JP5602197B2 - Method for producing copolymer latex and copolymer latex - Google Patents

Description

  The present invention relates to a method for producing a copolymer latex, and a copolymer latex obtained by the method.

Butadiene copolymer latex (copolymer latex based on 1,3-butadiene) is a binder in paper coating, carpet backsizing, wood adhesives, battery electrodes, tire cords, etc. Is widely used.
In the production of butadiene copolymer latex, hydrocarbons may be used in addition to monomers, emulsifiers, polymerization initiators, molecular weight modifiers, and the like.
As a method for producing such a copolymer latex, for example, in JP-A No. 5-112604, in the emulsion polymerization of an aliphatic conjugated diene monomer and another monomer copolymerizable therewith, copolymerization is carried out. A method for polymerizing by adding a non-reactive branched alkane having 5 to 10 carbon atoms is disclosed.
Japanese Patent No. 2961207 discloses a method of emulsion polymerization in the presence of a cyclic unsaturated hydrocarbon having an unsaturated bond in a ring selected from cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, and 1-methylcyclohexene. It is disclosed.
Further, in Japanese Patent No. 2879121, an aliphatic conjugated diene monomer, an ethylenically unsaturated carboxylic acid monomer, and other monomers copolymerizable therewith are chain-like having one unsaturated bond. A process for emulsion polymerization in the presence of an unsaturated hydrocarbon is disclosed.

Japanese Patent Laid-Open No. 5-112604

Japanese Patent No. 2961207

Japanese Patent No. 2879121

In industrializing emulsion polymerization using hydrocarbons as described above, it is necessary to study methods for reducing production costs.
These hydrocarbons are usually volatilized and removed from the copolymer latex together with monomers remaining unreacted as an oily mixture from the copolymer latex by a method such as steam distillation after the completion of emulsion polymerization.
Therefore, in order to reduce the production cost, it is considered to collect the removed hydrocarbon and reuse it for the next emulsion polymerization.
However, when the removed oily mixture is reused as it is, there is a problem that productivity is greatly reduced such that agglomerates are generated and the yield of the copolymer latex is reduced or the inside of the polymerization system is soiled.
The object of the present invention is to emulsion polymerize 1,3-butadiene and other monomers copolymerizable with 1,3-butadiene in the presence of an unsaturated hydrocarbon having one unsaturated bond. To provide a method for producing a copolymer latex capable of obtaining a copolymer latex with less aggregates even when an oily mixture containing an unsaturated hydrocarbon having one unsaturated bond is reused. It is.

The method for producing a copolymer latex of the present invention comprises a monomer composition containing 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene, one unsaturated bond. A method for producing a copolymer latex in which emulsion polymerization is carried out in the presence of an unsaturated hydrocarbon having an unsaturated hydrocarbon obtained by distilling the copolymer latex after polymerization in the previous production of the copolymer latex The oily mixture containing hydrogen is blended in the emulsion polymerization system so that the ratio of 4-vinylcyclohexene to the total amount of the monomer composition, the unused unsaturated hydrocarbon, and the oily mixture is 600 ppm or less. It is characterized by that.
Further, the method for producing a copolymer latex of the present invention comprises a monomer composition containing 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene, having an unsaturated bond. A method for producing a copolymer latex in which emulsion polymerization is carried out in the presence of one unsaturated hydrocarbon, which is obtained by distilling the copolymer latex after polymerization in the previous production of the copolymer latex. This time, the ratio of 4-vinylcyclohexene derived from the oily mixture to the total amount of the monomer composition, the unused unsaturated hydrocarbon and the oily mixture was 600 ppm or less. It is characterized by blending in the emulsion polymerization system.
In the method for producing a copolymer latex of the present invention, it is preferable that the oily mixture is further distilled by being heated to a temperature at which the unsaturated hydrocarbon evaporates.
In the method for producing a copolymer latex of the present invention, it is preferable that the unsaturated hydrocarbon is cyclohexene.

According to the method for producing a copolymer latex of the present invention, it is possible to produce a copolymer latex with few aggregates while reducing the production cost by reusing unsaturated hydrocarbons.
Also, by recycling unsaturated hydrocarbons, the amount of unsaturated hydrocarbons discarded can be greatly reduced, and the environmental burden can be reduced.

In the method for producing a copolymer latex of the present invention, a monomer composition containing 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene is combined with one unsaturated bond. Emulsion polymerization is carried out in the presence of unsaturated hydrocarbons.
The monomer composition contains, for example, 10 to 90% by weight of 1,3-butadiene.
The 1,3-butadiene may contain unreacted 1,3-butadiene recovered by steam distillation described later.
Examples of other monomers copolymerizable with 1,3-butadiene include, for example, alkenyl aromatic monomers, vinyl cyanide monomers, unsaturated carboxylic acid monomers, and unsaturated carboxylic acid alkyl ester monomers. And unsaturated monomers containing a hydroxyalkyl group, unsaturated carboxylic acid amide monomers, and the like.
The other monomer copolymerizable with 1,3-butadiene is blended in the monomer composition at a ratio of, for example, 10 to 90% by weight.

Examples of the alkenyl aromatic monomer include styrene, α-methylstyrene, methyl α-methylstyrene, vinyl toluene, and divinylbenzene.
Of these alkenyl aromatic monomers, styrene is preferable.

Examples of the vinyl cyanide monomer include acrylonitrile, methacrylonitrile, α-chloroacrylonitrile, α-ethylacrylonitrile and the like.
Of these vinyl cyanide monomers, acrylonitrile and methacrylonitrile are preferable.

  Examples of the unsaturated carboxylic acid monomer include monobasic acids such as acrylic acid, methacrylic acid, and crotonic acid, and dibasic acids (or anhydrides thereof) such as maleic acid, fumaric acid, and itaconic acid. It is done.

Examples of unsaturated carboxylic acid alkyl ester monomers include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, glycidyl methacrylate, dimethyl fumarate, diethyl fumarate, Examples thereof include dimethyl maleate, diethyl maleate, dimethyl itaconate, monomethyl fumarate, monoethyl fumarate and the like.
Of these unsaturated carboxylic acid alkyl ester monomers, 2-ethylhexyl acrylate and methyl methacrylate are preferable.

Examples of the unsaturated monomer containing a hydroxyalkyl group include β-hydroxyethyl acrylate, β-hydroxyethyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, 3-chloro-2- Examples include hydroxypropyl methacrylate, di- (ethylene glycol) maleate, di- (ethylene glycol) itaconate, 2-hydroxyethyl maleate, bis (2-hydroxyethyl) maleate, 2-hydroxyethyl methyl fumarate and the like.
Of these unsaturated monomers containing a hydroxyalkyl group, β-hydroxyethyl acrylate is preferable.

Examples of the unsaturated carboxylic acid amide monomer include acrylamide, methacrylamide, N-methylol acrylamide, N-methylol methacrylamide, N, N-dimethylacrylamide and the like.
Of these unsaturated carboxylic acid amide monomers, acrylamide and methacrylamide are preferable.

Further, as other monomers copolymerizable with 1,3-butadiene, for example, monomers used in ordinary emulsion polymerization such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride, etc. Can also be used.
These other monomers copolymerizable with 1,3-butadiene can be used alone (one kind only) or in combination of two or more kinds.

Examples of the unsaturated hydrocarbon having one unsaturated bond include cyclopentene, cyclohexene, cycloheptene, 4-methylcyclohexene, 1-methylcyclohexene, 1-pentene, 2-methyl-1-pentene, 1-hexene, 1-hexene, Examples include heptene, 2,4,4-trimethyl-1-pentene, and 1-octene.
Of these unsaturated hydrocarbons, cyclohexene is preferable.
These unsaturated hydrocarbons can be used alone (one kind only) or in combination of two or more kinds.

Further, these unsaturated hydrocarbons can be recovered from the copolymer latex after the completion of the polymerization in the production of the copolymer latex and reused in the next and subsequent productions.
In order to recover the unsaturated hydrocarbon after completion of the polymerization of the copolymer latex, it is recovered from the copolymer latex together with the remaining unreacted monomers and the like by a method such as distillation.
The method for distilling the copolymer latex is not particularly limited, and a known method can be used. Preferably, steam distillation is performed at 50 to 100 ° C.
Here, the oily mixture removed from the copolymer latex by distillation (hereinafter referred to as “oily mixture”) includes, in addition to unsaturated hydrocarbons, volatile monomers, and the like, during the emulsion polymerization. 4-vinylcyclohexene produced (hereinafter abbreviated as 4VC) is included.
To incorporate this oily mixture in emulsion polymerization of 1,3-butadiene and other monomers copolymerizable with 1,3-butadiene, a monomer composition and unused unsaturated The ratio of 4VC to the total amount of the hydrocarbon (that is, the unsaturated hydrocarbon in the oily mixture) and the oily mixture is, for example, 600 ppm or less, preferably 500 ppm or less, and more preferably 400 ppm or less.
In addition, the oily mixture is 4 VC derived from the oily mixture with respect to the total amount of the monomer composition, the unused unsaturated hydrocarbon (that is, the unsaturated hydrocarbon in the oily mixture is excluded), and the oily mixture. The ratio is, for example, 600 ppm or less, preferably 500 ppm or less, more preferably 400 ppm or less.
When 4VC exceeding 600 ppm is brought into the emulsion polymerization system, the amount of aggregates increases, and the yield of the copolymer latex decreases. Moreover, the tendency for the particle diameter of the obtained copolymer to become large is seen, and the reproducibility of superposition | polymerization deteriorates.
As a method for controlling the amount of 4VC brought into the emulsion polymerization system in the polymerization for reusing the oily mixture, the amount of 4VC in the oily mixture is measured and the amount of 4VC brought into the emulsion polymerization system is calculated. It can be determined whether or not it can be reused as it is.
At this time, the amount of 4VC contained in 1,3-butadiene (which may contain unreacted 1,3-butadiene recovered by steam distillation) used for the polymerization is also measured and brought into the emulsion polymerization system. The 4VC amount is calculated and added to the 4VC amount brought into the emulsion polymerization system from the oily mixture.
In addition, as a method for reducing 4VC brought into the emulsion polymerization system, for example, the oily mixture is further distilled by heating to a temperature at which the unsaturated hydrocarbon evaporates, and the distillate containing the unsaturated hydrocarbon (hereinafter, referred to as “an unsaturated hydrocarbon”). And a method of using an oily mixture and a distillate, for example, a method of using a new unsaturated hydrocarbon in combination with an oily mixture and / or a distillate. As for the distillate, similarly to the oily mixture described above, the amount of 4VC in the distillate is measured, and the amount of 4VC brought into the polymerization system is calculated based on the amount used, and it is determined whether or not it can be reused.
By reusing the oily mixture and / or distillate, the amount of oily mixture containing unsaturated hydrocarbons can be greatly reduced.

  A known method can be applied as the emulsion polymerization method in the present invention. That is, the method for adding the monomer and other components is not particularly limited. In addition, any known method can be employed for the monomer addition method. In emulsion polymerization, known emulsifiers, polymerization initiators, chain transfer agents, electrolytes, chelating agents and the like can be used.

Examples of the emulsifier include sulfate esters of higher alcohols, alkylbenzene sulfonates, alkyl diphenyl ether disulfonates, aliphatic sulfonates, aliphatic carboxylates, dehydroabietic acid salts, formalin condensates of naphthalene sulfonic acid, Anionic surfactants such as sulfate ester salts of ionic surfactants, for example, nonionic surfactants such as alkyl ester type, alkyl phenyl ether type, and alkyl ether type of polyethylene glycol.
These emulsifiers can be used alone (one kind only) or in combination of two or more kinds.

Examples of the polymerization initiator include water-soluble polymerization initiators such as lithium persulfate, potassium persulfate, sodium persulfate, and ammonium persulfate, such as cumene hydroperoxide, benzoyl peroxide, t-butyl hydroperoxide, and acetyl peroxide. Oil-soluble polymerization initiators such as oxide, diisopropylbenzene hydroperoxide, 1,1,3,3-tetramethylbutyl hydroperoxide, for example, redox polymerization initiators can be used as appropriate.
Of these polymerization initiators, potassium persulfate, sodium persulfate, cumene hydroperoxide, and t-butyl hydroperoxide are preferable.

Examples of the chain transfer agent include xanthogen compounds such as alkyl mercaptan, dimethylxanthogen disulfide, and diisopropylxanthogen disulfide, for example, thiuram compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide, and tetramethylthiuram monosulfide. , 6-Di-t-butyl-4-methylphenol, phenolic compounds such as styrenated phenol, for example, allyl compounds such as allyl alcohol, for example, halogenated hydrocarbon compounds such as dichloromethane, dibromomethane, and carbon tetrabromide For example, vinyl ethers such as α-benzyloxystyrene, α-benzyloxyacrylonitrile, α-benzyloxyacrylamide, such as triphenylethane, Data phenylethane, acrolein, methacrolein, thioglycolic acid, thiomalate, 2-ethylhexyl thioglycolate, Tapinoren, such as α- methylstyrene dimer.
These chain transfer agents can be used alone (one kind only) or in combination of two or more kinds.

  The particle diameter of the copolymer latex obtained by the method for producing the copolymer latex of the present invention is not particularly limited, and the average particle diameter by the photon correlation method is, for example, 50 to 300 nm. If the average particle size of the copolymer latex is less than 50 nm, the viscosity of the copolymer latex becomes high and handling may be difficult, which is not preferable. When the average particle diameter of the copolymer latex is larger than 300 nm, the surface area of the copolymer latex is decreased, and the adhesive force may be lowered, which is not preferable. The particle size of the copolymer latex can be adjusted by appropriately changing the various emulsifiers used in the polymerization of the copolymer latex, the type and amount of polymerization initiator used, the addition method, the proportion of polymerization water used, etc. is there.

  The gel content of the copolymer latex in the present invention is not particularly limited, but is, for example, 30 to 100% by weight. If the gel content is less than 30% by weight, the adhesive force tends to decrease, which is not preferable.

  For the polymerization of the copolymer latex of the present invention, known oxygen scavengers, chelating agents, dispersants, antifoaming agents, anti-aging agents, preservatives, antibacterial agents, flame retardants, UV absorbers, etc., as necessary. These additives can also be used. These additives are not particularly limited in both types and amounts used, and can be used in appropriate amounts.

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 according to the following methods.
In this example, 1,3-butadiene containing 80 ppm of 4VC was used as “1,3-butadiene”, and cyclohexene containing no 4VC (less than 1 ppm) was used as “cyclohexene”. 4VC contained in "1,3-butadiene" was quantified based on gas chromatographic measurement.

Gas chromatograph measurement conditions for “1,3-butadiene” Sample volume: 0.5 μL
Detector: FID
Injection temperature: 250 ° C
Detector temperature: 250 ° C
Column: length / inner diameter / film thickness = 50 m / 0.53 mm / 50 μm (GS-ALUMINA 115-3552)
Carrier gas: He 6 mL / min Split ratio: 1/50
Column temperature: After holding at 45 ° C. for 3 minutes, the temperature was raised to 195 ° C. at 6 ° C./min and held at 195 ° C. for 15 minutes.

Measurement of the amount of agglomerates in the copolymer latex After the polymerization was completed and before steam distillation, 1 kg of the copolymer latex was sampled and filtered through a 300-mesh metal mesh made of stainless steel. After drying the agglomerates remaining on the wire mesh, the weight was measured and the ratio to the sample (in terms of solid content) was determined to obtain the agglomerate generation rate. The incidence was evaluated in the following four stages.
: Less than 0.01% (very little)
○: 0.01 to less than 0.02% (less)
Δ: 0.02 to less than 0.05% (slightly more)
×: 0.05% or more (more)

Measurement of 4-vinylcyclohexene in oily mixture and distillate GC-2014 type manufactured by Shimadzu Corporation was used as a gas chromatograph.
(1) Preparation of sample Oily mixtures A to F and distillates A to F of oily mixtures (see the following examples) were used as measurement samples as they were.
(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 was raised to 170 ° C. at 10 ° C./minute, further raised to 230 ° C. at 20 ° C./minute, and held at 230 ° C. for 10 minutes.
(3) Quantification method A calibration curve was prepared using a sample obtained by diluting 4VC with cyclohexene, and 4VC contained in the sample was quantified using the calibration curve.

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

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. Thereafter, this is filtered through a weighed 300-mesh stainless steel wire mesh, and then toluene is evaporated to dryness. After the drying, the mesh weight is subtracted, and the weight of the sample after drying is weighed to obtain Yg. The gel content was calculated from the following formula.
Gel content (%) = Y / X * 100

Example 1
As the first polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 1.5 parts of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, monomers shown in the first stage of Table 1, t-Dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 70 ° C. Subsequently, the monomer shown in the second row of Table 1, t-dodecyl mercaptan, and cyclohexene 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 obtained polymer was adjusted to pH 7 with potassium hydroxide and subjected to steam distillation at 80 ° C. As a result, the obtained polymer was separated into a copolymer latex A1 and an oily mixture A containing cyclohexene. A part of the obtained oily mixture A was distilled at 95 ° C. to obtain a distillate A containing cyclohexene.
The concentration of 4VC in the oily mixture A was 3,502 ppm. Further, the concentration of 4VC in the distillate A was 2,110 ppm.
Thereafter, as the polymerization for reuse 1, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerized water, 1.5 parts of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, and the single stage shown in Table 1 were used. A monomer, t-dodecyl mercaptan, cyclohexene and distillate A were charged, and the temperature was raised to 70 ° C. Next, the monomer, t-dodecyl mercaptan and oily mixture A shown in the second row of Table 1 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 obtained polymer was adjusted to pH 7 with potassium hydroxide and steam distilled at 80 ° C. to obtain a copolymer latex A2.
In addition, as the polymerization for reuse 2, a pressure-resistant polymerization reactor equipped with a stirrer was charged with 150 parts of polymerized water, 1.5 parts of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, and the single stage shown in Table 1. The monomer, t-dodecyl mercaptan and distillate A were charged, and the temperature was raised to 70 ° C. Next, the monomer, t-dodecyl mercaptan and oily mixture A shown in the second row of Table 1 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 obtained polymer was adjusted to pH 7 with potassium hydroxide and steam distilled at 80 ° C. to obtain a copolymer latex A3.

Example 2
As the first polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 0.7 parts of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, monomers shown in the first stage of Table 1, t-Dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 68 ° C. Subsequently, the monomer shown in the second row of Table 1 and t-dodecyl mercaptan were continuously added in 8 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 97%. Next, the obtained polymer was adjusted to pH 7 with potassium hydroxide and subjected to steam distillation at 80 ° C. Thereby, the obtained polymer was separated into a copolymer latex B1 and an oily mixture B containing cyclohexene. A part of the oily mixture B was distilled at 95 ° C. to obtain a distillate B containing cyclohexene.
The concentration of 4VC in the oily mixture B was 13,119 ppm. Further, the concentration of 4VC in the distillate B was 6,074 ppm.
Thereafter, as a reusable polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 0.7 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, and the single amount shown in the first stage of Table 1 Body, t-dodecyl mercaptan, cyclohexene and distillate B were charged and heated to 68 ° C. Subsequently, the monomer shown in the second row of Table 1 and t-dodecyl mercaptan were continuously added in 8 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 97%. Next, the obtained polymer was adjusted to pH 7 with potassium hydroxide and steam distilled at 80 ° C. to obtain a copolymer latex B2.

Example 3
Except having changed into the monomer shown in Table 2, and other compounds, it carried out similarly to Example 1, copolymer latex C1 in the 1st superposition | polymerization, the oil-based mixture C containing cyclohexene, the distillate C containing cyclohexene, A copolymer latex C2 was obtained in the recycling polymerization.
The concentration of 4VC in the oily mixture C was 4,188 ppm. The concentration of 4VC in the distillate C was 1,962 ppm.

Example 4
As the first polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 0.8 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, monomers shown in the first stage of Table 2, t-Dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 70 ° C. Subsequently, the monomer shown in the second row of Table 2, t-dodecyl mercaptan and cyclohexene were continuously added in 7 hours. Subsequently, the monomer shown in the third row of Table 2 and t-dodecyl mercaptan were continuously added in 4 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the obtained polymer was adjusted to pH 7 with sodium hydroxide and subjected to steam distillation at 80 ° C. Thereby, the obtained polymer was separated into a copolymer latex D1 and an oily mixture D containing cyclohexene. The oily mixture D was distilled at 95 ° C. to obtain a distillate D containing cyclohexene.
The concentration of 4VC in the oily mixture D was 7,305 ppm. The concentration of 4VC in the distillate D was 5,162 ppm.
Thereafter, as a polymerization for reuse 1, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerized water, 0.8 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, the first stage shown in Table 2 were used. A monomer, t-dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 70 ° C. Next, the monomer, t-dodecyl mercaptan and oily mixture D shown in the second row of Table 2 were continuously added in 7 hours. Subsequently, the monomer shown in the third row of Table 2 and t-dodecyl mercaptan were continuously added in 4 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the obtained polymer was adjusted to pH 7 with sodium hydroxide and subjected to steam distillation at 80 ° C. to obtain a copolymer latex D2.
Further, as polymerization of reuse 2, in the polymerization of copolymer latex B2 (see Example 2 above), cyclohexene is replaced with oily mixture D and continuously added in the second stage, and distillate B is replaced with distillate D. Otherwise, polymerization and steam distillation were performed in the same manner to obtain a copolymer latex D3.

Comparative Example 1
As the first polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 0.8 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, monomers shown in the first stage of Table 3, t-Dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 68 ° C. Subsequently, the monomer shown in the second row of Table 1 and t-dodecyl mercaptan were continuously added in 8 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the obtained polymer was adjusted to pH 7 with sodium hydroxide and subjected to steam distillation at 80 ° C. Thereby, the obtained polymer was separated into a copolymer latex E1 and an oily mixture E containing cyclohexene.
Distillate E containing cyclohexene was obtained by distilling oily mixture E at 95 ° C.
The concentration of 4VC in the oily mixture E was 9,950 ppm. The concentration of 4VC in the distillate E was 4,135 ppm.
Thereafter, as the polymerization for reuse 1, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerized water, 0.8 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, the first stage shown in Table 3 were used. The monomer, t-dodecyl mercaptan, cyclohexene and oily mixture E were charged, and the temperature was raised to 68 ° C. Subsequently, the monomer shown in the second row of Table 1 and t-dodecyl mercaptan were continuously added in 8 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the obtained polymer was adjusted to pH 7 with sodium hydroxide and steam distilled at 80 ° C. to obtain a copolymer latex E2.
In addition, as the polymerization of reuse 2, in the polymerization of the copolymer latex A3 (see Example 1 above), the oily mixture E was used instead of the oily mixture A, and the distillate E was used instead of the distillate A. In the same manner, polymerization and steam distillation were performed to obtain a copolymer latex E3.

Comparative Example 2
As the first polymerization, in a pressure-resistant polymerization reactor equipped with a stirrer, 150 parts of polymerization water, 0.9 part of sodium dodecylbenzenesulfonate, 1 part of potassium persulfate, monomers shown in the first stage of Table 3, t-Dodecyl mercaptan and cyclohexene were charged, and the temperature was raised to 70 ° C. Subsequently, the monomer shown in the second row of Table 3 and t-dodecyl mercaptan were continuously added in 8 hours. Further, the polymerization was continued, and the polymerization was terminated when the polymerization conversion rate exceeded 98%. Next, the obtained polymer was adjusted to pH 7 with sodium hydroxide and subjected to steam distillation at 80 ° C. Thereby, the obtained polymer was separated into a copolymer latex F1 and an oily mixture F containing cyclohexene.
Distillate F containing cyclohexene was obtained by distilling oily mixture F at 95 ° C.
The concentration of 4VC in the oily mixture F was 14,473 ppm. The concentration of 4VC in the distillate F was 6,208 ppm.
Thereafter, as the polymerization of reuse 1, except that cyclohexene was changed to the oily mixture F in the polymerization of the copolymer latex F1, polymerization and steam distillation were performed in the same manner to obtain a copolymer latex F2.
Further, as the polymerization of reuse 2, except that cyclohexene was changed to the distillate F in the polymerization of the copolymer latex F1, polymerization and steam distillation were performed in the same manner to obtain a copolymer latex F3.

From the results of Tables 1 and 2, in the examples of the present invention, even when cyclohexene is reused as an oily mixture containing cyclohexene or as a distillate of an oily mixture, the rate of occurrence of aggregates is small. The particle size of the resulting copolymer latex was also almost the same as the first polymerization. It is clear that the productivity is good and the polymerization reproducibility is also good.

  From the results of Table 3, in both Comparative Examples 1 and 2, the amount of 4VC brought into the polymerization system exceeds the upper limit of the present invention, the generation rate of aggregates is very large, and the productivity is inferior. I understand that. In addition, the particle size of the copolymer latex obtained by reusing cyclohexene tends to be larger than that of the copolymer latex obtained at the first time, and it is clear that the reproducibility of polymerization is also inferior. It is.

As described above, the method for producing the copolymer latex of the present invention includes 1,3-butadiene and other monomers copolymerizable with 1,3-butadiene, unsaturated carbonized carbon having one unsaturated bond. When producing a copolymer latex that undergoes emulsion polymerization in the presence of hydrogen, the unsaturated hydrocarbon having one unsaturated bond may be reused as an oily mixture itself or as a distillate. Less copolymer latex is obtained. From this, the amount of discarding the oily mixture can be greatly reduced, and the environmental load and the manufacturing cost can be greatly reduced. Further, the obtained copolymer latex has few aggregates like the conventional copolymer latex, so it is used for paper coating, carpet backsizing, wood-based adhesives, battery electrodes, and tire cord fields. It can be suitably used as a binder in the above.
Although the above description has been provided as an exemplary embodiment of the present invention, this is merely an example and should not be construed as limiting. Modifications of the present invention apparent to those skilled in the art are intended to be included within the scope of the following claims.

Claims (6)

Emulsion polymerization of a monomer composition containing 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene in the presence of an unsaturated hydrocarbon having one unsaturated bond A method for producing a copolymer latex, wherein the oily mixture containing the unsaturated hydrocarbon obtained by distilling the copolymer latex after polymerization in the production of the previous copolymer latex, It is characterized in that it is blended in this emulsion polymerization system so that the ratio of 4-vinylcyclohexene to the total amount of the monomer composition, the unused unsaturated hydrocarbon and the oily mixture is 600 ppm or less, A method for producing a copolymer latex. The method for producing a copolymer latex according to claim 1, wherein the oily mixture is further distilled by being heated to a temperature at which the unsaturated hydrocarbon evaporates. The method for producing a copolymer latex according to claim 1, wherein the unsaturated hydrocarbon is cyclohexene. Emulsion polymerization of a monomer composition containing 1,3-butadiene and another monomer copolymerizable with 1,3-butadiene in the presence of an unsaturated hydrocarbon having one unsaturated bond A method for producing a copolymer latex, wherein the unsaturated mixture containing the unsaturated hydrocarbon obtained by distilling the copolymer latex after polymerization in the previous production of the copolymer latex, It mix | blends in this emulsion polymerization system so that the ratio of 4-vinylcyclohexene derived from the said oily mixture with respect to the total amount of a body composition, the unused said unsaturated hydrocarbon, and the said oily mixture may be 600 ppm or less. A method for producing a copolymer latex. The method for producing a copolymer latex according to claim 4, wherein the oily mixture is further distilled by being heated to a temperature at which the unsaturated hydrocarbon evaporates. The method for producing a copolymer latex according to claim 4, wherein the unsaturated hydrocarbon is cyclohexene.