JPS6214162B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for producing an insoluble cation exchanger having sulfonic acid groups. Currently, insoluble cation exchangers with sulfonic acid groups based on polymonovinyl aromatic compounds are superior to those based on other polymers in terms of exchange capacity, chemical resistance, heat resistance, etc. It has been industrialized in the form of granular resins and membranes. Granular powder resins are used for various purposes such as the production of pure water and ultrapure water, nuclear power, and acid catalysts, and membranes are used for separation of useful substances, desalination, etc. Recently, fibers have been used in the production of ultrapure water, nuclear power, acid catalysts, ion exchange filter paper, and the adsorption and desorption of ionic high molecular weight substances because they have a large surface area, can be given various shapes, and are easy to clean. It is attracting attention as a new material. Powdered or granular resins are produced by copolymerizing a monovinyl aromatic compound and a polyvinyl aromatic compound as a crosslinking agent to make the compound crosslinked and insolubilized, followed by sulfonation. On the other hand, it is difficult to make membranes and fibers, especially fibers, into a fiber shape after crosslinking and insolubilizing a polymonovinyl aromatic compound, so a method of insolubilizing by introducing a crosslinking group in the fiber state and then sulfonation is recommended. It has been proposed (Special Publication No. 56-8046). However, in the latter case, it is necessary to perform a two-step reaction treatment of crosslinking reaction and sulfonation reaction.
Disadvantages include that coloration tends to occur, and that operations are complicated and manufacturing costs are high. On the other hand, in the former case, an expensive polyvinyl aromatic compound must be used as a crosslinking agent, and the sulfonation reaction must be carried out at high temperature for a long time, which causes bond splitting, coloring, etc. due to side reactions. There are drawbacks,
For example, in applications where the purity of the treatment liquid is required, the resin itself must be sufficiently washed and purified. The present inventors have arrived at the present invention as a result of intensive studies aimed at improving these manufacturing defects. That is, the present invention involves a reaction treatment of a polymonovinyl aromatic compound molded article in 93 wt% or more sulfuric acid containing 0.05 to 3 wt% formaldehyde source to form a crosslinking group and 0.25 mol or more per 1 mol of aromatic nucleus of the compound. This invention relates to a method for producing a cation exchanger having a water content of 0.5 to 10, characterized in that a sulfonic acid group is simultaneously introduced. The object of the present invention is to add -CH ₂ - or - to a polymonovinyl aromatic compound molded product.
(CH ₂ O) _o Hydrous containing a crosslinking group represented by CH ₂ - with excellent chemical resistance and heat resistance, and a sulfonic acid group of 0.25 mol or more, particularly 0.5 mol or more, per mol of aromatic nucleus of the polymonovinyl aromatic compound. degree 0.5~20, especially 1~
An object of the present invention is to provide a method for easily and inexpensively producing a cation exchanger of 10 with high purity. By adopting a composition consisting of a specific concentration of sulfuric acid containing a specific concentration of a formaldehyde source, the present inventor surprisingly introduced the crosslinking group and the sulfonic acid group simultaneously with almost no dissolution of the polymer. For the first time, I discovered what was possible. The method of the present invention is a rational reaction treatment in one step at a relatively low temperature and in a short time compared to the two-step method,
Moreover, it has the characteristics of having few side reactions, easy cleaning and purification, and low manufacturing cost.
Furthermore, by adjusting the amount of the formaldehyde source, it is possible to adjust the amount of the formaldehyde source depending on the purpose, for example, from a high water content type suitable for adsorption/desorption of high molecular weight substances to a type suitable for catalysts, ultrapure water production, and nuclear power related applications. It can be manufactured freely even with low water content. The present invention will be explained in detail below. The polymonovinyl aromatic compound molded product referred to in the present invention is a molded product of the polymonovinyl aromatic compound (A) alone, or a mixture with a reinforcing polymer (B) that is substantially inert and has a mechanical strength-maintaining effect, or It means a molded product of a composite, and specific examples of molded products include powders, granules, membranes, fibers, hollow fibers, porous bodies thereof, and highly processed products thereof. As described above, the method of the present invention is rational and economical for producing membranes and fibers, and is particularly suitable for producing fibers. In the case of membranes and fibers, it is preferable to contain a reinforcing polymer in order to maintain their shape. For example, specific examples of such fibers include a simple mixed fiber of the above A and B, a fiber with A as the main component of the sheath component, and a fiber with B as the main component of the sheath component. A core-sheath type composite fiber having A as a core component and a multicore sea-island type composite fiber having A as a main component of a sea component and B as an island component can be mentioned. In this case, the proportion of reinforcing polymer B is preferably 70% or less from a functional standpoint. Examples of the form of such fibers include filament yarns, cut fibers, punched felts, woven fabrics, knitted fabrics, nonwoven fabrics, fiber bundles, knitted cords, braided cords, stuffed cotton, paper, and cut products thereof. The polymonovinyl aromatic compound referred to in the present invention refers to a homopolymer of a monovinyl monomer having an aromatic group represented by styrene, α-methylstyrene, vinyltoluene, vinylxylene, vinylnaphthalene, etc., or a copolymer of two or more of these monomers. It means a copolymer or a graft polymer with other inert monomers, or a blend thereof, and polystyrene and polyα-methylstyrene are particularly preferably used. As the reinforcing polymer (B), polyolefin having excellent chemical resistance is preferably used. As the polyolefin, polypropylene, polyethylene, poly-3-methylbutene-1, poly-4-methylpentene-1, etc. are preferably used. The concentration of sulfuric acid constituting the present invention is usually 93 wt% or more, but if the concentration is too low, not only will the amount of sulfonic acid groups introduced decrease, but the sulfonation rate will decrease, and the reaction will have to be carried out at high temperatures for a long time. The content is preferably 94 wt % or more, as this may cause side reactions or a decrease in the mechanical strength of the molded product. Also, the concentration of the formaldehyde source of the present invention is usually
The concentration is preferably 0.05 to 3 wt%, but if the concentration is too low, the polymer will partially dissolve, and if it is too high, the coloring of the reactants and reaction solution will increase, and the sulfonation rate will decrease, so it is preferably 0.1 ~1wt% is preferred. The formaldehyde source used in the present invention refers to a formaldehyde derivative that generates formaldehyde by the action of formaldehyde and sulfuric acid, and formaldehyde is blown into the reaction solution as a gas and dissolved, or paraformaldehyde, trioxane, tetraoxane, methylaldehyde, etc. It may also be supplied in the form of methylene diacetate or the like. In particular, paraformaldehyde is preferably used for operational reasons and preparation of the reaction solution. Incidentally, if necessary, silver sulfate or the like may be added to the sulfuric acid as a reaction catalyst. In the reaction of the present invention, the higher the temperature, the higher the amount of sulfonic acid groups introduced and the higher the sulfonation rate. However, if the temperature is too high, side reactions may occur or the strength of the molded product will decrease, so a temperature range of 20 to 110°C is usually preferred. , preferably 50
-100°C, particularly preferably 60-90°C. The reaction time depends on the type of polymonovinyl aromatic compound, the size and shape of the molded product, the sulfuric acid concentration, the formaldehyde source concentration, the reaction temperature, etc., but it is usually carried out in the range of 0.5 to 20 hours, especially 1 to 6 hours. . The amount of reaction liquid is sufficient as long as the molded product is immersed, for example, it is usually 3 to 200 parts for 1 part of the molded product, but if it is too small, the reaction will be uneven, and if it is too large, the reaction tank will become too large. 5 to 100 parts is preferable since it is not economical to use too much. Examples are shown below, but the invention is not limited thereto. Examples 1 to 4, Comparative Example 1 Multicore sea-island composite fiber (undrawn yarn) [sea component (polystyrene polypropylene)/island component (polypropylene) = (474))/49 (number of islands 16, fiber diameter
34μ)] was cut to a length of 1 mm to obtain a cut fiber. 1 part of the cut fiber was mixed with commercially available primary sulfuric acid,
The mixture was added to 14 parts of a reaction solution in which the sulfuric acid concentration and formaldehyde source concentration were adjusted using paraformaldehyde and water, and the mixture was reacted at 80° C. for 4 hours, followed by washing with water. Table 1 shows the water content and cation exchange capacity of the cation exchangers obtained for various reaction solutions. Table 3 also shows the amount of sulfonic acid group introduced. Here, moisture content refers to Na-type cation exchange fibers that are soaked in distilled water, centrifugally dehydrated for 5 minutes using a home-use centrifugal dehydrator to remove surface moisture, and immediately measured by weight (W).
The value was obtained from the following formula by measuring the weight, drying it completely, and then weighing it (W ₀ ). Water content = (W-W ₀ )/W ₀ From Tables 1 and 3, it can be seen that when the sulfuric acid concentration is less than 93 wt% (Comparative Example 1), the amount of sulfonic acid groups introduced (exchange capacity) is extremely small. Examples 5 to 9, Comparative Examples 2 to 4 The multicore sea-island composite fiber of Example 1 was drawn 4.5 times (fiber diameter 16μ), doubled to 240 denier, and then wound around 16 bobbins. , using a stringing machine
We made 3840 denier braid. One part of the braid was added to 28 parts of a reaction solution in which the sulfuric acid concentration and formaldehyde source concentration were adjusted using commercially available primary sulfuric acid and paraformaldehyde, followed by reaction treatment at 80°C for 2 hours, followed by washing with water. Table 2 shows the water content and cation exchange capacity of the cation exchangers obtained for various reaction solutions.

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[Table] Amount of group introduced When no formaldehyde source was present in the reaction solution (Comparative Example 2), polystyrene was sulfonated and dissolved, leaving only polypropylene as a reinforcing polymer. If the formaldehyde source concentration in the reaction solution is too low, only a small portion of polystyrene will dissolve (Comparative Example 3), and if it is too high, the amount of sulfonic acid groups introduced (exchange capacity) will be small, resulting in coloring of the reactants and reaction solution. (Comparative Example 4). Example 10 Grind polystyrene lentils with a coffee mill,
It was separated using a wire mesh filter to obtain an amorphous powder of 150 to 280μ. One part of the powder was prepared by the method of Example 9 and contained 0.36 wt% formaldehyde source.
It was added to 14 parts of a 96.1 wt % sulfuric acid solution, reacted at 80°C for 4 hours, and washed with water. The water content of the obtained cation exchanger was 5.1, the cation exchange capacity was 4.0meq/g,
The amount of sulfonic acid group introduced was 0.7 mol. Example 11 The performance of the cation exchangers obtained in Examples 2, 4, and 8 above was investigated. The cation exchanger of Example 2 was applied to the adsorption and desorption of alkaline protease, the exchanger of Example 4 was applied to the production of pure water, and the H-type exchanger of Example 8 was applied as a hydrolysis catalyst for methyl acetate. All of them showed good results, and showed performance comparable to that of conventional products manufactured in two steps of crosslinking reaction and sulfonation reaction.

Claims (1)

[Claims] 1 Polymonovinyl aromatic compound molded products from 0.05
A water content of 0.5 characterized by simultaneously introducing a crosslinking group and 0.25 mole or more of sulfonic acid group per mole of aromatic nucleus of the compound by reaction treatment in 93 wt% or more sulfuric acid containing 3 wt% formaldehyde source. ~Ten
A method for producing a cation exchanger.