JPS6142304A - Removal method - Google Patents

Abstract

PURPOSE:To provide hydrophilized polyolefin excellent in safety and operability, by forming a cellulose acetate membrane to the surfaces of the fibriles forming a porous polyolefin hollow yarn. CONSTITUTION:A porous polyethylene hollow yarn, wherein fine voids formed by a large number of fibriles communicate the inner and outer wall surfaces of the hollow yarn, is prepared. This porous polyethylene hollow yarn is impregnated with a cellulose acetate-containing solution and subsequently immersed in a coagulant solution of cellulose acetate and rapid wet coagulation is performed to form a cellulose acetate film to the surfaces of fibrils. The hollow yarn module using thus obtained hydrophilic porous polyolefin hollow yarn is not lowered in a filtering speed even after filtering is interrupted to contact said hollow yarn with air and can repeat filtering with stable reliability.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to porous polyolefin hollow fibers with excellent hydrophilicity.

[Prior art]

Various membranes are known as ultrafiltration membranes and precision filtration membranes used for producing pure water, filtering colloidal substances in water, and the like.

In particular, membranes for medical, pharmaceutical, food, and precision industries are required to remove bacteria, and in particular, membranes that can also remove pyrogens are required for medical and pharmaceutical applications. . Although many membranes that can remove bacteria are known, there are no ultrafiltration membranes or microfiltration membranes that can simultaneously remove pyrogens.

Reverse osmosis is a well-known method that can also remove pyrogens, but because reverse osmosis requires high pressure, equipment costs are high, the equipment is large, and salmon quality cannot be satisfied unless the processing volume is increased. Not only is this difficult, but the method involves storing treated water and using it little by little as needed.

Even if various measures are taken to store water, there is a drawback that bacteria and pyrogens can contaminate the treated water.

In particular, porous membranes for water treatment, which have minute pores that can block bacteria, must be hydrophilic to allow water to pass through them.
Membranes made of hydrophilic materials tend to deteriorate when attacked by microorganisms, and there is a problem in that the concentration of bacteria increases on the side where the membranes are attacked.

Previously, in Japanese Patent Publication No. 56-52123 and Japanese Patent Application Laid-Open No. 57-42919, the present applicant solved the drawbacks of conventional devices, and developed a system with low equipment and energy costs, a simple structure, and fewer failures. As a highly reliable membrane for precision filtration equipment, we proposed a porous polyolefin hollow fiber in which micropores with a pore diameter Q of 0.1 to 1 μm communicate between the inner and outer wall surfaces of the hollow fiber. However, since this is a hydrophobic porous polyolefin hollow fiber, it is used by temporarily making it hydrophilic with alcohol etc. before use and replacing it with water. If the surface of the porous polyolefin hollow fiber is removed and dried by contacting with air, there is a problem that the freeness decreases, and there has been a strong demand for the development of a porous polyolefin hollow fiber with excellent hydrophilicity.

[Problem that the invention seeks to solve]

An object of the present invention is to provide a hydrophilized porous polyolefin hollow fiber that is safe and has excellent operability. The micropores formed between many arranged fibrils are
A porous polyolefin hollow fiber that communicates between the inner wall surface and the outer wall surface of the hollow fiber, the hydrophilic porous material having a t% characteristic that a film made of cellulose acetate is formed on the surface of the fibril. ℃ achieved by polyolefin hollow fibers.

A porous polyolefin hollow fiber in which micropores formed by a large number of fibrils communicate between the inner wall surface and the outer wall surface of the hollow fiber can be produced, for example, according to the above-mentioned Japanese Patent Application Laid-Open No. 57-42919. As a method for obtaining permanently hydrophilic porous polyethylene hollow fibers by forming cellulose acetate membranes on the surfaces of fibrils forming such porous polyethylene hollow fibers, for example, a solution containing cellulose acetate is made into a porous polyethylene hollow fiber. After impregnating polyethylene hollow fibers, a method can be used in which a cellulose acetate film is formed on the surface of the fibril by immersing it in a coagulant solution of the cellulose acetate and performing a rapid wet coagulation treatment.

In this case, any cellulose acetate used in the present invention can be used as long as it has film-forming ability. It is preferable that the cellulose acetate be fixed as uniformly as possible on the surface of the fibrils, and that the amount of the cellulose acetate should be kept to a minimum, so as to minimize the clogging of the pores of the hollow fibers due to the fixation treatment. Cellulose acetate membranes exhibit excellent hydrophilic properties. Therefore, a porous polyolefin hollow fiber in which a cellulose acetate membrane is adhered to the fibril surface exhibits excellent hydrophilicity. It is sufficient to apply the general known module manufacturing method using threads as is, and as long as liquid or gas is filtered from the outer wall side of the porous hollow fibers to the inner wall side, or from the inner wall side to the outer wall side, Any form of module may be used. By using the hydrophilized porous polyolefin hollow fiber of the present invention, it is possible to remove colloidal substances, A1Ms, and pyrogenic substances, and while maintaining safe operability at all times, equipment costs and energy costs are lower than conventional equipment. The structure is simple, there are few failures, and it enables highly reliable precision filtration.

〔Example〕

Hereinafter, the present invention will be explained with reference to Examples.〇 One porous polyethylene hollow fiber (Mitsubishi Rayon Co., Ltd. ) made,
After dipping in EHF (trade name), the solution was squeezed to make the amount of solution attached to the hollow fibers 310% owf, and then immersed in water at 60°C to remove the solvent by rapid coagulation of cellulose acetate, and then stack the hollow fibers. A porous polyethylene hollow fiber with a thin film of cellulose acetate fixed to the structural surface was obtained. 100 of these hydrophilized porous polyethylene hollow fibers were bundled in a U-shape and the openings of the hollow fibers were solidified with resin to create a module with a resin-embedded portion of 4 cm in length and a hollow fiber effective length of 10α.

After filling the inside of this module with ethanol at 25°C and impregnating the inside of the porous polyethylene hollow fiber with ethanol, 5 tons of water was applied to the outer wall of the hollow fiber at a pressure of 380 mHf. After bringing the fiber outer wall into contact with air, a pressure of 680■Hf is applied from the hollow fiber outer wall again.
When exposed to water, no change was observed in f overspeed before and after contact with air.

Comparative Example 1 A normal module was prepared in the same manner as in Example 1 using the above-mentioned porous polyethylene hollow fibers that had not been subjected to the hydrophilic treatment, and water was passed through the module, water was drained, and water was passed through the module again. The filtration rate of this module decreased by 32 cm after contact with air.

〔Effect of the invention〕

The hollow fiber module using the hydrophilic porous polyolefin hollow fibers of the present invention is capable of repeating filtration with stable reliability without decreasing the filtration rate even after filtration is interrupted and the hollow fibers are brought into contact with air. I can do it.

Claims (1)

[Claims] 1. A porous polyolefin hollow fiber in which micropores formed between a large number of fibrils arranged substantially in the longitudinal direction of the hollow fiber communicate between the inner wall surface and the outer wall surface of the hollow fiber. , a hydrophilized porous polyolefin hollow fiber characterized in that a membrane made of cellulose acetate is formed on the surface of the fibrils.