JPS5952165B2 - Method for manufacturing cation exchange resin - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a cation exchange resin having sulfonic acid groups with fewer cracks.

Conventionally, as a method for producing cation exchange resins having sulfonic acid groups, a monovinyl aromatic monomer such as styrene and a polyvinyl aromatic monomer such as divinylpenzene are copolymerized to obtain a crosslinked polymer, and then this crosslinked polymer is copolymerized. The combined product is swollen with a swelling agent such as benzene or tetrachloroethane in an amount of 10 to 50% by weight, and then sulfonated with a sulfonating agent such as sulfuric acid or fuming sulfuric acid to obtain a reaction mixture. The method used is to add water to hydrate. In this method, the sulfonating agent is diluted by the water generated during sulfonation of the crosslinked polymer, so sulfonation is usually performed using about 6 times the theoretical amount of the sulfonating agent, and after the reaction is completed, the sulfonating agent is diluted with water. is added for hydration, and then processed through processes such as washing with water to become a product. In this case, since a large amount of the sulfonating agent is used as described above, the heat generated during hydration causes cracks in the sulfonated crosslinked polymer. Also,
There is a problem in processing the large amount of diluted sulfonating agent (diluted sulfuric acid) discharged through the above process. The present inventor has conducted various studies with the aim of industrially advantageously producing a cation exchange resin having a sulfonic acid group of excellent quality using a small amount of sulfonating agent. It has been found that this objective can be achieved by using small amounts of sulfonating agent in the medium and carrying out the sulfonation under specific conditions.

That is, the gist of the present invention is to sulfonate a crosslinked polymer under boiling conditions using a sulfonating agent in a liquid chlorinated carbonaceous medium with a boiling point of 130° C. or less, and to remove the water produced in the reaction system. A cation exchange resin having a sulfonic acid group, characterized in that only the chlorinated hydrocarbon layer is distilled off together with the chlorinated hydrocarbon, and the distillate is allowed to stand and separated, and then recycled to the reaction system. It consists in the manufacturing method.

The present invention will be explained in detail below.

As the crosslinked polymer applied to the present invention, those commonly used as a base material for cation exchange resins having sulfonic acid groups can be used.

For example, d obtained by copolymerizing monovinyl aromatic compounds such as styrene, methylstyrene, vinyltoluene, and vinylethylbenzene with polyvinyl aromatic compounds such as divinylbenzene, divinyltoluene, divinylethylbenzene, divinylxylene, and divinylnaphthalene. ,
Examples include spherical crosslinked copolymers. In addition, during this polymerization reaction, a so-called porous material is produced by allowing a linear polymer, a solvent, etc. to coexist in the polymerization reaction system, and removing these linear polymers, solvent, etc. from the polymer particles after the reaction. Polymer crosslinked copolymers can also be used in some cases.

The chlorinated hydrocarbon used in the present invention has a boiling point of 1
Examples include those that are liquid at room temperature of 30°C or lower, specifically, for example, 1,3-dichloropropane, 1,1,2-
Trichloroethane, 1,2-dichloropropane, 1,2
- Dichloroethane etc. are used.

In addition, the amount used should be slightly in excess of the amount sufficient to swell the crosslinked polymer, and although it can be used in a significantly large amount, it is not economical, so it is usually 1 to 3 liters per crosslinked polymer.
Approximately double the amount (capacity) is appropriate. Examples of the sulfonating agent include concentrated sulfuric acid or fuming sulfuric acid, which are commonly used, and are preferably used in a stoichiometric amount to a slight excess, and if used in large quantities, the advantages of the present invention will not be achieved.

Usually, the theoretical amount or more is about 1.3 times the amount (0.9 to 1.2 times the weight of sulfuric acid based on the weight of the crosslinked polymer is preferable.The theoretical amount of the sulfonating agent referred to as Vc here means It means the amount (as SO3) equivalent to the amount (number of moles) of the monovinyl aromatic compound (for example, styrene) used in the production of.

To explain the method of the present invention in more detail, predetermined amounts of the chlorinated hydrocarbon medium and the crosslinked polymer are mixed and heated under stirring to
After the crosslinked polymer is partially swollen with chlorinated hydrocarbon at a temperature of 70°C, a sulfonating agent is gradually added and heated under atmospheric pressure, and sulfonation is carried out under boiling conditions with stirring, and the chlorinated hydrocarbon and Distill water. At this time, the temperature is 130
It is preferable to choose a type of chlorinated hydrocarbon that can be maintained at temperatures below about 0.9°C. The distillate is cooled with a suitable cooler and left for a while to separate into two layers, the chlorinated hydrocarbon layer and the chlorinated hydrocarbon layer. A stable reaction can be maintained in the presence of an amount of chlorinated hydrocarbon medium. The reaction is thus continued for an appropriate period of time, for example 8 to 20 hours, depending on the conditions, to complete the sulfonation reaction. When carrying out the above-mentioned sulfonation reaction, the crosslinked polymer tends to aggregate into lumps as the reaction progresses, and uniform sulfonation tends to be inhibited.

Therefore, during sulfonation, it is preferable to add a surfactant in advance or a substance that forms a surfactant by the action of the sulfonating agent in the reaction system. The surfactant may be one that is stable under the reaction conditions in the presence of the sulfonating agent, such as alkylaryl sulfonic acid, sulfonated fatty acid ester, olefin sulfonic acid, higher alcohol sulfate ester, sulfated oil, etc. be able to.

Also, as a surfactant precursor, depending on the sulfonating agent present. Substances that are sulfonated or sulfated to produce surfactants, such as dodecylbenzene,
Tridecylbenzene, stearic acid, palmitic acid, lauric acid, methyl stearate, methyl palmitate,
hexadecene, octadecene, stearyl alcohol,
Examples include lauryl alcohol and castor oil. The amount of the fruit surface active agent or its precursor added is approximately 0.5 to 3.0% by weight based on the crosslinked polymer. After the sulfonation reaction, the reaction mixture is cooled and then hydrated by adding water. Hydration must be carried out as slowly as possible in order to prevent cracking of the resin, and for this reason, it is necessary to pay attention to, for example, the rate and method of adding water. After completion of hydration, the sulfonated crosslinked polymer is separated from the medium, neutralized with aqueous alkaline solution, residual chlorinated hydrocarbons are removed by steam distillation, then washed with water, and if necessary, hypochlorous acid is added. It is commercialized as a cation exchange resin having sulfonic acid groups by bleaching with sodium or the like.

According to the method of the present invention, the use of a specific chlorinated hydrocarbon medium and a small amount of sulfonating agent and the distillation of water and medium in the sulfonation reaction result in less sulfonating agent remaining in the finished reaction mixture and further reducing the sulfonating agent. The hydration in the chlorinated hydrocarbon medium in the reaction mixture is particularly easy, combined with the low residual sulfonating agent mentioned above, and generates less heat during hydration and produces fewer cracks. A cation exchange resin having groups can be obtained.

Furthermore, since the amount of waste acid discharged according to the present invention is extremely small, there is no problem in terms of environmental protection. Next, the present invention will be explained with reference to examples, but the present invention is not limited to the following examples.

In the examples shown below, parts mean parts by weight. Examples 1 to 10 (a) Production of crosslinked polymer The raw materials shown in Table 1 (styrene-ethylvinylbenzene, divinylbenzene and polystyrene) and 0.7 parts of benzoyl peroxide were mixed with 0.1% polyvinyl alcohol. 8 parts of water with stirring in a nitrogen atmosphere.
Suspension polymerization was carried out at 0°C for 8 hours.

The obtained polymer particles were thoroughly washed with water and then dried. In addition, for crosslinked polymer numbers 4, 5 and 6, after the above water washing, further 5
00 parts of benzene was added, and the mixture was heated and stirred at 80° C. for 6 hours to extract and remove polystyrene, and then dried under reduced pressure.

(b) Sulfonation reaction The raw materials and reaction conditions are shown in Table 2.

Add the above (
The crosslinked polymer produced by method a), the surfactant listed in Table 2, and the chlorinated hydrocarbon medium were each charged in the prescribed amounts shown in Table 2, stirred gently at about 65°C for 1 hour, and then Cool to room temperature.

Next, a predetermined amount of the sulfonating agent shown in Table 2 was injected over a period of about 5 hours, the medium was boiled according to the conditions shown in Table 2, water was distilled out along with the medium, and the distillate was left to stand after cooling. The reaction was carried out for a predetermined period of time while circulating the medium layer separated into two layers through the reaction system. Next, the reaction product was cooled with water, the rotation speed of the stirring blade was set to about 500 rpm, and a glass filter (G-1) V
Approximately 2 c below the surface of the reaction mixture! Water is gradually added through the glass filter at a rate of addition and cooling such that the temperature of the reaction mixture remains below about 30°C. Next, after neutralizing with an aqueous solution of about 10N sodium hydroxide, the sulfonated crosslinked polymer is sent from house to house. Approximately 250% of this sulfonated crosslinked polymer! ! 1 t of water is added, and the remaining chlorinated hydrocarbon medium is distilled off by steam distillation, and after cooling, it is washed with water to obtain a cation exchange resin having sulfonic acid groups. As shown in Table 2, the cation exchange resin having sulfonic acid groups obtained in this example has a high exchange capacity and almost no cracks, even though a small amount of the sulfonating agent was used. In other words, it had a high appearance index.

Claims (1)

[Claims] 1. A crosslinked polymer is sulfonated using a sulfonating agent under boiling conditions in a liquid chlorinated hydrocarbon medium with a boiling point of 130°C or less, and the water produced in the reaction system is chlorinated. A method for producing a cation exchange resin having a sulfonic acid group, characterized in that the chlorinated hydrocarbon layer is distilled off together with hydrocarbons, the distillate is allowed to stand and separated, and only the chlorinated hydrocarbon layer is separated and recycled to the reaction system. . 2. The method for producing a cation exchange resin having a sulfonic acid group according to claim 1, which uses a surfactant or its precursor during sulfonation. 3. The method for producing a cation exchange resin having a sulfonic acid group according to claim 1, wherein the crosslinked polymer is a crosslinked polymer obtained by copolymerizing a monovinyl aromatic compound and a polyvinyl aromatic compound.