JP2961208B2 - Method for producing copolymer latex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel method for producing a copolymer latex. More specifically, the present invention relates to a method for producing a copolymer latex suitably used as a binder in the paper processing field or carpet backsizing.

[0002]

2. Description of the Related Art It is well known that butadiene-based copolymer latex containing butadiene as a main component is widely used as a binder in the paper processing field, carpet back sizing, and the like.

[0003] Coated papers obtained by using these copolymer latexes as binders in the paper processing field are used in various applications because of their excellent adhesive strength, water resistance, gloss and the like. However, in recent years, in the printing process, speeding up of printing has been promoted in order to improve productivity. Therefore, coated papers are required to have better adhesive strength and blister resistance. The blister resistance and the adhesive strength of the coated paper are mutually contradictory performances, and it is an urgent task in this field to simultaneously satisfy these two performances. For this reason, improvement of the above-mentioned copolymer latex has been conventionally studied to solve this problem, but none of these conventional copolymer latexes has been sufficiently satisfactory.

Further, these copolymer latexes are:
Adhesives for carpet backing such as tufted carpets and needle punch carpets and car cushion materials,
It is also used as an adhesive for rock fiber base materials used in applications such as civil engineering mats and industrial filters. In these applications, a copolymer latex having sufficient adhesive strength is required.

[0005]

As described above, in the conventional copolymer latex, the adhesive strength and blister resistance required with the recent increase in printing speed cannot be said to be sufficient.
Further, the adhesive strength required for other uses is not sufficient.

[0006]

Means for Solving the Problems The inventors of the present invention have conducted intensive studies on the above problems, and as a result, when performing emulsion polymerization in the presence of a specific compound, a part of the chain transfer agent was converted to a monomer. It has been found that the above-mentioned problems can be solved by adding after the addition, and the present invention has been achieved.

That is, according to the present invention, one unsaturated bond is contained in a ring.
In the presence of one cyclic unsaturated hydrocarbon, the aliphatic conjugated diene-based monomer, ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith are subjected to emulsion polymerization. An object of the present invention is to provide a method for producing a copolymer latex, which comprises adding a part of a transfer agent after completion of addition of a monomer.

Hereinafter, the present invention will be described in detail.

The aliphatic conjugated diene monomer in the present invention includes 1,3-butadiene and 2-methyl-1,3-
Butadiene, 2,3-dimethyl-1,3-butadiene,
Examples thereof include 2-chloro-1,3-butadiene, substituted linear conjugated pentadienes, substituted and side chain conjugated hexadienes, and one or more kinds can be used. In particular, 1,3-butadiene is preferred.

[0010] 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.

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

The alkenyl aromatic monomer includes 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.

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, 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.

Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate, β
-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.

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

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.

Further, in addition to the above-mentioned monomers, fatty acid vinyl esters such as vinyl acetate and vinyl propionate;
Basic monomers such as aminoethyl (meth) acrylate, dimethylaminoethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-vinylpyridine, and 4-vinylpyridine, vinyl chloride, vinylidene chloride, and the like can be used. it can.

The above monomer composition is not particularly limited,
It is preferably 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 10 to 89.5% by weight of another monomer copolymerizable therewith. .

If the amount of the aliphatic conjugated diene monomer is less than 10% by weight, the adhesiveness tends to be poor. If the amount of the ethylenically unsaturated carboxylic acid monomer is less than 0.5% 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. 10 other copolymerizable monomers
If the amount is less than 8% by weight, the water resistance tends to be poor.

The chain transfer agent used in the present invention includes:
n-hexyl mercaptan, n-octyl mercaptan, t-octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n-stearyl mercaptan and other alkyl mercaptans, xanthogen compounds such as dimethyl xanthogen disulfide, diisopropyl xanthogen disulfide, and α- Methylstyrene dimer, terpinolene, tetramethylthiuram disulfide, tetraethylthiuram disulfide,
Thiuram compounds such as tetramethylthiuram monosulfide, phenol compounds such as 2,6-di-t-butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, dichloromethane, dibromomethane, carbon tetrachloride , Halogenated hydrocarbon compounds such as carbon tetrabromide, vinyl ethers such as α-benzyloxystyrene, α-benzyloxyacrylonitrile, α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid Thiomalic acid, 2-ethylhexyl thioglycolate, and the like, and one or more kinds can be used.

The use amount of these chain transfer agents is not limited at all, and can be appropriately adjusted according to the performance required for the copolymer latex, but is preferably 0.05 to 100 parts by weight based on 100 parts by weight of the monomer mixture. 10 parts by weight.

In the present invention, it is necessary to add a part of the above chain transfer agent after the completion of the addition of the monomer. If the entire amount of the chain transfer agent is added before the end of the monomer addition, the balance between the blister resistance and the adhesive strength, which is the object of the present invention, is not preferable, and is not preferable. Further, the ratio of the chain transfer agent added after completion of the monomer addition to the total amount of the chain transfer agent used is not particularly limited, but is preferably 30% by weight or less.

The cyclic unsaturated hydrocarbon having one unsaturated bond in the ring used in the present invention has a boiling point of 140 ° C. or lower, since it is necessary to recover an unreacted product after the polymerization. preferable. Specific examples include cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, 1-methylcyclohexene and the like.

The amount of the compound used in the present invention is 0.1 to 30 parts by weight based on 100 parts by weight of the monomer mixture. If the amount is less than 0.1 part by weight, the effect of the present invention is insufficient, and if the amount exceeds 30 parts by weight, the amount of the compound remaining as an unreacted substance also relatively increases, and the energy required for the recovery increases. Not preferred. Preferably 0.5
１５15 parts by weight.

The method of adding the various components in the present invention is 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 emulsion polymerization, a commonly used emulsifier, polymerization initiator, electrolyte, polymerization accelerator, chelating agent and the like can be used.

In the present invention, one-stage polymerization, two-stage polymerization or multi-stage polymerization can be employed, but emulsion polymerization is particularly preferred in the following manner.

That is, in the first stage, 3 to 40% by weight, preferably 5 to 30% by weight, of a monomer or a part of the monomer and a chain transfer agent is added to all monomers. Polymerized,
When the polymerization conversion of the first stage becomes 50% or more, the remaining monomer or the monomer of the second stage and a part of the chain transfer agent are added as a second stage, and the polymerization is carried out. After completion of the addition of the eye monomer, a part of the chain transfer agent is further added to continue the polymerization,
Substantially complete the polymerization.

Examples of the emulsifier include anionic surfactants such as sulfates of higher alcohols, alkylbenzene sulfonates, aliphatic sulfonates, aliphatic carboxylates, sulfates of nonionic surfactants, and polyethylene glycol. Nonionic surfactants such as alkyl ester type, alkyl phenyl ether type and alkyl ether type are used alone or in combination of two or more.

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.

By adopting the above-mentioned production method, it is possible to obtain a copolymer latex which provides a coated paper having an excellent balance between adhesive strength and blister resistance. In the present invention, the cyclic unsaturated hydrocarbon having one unsaturated bond is not preferable in terms of working environment hygiene in the final use. The compound is substantially removed (0.5 parts by weight or less, more preferably 0.1 parts by weight or less based on 100 parts by weight of the copolymer latex (solid content)).

Known methods for removing the compound include:
For example, it can be removed by steam distillation, vacuum distillation, or blowing of an inert gas.

The copolymer latex obtained by the above-mentioned production method can be used as a paper coating paint together with a pigment, other binders and auxiliaries as a binder, and is obtained by applying the paint. The obtained coated paper is excellent in balance between adhesive strength and blister resistance. Further, the copolymer latex can be used not only for paper coating but also as a binder for carpet backing, rock fiber base material, tire cord, wood, leather and the like.

[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 it exceeds the gist thereof. In the examples, parts and percentages indicating percentages are based on weight. The measurement of various physical properties in the examples was based on the following methods.

RI Wet Pick The degree of picking when printing with a fountain solution on a RI printing machine is visually judged, and five grades from the first grade (best) to the fifth grade (worst). It was evaluated by the method. The average value of 6 times is shown.

The evaluation was performed in the same manner as in the above-mentioned RI Wet Pick except that the RI Dry Pick dampening solution was not used.

Blister resistance The minimum temperature at which blistering occurs when the double-sided printing coated paper is humidified (about 6%) and thrown into a heated oil bath.

Preparation of Copolymer Latex In a 10 liter autoclave, 100 parts by weight of water, 0.4 part of sodium dodecylbenzenesulfonate, 0.3 part of sodium hydrogen carbonate, 1.0 part of potassium persulfate and Table 1 or Table 2 were prepared. The first-stage polymerization was carried out at 65 ° C. by charging the first-stage monomer mixture shown in 2, a chain transfer agent, and a cyclic unsaturated hydrocarbon having one unsaturated bond in the ring. When the conversion of the first-stage emulsion polymerization reached 65%, the second-stage monomer mixture, the chain transfer agent, and the unsaturated hydrocarbon were continuously added in 7 hours, and the second-stage polymerization was performed. . After the completion of the second-stage monomer addition, a chain transfer agent and an unsaturated hydrocarbon were continuously added over 2 hours, and then polymerization was continued until the polymerization conversion reached 97%, and the polymerization was terminated. After adjusting the pH of the obtained copolymer latex to 8 using sodium hydroxide, unreacted monomers and unsaturated hydrocarbons remaining as unreacted substances were removed by steam distillation. ~ I and a
~ D.

In the table, the amount after the addition of the monomer in the first stage on the left, the middle in the second stage, and the right in the second stage is shown with "//" interposed therebetween.

Preparation of Paper Coating Coating (I) Each of the copolymer latexes A to C and a to b was adjusted with pure water so as to have a solid content of 62% based on the following formulation. A paint for paper coating was obtained.

(Formulation I) Kaolin clay 80 parts Heavy calcium carbonate 20 parts Modified starch 5 parts Copolymer latex 12 parts (solid content) ６２ 62% solids

Further, after coating and drying a commercially available high-quality paper (64 g / m ² ) with a coating bar so that the coating amount of the above composition is 13 g / m ^{2 on} one side, the roll temperature is adjusted to 50 g / m ^2.
A super calender treatment was performed at 70 ° C. and a linear pressure of 70 to 80 kg / cm 2 to obtain a coated paper. The obtained coated paper was measured for RI Wet Pick, RI Dry Pick, and blister resistance.

Preparation of Paper Coating Coating (II) Copolymer latexes D to I and c to d were respectively adjusted to have a solid content of 62% based on the following formulation using pure water. A paint for paper coating was obtained.

(Formulation II) Kaolin clay 60 parts Heavy calcium carbonate 40 parts Modified starch 6 parts Copolymer latex 10 parts (solid content) ６２ 62% solids

After coating and drying a commercially available high-quality paper (64 g / m ² ) using a coating bar so that the coating amount of the above composition is 10 g / m ^{2 on} one side, a roll temperature of 50 g / m ² was obtained.
A super calender treatment was performed at 70 ° C. and a linear pressure of 70 to 80 kg / cm 2 to obtain a coated paper. The obtained coated paper was measured for RI Wet Pick, RI Dry Pick, and blister resistance.

Table 3 shows the results.

[0046]

[Table 1]

[0047]

[Table 2]

[0048]

[Table 3]

[0049]

By using the copolymer latex obtained in the present invention as a binder for paper coating, a coated paper excellent in adhesive strength and blister resistance can be obtained. In other applications such as backsizing, a final product having excellent adhesive strength can be obtained.

Claims (1)

(57) [Claims] An aliphatic conjugated diene-based monomer in the presence of a cyclic unsaturated hydrocarbon having one unsaturated bond in a ring selected from cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene and 1-methylcyclohexene. When emulsion polymerization of the monomer, the ethylenically unsaturated carboxylic acid monomer and other monomers copolymerizable therewith,
A method for producing a copolymer latex, comprising adding a part of a chain transfer agent after completion of addition of a monomer.