JPH10245404A - Production of polymer latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To produce a polymer latex in such a way that the amount of fine coagulants in the process of polymerization can be drastically reduced and adhesion of the fine coagulants to the inside wall of a polymerizer vessel and agitator blades is also reduced even in a case of a small quantity of emulsifier in formulation or even in a large-scale polymerizer vessel. SOLUTION: This polymer latex is produced by emulsion polymerization of polymerizable monomers in the presence of a rubbery polymer latex by using a polymerizer vessel comprising an agitator shaft 1, which is located at the center of the polymerizer vessel rotatable from the outside of the vessel, a bottom paddles 2, which are mounted on the near-bottom part of the agitator shaft 1 with the bottom edge kept close to the bottom face of the vessel and have a sweepback angle α of 30-60 deg. at the tip, flat paddles 3 which are mounted on a part upper than the bottom paddles 2 of the agitator shaft 1, have a cross angle β of 40-100 deg. to the bottom paddles, and have plate fins having an edge extending downward, and a plurality of baffle plates arranged along the axial direction from bottom to the top on the side wall of the vessel with a space.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for producing a polymer latex. More specifically, the present invention relates to a method for producing a polymer latex having excellent polymerization stability by using a reaction vessel having a specific stirring blade to suppress the generation of fine coagulation during polymerization.

[0002]

2. Description of the Related Art Conventionally, diene polymer latexes such as polybutadiene latex, styrene-butadiene copolymer latex, acrylonitrile-butadiene copolymer latex, carboxylic acid or vinylpyridine modified styrene-butadiene polymer latex, and the like. Is widely used as a binder for paper coating, fiber treatment or tire cord treatment, and as a rubber component of rubber-reinforced resins. When producing these polymer latexes, the type of the monomer, the polymerization method,
The polymerization prescription is determined by the viscosity at the time of polymerization and the like, but the generation of fine coagulated material at the time of polymerization becomes a problem. This fine coagulated product not only lowers the productivity but also has an adverse effect on the quality of the obtained polymer latex, and various studies have been made to reduce the generation of the fine coagulated product. For example, by increasing the ratio of the polymerization water to the monomer, or by increasing the emulsifier for stabilizing the latex particles, it is possible to reduce the generation of fine coagulated products to some extent. Increasing the content of the polymer, on the contrary, lowers the proportion of the produced polymer, resulting in a reduction in productivity. As a means for improving productivity, the size of a reaction tank is being increased, but it is difficult to obtain a polymer latex having the same performance or structure by simply increasing the capacity of the reaction tank. Further, an increase in the amount of the emulsifier causes various adverse effects due to the emulsifier in the final product, and at present it has not yet reached a fundamental solution.

[0003]

Means for Solving the Problems The present inventors have conducted intensive studies on the above-mentioned problems and, as a result, focused on and studied a stirring blade installed in a polymerization tank. The above-mentioned problems are solved by using a polymerization tank, and even in a polymerization recipe containing a small amount of emulsifier,
Even with a large size of ³ or more, a method for suppressing the generation of fine coagulated products during polymerization and obtaining a polymer latex having excellent polymerization stability was found, and the present invention was completed.

That is, the present invention provides a method for producing a polymer latex obtained by emulsion-polymerizing a polymerizable monomer in the presence of a rubbery polymer latex, wherein the polymerization is carried out using the following polymerization tank. A method for producing a polymer latex is provided. A stirring shaft 1 rotatable from the outside of the tank is provided at the center of the polymerization tank, and the shaft 1 has a lower end close to the bottom wall surface of the stirring tank and a tip end arranged at the bottom of the tank.
Attach the bottom paddle 2 having a receding angle α of 60 °, and have a crossing angle β of 40-100 ° with the bottom paddle 2 above the bottom paddle 2 of the stirring shaft 1 and extend the tip downward. A polymerization tank in which a flat paddle 3 having plate-like fins 4 is mounted, and a plurality of baffle plates 5 extending along the axial direction from the lower part to the upper part are arranged at intervals on the side wall surface of the stirring tank.

Hereinafter, the present invention will be described in detail. Examples of the polymerizable monomer used in the present invention include a conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer,
Aromatic vinyl monomer, vinyl cyanide monomer, unsaturated carboxylic acid alkyl ester monomer, hydroxyalkyl group-containing unsaturated monomer, unsaturated carboxylic acid amide monomer, maleimide monomer And the like.

The conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene, and 2,3-butadiene.
Examples thereof include dimethyl-1,3 butadiene, 2-chloro-1,3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and one or more kinds thereof can be used. In particular, 1,3-butadiene is preferred.

The aromatic vinyl monomers include styrene, α-methylstyrene, methyl α-methylstyrene,
Vinyl toluene and divinyl benzene, and the like,
One or more kinds can be used. Particularly, styrene is preferred.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like, and one or more of them can be used. Acrylonitrile is particularly preferred.

Examples of the ethylenically unsaturated carboxylic acid monomer include mono- or dicarboxylic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. Two or more types can be used. Particularly, mono- or dicarboxylic acids are preferred.

The unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl malate, and dimethyl methacrylate. Examples include itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate, and the like, and one or more kinds can be used. Particularly, methyl methacrylate is preferred.

The unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate and β-hydroxyethyl acrylate.
-Hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate,
Hydroxybutyl acrylate, hydroxybutyl methacrylate, 3-chloro-2-hydroxypropyl methacrylate, di- (ethylene glycol) maleate,
Di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl)
Maleate, 2-hydroxyethyl methyl fumarate and the like can be mentioned, and one kind or two or more kinds can be used. Particularly, β-hydroxyethyl acrylate is preferable.

The unsaturated carboxylic acid amide monomers include:
Acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N,
N-dimethylacrylamide and the like can be mentioned, and one kind or two or more kinds can be used. Acrylamide is particularly preferred.

The maleimide monomers include maleimide, N-phenylmaleimide, N-methylmaleimide,
N-cyclohexylmaleimide and the like can be mentioned, and one kind or two or more kinds can be used. Particularly, N-phenylmaleimide is preferred.

Further, in addition to the above monomers, any of the monomers used in ordinary emulsion polymerization, such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl pyridine, vinyl chloride, and vinylidene chloride, can be used. It is.

The average particle size of the obtained polymer latex is not particularly limited, but is preferably 70 to 300 n.
m. The gel content of the polymer latex is not particularly limited, but is preferably 20 to 90% by weight. Particularly, when the latex is used as a binder for paper coating such as for offset printing paper, the gel content may be reduced. The content is preferably 20 to 60% by weight.

In the present invention, the polymerizable monomer is subjected to emulsion polymerization in the presence of a rubbery polymer latex. As the rubbery polymer latex, for example,
Any rubbery polymer latex such as polybutadiene, styrene-butadiene copolymer, acrylonitrile-butadiene copolymer, ethylene-propylene copolymer, and acrylate copolymer can be used.

As the polymerizable monomer which is polymerized in the presence of the rubbery polymer latex, the monomers exemplified above can be used. In particular, aromatic vinyl monomers and cyanide Use of one or more monomers selected from the group of vinylated monomers, ethylenically unsaturated carboxylic acid monomers, unsaturated carboxylic acid alkyl ester monomers and maleimide monomers Is preferred.

The polymerization tank used for producing the polymer latex of the present invention is shown below. That is, a stirring shaft 1 rotatable from outside the polymerization tank is provided at the center of the polymerization tank.
A bottom paddle 2 having a receding angle α of 30 to 60 ° is attached to the tip arranged at the bottom of the stirring tank so that the lower end thereof is close to the bottom wall of the stirring tank. A flat paddle 3 having a cross angle β of 40 to 100 °, preferably 40 to 70 ° with the bottom paddle 2 and having a plate-like fin 4 extending downward at the tip is attached to the portion, This is a polymerization tank in which a plurality of baffle plates 5 extending in the axial direction from the lower part to the upper part are arranged on the side wall surface at intervals. The baffle plate 5 can be provided with a cooling capacity by allowing cooling water to flow therethrough.

Further, by using the specific polymerization tank specified in the present invention, fine coagulated material during polymerization is reduced as compared with the case where emulsion polymerization is performed using a conventional polymerization tank, Although a latex with excellent stability can be obtained, in the present invention, the effect is particularly remarkable when a polymerization tank having an inner volume of 30 m ³ , preferably 40 m ³ or more is used. . This is not only a laboratory level but also a conventional industrial production scale of 1-20.
It is a remarkably large scale in terms of m ³ , and is very useful for industrial production.

In the present invention, various components (monomer or /
And the method of adding the rubbery polymer latex) are not particularly limited, and any of a batch addition method, a division addition method, and a continuous addition method can be employed. Further, in the present invention, any of single-stage polymerization, two-stage polymerization, multi-stage polymerization and the like can be adopted.

In the emulsion polymerization of the polymer latex of the present invention, usual emulsifiers, polymerization initiators, electrolytes, chain transfer agents, polymerization accelerators, chelating agents and the like can be used.

Examples of the emulsifier include anionic salts such as sulfates of higher alcohols, alkyl benzene sulfonates, alkyl diphenyl ether sulfonates, aliphatic sulfonates, aliphatic carboxylates, and sulfate esters of nonionic surfactants. A surfactant or a nonionic surfactant such as an alkyl ester type, an alkyl phenyl ether type or an alkyl ether type of polyethylene glycol is used alone or in combination of two or more. In addition, the above-mentioned emulsifier causes various adverse effects due to this in the final product, and should be kept as small as possible. Conversely, if the amount used is reduced, the polymerization stability decreases. In the present invention, 1.
Sufficient polymerization stability can be obtained even when the amount is 0 part by weight or less, particularly 0.7 part by weight or less.

As the initiator, a water-soluble initiator such as potassium persulfate, ammonium persulfate, and sodium persulfate, a redox-based initiator, or an oil-soluble initiator such as benzoyl peroxide can be used.

Examples of the chain transfer agent include alkyl mercaptans such as n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-stearyl mercaptan, dimethyl xanthogen disulfide, and diisopropyl xanthogen. Xanthogen compounds such as disulfide, α-methylstyrene dimer, terpinolene, thiuram-based compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetramethylthiuram monosulfide, and 2,6-di-
phenolic compounds such as t-butyl-4-methylphenol and styrenated phenol; allyl compounds such as allyl alcohol; halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, carbon tetrachloride, and carbon tetrabromide;
Benzyloxystyrene, α-benzyloxyacrylonitrile, vinyl ethers such as α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid, thiomalic acid, 2-ethylhexyl thioglycolate, and the like, One type or two or more types can be used.

In the above emulsion polymerization, for example, cyclopentene, cyclohexene, cycloheptene,
The polymerization may be carried out in the presence of a cyclic unsaturated hydrocarbon having one unsaturated bond in the ring such as -methylcyclohexene or 1-methylcyclohexene or a hydrocarbon such as benzene, toluene, hexane or cyclohexane. At this time, the used amount of the hydrocarbon is 0.1 to 30 parts by weight based on 100 parts by weight of the monomer.

The above-mentioned polymer latex containing a conjugated diene monomer as an essential component is, for example, an adhesive for paper coating, an adhesive for carpet backing such as a tufted carpet and a needle punch carpet, and a cushion for automobiles. As an adhesive for rock fiber base materials used for materials, civil engineering mats, industrial filters, etc., wood adhesive used for plywood, decorative materials, etc., and as raw rubber latex used for the production of ABS resin Can be used. In addition, the polymer latex obtained by using the rubbery polymer latex is appropriately collected through a salting-out and drying process, and is recovered as powder or pellets. Can be used.

[Examples] The present invention will be described in more detail below with reference to examples, but the present invention is not limited to these examples unless the gist is changed. In the examples, parts and percentages indicating percentages are based on weight. When a 45 m ³ reaction tank was used, the total of the charged components including water was 43 m ³ . The measurement of various physical properties in Examples and Comparative Examples was based on the following methods.

Polymerization stability Measurement of the amount of coagulated product (the latex was filtered through a 300 mesh wire mesh. The wire mesh was dried in vacuum, and the coagulated material on the wire mesh was weighed.
The weight of the coagulated product per 100 g (solid content) of latex was calculated. ) And the state of adhesion to the stirring blade in the reaction tank were checked, and the polymerization stability was comprehensively judged.

Example 1 Polymerization of Copolymer Latex In a polymerization tank having an internal volume of 45 m ³ shown in FIG.
00 parts, polybutadiene latex (solid content) 60 parts,
Charge 0.3 parts of potassium persulfate and 65 ° C after purging with nitrogen
Then, from that point, a monomer mixture consisting of 28 parts of styrene and 12 parts of acrylonitrile, 0.3 part of t-dodecylmercaptan, and an aqueous emulsifier solution consisting of 0.4 parts of sodium oleate and 20 parts of water were continuously added. The polymerization is performed, and the polymerization is terminated at a polymerization conversion rate of 98%.
Polymer latex F was obtained. The aggregate of the polymer latex F was 0.1 g or less, the adhesion to the tank and the stirring blade was small, and the polymerization stability was very excellent.

[0030]

According to the present invention, by using a polymerization tank having a specific stirring blade specified in the present invention, the amount of fine solidified material can be drastically reduced as compared with the conventional production method, and the amount of the fine coagulated material can be reduced within the polymerization tank to the stirring blade. Can be reduced. Further, it can be produced in a large polymerization tank of 40 m ³ or more, and is industrially very useful.

[Brief description of the drawings]

FIG. 1 is a cutaway perspective view of a polymerization tank provided with a specific stirring blade used in Example 1 of the present invention.

[Explanation of symbols]

Reference Signs List 1 stirring shaft 2 bottom paddle 3 flat paddle 4 plate fin 5 baffle plate α
... Retraction angle of bottom paddle 2, β... Intersection angle between bottom paddle 2 and flat paddle 3.

Claims (2)

[Claims] 1. A method for producing a polymer latex obtained by emulsion-polymerizing a polymerizable monomer in the presence of a rubbery polymer latex, wherein the polymerization is carried out using the following polymerization tank. Production method. A stirring shaft 1 rotatable from the outside of the tank is provided at the center of the polymerization tank, and the shaft 1 has a lower end portion close to the bottom wall surface of the stirring tank and 30 to 60 at the tip arranged at the bottom of the tank. The bottom paddle 2 having the receding angle α is attached, and the bottom paddle 2 and the bottom paddle 2 are mounted at a position above the bottom paddle 2 of the stirring shaft 1 by 40 to 100 °.
And a flat paddle 3 having a plate-like fin 4 having a tip extending downward, and a plurality of baffle plates 5 extending in the axial direction from the lower part to the upper part on the side wall surface of the stirring tank. Polymerization tanks arranged at intervals. 2. The method for producing a polymer latex according to claim 1, wherein a polymerization tank having a capacity of 40 m ³ or more is used.