JPH05209008A - Production of emulsion polymer - Google Patents

Abstract

PURPOSE:To obtain an emulsion polymer having excellent solubility in a highly concentrated aqueous surfactant solution by copolymerizing an ethylenic monomer mixture containing an ethylenically unsaturated carboxylic acid (salt) in a specified proportion in the presence of a specified emulsifier and a specified polymerization initiator. CONSTITUTION:An ethylenic monomer mixture containing 10-50% ethylenically unsaturated carboxylic acid or a salt thereof is copolymerized in the presence of a sulfo-modified polyvinyl alcohol as an emulsifier and a water-soluble azo compound as a polymerization initiator.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for emulsion-polymerizing an ethylenic monomer to produce an emulsion polymer having excellent solubility in a highly concentrated aqueous surfactant solution.

[0002]

BACKGROUND OF THE INVENTION Shampoos, liquid detergents, etc. are aqueous solutions containing anionic surfactants at high concentrations. In order to fully function as a thickener or a dispersant in such an aqueous solution, it is necessary to exhibit good solubility in a highly concentrated aqueous surfactant solution.

It is known to use a sulfonic acid group-modified polyvinyl alcohol in the emulsion polymerization of an ethylenically unsaturated monomer such as an acrylate ester (Japanese Patent Publication No. 51-
In this method, potassium persulfate or the like is used as a polymerization initiator, and the obtained emulsion polymer does not exhibit sufficient solubility in a high-concentration aqueous surfactant solution.

[0004]

SUMMARY OF THE INVENTION It is an object of the present invention to produce a copolymer exhibiting excellent solubility in a high-concentration aqueous surfactant solution.

[0005]

The method for producing an emulsion polymer of the present invention comprises the step of adding an ethylenically unsaturated carboxylic acid or a salt thereof.
An ethylenic monomer containing 10 to 50 mol%, using a sulfonic acid group-modified polyvinyl alcohol as an emulsifier, and
It is characterized in that a water-soluble azo compound is used as a polymerization initiator for copolymerization.

[0006]

[Embodiment] In the ethylenic monomer which is a raw material monomer of the present invention, its content is 10 to 50 mol%, preferably 15 to
It is necessary that 45 mol% be ethylenically unsaturated carboxylic acid or a salt thereof.

If this amount is less than 10 mol%, an emulsion copolymer having sufficient solubility in a high-concentration surfactant aqueous solution cannot be obtained. On the other hand, when it exceeds 50 mol%, the emulsion polymerization itself does not proceed smoothly, which is difficult.

Examples of the ethylenically unsaturated carboxylic acid or its salt include methacrylic acid, acrylic acid, crotonic acid, maleic anhydride, fumaric acid and salts thereof, with methacrylic acid being particularly preferred.

Examples of the ethylenic monomer to be copolymerized with the ethylenically unsaturated carboxylic acid (salt) include acrylic acid ester, methacrylic acid ester, vinyl acetate, vinyl chloride, acrylonitrile, acrylamide, styrene and the like. Acid esters and methacrylic acid esters are preferred.

As the sulfonic acid group-modified polyvinyl alcohol used as an emulsifier, vinyl sulfonic acid,
(Meth) allyl sulfonic acid, styrene sulfonic acid, (meth) acrylate propyl sulfonic acid or salts thereof copolymerized with vinyl acetate and then saponified; or polyvinyl alcohol treated with bromine, chlorine or the like and then acid sulfite. The thing obtained by heating in a soda aqueous solution is mentioned. Specifically, Goracen L-3266 manufactured by Nippon Synthetic Chemical Industry Co., Ltd. may be mentioned.

The amount of these emulsifiers used is usually preferably 1 to 20% by weight based on the total ethylenic monomer. Further, with the sulfonic acid group-modified polyvinyl alcohol of the present invention,
Other emulsifiers such as nonionic surfactants such as polyoxyethylene alkylphenol and anionic surfactants such as polyoxyethylene alkyl ether sulfate ester salt can also be used in combination.

The water-soluble azo compound used as a polymerization initiator in the present invention includes azoamidine compounds such as 2,2-azobis (2-amidinopropane) hydrochloride (V-50 manufactured by Wako Pure Chemical Industries, Ltd.), 2 , 2'-Azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] (VA-086 manufactured by Wako Pure Chemical Industries, Ltd.), 4,4'-azobis (4-cyanokyl) (Varic acid)
Azocyano compounds and the like (such as V-501 manufactured by Wako Pure Chemical Industries) are suitable. The amount of the water-soluble azo compound used is preferably 0.01 to 0.5 mol% with respect to all the monomers.

The emulsion polymerization method can be carried out by any of batch addition, divided addition and continuous addition of the ethylenic monomer. It is also possible to emulsify the ethylenic monomer with an emulsifier and then add it as an emulsion. The method of adding the polymerization initiator may be batch addition, divided addition, or continuous addition. A particularly preferred method is
It is a continuous addition method of an ethylenic monomer and a divided addition method of a polymerization initiator.

The polymerization temperature is preferably 50 to 95 ° C., and the polymerization time is preferably 1 to 8 hours. The pH during the polymerization is 1 to 6, preferably 2 to 5
Is. Usually, the molecular weight of the produced polymer is 10,000 to tens of millions, and the polymer concentration in the emulsion is 10 to 45% by weight.

[0015]

The emulsion obtained by the present invention is
It excels in mechanical stability and aging stability, and shows excellent solubility in a high concentration aqueous solution of anionic surfactant, especially in a wide pH range of pH 4 to 11 from acidic to alkaline.

Therefore, for example, it can be dissolved in liquid cosmetics or household cleaners containing anionic surfactants at high concentrations, such as shampoos, kitchen and liquid detergents for clothes,
It is suitable as these thickeners or as a dispersant for organic and inorganic fine particles in these liquid compositions. These effects are first achieved by the combined use of the modified polyvinyl alcohol and the azo compound.

Further, for general chemical industry, it is also suitably used as a dispersant for pigments, clays, zeolites, iron oxides, etc., and as an emulsifier for rubber latex, asphalt, etc.

[0018]

【Example】

Example 1 In a separable flask having a volume of 1000 ml equipped with a reflux condenser, a dropping funnel, a stirrer, a nitrogen introducing tube, and a thermometer, sulfonic acid group-modified polyvinyl alcohol (PVA) (manufactured by Nippon Synthetic Chemical Industry Co., Ltd., Gocelan L- 3266) 6 g and 341.5 g of water were added and stirred to dissolve the sulfonic acid group-modified PVA. Ten
After bubbling 0 ml / min of nitrogen gas for 20 minutes to replace the inside of the reaction vessel with nitrogen and raise the internal temperature to 40 ° C., 2,2′-azobis (2-amidinopropane) hydrochloride (Wako Pure Chemical Industries, Ltd. V-50) 4.8% aqueous solution 8.9 g (1.58 × 10 ^-3 mol), methacrylic acid 2.2 g (0.026 mol) and ethyl acrylate 5.3 g (0.
053 mol) was added. Under nitrogen stream, stirring speed 250r
After the initial emulsification by stirring for 20 minutes at pm, the internal temperature is 70 ° C.
The temperature was raised to 42.4 g (0.493 mol) of methacrylic acid and 100.1 g (1.00 mol) of ethyl acrylate were continuously added dropwise over 2 hours. One hour after the end of dropping, 2,2'-azobis
(2-amidinopropane) hydrochloride 4.8% aqueous solution 1.8 g (3.2 x 1
0 ^-4 mol) was added and the mixture was aged for 1 hour. After cooling the reaction solution, it was filtered through an 80-mesh filter mesh to obtain a copolymer emulsion.

The solid content concentration of this emulsion is 30.6 wt%
Met. In addition, 3.3 g of this emulsion was added to 100 g of an aqueous solution containing sodium hydroxide in an amount equivalent to the carboxylic acid in the emulsion and stirred to obtain a transparent solution.

Examples 2 and 3 The total amount of the initiator 2,2'-azobis (2-amidinopropane) hydrochloride used in the polymerization was 4.8% aqueous solution in Example 2.
5.4 g (9.56 × 10 ⁻⁴ mol), in Example 3 21.5 g of 4.8% aqueous solution
(3.81 × 10 ⁻³ mol) and emulsion polymerization was carried out in the same manner as in Example 1 except for the above. The proportion of the divided addition of the initiator was 83.3% at the initial emulsification and 16.7% after the dropping in both Examples 2 and 3.

Examples 4 to 6 The monomer composition was a ternary system of methacrylic acid, ethyl acrylate and n-butyl acrylate. In Example 4, 34.3 g (0.398 mol) of methacrylic acid and 79.8 g (0.797 g) of ethyl acrylate were used.
Mol) and 35.9 g (0.280 mol) of n-butyl acrylate, and in Example 5, 45.1 g (0.524 mol) of methacrylic acid, 91.1 g (0.910 mol) of ethyl acrylate, n-butyl acrylate.
Using 13.8 g (0.108 mol), and in Example 6, 52.2 g (0.606 mol) of methacrylic acid, 66.8 g (0.667 mol) of ethyl acrylate, and 31.1 g (0.243 mol) of n-butyl acrylate were used for emulsion polymerization. I did.

After mixing the three types of monomers, 5 wt% of the total amount was added at the time of initial emulsification, and 95 wt% was heated and continuously added dropwise. The polymerization method was the same as in Example 1 except that 15 g of sulfonic acid group-modified PVA was used.

Example 7 Emulsion polymerization was carried out in the same manner as in Example 5 except that the polymerization temperature was 85 ° C.

Examples 8 and 9 2,2'-azobis [2-methyl-N- (2-hydroxyethyl) -propionamide] (VA-produced by Wako Pure Chemical Industries, Ltd. as a polymerization initiator in Example 8) 086) 11.2 g (1.86 × 10 ⁻³ mol) of 4.8% aqueous solution, 4,4′-in Example 9.
Azobis (4-cyanovaleric acid) (Wako Pure Chemical Industries, Ltd., V
Polymerization was carried out in the same manner as in Example 7, using 0.617 g (1.82 × 10 ⁻³ mol) of a −501) 84% product.

The proportion of the initiator dividedly added was 83.3% at the initial emulsification and 16.7% after the dropping was completed.
-Azobis (4-cyanovaleric acid) was charged as a solid into the reaction vessel.

Example 10 2,2'-azobis (2-amidinopropane) hydrochloride 4.
1.7 g (0.3 × 10 ^-3 mol) at the time of initial emulsification of 8% aqueous solution, 7.0 g (1.24 × 10 ^-3 mol) after heating at 85 ° C, 1.7 g (0.3 × 10 ^-3 mol) after dropping.
× 10 ^-3 mol) was added, except that the reaction temperature was 85 ° C. polymerization was carried out analogously to Example 5.

Example 11 Emulsion polymerization was carried out in the same manner as in Example 5 except that the polymerization initiator was added by the continuous dropping method to bring the polymerization temperature to 85 ° C. That is, 8.7 g (1.54 × 10 ⁻³ mol) of 4.8% aqueous solution of 2,2′-azobis (2-amidinopropane) hydrochloride was continuously added simultaneously with the monomer over 2 hours to conduct polymerization, and the addition was completed for 1 hour. Later, 1.7 g of a 4.8% aqueous solution was added all at once.

Comparative Example 1 Emulsion polymerization was carried out in the same manner as in Example 1 except that potassium persulfate was used as the polymerization initiator.

Comparative Example 2 6.5 g (0.076 mol) of methacrylic acid and 143.5 of ethyl acrylate
Using g (1.43 mol), emulsion polymerization was carried out in the same manner as in Example 1.

Comparative Example 3 Methacrylic acid 84.5 g (0.98 mol), ethyl acrylate 65.5 g
(0.65 mol) was used (methacrylic acid / ethyl acrylate = 6
Polymerization was carried out in the same manner as in Example 1 (0/40 molar ratio), but thickening of the reaction solution and formation of aggregates were observed during the reaction, and a stable emulsion polymer could not be obtained. ..

Evaluation of Solubility Each of the emulsion polymers obtained in Examples 1 to 11 and Comparative Examples 1 and 2 was evaluated for solubility in a surfactant solution by the following method, and the results are shown in Table 1. Show.

(1) Method for evaluating solubility in surfactant solution Sodium polyoxyethylene lauryl ether sulfate
3.3 g of the emulsion was dissolved in 100 g of an aqueous solution containing 20 wt% (average number of moles of ethylene oxide added = 3.0) and 10 wt% of diethanolamine, and the dissolved state was visually determined. ○: dissolved △: gel-like insoluble matter present

[0033]

[Table 1] * 1) MAA: Methacrylic acid EA: Ethyl acrylate n-BuA: n-Butyl acrylate * 2) Potassium persulfate is used as a polymerization initiator.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Internal reference number FI technical display location C08F 222/04 MLR 7242-4J

Claims (1)

[Claims] 1. An ethylenic monomer containing 10 to 50 mol% of an ethylenically unsaturated carboxylic acid or a salt thereof, a sulfonic acid group-modified polyvinyl alcohol is used as an emulsifier, and a water-soluble azo compound is used as a polymerization initiator. A method for producing an emulsion polymer, which comprises copolymerizing.