JPH0534046B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field] The present invention relates to a method for removing colloidal substances, bacteria, or pyrogenic substances in water using 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 and filtering colloidal substances in water. 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 known as a method that can also remove heat-generating substances, but because reverse osmosis requires high pressure, equipment costs are high, the equipment is large, and it is difficult to satisfy economic efficiency unless the throughput is increased. In addition, it is possible to store treated water and use 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, cannot pass through water unless they are hydrophilic. However, membranes made of hydrophilic materials tend to deteriorate when attacked by microorganisms, and they also block bacteria. The problem is that the bacterial concentration increases on the side where the bacteria is exposed.

First, in Japanese Patent Publication No. 56-52123 and Japanese Patent Application Laid-open No. 57-42919, the applicant solved the drawbacks of conventional devices, and developed a device that has low equipment costs and energy costs, is simple in structure, has few failures, and As a highly reliable membrane for precision filtration equipment, we proposed a porous polyolefin in which micropores with a pore diameter of 0.01 to 1 μm communicate between the inner and outer walls of hollow fibers. 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 to be solved]

An object of the present invention is to provide a method for removing colloidal substances, bacteria, or pyrogenic substances in water using hydrophilized porous polyolefin hollow fibers that are safe and have excellent operability.

[Means to solve]

The above object of the present invention is to provide a porous polyolefin in which micropores formed between a large number of fibrils arranged substantially in the longitudinal direction of the hollow fibers communicate between the inner wall surface and the outer wall surface of the hollow fibers. A porous polyolefin hollow fiber having a membrane made of acrylonitrile or polyurethane resin formed on the surface of the fibril of the hollow fiber is impregnated with ethanol to make it hydrophilic, and then the water is filtered. This is achieved by a method for removing colloidal substances, bacteria or pyrogenic substances from water.

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 is disclosed in the above-mentioned Japanese Patent Application Laid-Open No. 57-42919.
It can be manufactured by No. As a method for obtaining permanently hydrophilic porous polyethylene hollow fibers by forming an acrylonitrile-based or polyurethane-based resin film on the surface of the fibrils that form such porous polyethylene hollow fibers, there is a method for obtaining a permanently hydrophilized porous polyethylene hollow fiber. After adhering a solution containing resins to the surface of porous polyethylene hollow fibrils, these resins are immersed in a coagulant solution and subjected to rapid wet coagulation to form an acrylonitrile or polyurethane resin film. can be formed and firmly attached to the surface of fibrils. In this case, when forming a porous acrylonitrile membrane, the acrylonitrile resin used should be a polymer containing 30% by weight or more of acrylonitrile.If a polymer with an acrylonitrile content of less than 30% by weight is used, the acrylonitrile resin will be This is not preferable because it reduces hydrophilicity. Acrylonitrile resin is an acrylonitrile homopolymer or acrylonitrile and
Copolymers with vinyl acetate, methyl acrylate, methyl methacrylate, vinyl chloride, acrylamide, etc. are preferably used.

When forming a polyurethane resin film, known materials may be used, such as aliphatic polyethers having hydroxyl groups, carboxy groups, etc. and active hydrogen at the terminals, or condensation polymers of polyesters and diisocyanates. .

These acrylonitrile-based or polyurethane-based resin films should be adhered as uniformly as possible to the surface of the fibrils of the porous hollow fibers, and the amount of adhesion should be kept to a minimum to minimize clogging of the open pores of the hollow fibers due to adhesion treatment. is preferred.

Acrylonitrile-based films and polyurethane-based films exhibit excellent hydrophilicity. Therefore, a porous polyolefin hollow fiber having an acrylonitrile or polyurethane membrane adhered to the surface of the fibril exhibits excellent hydrophilicity.

In order to manufacture a module using the hydrophilic porous polyolefin hollow fiber of the present invention, it is sufficient to apply the general known module manufacturing method using porous hollow fiber as it is, from the outer wall side of the porous hollow fiber to the inner wall side. Any form of module may be used as long as it filters liquid or gas from the side or from the inner wall to the outer wall. By using the hydrophilic porous polyolefin hollow fiber of the present invention, it is possible to remove colloidal substances, bacteria, 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.

Example 1 93% by weight of acrylonitrile and 7% by weight of vinyl acetate
A porous polyethylene hollow fiber (manufactured by Mitsubishi Rayon Co., Ltd., trade name: EHF) was immersed in a solution at 25°C in which 1 part by weight of a powdery acrylonitrile copolymer consisting of 1 part by weight was dissolved in 99 parts by weight of dimethylformamide. After squeezing the solution, reduce the amount of solution attached to the hollow fiber to 80% owf.
The fibers were then immersed in hot water at 60°C to make the acrylonitrile copolymer porous by rapid coagulation and to remove the solvent, and then thoroughly washed with water and dried to form hollow fiber fibrils. An acrylonitrile-based membrane was formed on the surface of the fiber to obtain a hydrophilized porous polyethylene hollow fiber.

100 of these hydrophilized porous polyethylene hollow fibers were bundled into a U-shape, and the openings for the hollow fibers were hardened with resin.
A module having a resin-embedded part length of 4 cm and a hollow fiber effective length of 10 cm is preferably used.

Ethanol at 25°C was introduced from the outside of the hydrophilized porous polyethylene hollow fiber to impregnate the inside of the porous polyethylene hollow fiber, and then the water in step 5 was filtered from the outside of the hollow fiber under a pressure of 380 mmHg. After removing the water and leaving the outside of the hollow fiber in contact with air for 5 hours, the outside of the hollow fiber was again exposed to a pressure of 380°C.
As a result of water filtration under mmHg, no change was observed in the filtration rate of the module using the hydrophilized porous polyethylene hollow fibers of the present invention.

Comparative Example 1 A normal module was prepared in the same manner as in Example 1 using the porous polyethylene hollow fibers that had not been subjected to the hydrophilic treatment, and a filtration experiment was conducted in the same manner as in Example 1. A module using this end-treated porous polyethylene hollow fiber had a 32% decrease in filtration rate after 5 hours of contact with air.

Example 2 4 parts to 100 parts by weight of polyester (molecular weight 1500) synthesized from adipic acid and 1-4 butanediol
29 parts by weight of -4' diphenylmethane diisocyanate was added and reacted for 3 hours at 80°C under a nitrogen stream to obtain polyurethane. 0.5 parts by weight of this polyurethane was dissolved in 99.5 parts by weight of dimethylformamide at 25°C.
The same porous polyethylene hollow fiber as used in Example 1 was immersed in the same solution as that used in Example 1, and the solution was squeezed to make the amount of solution attached to the hollow fiber 330% owf. After performing porosity through rapid solidification treatment and solvent removal treatment, the fibers were sufficiently washed with water and dried to obtain hydrophilized porous polyethylene hollow fibers with a polyurethane membrane fixed to the surface of the fibrils of the hollow fibers. 100 of these hydrophilized porous polyethylene hollow fibers were bundled in a U-shape, the opening for the hollow fibers was hardened with resin, and the length of the resin-embedded part was 4 cm.
A module with a hollow fiber effective length of 10 cm was created.

After pouring ethanol at 25°C from the outside of the hydrophilized porous polyethylene hollow fiber to impregnate the inside of the porous polyethylene hollow fiber, the water in step 5 was filtered from the outside of the hollow fiber under a pressure of 380 mmHg. , after removing the water and leaving the outside of the hollow fiber in contact with air for 5 hours, a pressure of 380°C was applied from the outside of the hollow fiber.
No change in filtration rate was observed when water was filtered under mmHg.

Comparative Example 2 A normal module was prepared in the same manner as in Example 2 using porous polyethylene hollow fibers that had not been subjected to hydrophilic treatment in the same manner as in Comparative Example 1. The filtration rate of the module using this untreated porous polyethylene hollow fiber decreased by 32% after 5 hours of contact with air.

〔Effect of the invention〕

The method for removing colloidal substances, bacteria, or pyrogenic substances in water using a hollow fiber module using the hydrophilic porous polyolefin hollow fibers of the present invention can be applied even after filtration is interrupted and the hollow fibers are brought into contact with air. Filtration can be repeated with stable reliability without reducing the filtration rate.

Claims (1)

[Claims] 1. Micropores formed between a large number of fibrils arranged approximately in the longitudinal direction of the hollow fiber are formed on the fibril surface of the porous polyolefin hollow fiber, which communicates between the inner wall surface and the outer wall surface of the hollow fiber. , a colloidal substance in water characterized by filtering water after making it hydrophilic by impregnating the inside of porous polyolefin hollow fibers in which a membrane made of acrylonitrile or polyurethane resin is formed, with ethanol, and bacteria. or how to remove pyrogenic substances.