JPH072911A - Production of copolymer latex, and copolymer latex - Google Patents

Abstract

PURPOSE:To inhibit the occurrence of fine coagulation particles and thereby produce a copolymer latex efficiently with a good polymn. stability. CONSTITUTION:A copolymer latex is produced by subjecting 10-80wt.% aliph. conjugated diene, 0.5-10wt.% ethylenically unsatd. carboxylic acid, and 10-89.5wt.% other copolymerizable monomer to emulsion polymn. in the presence of a specific compd. and a terpene alcohol. A paper coated with a compsn. obtd. from the latex has a good balance among wet pick, dry pick, and printed gloss.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a copolymer latex and a copolymer latex obtained thereby. More specifically, it suppresses the generation of fine coagulation during polymerization, and is a method for producing a copolymer latex that is suitably used as a binder in the fields of paper and carpets, and in particular, it has an excellent balance between adhesive strength and printing gloss, and also has an odor. It relates to a copolymer latex which gives excellent coated paper.

[0002]

BACKGROUND OF THE INVENTION It is well known that a so-called butadiene copolymer latex containing butadiene as a main component is widely used as a binder in the field of paper processing or back sizing of carpets. .

The performance required of the binder in various applications is wide-ranging, and the composition and structure of the butadiene-based copolymer latex is generally changed according to the performance.

These copolymer latexes are generally produced by emulsion polymerization. At this time, a slight difference is observed depending on the composition of the monomer mixture constituting the copolymer latex and the kinds and amounts of various additives. However, there is a problem that a fine coagulated product is generated in the copolymer latex.

Further, in recent years, the speeding up of paper coating and printing has been promoted from the viewpoint of labor saving and rationalization, and a coating color which can withstand high speed coating and a coated paper which can withstand high speed printing have been demanded. Has been.

That is, the coating color is required to have stability against mechanical shear as a performance during coating, and the coated paper is required to have excellent adhesive strength, water resistance and printing gloss.

It is known that the copolymer latex which is one component of the coating color has a great influence on these performances. Fine coagulation in the copolymer latex is known as a factor that impairs the mechanical stability of the coating color.If there is a large amount of such coagulation, streak troubles during blade coating, applicator stains, and stains during calendering can occur. However, problems such as blanket piling during printing occur.

Further, one of the printing effects is the gloss of the printed matter, and one of the methods for improving it is to copolymerize a vinyl cyanide-based monomer such as acrylonitrile so that the ink permeation of the coated paper is appropriately performed. Attempts have been made to suppress this, increase the micro smoothness of the printed surface, and improve the so-called ink gloss.

However, when the proportion of the vinyl cyanide-based monomer is increased, there arises a problem that the adhesive strength of the coating layer on the coated paper is lowered.

Further, these copolymer latexes are
Adhesives for carpet backing such as tufted carpets and needle punched carpets, cushioning materials for automobiles,
It is also used as an adhesive for rock fiber bases used for applications such as civil engineering mats and industrial filters, but even in that case, the fine coagulated substance in the copolymer latex adversely affects the adhesive strength and water resistance. It is affecting.

These copolymer latices often suffer from odors, especially due to the alkyl mercaptans used as chain transfer agents. Since this odor particularly reduces the commercial value of the final product, a copolymer latex with less odor is required.

[0012]

[Means for Solving the Problems] As a result of intensive studies made by the present inventors on the above problems, a copolymer latex formed by emulsion polymerization in the presence of a specific compound has all of these problems. It was found that the copolymer latex can be solved and that the copolymer latex has excellent performance, and the present invention has been completed.

That is, the present invention comprises 10 to 80% by weight of an aliphatic conjugated diene monomer, 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and other monomers copolymerizable therewith. The present invention provides a method for producing a copolymer latex, which comprises subjecting 10 to 89.5% by weight to emulsion polymerization in the presence of a terpene alcohol, and a copolymer latex obtained by the method.

The present invention will be described in detail below.

Examples of the aliphatic conjugated diene-based monomer in the present invention include 1,3-butadiene and 2-methyl-1,3-
Butadiene, 2,3-dimethyl-1,3-butadiene,
2-chloro-1,3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes and the like can be mentioned, and one kind or two or more kinds can be used. Particularly, 1,3-butadiene is preferable.

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. These may be used alone or in combination of two or more.

Other monomers copolymerizable with the above-mentioned aliphatic conjugated diene monomer and ethylenically unsaturated carboxylic acid monomer include alkenyl aromatic monomer and unsaturated carboxylic acid alkyl ester monomer. And unsaturated monomers containing a hydroxyalkyl group, vinyl cyanide monomers, unsaturated carboxylic acid amide monomers and the like.

As the alkenyl aromatic monomer, styrene, α-methylstyrene, methyl α-methylstyrene,
Vinyltoluene and divinylbenzene and the like,
One kind or two or more kinds can be used. Particularly preferred is styrene.

Examples of the unsaturated carboxylic acid alkyl ester monomer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl malate and dimethyl. Itaconate, monomethyl fumarate, monoethyl fumarate, 2-ethylhexyl acrylate and the like can be mentioned, and one kind or two or more kinds can be used. Methyl methacrylate is particularly preferable.

Examples of 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-hydroxyethylmethyl fumarate, etc. are mentioned, and 1 type (s) or 2 or more types can be used. Particularly, β-hydroxyethyl acrylate is preferable.

Examples of vinyl cyanide monomers include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile and α-ethylacrylonitrile.
One kind or two or more kinds can be used. Acrylonitrile is particularly preferable.

As the unsaturated carboxylic acid amide monomer,
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. Particularly preferred is acrylamide.

The above monomer composition comprises 10 to 80% by weight of an aliphatic conjugated diene monomer, 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and other copolymerizable with these. The amount of the monomer is 10 to 89.5% by weight.

If the amount of the aliphatic conjugated diene monomer is less than 10% by weight, the adhesiveness tends to be poor, and if it exceeds 80% by weight, the water resistance tends to be poor.

The ethylenically unsaturated carboxylic acid monomer is 0.5
If it is less than 10% by weight, mechanical stability is poor, and if it exceeds 10% by weight, the viscosity of the latex tends to increase, which is not preferable.

If the amount of the other copolymerizable monomer is less than 10% by weight, the water resistance tends to be inferior, and if it exceeds 89.5% by weight, the adhesiveness tends to be poor.

As the above-mentioned copolymerizable monomer, 3 to 70% by weight of an alkenyl aromatic monomer and 1 to 40% by weight of an unsaturated carboxylic acid alkyl ester monomer and / or a vinyl cyanide monomer are used. It is preferable to use in the range of.

Examples of the terpene alcohol used in the present invention include citronell, geraniol, linalool and terpineol, and one or more of them can be used.

The amount of these terpell alcohols used is not particularly limited and can be appropriately adjusted according to the performance required for the copolymer latex, but is preferably 0. 0 based on 100 parts by weight of the monomer mixture. It is 1 to 20% by weight.

If the amount is less than 0.1% by weight, the object of the present invention cannot be achieved, and if the amount exceeds 20% by weight, the improvement effect is saturated and the economy is disadvantageous.

The method of adding various components in the present invention is not particularly limited, and any of a batch addition method, a divided addition method and a continuous addition method can be adopted. Further, in the emulsion polymerization, a commonly used emulsifier, polymerization initiator, chain transfer agent, electrolyte, polymerization accelerator, chelating agent and the like can be used.

In the present invention, any one-step polymerization, two-step polymerization, multi-step polymerization, power feed polymerization method or the like may be adopted.

Examples of emulsifiers include anionic salts such as sulfuric acid ester salts of higher alcohols, alkylbenzene sulfonates, alkyldiphenyl ether sulfonates, aliphatic sulfonates, aliphatic carboxylates, and sulfuric acid ester salts of nonionic surfactants. Surfactants or nonionic surfactants such as alkyl ester type of polyethylene glycol, alkyl phenyl ether type, alkyl ether type and the like are used in one kind or in two or more kinds.

As the initiator, water-soluble initiators such as potassium persulfate, ammonium persulfate and sodium persulfate, redox type initiators or oil-soluble initiators 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, dimethylxanthogen disulfide, diisopropylxanthogen. Xanthogen compounds such as disulfide, α-methylstyrene dimer, terpinolene, tetramethylthiuram disulfide,
Thiuram compounds such as tetraethylthiuram disulfide and tetramethylthiuram monosulfide, phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, dichloromethane and dibromomethane. , Halogenated hydrocarbon compounds such as carbon tetrachloride, carbon tetrabromide, α
-Vinyl ether such as benzyloxystyrene, α-benzyloxyacrylonitrile, α-benzylacrylamide, triphenylethane, pentaphenylethane,
Acrolein, methacrolein, thioglycolic acid,
2-ethylhexyl thioglycolate and the like are mentioned, and 1
One kind or two or more kinds can be used.

The amount of the chain transfer agent used is not particularly limited and can be appropriately adjusted according to the performance required for the copolymer latex, but preferably 0.05 to 100% by weight of the monomer mixture. 10% by weight is used.

By adopting the manufacturing method of the present invention,
It is possible to suppress the generation of fine coagulated substances and obtain a latex having good polymerization stability.

The copolymer latex obtained by the production method of the present invention may be blended with a pigment or the like, if necessary, to give, for example, a paper coating composition, a carpet backing adhesive composition, or a rock fiber base material. It can be used as an adhesive composition for tires, an adhesive composition for tire cords, an adhesive composition for woods, an adhesive composition for leathers, and the like.

When the copolymer latex of the present invention is applied to a paper coating composition, it is possible to obtain a coated paper having a particularly good balance of adhesive strength and printing gloss and excellent odor.

To prepare this paper coating composition, 2 to 100 parts by weight, preferably 5 to 30 parts by weight of the copolymer latex of the present invention is used per 100 parts by weight of the pigment in terms of solid content. 0 to 30 parts by weight of the binder can be used.

Here, as the pigment, kaolin clay,
Talc, barium sulfate, titanium oxide, calcium carbonate,
Examples thereof include inorganic pigments such as aluminum hydroxide, zinc oxide and satin white, and organic pigments such as polystyrene latex, which may be used alone or in combination.

As other binders, modified starch such as starch, oxidized starch, esterified starch, natural binder such as soybean protein and casein, or synthetic latex such as polyvinyl alcohol, polyvinyl acetate latex and acrylic latex. Is used.

To prepare the paper coating composition of the present invention,
Further other auxiliary agents such as dispersants (sodium pyrophosphate, sodium polyacrylate, sodium hexametaphosphate, etc.), antifoaming agents (polyglycol, fatty acid ester, phosphate ester, silicone oil, etc.), leveling agents (funnel oil, Dicyandiamide, urea, etc.),
Preservatives, water resistance agents (formalin, hexamine, melamine resins, urea resins, glyoxal, etc.), mold release agents (calcium stearate, paraffin emulsion, etc.), fluorescent dyes, color water retention improvers (carboxymethyl cellulose, sodium alginate, etc.) It is added as needed.

Further, the method for applying the paper coating composition to the coated paper is known in the art, for example, an air knife coater,
It is carried out by a coating machine such as a blade coater, a roll coater or a bar coater. After coating, the surface is dried and finished by calendering.

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 as long as the gist thereof is not exceeded. In the examples, parts and percentages are based on weight. The physical properties in the examples were measured by the following methods.

Staining of the reactor After polymerization, the deposits on the inner wall of the reactor were visually observed. ◯: Very low Δ: Low ×: High

The amount of fine coagulated substance of several μm to 50 μm was observed by a microbial coagulated substance microscope. ◯: Very low Δ: Few ×: High Evaluated in three stages.

A latex film is prepared by drying the gel content at room temperature. Then accurately weigh about 1.0 g of latex film, put in 400 cc of toluene, leave it for 48 hours to dissolve, filter through a 300-mesh wire net, dry it, and measure the toluene insoluble content (gel) on the wire net to determine the gel content. calculate.

RI Wet Pick The degree of picking when printed with dampening water with a RI printing machine is judged with the naked eye, and five grades from 1st grade (the best one) to 5th grade (the worst) Evaluated by law. The average value of 6 times is shown.

Evaluation was performed in the same manner as in the RI Wet Pick, except that RI Dry Pick dampening water was not used.

Printing Gloss Using an RI printing machine, printing was performed once using a certain amount of commercially available red ink for offset printing, and the printing surface of the coated paper was measured with a Murakami gloss meter at an incident angle of 75 ° C. and a reflection angle of 75. Measure at ° C.
The larger the printing gloss value, the better.

A coated paper was obtained in the same manner as the above coating method except that the coating amount of the odorous paper coating composition was 20 g / m ^{2 on} one side. A test piece of 10 cm x 10 cm is prepared from the obtained coated paper, and the three test pieces are placed in a glass bottle that can be sealed and left at 50 ° C for 1 hour, and then the plug is removed to determine the degree of odor. did. ○: Smelling △: Slightly smelling ×: Almost no smell

Preparation of copolymer latex In a 10 liter autoclave, 100 parts by weight of water, 0.3 part of sodium dodecylbenzenesulfonate, 0.2 part of sodium hydrogen carbonate, 1.0 part of potassium persulfate and 1.0 part are shown. The first-stage monomer mixture, chain transfer agent, and terpene alcohol were charged and the first-stage polymerization was carried out at 65 ° C. When the conversion of the first-stage emulsion polymerization reached 70%, the second-stage monomer mixture and the chain transfer agent were continuously added to the terpene alcohol for 7 hours to carry out the second-stage polymerization. Then, in order to complete the polymerization, the reaction was continued for another 3 hours to complete the polymerization at a conversion of 98%. The copolymer latex thus obtained was adjusted to pH 7 with sodium hydroxide, and then unreacted monomers were removed by steam distillation to obtain a copolymer latex 1
~ 8 was obtained. The results are shown in Table-1.

In the table, the amount on the left side is the amount of the first step and the right side is the amount of the second step across "/".

Preparation of Paper Coating Composition Copolymer latices 1 to 8 were respectively adjusted with pure water so as to have a solid content concentration of 60% based on the following formulation to obtain a paper coating composition. .

(Prescription) Kaolin clay 80 parts Calcium carbonate 20 parts Modified starch 8 parts Copolymer latex 12 parts (solid content)

Further, commercially available high-quality paper (64 g / m ² ) was coated and dried using a coating bar so that the coating amount of the above composition was 10 g / m ^{2 on} one side, and then the roll temperature was 5
Super calendering was performed under conditions of 0 ° C. and linear pressure of 70 to 80 kg / cm ² to obtain coated paper. The resulting coated paper was measured for RI Wet Pick, RI Dry Pick, print gloss and odor. The results are shown in Table-2.

[0058]

[Table 1]

[0059]

[Table 2]

Claims (2)

[Claims] 1. An aliphatic conjugated diene-based monomer 10 to 80 parts by weight, an ethylenically unsaturated carboxylic acid monomer 0.5 to 10 parts by weight, and another monomer 10 to be copolymerizable therewith. 8
A method for producing a copolymer latex, which comprises emulsion-polymerizing 9.5% by weight in the presence of a terpene alcohol. 2. A copolymer latex obtained by the method according to claim 1.