CS243586B1 - Method of 3-methacryloxypropylsilanes' aqueous solutions preparation - Google Patents

Abstract

The invention describes catalyzed hydrolysis 3-methacryloxypropyltrialkoxysilanes in water in the presence of emulsifiers. It uses methacrylic acid as a catalyst or acrylic. Prepared aqueous solutions silanes are particularly suitable for treatment glass fibers for reinforcing polyesters.

Description

The invention relates to a process for the preparation of aqueous solutions of 3-methacryloxypropylsilanols by hydrolysis of 1-C 4 -C 2 alkoxypropyltrialkoxysilanes in water in the presence of acidic catalysts and optionally emulsifiers.

Substituted trialkoxysilanes have found a wide and continually expanding application application for the treatment of fillers, especially glass fibers used as reinforcement for various compositions.

Industrially, the most widely used method is to apply these compounds from aqueous systems, mainly because the use of organic solvents is limited, either because of their toxicity, flammability and, last but not least, for economic reasons. Especially for these reasons, the greatest attention is paid to the preparation of aqueous silane compositions.

Methacryloxypropyltrialkoxysilanes are known and their synthesis and use as well as hydrolysis have been described as early as 1967 Ε. P. Pleueddemann and HA Clark (U.S. Pat. No. 3,258,477). These silanes are water-insoluble but become soluble when alkoxy groups hydrolyze. The hydrophobic moiety of 3-methacryloxypropylsilanols is in equilibrium with the hydrophilic, i.e., they form a strong oriented layer at the water-air interface, resulting in a significant reduction in the surface tension of the water.

Usually formic, acetic and propionic acid are used as catalyst (Noll W .: Chemie und Technologie der Silikone, Verlag Chemie 1968). It is also known to use citric acid as a catalyst followed by extraction of silanol from water with a non-polar solvent (French Patent No. 2,139,097). In addition to these catalysts, organic titanium compounds (NSR Pat. No. 1,495,418), ion-exchangers (U.S. Ser. No. 183,491), dihydrophosphates (U.S. Ser. No. 212,015) are used.

The acceleration of hydrolysis can be achieved by the addition of various emulsifiers to form a fine silane emulsion in water, thereby increasing the silane-water-catalyst surface area (British Patent No. 1,009,908). Because aqueous solutions of these compounds are stably constrained, particular care has been taken to prepare their stable solutions (EP Pat. No. 0 049 365), usually by separating the catalysts (U.S. Pat. No. 4,395,563).

The catalysts used in these processes are primarily intended to accelerate the hydrolysis process.

The invention describes a process for the preparation of aqueous solutions of 3-methacryloxypropylsilanes by hydrolysis of 3-methacryloxypropyltrialkoxysilanes having 1 to 3 carbon atoms in the alkoxy group in water in the presence of acid catalysts and optionally emulsifiers. The invention is based on the fact that methacrylic acid or acrylic acid in a weight ratio of silane:

: acid, 1: 0.005 to 2.

The hydrolysis can be carried out in various devices equipped with agitators, mixers, colloid mills and the like. In the case of using low speed stirrer devices or devices with limited mixing circulation, it is possible to achieve an even distribution of the silane emulsion by adding to the water various emulsifiers which reduce the surface tension of the water.

The silane hydrolysates according to the invention serve mainly for the surface treatment of glass fibers. Drying of the treated fibers, which is generally carried out at a temperature of 120 to 130 ° C, results in polymerization in situ to form a copolymer film. In this way, the stiffness of the glass fibers, which is necessary for their processing by chopping, is increased. At the same time, the adhesion of the polymers used to coat glass fibers is improved. The presence of carboxyl groups causes increased surface polarity, which has a positive effect on the antistatic properties, properties and wettability of glass fibers by polar plastics. In contrast to the known catalysts, the catalysts according to the invention are also actively involved in modifying the surface properties of glass fibers.

The invention is further illustrated by way of examples.

Example 1

Methacrylic acid was dissolved in 500 ml of water and 10 g of 3-methacryloxypropyltrimethoxysilane was added with stirring. The amount of acid and its effect on the course of hydrolysis in minutes are shown in Table 1.

Table 1 acid (gj Hydrolysis (min)

0,5 55

22

7

5

Example 2

1 g of nonylphenol oxyethylated with 9 moles of ethylene oxide and 2 g of acrylic acid were dissolved in 500 ml of water. 10 g of 3-methacryloxypropyltrimethoxysilane are added while stirring. Hydrolysis was performed in 8 minutes. Example 3

2 g of methacrylic acid were dissolved in 500 ml of water and 10 g of 3-methacryloxypropyl-tris- (2-methoxyethoxy) silane was added with stirring. Hydrolysis was performed in 10 minutes. Example 4

The aqueous silanol solution prepared according to Example 2 was mixed with 600 g of a 500% polyvinyl acetate dispersion, 15 g of lithium chloride, 25 g of a 12.5% amineamide-based lubricant and made up to 5,000 ml with water. The composition thus prepared is suitable for treating glass fibers to reinforce unsaturated polyester resins.

Claims (2)

SUBJECT A process for the preparation of aqueous solutions of 3-methacryloxypropylsilanols by hydrolysis of 1-to-3-carbon-3-methacryloxypropyltrialkoxysilanes in water in the presence of acid catalysts, in the present invention and emulsifiers, characterized in that the catalyst used is methacrylic acid or acrylic acid , 1: 0.05 to 2.