JPS6234901A - Dispersing agent for emulsion polymerization - Google Patents

Abstract

PURPOSE:To provide the titled dispersing agent composed of a copolymer of isobutylene, maleic acid ( or its anhydride) and styrenesulfonic acid salt and capable of improving the dispersibility of monomer and giving stable emulsion when applied to the emulsion when applied to the emulsion polymerization of a vinyl monomer. CONSTITUTION:A copolymer of isobutylene, maleic acid (or its anhydride) and styrene is produced e.g. by reacting 1mol of isobutylene, 0.5-5mol of maleic acid or its anhydride and 0.01-5mol of styrene optionally in a solvent such as nitromethane in the presence of a catalyst such as benzyl peroxide, preferably at 45-150 deg.C for 1-10hr. The copolymer is sulfonated and converted to a sulfonic acid salt to obtain the objective copolymer of isobutylene, maleic acid (or its anhydride) and styrenesulfonic acid salt useful as a dispersing agent. USE:Useful in the field for producing a vinyl polymer useful as a raw material of paper and wood-processing agent, adhesive, etc.

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 an emulsion polymerization method for vinyl monomers to improve the dispersibility of 1,000 yen. The present invention relates to a dispersant for emulsion polymerization that can produce a polymer emulsion in a stable and 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 monomers by adding them.

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 above-mentioned vinyl monomer, the polymerization reaction cannot proceed smoothly because the dispersibility of the monomer in water is not very good. Furthermore, there was a problem that the stability of the obtained polymer 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 inventor has developed a conventional maleic anhydride-imbutylene copolymer as a copolymer constituting a dispersant for emulsion polymerization. 3 in which styrene sulfonate was further introduced into the polymer as a third copolymerization component.
The present invention was completed after confirming that excellent effects can be obtained by employing the original copolymer.

That is, the dispersant for emulsion polymerization of the present invention is characterized by comprising inbutylene-maleic acid or its anhydride-styrene sulfonate.

[Specific Description] As mentioned above, the dispersant for emulsion polymerization of the present invention is a ternary copolymer containing isobutylene, maleic acid or its anhydride, and styrene sulfonate as copolymerization components,
This product is particularly useful for emulsion polymerization reactions of vinyl monomers.

One of the copolymerization components of this ternary copolymer is maleic acid or its anhydride, but it is not limited to this.In addition, maleic acid heptanoester, maleic acid diester, maleic acid imide Alternatively, maleic acid derivatives such as N-substituted maleic acid imide can also be used.

On the other hand, the styrene sulfonate as the other copolymerization component is not particularly limited, but alkali metal salts such as sodium salts and potassium salts are preferred.

In such a copolymer, the composition ratio of each copolymer component is not particularly limited, but for example, inbutylene
0.1 mole of maleic acid or its anhydride.
It is preferable to set the amount to be 5 to 5 mol and the styrene sulfonate to 0.01 to 5 mol, respectively. Also,
The number average molecular weight of this copolymer is 500 to 200,000.
, and more preferably from 1,000 to 100,000.

This copolymer can be produced, for example, as follows. That is, first, an inbutylene-maleic anhydride-styrene copolymer is obtained by reacting predetermined amounts of isobutylene, maleic anhydride, and styrene in the presence of a solvent and a catalyst if desired. At this time, the reaction temperature is preferably set at 45 to 150°C, and the reaction time is preferably set at 1 to 10 hours. The solvents used include acetontrile, tromethane, nitroethane,
Examples include methyl ethyl ketone, acetone, N,N-dimethylformamide, dimethyl sulfoxide, etc.
On the other hand, examples of the catalyst include benzoyl peroxide, cumene hydroperoxide, tertiary butyl hydroperoxide, lauroyl peroxide, dicumyl peroxide, and azobisisobutyronitrile.

The 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, liming sodation to obtain the desired copolymer of the present invention as a sodium salt of sulfonic acid.

In addition to the method described above, the copolymer of the present invention can also be produced by directly copolymerizing inbutylene, maleic anhydride, and styrene sulfonate.

[Examples] Examples 1 to 3 (1) Production of dispersant for emulsion polymerization In a rotary autoclave with an internal volume of 11, imbutylene,
Maleic anhydride and styrene were charged in the amounts shown in Table 1, and benzoyl peroxide O0θg was added as a catalyst, and acetonitrile 460g was added as a solvent.
After charging -, a copolymerization reaction was carried out for 2 hours at 110°C and 1400 rpm.

After the reaction was completed, the product was poured into water to obtain an isobutylene-maleic anhydride-styrene copolymer.

Next, after crushing this material, 1 (lag
200g of 98% sulfuric acid was added, and the mixture was heated at 100℃ for 2 hours.
Sulfonation was carried out by reaction for a period of time. Thereafter, this product was diluted with 500 g of water and subjected to liming sodation at 80°C to obtain a sodium salt. The obtained product was dried to obtain a dispersant for emulsion polymerization of the present invention comprising an isobutylene-maleic anhydride-styrene sulfonate copolymer. Table 1 shows the charging ratio (mole ratio) of isobutylene, maleic anhydride, and styrene.
The number average molecular weight of the finally obtained copolymer is also shown.

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 mixture was heated for 1 hour at room temperature.
Stirred for 2 minutes at 000 rpm+s. Thereafter, the stirring was stopped, and the state of dispersion in the solution at the start of 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 round-bottomed four-eye flask, and heated in a hot bath to 50° C. while stirring. Next, vinyl acetate was added dropwise from the dropping funnel over a period of 1 hour. Meanwhile, potassium persulfate was dissolved in 10 d of 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,
The polymerization reaction was carried out for 1 hour to obtain a polymerized 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 Maleic anhydride shown below was used as a dispersant for emulsion polymerization.
The dispersion state at the start of polymerization and the emulsification state of the obtained polymer emulsion were visually observed in exactly the same manner as in Examples 1 to 3 above, except that NaOH neutralized products A and B of isobutylene copolymer were used. The results are also listed in the table.

A: Number average molecular weight 53,000, degree of neutralization 1, maleic anhydride: isobutylene = 1:0.8 (mole ratio) B: number average molecular weight 84,000, degree of neutralization 1, maleic anhydride: isobutylene = 1 : 0.8 (mole ratio) [Effect 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 thread yarn, first, the polymerization reaction starts. In addition, the resulting polymer emulsion has good dispersibility and a uniform emulsified state, making it particularly useful for vinyl polymers that are useful as raw materials for paper, wood processing agents, adhesives, paints, etc. In the manufacturing field.

Its usefulness is extremely high.

Claims (1)

[Claims] A dispersant for emulsion polymerization, characterized in that it consists of an isobutylene-maleic acid or anhydride-styrene sulfonate copolymer.