KR840001690B1 - Process for producing copolymer latex - Google Patents

Abstract

Latexes useful as binders for paper coating are prepd. by emulsion polymerizing 1-30 wt. parts(1) α,β-ethylenic unsatd. carboxylic acid monomer 10-50, α,β-ethylenic unsatd. carboxylic acid hydroxyalkyl ester monomer 6-15 and one or more monomer(s) mixt. 1-30wt.% selected from conjugated diene monomer, α,β-ethylenic unsatd. carboxylic acid alkyl ester monomer, and arom. vinyl monomer followed by addn. polymerizing 70-99 wt. part(2) conjugated diene monomer 20-60, arom. vinyl monomer 20-70, and α,β-ethylenic unsatd. carboxylic acid alkyl ester monomer 3-40wt.%.

Description

Method for producing copolymer latex

The present invention relates to a method for producing copolymer latex having good stability.

More specifically, (a) 10 to 50% by weight of the α, β-ethylenically unsaturated carboxylic acid monomer, 6 to 15% by weight of the α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer and the remainder of the conjugated diene monomer 1 to 30 parts by weight of a monomer mixture comprising one, two or more monomers selected from α, β-ethylenically unsaturated carboxylic acid alkyl ester monomers and aromatic vinyl monomers, and (b) in the presence of the obtained copolymer latex. 70 to 99 parts by weight of a monomer consisting of 20 to 60% by weight of a conjugated diene monomer, 20 to 70% by weight of an aromatic vinyl monomer and 3 to 40% by weight of an α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer A method for producing a copolymer latex.

In general, copolymer latex is used alone or mixed with various pigments, adhesives and the like for paper coating or the back sizing of the car pit.

The copolymer latex used in these applications should have sufficient stability to mechanical shear during polymerization or coating process, chemical stability when mixed with various pigments, and sufficient adhesive strength or water resistance as an adhesive. Was required.

Furthermore, in order to adapt to the paper-evolving technology and printing technology, which is progressing continuously, it is not only excellent in latex, that is, chemical and mechanical stability, but also excellent in adhesion, water resistance, blister resistance, and heat set roughening resistance of coated paper. Etc. High performance is required.

MEANS TO SOLVE THE PROBLEM The present inventors conducted the research in order to obtain the copolymer latex which can fully satisfy the electrical-required performance, and came to discover the method of obtaining the excellent copolymer latex.

That is, the present invention,

(b) 10 to 50% by weight of the α, β-ethylenically unsaturated carboxylic acid monomer, 6 to 15% by weight of the α, β-ethylenically unsaturated carboxylic acid hydroxy alkyl ester monomer and the rest of the conjugated diene monomer, α, β-ethylene 1-30 parts by weight of a monomer mixture comprising one or two or more monomers selected from the group of unsaturated unsaturated carboxylic acid alkyl ester monomers and aromatic vinyl monomers,

(b) monomers 70 to 20 composed of 20 to 60 wt% of conjugated diene monomer, 20 to 70 wt% of aromatic vinyl monomer and 3 to 40 wt% of α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer in the presence of the obtained copolymer latex It is to provide a method for producing a copolymer latex, characterized in that the addition polymerization of 99 parts by weight.

Examples of the α, β-ethylenically unsaturated carboxylic acid monomer in the monomer polymerized in the first step of the present invention include acrylic acid, methacrylic acid, maleic acid fumaric acid and itaconic acid. The said carboxylic acid monomer can use together 1 type (s) or 2 or more types.

The α, β-ethylenically unsaturated carboxylic acid monomer is used in 10 to 50% by weight, but less than 10% by weight, the adhesive strength is lowered, the mechanical stability of the latex is lowered, and when the 50% by weight, the viscosity of the latex is excessively high.

As the α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer, β-hydroxyacrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, Hydroxybutyl methacrylate, 3-chloro-2-hydroxybutyl methacrylate, di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2 -Hydroxyethyl) maleate, 2-hydroxyethylmethylfumarate, and the like, and one or two or more thereof can be used. In the first stage polymerization, 6 to 15% by weight of the α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer is used in the monomer used.

If it is less than 6 weight%, the stability of the final copolymer latex worsens, and if it exceeds 15 weight%, the water resistance of a coated paper will become bad.

Examples of the conjugated diene monomer include 1,3-butadiene, 2-methyl-1,3-butadiene, 2-chloro-1,3-butadiene, and the like. Examples of the aromatic vinyl monomers include styrene, α-methylstyrene, methylalphamethylstyrene, vinyltoluene, and the like.

As the α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer, methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, butyl acrylate, 2-ethylhexyl acrylate, glycidyl methacrylate, dimethyl Fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate and monoethyl fumarate.

In the first stage polymerization, in addition to the α, β-ethylenically unsaturated carboxylic acid monomer and α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer, conjugated diene monomer, aromatic vinyl monomer and α, β-ethylenically unsaturated carboxylic acid One or two or more selected from alkyl ester monomers are used.

The monomer used in the first step is 1 to 30 parts by weight of the shearing material used, and less than 1 part by weight of the copolymer latex of the present invention cannot be obtained.

Moreover, when it exceeds 30 weight part, the water resistance of the coated paper using the obtained copolymer latex will fall.

Among the monomers polymerized in the second step, 20 to 60% by weight of the conjugated diene-based monomer is used, but less than 20 parts by weight, the adhesion of the coated paper is lowered, and if it exceeds 60% by weight, the water resistance of the coated paper is lowered.

Aromatic vinyl monomer is used in 20 to 70% by weight, but less than 20% by weight, the adhesion and water resistance of the coated paper is lowered, and if it exceeds 70% by weight, the film formability of the copolymer is reduced, resulting in poor adhesion of the coated paper.

In addition, the alpha, beta -ethylenically unsaturated carboxylic acid alkyl ester monomer is used 3 to 40% by weight, but less than 3% by weight, the light resistance of the coated paper is poor.

Moreover, when it exceeds 40 weight%, the water resistance of a coated paper will become bad. In the second step, the amount of the monomer used is 70 to 99 parts by weight of the shearing monomer used, and outside of these ranges, a copolymer latex having high stability cannot be obtained.

In addition, these monomers are preferably added and polymerized after the polymerization of the first stage of the polymerization proceeds at least 85% (polymerization conversion rate), but the double polymerization conversion rate is 90% or more in terms of water resistance of the coated paper and adhesiveness as a binder. Should be the most desirable.

The copolymer latex of the present invention is polymerized by a batch, split, continuous addition polymerization method or the like in any of the first and second steps.

In addition, in polymerization, a well-known emulsifier, a polymerization initiator, a chain transfer agent, etc. are used.

As emulsifiers, anionic surfactants such as sulfuric acid esters of higher alcohols, alkylbenzene sulfonates and aliphatic sulfonates. Or 1 type, or 2 or more types of nonionic surfactants, such as the alkyl ester type of polyethyleneglycol, an alkylphenyl ether type, and an alkyl ether type, are used.

When considering the water resistance of the obtained copolymer latex, it is good to use at 2 weight part or less with respect to monomer amount. As an initiator, useful initiators, such as water-soluble initiators, such as potassium persulfate, ammonium persulfate, and sodium persulfate, or a redox system initiator, or benzoyl peroxide, are used. As the chain transfer agent, mercaptans, halogenated hydrocarbons and the like are used.

The following examples are given, but these examples do not limit the invention.

Example 1

In a pressure-resistant container, 100 parts of monomers used in the first stage emulsion polymerization shown in Table 1 were added, 5 parts of sodium dodecylbenzenesulfonate, 3 parts of potassium persulfate, 20 parts of carbon tetrachloride, 1 part of tertiary dodecyl mercaptan, and sodium bicarbonate 3 parts of cerium and 400 parts of water were added, and it stirred and heated at 65 degreeC, mixing and stirring, and superposed | polymerized.

Next, 0.5 parts of sodium dodecylbenzenesulfonate, 0.5 parts of potassium sulfate, 2 parts of carbon tetrachloride, 0.1 parts of tertiary dodecyl mercaptan, and 0.3 parts of sodium bicarbonate And 80 parts of water were mixed and stirred, and this was continuously added to the pressure-resistant container, and it superposed | polymerized at 65 degreeC.

All the polymerization conversion rates were 99% or more. Unreacted monomer was removed by stripping and passed through a mesh of 200 mesh to obtain copolymer latex A ~ F. The viscosity and mechanical stability of the copolymer latex were measured by the following method.

Viscosity (cps):

It measured by BL-type viscometer (60 rpm, 25 degreeC).

Mechanical Stability (g):

200g of synthetic copolymer latex is obtained by measuring the amount of residue remaining in 100 mesh after 30 minutes in a Hamilton Pitch Mixer.

TABLE 1

Example 2

100 parts of monomers used in the emulsion polymerization of the first step of Table 2 were placed in a pressure-resistant container, and 5 parts of sodium dodecylbenzenesulfonate, 0.5 parts of potassium persulfate, 4 parts of carbon tetrachloride, 0.2 parts of tertiary dodecyl mercaptan, and bicarbonate 400 parts of sodium 5 parts of water was added and stirred, and the mixture was heated to 65 ° C and polymerized.

Next, 0.5 parts of sodium dodecylbenzenesulfonate, 100 parts of potassium persulfate, 4 parts of carbon tetrachloride, 0.2 parts of tertiary dodecyl mercaptan, and 0.5 parts of sodium bicarbonate were used in 100 parts of the monomers used in the second step emulsion polymerization of Table 2. 80 parts of water was mixed and stirred, and the mixture was continuously added to a pressure-resistant container heated to 70 ° C to polymerize. All the polymerization conversion rates were 99% or more.

Unreacted monomer was stripped and then passed through a mesh of 200 mesh to obtain copolymer latex G-K.

TABLE 2

Example 3

In a pressure-resistant container, 100 parts of monomers used in the emulsion polymerization of the first step shown in Table-3 were added, and 7.5 parts of sodium lauryl sulfate, 5 parts of potassium persulfate, 10 parts of carbon tetrachloride, and 0.4 parts of tertiary dodecyl mercaptan, 4.0 parts of sodium bicarbonate were added and stirred for 400 parts of water, and it heated up at 70 degreeC and superposed | polymerized.

Next, 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 80 parts of water After stirring and mixing, the mixture was continuously added into an internal pressure vessel and polymerized at 70 占 폚.

All the polymerization conversion rates were 99% or more.

The unreacted monomer was removed by spripping and then passed through a 200 mesh gold mesh to obtain copolymer latex L ~ Q.

TABLE 3

Example 4 (Comparative Example)

In the same polymerization method as in Example 3, polymerization and treatment were carried out using the monomer compositions shown in Table 4 to obtain copolymer latexes R-W.

TABLE 4

100 parts of monomers used in the first stage emulsion polymerization of Table 5 were put in a pressure-resistant container, and 7.0 parts of sodium lauryl sulfate, 5 parts of potassium persulfate, 10 parts of carbon tetrachloride, 1.0 part of tertiary dodecyl mercaptan, and 1.0 part of sodium bicarbonate 400 parts of water was added and mixed, and it superposed | polymerized at 65 degreeC. (Except Comparative Example Z) Next, 0.5 parts of sodium lauryl sulfate, 3 parts of potassium persulfate, 5 parts of carbon tetrachloride, and tertiary dodecyl mercaptan 0.2 in 100 parts of the monomer used in the second stage emulsion polymerization of Table 5 Part was added, 0.5 part of sodium bicarbonate and 80 parts of water were mixed and stirred, and the mixture was continuously added into a pressure resistant container and polymerized at 65 ° C.

Comparative Example Z was mixed with 100 parts of monomer composition, 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, 1.0 part of sodium bicarbonate, and 100 parts of water, and the polymerization temperature was 65 ° C. Polymerized.

All the polymerization conversion rates were 99% or more.

Unreacted monomer was stripped off and passed through a 200 mesh gold mesh to obtain copolymer latex X-Z.

TABLE 5

Example 6

Using the copolymer latex obtained in Examples 1-5, the coating liquid was created according to the combination shown next.

Composition of coating solution

Kaolin clay 70 parts (solid)

30 parts of calcium carbonate (solid content)

Denatured starch, 8 parts (solid)

12 parts of emulsion copolymer latex (solid content)

(62% total solids)

Using the obtained coating liquid, the fine base paper for coated paper was coated on one side and both sides using a Pured Coater, and dried. (The amount of coating is 10g / m2 on one side) Humidification is performed under conditions of 65% relative humidity and 20 ° C for one day and night, followed by super calender treatment under conditions of linear pressure of 80Kg / cm, temperature 60 ° C, speed of 5m / min and 2nip. I made it.

The performance of the obtained coated paper is described in Tables 6-10. The performance of coating liquid was taken as the following test method.

○ Roll Stability:

The coating solution is kneaded between rubber rolls using a perdaster vilister and subjected to mechanical shear to measure the time (minutes) until a coagulation occurs on the rubber rolls.

Longer time is preferred.

The performance of the coated paper was measured by the following test method.

○ RI dry peak:

The degree of picking at the time of printing by RI printing machine was visually judged, and evaluated by the 5-step method of the 1st grade (the best thing) to the 5th grade (the worst thing).

Six average values are displayed.

RI Wet Peak:

The degree of picking at the time of printing using a dampened product on the RI printing machine was visually determined and evaluated by a five-step method of first-class (best) to fifth-class (best).

Six average values are displayed.

○ Blister Resistance:

Humidification (approx. 6%) of double-sided printing coated paper is added to a heated oil bath and the lowest temperature when blister occurs.

TABLE 6

TABLE 7

TABLE 8

TABLE 9

TABLE 10

Example 7

Using the copolymer latex obtained by Example 1, the coating liquid was created for the mixing | blending shown next.

Composition of coating solution

Kaolin clay 70 parts (solid)

90 parts of heavy calcium carbonate (solid content)

0.2 part dispersant (solid content)

Denatured starch, 7 parts (solid)

12 parts of copolymer latex (solid content)

The coating solution was adjusted so that the solid content was 60%, and the coating solution was coated on the one side and both sides using a # 7 wire rod on a heavy paper (15% mechanical pump mixing rate).

After drying, it was treated with a super calendar.

The results of various physical properties of the obtained coated paper are shown in Table 11.

TABLE 11

○ Hit set roughening resistance:

The double-sided coated test side is printed on both sides using an RI printing tester.

His test side is placed in 200-250 ℃ silicon for 5 seconds, and the state of the subsequent hit set roughing is visually judged and evaluated by the 5-step method of 1st grade (best place) to 5th grade (best place). It was.

Claims (1)

10 to 50% by weight of the α, β-ethylenically unsaturated carboxylic acid monomer, 6 to 15% by weight of the α, β-ethylenically unsaturated carboxylic acid hydroxyalkyl ester monomer and the rest of the conjugated diene monomer, α, β-ethylenically unsaturated carbon Emulsifying and polymerizing 1 to 30 parts by weight of a monomer mixture composed of one or two or more monomers selected from main acid alkyl ester monomers and aromatic vinyl monomers; 70 to 99 parts by weight of a monomer composed of 20 to 60% by weight of a conjugated diene monomer, 20 to 70% by weight of an aromatic vinyl monomer and 3 to 40% by weight of an α, β-ethylenically unsaturated carboxylic acid alkyl ester monomer in the presence of the obtained copolymer latex. A method for producing a copolymer latex, characterized in that the addition polymerization.