JPH039934B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for manufacturing a tubular ion exchange membrane,
In particular, the present invention provides a method for manufacturing a tubular ion exchange membrane that is seamless in the radial and longitudinal directions, has excellent electrical performance, dimensional stability, and mechanical strength, and is suitable as a separation element of a tubular membrane separation module. .

Conventionally, as a method for manufacturing a tubular ion exchange membrane (hereinafter simply referred to as a tubular ion exchange membrane), there is a method for producing a microscopic ion exchange membrane within the pores of a tubular porous membrane, such as that described in U.S. Pat. No. 4,045,332. Method of filling the substance: A so-called heterogeneous membrane method in which thermoplastic resin such as polypropylene or polyethylene and an ion exchange material are dispersed and mixed and formed into a tube shape using an extruder.Ion exchange is carried out in the gap of a double tube structure. 1. A method for forming a tubular membrane by wrapping a sheet-like ion exchange membrane around a support tube and gluing the overlapped portion to form a tubular membrane. However, when actually using the tubular membranes obtained by these methods, there are the following problems. For example, in the method described above, it is necessary to make the particle size of the ion-exchange material to be filled uniform, which not only complicates the manufacturing method, but also makes it difficult to uniformly fill the membrane, which reduces the electrical performance of the resulting tubular ion-exchange membrane. It may be insufficient. In the above method, the operation is complicated due to the need to make the particle size of the ion exchange material uniform, and the performance of the ion exchange material with low heat resistance deteriorates due to the high temperature inside the extruder. If the proportion is too large, the mechanical strength will be weak, and if the proportion is too small, the electrical performance will deteriorate. Since this method does not use a base material, if the thickness of the tubular ion exchange membrane is made thin, for example around 100 to 200μ, the dimensional stability and mechanical strength will be poor, and to compensate for this, the membrane thickness will be increased. This increases the electrical resistance of the resulting tubular ion exchange membrane.
Diffusion coefficient for alkali decreases. With this method, it is difficult to form a uniform membrane due to the difference in the degree of expansion and contraction between the bonded part and other parts of the ion exchange membrane, or there is no suitable adhesive suitable for bonding the ion exchange membrane, and the bonded part is difficult to form. The strength of the tubular ion-exchange membrane is weak, and the functionality of the ion-exchange membrane becomes poor in this area, resulting in a decrease in the effective utilization rate of the tubular ion-exchange membrane.

As a result of intensive studies on the above-mentioned problems, the present inventors have developed a tubular ion-exchange membrane with excellent dimensional stability and mechanical strength by using a braided tube as a base material and polymerizing an ion-exchange membrane on the base material. They found that it can be easily obtained and completed the present invention.

That is, in the present invention, after a braided tube is attached to the outside of a rod-shaped support, an ion exchange group or a monomer having a functional group suitable for introducing an ion exchange group is applied to the surface of the braided tube, and then, after polymerization, , a method for producing a tubular ion exchange membrane, characterized in that the support is desorbed.

The tubular ion exchange membrane obtained by the method of the present invention has dimensional stability, mechanical strength, and flexibility even when the membrane thickness is reduced because the base material (braided tube) is uniformly filled inside the tube. It has excellent electrochemical performance because it has excellent properties and can form a homogeneous ion exchange membrane, and since there are no seams, the entire tube can be effectively used as an ion exchange membrane. Therefore, the tubular ion exchange membrane obtained according to the present invention is suitable as a separation element of a tubular membrane separation module.

The biggest feature of the manufacturing method of the present invention is that a braided tube is used as the base material of the tubular ion exchange membrane, and as mentioned above, it is extremely important to obtain a tubular ion exchange membrane with excellent mechanical strength and dimensional stability. is important. On the other hand, a sheet-like base material is simply attached to a support tube, a monomer mixture such as an ion exchange group or a monomer having a functional group suitable for introduction into the ion exchange group is applied thereto, and then polymerization is performed. In this method, it is inevitable that the sheet-like substrates overlap, and the strength of the overlapped portion is weak, and the thickness of the membrane differs between the overlapped portion and other portions, making it impossible to produce a uniform tubular ion exchange membrane. The term "braided tube" in this specification is a general term for seamless tubular knitting, and by using a known knitting machine, for example, the knitting needles of the knitting machine are arranged in a cylindrical shape to produce flat knitting, rubber knitting, purl knitting, etc. It can be obtained by weaving it into a tubular shape using the following method. The base material constituting such a braided tube is selected in consideration of affinity with ion exchange resin, chemical stability, thermal stability, dimensional stability, etc., such as glass,
Various organic or inorganic fibers such as polyvinyl chloride, polyethylene terephthalate, polypropylene, vinylidene-vinyl copolymer, etc. are used, and among them, polyvinyl chloride is preferably used. The thickness of the single fiber used for these is proportional to the thickness of the tubular membrane, so it can be selected appropriately depending on the thickness of the desired ion exchange membrane.
~200 deniers are preferably used. In addition, if the size of the mesh of the above-mentioned braided tube is too large, the mechanical strength of the tubular ion exchange membrane obtained will decrease and it will be prone to cracking, so it is preferable to make it as small as possible, and generally 20 to 100 gauge. degree is preferred. Further, the diameter of the braided tube may be appropriately selected depending on the diameter of the intended tubular membrane, and is generally about 0.1 mm to 50 mm.

The rod-shaped support used in the present invention may be made of any material and have a shape that can support the above-mentioned braided tube, and the support may be made of a material with excellent heat resistance and monomer resistance, such as glass or Teflon. used. Further, the cross-sectional shape of the support is not particularly limited,
Although it is appropriately selected depending on the shape of the tubular ion exchange membrane, it is generally a tubular shape that is slightly smaller than a braided tube.

One sequence of the manufacturing method of the present invention will be explained with reference to FIG. Finally, the braided tube 3 is attached to one or more rod-shaped supports 2, (2' and 2'') provided on the support stand 1.

The braided tube can be attached to a rod-shaped support by, for example, inserting a rod-shaped support with a diameter approximately the same as the inner diameter of the braided tube so as to be inscribed in the braided tube, and then sealing by tying the upper and lower braided tubes together. Methods such as this will be adopted.

Thereafter, a monomer mixture 4 such as an ion exchange group or a monomer having a functional group suitable for introducing an ion exchange group is applied to the surface of the braided tube, and after polymerization, the above-mentioned support is desorbed. In addition, when introducing an anionic group or a cationic exchange group after coating the monomer mixture described above and then polymerizing, it should be carried out after the support is desorbed after the polymerization, or it can be carried out as it is without desorbing the support. Any method of introducing an ion exchange group and then desorbing the support may be used. The monomer mixture is not particularly limited, and any known composition for producing an ion exchange membrane may be used as appropriate. For example a) Monomers having ion exchange groups or functional groups suitable for the introduction of ion exchange groups; for example amide or ester derivatives of styrene, styrene sulfonic acid and vinyl sulfonic acid, vinyl pyridine and its derivatives, maleic anhydride, methyl vinyl ketone; b) divinylbenzene as a crosslinking agent c) a monomer copolymerizable with a) and b) above;
For example, styrene, acrylonitrile, maleic anhydride, acrylic ester, methacrylic ester, etc. d) Other substances that do not become members of the ion exchange resin structure after polymerization; for example, polyvinyl chloride fine powder,
Plasticizers such as dioctyl phthalate and dibutyl phthalate, solvents for diluting monomers,
Linear polymeric substances soluble in the monomer mixture of a) to c) (polystyrene, polybutadiene,
Natural rubber, etc.) etc. e) Ordinary radical polymerization catalyst At least a), b) of the above a) to e),
There are solutions or pastes containing e). A method of applying such a monomer mixture to the surface of a braided tube is, for example, by placing the monomer mixture in a container that is such that the braided tube is inscribed when the braided tube is inserted, and after inserting the braided tube into the container. , how to seal the top,
Alternatively, there is a method in which the braided tube is immersed in a container filled with a monomer mixture, the monomer mixture is applied to the surface of the braided tube, the tube is taken out from the container, and the monomer surface is completely covered with a film. The container into which the above-mentioned braided tube is inserted is made of glass or aluminum, and the film used is heat-resistant and monomer-resistant, such as cellophane, vinylon film, or vinyl alcohol, to prevent dissipation of the monomer. Helps prevent. These are removed after polymerization. Polymerization is carried out under known conditions, for example, at a temperature of 40 to 120°C for about 30 minutes to 24 hours. In addition, methods for converting the base membrane obtained by polymerization into an ion exchange membrane include conventionally known methods such as sulfonation, chloromethylation, amination, quaternary ammonium basicization, quaternary pyridinium basicization, and hydrolysis. This can be carried out as appropriate depending on the functional groups in the membrane.

Examples of the present invention will be shown below.

Example 1 A glass tube (outer diameter 10 mm) was used as a support, a braided tube of polyvinyl chloride fiber (single yarn thickness 50 denier, gauge number 32, flat knit) was attached to the outer surface of the glass tube, and then styrene was attached. 95 parts, divinylbenzene 5 parts,
A paste in which 100 parts of fine polyvinyl chloride powder, 25 parts of dioctyl phthalate, and 1.5 parts of benzoyl peroxide are uniformly dispersed is applied to the surface of the braided tube.
The outer surface is covered with cellophane, heated and polymerized at 100°C for 4 hours, and the film-like material obtained by removing the cellophane on the outer surface is treated in 98% sulfuric acid at 60°C for 10 hours.

The thickness of the obtained tubular membrane was 250 μm, and the dimensional stability was good, and a uniform membrane without cracks or pinballs was obtained. The properties of the ion exchange membrane obtained in this example are as follows: burst strength: 2.5 Kg/cm ² resistance: 4 Ω/cm ² , ring ratio: 0.92
It was hot.

Example 2 A braided tube similar to Example 1 was attached to a glass tube,
100 parts of styrene, 84 parts of methylvinylpyridine, 10 parts of divinylbenzene, 200 parts of polyvinyl chloride powder
A monomer mixture consisting of 1 part, 6 parts of benzoyl peroxide, and 60 parts of dioctyl phthalate was applied to the braided tube, the outer surface was covered with cellophane paper, and the base membrane was polymerized by heating at 110°C. This was quaternized with methyl iodide to obtain an anion exchange membrane. The properties of the ion exchange membrane obtained in this example were a burst strength of 4 kg/cm ² , a resistance of 4.5 Ω/cm ² and a ring ratio of 0.91.

Comparative Example 1 The same glass tube as in Example 1 was inserted into the double tube structure without using a braided tube, and the same monomer as in Example 1 was filled into the gap, and then polymerized under the same conditions as in Example 1. A tubular membrane was obtained.

The thickness of the obtained tubular membrane was 250 μm, but the bursting strength was 0.2 Kg/cm ² and both mechanical strength and dimensional stability were low.

Comparative Example 2 Teviron cloth (trade name) with a width of 40 mm was wrapped around the same glass tube as in Example 1 in a spiral shape so that the width of the overlapping part was 10 mm, and after immersing it in the same monomer as in Example 1, it was taken out and the outer surface was It was covered with cellophane and polymerization and sulfonation was carried out under the same conditions as in Example 1.

The bursting strength of the tubular membrane obtained was weak at 0.3 Kg/cm ² and the overlapping portion peeled off. Furthermore, since the film thickness was different between the overlapping part and the non-overlapping part, a straight film could not be obtained.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing an example of the method of the present invention. In the figure, 1 is a support, 2 is a rod-shaped support, 3 is a braided tube,
4 is a monomer mixture.

Claims (1)

[Claims] 1 After attaching the braided tube to the outside of the rod-shaped support,
Production of a tubular ion exchange membrane, characterized in that an ion exchange group or a monomer having a functional group suitable for introduction of an ion exchange group is applied to the surface of the braided tube, and after polymerization, the support is desorbed. Method.