JPS58194925A - Production of porous membrane - Google Patents

Abstract

PURPOSE:To produce a porous membrane of a uniform pore diameter, by irradiating a polymer membrane with charged particles accelerated by an accelerator and then etching the membrane. CONSTITUTION:A polymer membrane (e.g., polycarbonate membrane) is irradiated with charged particles accelerated by an ion accelerator and then immersed in an etchant such as NaOH or HNO3 to dissolve the part damaged by the impinging particles and form a porous membrane of a uniform pore diameter. EFFECT:The irradiation energy of charged particles can easily be adjusted according to the thickness of a polymer membrane. This process is applicable to polymer membranes of various thicknesses, and the size of pores can be controlled by changing the kind of ions emitted from an accelerator.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a porous membrane in which pores of uniform pore size are formed in a polymer membrane. The purpose is to easily change the energy of charged particles to be irradiated accordingly.

Normally, porous polymer materials are widely used in various industrial fields to medical fields, and there are various types of materials ranging from microporous materials with pore diameters of nm to porous materials of about 500 μm. These pore sizes are used in a wide variety of fields.

There are three main methods for producing conventional porous membranes.

One of them is a method of bonding particles chemically or thermally, and is called a sintering method.

The other method is to fill the pores with an inorganic or organic substance that is soluble in water or a solvent before molding.
This is a method of obtaining a porous body by eluting the molded and reconstituted material, and is called a salt elution method or a solvent volatilization method.

Yet another method is to mechanically or chemically create holes in a polymer film, which are called a stretching method and a radiation irradiation method, respectively.

By the way, the porous film obtained by the above method has radiation #! With the exception of the irradiation method, all methods have pores with uneven pore sizes and complex sponge-like shapes, making it impossible to perform highly selective filtration of fine particles.

On the other hand, the radiation irradiation method is a method in which a polycarbonate membrane is irradiated with fission fragments produced by a nuclear fission reaction and chemically etched to obtain a porous membrane.The pores formed in the membrane are linear in shape and have uniform pore diameters. It has characteristics different from porous membranes obtained by other methods. but,
Because nuclear fission fragments from a nuclear reactor are used, there are significant restrictions on its use and it is dangerous, so it is not a simple irradiation source.Furthermore, the energy of the irradiated particles is fixed and distributed. Therefore, it cannot be applied to thick films.

This invention was made with the above points in mind,
A method of porosity characterized in that a polymer membrane is irradiated with charged particles accelerated from the 11th beam, and after the irradiation, the polymer membrane is etched to form pores with uniform pore diameters in the polymer membrane. This is a method for manufacturing a membrane.

Therefore, since an accelerator is used, the charged particles generated are of high energy.Furthermore, since the accelerator is a mechanical radiation source, the generation of charged particles cannot be stopped immediately if the power is cut off. It is extremely easy to handle, has no restrictions or dangers like when using a conventional nuclear reactor, and can significantly downsize and simplify JR manufacturing equipment. Furthermore, the irradiation method is P, which allows uniform irradiation by scanning a charged particle beam. Furthermore, the energy of the charged particles to be irradiated can be easily changed depending on the thickness of the polymer film to be irradiated, so that it can be applied to polymer films of various thicknesses.

Further, the size of the hole 1 can be controlled by changing the type of ions taken out from the accelerator.

In addition, the accelerator is a high-frequency radial type ion source,
Duo plasmatron type, electronic vibration type.

Any ion accelerator using a sputter type or the like can be used.

Furthermore, any charged particles may be used as long as they have energy that can penetrate the irradiated polymer membrane.

Furthermore, as a polymer membrane, polycarbonate is used.

Polyethylene terephthalate, cellulose nitrate.

61 cellulose, vinylidene fluoride, polytetrafluoroene, polyacrylonitrile, etc. can be used.

'1゜In addition, as an etching agent, any solvent capable of eluting areas damaged by incident particles may be used, such as sodium hydroxide, an alkaline solution of dichromic acid (IJ4), or an acidic solution such as nitric acid or sulfuric acid. Next, an example of the method for manufacturing a porous membrane of the present invention will be described.Example 1 After irradiating a polycarbonate membrane with a thickness of 10 μm with nitrogen ions at an ionic current of 180 fiA accelerated by an accelerator,
It was etched by immersing it in a 6N sodium hydroxide solution at 60°C, washed with water, and then dried in the air. The pore size and pore density were observed using a scanning electron microscope. As a result, the pore size was uniform, 1 μm, and the pore density was 2×106j. It was a solid/crA porous membrane.

Example 2 After irradiating IJium ions with an ion current of 5 onA accelerated by a polyethylene terephthalate film accelerator with a thickness of 12 μm, etching was performed by immersing in a 6N sodium hydroxide solution at 60°C, then washing with water and air drying. However, as a result of observation with a scanning electron microscope, it was found to be a porous membrane with a uniform pore diameter of 0.6 μm and a pore density of 1 × 106/crjl. After irradiation with helium ions with an accelerated ion current of 180 pA, it was etched by immersion in a 6N sodium hydroxide solution at 40°C, washed with water, dried in the air, and observed with a scanning electron microscope. Uniform pore diameter of ゜μm,
It was a porous membrane with a pore density of 4 x 10' a/ca.

Example 4 A polyvinylidene fluoride film with a thickness of 9 μm was irradiated with helium ions of 80 VIA of ions accelerated by an accelerator, etched by immersion in a 6N sodium hydroxide solution at 60°C, washed with water, and then exposed to air. The film was dried in a vacuum chamber and observed under a scanning electron microscope. As a result, it was found to be a porous film with a uniform pore diameter of 0.1 μm and a pore density of I x 10'/CI.

Representative Patent Attorney Ryuta Fujita

Claims (1)

[Claims] (2) A porous membrane characterized in that a polymer membrane is irradiated with charged particles accelerated by an accelerator, and after the irradiation, the polymer membrane is etched to form pores with uniform pore diameters in the polymer membrane. #! How to send.