JPH0553529B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to composite membrane materials. More specifically, the present invention relates to a composite membrane material that is excellent in film formability, strength, operability, etc. and can be effectively used as a separation membrane.

[Conventional technology]

Chemical industry for the purpose of removing impurities and producing pure water,
Separation membranes used in the food industry, electronics industry, etc. have conventionally been manufactured by, for example, a solvent volatilization method or an underwater gelation method. However, if the membrane thickness is made thinner in order to improve the separation membrane performance, the membrane loses its strength and therefore becomes less operable. Furthermore, since a carrier such as a glass plate is required during film formation, the process is complicated in terms of operation, such as a step of peeling the film from the carrier.

Furthermore, since fiber materials have a large total surface area, they are used, for example, as carriers for immobilized enzymes and deodorants, and when used for such purposes,
Furthermore, it is desirable to increase the total surface area.
One way to increase the total surface area is to make the fibrous material itself porous, but making the fibrous material itself porous leads to a decrease in the physical strength of the fibrous material itself, so it is not a preferable method. .

[Problem that the invention seeks to solve]

In view of the above circumstances, the present inventors have conducted repeated studies to obtain a porous membrane material that is excellent in film formability, strength, operability, etc. form a film,
It has been found that such problems can be effectively solved by using a composite membrane material for separation membranes.

[Means for solving problems]

Accordingly, the present invention relates to a composite membrane material for a separation membrane, which comprises a polyvinyl butyral porous membrane formed on a support.

As the support, quantitative or qualitative paper, fiber materials such as various fibers or non-woven fabrics thereof, and filter materials such as glass filters and ceramic filters are used.

Formation of polyvinyl butyral films on these supports can be carried out by adding up to about 25% by weight of polyvinyl butyral to an organic solvent such as methylene chloride, acetone, methyl ethyl ketone, or ethanol, preferably about
This is carried out by preparing a dope solution dissolved at a concentration of 10% by weight or less, applying it onto a support by means such as dipping, spraying, spreading, etc., and leaving it in an atmosphere at room temperature to about 80°C.

At this time, when a dope solution with a concentration of about 10% by weight or less is dried in an atmosphere with a relative humidity (RH) of about 30% or more, a porous film with many micropores is formed on the support. be done. This is because the latent heat during evaporation of the solvent used to form the dope solution lowers the temperature of the coated surface, and moisture in the air condenses there, causing the polyvinyl butyral to become porous during gelation. It is considered that

〔Effect of the invention〕

By forming a porous film of polyvinyl butyral on a support such as a textile material,
The total surface area of the surface layer can be increased without reducing the physical strength of the fibrous material or the like.

Specifically, a composite membrane material that can be used as a separation membrane can be formed, and can be effectively used for concentrating fruit juice, recovering colloidal latex, etc., and capturing microorganisms.

〔Example〕

Next, the present invention will be explained with reference to examples.

Example 1 Polyvinyl butyral (Wako Pure Chemical Industries, Ltd.) was dissolved in methylene chloride to prepare a dope solution having a concentration of 1% by weight. This dope solution was spread on one side of qualitative paper (No. 1 manufactured by Toyo Roshi) under conditions of 27° C. and 83% RH and left for one day.

The separation membrane thus obtained was attached to a batch-type membrane evaluation cell (Toyo Roshi UHP-43).
A pressure of 2 kg/cm ² was applied with nitrogen gas, and the water permeability and separation rate of Saccharomyces cerevisiae (yeast) were determined (the concentration of the yeast aqueous solution was 0.1 g/cm2, and the concentration was checked using a spectrophotometer at a wavelength of 600 nm).
) were measured respectively. As a result, a value of 2.5/cm ² ·atm ·hr was obtained for water permeability, and a value of 100% for yeast separation rate.

Examples 2 to 4 Polyvinyl butyral (Wako Pure Chemical Industries, Ltd.) was dissolved in methylene chloride, acetone or methyl ketone to prepare a dope solution having a concentration of 3% by weight. A polyamide fiber Tegus (Toray Miran Tegus Ginrin No. 1 manufactured by Toray Industries, fiber diameter 0.165 mm) was immersed in this dope solution, pulled up, and left in air at 27° C. and 60% RH for 10 minutes.

When the coatings thus formed on the surface of the polyamide fibers were observed using SEM photographs, it was confirmed that the coatings were all porous membranes having many micropores of around 0.1 μm in size. All of the formed surface porous membranes were well adhered to the polyamide fiber fibers, and did not peel off due to bending or scratching with nails.

Example 5 In Example 2 using methylene chloride, ordinary rayon (manufactured by Daiwabo Co., Ltd., fineness 1.5 denier) was used instead of the polyamide fiber TEGUS. It was confirmed that a porous film having countless micropores was formed on the surface of ordinary rayon.

Claims (1)

[Claims] 1. A composite membrane material for separation membranes comprising a polyvinyl butyral porous membrane formed on a support.