkyl- (Cp-C ;,) -trialkoxy- (C ₁ -C 4) SiIaAS type. By varying the amounts of mercaptoalkylalkoxysilane used, based on the so-called liquid rubbers, the properties, in particular with regard to curing, can be largely influenced.

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The polymers which can be prepared according to the invention are crosslinked by formation of siloxanes after hydrolysis of the
Alkoxysilane groups. This hydrolysis is facilitated
by adding catalysts, especially organic tin compounds. This has proven itself, for example
Dibutyltin dilaurate. Of course, the rate of hydrolysis and thus the crosslinking is a given
depends on the temperature and the amount of the catalyst used and can be adjusted accordingly by means of simple experiments.

The prepolymers containing alkoxysilane groups which can be prepared according to the invention can be used as raw materials for moisture-curing putties, sealing compounds, adhesives and
coating agents are used. In this case, additional auxiliaries such as pigments, fillers, catalysts, drying agents, plasticizers and the like will usually be added to the masses.

409884/1236 " ⁶ "

Henkel & CIe GmbH s., T. f * »m .. · ....! * .. ^ ^{/ l} ' ⁷ "' ⁷ AOOOOO /

example 1

108g of liquid polybutadiene (molecular weight approx. 30,000, approx. 50% vinyl groups, based on double bonds) with 5.9g ^ -Mercaptopropyltrimethoxysilan and Ig piperidine were in a dry apparatus, consisting essentially of three-necked flask, stirrer, thermometer and gas inlet tube under a nitrogen atmosphere 80 ° C heated. After five hours, practically all of the silicon compound had been consumed.

After the addition of 1 % dibutyltin dilaurate (10 ^ solution), the product obtained was brushed onto tiles and metal sheets and hardened to form a firm, elastic mass.

Example 2

Using the same starting materials, the reaction was carried out in different amounts. At a reaction temperature of 100 ° C., 19.6 g and 59 g of if-mercaptopropyltrimethoxysilane were used once. The reaction times were 12 and 28 hours, respectively. About 6 % of the silane compound remained unreacted.

After adding dibutyltin dilaurate, a product was obtained which hardened to a solid mass in the air.

Example 3

In an apparatus corresponding to Example 1, 108 g of liquid polybutadiene (molecular weight approx. 3,000, stereospecific ice polymerized) with 19.6g i "-Mercaptopropyl-

409884/1236

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Henker & CIe GmbH "» £ "», «· *« «". D 4747 2333567

trimethoxysilane reacted at 100 ° C. 1% piperidine was used as the catalyst.

After ten hours of reaction, the reaction product still contained about 65% unconverted mercaptosilane. After adding 1 % dibutyltin dilaurate (10 ^ solution) it hardened in the air to a solid mass.

Example 4

248 g of a liquid copolymer of butadiene and acrylonitrile (acrylonitrile content 33 % > molecular weight approx. 1800 to 1900) were reacted with 26.1 g of ufc-mercaptopropyltrimethoxysilane under an anhydrous atmosphere, as described in Example 1. 5 g of piperidine were used as the catalyst. The reaction was practically over after five hours.

The product obtained was admixed with 2% dibutyltin dilaurate (10 # solution) and cured to a solid mass when painted on tiles in the air.

409884/1236

Claims (5)

Henkel & CIe GmbH s., ^ 6 ODQf P ate η ta η s ρ r u c he Process for the preparation of crosslinkable polymers containing alkoxysilane groups, characterized in that that one so-called liquid rubber, the double bonds and / or triple bonds reactive with mercapto groups contains, with silicon compounds of the general formula HS reacted, where R is an alkyl radical of 1 to 18 carbon atoms and R ^f and R ^{tr is} an alkyl radical of 1 to 5 carbon atoms and η is an integer from 0 to 2. 2. The method according to claim 1, characterized in that the liquid rubber has a Molg-sv / icht between 800 and 80,000, in particular 1,000 and 50,000. -7- 4098 84/1236 HENKEL & CIE GMBH see below 7 for ρ «·» * «».! * »« T> ^ 7 ^ 7 2333567 3. The method according to claim 1 and 2, characterized in that the mercapto-containing silicon compound Is mercaptoalkyl trialkoxysilane. k. Process according to Claim 3, characterized in that the compound containing mercapto groups is mercaptoalkyl- (Cp-C _lj ) -trialkoxy- (C ^ -C,) - silane. 5. Use of those producible according to Claims 1 to 4 Connection as moisture-curing putties, Sealing compounds or adhesives, optionally with the addition of customary auxiliaries. 409884/1236 <mz i'D His : · "'")