SU539897A1 - The method of obtaining a porous polymeric material - Google Patents

Description

one

This invention relates to a process for the preparation of styrene-based porous materials. These materials can be used in the production of ion exchange resins and membranes, filters, heat and sound insulating materials. Such porous materials having a controlled structure can be obtained by emulsifying water in the monomer with the formation of a water-in-oil emulsion followed by polymerization of the emulsion in forms. The resulting polymeric materials have a system of communicating channels and pores and, therefore, a huge inner surface.

A method of producing a porous polymeric material suitable for processing into ion exchangers or filters is known by emulsifying water in styrene or its mixture with comonomers and curing the resulting water-in-oil emulsion. The emulsifier is a copolymer prepared by grafting vinyl acetate or alkyl acrylate onto a low molecular weight polyethylene oxide with a molecular weight of at least 500, preferably 1600. The emulsion is cured at a low (room or up to 30 ° C) temperature for a period of 10 hours to 5 days and then after the completion of the polymerization, the water remaining in the polymer is separated by drying under vacuum at 50-90 ° C. After this treatment, a low density porous material is obtained 1.

The known method has several disadvantages. The emulsifier used does not ensure the stability of the emulsion at elevated temperatures, and the polymerization process is too long. In addition, at low temperature, water is not removed from the polymer, and an additional drying step is required to obtain a porous material. Polyethylene oxide based polymers are also expensive.

The purpose of the invention is to eliminate this drawback.

This goal is achieved by using as a polymeric emulsifier 0.5-3% by weight of the monomer or monomer mixture of hydrolyzed ethylene-vinyl acetate copolymer with a degree of hydrolysis of 5-70% and containing 8-20% ethylene.

In order to eliminate these drawbacks, a method is proposed for preparing a porous polymeric material based on styrene by emulsifying water in styrene or its mixture with monomers in the presence of a polymeric emulsifier followed by curing of the emulsion, characterized in that an hydrolyzed ethylene-vinyl acetate copolymer containing 8- 20% ethylene, with a degree

hydrolysis of 5-70% in an amount of from 0.5 to 3% by weight of the monomer.

The water emulsion in styrene, obtained using the specified emulsifier, is resistant to heat - withstands heating for 5-6 hours at 90 ° C. This allows the process to be carried out at a high temperature and thereby accelerates the polymerization process. In addition, there is no need for a separate drying operation of the porous material.

The emulsifier used in the proposed method allows to keep up to 300% of water in the dispersion, however, the introduction of large amounts of water (more than 200%) is not rational, as it leads to a decrease in the mechanical strength of the material.

Hydrolyzed ethylene / vinyl acetate copolymer is relatively cheap.

This method is suitable for the polymerization of styrene or a mixture of styrene with comonomers, such as acrylic and methacrylic.

acids, their esters, maleic anhydride and others copolymerizable with styrene in an amount of 5-25 wt. hours per 100 weight. including styrene.

5 The polymerization process is carried out in the presence of radical-forming initiators, for example, benzoyl peroxide.

The water-in-oil emulsion is cured in forms or in ampoules at 90 °, the reaction time is 5-6 hours.

Example 1. 100 weight. including styrene dissolved 0.5 weight. including a copolymer of ethylene with vinyl acetate (10% ethylene, the degree of hydrolysis of 16%), 0.5 weight. including benzoyl peroxide. 60 vol. In argon flow with continuous shaking. h of water. The hardening of the water in oil emulsion is carried out in ampoules at 90 ° C for 5 hours. A polymer is obtained, dense, with small communicating pores,

0 dry to the touch. Its properties are listed in the table.

Example 2. 100 weight. including styrene dissolve 10. weight. including methyl acrylate, 1 wt. including a copolymer of ethylene with vinyl acetate (16% ethylene, the degree of hydrolysis of 35%), 0.5 weight. including benzoyl peroxide. In a stream of argon with continuous shaking, 200 wt. h of water. Water-in-oil emulsion polymerization is carried out in ampoules at 90 ° C. within 5 hours The polymer is obtained dry to the touch, loose with large interconnecting pores. Its properties are listed in the table.

Example 3. 100 weight. including styrene dissolve 10 weight. including methacrylic acid, 1 wt. including a copolymer of ethylene with vinyl acetate (10% ethylene, the degree of hydrolysis of 20%), 0.5 weight. including benzoyl peroxide. In a stream of argon with continuous shaking, 200 wt. h of water. Water-in-oil emulsion polymerization is carried out in a flat glass form with a distance between walls of 10 mm at 90 ° for 5 hours. A polymer is obtained, loose with large interconnecting pores, dry to the touch. Its properties are presented in the table.

Example 4. 100 weight. including styrene dissolve 25 wt. including methacrylic acid, 1.25 weight. including a copolymer of ethylene with vinyl acetate (8% ethylene, the degree of hydrolysis of 16%), 0.625 weight. including benzoyl peroxide. Is added to

argon flow with continuous shaking 250 wt. h of water. Water-in-oil emulsion polymerization is carried out in the form similar to that used in Example 3 at 90 ° C for 5 hours. A polymer is obtained, dense, with medium communicating pores, dry to the touch. Its properties are presented in the table.

Example 5. Dissolved in 100 wt. including styrene 25 wt. including maleic anhydride, 1.25 weight. including a copolymer of ethylene with vinyl acetate (20% ethylene, the degree of hydrolysis of 70%), 0.875 weight. h. benzoyl peroxide, 2 wt. h

caustic soda. 60 vol. In argon flow with continuous shaking. The polymerization of the water-in-oil emulsion is carried out in the form described in Example 3 at 90 ° C for 5 hours. Get the polymer

dense, with medium communicating pores, dry to the touch. Its properties are listed in the table.

Example 6. 100 weight. including styrene dissolve 10 weight. including methacrylic acid, Zves. h

ethylene-vinyl acetate copolymer (10% ethylene, degree of hydrolysis 5%), 0.5 wt. including benzoyl peroxide. In a stream of argon with continuous shaking, 200 wt. h of water. The water-in-oil emulsion polymerization is carried out in the glass form described

in example 3, at 90 ° C D for 6 hours. The polymer is dense with small interconnecting pores, dry to the touch. Its properties are listed in the table.

Example 7. In 100 weight. including styrene dissolve 5 wt. including methacrylic acid, 3 wt. including a copolymer of ethylene with vinyl acetate (10% ethylene, the degree of hydrolysis of 16%), 0.5 weight. including benzoyl peroxide. In a stream of argon with continuous shaking, 105 wt. including water, in which dissolve 0.2 weight. including potassium persulfate and 0.1 weight. including potassium bicarbonate. Water-in-oil emulsion polymerization is carried out in the form described in Example 3 at 90 ° C for 5 hours. The polymer is a dense, gypsum-filled polymer, with small interconnecting pores. Dry to the touch.

Example 8 (prototype).

A. In 90 weight. including styrene dissolve 5 wt. including emulsifier (vinyl acetate, grafted on polyethylene oxide, having a mol. century 1600). Without air access, 1500 vol. h of water. The emulsion cures at room temperature after 5 days. The cured block contains 90% water; it is dried in a vacuum cabinet at 50--90 ° C.

B. 98 weight. including styrene dissolve 5 wt. including emulsifier (vinyl acetate, grafted on IA copolymer of polyethylene oxide with tetrahydrofuran). Without air access, 150 wt. h of water. The emulsion polymerizes for 10 hours at 30 ° C and at 80 ° C for 48 hours.

Claims (1)

1. US patent No. 3244772, 260-861, 66, (prototype).