JP5426700B2 - Copolymer latex and composition containing the copolymer latex - Google Patents

Description

  The present invention relates to a copolymer latex. Specifically, the present invention relates to a copolymer latex that is excellent in adhesive strength and odor and useful as a binder.

  It is well known that diene copolymer latex is widely used as various adhesives (binders) including paper processing field and carpet backsizing. The performance required of binders varies according to each application, but diene copolymer latex, which is a synthetic rubber latex, can relatively easily control monomer composition changes and copolymer molecular weight. Yes, it is possible to meet various demands.

For example, in the paper processing field, coated paper is used for a large number of printed materials because of its high printing effect. Coated paper is used on many pages of quarterly and monthly periodicals, direct mail in the mail order business, and product catalogs. As printing speeds have increased, demands on the properties of coated paper from each market have increased.
In general, coated paper is produced by applying a paper coating composition onto the surface of a coated base paper and drying it. A composition for paper coating is a water-based paint comprising a pigment dispersion in which a white pigment such as clay or calcium carbonate is dispersed in water, a binder for adhering and fixing the pigments to each other and a base paper, and other additives. It is. As the binder, a synthetic emulsion binder represented by styrene-butadiene copolymer latex and a natural binder represented by starch and casein are used. Among them, styrene-butadiene copolymer latex has a large degree of freedom in quality design and is widely used as the most suitable binder for paper coating compositions today. However, it is known that it affects the performance of the composition for paper coating, the operability at the time of preparing the coated paper, the quality of the final coated paper product, such as the surface strength and printing gloss.

  In order to improve the quality of the coated paper product such as the surface strength, for example, Japanese Patent Application Laid-Open No. 2006-152484 (Patent Document 1) uses a core-shell type copolymer latex obtained by multistage polymerization having an average particle diameter of 150 nm or less. Thus, a technique for providing a matte coated paper with good printing gloss, ink set and ink drying properties has been introduced. In JP-A-9-31894 (Patent Document 2), a monomer mixture containing the total amount of unsaturated dicarboxylic acid and methacrylic acid is polymerized in the first stage of polymerization, and then the second and subsequent stages are polymerized. According to the composition for paper coating using the copolymer latex obtained in this way, a coated paper for off-wheel printing excellent in surface strength during printing, water resistance, ink inking property, and blister resistance is obtained. There is a technical disclosure to be made. Furthermore, in JP 2008-248446 A (Patent Document 3), by defining the contact angle of the copolymer latex film with soybean oil, the printability such as surface strength at the time of printing, printing gloss, ink set, etc. It is introduced that it is possible to provide a coated paper that is superior to the above, and multi-stage polymerization is preferred for obtaining the copolymer latex.

Also in the carpet field, a synthetic emulsion binder represented by styrene-butadiene copolymer latex has been used as a binder for bonding fibers and fibers to a base fabric. It is used for things. In recent years, various studies have been made to obtain these adhesive strengths with a smaller amount of binder for the purpose of cost reduction.
For example, in Japanese Patent Application Laid-Open No. 3-121179 (Patent Document 4), an aliphatic conjugated diene monomer is emulsion-polymerized in the presence of a chain transfer agent such as α-methylstyrene dimer or terpinolene to improve the texture and adhesive strength. Techniques have been clarified that result in latex that gives excellent carpet.

On the other hand, the odor in coated paper and textile products of final products using diene copolymer latex as a binder is one of the issues that need to be improved in some cases because the product value is lost just because the odor is generated. is there.
For example, as a method for improving the surface strength and ink inking property as well as the odor of coated paper products, JP-A-2001-248098 (Patent Document 5) describes a monomer composition to be copolymerized, and 1, 3- There is a technical disclosure that defines the residual amount of 4-phenylcyclohexene, which is a reaction product of butadiene and styrene, in the latex.
However, these various improvement techniques have not yet reached a level that sufficiently satisfies the demanded physical properties that are increasing daily as binders in various applications, and further improvements are strongly demanded.

JP 2006-152484 A

JP 9-31894 A

JP 2008-248446 A

Japanese Patent Laid-Open No. 3-121179

JP 2001-248098 A

  The present invention is obtained by polymerizing an aliphatic conjugated diene monomer, a specific acrylic acid alkyl ester monomer, an ethylenically unsaturated carboxylic acid monomer, and other monomers copolymerizable therewith. A copolymer latex characterized by having an average particle size in a specific range and a residual amount of a specific acrylate monomer being not more than a specific amount, and having excellent adhesive strength and odor Is intended to provide.

  10 to 60 parts by weight of an aliphatic conjugated diene monomer, 5 to 40 parts by weight of an alkyl acrylate monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid, 1 to 1 of an ethylenically unsaturated carboxylic acid monomer A copolymer latex obtained by emulsion polymerization of 15 parts by weight of a monomer (a total of 100 parts by weight of monomers) composed of 20 to 84 parts by weight of other monomers copolymerizable therewith. The residual amount in the copolymer latex of an alkyl acrylate ester monomer consisting of an alcohol having 5 or more carbon atoms and acrylic acid having an average particle size of 50 to 150 nm by photon correlation method is The solid content is 300 ppm or less.

  Since the copolymer latex of the present invention is excellent in adhesive strength and odor, a coated paper obtained by coating a paper coating composition using the copolymer latex as a binder is used at the time of printing. Excellent pick strength and odor. Further, by using the copolymer latex as a carpet backing agent, it is possible to obtain a carpet having an excellent balance of peel strength, pile pull-out strength and texture (soft feeling when touched) and excellent odor.

The copolymer latex of the present invention comprises an aliphatic conjugated diene monomer, an acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid, an ethylenically unsaturated carboxylic acid monomer, and these It can be obtained by emulsion polymerization of other copolymerizable monomers.
Aliphatic conjugated diene monomers include 1,3-butadiene, 2-methyl-1,3-butadiene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, substituted Examples thereof include linear conjugated pentadienes, substituted and side chain conjugated hexadienes and the like, and these can be used alone or in combination. In particular, the use of 1,3-butadiene is preferred.
The aliphatic conjugated diene monomer needs to be used in the range of 10 to 60 parts by weight in 100 parts by weight of all monomers. If it is less than 10 parts by weight, the dry pick strength of the coated paper and the texture of the carpet are lowered. If the amount exceeds 60 parts by weight, the carpet peeling / punching strength decreases, and the odor in the final product obtained such as coated paper or carpet deteriorates. More preferably, it is 15 to 50 parts by weight.

Examples of the acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid include cyclohexyl acrylate, 2-ethylhexyl acrylate, isononyl acrylate, stearyl acrylate, isobornyl acrylate, and the like. Or 2 or more types can be used. In particular, the use of 2-ethylhexyl acrylate is preferable.
The alkyl acrylate monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid needs to be used in the range of 5 to 40 parts by weight in 100 parts by weight of all monomers. If the alkyl ester monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid is less than 5 parts by weight, the dry pick strength is lowered when the coated paper is used, and the texture of the carpet is lowered. This is because the copolymer latex is excessively crosslinked. When the amount of the alkyl acrylate ester monomer consisting of an alcohol having 5 or more carbon atoms and acrylic acid exceeds 40 parts by weight, the wet topic strength is reduced when coated paper is used, and the peeling / punching strength is reduced for carpets. . More preferably, it is 5 to 30 parts by weight.

Examples of the ethylenically unsaturated carboxylic acid monomer include monobasic acids or dibasic acids (anhydrides) such as acrylic acid, methacrylic acid, crotonic acid, maleic acid, fumaric acid, and itaconic acid.
The ethylenically unsaturated carboxylic acid monomer needs to be used in the range of 1 to 15 parts by weight per 100 parts by weight of the total monomers. When the amount of the ethylenically unsaturated carboxylic acid monomer is less than 1 part by weight, the wet topic strength decreases when the coated paper is used, and the peeling / punching strength decreases when the carpet is used. On the other hand, when the ethylenically unsaturated carboxylic acid monomer exceeds 15 parts by weight, the viscosity of the latex becomes high and handling becomes difficult. Preferably it is 1.5-10 weight part.

  As the above aliphatic conjugated diene monomer, an alkyl acrylate monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid, or another monomer copolymerizable with an ethylenically unsaturated carboxylic acid monomer Is an alkenyl aromatic monomer, an unsaturated carboxylic acid alkyl ester monomer (excluding an acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid), a vinyl cyanide monomer, a hydroxy Examples thereof include an unsaturated monomer containing an alkyl group and an unsaturated carboxylic acid amide monomer.

  Examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyltoluene, divinylbenzene, and the like, and these can be used alone or in combination. In particular, use of styrene is preferable.

Unsaturated carboxylic acid alkyl ester monomers (excluding acrylic acid alkyl ester monomers consisting of alcohols with 5 or more carbon atoms and acrylic acid) include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate Acrylic acid alkyl ester monomer consisting of alcohol and acrylic acid having 4 or less carbon atoms, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, dimethyl maleate, diethyl maleate, dimethyl Examples include itaconate, monomethyl fumarate, monoethyl fumarate, and the like, and one or more of them can be used. In particular, the use of methyl methacrylate is preferred.
When an acrylic acid alkyl ester monomer composed of an alcohol having 4 or less carbon atoms and acrylic acid is used, the odor of the final product obtained tends to be lowered, so that it comprises an alcohol having 4 or less carbon atoms and acrylic acid. When using an acrylic ester, the amount used is preferably less than 1 part by weight, more preferably less than 0.5 part by weight.

  Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile, and the like, and one or more of these can be used. In particular, the use of acrylonitrile or methacrylonitrile is preferred.

  Examples of unsaturated monomers containing a hydroxyalkyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, and 3-chloro-2-hydroxypropyl. Methacrylate, di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate, and the like. Or 2 or more types can be used. In particular, the use of β-hydroxyethyl acrylate is preferred.

  Examples of the unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N-dimethylacrylamide, and the like, and one or more of these may be used. it can. Particularly preferred is the use of acrylamide or methacrylamide.

  Further, in addition to the above monomers, any of the monomers used in ordinary emulsion polymerization such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride can be used.

  These other copolymerizable monomers need to be used in the range of 20 to 84 parts by weight in 100 parts by weight of the total monomers. If the amount of these other copolymerizable monomers is less than 20 parts by weight, the wet topic strength is lowered when the coated paper is used, and the peeling / punching strength is lowered in the carpet. If it exceeds 84 parts by weight, the dry pick strength is lowered when coated paper is used, and the texture of carpet is lowered. More preferably, it is 30-70 weight part.

  The average particle size of the copolymer latex by the photon correlation method needs to be in the range of 50 to 150 nm. If it is less than 50 nm, the viscosity of the latex becomes high and handling becomes difficult. If it exceeds 150 nm, the adhesive strength (dry pick strength when coated paper, peel / extract strength for carpet) and odor are reduced. Preferably, it is 50-130 nm.

  The copolymer latex of the present invention requires that the residual amount of the alkyl acrylate ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid be 300 ppm or less based on the solid content of the copolymer latex. is there. If it exceeds 300 ppm, the odor of the final product obtained will deteriorate. As a method of setting the residual amount of the alkyl acrylate monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid to 300 ppm or less based on the solid content of the latex, 1) A method of adding an alkyl acrylate monomer composed of 5 or more alcohols and acrylic acid to the first half of the polymerization, 2) a method of extending the polymerization after completion of the monomer addition and increasing the polymerization conversion rate, and 3) completion of the polymerization. The method of removing by later steam distillation etc. is mentioned. From the viewpoint of energy saving, the methods 1) and 2) are preferable, and these methods can be combined. Further, it is more preferable from the viewpoint of odor that the residual amount of the alkyl acrylate monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid is 200 ppm or less based on the solid content of the latex.

  The method for polymerizing the copolymer latex of the present invention is preferably multistage polymerization of two or more stages. The method for adding the monomer and other components is not particularly limited, and the method for adding the monomer may be any of the divided addition method and the continuous addition method. In emulsion polymerization, known emulsifiers, polymerization initiators, chain transfer agents, hydrocarbon solvents, electrolytes, and the like can be used.

  Emulsifiers include higher alcohol sulfates, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, dehydroabietic acid salts, formalin condensates of naphthalene sulfonic acid, nonionic Nonionic surfactants such as surfactant anionic surfactants such as sulfate salts, polyethylene glycol alkyl ester type, alkylphenyl ether type, alkyl ether type, etc. are used, and one or more of these are used. can do.

  As polymerization initiators, water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate, ammonium persulfate, cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide, acetyl peroxide, diisopropylbenzene Oil-soluble polymerization initiators such as hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, or redox polymerization initiators can be used as appropriate. In particular, it is preferable to use potassium persulfate, sodium persulfate, cumene hydroperoxide, or t-butyl hydroperoxide.

  Examples of the chain transfer agent include xanthogen compounds such as alkyl mercaptan, dimethylxanthogen disulfide and diisopropylxanthogen disulfide, thiuram compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide, and 2,6-di-t. -Phenol compounds such as butyl-4-methylphenol and styrenated phenol, allyl compounds such as allyl alcohol, halogenated hydrocarbon compounds such as dichloromethane, dibromomethane and carbon tetrabromide, α-benzyloxystyrene, α-benzyl Vinyl ethers such as oxyacrylonitrile and α-benzyloxyacrylamide, triphenylethane, pentaphenylethane, acrolein, methacrolein, thioglycolic acid Thiomalate, 2-ethylhexyl thioglycolate, Tapinoren, alpha-methyl styrene dimer and the like, can be used one or more of them.

  Examples of hydrocarbon solvents include saturated hydrocarbons such as pentane, hexane, heptane, octane, cyclohexane, cycloheptane, and unsaturated hydrocarbons such as pentene, hexene, heptene, cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, and 1-methylcyclohexene. Hydrocarbon compounds such as hydrocarbons, aromatic hydrocarbons such as benzene, toluene and xylene can be used. In particular, cyclohexene and toluene, which have a moderately low boiling point and can be easily recovered and reused by steam distillation after the completion of polymerization, are suitable from the viewpoint of environmental problems, although they are different from the object of the present invention.

  For the polymerization of the copolymer latex of the present invention, known additives such as oxygen scavengers, chelating agents, and dispersing agents may be used as necessary, and these are not particularly limited in both type and amount used. An appropriate amount can be used as appropriate. Furthermore, known additives such as antifoaming agents, anti-aging agents, antiseptics, antibacterial agents, flame retardants, and UV absorbers may be used. I can do it.

The paper coating composition and the carpet backing composition of the present invention use the copolymer latex of the present invention as a binder.
Examples of the pigment used in the paper coating composition of the present invention include known pigments such as kaolin clay, calcium carbonate, talc, barium sulfate, titanium oxide, aluminum hydroxide, zinc oxide, and satin white. Alternatively, organic pigments such as polystyrene latex can be used alone or in combination. The content of the copolymer latex in the paper coating composition is preferably 1 to 20 parts by weight (solid content) with respect to 100 parts by weight (solid content) of the pigment. If the content of the copolymer latex is less than 1 part by weight, it is not preferable because the pigment cannot be sufficiently adhered, and if it exceeds 20 parts by weight, the opacity and white paper gloss are lowered, and the cost of the composition for paper coating increases. This is not preferable.
Examples of the filler used in the carpet backing composition of the present invention include inorganic fillers such as calcium carbonate, aluminum hydroxide, magnesium hydroxide, clay, barium sulfate, silicic acid, silicate, titanium oxide, magnesium carbonate, and calcium carbonate. Can be used alone or in combination. The usage ratio of the copolymer latex and the inorganic filler is preferably 30 to 800 parts by weight (solid content) of the inorganic filler with respect to 100 parts by weight (solid content) of the copolymer latex. If the amount of the inorganic filler is less than 30 parts by weight, an adhesive composition having a high solid content cannot be obtained and the drying rate is lowered, and the cost is increased. Therefore, it is not preferable. More preferably, it is 100-700 weight part.

  If necessary, modified starches such as starch, oxidized starch and esterified starch, natural binders such as soybean protein and casein, or water-soluble synthetic binders such as polyvinyl alcohol and carboxymethyl cellulose may be used.

  In preparing the composition of the present invention, further auxiliary agents such as a dispersant (sodium pyrophosphate, sodium polyacrylate, sodium hexametaphosphate, etc.), an antifoaming agent (polyglycol, fatty acid ester, phosphate ester) , Silicone oil, etc.), leveling agents (funnel oil, dicyandiamide, urea, etc.), preservatives, mold release agents (calcium stearate, paraffin emulsion, etc.), fluorescent dyes, color water retention agents (carboxymethylcellulose, sodium alginate, etc.), Thickeners (sodium polyacrylate, carboxymethylcellulose, etc.), foaming agents (surfactants, etc.), colorants (coloring pigments, etc.), flame retardants, anti-aging agents, stabilizers, vulcanization accelerators, crosslinking agents, charging You may add an inhibitor, a pH adjuster, etc. as needed.

Further, as a method for applying the paper coating composition to the coated paper, any known technique such as an air knife coater, blade coater, roll coater, bar coater, curtain coater or the like can be used. There is no problem. Further, after coating, the coated paper is obtained by drying and finishing by calendering or the like.
Although it does not specifically limit as a coating method of the composition for carpet backings, For example, a roll coat method, a direct coat method, an impregnation method, a spray method etc. are mentioned. About the drying after application | coating, although the method of heat-processing and drying is desirable, heating temperature is 80-160 degreeC, More preferably, it is 100-140 degreeC.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further more concretely, this invention is not limited to these Examples, unless the summary is exceeded. In the examples, parts and percentages indicating percentages are based on weight unless otherwise specified. In addition, various physical properties in the examples were evaluated by the following methods. The evaluation results are shown in Tables 1 to 3, respectively.

Measurement of average particle size of copolymer latex by photon correlation method Average particle size of copolymer latex was measured by photon correlation method. In the measurement, FPAR-1000 (manufactured by Otsuka Electronics) was used.

GC-2014 type manufactured by Shimadzu Corporation was used as a gas chromatograph for measuring the residual amount in the copolymer latex of cyclohexyl acrylate, 2-ethylhexyl acrylate, and butyl acrylate .
(1) Preparation of sample 1 g of copolymer latex was precisely weighed and dissolved in 25 ml of N, N-dimethylformamide, and 24 hours later, this was used as a measurement sample.
(2) Gas chromatograph measurement conditions Sample volume: 1 μL
Detector: FID
Injection temperature: 170 ° C
Detector temperature: 250 ° C
Column: length / inner diameter / film thickness (liquid layer) = 30 m / 0.25 mm / 0.5 μm (DB-WAX)
Carrier gas: He 1 mL / min Split ratio: 1/40
Column temperature: After holding at 70 ° C. for 5 minutes, the temperature is raised to 170 ° C. at 10 ° C./minute, further raised to 230 ° C. at 20 ° C./minute, and held for 10 minutes at 230 ° C. (3) Determination method Cyclohexyl acrylate Calibration curves were prepared using samples obtained by diluting 2-ethylhexyl acrylate and butyl acrylate with N, N-dimethylformamide, respectively. Using the calibration curve, cyclohexyl acrylate, 2-ethylhexyl acrylate and butyl acrylate remaining in the copolymer latex were quantified from the obtained gas chromatograph. The amount of residual monomer determined from the calibration curve was converted to the concentration (ppm) with respect to the solid content of the copolymer latex.

Measurement of gel content of copolymer latex A latex film is prepared at 80 ° C. Thereafter, about 1 g of the latex film is weighed to obtain Xg. This is put into 400 ml of toluene and swelled and dissolved for 48 hours. Then, this is filtered through a weighed 300-mesh stainless steel wire net, and then toluene is evaporated to dryness. The mesh weight is subtracted from the weight after drying, and the weight after drying of the sample is weighed to obtain Yg. The gel content was calculated from the following formula.
Gel content (%) = Y / X * 100

Evaluation of dry pick strength of coated paper The degree of picking when each coated paper sample is printed at the same time with an RI printing machine is judged with the naked eye, and relatively visually evaluated from grade 5 (excellent) to grade 1 (inferior). did.

Evaluation of wet pick strength of coated paper Picking when each coated paper sample is simultaneously printed with an ink roll immediately after applying dampening water to each coated paper sample with a molton roll using an RI printer. The degree of the above was determined with the naked eye, and was relatively visually evaluated from grade 5 (excellent) to grade 1 (poor).

Evaluation of odor of coated paper 10 g of each coated paper sample cut to about 3 cm square was placed in a 500 mL odor bottle, allowed to stand at 20 ° C. for 24 hours, and then heated at 70 ° C. for 30 minutes. Then, after cooling to room temperature, the odor of the sample was sniffed, and it was relatively evaluated from the fifth grade (less odor is good) to the first grade (more odor is bad) depending on the degree of odor. For each coated paper sample, 10 testers' judgments were averaged to obtain a test result.

Evaluation of peel strength and pull-out strength of carpet The pull-out strength and peel strength of the pile yarn were measured by a method based on the JIS L-1021 fibrous floor covering test method.

Evaluation of carpet texture The softness of each carpet specimen prepared was evaluated by touch.
○: Soft (soft)
Δ: Normal ×: Hard

Evaluation of carpet odor Each of the prepared carpet test pieces was cut into about 3 cm square, 10 g was placed in a 500 mL odor bottle, left at 20 ° C. for 24 hours, and then heated at 70 ° C. for 30 minutes. Then, after cooling to room temperature, the odor of the sample was sniffed, and it was relatively evaluated from the fifth grade (less odor is good) to the first grade (more odor is bad) depending on the degree of odor. For each coated paper sample, 10 testers' judgments were averaged to obtain a test result.

Synthetic copolymer latex 1-4, 11 of copolymer latex
In a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 1 part of potassium persulfate, monomers, emulsifiers, hydrocarbon solvents and chain transfer agents shown in the first stage of Table-1 or Table-2 The temperature was raised to 70 ° C., and the monomer, hydrocarbon solvent and chain transfer agent shown in the second stage of Table-1 or Table-2 were continuously added in 7 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the pH was adjusted to 7 using sodium hydroxide, and steam distillation was performed to obtain copolymer latexes 1 to 4 and 11.

Copolymer latex 5, 10
In a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 1 part of potassium persulfate, monomers, emulsifiers, hydrocarbon solvents and chain transfer agents shown in the first stage of Table-1 or Table-2 Was heated to 70 ° C., and the monomer and chain transfer agent shown in the second stage of Table-1 or Table-2 were continuously added in 4 hours. Furthermore, the monomer and chain transfer agent shown in the third row of Table-1 or Table-2 were continuously added in 4 hours. Furthermore, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, using sodium hydroxide, the pH was adjusted to 7, and steam distillation was performed to obtain copolymer latexes 5 and 10.

Copolymer latex 6
A pressure-resistant polymerization reactor equipped with a stirrer is charged with 150 parts of polymerization water, 1 part of potassium persulfate, the monomers, emulsifier, hydrocarbon solvent and chain transfer agent shown in the first stage of Table 1, 70 The temperature was raised to 0 ° C., and the monomer and chain transfer agent shown in the second row of Table 1 were continuously added in 6.5 hours. Furthermore, the monomer shown in the third row of Table 1 was continuously added in 1.5 hours. Furthermore, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the pH was adjusted to 7 using sodium hydroxide, and steam distillation was performed to obtain a copolymer latex 6.

Copolymer latex 7-9
In a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 1 part of potassium persulfate, monomers, emulsifiers, hydrocarbon solvents and chain transfer agents shown in the first stage of Table-1 or Table-2 The temperature was raised to 70 ° C., and the monomer and chain transfer agent shown in the second stage of Table-1 or Table-2 were continuously added in 7 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, using sodium hydroxide, the pH was adjusted to 7, and steam distillation was performed to obtain copolymer latexes 7 to 9.

Preparation of composition for paper coating According to the formulation shown below, the copolymer latex obtained above was blended to prepare a paper coating composition adjusted to pH 9.5 with sodium hydroxide.
(Formulation formulation of paper coating composition)
Formulated kaolin 40 parts Heavy calcium carbonate 60 parts Modified starch 2 parts Copolymer latex 8 parts ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・
Solid content 67%

Preparation and Evaluation of Coated Paper Coated paper (basis weight 55 g / m ² ) is coated with the above-mentioned composition for paper coating using a wire bar so that the coating amount per side is 10 g / m ^2. After being worked and dried, a calendar treatment was performed under conditions of a linear pressure of 60 kg / cm and a temperature of 50 ° C. to obtain a coated paper. The obtained coated paper was subjected to the above test and evaluated.

  As shown in Table 3, the coated paper obtained by coating the composition for paper coating using the copolymer latexes 1 to 7 according to the present invention has the dry pick strength and wet topic strength of the coated paper. Excellent odor.

In Comparative Example 8, the residual amount of the acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid exceeds the specified range of the present invention, and the odor of the obtained coated paper is inferior.
In Comparative Example 9, the amount of butadiene exceeds the upper limit of the specified range of the present invention, and the amount of acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid is less than the lower limit of the specified range of the present invention. The odor and dry pick strength of coated paper are inferior.
In Comparative Example 10, the particle size of the latex exceeds the upper limit of the specified range of the present invention, and the odor and dry pick strength of the coated paper are inferior.
In Comparative Example 11, the amount of acrylic acid alkyl ester monomer consisting of an alcohol having 5 or more carbon atoms and acrylic acid and the residual amount exceed the upper limit of the specified range of the present invention, the odor of the coated paper is inferior, wet Pick strength is greatly inferior.

Preparation of Composition for Carpet Backing According to the formulation shown below, the copolymer latex obtained above was blended to prepare a carpet backing composition.
(Composition formula of carpet backing composition)
Formulated latex latex 100 parts Heavy calcium carbonate 400 parts Sodium tripolyphosphate 1 part Styrenated phenol 0.5 parts Thickener
5 copies
・
・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・ ・
Solid content concentration 67%
Viscosity 40000 mPa · s

Fabrication and evaluation of carpet The above-mentioned carpet backing composition was uniformly applied to the back of a nylon fiber tufted carpet raw machine so that the solid content would be 700 g / m ^2, and a jute woven fabric was pasted together. After drying in a dryer for 15 minutes, a tufted carpet was obtained. The obtained tufted carpet was subjected to the above test and evaluated.

  As shown in Table-4, the tufted carpet obtained by applying the carpet backing composition using the copolymer latexes 1 to 7 according to the present invention is excellent in the balance of texture and peel strength / punching strength and odor. .

In Comparative Example 19, the residual amount of the acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid exceeds the specified range of the present invention, and the odor of the obtained tufted carpet is inferior.
In Comparative Example 20, the amount of butadiene exceeds the upper limit of the specified range of the present invention, and the amount of acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid is less than the lower limit of the specified range of the present invention. The odor, peel strength, pulling strength and texture of the tufted carpet are inferior.
In Comparative Example 21, the particle diameter of the latex exceeds the upper limit of the specified range of the present invention, and the odor, peel strength, and yarn removal strength of the tufted carpet are inferior.
In Comparative Example 22, the amount of acrylic acid alkyl ester monomer composed of an alcohol having 5 or more carbon atoms and acrylic acid and the residual amount exceeded the upper limit of the specified range of the present invention, and the odor, peel strength, and The pulling strength is inferior.

As described above, the copolymer latex of the present invention is excellent in adhesive strength and odor. A coated paper obtained by coating a paper coating composition using the copolymer latex is excellent in pick strength and odor during printing, and is useful as a binder and a composition for a paper coating composition It is.
In addition, the carpet obtained by applying a carpet backing agent using the copolymer latex has an excellent balance of peel strength / punching strength and texture, and has less carpet odor, and a carpet backing binder and carpet backing agent. Useful as. Further, it can also be used as a battery electrode binder, a wood adhesive binder, and a chipping-resistant bander.

Claims (7)

  10-60 parts by weight of an aliphatic conjugated diene monomer, 5-40 parts by weight of an acrylic acid alkyl ester monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid, 1-ethylenically unsaturated carboxylic acid monomer A copolymer latex obtained by emulsion polymerization of 15 parts by weight of a monomer (a total of 100 parts by weight of monomers) composed of 20 to 84 parts by weight of other monomers copolymerizable therewith. The residual amount of the alkyl acrylate ester monomer consisting of an alcohol having a carbon number of 5 or more and an acrylic acid is 300 ppm or less based on the solid content of the copolymer latex. Is a copolymer latex.   2. The copolymer latex according to claim 1, wherein the residual amount of the acrylate monomer comprising an alcohol having 5 or more carbon atoms and acrylic acid is 200 ppm or less, based on the solid content of the copolymer latex.   The copolymer latex according to claim 1 or 2, having an average particle diameter of 50 to 130 nm by a photon correlation method.   A copolymer latex according to any one of claims 1 to 3, wherein the copolymer latex is used as a binder of a paper coating composition.   A composition for paper coating, wherein the copolymer latex according to any one of claims 1 to 3 is used as a binder.   Copolymer latex according to any one of claims 1 to 3, which is used as a binder for a carpet backing composition.   The composition for carpet backing characterized by using the copolymer latex in any one of Claims 1-3 as a binder.