JPH0832730B2 - Method for producing ultrafine polymer latex - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for producing an ultrafine-particle polymer latex by emulsion-polymerizing an unsaturated monomer.

[Prior art]

Conventionally, a method for producing a polymer latex by emulsion polymerization of an unsaturated monomer in the presence of an emulsifier is known, but the particle size of the polymer latex obtained by such a method is large, and the formed film is However, it has a drawback that it is inferior in performance such as transparency, smoothness, water resistance, or solvent resistance to a film of an organic solvent type polymer.

In order to improve these drawbacks, a redox catalyst consisting of a persulfate and a reducing sulfoxy compound was used with a polymerization initiator containing a trace amount of a transition metal ion as an accelerator to make the particles of the polymer latex into ultrafine particles. Further, a method has been proposed in which an appropriate three-dimensional structure is generated in a polymer latex to improve the film performance (Japanese Patent Laid-Open Nos. 60-170604 and 60-170605).

However, in these methods, the particle size of the polymer latex produced is greatly different due to the influence of a small amount of the transition metal ion used as a polymerization accelerator, and further, the formed film is inferior in transparency and water resistance. In addition, it has a drawback that it is dissolved or swelled when it comes into contact with an organic solvent, which is not an industrially advantageous method.

〔Purpose〕

The object of the present invention is to make a polymer latex into an ultrafine particle and have a film forming ability excellent in transparency and smoothness. Further, a polymer latex is already cross-linked and has a film forming ability excellent in water resistance and solvent resistance. An object of the present invention is to provide a method for industrially producing the polymer latex having the polymer latex.

〔Constitution〕

According to the present invention, there is provided a method for producing an ultrafine-particle polymer latex, which comprises emulsion-polymerizing an ethylenically unsaturated monomer in the presence of an emulsifier, using an azo compound as a polymerization initiator at 70 ° C or lower. To be done.

In the present invention, an azo compound is used as a polymerization accelerator, and it is an essential requirement that the ethylenically unsaturated monomer is emulsion-polymerized at 70 ° C. or lower, so that it is excellent in water resistance, transparency and solvent resistance. It is possible to industrially obtain an ultrafine-particle polymer latex having a film-forming ability.

The reason why the above-mentioned ultrafine-particle polymer latex is obtained by the emulsion polymerization method of the present invention and the reason why this latex has excellent film properties is not always clear at this point, but the azo used as a polymerization initiator in the present invention is not always clear. Since the decomposition temperature of the compound is low and many radicals are generated at a relatively low temperature, the polymerization is promoted, the coalescence of the produced polymer latex is suppressed, and the particles of the produced polymer latex are ultrafine particles, It is considered that this is due to the provision of a film having excellent transparency and smoothness. Further, in the present invention, as an emulsifier in the emulsion polymerization,
When a polyoxyalkylene ethylenically unsaturated carboxylic acid polyester and / or betaine ester to be described later is used or as a raw material unsaturated monomer (as an ethylenically unsaturated monomer), an unsaturated monomer having a reactive functional group is used. When an unsaturated monomer containing 1 to 10% by weight of a monomer is used,
Further, it is possible to obtain an ultrafine-particle polymer latex which gives a film having excellent properties such as water resistance and solvent resistance.

Although it is not clear why the present invention can obtain an ultrafine particle polymer latex having more excellent performance by selecting a specific reaction mode as described above, polyoxyalkylene ethylenically unsaturated carboxylic acid polyester emulsifier or betaine Since the ester-type emulsifier has a specific structure, these emulsifiers form a special bond such as an ionic bond, a hydrogen bond or a self-condensation in the emulsion polymerization step and the film forming step, or participate in the crosslinking reaction. Has a strong three-dimensional structure,
It is believed that an ultrafine-particle polymer latex that gives a film having excellent transparency, smoothness, water resistance and solvent resistance can be obtained.

Further, as the raw material unsaturated monomer, active hydrogen, even when using an unsaturated monomer having a reactive functional group such as an epoxy group, these reactive functional groups during the emulsion polymerization reaction, hydrogen bonds and By forming a special bond such as self-condensation and intervening in the cross-linking reaction, the formed film of polymer latex has a strong three-dimensional structure, transparency,
It is presumed that an ultrafine particle polymer latex that gives a film having excellent smoothness, water resistance and solvent resistance can be obtained.

 Hereinafter, the present invention will be described in more detail.

In the present invention, an azo compound is used as a polymerization initiator, and particularly 2,2′-azobis (N, N′-alkylenealkylamidine) represented by the following general formula (I) or a salt thereof is preferably used. .

(In the formula, R ₁ represents an alkyl group having 1 to 6 carbon atoms or a cycloalkyl group, and R ₂ represents an alkylene group having 1 to 6 carbon atoms.) 2,2′-azobis represented by the general formula (I) (N,
Specific examples of N'-alkylenealkylamidine) include the compounds shown below.

2,2'-azobis (N, N'-methyleneisobutylamidine), 2,2'-azobis (N, N'-methylene-2-cyclopropylpropioamidine), 2,2'-azobis (N, N ′ -Dimethyleneisobutylamidine), 2,2′-azobis (N, N′-dimethylene-2-cyclopropylpropionamidine), 2,2′-azobis (N, N′-dimethylene-2-methyl-)
Butylamidine), 2,2'-azobis (N, N'-dimethylene-2,4-dimethylpentylamidine), 2,2'-azobis (N, N'-dimethylene-2-methyl-)
3-cyclopropylpropioamidine), 2,2'-azobis (N, N'-dimethylene-2-methyl-)
Hexylamidine), 2,2'-azobis (N, N'-trimethyleneisobutylamidine), 2,2'-azobis (N, N'-tetramethyleneisobutylamidine), 2,2'-azobis (N, N ′ -Trimethylene-2,4-dimethylpentylamidine), 2,2′-azobis (N, N′-trimethylene-2-cyclopropylpropioamidine), 2,2′-azobis (N, N′-trimethylene- 2-methyl-hexylamidine), 2,2'-azobis (N, N'-tetramethylene-2-butylamidine), 2,2'-azobis (N, N'-tetramethylene-2-methyl-3-) Cyclopropylpropioamidine), 2,2'-azobis (N, N'-pentamethylene-2-methyl-hexylamidine), 2,2'-azobis (N, N'-trimethylene-2-cyclopropylpropio) Amidine) etc.

In addition, examples of these salts include those shown below.

(1) Inorganic acid salt Hydrochloride, sulfate, nitrate, phosphate, carbonate and the like.

(2) Organic acid salt Formate salt, acetate salt, propionic acid, butyrate salt, citric acid, tartrate salt, acrylate salt, methacrylate salt, benzoate salt,
Hydroxybenzoate, etc.

(3) Sulfonate Methanesulfonate, benzenesulfonate, toluenesulfonate, styrenesulfonate, acrylsulfonate, methallylsulfonate, etc.

Such an azo compound is generally extremely active at low temperatures and has excellent solubility in water. In particular, the salt type has an extremely high decomposition rate as compared with the conventional water-soluble polymerization initiator, and therefore the salt type is preferably used in the present invention.

The azo compound used in the present invention can be produced by a conventionally known method. For example, 2,2′-azobis (N, N′-alkylenealkylamidine) represented by the general formula (I) corresponds to 2,2'-azobisalkanenitrile is made into an iminoether and then easily obtained by reacting with a corresponding alkylenediamine.
The salt is produced by reacting the various acids mentioned above.

The azo compounds represented by the general formula (I) or salts thereof preferably used in the present invention have excellent storage stability, and thus can be directly used as they are.

The addition amount of the polymerization initiator used in the present invention is 0.01 to 10% by weight, preferably 0.05 to 5% by weight, based on the ethylenically unsaturated monomer used.

The above-mentioned azo compound which is the polymerization initiator of the present invention can be used alone or in combination of two or more kinds, and can also be used in combination with other polymerization initiators. Other polymerization initiators that can be used in combination include those usually used in this type of polymerization reaction, for example, 2,2'-azobis (2-amidinopropane) or its organic salt or its inorganic salt.

The emulsion polymerization temperature of the emulsion polymerization using the azo compound of the present invention as an initiator is 70 ° C. or lower, preferably 50 to 70 ° C. When the emulsion polymerization temperature exceeds 70 ° C, the decomposition rate is remarkably fast and a large number of radicals are generated, and ultrafine particle polymer latex can be generated at the initial stage of the polymerization. Since the polymer latices coalesce to form a large amount of polymer latices having a large particle size, the intended purpose of the present invention cannot be achieved.

As the emulsifier used when producing the ultrafine particle polymer latex of the present invention, any of conventionally known anionic surfactants, nonionic surfactants and cationic surfactants can be used. However, in order to obtain an ultrafine-particle polymer latex that gives a film having excellent transparency, smoothness, water resistance and solvent resistance,
It is particularly preferable to use a polyoxyalkylene ethylenically unsaturated carboxylic acid polyester type emulsifier and / or a betaine ester type emulsifier.

Examples of the polyoxyalkylene ethylenically unsaturated carboxylic acid polyester emulsifier preferably used in the present invention include those represented by the following general formula (II).

(In the formula, R ₃ and R ₄ ; hydrogen or a methyl group R ₅ ; alkylene group having 2 to 4 carbon atoms l, m; 1 to 50 real number A; _{O-C n H 2n-g} (R 8) g -O- R 6, R 7; alkyl group R ₈ hydrogen or C 1-2; _hydrogen, R _{5 O} n H or y; a real number of 0 to 5; an integer of 0 to 10; a real number of 2 to 50) Also, one type of —R ₅ O—, ethylene oxide, propylene oxide, butylene oxide, or two or more types,
It is preferably a unit introduced by addition-polymerizing ethylene oxide. When two or more kinds of alkylene oxides are added, the addition form may be random addition or block addition. The polyoxyalkylene ethylenically unsaturated carboxylic acid polyester represented by the general formula (II) can be produced by a conventionally known method.

Examples of betaine ester type surfactants preferably used in the present invention include the following general formula (III)
A betaine ester of a high-aliphatic alcohol represented by (VI), a betaine ester of a polyoxyalkylene alkyl ether, a betaine ester of a polyoxyalkylene phenyl ether, a betaine ester of a polyoxyalkylene dialkyl phenyl ether, and two or more benzene nuclei Examples thereof include betaine esters of polyoxyalkylene phenyl ethers and betaine esters of polyoxyalkylene polyhydric alcohol ethers.

(In the formula, The polyhydric shows the alcohol residue or alkylene oxide adducts thereof, _{also, R 9, R 10, R} 11, R 12, R 13, R 14,
R ₁₅ , R ₁₆ , R ₁₇ , a, b, c, m, p, q, X and Y
Represents the following respectively.

R ₉ : an alkyl group or an alkenyl group having 8 to 30 carbon atoms,
It may be linear or branched and preferably has 10 to 26 carbon atoms.

R _10; alkylene group having 2 to 4 carbon atoms, R _11; alkylene group having 1 to 5 carbon _{atoms, R 12, R 13, R} 14; or an alkyl group having 1 to 3 carbon atoms, -C
₂ H ₄ OH, which may be the same or different.

R ₁₅ and R ₁₆ ; an alkyl group having 6 to 20 carbon atoms or hydrogen, at least one of which is an alkyl group having 6 to 20 carbon atoms R ₁₇ ; an alkyl group having 1 to 20 carbon atoms or hydrogen a, b , C; shows the average number of moles added, a = 0 to 20 real numbers,
b = 0 if either R ₁₅ or R ₁₆ is an alkyl group
A real number of -20, a real number of 1-30 when both R ₁₅ and R ₁₆ are alkyl groups, a real number of c = 1-30 m; an integer of 8-20 p; an integer of 2-5 q; 0 However, p + q is an integer of 2-5.

X; inorganic or organic anion Y; And y: real numbers R ₁₈ and R _{19 of} 1 to 5: hydrogen or an alkylene group having 1 to 20 carbon atoms Y ′: an alkylene group having 3 to 8 carbon atoms, oxygen, sulfur, or a carbonyl group —R ₁₀ O— , Ethylene oxide, propylene oxide,
It is a unit introduced by addition-polymerizing one kind or two or more kinds of butylene oxide, preferably ethylene oxide. When two or more kinds of alkylene oxides are added, the addition form may be random addition or block addition.

The inorganic anion of X is a halide such as Cl ⁻ , Br ^−, and the organic anion is CH ₃ COO ⁻ , OSO ₃ CH ₃ ⁻ , O.
SO ₃ C ₂ H ₅ ^-, and the like as a typical example. ) Such betaine ester type emulsifiers can be obtained by various conventionally known synthetic methods.

Specific examples of emulsifiers comprising known anionic, nonionic and anionic surfactants include higher alcohols, higher alcohol alkylene oxide adducts, alkylphenol alkylene oxide adducts and styrenated phenol alkylene oxide adducts of the sulfate type, α -Olefin sulfonates such as olefins, quaternary ammonium salt types of long chain alkylamine oxide alkylene adducts and dilong chain alkylamine alkylene oxide adducts, N
Examples include sodium salt of-(1,2-dicarboxyethyl) -N-octadecyl sulfonic acid monoamide, dialkyl sulfosuccinate and the like.

Also, any of these emulsifiers can be used alone,
In particular, when producing a polymer latex of ultrafine particles having a film forming ability excellent in transparency, smoothness, water resistance and solvent resistance, as an emulsifier used for emulsion polymerization of an ethylenically unsaturated monomer, ( a) the above general formulas (III), (IV),
The betaine ester type emulsifiers represented by (V) and (VI) and (b) the polyoxyalkylene ethylenically unsaturated carboxylic acid polyester type emulsifier represented by the general formula (II) are (a) / (b) = 1 / It is preferably 2/8 to 8 in a weight ratio of 9 to 9/1.
Used in a / 2 weight ratio. If this ratio is less than 1/9, cracks are likely to occur in the film formed by the polymer latex produced, resulting in poor transparency and smoothness of the film. Also, 9 /
If it is larger than 1, the solvent resistance of the film may be poor.

As the ethylenically unsaturated monomer used in the present invention,
(Meth) acrylic acid esters represented by the following general formula (VII) (In the formula, R ₂₀ and R ₂₁ are hydrogen or a methyl group, R ₂₂ is an alkyl group having 1 to 18 carbon atoms), vinyl acetate, vinyl propionate, vinyl butyrate and other lower fatty acid vinyl esters, acrylonitrile,
Methacrylonitrile, styrene, α-methylstyrene,
Examples are vinyl chloride and vinylidene chloride.

In the present invention, as the unsaturated monomer to be copolymerized with the ethylenically unsaturated monomer, an unsaturated monomer having a reactive functional group is preferably used, but an unsaturated monomer having no reactive functional group is used. It is also possible to use an unsaturated monomer that can be converted to a compound having active hydrogen in the emulsion polymerization system even if it is a monomer.

Examples of the unsaturated monomer having such a reactive functional group include compounds represented by the following general formulas (VIII) to (XIV), and these monomers may be used alone or in combination of two or more. They can be used in combination, and if necessary, other copolymerizable unsaturated monomers can be used in combination.

(In the formula, R ₂₃ , R ₂₄ , R ₂₅ , R ₂₆ , R ₂₇ , R ₂₈ , R ₂₉ , B,
D, E, G, t ₁ , t ₂ and t ₃ are as follows.

R ₂₃ , R ₂₄ , R ₂₈ ; hydrogen atom or alkyl group having 1 to 3 carbon atoms R ₂₅ ; alkylene group having 2 to 4 carbon atoms R ₂₆ ; direct bond, alkylene group having 1 to 3 carbon atoms, phenylene group or substitution Phenylene group R ₂₇ ; oxygen atom or —NH—R ₂₉ ; alkylene group having 1 to 4 carbon atoms B; methylene group or carbonyl group D; methylene group or carboxyl group E; hydrogen atom, alkyl group having 1 to 3 carbon atoms, Carboxyl group, Or —CONHCONH G; hydrogen atom, alkyl group having 1 to 3 carbon atoms or CH ₂ COOH t ₁ ; real number of ₁ to 20 t ₂ ; integer of 0 or 1 t ₃ ; integer of 0 to 10) general formula (VIII) , (IV), (X), (XI), (XII)
Specific examples of the compounds of and (XIII) include the compounds shown below.

Example of general formula (VIII) Glycidyl acrylate Glycidyl methacrylate Glycidyl crotonate Glycidyl allyl ether Example of general formula (IX) Polyoxyethylene monoacrylate Polyoxyethylene monomethacrylate Polyoxyethylene monotonate Polyoxypropylene monoacrylate Polyoxypropylene monomethacrylate Polyoxypropylene monotonate Polyoxybutylene monoacrylate Polyoxybutylene monotonate Hydroxy Ethyl allyl ether Hydroxypropyl allyl ether Hydroxybutyl allyl ether Polyoxyethylene allyl ether Polyoxypropylene allyl ether Polyoxybutylene allyl ether Examples of general formula (X) Allylamine Acrylic amine Methacrylamine Aminostyrene α-methylaminostyrene General formula (XI ) Acrylamide methacrylamide dimethyl acrylamide dimethyl methacrylamide dimethyl aminopropyl acrylamide example of general formula (XII) acrylic acid methacrylic acid crotonic acid itaconic acid maleic acid and its anhydride fumaric acid and its anhydride maleic alanide fumaralanide N-carbamoyl malein Acid amide N-carbamoyl fumarate amide Example of general formula (XIII) Methylallylthiol Methyl Lukatostyrene Examples of general formula (XIV) N-methylol acrylic acid amide N-methylol methacrylic acid amide N-methylol crotonic acid amide N- (2-hydroxyethyl) acrylic acid amide N- (2-hydroxyethyl) methacrylic acid amide N- (2-hydroxypropyl) acrylic acid amide N- (2-hydroxypropyl) methacrylic acid amide The above ethylenically unsaturated monomer and the unsaturated monomer having a reactive functional group are used at a ratio of 99/1. ~ 9/1 wt%,
It is preferably 99/1 to 93/7% by weight. This usage rate is 99
If it is larger than / 1, the crosslink density generated in the film formed by the polymer latex formed will be small, so the film lacks solvent resistance, and if it is less than 9/1, the film forming property of polymer terax will be poor, and the film It is not preferable because cracks occur on the surface and the smoothness of the film is poor.

Further, in the present invention, when a betaine ester is used as an emulsifier, it is desirable to adjust and adjust the pH in the emulsion polymerization step to less than 6, preferably 3 to 6.
If the pH is 6 or more, a large amount of aggregates deviating from the intended physical properties are generated in the emulsion polymerization step, which is not preferable.

Then, in the presence of an emulsifier of the monomer having an unsaturated bond, the azo compound as a polymerization initiator, in producing an ultrafine-particle polymer latex by emulsion polymerization at 70 ℃ or less, conventionally known emulsion The polymerization method can be applied as it is.

For example, 0.01 to 10% by weight of the monomer having an unsaturated bond
The monomer having an unsaturated bond may be emulsified and dispersed in water at a concentration of 20 to 60% by weight in the presence of a polymerization initiator corresponding to the above to carry out emulsion polymerization. At this time, if necessary,
A nonionic surfactant, a cationic surfactant, an insoluble nonionic polymer substance, a cationic polymer substance, etc. can be used in combination. Further, a plasticizer and a pH adjuster which are usually used in the conventional method can be used in combination, if necessary.

As the nonionic surfactant, polyoxyethylene alkyl ether type, polyoxyethylene alkylphenyl ether type, polyoxypropylene-polyoxyethylene glycol (Pluronic) type, polyoxyethylene aliphatic ester type, polyoxyethylene alkylamine type, Examples thereof include polyoxyethylene-polyoxypropylene polyamine type (including Tetronic type).

As the cationic surfactant, long-chain alkyltrimethylammonium salt, long-chain alkylpyridinium chloride, polyoxyethylene long-chain alkylammonium salt,
Examples include long-chain alkylbenzyl trimethyl ammonium salts.

Examples of the nonionic polymer include polyvinyl alcohol, dextrin, starch derivatives such as hydroxyethyl starch and hydroxypropyl starch, hydroxyethyl cellulose, hydroxypropyl cellulose and the like.

Further, as the cationic polymer substance, cationic hydroxyethyl cellulose, cationic starch, cationic guar gum, cationic chitosan and cationic (meth) acrylic acid amide, cationic (meth) acrylic acid amide, dimethyldiallylammonium chloride. And the like.

These nonionic surfactants, cationic surfactants, nonionic polymeric substances and cationic substances can be appropriately used alone or in combination of two or more, the addition amount of which is 0.05 with respect to the emulsification target monomer. ~ 5% by weight, preferably
It is suitable to use 0.1 to 3% by weight.

As the plasticizer, phthalic acid ester, phosphoric acid ester and the like can be used. Further, as a pH adjuster, salts of sodium carbonate, sodium bicarbonate, sodium acetate, etc. are added to 0.01
~ 3% by weight can be used in combination, but as mentioned above, pH
Is preferably adjusted to less than 6.

〔effect〕

The present invention is composed of the above-mentioned composition, and uses an azo compound as a polymerization initiator, the emulsion polymerization temperature is 70 ° C. or lower, and the ethylenically unsaturated monomer is emulsion-polymerized in the presence of an emulsifier. It is possible to obtain an ultrafine-particle polymer latex that forms a film having excellent properties and smoothness.

In the present invention, the polyoxyalkylene ethylenically unsaturated carboxylic acid polyester and / or betaine ester type emulsifier described above is used as an emulsifier, and an unsaturated monomer having a reactive functional group as a raw material unsaturated monomer is further used. By using the body, it is possible to obtain an ultrafine-particle polymer latex that forms a film with various performances such as water resistance and solvent resistance further improved, and since its operation process is simple, industrial This is a very advantageous manufacturing method.

〔Example〕

Next, in order to explain the present invention in more detail, examples will be shown below.

Example 1 A glass reaction vessel equipped with a thermometer, a stirrer, a reflux condenser, a nitrogen inlet tube and a dropping funnel was charged with 3 parts by weight of the emulsifier shown in Table 1 and 150 parts by weight of water and dissolved therein. The gas was replaced. Separately, unsaturated monomer mixture consisting of 90 parts by weight of ethyl acrylate and 60 parts by weight of methyl methacrylate
150 parts by weight was prepared, and 15 parts by weight of this was added to the reaction vessel, and the mixture was emulsified at 40 ° C. for 30 minutes. Then, after raising the temperature to 60 ° C., the polymerization initiator shown in Table 1 was added to 9.0 × 10 ⁻³ mole /
It is dissolved in 50 parts by weight of water so as to be an aqueous phase l, added to the above reaction vessel, and immediately the rest of the unsaturated monomer is continuously dropped into the reaction vessel over 30 minutes and polymerization is carried out at 60 ° C. I went. After completion of the dropwise addition of the unsaturated monomer, the mixture was aged at 60 ° C. for 60 minutes.

The particle size of the polymer latex thus obtained was measured by Coulter submicron particle analyzer (Coulter model N4 type, manufactured by Coulter Electroix Co., USA).
It was measured at. In addition, the film properties were adjusted so that the polymer latex and solid content would be 20% by weight, and then 5 g
It was cast on an m × 8 cm glass plate, air-dried at room temperature to form a film, and measured. The film characteristics were evaluated according to the following criteria.

Transparency: integrating sphere type light transmittance measuring device (manufactured by Suga Test Instruments Co., Ltd.
The haze value of the film was measured by using an SM color computer SM-4-CH-H ₂ type).

Smoothness: The surface condition of the film was visually observed and evaluated according to the following criteria.

○ ・ ・ ・ Smooth and glossy film △ ・ ・ ・ Slightly wrinkled and cracked film × ・ ・ ・ Excessively wrinkled and cracked film Water resistance; Air-dried film of petri dish filled with water at 20 ° C It was dipped in the medium and the time until the 8-point newspaper type laid under the petri dish became unreadable was measured.

(Unit: time) Solvent resistance: The film after air-drying was peeled from the glass plate and immersed in a petri dish filled with benzene at 20 ° C for 48 hours, and the degree of swelling was calculated from the area ratio of the film to obtain solvent resistance. .

A: Area of film before immersion in benzene (6 × 8 cm) B: Area of film after immersion in benzene for 48 hours Table 1 shows the film properties of the polymer latex thus obtained. Sample No. 1, 2, 3, 4,
5, 6, 7, and 8 are examples of the present invention, and 2,2 '
-When azobis (N, N'-alkylenealkylamidine) or its salt is used as a polymerization initiator, the polymer latex produced is atomized and the film formed has good transparency and smoothness. Nos. 6, 6, 7 and 8 have a significantly improved water resistance of the formed film, and the film is insoluble in benzene and has a small degree of swelling and excellent solvent resistance. It can be seen that a so-called cross-linked polymer latex is produced.

 Sample Nos. 9, 10, 11 and 12 are comparative examples.

Example 2 2 parts by weight of glycine betaine chloride polyoxyethylene nonylphenyl ether ester (EO = 3) and 1 part by weight of polyoxyethylene P, P'-isopropylidene diphenyl ether dimethacrylate (EO = 25) were used as emulsifiers, and 2,2 Emulsion polymerization was carried out in the same manner as in Example 1 at the polymerization temperature shown in Table 2 using'-azobis (N, N'-dimethyleneisobutylamine gin) hydrochloride as a polymerization initiator.

Then, in the same manner as in Example 1, the particle size of the produced polymer latex and the characteristics of the formed film were measured. Table 2 shows the results.

Samples Nos. 13 and 14 are examples of the present invention, and it is understood that the temperature at which emulsion polymerization is carried out is preferably 70 ° C or lower. Sample No. 15 is a comparative example.

Example 3 Glycine chloride betaine oxypropylene polyoxyethylene dodecyl phenyl ether ester (PO = 1, EO)
= 3) 2 parts by weight and polyoxypropylene polyoxyethylene P, P'-isopropylidene diphenyl ether diacrylate (PO = 3, EO = 12) 2 parts by weight as an emulsifier, and 2,2 '-(N, N' -Dimethyleneisobutylamidine) hydrochloride as a polymerization initiator, and comprises 60 parts by weight of bityl acrylate, 90 parts by weight of methyl methacrylate, and parts by weight of unsaturated monomers having a reactive functional group shown in Table 3. Emulsion polymerization was carried out in the same manner as in Example 1 using the unsaturated monomer mixture.

Then, the particle size of the polymer latex and the characteristics of the formed film were measured in the same manner as in Example 1. The results are shown in Table 3. Sample Nos. 16, 17, 18, 19, 20, 21, and 22 are examples of this order.

Claims (5)

[Claims] 1. A method for producing an ultrafine-particle polymer latex, which comprises emulsion-polymerizing an ethylenically unsaturated monomer in the presence of an emulsifier using an azo compound as a polymerization initiator at 70 ° C. or lower. 2. The method for producing an ultrafine particle polymer latex according to claim 1, wherein the azo compound is a 2,2′azobis (N, N′-alkylenealkylamidine) compound or a salt thereof. 3. The production of the ultrafine particle polymer latex according to claim 1 or 2, wherein the azo compound is a 2,2'azobis (N, N'-methyleneisobutylamidine) compound or a salt thereof. Method. 4. Production of ultrafine particle polymer latex according to claim 1, 2 or 3, wherein the emulsifier is a polyoxyalkylene ethylenically unsaturated carboxylic acid polyester and / or betaine ester type emulsifier. Method. 5. The ethylenically unsaturated monomer is an unsaturated monomer containing 1 to 10% by weight of an unsaturated monomer having a reactive functional group. , Item 3 or item 4
Item 6. A method for producing an ultrafine-particle polymer latex according to the item.