JP2841669B2 - Method for producing copolymer latex - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention is to produce a copolymer latex which is excellent in properties such as adhesive strength, blister resistance, rigidity and the like when used in an adhesive or the like, and has a low odor. About the method.

[Prior art] A copolymer latex obtained by emulsion polymerization of a monomer comprising a conjugated diene monomer, an ethylenically unsaturated monomer, an ethylenically unsaturated carboxylic acid, etc., has excellent adhesiveness. Widely used as various adhesives.

In the production of these copolymer latexes, mercaptan compounds and disulfide compounds are effective as polymerization chain transfer and are widely used.

However, mercaptan compounds and disulfide compounds generally have an unpleasant odor, and this odor may be a problem not only during polymerization but also during product processing,
Reduction of this odor has been desired.

For this reason, for example, JP-A-53-121890 proposes the use of a non-sulfur type chain transfer agent having a low odor. However, these chain transfer agents are expensive and
There was a problem in practicality.

[Problems to be Solved by the Invention] The present invention relates to a method for producing a copolymer latex having excellent properties such as adhesive strength, blister resistance and rigidity when used in an adhesive or the like, and having substantially no odor. It is intended to provide.

[Means for Solving the Problems] As a result of intensive studies, the present inventors have found that the above object can be achieved by using a copolymer latex which is obtained by emulsion polymerization in the presence of rosin or a derivative thereof. The present inventors have found and completed the present invention based on this finding.

That is, the present invention relates to: (a) 10 to 80% by weight of a conjugated diene-based monomer (b) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer (c) Other copolymerizable vinyl-based monomers At this time, when 100 parts by weight of a monomer consisting of 10 to 89.5% by weight is emulsion-polymerized, (d) 0.1 to 10 parts by weight of a polymerization chain transfer agent (e) non-saponifiable rosin or its derivative 0.1 to 20 parts by weight The present invention provides a method for producing a copolymer latex, wherein emulsion polymerization is carried out at a pH of 7.5 or less in the presence of:

 Hereinafter, the present invention will be described in detail.

(A) Conjugated diene monomer Specific examples of the conjugated diene monomer include butadiene,
Examples thereof include isoprene, 2-chloro-1,3-butadiene, and 2-methyl-1,3-butadiene. These can be used alone or in combination of two or more. Of these, butadiene is particularly preferred.

The conjugated diene-based monomer is used for imparting appropriate elasticity and film hardness to the obtained copolymer. The amount of the conjugated diene-based monomer is 10 to 80% by weight based on all monomers, preferably 20 ~
It is selected from the range of 70% by weight. If the amount is less than 10% by weight, sufficient adhesive strength cannot be obtained, while if it exceeds 80% by weight, water resistance and adhesive strength are undesirably reduced.

(B) Ethylenically unsaturated carboxylic acid monomer Specific examples of the ethylenically unsaturated carboxylic acid monomer include monocarboxylic acids such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid. And half-esters such as methyl maleate, methyl itaconate, and β-methacryloxyethyl acid hexahydrophthalate. Also, anhydrides of dicarboxylic acids can be used. These can be used alone or in combination of two or more.

The amount of the ethylenically unsaturated carboxylic acid monomer to be used is selected from the range of 0.5 to 10% by weight, preferably 1 to 7% by weight, based on all monomers. If the amount used is less than 0.5% by weight, the mechanical strength of the copolymer latex will decrease in addition to the adhesive strength, while if it exceeds 10% by weight, the viscosity of the copolymer latex will increase and handling will be difficult. It becomes difficult and the operability decreases, which is not preferable.

(C) Other copolymerizable vinyl monomers Specific examples of other copolymerizable vinyl monomers include:
Styrene, α-methylstyrene, vinyltoluene, p-
Aromatic vinyl compounds such as methylstyrene, methyl (meth) acrylate, ethyl (meth) acrylate, (meth)
Alkyl or methacrylic acid alkyl ester compounds such as butyl acrylate, 2-hydroxyethyl (meth) acrylate, glycidyl (meth) acrylate, acrylamide, methacrylamide, N, N-dimethylacrylamide, N-methylolacrylamide, etc. Acrylamide or methacrylamide compounds of ethylenically unsaturated carboxylic acids, carboxylic acid vinyl esters such as vinyl acetate, vinyl cyanide compounds such as 2-cyanoethyl (meth) acrylate, acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, and dimethylamino Basic monomers such as ethyl (meth) acrylate, diethylaminoethyl (meth) acrylate, 2-vinylpyridine and 4-vinylpyridine can be exemplified. These can be used alone or in combination of two or more. Of these, styrene is particularly preferred as the aromatic vinyl compound, methyl methacrylate is preferred as the alkyl ester compound, acrylonitrile is preferred as the vinyl cyanide compound, and acrylic acid, itaconic acid is preferred as the unsaturated carboxylic acid. Used for

These monomers have an appropriate hardness in the obtained copolymer,
It is used to impart elasticity and water resistance, and its amount is selected from the range of 10 to 89.5% by weight, preferably 20 to 79.5% by weight. If the amount is less than 10% by weight, the water resistance is poor, while if it exceeds 89.5% by weight, the copolymer becomes too hard, and the adhesive strength is undesirably reduced.

(D) Polymerization chain transfer agent Specific examples of the polymerization chain transfer agent used in the polymerization of the monomers (a) to (c) include, for example, octyl mercaptan, n-dodecyl mercaptan, t-dodecyl mercaptan, n- Mercaptans such as hexadecyl mercaptan, n-tetradecyl mercaptan, t-tetradecyl mercaptan; xanthogen disulfides such as dimethyl xanthogen disulfide, diethyl xanthogen disulfide, diisopropyl xanthogen disulfide; tetramethylthiuram disulfide, tetraethylthiuram disulfide, tetrabutyl thiol Thiuram disulfides; halogenated hydrocarbons such as carbon tetrachloride and ethylene bromide; hydrocarbons such as pentaphenylethane; and acrolein , Methacrolein, allyl alcohol, 2-ethylhexylthioglycholate, terpinolene, α-terpinene, γ-terpinene, dipentene, α-methylstyrene dimer (2-4-diphenyl-4-methyl-1-methyl)
Preferably, the pentene is at least 50 parts by weight) and 9,
Unsaturated cyclic hydrocarbon compounds such as 10-dihydroanthracene, 1,4-dihydronaphthalene, indene, and 1,4-cyclohexanediene; and unsaturated heterocyclic compounds such as xanthene and 2,5-dihydrofuran.

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

Of these, mercaptans, xanthogen disulfides, thiuram disulfides, α-methylstyrene dimers, unsaturated cyclic hydrocarbon compounds, and unsaturated heterocyclic compounds can be preferably used.

The amount of the polymerization chain transfer agent used in the present invention is
0.1 to 10 parts by weight, preferably 0.2 to 7 parts per 100 parts by weight
Parts by weight. If the amount of the polymerization chain transfer agent is less than 0.1 part by weight, the blister resistance is inferior, while if it exceeds 10 parts by weight, a large amount of coagulated product is generated during the emulsion polymerization, and the properties of the copolymer latex are substantially reduced. It will be difficult.

(E) Rosin or its derivative Specific examples of rosin or its derivative which is the component (e) used in the polymerization of the monomers (a) to (c) include gum rosin, wood rosin, tall oil rosin, and heat-treated rosin. , Hydrogenated rosin, maleic acid modified rosin,
Examples thereof include fumaric acid-modified rosin, formalin-modified rosin, their esterified products with monohydric alcohol or polyhydric alcohol, and polymerized rosin.

The amount of rosin and its derivatives used is
0.1 to 20 parts by weight, preferably 0.1 to 15 parts by weight per 100 parts by weight
Parts by weight, particularly preferably 0.5 to 10 parts by weight, more preferably 0.5 to 7 parts by weight.

If the amount is less than 0.1 part by weight, the reduction in the amount of the polymerization chain transfer agent, which is the object of the present invention, cannot be achieved, the odor of the obtained copolymer latex cannot be substantially eliminated, and the Improvement cannot be achieved. On the other hand, if the amount exceeds 15 parts by weight, a large amount of coagulated product is generated during polymerization, which is not preferable.

In the present invention, by using the polymerization chain transfer agent and rosin or a derivative thereof in combination, the amount of the polymerization chain transfer agent used can be relatively reduced, and as a result, an unpleasant odor due to a mercaptan compound, a disulfide compound, or the like. Can be substantially eliminated, and the rigidity can be further improved. The rosin or derivative thereof used in the present invention is desirably in a non-saponifiable form, and is preferably compatible with the latex polymer during polymerization. Therefore, when the rosin or the derivative thereof is saponified, it is compatible with the latex polymer. Becomes worse, which is not preferable.

The method for producing a copolymer latex in the present invention can be produced by a conventionally known emulsion polymerization method except that the above-mentioned monomer and rosin or a derivative thereof are used. That is, emulsion polymerization is carried out by adding a monomer, rosin or a derivative thereof, a polymerization initiator, an emulsifier, a polymerization chain transfer agent and the like to an aqueous medium (usually water).

There is no particular limitation on the polymerization initiator used for the emulsion polymerization in the present invention, for example, cumene hydroperoxide, diisopropylbenzene hydroperoxide, hydroperoxides such as paramenthane pyridine peroxide, benzoyl peroxide, lauroyl peroxide Uses organic polymerization initiators such as peroxides and azo compounds such as azobisisobutyronitrile and inorganic polymerization initiators such as potassium persulfate, sodium persulfate and ammonium persulfate can do.

In the present invention, when the organic polymerization initiator is used alone, the obtained copolymer latex has poor mechanical stability, and a large amount of coagulated product is generated during polymerization. Or in combination with an organic polymerization initiator.

In addition, the said polymerization initiator can also be used as what is called a redox-type polymerization initiator combined with reducing agents, such as sodium bisulfite.

Among these polymerization initiators, persulfates such as potassium persulfate and ammonium persulfate, or a combination thereof with azobisisobutyronitrile or benzoyl peroxide, and a combination of these with a reducing agent are preferably used. Is done.

The amount of the polymerization initiator used in the present invention is 100
It is usually 0.1 to 5 parts by weight, preferably 0.5 to 5 parts by weight.
~ 2 parts by weight. When using an inorganic polymerization initiator and an organic polymerization initiator together, the ratio of the organic polymerization initiator is as follows:
It is preferably at most 70% by weight of the total polymerization initiator, more preferably at most 50% by weight. The ratio of organic polymerization initiator is 70
If the amount is more than 10% by weight, problems such as the case where the organic polymerization initiator is used alone are not preferred.

The emulsifier used for 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 salts of higher alcohols such as sodium lauryl sulfate, alkyl benzene sulfonates such as sodium dodecylbenzene sulfonate, and sulfonates of aliphatic carboxylic acid esters such as sodium dioctyl sulfosuccinate; polyethylene Nonionic surfactants such as an alkyl ester type, an alkyl phenyl ether type, and an alkyl ether type of glycol can be used. As the amphoteric surfactant, a carboxylate, a sulfate, a sulfonate, a phosphate,
Phosphoric acid ester salts and those having an amine salt or a quaternary ammonium salt as a cation moiety can be mentioned. Specifically, as salts of alkyl betaines, lauryl betaine, stearyl betaine, cocoamido propyl pyrbetaine, salts of 2-undecylhydroxyethyl imidazolium betaine, and as the amino acid type, lauryl-β-alanine, stearyl- β-alanine, lauryldi (aminoethyl) glycine, octyldi (aminoethyl) glycine, and dioctyldi (aminoethyl) glycine salts.

Among these emulsifiers, an alkylbenzene sulfonate is particularly preferably used. More specifically, sodium dodecylbenzenesulfonate and the like are particularly preferably used. The alkyl benzene sulfonate may be used in combination with other surfactants such as sulfates of higher alcohols.
It may be used in combination with an anionic surfactant such as a sulfonate of an aliphatic carboxylic acid ester or a nonionic surfactant such as an alkyl ester type, an alkyl ether type or an alkylphenyl ether type of polyethylene glycol.

The amount of the emulsifier used is usually 0.0
It is 5 to 2 parts by weight, preferably 0.05 to 1 part by weight. If the amount of the emulsifier exceeds 2 parts by weight, the water resistance is poor and the foaming of the paper coating composition becomes remarkable, causing a problem during coating. When the 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.

The emulsion polymerization method and its conditions in the present invention are not particularly limited, and can be carried out under conventionally known methods and conditions.

For example, the addition method of the polymerization chain transfer agent may be any of a batch addition method, a split addition method, a continuous addition method, or a combination thereof.

As for the method of adding the monomer, a batch addition method,
Any of a split addition method, a continuous addition method, or a combination thereof may be used. Among these methods, the split addition method or the continuous addition method is preferred from the viewpoints of reduction in the formation of coagulated material and removal of reaction heat. Further, 10 to 10 of the monomer containing the whole or a part of the ethylenically unsaturated carboxylic acid monomer
50% by weight is polymerized in the first stage, and the remaining 50
According to the second-stage polymerization method in which the emulsion polymerization is carried out by continuously adding 9090% by weight, the formation of coagulated material in the polymerization step can be further reduced, and the paper coating composition aimed at by the present invention is effectively used. Thus, the emulsion polymerization of the present invention is preferably carried out by this two-stage polymerization method.

The rosin or a derivative thereof used in the production method of the present invention may be dissolved in a monomer such as an aromatic vinyl monomer or an ethylenically unsaturated carboxylic acid ester, or may be dissolved in an organic solvent and added. The former method of dissolving in a monomer and adding it is preferable. In the case where a two-stage polymerization method is employed in the production method of the present invention, rosin or a derivative thereof may be added in one of the first and second stages, or in both stages. It may be added.

When rosin or its derivative is saponified, the water solubility increases, and the effect of the present invention is lost.
Is 7.5 or less, preferably 7 or less, and more preferably pH 5 or less.

Further, a so-called seed polymerization method (seeding polymerization method) in which the above-mentioned monomer is polymerized in the presence of the seed latex and the rosin or the derivative thereof of the present invention may be employed.

The monomer composition of the seed latex is preferably 0.1 to 10% by weight of the ethylenically unsaturated carboxylic acid monomer, 50 to 50% of the monomer component (a) and / or (b).
99.9% by weight, 0 to 40% by weight, preferably 0.1 to 40% by weight of the ethylenically unsaturated crosslinkable monomer. The amount of the seed latex to be used is preferably 0.05 to 20 parts by weight (solid content) based on 100 parts by weight of all monomers polymerized in the presence of the seed latex.

The ethylenically unsaturated crosslinkable monomer is preferably divinylbenzene, ethylene glycol dimethacrylate and trimethylolpropane trimethacrylate, more preferably divinylbenzene.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. In the examples, “%” and “parts” are based on weight.

Examples 1 to 6 and Comparative Examples 1 to 4 (Production of Copolymer Latex A to F, a to d) 150 parts of water were charged into a 100 pressure-resistant reaction vessel.
After charging the first stage components (monomer, polymerization chain transfer agent, polymerization initiator, emulsifier, rosin or its derivative (dissolved in styrene)) shown in
Polymerized for hours.

Next, polymerization was carried out by continuously adding the monomer of the second stage, the polymerization chain transfer agent, rosin or its derivative (dissolved in a part of styrene of the monomer) over 8 hours. In addition, the emulsifier of the second stage component was added all at once 5 hours after the start of the addition. Thereafter, in order to complete the polymerization, the reaction was further continued for 3 hours, and the polymerization was terminated at a polymerization conversion of 98%. In addition,
The pH during the polymerization was less than 2.5.

The resulting copolymer latex was adjusted to pH 7.5 using sodium hydroxide, and then steam was blown to remove unreacted monomers.Further, the solid content concentration was adjusted to 50% by heating under reduced pressure, The copolymer latexes A to F of the examples of the present invention and the copolymer latexes a to c of the comparative examples were obtained.

Further, except that 1.80 parts by weight of sodium hydroxide was added to the first stage and the pH at the time of polymerization was adjusted to 8.5 outside the range of the present invention, polymerization was carried out in the same manner as the above copolymer latexes A to F. An example copolymer latex d was obtained.

With respect to each of the obtained copolymer latexes A to F and ad, the gel content and the state of generation of odor were examined by the following methods.

Gel content The copolymer latex was adjusted to pH 8.0, coagulated with isopropanol, washed, and dried. Then, about 0.
A sample of 3 g was collected and immersed in 100 ml of toluene for 20 hours, and the toluene insoluble content was measured.
Was determined as the gel content.

Odor Copolymer latex was coated on a polester film with a coating rod at a coating amount of 10 g / m ² using a coating rod, and the odor when dried at 120 ° C. for 30 seconds was determined by odor. evaluated.

：: Almost no odor Δ: Slight odor X: Strong odor (Preparation of paper coating composition) Using the above copolymer latexes A to F, ad to paper coating according to the following formulation A composition (paint) was prepared.

Ingredients Clay 80 parts Calcium carbonate 20 parts Copolymer latex 10 parts Starch oxide 5 parts Sodium pyrophosphate 0.5 part Water The amount that total solid content becomes 60% The obtained paint was evaluated by the following test method. The results are shown in Table 2. The coated paper used in the test was obtained by applying a coating material to a base paper having a basis weight of 64 g / m ² using a coating blade at a coating amount of 20 g / m ² .

Dry Pick (Indicator of Adhesive Strength) The degree of picking when printed with an RI printing machine was judged with the naked eye, and evaluated by a five-step method. The higher the score, the better. The score was indicated by an average value of six measurements.

RI Wet Pick (Indicator of Water Resistance) The degree of picking when printing was performed by applying dampening water using a Molton roll with an RI printing machine was visually judged, and evaluated by a five-point method. The higher the score, the better. The score was indicated by an average value of six measurements.

Blister resistance After the double-sided printing coated paper was humidified (about 6%), it was thrown into a heating oil bath, and the lowest temperature at which blisters were generated was indicated.

Stiffness Measured with a Gurley stiffness meter. Larger values are better.

Examples 1 to 6 are examples using copolymer latexes A to F produced using rosin or a derivative thereof within the scope of the present invention, and Comparative Examples 1 to 3 do not use rosin or a derivative thereof. Comparative Example 4 is an example using the copolymer latex d produced under the condition that the pH of the polymerization system is excessively high.

Note that Comparative Examples 1, 2, 3, and 4 correspond to Examples 1, 3, 4, and 1 respectively in terms of monomer composition.

In Examples 1, 3, and 4, the gel content was lower than that of Comparative Examples 1, 2, and 3 even though the amount of the polymerization chain transfer agent was small in the same monomer composition. It can be seen that the efficiency of the transfer agent has increased. Also, Comparative Example 4 has a significantly higher gel content than Example 1, indicating that the efficiency of the polymerization chain transfer agent is inferior.

In addition, the odor of the obtained copolymer latex during drying of the coating film is considerably improved because the amount of the polymerization chain transfer agent used in the examples is relatively reduced as compared with the comparative example. .

Further, it can be seen that, in the coated paper properties, the Examples are generally superior to the Comparative Examples in terms of adhesive strength, water resistance, blister resistance, and rigidity.

[Effects of the Invention] According to the present invention, by using rosin or a derivative thereof during polymerization, it is possible to relatively reduce the amount of the polymerization chain transfer agent, and as a result, the amount of the polymerization chain transfer agent is reduced. Problems can be improved, for example, the odor of the obtained copolymer latex can be reduced, and further, the coating properties such as adhesive strength, water resistance and blister resistance, and rigidity can be improved. Useful as an adhesive.

The copolymer latex obtained by the present invention is, in particular,
It can be suitably used as a binder for a paper coating composition of coated paper and coated paperboard, and further can be used for various adhesive applications such as carpet backing agents, paints, industrial and household adhesives.

Continuation of the front page (72) Inventor Shozo Nishida 2-11-24 Tsukiji, Chuo-ku, Tokyo Japan Synthetic Rubber Co., Ltd. (56) References JP-A-61-57613 (JP, A) (58) Fields investigated (Int.Cl. ⁶ , DB name) C08F 2/00-2/60

Claims (2)

(57) [Claims] (1) 10 to 80% by weight of a conjugated diene monomer, (b) 0.5 to 10% by weight of an ethylenically unsaturated carboxylic acid monomer, and (c) another copolymerizable vinyl monomer. (E) 0.1 to 10 parts by weight of a polymerization chain transfer agent, and (e) 0.1 to 20 parts by weight of a non-saponifiable rosin or a derivative thereof. A method for producing a copolymer latex, wherein emulsion polymerization is carried out at a pH of 7.5 or less in the presence of: 2. The method for producing a copolymer latex according to claim 1, wherein the rosin or the derivative thereof as the component (e) is dissolved in a monomer or an organic solvent and added to the system.