JPS6222802A - Dispersant for emulsion polymerization - Google Patents

Abstract

PURPOSE:The titled dispersant which can improve the dispersibility of a vinyl monomer and give a polymer emulsion in a stable emulsified state, comprising a maleic acid (anhydride)/styrenesulfonate copolymer. CONSTITUTION:A maleic acid (anhydride)/styrene copolymer obtained by reacting 1mol of maleic acid (anhydride) with 1-5mol of styrene in the presence of a catalyst such as benzoyl peroxide or lauryl peroxide is sulfonated and then subjected to liming and sodation to obtain a dispersant for emulsion polymerization comprising a maleic acid (anhydride)/styrenesulfonate copolymer of a number-average MW of 500-200,000.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to a dispersant for emulsion polymerization, and more particularly, it is used in emulsion polymerization of vinyl monomers to improve the dispersibility of the monomers, The present invention also relates to a dispersant for emulsion polymerization that can produce a polymer emulsion in a stable emulsified state.

[Prior Art] The emulsion polymerization method is heavily used as a method for polymerizing vinyl monomers such as vinyl acetate and vinyl chloride. In this polymerization method, the reaction proceeds using water as a medium, so when polymerizing water-insoluble substances such as the above-mentioned vinyl monomer, a dispersant for emulsion polymerization is added together with the monomer, polymerization initiator, and surfactant in water. It is common to improve the dispersibility of nanatsumer by adding it.

As such a dispersant for emulsion polymerization, an alkali neutralized product of a maleic anhydride-isobutylene copolymer is conventionally known.

[Problems to be Solved by the Invention] However, when this product is used to carry out the emulsion polymerization of the vinyl monomer described above, the dispersibility of the seven polymers in water is not very good, so the polymerization reaction cannot be carried out smoothly. There was a problem that the process did not proceed and furthermore, the stability of the obtained polymerized emulsion was low.

The present invention solves such conventional problems, and is particularly applicable to the emulsion polymerization reaction of vinyl monomers to improve the dispersibility of the monomers in water, and furthermore to improve the stability of the resulting polymerized emulsion. The purpose of the present invention is to provide a dispersant for emulsion polymerization that is capable of

[Means for Solving the Problems] As a result of extensive research in order to solve the above object, the present inventors found that conventional isobutylene was used as one of the copolymer components in the copolymer constituting the dispersant.

The present invention was completed by confirming that excellent effects can be obtained by using styrene sulfonate instead of styrene.

Specifically, the dispersant for emulsion polymerization of the present invention is characterized by comprising a maleic acid or anhydride-styrene sulfonate copolymer.

[In-body explanation A] As mentioned above, the dispersant for emulsion polymerization of the present invention is a copolymer consisting of monomaleic acid or its anhydride and styrene sulfonate, and this is particularly suitable for emulsification of vinyl monomers. It is useful for use in polymerization reactions.

First, in the above copolymer, the first copolymerization component is maleic acid or its anhydride, but in addition to this, maleic acid monoester, maleic diester, maleic acid imide, or N-substituted maleic imide It is also possible to use maleic acid derivatives such as. On the other hand, the styrene sulfonate as the second copolymerization component is not particularly limited, but alkali metal salts such as sodium salts and potassium salts are preferred.

This copolymer can be produced, for example, as follows. That is, first, maleic acid or its anhydride and styrene are mixed with a catalyst such as benzoyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, lauroyl peroxide, dicumyl peroxide, azobisisobutyronitrile, etc. to produce a maleic acid or anhydride-styrene copolymer. This copolymer is then sulfonated by a conventional method to convert the copolymer component styrene into styrene sulfonic acid. Thereafter, this product is subjected to, for example, lying sodation to obtain the desired copolymer of the present invention as a sodium salt of sulfonic acid. In this step, the initial charging ratio of maleic acid or its anhydride to styrene is not particularly limited;
For example, it is preferable to set the amount of methyl ref to about 1 to 5 moles per mole of maleic acid or its anhydride. Moreover, the number average molecular weight of the copolymer finally obtained is 500 to 200,000, and even 1,00.
It is preferably 0 to 100,000. Note that this copolymer may be produced by directly copolymerizing maleic anhydride and styrene sulfonate.

[Examples] Examples 1 to 3 (1) Production of dispersant for emulsion polymerization Styrene and maleic anhydride were charged in the amounts shown in Table 1, and in the presence of penyl peroxide as a catalyst. Maleic acid was copolymerized at ℃.
A styrene copolymer was obtained. Then, 100g of this polymer
200 g of 98% sulfuric acid was added thereto, and the mixture was reacted at 100°C for 2 hours to effect sulfonation.

After that, add 500g of water to dilute this,
The sodium salt was obtained by carrying out lying sodation at 60°C. The obtained product was dried to obtain a dispersant for emulsion polymerization of the present invention comprising a maleic anhydride-styrene sulfonate copolymer. Table 1 also shows the charging ratio (mole ratio) of styrene to maleic anhydride and the number average molecular weight of the finally obtained copolymer.

Table 1 (2) Emulsion polymerization reaction of vinyl monomers Using the dispersant for emulsion polymerization obtained above, first, the dispersion state at the start of the emulsion polymerization reaction of vinyl acetate was evaluated. That is,
Water as reaction medium, potassium persulfate as polymerization initiator,
Sodium laurylbenzenesulfonate was used as a surfactant, and each was used in the indicated amounts (all parts by weight). First, after dissolving potassium persulfate, a surfactant, and a dispersant in water, vinyl acetate was added, and using a lab body spar (manufactured by Tokushu Kika Kogyo ■), the solution was dissolved at room temperature.
Stirred for 2 minutes at 1000 rpa+. Thereafter, stirring was stopped, and the dispersion state in the solution at the start of 1st polymerization was visually observed, and the results are shown in the table.

Next, an emulsion polymerization reaction of vinyl acetate was carried out using each component in the indicated amounts.

That is, an aqueous solution in which sodium laurylbenzenesulfonate and a dispersant were dissolved was prepared in a four-bottomed round-bottomed flask, and heated to 50° C. in a hot water bath while stirring. Next, vinyl acetate was added dropwise from the dropping funnel over a period of 14 hours. Meanwhile, potassium persulfate was dissolved in lO- water, and this aqueous solution was added in portions into the flask. At this time, the addition of the potassium persulfate aqueous solution was completed at the same time as the dropwise addition of vinyl acetate was completed. After that, 2
A time polymerization reaction was carried out to obtain a polymer emulsion of vinyl acetate. The emulsification state of this polymer emulsion was visually observed, and the results are shown in the table.

Comparative Examples 1 and 2 Polymerization was carried out in exactly the same manner as in Examples 1 to 3 above, except that NaOH neutralized products A and B of the maleic anhydride-isobutylene copolymer shown below were used as the dispersant for emulsion polymerization. The dispersion state at the beginning and the emulsification state of the obtained polymer emulsion were visually observed, and the results are also shown in the table.

A: Number average molecular weight [53,000, degree of neutralization 1, maleic anhydride: isobutyl = 1:1 (molar ratio) B: number average molecular weight 84,000, degree of neutralization 1, maleic anhydride: isobutyl = [Effects of the Invention] As is clear from the above explanation, when the dispersant for emulsion polymerization of the present invention is used in the emulsion polymerization reaction of vinyl yarn yarn, first, the dispersibility at the start of the polymerization reaction improves. In addition, the obtained polymer emulsion has a uniform emulsification state, so it is particularly useful in the field of producing vinyl polymers useful as raw materials for paper, wood processing agents, adhesives, paints, etc. Its usefulness is extremely high.

Claims (1)

[Claims] A dispersant for emulsion polymerization characterized by comprising a maleic acid or its anhydride-styrene sulfonate copolymer.