JPS6019928B2 - Method for producing copolymer latex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for producing a copolymer latex with good stability.

For details, see 'a) Ethylenically unsaturated carboxylic acid monomer 10-5% by weight, monomer containing hydroxyalkyl group 6-15%
A monomer in which the weight percent and the remainder are one or more monomers selected from aliphatic conjugated diene monomers, ethylenically unsaturated carboxylic acid alkyl ester monomers, and alkenyl aromatic vinyl monomers. Parts by weight of thermocompounds 1 to 3 are emulsion polymerized, {b-in the presence of the obtained copolymer latex,
A monomer consisting of 20-6% by weight of an aliphatic conjugated diene monomer, 20-7% by weight of an alkenyl aromatic monomer, and 3-4% by weight of an unsaturated carboxylic acid alkyl ester monomer. This is a method for producing a copolymer latex, characterized in that 70 to 9 parts by weight of the copolymer latex is added and polymerized.

Generally, copolymer latexes are used alone or mixed with various pigments, adhesives, etc. for paper coatings, carpet backsizing, etc.

The English polymer latex used for these applications has sufficient stability against mechanical stress during polymerization or coating processes, and has sufficient chemical stability when mixed with various pigments, etc., and also has sufficient stability as an adhesive. Adhesive strength or water resistance is required to be sufficient.

Furthermore, in order to adapt to the advancing paper coating and printing technologies, it is necessary to use latex that has excellent chemical and mechanical stability, as well as coated paper's adhesion, water resistance, and resistance. High specular performance is required, including good blister resistance and heat set roughening resistance.

The present inventors conducted repeated research with the aim of obtaining a copolymer latex that satisfactorily satisfies the above-mentioned required performance, and as a result, they found a method for obtaining an excellent copolymer latex and arrived at the present invention. .

That is, the present invention consists of {a-10 to 5% by weight of an ethylene unsaturated carboxylic acid monomer, 6 to 15% by weight of a monomer containing a hydroxyalkyl group, and the remainder being an aliphatic conjugated diene monomer, ethylene. Monomer mixture 1 consisting of one or more monomers selected from unsaturated carboxylic acid alkyl ester monomers and alkenyl aromatic vinyl monomers
~3 parts by weight are emulsion polymerized, 'b} In the presence of the obtained copolymer latex, 20 to 6 parts by weight of aliphatic conjugated gene monomers are
70 to 9 parts by weight of a monomer consisting of 20 to 7 parts by weight of an alkenyl aromatic monomer and 3 to 4 parts by weight of an unsaturated carboxylic acid alkyl ester monomer are added and polymerized. This is a method for producing a copolymer latex characterized by the following.

Examples of the ethylenically unsaturated carboxylic acid monomers to be polymerized in the first step of the present invention include acrylic acid, methacrylic acid, fumaric acid, maleic acid, and itaconic acid.

The above carboxylic acid monomers can be used alone or in combination of two or more. The ethylenically unsaturated carboxylic acid monomer is used in an amount of 10 to 5% by weight, but if it is less than 1% by weight, the adhesive strength and mechanical stability of the latex will decrease, and if it exceeds 5% by weight, the latex will deteriorate. viscosity becomes too high.

Examples of the unsaturated monomer containing a hydroxyalkyl group include 8-hydroxyethyl acrylate, 8-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate,
Examples include 3-chloro-2-hydroxybutyl methacrylate, di(ethylene glycol) maleate, di(ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis(2-hydroxyethyl) maleate, and 2-hydroxyethylmethyl fumarate. →Used in one species or in two or more species.

In the monomers used in the first stage polymerization, the unsaturated monomer containing a hydroxyalkyl group is used in an amount of 6 to 15% by weight.

If it is less than 6% by weight, the stability of the final copolymer latex will be poor, and if it exceeds 15% by weight, the water resistance of the coated paper will be poor.

Aliphatic conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene and 2-chloro-
Examples include 1,3-butadiene.

Examples of the alkenyl aromatic monomer include styrene, alphamethylstyrene, methylalphamethylstyrene, and vinyltoluene. Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, and dimethyl maleate. , diethyl maleate, dimethyl itaconate, monomethyl fumarate, and monoethyl fumarate. Among the monomers used in the first stage polymerization, the remaining monomers excluding ethylenically unsaturated carboxylic acid monomers and monomers containing hydroxyalkyl groups include aliphatic conjugated diene monomers, alkenyl One or more selected from aromatic monomers and unsaturated carboxylic acid alkyl ester monomers are used.

The amount of the monomer used in the first step is 1 to 3 parts by weight, and if it is less than 1 part by weight, the copolymer latex of the present invention cannot be obtained.

If the amount exceeds 3 parts by weight, the water resistance of the coated paper using the obtained copolymer latex will decrease. Among the monomers that are then polymerized in the second stage, conjugated 5-gen monomers account for 20
It is used in an amount of ~6% by weight, but if it is less than 20 parts by weight, the adhesive strength of the coated paper will decrease, and if it exceeds 6% by weight, the water resistance of the coated paper will decrease.

The alkenyl aromatic monomer is used in an amount of 20 to 7% by weight, but if it is less than 2% by weight, the adhesive strength and water resistance of the coated paper will decrease, and if it exceeds 7% by weight, the copolymer film will be reduced. Formability is reduced and as a result the adhesion of the coated paper is reduced.

In addition, the unsaturated carboxylic acid alkyl ester monomer is 3 to 4
If the amount is less than 3% by weight, the light resistance of the coated paper will deteriorate.

If the amount exceeds 4% by weight, the water resistance of the coated paper will deteriorate.
The monomer used in the second stage is used in an amount of 70 to 9 parts by weight, but a highly stable English polymer latex cannot be obtained outside this range.

It is preferable that these monomers be added and polymerized after 85% or more of the monomers in the first stage have been polymerized (polymerization conversion rate); 90% or more is most preferable.

The copolymer latex of the present invention is polymerized in both the first stage and the second stage by a known batch, division, continuous addition polymerization method, or the like.

Further, during polymerization, known emulsifiers, polymerization initiators, chain transfer agents, etc. are used. Examples of emulsifiers include anionic surfactants such as sulfate esters of higher alcohols, alkylbenzene sulfonates, and aliphatic sulfonates, and nonionic surfactants such as alkyl ester, alkyl phenyl ether, and alkyl ether types of polyethylene glycol. One or more types of agents are used.

Considering the water resistance of the obtained copolymer latex,
It is preferable to use 2 parts by weight or less based on the monomer weight. As the initiator, water-soluble initiators such as potassium persulfate, ammonium persulfate, and sodium persulfate, redox-based initiators, or oil-soluble initiators such as penzoyl peroxide can be used.

As the chain transfer agent, mercaptans, halogenated hydrocarbons, etc. can be used.

Examples are shown below, but the present invention is not limited by the examples.

Example 1 In a pressure-resistant container, 10 monomers used in the first stage of emulsion polymerization shown in Table 1 were added, 5 parts of sodium dodecylbenzenesulfonate, 3 parts of potassium persulfate, and 2 moles of carbon tetrachloride. A mixture of 1 part of tertiary dodecyl mercaptan, 3 parts of sodium bicarbonate, and 400 parts of water was mixed with the monomers to be subjected to emulsion polymerization in the first stage, and the mixture was heated to 65 qo to perform polymerization. Ta.

Next, single star body 1 used in the second stage of emulsion polymerization in Table 1
0 parts, 0.5 parts of sodium dodecylbenzenesulfonate, 0.5 parts of potassium persulfate, 2 parts of carbon tetrachloride
1 part, 0.1 part of tertiary dodecyl mercabutane, 0.3 part of bicarbonate of soda, and 80 parts of water, mixed with the monomer to be subjected to emulsion polymerization in the second stage, and continuously placed in a pressure container. and polymerization was carried out at 65°C. The polymerization conversion rate was 99 in both cases.
% or more.

After removing unreacted single stars by stripping, the mixture was passed through a 200-mesh wire gauze to obtain copolymer latexes A to F. The viscosity and mechanical stability of the copolymer latex were measured by the following method.

Viscosity (cps): It was measured using a BL type viscometer (6pm.2yo).

Mechanical stability (g): Obtained by taking 20 pieces of synthetic copolymer latex and measuring the amount of grooves remaining on 100 mesh after applying it to a Hamilton Beach mixer for 30 minutes.

Table 1 Example 2 In a pressure-resistant container, 10 monomers used in the first stage emulsion polymerization shown in Table 2 were added, 5 parts of sodium dodecylbenzenesulfonate, 0.5 parts of potassium persulfate, and 4 parts of sodium dodecylbenzenesulfonate. carbon chloride 4
0.2 parts of tertiary dodecyl mercaptan, 5 parts of sodium bicarbonate, and 40 parts of water were mixed with the monomers to be subjected to emulsion polymerization in the first stage. I did it.

Next, single enrichment 1 used in the second stage of emulsion polymerization in Table 2
0 parts of sodium dodecylbenzenesulfonate, 0.6 parts of potassium persulfate, 4 parts of carbon tetrachloride, 0.2 parts of tertiary dodecyl mercaptan, and 0.5 parts of sodium bicarbonate. and 80 parts of water, mixed with the monomer to be subjected to emulsion polymerization in the second stage, and continuously added to a pressure vessel heated to 70 degrees for polymerization.

The polymerization conversion rate was 99% or more in all cases.

After removing unreacted monomers by stripping, the mixture was passed through a 200-mesh wire gauze to obtain copolymer latexes G to K. Table 2 Example 3 In a pressure-resistant container, 7.5 parts of sodium lauryl sulfate, 5 parts of potassium persulfate, and 10 parts of carbon tetrachloride were added to 10 liters of the monomers used in the first stage of emulsion polymerization shown in Table 3. 0.4 parts of tertiary dodecyl mercaptan, 4 parts of sodium bicarbonate. The mixture was mixed with water at a ratio of 40 parts, mixed with the monomer to be subjected to emulsion polymerization in the first stage, and polymerized by raising the temperature to 70 qo.

Next, monomer 1 used in the second stage emulsion polymerization in Table 3
0.5 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, 4 parts of carbon tetrachloride, 0.2 parts of tertiary dodecyl mercaptan, 0.5 parts of sodium bicarbonate, and 0.5 parts of sodium bicarbonate per 1 part of the anchor. The mixture was mixed with the monomers to be subjected to emulsion polymerization in the second stage, and continuously added to a pressure vessel to carry out polymerization at 7 p.m.

The polymerization conversion rate was 99% or more in all cases.

After removing unreacted monomers by stripping, the mixture was passed through a 200-mesh wire gauze to obtain copolymer latexes L to Q. Table 3 Example 4 (Bisame example) Copolymer latexes R to W were obtained by polymerization and treatment using the same polymerization method as in Example 3 and the monomer composition shown in Table 4.

Table 14 Example 5 In a pressure-resistant container, 7 parts of monomer 10 used in the first stage emulsion polymerization shown in Table 5 (excluding Comparative Example Z) were added. 5 parts of potassium persulfate, 1 part of carbon tetrachloride, 1.0 part of tertiary dodecyl mercaptan, 1 part of sodium bicarbonate. and 400 parts of water, 6y
Polymerization was carried out at o.

Next, monomer 1 used in the second stage of emulsion polymerization in Table 5
0.0 parts of sodium lauryl sulfate and 0.5 parts of potassium persulfate. $ parts, 5 parts of carbon tetrachloride, 0.2 parts of tertiary dodecyl mercaptan, 0.5 parts of sodium bicarbonate,
Water was mixed at a ratio of 8 parts to 8 parts, mixed with monomers to be polymerized in the second stage, and continuously added to a pressure vessel to carry out polymerization at 65 pm.

Comparative Example Z has a monomer composition of 10 parts, 1.5 parts of sodium lauryl sulfate, 0.3 parts of potassium persulfate, 4 parts of carbon tetrachloride, 0.3 parts of tertiary dodecyl mercaptan, and sodium bicarbonate. 1. Foundation part, 10 anchor parts of water, polymerization temperature 65oo
Polymerization was carried out using

The polymerization conversion rate was already 99% or more.

After removing unreacted monomers by stripping, the mixture was passed through a 200-mesh wire gauze to obtain English polymer latexes X to Z.

Table 5 Example 6 Using the copolymer latex obtained in Examples 1 to 5, a coating liquid was prepared according to the following formulation.

Composition of coating liquid Kaolin clay 7 base parts (solid content) Calcium carbonate 30 parts (〃) Modified starch 8 parts (〃) Emulsion copolymer latex 12 parts (〃) (Total solid content 62%)
Using the obtained coating liquid, high-quality base paper for coated paper was coated on one side and both sides using a blade coater, and then dried.

(The coating amount is 1 og/side) One day and night, the relative humidity is 65%, the temperature is 20 o○, and the humidity is controlled, and then the linear pressure is 80 k9/
A sample was prepared by super calendering under the conditions of temperature 60 oo, speed 5 m/min, and sand. The performance of the obtained coated paper is shown in Tables 6 to 10.

The performance of the coating liquid was tested using the following test method.

0-roll stability: The coating solution is kneaded between rubber rolls using a patter stability tester, a mechanical period is applied, and the time (minutes) until a coagulated substance appears on the rubber roll is measured.

The longer the time, the better. The performance of the coated paper was tested using the following test method.

oRI Dry Picking: The degree of picking when printed with an RI printing machine was visually judged and evaluated on a five-point scale from grade 1 (best) to grade 5 (worst).

The average value of 6 times is shown.

oRI Wet Pick: The degree of picking when printing with dampening water on an RI printing machine is judged visually and evaluated on a five-point scale from grade 1 (best) to grade 5 (worst). did.

The average value of 6 times is shown.

o Blister resistance: Double-sided printed coated paper is humidity-controlled (approximately 6%) and thrown into a heated oil bath, and the lowest temperature at which blisters occur is shown.

Table-6 Table-7 Table-8 Table-9 Table-10 Example 7 Using the copolymer latex obtained in Example 1, a coating liquid was prepared according to the following formulation.

Composition of coating liquid Kaolin clay 7 Foundation (solid content) Childhood calcium carbonate 3 No Miyako (〃) Dispersant
0.2 parts (〃) Modified starch 7 parts (〃) Copolymer latex 12 parts (〃)
The coating solution was adjusted to have a solid content of 60%, and the coating solution was applied to medium-quality base paper (mechanical pulp content: 15%) using a #7 wire rod in an amount equivalent to 1 umbrella on one and both sides. .

After drying, super calendering treatment was performed. Table 11 shows the results of various physical properties of the coated paper obtained. Table 11 o Resistance to heat set roughening: A test piece coated on both sides was printed on both sides using an RI printing tester, and the test piece was placed in silicon at 200 to 250°C for 5 seconds to evaluate the subsequent heat set roughening. The appearance was visually measured and evaluated on a five-point scale from grade 1 (best) to grade 5 (worst).

The average value of 6 times is shown.

Claims (1)

[Claims] 1 (a) Ethylenically unsaturated carboxylic acid monomer 10-
50% by weight, 6-15% by weight of unsaturated monomers containing hydroxyalkyl groups, and the remainder being aliphatic conjugated diene monomers, ethylenically unsaturated carboxylic acid alkyl ester monomers, and alkenyl aromatic vinyl monomers. Emulsion polymerization of 1 to 3 parts by weight of a monomer mixture consisting of one or more monomers selected from (b) aliphatic conjugated diene monomers in the presence of the obtained copolymer latex; Body 20-60% by weight
, a copolymer characterized by addition polymerization of 70 to 99 parts by weight of a monomer consisting of 20 to 70% by weight of an alkenyl aromatic monomer and 3 to 40% by weight of an unsaturated carboxylic acid alkyl ester monomer. Method for producing coalescing latex.