JPS6059243B2 - Method for producing aqueous polymer emulsion - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a polymer emulsion, and more particularly, to a method for producing an aqueous polymer emulsion using a high molecular weight vinyl copolymer as an emulsifier.

Aqueous synthetic resin emulsions are now widely used in paints, adhesives, paper and fiber treatment agents, etc.; This is because it is preferable compared to a solvent type from the viewpoint of environmental protection, work environment, resource saving, etc., and also because it has a relatively low viscosity even at high concentrations and has excellent workability.

However, one conventional synthetic resin aqueous emulsion is produced in the presence of a low molecular weight emulsifier such as an alkyl sulfonate, an alkyl sulfate, an alkyl carboxylate, etc., and it is difficult to form a film using such an emulsion. When this happens, the above-mentioned emulsifier remains in the film, resulting in a problem that the film has poor water resistance, heat resistance, weather resistance, etc. In addition, especially when producing an emulsion of acrylic resin, there are many aggregates, There was also the problem of poor mechanical stability.In order to solve these problems, several methods for producing aqueous polymer emulsions using high molecular weight emulsifiers have already been proposed, but the present invention does not address this technical field. By using a specific vinyl copolymer as a polymeric emulsifier, no aggregates are generated during emulsion polymerization, and the film formed by the emulsion has excellent physical properties such as water resistance, heat resistance, and weather resistance. It is an object of the present invention to provide a method for producing an aqueous polymer emulsion.

That is, the gist of the present invention is an ester of acrylic acid or methacrylic acid having a cyclic unsaturated compound represented by the general formula
．． 5 to 50% by weight and 5 to 5 α,β monounsaturated carboxylic acids
The present invention relates to a method for producing an aqueous polymer emulsion, which comprises carrying out aqueous emulsion polymerization of a radically polymerizable monomer using a vinyl copolymer having % by weight as a constituent unit as a polymer emulsifier.

Specific examples of esters of acrylic acid or methacrylic acid having a cyclic unsaturated compound used in the present invention include 3
(4) - Acryloxy 1 cyclopentene, (this is 3
-Means both acryloxy 1-cyclopentene and 4-acryloxy 1-cyclopentene.

same as below. ) 3(4)-methacryloxy 1-cyclopentene, 3(4)-acryloxy 2-methyl-1-cyclopentene, 4-acryloxy 3-methyl-1-cyclopentene, 3(4)-methacryloxy 2-methyl-1-cyclopentene, 4-methacryloxy Roxy 3-methyl-1-cyclopentene, 4(5)-acryloxy 1
-cyclohexene, 4(5)-methacryloxy 1-cyclohexene, 4(5)-acryloxy 2-methyl-1-cyclohexene, 4(5)-acryloxy 3-methyl-1-cyclohexene, 4(5)-methacryloxy 2-methyl-1- Cyclohexene, 4(5)-methacryloxy-3-methyl-1-cyclohexene, 5(6)
-acryloxybicyclo[2.2.1]-2-heptene, 5(6)-methacryloxybicyclo[2.2.1]-
2-heptene, 5(6) acryloxybicyclo [2.2
．． 1) -3-methyl-2-heptene, 5(6) acryloxybicyclo[2.2.1]-4-methyl-2-heptene, 5(6) methacryloxybicyclo[2.2.1)-
Examples include 3-methyl-2-heptene, 5(6)methacryloxybicyclo[2.2.1]-4-methyl-2-heptene, and the like. The vinyl copolymer used as a polymer emulsifier in the present invention contains the ester in an amount of 0.5 to 5% (
Hereinafter, % shall indicate weight %.

). If it is less than 0.5%, the resulting aqueous polymer emulsion will have poor air curability, and therefore,
Only a film with poor water resistance can be formed; on the other hand, if it exceeds 50%, the film formed by the emulsion is likely to be colored;
This results in poor weather resistance.

Furthermore, the vinyl copolymer contains α,β monounsaturated carboxylic acid as a structural unit in a range of 5 to 50% so as to have hydrophilicity, and generally has an acid value of 30 to 350.

If it is less than 5%, when emulsion polymerizing radically polymerizable monomers using such a vinyl copolymer as an emulsifier, the emulsifying ability is small and aggregates may form, making it difficult to obtain a good polymer emulsion. Moreover, when it exceeds 50%, it is not preferable because the emulsifying ability is low and the film formed by the resulting emulsion is poor in water resistance.

As such α,β monounsaturated carboxylic acids, acrylic acid, methacrylic acid, itaconic acid, crotonic acid, cinnamic acid, maleic acid, fumaric acid, etc. are preferably used.

The vinyl copolymer has a weight average molecular weight of 500 to 15
Preferably, it is in the range of 0000.

If the molecular weight is too small, the emulsifying ability will be low and it will be difficult to obtain a good emulsion, and if the molecular weight is too large, the viscosity will be too high when dissolved in water, so only a small amount can be used, and a good emulsion will not be obtained. This is because emulsions are difficult to obtain. Furthermore, in the present invention, the vinyl copolymer contains, in addition to the above-mentioned ester and α,β-monounsaturated carboxylic acid, other appropriate vinyl monomers as structural units from 0 to 94.5%.
It may be contained within a range of %.

Specific examples of such vinyl monomers include (meth)acrylics such as butyl (meth)acrylate, (this means both butyl acrylate and butyl methacrylate, the same applies hereinafter), and 2-ethylhexyl (meth)acrylate. Acid alkyl esters, (meth)acrylic acid hydroxyalkyl esters such as hydroxyethyl (meth)acrylate and hydroxypropyl (meth)acrylate, alkenylbenzenes such as styrene, α-methylstyrene, and vinyltoluene, as well as vinyl acetate and acrylonitrile. etc. can be mentioned. As mentioned above, a vinyl copolymer consisting of an ester of acrylic acid or methacrylic acid having a cyclic unsaturated compound, an α,β monounsaturated carboxylic acid, and other constituent units as necessary has been conventionally known to the general public. It can be obtained by copolymerizing each monomer according to the method described in the following.

The vinyl copolymer thus obtained is neutralized with a base to form an aqueous solution, which is used as an emulsifier for emulsion polymerization.

The above-mentioned base is not particularly limited, and various bases can be used, such as alkali metal hydroxides such as sodium hydroxide, alkali metal oxides, carbonates, bicarbonates, ammonia, and amines. Can be used. Specific examples of amines include triethylamine, diethanolamine, and tetramine. The aqueous solution of the vinyl copolymer neutralized in this way may contain a water-soluble organic solvent, and examples of these water-soluble organic solvents include ethylene glycol, propylene glycol, ethyl cellosolve, butyl cellosolve,
Examples include glycols such as butyl carbitol and butyl cellosolve acetate, and their alkyl ethers and alkyl ether esters. Next, according to the present invention, when emulsion polymerizing radically polymerizable monomers using the above-mentioned vinyl copolymer as an emulsifier, the amount of the vinyl copolymer used is usually monomer 1 (1). parts (hereinafter, all parts refer to parts by weight).

) to about 5 to 1 (1) parts. about. If it is less than 5 parts, emulsion stability during emulsion polymerization will be insufficient, and about 1 part
If the amount exceeds (1) part, the resulting film will have insufficient water resistance and chemical resistance. In addition, in order to further improve the dryness, water resistance, oil resistance, etc. of the film from the obtained emulsion, drying agents commonly used in paints, such as cobalt naphthenate, manganese naphthenate, lead naphthenate, An appropriate amount of zirconium naphthenate or the like may be added during emulsion polymerization, or may be added after polymerization.

In the present invention, the radically polymerizable monomer that can be emulsion polymerized using the vinyl copolymer as an emulsifier is not particularly limited,
Contains all monomers conventionally subjected to emulsion polymerization.

Specific examples include methyl (meth)acrylate, ethyl (meth)acrylate, butyl (meth)acrylate, 2-
In addition to (meth)acnolylic acid alkyl esters such as ethylhexyl (meth)acrylate and glycidyl (meth)acrylate, alkenylbenzenes such as styrene, α-methylstyrene, and vinyltoluene, as well as vinyl acetate,
Examples include vinylpyridine, butadiene, isoprene, chloroprene, acrylonitrile, methacrylonitrile, and the like. These monomers may be used alone or as a mixture of two or more, but if necessary, a small amount of acrylic acid, methacrylic acid, itaconic acid, maleic anhydride, acrylamide, methacrylamide, dimethylaminoethyl methacrylate may be added to these monomers. , N-methylolacrylamide, N-
Hydrophilic monomers such as butoxymethylacrylamide, 2-hydroxypyrobyl acrylate, 2-hydroxyethyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, and styrenesulfonic acid may be used in combination; , small amounts of glycol diacrylates and dimethacrylates such as ethylene glycol dimethacrylate, tetraethylene glycol diacrylate, butylene glycol dimethacrylate, neopentyl glycol dimethacrylate, and even polyfunctional crosslinking agents such as diallyl phthalate are used in combination. It's okay. In order to carry out emulsion polymerization in the present invention, conventionally known methods can be employed.

For example, in the presence of the above-mentioned vinyl copolymer, the above-mentioned monomers are mixed with a radical polymerization initiator in water or in an aqueous solution containing the above-mentioned water-soluble organic solvent, and if necessary, the above-mentioned hydrophilic monomers are added. Emulsion polymerization is carried out at a temperature of 0 to 100°C using a polyfunctional crosslinking agent, a drying agent, etc. The radical polymerization initiator may be water-soluble or oil-soluble, and includes, for example, peroxides such as benzoyl peroxide, cumene hydroperoxide, and hydrogen peroxide, azo compounds such as azobisisobutyronitrile, ammonium persulfate, and potassium persulfate. Redox catalysts such as persulfates, perchloric acid compounds, and combinations of persulfate compounds and reducing sulfoxy compounds can be used. Polymerization can also be initiated by irradiation with gamma rays or electron beams. The method of the present invention is configured as described above for H or CH3.

) A vinyl copolymer having as constituent units 0.5 to 50% by weight of acrylic acid or methacrylic ester having a cyclic unsaturated compound represented by Since it is used as a molecular emulsifier, the polymerization stability of the radically polymerizable monomer is good, that is, no aggregates are generated during emulsion polymerization, and the resulting aqueous polymer emulsion does not undergo phase separation even after being left for a long period of time. In other words, it has excellent storage stability, mechanical stability, and miscibility with pigments. Furthermore, since the emulsifier itself has high air curability due to the double bonds of the ester, the film formed by the emulsion has excellent water resistance, weather resistance, heat resistance, etc.

In addition, the resulting emulsion generally has excellent compatibility with water-soluble resins, and can be easily used in combination with epoxy resins, phenol resins, urea resins, melamine resins, etc., depending on the purpose of use, and can be used as a baking paint. is also possible.

Below, reference examples showing production examples of vinyl copolymers used as polymeric emulsifiers in the present invention and examples of the present invention are shown.

Reference Example 1 Butyl cellosolve 10 was placed in a 1' separable flask equipped with a stirrer, thermometer, dropping funnel, cooling tube and nitrogen introduction tube.
After charging 0fI, purging the inside of the flask with nitrogen and raising the temperature to 100°C, 72 g of 3-acryloxy-1-cyclopentene in which 8f of azobisisobutyronitrile and 2y of dodecyl mercaptan were dissolved, 31V of acrylic acid, and 97f of butyl methacrylate were added. It was added dropwise over 2 hours and stirred for an additional 3 hours to carry out the copolymerization reaction, resulting in an acid value of 103,
A colorless and transparent butyl cellosolve solution of a vinyl copolymer having a weight average molecular weight of 12,400 was obtained.

The composition ratio of the vinyl copolymer was approximately the same as the charge ratio of each monomer. Reference Example 2 In the same manner as in Reference Example 1, 3-acryloxy 1-cyclopentene 30f1 methacrylic acid 3
09,21'' 100y of ethylhexyl acrylate and 40f of styrene were added dropwise and stirred to carry out a copolymerization reaction to obtain a colorless and transparent butyl cellosolve solution of a vinyl copolymer with an acid value of 90 and a weight average molecular weight of 18,800. The composition ratio of the copolymer was approximately the same as the charge ratio of each monomer.Example 1 Into a 1e separable flask similar to Reference Example 1, 35y of the copolymer solution obtained in Reference Example 1 was added. 120 y of water and 5 y of 28% ammonia water were charged and stirred under a nitrogen atmosphere to neutralize and dissolve the copolymer.

Claims (1)

[Claims] 1. General formula▲There are mathematical formulas, chemical formulas, tables, etc.▼(In the formula, R
_1 is H or CH_3, R_2 is ▲There are mathematical formulas, chemical formulas, tables, etc.▼ or ▲There are mathematical formulas, chemical formulas, tables, etc.▼, and R_3 is H or CH_3. ), 0.5 to 50% by weight of an ester of acrylic acid or methacrylic acid having a cyclic unsaturated compound, and α,
A method for producing an aqueous polymer emulsion, comprising aqueous emulsion polymerization of a radically polymerizable monomer using a vinyl copolymer having 5 to 50% by weight of β-unsaturated carboxylic acid as a constituent unit as a polymer emulsifier. . 2. The manufacturing method according to claim 1, wherein the radically polymerizable monomer is an α,β-unsaturated carboxylic acid alkyl ester or alkenylbenzene. 3. The manufacturing method according to claim 1 or 2, wherein the ester of acrylic acid is acryloxy-cyclopentene. 4. The manufacturing method according to any one of claims 1 to 3, wherein the vinyl copolymer further contains an α,β-unsaturated carboxylic acid alkyl ester or alkenylbenzene as a constituent unit.