JPH03166201A - Production of copolymer latex - Google Patents

Abstract

PURPOSE:To obtain the subject latex capable of providing a paper-coating composition excellent in bond strength and blister resistance by carrying out emulsion polymerization of a monomer mixture composed of a conjugated diene-based compound, an ethylenic unsaturated compound, etc., in the presence of a specified unsaturated cyclic compound. CONSTITUTION:A monomer mixture containing (A) 10-80wt.% conjugated diene- based compound (preferably butadiene), (B) 10-89.5wt.% ethylene-based unsaturated compound (preferably styrene, etc.) and (C) 0.5-10wt.% ethylenic unsaturated carboxylic acid (preferably maleic acid, etc.) is subjected to emulsion polymerization in the presence of (D) an unsaturated heterocyclic compound (preferably 4H-chromene) having a C-C double bond in the heterocycle and an H atom- bonded C atom adjacent to the C-C double bond and simultaneously constituting the heterocycle, thus obtaining the objective latex.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is applicable to paper coating compositions and carpet packings that generate less fine coagulum during polymerization and have excellent mechanical stability, adhesive strength, and blister resistance. This invention relates to a method for producing copolymer latex useful for materials, etc.

[Prior Art] Copolymer latex obtained by emulsion polymerization of monomers consisting of conjugated diene compounds, ethylenically unsaturated compounds, etc. can be used alone or in combination with casein, starch, protein, cellulose, polyvinyl alcohol, etc. It is well known that it can be used as a paper coating binder together with natural or synthetic binders.

Coated paper obtained by coating a paper coating composition containing this copolymer latex as a paper coating binder has good adhesive strength, water resistance, gloss, etc., and is used for a variety of purposes. There is.

In recent years, there has been a significant demand for printed matter using coated paper, and this has led to an increasingly strong trend toward faster printing and diversification of printing methods. For this reason, it is necessary to improve various physical properties of coated paper and, in turn, binders for paper coating, more than ever before, in particular, to improve gloss, print strength, water resistance, and blister resistance, all or several of them at the same time. It has become required. In particular, there is an increasing demand for improved adhesive strength and blister resistance for coated paper for rotary offset printing.

In order to meet these demands, various improvements have been made in the production of copolymer latexes used as binders for paper coatings. For example, JP-A-57-153012 and JP-A-61-63794 disclose that adhesive strength or blister resistance can be improved by modifying the method of adding a polymer chain transfer agent. Others: JP-A-50-107030, JP-A No. 55-906
Publication No. 97, Publication No. 60-38415, Publication No. 61-20
Patent No. 7694 and the like also disclose improved paper coating compositions and methods for producing the same.

[Problems to be Solved by the Invention] However, paper coating compositions using these conventional copolymer latexes still lack sufficient adhesive strength, blister resistance, and mechanical stability, and do not meet the above requirements. The reality is that we have not yet been able to adequately respond to this.

Further, if fine coagulates are generated during polymerization of the copolymer latex, it is technically difficult to remove the fine coagulates and cannot be easily removed. These fine coagulums pose a major problem because they significantly reduce the quality of coated paper.

Our objective is to solve these conventional problems and provide a method for producing a copolymer latex useful for paper coating compositions, carpet packing agents, etc., which has further improved adhesive strength and blister resistance. The purpose is to

[Means for Solving the Problems] That is, the present invention provides (a) a conjugated diene compound with 10 to
80% by weight, (b) 10 to 8 ethylenically unsaturated compounds
9.5% by weight, and (c) a monomer containing 0.5 to 10% by weight of ethylenically unsaturated carboxylic acid (hereinafter "monomer")
) is (d) an unsaturated heterocyclic compound having a carbon-carbon double bond in the heterocycle, wherein the unsaturated heterocyclic compound is adjacent to the carbon-carbon double bond and forms a heterocycle. At least one saturated carbon atom consisting of
A compound characterized in that it undergoes emulsion polymerization in the presence of a compound (hereinafter referred to as a "specific unsaturated cyclic compound") having a saturated carbon atom (hereinafter referred to as a "specific unsaturated cyclic compound") and in which the saturated carbon atom has at least one hydrogen atom. A method for producing polymer latex is provided.

The present invention will be explained in detail below.

Specific examples of the conjugated diene compound as component (a) used in the production of the copolymer latex of the present invention include butadiene, isoprene, 2-chloro-1,3-butadiene,
Examples include 2-methyl-1,3-butadiene. These can be used alone or in combination of two or more. Among these, butadiene is particularly preferred.

Component (a) is used to impart appropriate elasticity and film hardness to the resulting copolymer, and the amount used is 10 to 80% by weight, preferably 15 to 70% by weight of the monomers. %,
Particularly preferably, the amount is selected from the range of 20 to 60% by weight.

If the amount used is less than 10% by weight, sufficient adhesive strength cannot be obtained when the resulting copolymer latex is used, for example, in a paper-coated assembly, while if it exceeds 80% by weight, water resistance Also, the adhesive strength decreases, which is undesirable.

Specific examples of the ethylenically unsaturated compound as component (b) include aromatic vinyl compounds such as styrene, α-methylstyrene, vinyltoluene, and p-methylstyrene, methyl (meth)acrylate, and (meth)acrylic acid. ethyl,(
(meth)butyl acrylate, 2-hydroxyethyl (meth)acrylate, 2-hydroxylethyl (meth)acrylate, glycidyl (meth)acrylate, etc.
Acrylic acid alkyl esters, acrylamide, methacrylamide, (meth)acrylamide-based compounds such as N,N-dimethyl (meth)acrylamide and N-methylol (meth)acrylamide, carboxylic acid vinyl esters such as vinyl acetate, acrylonitrile, methacrylamide, etc. Examples include vinyl cyanide compounds such as nitrile and α-chloroacrylic nitrile. These can be used alone or in combination of two or more. Among these, styrene is particularly preferably used as the aromatic vinyl compound, methyl methacrylate as the alkyl ester compound, and acrylonitrile as the vinyl cyanide compound.

Component (b) is used to impart appropriate hardness, elasticity, and water resistance to the resulting copolymer, and the amount used is 10 to 89.5% by weight, preferably 20 to 89.5% by weight of the monomer. 89
．． 5% by weight, particularly preferably from 30 to 79.5% by weight. If the amount used is less than 10% by weight, the water resistance will be poor, while if it exceeds 89.5% by weight, the resulting copolymer latex will become too hard and, for example, when used in a paper coating composition, the adhesive strength will decrease. I don't like it.

Specific examples of the ethylenically unsaturated carboxylic acid compound as component (c) include monocarboxylic acids such as acrylic acid, methacrylic acid, and crotonic acid, dicarboxylic acids such as maleic acid, fumaric acid, and itaconic acid, and methyl maleate. , methyl itaconate, and half esters such as β-methacryloxyethyl acid hexahydride phthalate. Furthermore, anhydrides of the dicarboxylic acids listed above can also be used. These persimmons can be used alone or in combination of two or more persimmons.

Component (c) preferably includes at least one selected from dicarboxylic acids, monoesters thereof, and dicarboxylic anhydrides, and it is particularly preferred to use dicarboxylic acids. The weight ratio (α)/(β) of at least one fin (α) selected from dicarboxylic acid, dicarboxylic acid monoesters, and dicarboxylic acid anhydride to monocarboxylic acid (β) is usually 5 to 100. /9 5
-O, more preferably 10-95/90-5.

When used within this ratio range, the resulting paper coating composition using the copolymer latex will have excellent adhesive strength and mechanical stability.

The amount of component (c) used is 0.5 to 10% of the total monomers.
, preferably from 1 to 7% by weight. If the amount used is less than 0.5% by weight, the adhesive strength and mechanical stability of the copolymer latex will decrease, while if it exceeds 10% by weight, the viscosity of the copolymer latex will increase, making it difficult to handle. ) becomes difficult and the operability deteriorates, which is undesirable.

The copolymer latex in the present invention is obtained by emulsion polymerization of the above monomers in an aqueous medium, but the feature of the present invention is that this emulsion polymerization is carried out in the presence of a specific unsaturated cyclic compound. be.

This particular unsaturated cyclic compound is used as a polymerization chain transfer agent in the present invention.

The specific unsaturated cyclic compound of the present invention usually has 4 to 4 carbon atoms.
20, such as 2,5-dihydrofuran, α-bilane, γ-pyran, 3,6-dihydro-2H-pyran, 2
Examples include H-chromene, 4H-chromene, xanthene, phthalane, and 3H indole.

Among these specific unsaturated cyclic compounds, those in which one specific carbon atom is directly connected to two carbon-carbon double bonds are particularly preferable, such as 4H-chromene, xanthene, etc. can.

Note that the specific unsaturated cyclic compounds mentioned in ]2 may be substituted with an alkyl group having 1 to 10 carbon atoms, preferably 1 to 4 carbon atoms, such as a methyl group, an ethyl group, a butyl group, etc.

The above specific unsaturated cyclic compounds may be used singly or in combination of two or more.

In the present invention, compounds other than the above-mentioned specific unsaturated cyclic compounds can be used as the polymerization chain transfer agent.

As other polymerization chain transfer agents that can be used in combination with the above-mentioned specific unsaturated cyclic compound, known polymerization chain transfer agents used in general emulsion polymerization can be used.

Specifically, for example, octyl metal captan, n-dodecyl metal butane, t-dodecyl metal captan, n
- Mercabutanes such as hexadecylmercabutane, n-tetradecylmercabutane, and t-tetradecylmercabutane; xanthogen disulfides such as dimethylxanthogen disulfide, diethylxanthogen disulfide, and diisopropylxanthogen disulfide; tetramethylthiuram disulfide, tetraethylthiuram disulfide , thiuram disulfides such as tetrabutylthiuram disulfide; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as bentaphenylethane; Hexylthioglycolate, terpinolene, α-terbinene, γ-terbinene, dibentene, α-methylstyrene dimer (2-
4-diphenyl-4-methyl-1-bentene (preferably 50% by weight or more), 1,4-dihydronaphthalene, 1,4,5,8-tetrahydronaphthalene, 9.1
0-dihydroanthracene, 1,2,3.4-tetrahydronaphthalene, 1,4-cyclohexadiene, 1,2
-butadiene, 1,4-hexadiene, and the like. These can be used alone or in combination of two or more.

Among these, mercabutanes, xanthogen disulfides, thiuram disulfide, carbon tetrachloride, and the like are preferably used.

A specific unsaturated cyclic compound and another polymerization chain transfer agent (J
l: When used, the ratio is usually 2 to 100 unsaturated cyclic compound/other polymer chain transfer agent, weight ratio).

If the proportion of this specific unsaturated cyclic compound is less than 2% by weight, it is impossible to obtain a copolymer latex with excellent adhesive strength and blister resistance, less generation of fine coagulation, and excellent mechanical stability. .

The amount of the polymerization chain transfer agent containing the specific unsaturated cyclic compound used is usually 0.3 to 10 parts by weight, preferably 0.3 to 10 parts by weight, per 100 parts by weight of one monomer. It is 5 to 7 parts by weight. The amount of this polymerization chain transfer agent used is 0. If it is less than 3 parts by weight, the desired effect of the present invention cannot be obtained, while if it exceeds 10 parts by weight, the adhesive strength will decrease, which is not preferable.

The amount of the specific unsaturated cyclic compound to be used is 0.000 parts per 100 parts by weight of the monomer. It is preferable to use it in a range of 1 to 5 parts by weight.

The copolymer latex in the present invention can be produced by a conventionally known emulsion polymerization method, except that the above-mentioned monomers and specific unsaturated cyclic compounds are used.

That is, it is obtained by adding monomers, a polymerization initiator, an emulsifier, a polymerization chain transfer agent containing a specific unsaturated cyclic compound, etc. to an aqueous medium (usually water) and carrying out emulsion polymerization.

There are no particular limitations on the polymerization initiator used in the emulsion polymerization in the present invention, such as cumene hydroperoxide, diisopropylbenzene hydroperoxide,
Hydroperoxides such as paramenthane hydroperoxide, peroxides such as penzoyl peroxide and lauroyl peroxide, and organic polymerization initiators such as azo compounds such as azobisisobutyronitrile, as well as potassium persulfate and peroxide. Inorganic polymerization initiators such as persulfates such as sodium sulfate and ammonium persulfate can be used.

In the present invention, when an organic polymerization initiator is used alone, the mechanical stability of the copolymer latex obtained is poor;
Furthermore, since a large amount of coagulated material is generated during polymerization, it is preferable to use an inorganic polymerization initiator alone or in combination with an organic polymerization initiator.

The above polymerization initiator can also be used as a so-called redox polymerization initiator in combination with a reducing agent such as sodium bisulfite.

Among these polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate, combinations thereof with azobisisobutyronitrile or penzoyl peroxide, and combinations thereof with reducing agents are preferably used. be done.

The amount of the polymerization initiator used in the present invention is usually 0.1 to 5 parts by weight, preferably 0.1 to 5 parts by weight, per 100 parts of monomer.
．． The amount is 5 to 2 parts by weight. When an inorganic polymerization initiator and an organic polymerization initiator are used together, the proportion of the organic polymerization initiator is preferably 70% by weight or less, more preferably 50% by weight or less of the total polymerization initiator. If the proportion of the organic polymerization initiator exceeds 70% by weight, problems similar to those caused when the organic polymerization initiator is used alone are undesirable.

The emulsifier used in the emulsion polymerization in the present invention is not particularly limited, and any of anionic, nonionic and amphoteric surfactants can be used. These can be used alone or in combination of two or more. For example, anionic surfactants such as sulfate ester salts of higher alcohols such as sodium lauryl sulfate, alkylbenzene sulfonates such as sodium dodecylbenzenesulfonate, sulfonates of aliphatic carboxylic acid esters such as sodium dioctyl sulfosuccinate, polyethylene Nonionic surfactants such as glycol alkyl ester type, alkyl phenyl ether type, and alkyl ether type can be used.

In addition, amphoteric surfactants include those having carboxylates, sulfate ester salts, sulfonates, phosphates, and phosphate ester salts as anionic moieties, and amine salts and quaternary ammonium salts as cationic moieties. can be mentioned. Specifically, alkylbentine salts include laurylbetaine, stearylbetaine, cocoamidopropylbetaine, and 2-undecylhydroxyethylimidazolium betaine salts, and amino acid types include laurylβ-alanine and stearylβ-alanine. , lauryl di(aminoethyl)glycine, oxytyldi(aminoethyl)glycine, and dioctyldi(aminoethyl)glycine.

Among these emulsifiers, alkylbenzene sulfonates are particularly preferably used. More specifically, sodium dodecylbenzenesulfonate and the like are particularly preferably used. More specifically, sodium dodecylbenzenesulfonate and the like are particularly preferably used. This alkylbenzene sulfonate can be used with other surfactants, such as anionic surfactants such as sulfate ester salts of higher alcohols, sulfonate salts of aliphatic carboxylic acid esters, or alkyl ester or alkyl ether types of polyethylene glycol. It may be used in combination with a nonionic surfactant such as an alkyl phenyl ether type surfactant.

The amount of emulsifier used is usually 0.00 parts per 100 parts by weight of monomer.
0.05 to 2 parts by weight, preferably 0.05 to 1 part by weight. If the amount of emulsifier used exceeds 2 parts by weight, water resistance will be poor and the paper coating composition will foam significantly, causing problems during coating.

In addition, when an alkylbenzene sulfonate is used in combination with another anionic or nonionic surfactant, the proportion of the alkylbenzene sulfonate used is preferably 50% by weight or more of the total emulsifier.

There are no particular limitations on the emulsion polymerization method and conditions in the present invention, and the emulsion polymerization can be carried out under conventionally known methods and conditions.

For example, regarding the addition method of a polymerization chain transfer agent containing a specific unsaturated cyclic compound, there are a batch addition method, a divided addition method,
Either a continuous addition method or a combination thereof may be used.

Furthermore, the method of adding the monomer may be any one of a batch addition method, a divided addition method, a continuous addition method, or a combination thereof. Among these methods, the divided addition method or the continuous addition method is preferable from the viewpoint of reducing the formation of coagulum and removing the heat of reaction.

Furthermore, 10 to 50% by weight of the monomer containing the entire amount or 1 part of the ethylenically unsaturated carboxylic acid monomer is polymerized in the first stage, and the remaining 50 to 90% by weight of the monomer is polymerized in the second stage. According to the two-stage polymerization method in which continuous addition is carried out and emulsion polymerization is carried out, the formation of coagulum in the polymerization process can be further reduced, and the paper coating composition targeted by the present invention can be effectively obtained. Therefore, it is preferable to carry out the emulsion polymerization of the present invention by this two-stage polymerization method. In this method, the polymer chain transfer agent may be added to either the first stage or the second stage, or may be added to both.

When a polymer chain transfer agent is used in the second stage, it is preferable to add it sequentially.

The gel content of the obtained copolymer latex is preferably 5% or more, more preferably 10 to 9%. If the gel content is less than 5%, it is undesirable because adhesive strength and mechanical stability are greatly reduced, and furthermore, problems such as backing and grol staining occur as the tackiness of the Larax film increases. In addition, when the gel content exceeds 98%,
This is not preferable because it tends to reduce the adhesion quality.

The copolymer latex obtained according to the present invention can be used in paper coating materials and carpet packing materials by blending it with inorganic pigments or organic pigments, preferably inorganic pigments alone or with other binders as necessary. The amount of the copolymer latex obtained according to the present invention, which can be used as ~20 parts by weight. Further, the amount of other binders added as necessary is usually 10 parts by weight or less, preferably 2 to 5 parts by weight, based on 100 parts by weight of the pigment, in terms of solid content.

As inorganic pigments, kaolin clay, talc, barium sulfate, titanium oxide (rutyl anatase), calcium carbonate, aluminum hydroxide, zinc oxide, satin white, etc. can be used, and as organic pigments, boristyrene latex etc. can be used. . These can be used alone or in combination of two or more.

Other binders include natural binders such as starch, oxidized starch, soybean protein, and casein, and synthetic latexes such as polyvinyl alcohol, polyvinyl acetate latex, and acrylic latex.

The paper coating composition using the copolymer latex obtained by the present invention further contains various commonly used auxiliary agents, such as dispersants (sodium birophosphate, sodium hexametaphosphate, etc.), antifoaming agents (polymer glycol, aliphatic ester, phosphate ester, silicone oil, etc.),
Leveling agents (funnel oil, dicyandiamide, urea, etc.), preservatives, water resistance agents (formalin, hexamine, melamine resin, urea resin, glyoxal, etc.), mold release agents (calcium stearate, paraffin emulsion, etc.)
, a fluorescent dye, and a color retention improver (carboxymethylcellulose, sodium alginate, etc.) may be added as necessary.

The paper coating composition using the copolymer latex obtained according to the present invention can be applied by a conventionally known method, for example, using an air knife coater, a blade-y-roll coater, an applicator, or the like.

[Examples] The present invention will now be described in more detail with reference to Examples. In addition, "%" and "r part" in the examples are based on weight.

Examples 1 to 7, Comparative Examples 1 to 5 (Manufacture of copolymer latex) In a pressure-resistant container of 1002, the monomers shown in Table 1, water, a polymer chain transfer agent containing a specific unsaturated cyclic compound, and an emulsifier. After charging the first stage of each of emulsifier and emulsifier, polymerization was carried out at a temperature of 70° C. for 2 hours in a nitrogen atmosphere. Next, the second stage components shown in Table 1 were continuously added over 8 hours to carry out polymerization. Thereafter, in order to complete the polymerization, the reaction was continued for an additional 3 hours to complete the polymerization.

In Example 1, the first stage polymerization was carried out for 6 hours and 2
The stage polymerization was carried out over a period of 2 hours.

After adjusting the pH of the obtained copolymer latex to 7.5 using sodium hydroxide, unreacted monomers were removed by blowing in water vapor, and a copolymer latex with a solid content concentration of 50% was obtained by heating and vacuum distillation. (A-G and I-H)
I got it.

The gel content of the copolymer latexes (A-G and I-H) was determined by the following method.

After adjusting the copolymer latex to pH 8.0, it was coagulated with isopropanol, washed, and then dried.゛Next,
Approximately 0.3 g of a sample was taken and immersed in 100 ml of toluene for 20 hours, and then the toluene insoluble matter was measured, and the ratio (%) to the sample was determined to be the gel content.

Furthermore, the amount of coagulated material generated during polymerization of the copolymer latexes (A-G and I-H) was measured by the following method.

Collect 1 kg of copolymer latex as a sample, filter it through a 400-mesh wire mesh, measure the amount of coagulated material remaining on the wire mesh, calculate the proportion to the sample (in terms of solid content), and perform the following three steps: evaluated.

○: Less than 0.05% (little) △: 0.05% to 0.1% (slightly more) X: Q, more than 1% (quite a lot) (Adjustment of paper coating composition) The above copolymer A paper coating composition (color) was prepared using latex (A-G and I-H) according to the following formulation.

Clay 80 parts Calcium carbonate 20 parts Copolymer latex 10 parts Oxidized starch 5 parts Sodium pyrophosphate 0.5 part Water Amount to give a total solid content of 60% The obtained color was evaluated by the following test method.

The coated paper used in the test weighed 64g of color.
/rrr atoms are coated with a coating blade f
It was obtained by coating with fi20 g/m'.

■ Rl Dry Pick: Indicator of Adhesive Strength The degree of picking when printed with an RI printing machine was visually judged and evaluated using a 5-step method. The higher the score, the better. The score was expressed as the average value of 6 measurements.

■ Blister resistance After the double-sided printed coated paper was conditioned to humidity (approximately 6%), it was thrown into a heated oil bath and the lowest temperature at which blistering occurred was determined.

■ Mechanical stability The color was prepared to a solid content concentration of 20% by weight, and was heated between rubber rolls at a pressure of 10kg at 100r using a gum-up tester.
pm, knead at 60°C, apply mechanical shearing, and measure the time (minutes) until coagulation occurs on the rubber roll.
Evaluation was made on the following three levels.

○: 20 minutes or more △: 10-20 minutes ×: 10 minutes or less The results are shown in Table-2.

Margins below [Effects of the Invention] According to the present invention, it is possible to produce a copolymer latex that generates very little fine coagulum during polymerization and has excellent adhesiveness, blister resistance, and mechanical stability.

A paper-coated assembly using the copolymer latex obtained by the present invention can be suitably used for producing coated paper, particularly coated paper for rotary offset printing.

Claims (1)

[Claims] (1) (a) 10 to 80% by weight of a conjugated diene compound, (b) 10 to 89.5% by weight of an ethylenically unsaturated compound
, and (c) a monomer containing 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid; (d) an unsaturated heterocyclic compound having a carbon-carbon double bond in the heterocycle; The unsaturated heterocyclic compound is
Emulsion polymerization is carried out in the presence of a compound having at least one saturated carbon atom constituting a heterocycle adjacent to a carbon-carbon double bond, and in which the saturated carbon atom has at least one hydrogen atom. A method for producing a copolymer latex.