JPH03200802A - Production of copolymer latex and copolymer latex - Google Patents

Abstract

PURPOSE:To produce a copolymer latex which can give a coated paper for printing improved in the balance between pick strength and other performances and can give a (pressure-sensitive) adhesive of improved adhesive force by adding a specified water-insoluble solvent and a specified chain transfer agent to the reaction system in the emulsion-polymerization of a conjugated diene compound, an ethylenically unsaturated carboxylic acid and another copolymerizable monomer in an aqueous medium. CONSTITUTION:A copolymer latex is produced by emulsion-polymerizing at least three monomers of a conjugated diene compound, an ethylenically unsaturated carboxylic acid and another copolymerizable monomer in an aqueous medium in the presence of a nonpolymerizable water-insoluble solvent which is compatible with at least one of the above monomers and can swell or dissolve the formed copolymer and a chain transfer agent compatible with this solvent.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to improvements in a method for producing copolymer latex and to the copolymer latex obtained thereby. More specifically, the present invention provides a method for efficiently producing a high-performance copolymer latex suitable for use as a binder for paper coating, fiber binding for carpet back sizing, or adhesive. The present invention relates to the copolymer latex obtained by this method.

Conventional technology Conventionally, synthetic copolymer latex has been widely used, for example, as a binder for paper coating, a binder for carpet back sizing, a binder for binding fibers such as nonwoven fabrics and artificial leather, and an adhesive for various materials. There is. When a copolymer latex is used for such purposes, it is required that the copolymer latex has high adhesive strength and is excellent in water resistance, blistering resistance due to dry heating, and the like.

For example, coated paper uses kaolin clay, calcium carbonate, satin white,
Paints coated with pigments such as talc and titanium oxide, their copolymer latex as a binder, and water-retaining agents or starch as auxiliary binders, and paints whose main components are water-soluble polymers such as polyvinyl alcohol and carboxymethyl cellulose. As the copolymer latex, styrene-butadiene copolymer latex, so-called SB latex, which is obtained by emulsion polymerization of styrene and butadiene as main monomer components, has conventionally been widely used. It is used.

Incidentally, in recent years, the production of coated paper has increased significantly as demand for color-printed magazines, pamphlets, and advertisements has increased. In particular, with the trend toward higher speed printing in offset printing, the quality requirements for coated paper and pigment binders are becoming increasingly sophisticated. There is a strong need for improvement. Moreover, this pick strength performance has a negative correlation with other print properties, such as wet pick strength, blister resistance, halftone dot reproducibility, etc., so improvements that balance these physical properties to a high level are required. requested.

Since these properties of coated paper are particularly strongly dependent on the performance of the SB latex used as a pigment binder, various studies have been made on the performance of the SB latex.

For example, it has been confirmed that the proportion of the insoluble portion of the copolymer latex film in solvents such as benzene, toluene, and tetrahydrofuran is the controlling factor for pick strength and blister resistance, and various studies have been conducted from this point of view. Specifically, by adjusting the composition and gel fraction of the copolymer in the latex to a specific range,
It has been proposed to exhibit excellent performance (Japanese Patent Publication Nos. 59-3598, 17879-1980, and 4894-1989).

However, in general, the pick strength of coated paper is highest in SB latex with a gel fraction in the range of 75 to 95% by weight, while the blister resistance is better as the gel fraction is lower. It is recognized that
None of the above techniques is fully satisfactory in order to simultaneously improve both pick strength and blister resistance to a high level.

It is also known that a copolymer latex with excellent pick strength and blister resistance can be obtained by using a water-soluble organic solvent that is inert to the polymerization reaction in the polymerization process (Japanese Unexamined Patent Application Publication No. 1983-1998-1). 235593), in this case, since a large amount of the organic solvent is used, the resulting latex has the disadvantage of poor mechanical stability, and does not fully satisfy the above-mentioned required performance.

Furthermore, the optimal butadiene unit fraction for wet pick strength in offset printing is 34% by weight or less, which is different from the optimal butadiene unit fraction for pick strength, so it is necessary to simultaneously achieve high levels of both physical properties. It's difficult.

On the other hand, for gravure printing paper, good halftone dot reproducibility and supercalendar stain resistance during coated paper production are particularly important, and for example, good binders for gravure printing paper have been proposed (JP Since this product is designed to have a high butadiene unit fraction, the dot reproducibility is improved to a sufficient degree without impairing the super calendar stain resistance. has not yet been achieved.

On the other hand, carpet pack sizing adhesives are generally compositions of copolymer latex blended with fillers such as calcium carbonate or aluminum hydroxide and other additives such as thickeners. This adhesive composition is used in the manufacture of tufted carpets, needle bunch carpets, etc., mainly to prevent piles (cover yarns) from falling off and to bond with secondary base fabrics such as jute. Therefore, in this case, improving adhesive strength, which is an important physical property of carpet, is one of the biggest technical challenges in this industry, and therefore, improvements have been made from the aspect of blending copolymer latex and m-acid. However, the reality is that a satisfactory level has not been obtained so far.

On the other hand, adhesives have traditionally been manufactured by dissolving natural rubber, synthetic rubber, etc. in an organic solvent, coating it on a base material, and then evaporating the organic solvent. Due to the above problems, there is increasing momentum to use polymer aqueous dispersions (latex) using water as a dispersion medium, and aqueous dispersions of rubber-tackifying resin combinations are being developed (Japanese Patent Publication No. 57-28545, JP-A-55-48270, JP-A-58-160378, JP-A-58-1
83771). This aqueous dispersion containing synthetic rubber latex and tackifier resin has a solid content of 1
00 parts by weight and 50 to 100 parts by weight of tackifying resin are generally used.They exhibit good adhesive properties at a measurement temperature of 20 to 23°C, but exhibit poor adhesion at a temperature of 0°C. As for the force, a satisfactory value was not obtained. In addition, products that have adhesive properties only with rubber latex polymers without the presence of tackifying resin have also been proposed (JP-A-56-145909, JP-A-57-1999).
57707). However, this material has the drawback of extremely low adhesion to polyethylene.

As described above, the conventional technology cannot cope with the ever-increasing printing speed of coated paper, and there is a strong need for the emergence of copolymer latex as a binder that enables the production of high-quality coated paper. The current situation is that Furthermore, copolymer latexes with high adhesive strength are similarly desired for carpets and adhesives.

Problems to be Solved by the Invention Under these circumstances, the present invention aims to improve the balance between pick strength and other properties in coated printing paper, and the adhesive strength in carpet pack sizing and adhesives. This was done with the aim of providing a high-performance copolymer latex for improving the quality of the product.

Means for Solving the Problems As a result of intensive research to develop the above-mentioned high-performance copolymer latex, the present inventors discovered that the monomers were copolymerized with a conjugated diene compound and an ethylenically unsaturated carboxylic acid. By using at least three monomers, possibly other monomers, and by the presence of a specific solvent and a chain transfer agent during emulsion polymerization of these monomers in an aqueous medium, The present inventors have discovered that it is possible to accomplish the following, and have completed the present invention based on this knowledge.

That is, the present invention produces a copolymer latex by emulsion polymerizing at least three monomers, a conjugated diene compound, an ethylenically unsaturated carboxylic acid, and another monomer copolymerizable in an aqueous medium. A non-polymerizable, water-insoluble solvent that is compatible with at least one of the monomers and capable of swelling or dissolving the resulting copolymer, and a chain transfer agent that is compatible with this solvent. The present invention provides a method for producing a copolymer latex, characterized in that the reaction is carried out in the presence of a copolymer latex, and a copolymer latex obtained by this method.

The present invention will be explained in detail below.

A feature of the present invention is that a non-polymerizable, water-insoluble solvent is used when producing the copolymer Late Nox by emulsion polymerization. Non-polymerizable herein means not having a radically reactive double bond, and water-insoluble means that the solubility in water is less than 5% by weight. Further, it is desirable that the solvent is less likely to cause radical reactions other than polymerization reactions, that is, chain transfer reactions, and particularly desirably has a chain transfer constant of 10-'' or less in solution polymerization of styrene at 60°C.

In the present invention, the solvent is required to be compatible with at least one monomer used in the polymerization and to be able to swell or dissolve the copolymer produced. Compatibility here means that the solubility in the monomer is 5% by weight or more.

In addition, swelling here means that the degree of swelling shown below is 1.5 or more, and dissolution means that the amount of insoluble matter shown below is 5% by weight.
It means that:

The degree of swelling and the amount of insoluble matter are measured by the following method. That is, the obtained copolymer latex was adjusted to have a solid content concentration of 50% by weight, and after coating it on a glass plate with a caster having a thickness of 0.5 + IIm, it was coated at a temperature 30°C or more higher than the minimum film forming temperature. The film was dried by heating for 48 hours, and then the obtained film 0.59 was accurately weighed, and the solvent 30-
Add and let stand for 7 days. Next, this was filtered through a #325 wire mesh, the residue on the mesh was weighed to determine the weight of the wet residue, and then the solvent was evaporated by vacuum drying and the weight of the dry residue was measured.
The degree of swelling and the amount of insoluble matter are calculated using the following formula.

Since the solvent is removed by heating under reduced pressure after the polymerization is completed, its boiling point is 150°C or lower, preferably 100°C or lower.
Advantageously, the temperature is below 0.degree. The amount of the solvent used is usually selected within the range of 0.1 to 50 parts by weight per 100 parts by weight of the monomer. If this amount is less than 0.1 part by weight, the effect of the present invention will not be fully exhibited, and if it exceeds 50 parts by weight, the polymerization yield will tend to decrease and the amount of solvent recovered will increase, which is economically disadvantageous. becomes.

There are no particular restrictions on the method of using this solvent, such as - pre-addition method, method of additional addition together with other monomers or polymerization modifiers or separately, intermittent addition method, or continuously changing the addition rate. Any method can be selected and used from among the concentration gradient addition methods and the like. In the case of the pre-addition method, it can also be absorbed into the seed latex in advance.

Examples of the solvent include linear alkanes such as pentane, hexane, and heptane, cyclic alkanes such as cyclohexane, aromatic hydrocarbons such as benzene and toluene, and carboxylic acid esters such as heptyl acetate. These solvents can be used alone or in combination of two or more. When using a mixed solvent here, it is necessary that the properties of the mixed liquid satisfy the above-mentioned conditions of water insolubility, compatibility with the monomer, and swelling and solubility of the copolymer. .

In the present invention, if desired, less than 5 parts by weight of a non-polymerizable water-soluble solvent can be used together with the above-mentioned solvent or mixed solvent, based on 100 parts by weight of the monomer. Examples of the non-polymerizable water-soluble solvent include alcohols such as TLF methanol, ethanol, propatool, ingropanol, butanol, amyl alcohol, ethylene glycol, propylene glycol, butanediol, and glycerol, dioxane, acetone, Ketones such as methyl ethyl ketone, cyclic ethers such as tetrahydro-7rane, cellosolves such as cellosolve, methyl selon rub, butyl cellosolve, nitriles such as acetonitrile,
N. Amides such as N-dimethylformamide and the like can be mentioned.

In the present invention, it is necessary to use a chain transfer agent that is compatible with the non-polymerizable water-insoluble solvent. Compatibility here means that the solubility of the chain transfer agent in the solvent is 5% by weight or more. Such chain transfer agents include, for example, t-dodecylmercaptan, alkylmercaptans such as decylmercaptan and mercaptoethanol, thioglycolic acid esters such as ethylhexyl thioglycolate, pentaerythritol tetrathioglycolate, terpinolene, dipentene, t-terpinene, and Examples include halogenated hydrocarbons such as carbon tetrachloride, sulfides, and the like.

There are no particular restrictions on the method of using these chain transfer agents, and known methods such as a pre-addition method, a continuous addition method, an intermittent addition method, and a concentration gradient addition method in which the addition rate is sequentially changed are used. Can be used.

The conjugated diene compounds used in the present invention include:
For example, butadiene, inglene, 2-chloro-1,3-
Examples include butadiene. These conjugated diene compounds may be used alone or in combination of two or more, and the amount used is 5% by weight or more based on the weight of all monomers, preferably in terms of cohesive force. The content is selected from 20 to 70% by weight. If the amount used is less than 5% by weight, the obtained polymer will be too brittle, and if it exceeds 70% by weight, it will be too soft, and in either case, a high cohesive force will not be obtained, and the purpose of the present invention will not be fully achieved. .

Examples of the ethylenically unsaturated carboxylic acid used in the present invention include acrylic acid, methacrylic acid, itaconic acid, maleic acid, hexamaric acid, and crotonic acid. These ethylenically unsaturated carboxylic acids may be used alone or in combination of two or more, and the amount used is 0.2% by weight or more based on the weight of all monomers,
It is preferably selected within the range of 0.2 to 15% by weight. If this amount is less than 0.2% by weight, the dispersion stability of the latex will not be sufficient, causing various problems during paint preparation and coating, and the shock strength will also be low, while if it exceeds 15% by weight, the latex and paint will l, % is unfavorable because it tends to increase the viscosity too much and reduce water resistance.

Other copolymerizable monomers used in the present invention include aromatic monovinyl compounds, divinyl compounds, acrylic esters, methacrylic esters, vinyl cyanide compounds, ethylenic amides, etc.
Among these, aromatic monovinyl compounds and divinyl compounds are particularly preferred.

As the aromatic monovinyl compound or divinyl compound,
Examples include styrene, α-methylstyrene, chlorostyrene, alkylstyrene, divinylbenzene, etc. Examples of acrylic acid esters and methacrylic acid esters include methyl, ethyl, propyl, butyl, 2-ethylhexyl of acrylic acid or methacrylic acid, Examples include hydroxyethyl, glycidyl ester, and ethylene glycol diacrylate or dimethacrylate. Examples of vinyl cyanide compounds include acrylonitrile and methacrylaterile, and examples of ethylenic amides include acrylamide, methacrylamide, N-methylolacrylamide, and N-methylolmethacrylamide.

Furthermore, in addition to these monomers, vinyl esters such as vinyl acetate, vinyl chloride, vinyl halides such as vinylidene chloride, aminoethyl acrylate or methacrylate, dimethylaminoethyl acrylate or methacrylate, diethylaminoethyl acrylate or methacrylate, etc. Ethylenic amines, sodium styrene sulfonate, etc. can also be used.

One type of these copolymerizable monomers may be used, or two types of these copolymerizable monomers may be used.
You may use combinations of more than one species.

The copolymer latex in the present invention is obtained by emulsion polymerization of the conjugated diene compound and another monomer copolymerizable with the ethylenically unsaturated carboxylic acid in an aqueous medium. There are no particular restrictions on this emulsion polymerization method, and conventionally known methods such as water and the above monomer,
In a dispersion system whose basic components are a solvent, a chain transfer agent, a surfactant, a radical polymerization initiator, and other additive components used as necessary, the monomers are polymerized to form an aqueous copolymer particle. A method of producing a dispersion, that is, a copolymer latex, etc. is used. The concentration of the copolymer in this copolymer latex is usually selected in the range of 40 to 60% by weight, and the average particle size is 0.05 to l p ra
, preferably in the range from 0.07 to 0.3 p m. The average particle size can be adjusted by adjusting the proportion of surfactant and seed latex used, and generally, the higher the proportion used, the smaller the average particle size of the resulting copolymer latex tends to be.

Examples of the surfactants include anionic surfactants such as fatty acid soaps, rosin acid soaps, alkyl sulfonates, dialkylaryl sulfonates, alkyl sulfosuccinates, polyoxyethylene alkyl sulfates, and polyoxyethylene alkylaryl sulfates. Nonionic surfactants such as activators, polyoxyethylene alkyl ether aryl ethers, polyoxyethylene rubitan fatty acid esters, and oxyethylene oxypropylene block copolymers can be mentioned. This surfactant is usually used as an anionic surfactant alone or in an anionic/nonionic mixed system, and the amount used is usually in the range of 0.05 to 2% by weight based on the weight of the total monomer. To be elected.

The radical polymerization initiator has the effect of causing addition polymerization of monomers by radical decomposition using heat or a reducing substance. Examples of such a radical polymerization initiator include water-soluble or oil-soluble beroxonisulfuric acid. Salts, peroxides, azobis compounds, etc., specifically potassium beroquinisulfate, sodium berooxodisulfate, ammonium beloquinisulfate, hydrogen peroxide, t-butyl hydroperoxide, benzoyl peroxide, 2,2-azobisisobutyronitrile , cumene hydroperoxide, etc.
Among these, beroxonisulfate is particularly preferred. The amount of the polymerization initiator used is usually selected within the range of 0.2 to 1.5% by weight based on the weight of all monomers.

The polymerization temperature in this emulsion polymerization is usually 60 to 90'C.
However, if it is desired to accelerate the polymerization rate or polymerize at a lower temperature, a reducing agent such as acidic sodium sulfite, ascorbic acid or its salts, erythorbic acid or salts, or Rongalit may be combined with the polymerization initiator. A so-called redox polymerization method can be employed.

In the present invention, various polymerization regulators such as sodium hydroxide, potassium hydroxide, sodium hydrogen carbonate, sodium carbonate, disodium hydrogen phosphate, etc. can be used as desired.
Various chelating agents such as H regulators and sodium ethylenediaminetetraacetate can be added.

When the copolymer latex of the present invention is used as a binder for paper coatings, it can be prepared using a conventional method such as adding an inorganic pigment or inorganic pigment to water in which a dispersant is dissolved.
A method can be adopted in which the copolymer latex is added and mixed together with organic pigments, water-soluble polymers, and various additives to form a homogeneous dispersion. This paper coating paint can be applied to base paper by a conventional method using various blade coaters, roll coaters, etc.

Effects of the Invention According to the present invention, it is possible to easily create a high-performance copolymer latex that can further improve the balance between pick strength and other properties in coated printing papers, and the adhesive strength in carpet back sizing and adhesives. can be obtained.

Examples Next, the present invention will be explained in more detail with reference to examples.
The present invention is not limited in any way by these examples.

In addition, each characteristic was calculated|required as follows.

(1) Properties of copolymer latex (a) Average particle size Light scattering particle size analyzer (Model 600 manufactured by CN Wood)
The average particle diameter of the copolymer latex was measured using 0).

(b) Gel fraction and swelling degree of copolymer The copolymer latex was uniformly coated on a polypropylene film using a No. 26 wire bar and dried for 1 hour in a dryer at 50°C to form a film. .

Next, this copolymer latex film was peeled off, approximately 0.5 g was accurately weighed using an analytical balance, and the mixture was immersed in a container containing 300 cc of toluene and stirred at room temperature for 6 hours using a shaker. Afterwards, the contents were precisely weighed in advance.325
Filter through a mesh wire mesh and weigh the residue remaining on the wire mesh. After that, it is dried in a dryer at 50° C. for 2 hours, and the gel fraction and degree of swelling are determined by the following formula.

Gel fraction (weight %) Swelling degree (2) Paper coating performance (a) Blister resistance Printing ink (manufactured by Dainippon Ink Co., Ltd., Webb) on both sides of coated paper using an R1 printing tester (manufactured by Mei Seisakusho) Zett yellow) 0.3 cc is printed all over. This printed coated paper is cut to an appropriate size, and the test piece is immersed in a silicone oil constant temperature bath adjusted to a predetermined temperature to observe whether or not blisters occur. This test is performed by varying the temperature of the thermostatic chamber, and the lowest temperature at which blistering is observed is determined. The higher the temperature, the better the blister resistance.

(b) Printing ink (manufactured by Togun Shiki Co., Ltd.,
SD Susu--Deluxe 5o Beni B; Tack value 1 g) 0
．． Overprint 4cc 5 times, trace the picking state that appears on the rubber roll onto another mount, and observe the degree of picking. Evaluation was performed using the IO point evaluation method, and the fewer the picking phenomenon, the higher the score.

(c) Wet pick strength Using an RI printing tester, moisten the surface of the coated paper with a water absorption roll, and then apply 0.4 cc of printing ink (manufactured by Togun Shiki Co., Ltd., SD Susu Deluxe 50tB; tack value 18). After printing once, the picking state that appears on the rubber roll is traced onto another mount and the extent of the picking is observed. Evaluation was performed using the IO point evaluation method, and the less the picking phenomenon was, the higher the score was.

Halftone dot reproducibility Printed using a Ministry of Finance type gravure tester, and the missing halftone dot rate was counted. Evaluation was performed using a 10-point evaluation method, and the smaller the missing rate, the higher the score.

(3) Carpet back sizing performance Peel strength and thread removal strength were determined in accordance with JIS L-1021. The higher the average value, the better.

(4) Adhesive performance (a) High-temperature cohesive force Place the adhesive sample on a stainless steel plate at 251R+++×251n.
Paste it by making one reciprocation of a 2 kg roller with a size of
The shear force was measured at a rate of 21 IITR/1 Ilin in an atmosphere of 0°C.

(b) Place an adhesive sample with a low-temperature adhesive strength of 25 mm and a length of 250 mm face up in a ring (
500mm/m under O'C atmosphere.
The corrugated pole surface is brought into contact with almost zero pressure at a speed of in. 3 seconds after contact, same < 500mm/
The peel adhesive strength was measured when peeled off at a speed of min.

(c) PE adhesiveness In an atmosphere of 23°C, an adhesive sample with a width of 25 mm was pasted to a low-density PE board that did not contain additives by moving it back and forth once with a 2 kg roller, and 20 minutes after pasting. , 180° building strength was measured at a speed of 500 m++/min.

Examples 1 to 25, Comparative Example 1-1 4 parts by weight of an aqueous dispersion of seed particles with a diameter of 0.04 μm (seed solid content concentration 25% by weight) was placed in a pressure-resistant reaction vessel equipped with a stirring device and a temperature control jacket. 70 parts by weight of water, 0.2 parts by weight of sodium lauric sulfate, and 2.5 parts by weight of 7-maric acid were added to a colander, and the internal temperature was raised to 80°C. An oily mixture containing a transfer agent and a non-polymerizable water-insoluble solvent, and water 15
parts by weight, 1 part by weight of sodium beloxonisulfate, 0.2 parts by weight of sodium hydroxide, 0.2 parts by weight of sodium lauric sulfate.
An aqueous solution starting from 1 part by weight was added at a constant flow rate over 4 hours and 5 hours, respectively. After maintaining the temperature at 80°C for 1 hour, it was cooled, and the resulting copolymer latex was adjusted to a po of 7 with sodium hydroxide, and then subjected to a steam stripping method to remove unreacted monomers and non-polymerizable materials. The water-insoluble solvent was removed and the mixture was filtered through a 200-mesh filter cloth.

Note that all copolymer latexes were adjusted so that the final solid content concentration was 50% by weight.

Table 1 shows the average particle diameter and gel fraction of these copolymer latexes.

Application Example 1 The copolymer latexes prepared in Examples and Comparative Examples were evaluated for their performance as binders for paper coating. The result is displayed in the fourth display.

The coating material had the formulation shown in Table 2 and was prepared using a high-speed stirrer with an amount of water that gave a nonvolatile content concentration of 63% by weight. The pH of the paint was adjusted to 9.0 with aqueous ammonia. Table 3 shows the conditions for preparing coated paper using this paint.

From Table 4, it can be seen that the coated paper using the copolymer latex of the present invention as a binder is highly balanced in bulk strength and other physical properties.

Table (Note) l) “Ultra White 90” manufactured by Engelhard
” “Ultra Coat” manufactured by Engelhard Co., Ltd. “
Niskaran #1500J Toa Gobo Chemical Co., Ltd. “Aron T
-40J "Sumilets 636" manufactured by Sumitomo Chemical Co., Ltd. rMs4600J manufactured by Nihon Shokuhin Kogyo Co., Ltd. Application Example 2 Performance evaluation as a binder for carpet back sizing was performed on the copolymer latexes prepared in Examples and Comparative Examples. The results are shown in Table 7.

The adhesive paint had the formulation shown in Table 5, and was prepared using a high-speed stirrer with an amount of water that gave a nonvolatile content concentration of 70% by weight. Table 6 shows the conditions for preparing a carpet using this paint.

Table 7 shows that the carpets using the copolymer latex of the present invention as a binder have highly improved peel strength and thread removal strength.

Table 2) Toagosei Kagaku Co., Ltd. "Aron T-40J3) Kuraray Co., Ltd. rPV A-217J Table Application Example 3 Performance as an adhesive for the copolymer latex prepared in the Examples and Comparative Examples was evaluated.

Approximately 0.5 parts by weight of sodium polyacrylate was added to the obtained copolymer latex to give a viscosity of approximately 10.000c.
PS, and after coating it uniformly on release paper at a coating weight of about 45 dry g/ill, it was dried with hot air at 120°C for 2.5 minutes. The dried coating film on the release paper was stretched. An adhesive sample was obtained by pressing the dried coating film onto the corona discharge treated surface of a polypropylene film (about 80 μm thick) and transferring the dry coating onto the polypropylene film.
After curing for one week at a relative temperature of 65%, the adhesive properties were evaluated.

The results are shown in Table 8.

Table 8

Claims (1)

[Claims] 1. A copolymer latex is obtained by emulsion polymerizing at least three monomers, a conjugated diene compound, an ethylenically unsaturated carboxylic acid, and another monomer copolymerizable in an aqueous medium. During production, a non-polymerizable, water-insoluble solvent that is compatible with at least one of the monomers and capable of swelling or dissolving the resulting copolymer, and a chain transfer compatible with this solvent. A method for producing a copolymer latex, which comprises reacting in the presence of a copolymer latex. 2. A copolymer latex obtained by the method according to claim 1.