JP2014169403A - Method for producing copolymer latex, and copolymer latex - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for producing copolymer latex that can lower the production cost by recycling the oily mixture comprising unsaturated hydrocarbons when emulsion polymerizing 1,3-butadiene, styrene, and other monomers co-polymerizable therewith.SOLUTION: The method for producing copolymer latex includes emulsion polymerizing a monomer composition comprising 1,3-butadiene, styrene, and other monomers co-polymerizable therewith by feeding the oily mixture comprising unsaturated hydrocarbons obtained by distilling the copolymer latex finished with polymerization in the previous copolymer latex production, into the present emulsion polymerization system such that the proportion of 4-phenyl cyclohexene coming from the oily mixture to the total amount of the monomer composition and the oily mixture comprising unused unsaturated hydrocarbons is 20 ppm or less.

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 used as a binder in paper coating, carpet backsizing, wood adhesives, battery electrodes, tire cords, etc. 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.

  Then, the objective of this invention is providing the manufacturing method of copolymer latex which can reduce manufacturing cost.

  The method for producing a copolymer latex of the present invention comprises a monomer composition containing 1,3-butadiene, styrene, 1,3-butadiene and another monomer copolymerizable with styrene. A method for producing a copolymer latex in which emulsion polymerization is carried out in the presence of an unsaturated hydrocarbon having one saturated bond, obtained by distilling the copolymer latex after polymerization in the production of a previous copolymer latex. The ratio of 4-phenylcyclohexene derived from the oily mixture to the total amount of the monomer composition, the unused unsaturated hydrocarbon, and the oily mixture is determined as follows. It is characterized by blending in the emulsion polymerization system this time so that it becomes 20 ppm or less.

  The method for producing a copolymer latex of the present invention comprises a monomer composition containing 1,3-butadiene, styrene, and 1,3-butadiene and another monomer copolymerizable with styrene. A method for producing a copolymer latex in which emulsion polymerization is carried out in the presence of an unsaturated hydrocarbon having one unsaturated bond, wherein the post-polymerization copolymer latex is distilled in the previous production of the copolymer latex. The ratio of 4-phenylcyclohexene to the total amount of the monomer composition, the unused unsaturated hydrocarbon, and the oily mixture is 20 ppm or less. In addition, it is characterized by being blended in the emulsion polymerization system of this time.

  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.

  The copolymer latex of the present invention is characterized by being produced by the above-described method for producing a copolymer latex.

  According to the method for producing a copolymer latex of the present invention, the production cost can be reduced by reusing unsaturated hydrocarbons as compared with the case of using all new unsaturated hydrocarbons.

  Moreover, according to the method for producing a copolymer latex of the present invention, the amount of unsaturated hydrocarbons to be 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, styrene, and 1,3-butadiene and another monomer copolymerizable with styrene is used. Emulsion polymerization is performed in the presence of an unsaturated hydrocarbon having one saturated bond.

  1,3-butadiene is blended in the monomer composition in a proportion of, for example, 10% by mass or more, preferably 15% by mass or more, for example, 90% by mass or less, preferably 85% by mass or less. .

  The 1,3-butadiene may contain unreacted 1,3-butadiene recovered by distillation described later.

  Styrene is blended in the monomer composition in a proportion of, for example, 10% by mass or more, preferably 15% by mass or more, for example, 90% by mass or less, preferably 85% by mass or less.

  The styrene may contain unreacted styrene recovered by distillation described later.

  If the blending ratio of styrene is not more than the above lower limit value, the resulting copolymer latex dry film may become sticky during heating.

  Examples of other monomers copolymerizable with 1,3-butadiene and styrene (hereinafter referred to as other monomers) include alkenyl aromatic monomers other than styrene, vinyl cyanide monomer , Unsaturated carboxylic acid monomer, unsaturated carboxylic acid alkyl ester monomer, unsaturated monomer containing a hydroxyalkyl group, unsaturated carboxylic acid amide monomer, and the like.

  The other monomer is blended in the monomer composition in a proportion of, for example, 5% by mass or more, preferably 10% by mass or more, for example, 75% by mass or less, preferably 70% by mass or less. Is done.

  Examples of the alkenyl aromatic monomer include α-methylstyrene, methyl α-methylstyrene, vinyl toluene, and divinylbenzene.

  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.

  Furthermore, as other monomers, for example, monomers used in usual emulsion polymerization such as ethylene, propylene, vinyl acetate, vinyl propionate, vinyl chloride, vinylidene chloride can be used.

  These other monomers can be used alone (one type only) or in combination of two or more types. Of these other monomers, an unsaturated carboxylic acid monomer and an unsaturated carboxylic acid alkyl ester monomer are preferable.

  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 the oily mixture) is subjected to emulsion polymerization in addition to unsaturated hydrocarbons and volatile monomers. By-product 4-phenylcyclohexene (hereinafter abbreviated as 4PC) is included.

  In order to blend this oily mixture in the emulsion polymerization of 1,3-butadiene, styrene, and other monomers, the monomer composition and unused unsaturated hydrocarbons (ie, 4PC derived from the oily mixture relative to the total amount of the unsaturated hydrocarbon (new unsaturated hydrocarbon) blended in the emulsion polymerization (excluding the unsaturated hydrocarbon in the oily mixture) and the oily mixture For example, the proportion is blended so as to be 20 ppm or less, preferably 10 ppm or less, and more preferably 5 ppm or less.

  When 4PC exceeding the upper limit 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. Moreover, the dried film of the obtained copolymer latex may become sticky when heated.

  As a method for controlling the amount of 4PC brought into the emulsion polymerization system in the polymerization for reusing the oily mixture, the amount of 4PC in the oily mixture is measured and the amount of 4PC 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 4PC contained in the unreacted 1,3-butadiene recovered by distillation and unreacted styrene recovered by distillation is also measured, and the amount of 4PC brought into the emulsion polymerization system is measured. Calculate and add to the amount of 4PC brought from the oily mixture into the emulsion polymerization system.

  In addition, as a method for reducing 4PC 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 a distillate containing the unsaturated hydrocarbon (hereinafter, referred to as “an unsaturated hydrocarbon”). A method of using an oily mixture and a distillate, for example, a method of using a new unsaturated hydrocarbon in combination with at least one of an oily mixture and a distillate, etc. Can be mentioned. As for the distillate, similarly to the oily mixture described above, the amount of 4PC in the distillate is measured, the amount of 4PC brought into the polymerization system is calculated based on the amount used, and it is judged whether or not it can be reused.

  By reusing at least one of the oily mixture and the distillate, the amount of waste of the 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 alkyl mercaptans such as xanthogen compounds such as dimethylxanthogen disulfide and diisopropylxanthogen disulfide, for example, thiuram compounds such as tetramethylthiuram disulfide, tetraethylthiuram disulfide and tetramethylthiuram monosulfide, for example. 2,6-di-t-butyl-4-methylphenol, styrenated phenol and other phenolic compounds, for example, allyl compounds such as allyl alcohol, for example, halogenated carbonization such as dichloromethane, dibromomethane, carbon tetrabromide, etc. Hydrogen compounds such as α-benzyloxystyrene, α-benzyloxyacrylonitrile, vinyl ethers such as α-benzyloxyacrylamide, such as triphenyl ether Emissions, pentaphenylethane, 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 nm or more, preferably 70 nm or more, for example, 300 nm. Hereinafter, it is preferably 270 nm or less. If the average particle diameter of the copolymer latex is less than the above lower limit, 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 the above upper limit, the surface area of the copolymer latex is decreased, and the adhesive force may be decreased, 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% by mass or more, preferably 40% by mass or more, for example, 99% by mass or less, preferably 95% by mass or less. If the gel content is less than the above lower limit, the adhesive force tends to decrease, which is not preferable. The gel content is measured, for example, by the method of Examples described later.

  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. In the examples, parts and% indicating the mixing ratio are based on mass. Moreover, numerical values, such as a mixture ratio in an Example, can be substituted for the upper limit value or the lower limit value of the corresponding portion described in the above embodiment.

In this example, 1,3-butadiene and styrene were used that did not contain 4PC (less than 1 ppm).
<Examples and Comparative Examples>
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, an oily mixture containing cyclohexene was separated from the obtained polymer to obtain a copolymer latex. Thereafter, a part of the separated oily mixture was distilled at 95 ° C. to obtain a distillate containing cyclohexene.

  The concentration of 4PC in the oily mixture and the concentration of 4PC in the distillate were measured by the following measuring method. Moreover, the average particle diameter and gel content of copolymer latex were measured by the following measuring method. The results are shown in Table 1.

  Thereafter, a copolymer latex was obtained in the same manner as in the first polymerization, except that the monomers, t-dodecyl mercaptan, cyclohexene, oily mixture and distillate shown in Table 1 were used as the polymerization for reuse.

  The average particle diameter and gel content of the obtained copolymer latex were measured by the following measuring method. The results are shown in Table 1.

Examples 2-5 and Comparative Examples 1-3
Polymerization was carried out in the same manner as in Example 1 except that the amount of monomer, t-dodecyl mercaptan and cyclohexene was changed to the amounts shown in Table 1 as the first polymerization, and the resulting polymer was treated with potassium hydroxide. Was used to adjust the pH to 7, and steam distillation at 80 ° C. was performed to separate the oily mixture containing cyclohexene from the polymer to obtain a copolymer latex. A part of the separated oily mixture was distilled at 95 ° C. to obtain a distillate containing cyclohexene.

  The concentration of 4PC in the oily mixture and the concentration of 4PC in the distillate were measured by the following measuring method. Moreover, the average particle diameter and gel content of copolymer latex were measured by the following measuring method. The results are shown in Tables 1 and 2.

  Thereafter, a copolymer latex was obtained in the same manner as in the first polymerization, except that the monomer, t-dodecyl mercaptan, cyclohexane, oily mixture and distillate shown in Table 1 were charged as the polymerization for reuse.

The average particle size and gel content of the copolymer latex were measured by the following measuring methods. The results are shown in Tables 1 and 2.
<Evaluation methods for various physical properties>
1. Method for measuring 4PC content ratio of oily mixture or distillate As a gas chromatograph, GC-2014 type manufactured by Shimadzu Corporation was used.
(1) Preparation of sample The oily mixture or distillate of each Example and each comparative example was made into the measurement sample as it was.
(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) Quantitative method The retention time was confirmed using the sample which diluted phenylcyclohexene with the dimethylformamide, and this was assumed to be the retention time of 4PC. The sample was measured, and 4PC was quantified by the peak area appearing at the retention time of 4PC.

  In addition, when measuring the 4PC content ratio of unreacted styrene recovered by distillation, similarly, the recovered styrene was directly used as a measurement sample, and was quantified according to the above measurement conditions and determination method.

The method for measuring the 4PC content ratio of unreacted 1,3-butadiene recovered by distillation is the same quantification method as described above using the recovered 1,3-butadiene as it is as a measurement sample under the following gas chromatographic measurement conditions. Quantified according to
<Gas chromatographic 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.
2. Method for Measuring Average Particle Diameter of Copolymer Latex The average particle diameter of the copolymer latex was measured as the average particle diameter by a photon correlation method by a dynamic light scattering method. In the measurement, FPAR-1000 (manufactured by Otsuka Electronics) was used.
3. Method for Measuring Gel Content of Copolymer Latex Copolymer latex is dried at 80 ° C. to produce a latex film. 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
4). Method for evaluating stickiness of copolymer latex Copolymer latex of each example and each comparative example was applied to a polyester film at a coating amount of 12 g / m 2 after drying, and dried in an oven at 120 ° C. for 1 minute to obtain a latex film. Got. The obtained latex film was cut into a 1 cm wide strip and pasted on a black mount.

  The filter paper was placed on the latex film on the black mount, and passed through a hot roll heated to 110 ° C. using a laboratory calender, and the latex film and the filter paper were pressure bonded.

  Thereafter, the filter paper was peeled off from the latex film, and the stickiness of the latex film was visually evaluated from the amount of the filter paper fibers adhering to the latex film surface. The evaluation criteria are shown below.

(Evaluation criteria)
(Double-circle): The fiber of filter paper has not adhered to the latex film.

    ○: The filter paper fibers are slightly adhered to the latex film.

    (Triangle | delta): The fiber of the filter paper has adhered to the area of about 1/3 of a latex film.

    X: A large amount of filter paper fibers adhere to the entire latex film.

Claims (5)

Presence of unsaturated hydrocarbon having one unsaturated bond, a monomer composition comprising 1,3-butadiene, styrene, and 1,3-butadiene and other monomers copolymerizable with styrene A method for producing a copolymer latex that undergoes emulsion polymerization under
An oily mixture containing the unsaturated hydrocarbon obtained by distilling the copolymer latex after polymerization in the production of the copolymer latex is used as the monomer composition and the unused unsaturated hydrocarbon. And the oily mixture to be blended in the emulsion polymerization system so that the proportion of 4-phenylcyclohexene derived from the oily mixture is 20 ppm or less. Method. Presence of unsaturated hydrocarbon having one unsaturated bond, a monomer composition comprising 1,3-butadiene, styrene, and 1,3-butadiene and other monomers copolymerizable with styrene A method for producing a copolymer latex that undergoes emulsion polymerization under
An oily mixture containing the unsaturated hydrocarbon obtained by distilling the copolymer latex after polymerization in the production of the copolymer latex is used as the monomer composition and the unused unsaturated hydrocarbon. The method for producing a copolymer latex is characterized in that it is blended in the current emulsion polymerization system such that the ratio of 4-phenylcyclohexene to the total amount of the oily mixture is 20 ppm or less.   The method for producing a copolymer latex according to claim 1 or 2, 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 any one of claims 1 to 3, wherein the unsaturated hydrocarbon is cyclohexene.   A copolymer latex produced by the method for producing a copolymer latex according to any one of claims 1 to 4.