JP2996419B2 - Emulsion polymerization stabilizer - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a stabilizer for emulsion polymerization comprising a polymer having a polyvinyl alcohol polymer in a side chain. Emulsions prepared using the stabilizers are particularly excellent in chemical stability and mechanical stability, and are therefore used in the fields of adhesives and paints.

[0002]

2. Description of the Related Art A polyvinyl alcohol polymer is widely used as a stabilizer for emulsion polymerization of a vinyl ester monomer represented by vinyl acetate. An emulsion using the polymer has excellent chemical stability and mechanical stability, and a film obtained from the emulsion becomes a tough film having high mechanical strength. However, when a polyvinyl alcohol polymer is used as a protective colloid,
The difficulty in controlling the particle size, especially the inability to produce small particle size emulsions, the high viscosity of the emulsion, the poor water resistance of the film from the emulsion, sufficient for emulsions other than vinyl esters It is also a well-known fact that problems such as inability to obtain high polymerization stability occur, and a stabilizer for emulsion polymerization that has the characteristics of a polyvinyl alcohol-based polymer protective colloid emulsion and solves the above problems has been developed. Was sought.

[0003]

SUMMARY OF THE INVENTION An object of the present invention is not limited to vinyl ester polymers, but it can be used as a stabilizer for emulsion polymerization of various polymer emulsions. Another object of the present invention is to provide a stabilizer for emulsion polymerization, which solves the above-mentioned problems of the protective colloid while maintaining the above.

[0004]

Means for Solving the Problems The present inventors have conducted intensive studies to solve the above-mentioned problems, and as a result, have found that polyvinyl alcohol
Polymerize macromolecules or polymer
After polymerizing the phenyl ester polymer macromonomer,
The present inventors have found a stabilizer for emulsion polymerization comprising a polymer having a polyvinyl alcohol-based polymer in a side chain obtained by solvent decomposition or hydrolysis, and have completed the present invention.

The polymer which is the dispersion stabilizer for emulsion polymerization of the present invention has a side chain of a polyvinyl alcohol polymer [I] having a vinyl alcohol content of 50 mol% or more and a number average polymerization degree of 3 to 500. Polymer [A]. Here, the structure of the main chain of the polymer [A] and the structure of the portion connecting the side chain to the main chain are not particularly limited, and examples thereof include a vinyl polymer and a condensation polymer. Examples of these polymers include a homopolymer or copolymer of a macromonomer having a polyvinyl alcohol-based polymer in a side chain, and polyvinyl ester.
Homopolymer or copolymer of macromonomer
It is useful polymer obtained by solvolysis or hydrolysis body, methacrylic acid esters, acrylic acid esters, methacrylamide, acrylamide, polymers of a vinyl-type structure, such as styrene, are used in preference.

The polyvinyl alcohol-based polymer [I] constituting the side chain of the polymer [A] is a water-soluble polymer [A],
Affects water dispersibility and dispersion stabilization ability. The vinyl alcohol content must be 50 mol% or more from the viewpoint of water solubility, water dispersibility and dispersion stabilizing ability.
Molar% or more is preferred. The number average polymerization degree of the polyvinyl alcohol-based polymer [I] affects the dispersion stabilizing ability and the properties of the obtained aqueous dispersion of the pigment, and needs to be 3 to 500, preferably 10 to 300. And more preferably 10 to 200. If the degree of polymerization of the polyvinyl alcohol-based polymer [I] is too low, the dispersion stabilizing ability is reduced, and if it is too high, the properties of the polyvinyl alcohol-based polymer may be too strong. The content of the unit containing the polymer [I] in the polymer [A] affects water solubility, water dispersibility and dispersion stabilizing ability, and is 10 to 100% by weight, preferably 15 to 100% by weight, If the content of the unit containing the polymer [I] is too low, the desired performance may not be obtained. The unit other than the vinyl alcohol unit constituting the polymer [I] may be contained in an amount of less than 50 mol% according to the purpose.

[0007] Examples of such a unit include the following units. That is, ethylene, propylene, 1-
Butenes, olefins such as isobutene, vinyl acetate, vinyl formate, vinyl propionate, vinyl butyrate, vinyl pivalate, vinyl esters such as vinyl versatate, vinyl laurate, vinyl stearate, vinyl benzoate, acrylic acid and Its salts, methyl acrylate, ethyl acrylate, n-propyl acrylate, i-propyl acrylate, n-butyl acrylate, i-butyl acrylate, t-butyl acrylate, 2-acrylate acrylate
Ethylhexyl, dodecyl acrylate, acrylates such as octadecyl acrylate, methacrylic acid and its salts, methyl methacrylate, ethyl methacrylate,
Methacrylates such as n-propyl methacrylate, i-propyl methacrylate, n-butyl methacrylate, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, Acrylamide,
N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide, diacetone acrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or quaternary salts, N-methylolacrylamide and its derivatives, etc. Acrylamide derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidopropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts or quaternary salts thereof, N-methylolacrylamide and its derivatives, etc. Methacrylamide derivatives, methyl vinyl ether, ethyl vinyl ether,
vinyl ethers such as n-propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether and stearyl vinyl ether; nitriles such as acrylonitrile and methacrylonitrile; vinyl chloride; vinylidene chloride , Vinyl fluoride, vinyl halides such as vinylidene fluoride, allyl acetate,
Allyl compounds such as allyl chloride; maleic acid and its salts or esters; itaconic acid and its salts or esters; vinylsilyl compounds such as vinyltrimethoxysilane;

Preferred examples of the polymer [A] of the present invention include a homopolymer or copolymer of a polyvinyl alcohol polymer macromonomer. Polymer [A]
Is a copolymer, the structural unit other than the unit containing the polymer [I] is selected depending on the purpose of adjusting the hydrophilicity or hydrophobicity of the polymer [A], imparting ionicity, and the like. The type and amount of the structural unit are not particularly limited as long as it is within the above range, and for example, the following units are exemplified. That is, ethylene, propylene, 1-butene, olefins such as isobutene, methyl acrylate, methacrylic acid and salts thereof, methyl methacrylate, ethyl methacrylate, n-propyl methacrylate, i-propyl methacrylate, n-methacrylate Butyl, i-butyl methacrylate, t-butyl methacrylate, 2-ethylhexyl methacrylate, dodecyl methacrylate, octadecyl methacrylate, 2-hydroxyethyl methacrylate, 2-dimethylaminoethyl methacrylate and salts or quaternary salts thereof Methacrylates such as 2-diethylaminoethyl methacrylate and its salts or quaternary salts, (2-hydroxy) dimethylaminopropyl methacrylate, 3-trimethoxysilylpropyl methacrylate, styrene, p-meth Styrene, α-methylstyrene, chloromethylstyrene, p-styrenesulfonic acid and salts thereof, styrenes such as p-hydroxystyrene and derivatives thereof, acrylamide, N-methylacrylamide, N-ethylacrylamide, N, N-dimethylacrylamide , Diacetone acrylamide, acrylamidopropanesulfonic acid and its salts, acrylamidopropyldimethylamine and its salts or quaternary salts thereof,
Acrylamide derivatives such as N-methylolacrylamide and its derivatives, methacrylamide, N-methylmethacrylamide, N-ethylmethacrylamide, methacrylamidepropanesulfonic acid and its salts, methacrylamidopropyldimethylamine and its salts or quaternary, N Methacrylamide derivatives such as methylol methacrylamide and derivatives thereof, N-vinylpyrrolidone, methyl vinyl ether, ethyl vinyl ether, n
-Propyl vinyl ether, i-propyl vinyl ether, n-butyl vinyl ether, i-butyl vinyl ether, t-butyl vinyl ether, dodecyl vinyl ether, vinyl ethers such as stearyl vinyl ether, acrylonitrile, nitriles such as methacrylonitrile, vinyl chloride, vinylidene chloride, Vinyl fluoride, vinyl halides such as vinylidene fluoride, allyl acetate,
Allyl compounds such as allyl chloride and allyl alcohol, maleic anhydride, maleic acid and its salts or esters, fumaric acid and its salts or esters, itaconic acid and its salts or esters, and the like, isopropenyl acetate, N-vinylimidazole And the like. Furthermore, examples of these constituent units include macromonomers such as polyoxyalkylene, polyoxyalkylene phosphate, polystyrene, polymethyl methacrylate, and polysiloxane.

The polymer [A] constituting the stabilizer for emulsion polymerization of the present invention can be synthesized by several methods, but is synthesized by homopolymerization or copolymerization of a polyvinyl alcohol polymer macromonomer, or a polyvinyl acetate polymer. A method of hydrolyzing a homopolymer or a copolymer of a polyvinyl ester-based polymer macromonomer such as a polymer macromonomer is preferable from the viewpoint of controlling the composition and structure of the polymer [A]. Here, the structure of the polyvinyl alcohol-based polymer macromonomer or the polyvinyl acetate-based polymer macromonomer is not particularly limited, and the structure of the unsaturated double bond portion is excellent in radical polymerizability, such as methacrylamide, acrylamide, Methacrylic acid esters and those having a styrene structure are preferably used, especially methacrylic acid amides,
A macromonomer having an acrylamide or methacrylic ester structure is particularly preferably used. The polymerization of the macromonomer and the subsequent solvolysis or hydrolysis are carried out in a conventional manner.

[0010] The dispersion stabilizer for emulsion polymerization of the present invention is not limited to a stabilizer for emulsion polymerization of vinyl esters such as vinyl acetate. Examples thereof include acrylic esters, methacrylic esters, styrene or derivatives thereof, and conjugated dienes. Can be widely used as a stabilizer for emulsion polymerization of a monomer capable of radical polymerization, and an emulsion having a particularly small particle diameter can be stably obtained. The amount of the emulsion polymerization stabilizer to be used is usually 1 to the polymer in the obtained emulsion.
The amount is preferably from 20 to 20% by weight, and more preferably from 2 to 10% by weight. When the amount is less than this, stability cannot be sufficiently maintained. The stabilizer for emulsion polymerization of the present invention, within a range that does not impair the purpose of the present invention,
An ordinary low-molecular emulsifier or high-molecular stabilizer can be used in combination.

[0011]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited thereto. In the Examples, "parts" and "%" represent "parts by weight" and "% by weight", respectively, unless otherwise specified.

Reference Example 1 Synthesis of polyvinyl acetate macromonomer A reactor equipped with a stirrer, a reflux condenser and a dropping funnel was charged with a polyvinyl acetate 60 having a 2-hydroxythio group at one end and a number average degree of polymerization of 31. , 40 parts of toluene and 4.16 parts of pyridine, and stirred well at room temperature.
While the reactor was stirred at room temperature, 5.50 parts of methacrylic acid chloride distilled immediately before and 10 parts of dehydrated toluene were mixed well, and the mixture was uniformly added dropwise over 1 hour by a dropping funnel. After completion of the dropwise addition, stirring was continued at room temperature for another 3 hours. Next, 1.70 parts of methanol was added, and the mixture was stirred for 1 hour. Toluene and methanol were distilled off at 40 ° C. under reduced pressure at 400 ° C. while adding 400 parts of toluene in four portions. The product was removed by filtration to obtain a 53.2% toluene solution of the polymer. A part of this toluene solution was put into n-hexane to recover the polymer, which was reprecipitated and purified twice with acetone-hexane, and then dried at 40 ° C under reduced pressure. Proton NMR of this purified polymer was measured using CDCl ₃ as a solvent and was found to be a polyvinyl acetate macromonomer having a number average polymerization degree of 31 and having a methacrylic ester structure at one end. Subsequently, the operation of distilling off toluene under reduced pressure and further adding and distilling off methanol was repeated to remove toluene, thereby obtaining a 60.3% methanol solution of a polyvinyl acetate macromonomer.

REFERENCE EXAMPLE 2 100 parts of a methanol solution (concentration: 60.3%) of the polyvinyl acetate macromonomer obtained in Reference Example 1 was placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer. It was charged and replaced with nitrogen by bubbling nitrogen gas at room temperature.
The temperature of the reactor was raised, and when the internal temperature reached 60 ° C., 0.24 part of 2,2-azobisisobutyronitrile was dissolved in 20 parts of methanol, and an initiator solution purged with nitrogen was added, followed by polymerization. Started. After the polymerization was continued under stirring for 20 hours, the polymerization was stopped by cooling, followed by methanol 60.3
Was added and the temperature was adjusted to 40 ° C. Sodium hydroxide 1
28 parts of a 0% methanol solution was added, and methanol decomposition reaction was carried out. After the system was gelled, the system was pulverized, 50 parts of methanol was added, and the mixture was left at room temperature for 24 hours to complete the reaction. Subsequently, 30 parts of methyl acetate and 5 parts of water were added and the mixture was heated to 50 ° C.
, And then purified by Soxhlet washing with methanol, and a polymer having a number average degree of polymerization of 31 and having a polyvinyl alcohol-based polymer [I] in the side chain (Polymer [A] -1)
And). The polymer in the homopolymer of polyvinyl alcohol macromonomer, H of d _6-DMSO solution ¹ -
From the NMR measurement, the vinyl alcohol content of the polyvinyl alcohol-based polymer was 99.0 mol%.

Reference Examples 3 to 9 Number average degree of polymerization of 60 to 1 synthesized in the same manner as in Reference Example 1.
A homopolymer or copolymer of a polyvinyl acetate-based macromonomer obtained by polymerization using the polyvinyl acetate-based macromonomer of Example 20 in the same manner as in Reference Example 2 was prepared in accordance with the method described in Reference Example 2. And solvolysis to obtain polymers ([A] -2 to [A] -8) having various polyvinyl alcohol-based polymers in their side chains. Table 1 shows the results.

[Table 1]

Examples 1 to 8 Polymers [A] -1 to [A] obtained in the above Reference Example were placed in a reactor equipped with a stirrer, a reflux condenser, a nitrogen inlet tube and a thermometer.
-8 is measured in a predetermined amount, 100 parts of distilled water is added,
The mixture was heated and stirred at ℃ to dissolve. The mixture was cooled to room temperature while flowing nitrogen gas, and 50 parts of a monomer for emulsion polymerization was added and heated. When the internal temperature reached a predetermined temperature, the polymerization initiator was separately dissolved in 20 parts of distilled water, and an aqueous initiator solution prepared by purging with nitrogen was added to initiate polymerization. After completion of the polymerization, the mixture was cooled to room temperature to obtain an emulsion. In the case of copolymerization of ethylene and butadiene, a pressure-resistant reactor was used. The polymerization recipe and the polymerization result are shown in Tables 2 and 3, respectively.

Comparative Examples 1 and 2 Emulsion polymerization was carried out in the same manner as in Examples 1 to 3, except that PVA-205 (manufactured by Kuraray Co., Ltd., polymerization degree: 500, saponification degree: 88%) was used as a polymerization stabilizer. The polymerization recipe and the polymerization result are shown in Tables 2 and 3, respectively.

[Table 2]

[Table 3]

[0017]

The stabilizer for emulsion polymerization of the present invention can be used as a stabilizer for emulsion polymerization of various monomers due to the variety of structures and compositions, and the effect is clear from Examples and Comparative Examples. is there.

Claims (1)

(57) [Claims] 1. Polyvinyl alcohol polymer macromo
Nomer polymerization or polyvinyl ester polymerization
After polymerizing the macromolecule, solvolysis or hydrolysis
Decomposition, vinyl alcohol content is 50 mol%
An emulsion polymerization stabilizer comprising a polymer having a side chain of a polyvinyl alcohol polymer having a number average polymerization degree of 3 to 500 as described above.