JP6394075B2 - Method for producing graft copolymer - Google Patents

Description

The present invention relates to the production how the graft copolymer.

  Conventionally, polymer grafting has been performed for the purpose of developing new functional materials. One method for obtaining such a graft copolymer is to use a general radical initiator such as an organic peroxide or an azo compound, and a conjugate such as cis-butadiene rubber or 1,2-vinyl-polybutadiene. A method of free radical grafting the main chain of a diene polymer with a polar monomer is known.

  In recent years, it has been proposed to improve physical properties of rubber compounds such as processability and wear resistance by modifying a conjugated diene polymer using a compound having a stable nitroxide free radical (for example, Patent Document 1 and Patent Document 2). In Patent Document 1, an organic group derived from a compound having a stable nitroxide free radical is introduced into the main chain of the conjugated diene polymer by reacting a compound having a stable nitroxide free radical with a conjugated diene polymer. It is disclosed that this improves the adhesion and processability of the rubber compound. Patent Document 2 discloses that a conjugated diene polymer graft-modified with polyacrylamide is obtained using radical polymerization (NMP) via nitroxide. Patent Document 2 describes that a silica-containing rubber composition obtained by blending the obtained modified conjugated diene polymer and silica exhibits low hysteresis loss and low heat build-up.

JP 2004-182926 A JP 2011-184511 A

  In the conventional method of grafting a polymer by free radical graft polymerization using a general radical initiator, there is a problem that reaction control is difficult and the product is easily gelled. In addition, when NMP is used, there is a problem that it is difficult to control the polymerization of methacrylates.

  The present invention has been made in view of the above problems, and an object of the present invention is to provide a method for producing a graft copolymer that can inhibit the gelation of the product and that can produce a highly stable graft copolymer. To do.

  The present inventors diligently studied to solve the problems of the prior art as described above, and focused on reversible addition-fragmentation chain transfer (RAFT) polymerization. This RAFT polymerization is a polymerization technique that exhibits characteristics related to precision radical polymerization (CRP), similar to NMP, and is characterized by the use of a reversible addition-fragmentation chain transfer agent (RAFT agent). The main feature of CRP is that the polymer chains continue to grow while providing monomers and reaction conditions that support the polymerization, and polymers prepared by RAFT polymerization have the desired molecular structure and molecular weight, as well as a narrow molecular weight. It is supposed to show the distribution. The present inventors applied RAFT polymerization to produce a graft copolymer having a polymer having a double bond in the side chain as a main chain. The knowledge that the gelation of the product can be suppressed was obtained, and the present invention was completed. Specifically, the present invention provides the following graft copolymer production method, polymer composition, pressure-sensitive adhesive and polymer.

[1] A method for producing a graft copolymer obtained by grafting a polymer (D) having a double bond in a side chain with a monomer (B) having a radical polymerizable unsaturated bond, A method for producing a graft copolymer, comprising a polymerization step of polymerizing the monomer (B) in the presence of a carbonylthio compound (A).
[2] A polymer composition comprising a graft polymer obtained by the production method of [1] above.
[3] A pressure-sensitive adhesive containing a graft polymer obtained by the production method according to the above [1].
[4] A polymer which is a graft copolymer obtained by the production method of the above [1] and has a gel content of 1% by mass or less.

  According to the production method of the present invention, when a polymer having a double bond in a side chain is grafted, gelation of the reaction product can be suppressed, and a highly stable graft copolymer can be obtained.

  Hereinafter, the manufacturing method of the graft copolymer of this invention is demonstrated. The present production method relates to a method for producing a graft copolymer obtained by grafting a main chain of a polymer (D) having a double bond in a side chain with a monomer (B), and a thiocarbonylthio compound A polymerization step of polymerizing the monomer (B) in the presence of (A).

<Polymer (D) having double bond in side chain>
As the polymer (D) having a double bond in the side chain (hereinafter also simply referred to as “polymer (D)”), it is preferable to use a vulcanizable rubber. Specific examples thereof include natural rubber (NR), isoprene rubber (IR), butadiene rubber (BR), styrene-butadiene rubber (SBR), acrylonitrile-butadiene rubber (NBR), butyl rubber (IIR), and acrylonitrile-chloroprene rubber. Diene rubbers such as acrylonitrile-isoprene rubber, styrene-chloroprene rubber, styrene-isoprene rubber; ethylene-propylene rubber, ethylene-butene rubber, ethylene-vinyl acetate copolymer (EVA), ethylene-propylene-diene rubber (EPDM), etc. And ethylene-α-olefin copolymer rubber. Of these, a polymer having a structural unit derived from butadiene can be preferably used as the polymer (D). In addition, a polymer (D) can be used individually by 1 type or in combination of multiple types.

  As the polymer (D), a synthetic product or a commercially available product may be used. Examples of commercially available products include, but are not limited to, butadiene-based polymers such as RB810 manufactured by JSR; and styrene-butadiene-based copolymers such as TR2000 manufactured by JSR. When synthesizing the polymer (D), the synthesis method is not particularly limited, and the polymer (D) can be obtained according to a conventionally known organic chemistry method.

As the polymer (D), a copolymer having a high 1,2-vinyl structure can be preferably used, and among them, a high 1,2-vinyl polybutadiene elastomer (BR) having a structural unit derived from butadiene. ) Can be preferably used. If the 1,2-vinyl content of the polymer (D) is too small, the amount of graft chains introduced will be small, making it difficult to obtain the desired properties. From such a viewpoint, the 1,2-vinyl content of the polymer (D) is preferably 5% by mass or more, more preferably 10% by mass or more, and further preferably 25% by mass or more. The vinyl content is a value measured by ¹ H-NMR.

The weight average molecular weight (Mw) in terms of polystyrene by gel permeation chromatography (GPC) of the polymer (D) may be appropriately selected according to the use of the graft copolymer as the final product, but preferably It is 1.0 * 10 < ³ > -2.0 * 10 < ⁶ >, More preferably, it is 1.0 * 10 < ³ > -1.0 * 10 < ⁵ >.

<Monomer (B)>
The monomer (B) is not particularly limited as long as it is a compound having a radical polymerizable unsaturated bond, and can be appropriately selected according to the purpose. The monomer (B) used for polymerization may have a polar group. Examples of the polar group that the monomer (B) may have include a hydroxyl group, an alkoxy group having 1 to 10 carbon atoms, a carbonyloxy group, an alkoxycarbonyl group, an aryloxycarbonyl group, a cyano group, an amide group, and an imide. Group, organosiloxy group, organosilyl group, alkoxysilyl group, amino group, acyl group, sulfonyl group, carboxyl group and the like.

Specific examples of the monomer (B) include, for example, ethylene, propylene, 1,3-butadiene, isoprene, 1,3-pentadiene, styrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2 Non-polar monomers such as 1,4-dimethylstyrene and α-methylstyrene;
(Meth) methyl acrylate, (meth) ethyl acrylate, (meth) acrylate-n-propyl, (meth) acrylate isopropyl, (meth) acrylate allyl, (meth) acrylate-n-butyl, (meth ) -Isobutyl acrylate, t-butyl (meth) acrylate, cyclohexyl (meth) acrylate, phenyl (meth) acrylate, benzyl (meth) acrylate, 2-phenylethyl (meth) acrylate, (meth) 2-ethylhexyl acrylate, isobornyl (meth) acrylate, lauryl (meth) acrylate, glycidyl (meth) acrylate, trimethoxysilylpropyl (meth) acrylate, methoxyethyl (meth) acrylate, (meth) acrylic acid -N, N-dimethylaminoethyl, (meth) acrylic acid-N, N-diethyl Minoethyl, methoxypolyethylene glycol (meth) acrylate, octoxypolyethylene glycol (meth) acrylate, methyl α-methoxyacrylate, methyl α-ethoxyacrylate, 3-methoxyacrylate, methyl crotonate, ethyl crotonate, Α, β-unsaturated carboxylic acid ester compounds such as dialkyl fumarate and itaconic acid;

  Α, β-unsaturated carboxylic acid amide compounds such as N-isopropyl (meth) acrylamide, Nt-butyl (meth) acrylamide, N, N-dimethyl (meth) acrylamide, N, N-diethyl (meth) acrylamide and the like ; Α, β-unsaturated carbonyl compounds such as methyl vinyl ketone, ethyl vinyl ketone, methyl isopropenyl ketone and ethyl isopropenyl ketone; vinyl carboxylates such as vinyl acetate, vinyl butyrate and vinyl benzoate; maleic anhydride, anhydrous Cyclic vinyl compounds such as itaconic acid, N-butylmaleimide and N-phenylmaleimide; N-vinyl compounds such as N-vinylpyrrolidone, vinylcarbazole and vinylimidazole; ethylene glycol di (meth) acrylate, trimethylolpropane tri (meta Acrylate etc. It can be mentioned (meth) acrylonitrile; - carbon compound having two or more carbon double bonds. In addition, a monomer (B) can be used individually by 1 type or in combination of 2 or more types. (Meth) acryl in this specification indicates acrylic and methacrylic.

<Radical generator (C)>
In the present invention, the monomer (B) can be polymerized simply by heating, but it is preferably polymerized in the presence of the radical generator (C) from the viewpoint of productivity. The radical generator (C) can be appropriately selected from radical polymerization initiators generally used in conventionally known radical polymerization. Specific examples include compounds that generate radicals by heating, such as peroxides, azo compounds, and redox initiators, and compounds that generate radicals by irradiation with radiation.

Specific examples of compounds that generate radicals upon heating include peroxides such as t-butyl hydroperoxide, cumene hydroperoxide, t-butyl peroxyacetate, t-butyl peroxybenzoate, t-butyl peroxyoctanoate, peroxy T-butyl neodecanoate, t-butyl peroxyisobutyrate, lauroyl peroxide, t-amyl peroxypivalate, t-butyl peroxypivalate, dicumyl peroxide, benzoyl peroxide, potassium persulfate, ammonium persulfate and the like;
Examples of the azo compound include azobisisobutyronitrile (AIBN), 2,2′-azobis (isobutyronitrile), 2,2′-azobis (2-butanenitrile), 4,4′-azobis (4- Pentanoic acid), 1,1′-azobis (cyclohexanecarbonitrile), 2- (t-butylazo) -2-cyanopropane, 2,2′-azobis [2-methyl-N- (1,1) -bis ( Hydroxymethyl) -2-hydroxyethyl] propionamide, 2,2′-azobis (2-methyl-N-hydroxyethyl) propionamide, 2,2′-azobis (N, N′-dimethyleneisobutylamidine) dichloride, 2,2′-azobis (2-amidinopropane) dichloride, 2,2′-azobis (N, N-dimethyleneisobutyramide), 2,2′-azobis (2-methyl) -N- [1,1-bis (hydroxymethyl) -2-hydroxyethyl] propionamide), 2,2'-azobis (2-methyl-N- [1,1-bis (hydroxymethyl) ethyl] propionamide) ), 2,2′-azobis [2-methyl-N- (2-hydroxyethyl) propionamide], 2,2′-azobis (isobutyramide) dihydrate and the like;

  As a redox initiator, for example, a combination of sulfite, acidic sodium sulfite and ferrous sulfate, a combination of t-butyl hydroperoxide, acidic sodium sulfite and ferrous sulfate, p-menthane hydroperoxide And a combination of ferrous sulfate, sodium ethylenediaminetetraacetate and sodium formaldehyde sulfoxylate; As the compound that generates radicals upon heating, an azo compound is preferable in that a side reaction product due to oxygen or the like is not easily generated, and azobisisobutyronitrile is particularly preferable.

  Specific examples of compounds that generate radicals upon irradiation with radiation include, for example, acetophenone, acetophenone benzyl ketal, 1-hydroxycyclohexyl phenyl ketone, 2,2-dimethoxy-1,2-diphenylethane-1-one, xanthone, fluorenone, Benzaldehyde, fluorene, anthraquinone, triphenylamine, carbazole, 3-methylacetophenone, 4-chlorobenzophenone, 4,4′-dimethoxybenzophenone, 4,4′-diaminobenzophenone, benzoinpropyl ether, benzoin ethyl ether, benzyldimethyl ketal, 1- (4-Isopropylphenyl) -2-hydroxy-2-methylpropan-1-one, 2-hydroxy-2-methyl-1-phenylpropan-1-one, thio Sandone, diethylthioxanthone, 2-isopropylthioxanthone, 2-chlorothioxanthone, 2-methyl-1- [4- (methylthio) phenyl] -2-morpholino-propan-1-one, 2-benzyl-2-dimethylamino-1 -(4-morpholinophenyl) -butanone-1,4- (2-hydroxyethoxy) phenyl- (2-hydroxy-2-propyl) ketone, 2,4,6-trimethylbenzoyldiphenylphosphine oxide, bis- (2, 6-dimethoxybenzoyl) -2,4,4-trimethylpentylphosphine oxide, oligo (2-hydroxy-2-methyl-1- (4- (1-methylvinyl) phenyl) propanone) and the like. In addition, a radical generator (C) can be used individually by 1 type in these or in combination of 2 or more types.

（式（ｓ−１）〜式（ｓ−５）中、Ｚ^１〜Ｚ^１１はそれぞれ独立に１価の有機基である。） <Thiocarbonylthio compound (A)>
As a thiocarbonylthio compound (A), it can select from the chain transfer agent (RAFT agent) used in RAFT polymerization suitably, and can use it. Examples of the thiocarbonylthio compound (A) include a bis (thiocarbonyl) disulfide compound (a compound represented by the following formula (s-1)) and a dithioester compound (a compound represented by the following formula (s-2)). ), A trithiocarbonate compound (a compound represented by the following formula (s-3)), a dithiocarbamate compound (a compound represented by the following formula (s-4)), a xanthate compound (the following formula (s-5) ) And the like.

(In formula (s-1) to formula (s-5), Z ^{1 to} Z ¹¹ are each independently a monovalent organic group.)

The monovalent organic group in Z ^{1 to} Z ¹¹ in the above formulas (s-1) to (s-5) is, for example, an alkyl group having 1 to 30 carbon atoms, a cycloalkyl group, an aryl group, an aralkyl group, an alkylthio group. Group, heterocyclyl group, —NR ¹ R ² , —NR ¹ —NR ² R ³ , —COOR ¹ , —OCOR ¹ , —CONR ¹ R ² , —P (═O) (OR ¹ ) ₂ or —O—P (═O) R ¹ R ² (wherein R ¹ , R ² and R ³ are each independently an alkyl group, a cycloalkyl group, an aryl group or an aralkyl group), and the like. One or more of the hydrogen atoms to be bonded may be substituted with a cyano group, a carboxyl group or the like.
Z ⁴ in the above formula (s-2) and Z ⁸ in the above formula (s-4) are preferably aromatic groups such as a phenyl group, and Z ⁶ in the above formula (s-3), Z ⁹ in the formula (s-4) and Z ¹¹ in the formula (s-5) are preferably alkyl groups.

  Specific examples of the thiocarbonylthio compound (A) include bis (thiocarbonyl) disulfide compounds such as tetraethylthiuram disulfide, tetramethylthiuram disulfide, bis (n-octylmercapto-thiocarbonyl) disulfide, bis (n-dodecylmercapto). -Thiocarbonyl) disulfide, bis (benzylmercapto-thiocarbonyl) disulfide, bis (n-butylmercapto-thiocarbonyl) disulfide, bis (t-butylmercapto-thiocarbonyl) disulfide, bis (n-heptylmercapto-thiocarbonyl) Disulfide, bis (n-hexylmercapto-thiocarbonyl) disulfide, bis (n-pentylmercapto-thiocarbonyl) disulfide, bis (n-nonylmercap) -Thiocarbonyl) disulfide, bis (n-decylmercapto-thiocarbonyl) disulfide, bis (t-dodecylmercapto-thiocarbonyl) disulfide, bis (n-tetradecylmercapto-thiocarbonyl) disulfide, bis (n-hexadecylmercapto) -Thiocarbonyl) disulfide, bis (n-octadecylmercapto-thiocarbonyl) disulfide and the like;

Examples of dithioester compounds include 2-phenyl-2-propylbenzothioate, 4-cyano-4- (phenylthiocarbonylthio) pentanoic acid, 2-cyano-2-propylbenzodithioate and the like;
Examples of trithiocarbonate compounds include S- (2-cyano-2-propyl) -S-dodecyltrithiocarbonate, 4-cyano-4-[(dodecylsulfanyl-thiocarbonyl) sulfanyl] pentanoic acid, cyanomethyldodecyltri Thio-carbonate, 2- (dodecylthiocarbonothiolthio) -2-methylpropionic acid, etc .;
Examples of dithiocarbamate compounds include cyanomethylmethyl (phenyl) carbamodithioate, cyanomethyldiphenylcarbamo-dithioate and the like;
Examples of the xanthate compound include xanthate ester and the like;

  The thiocarbonylthio compound (A) can be appropriately selected from the above depending on the type of the monomer (B) used in the graft reaction. For example, when a (meth) acrylic monomer is used as the monomer (B), at least one selected from the group consisting of bis (thiocarbonyl) disulfide compounds, dithiobenzoate compounds and trithiocarbonate compounds is preferably used. And at least one selected from the group consisting of bis (thiocarbonyl) disulfide compounds and trithiocarbonate compounds can be used more preferably. When a relatively low activity monomer such as vinyl acetate or N-vinylpyrrolidone is used as the monomer (B), one or more of a dithiocarbamate compound and a xanthate compound can be preferably used. In addition, a thiocarbonylthio compound (A) can be used individually by 1 type in the above or in combination of 2 or more types.

The graft copolymer of the present invention is produced by a method including a step of polymerizing the monomer (B) in the presence of the thiocarbonylthio compound (A). Specific embodiments of this production method include, for example, the following method [1] and method [2].
[1] A method for producing a graft copolymer by polymerizing the monomer (B) in the presence of the thiocarbonylthio compound (A) and the polymer (D) having a double bond in the side chain.
[2] The monomer (B) is polymerized in the presence of the thiocarbonylthio compound (A), and then the polymerization product obtained by the polymerization and the polymer (D) having a double bond in the side chain In the presence of a radical generator to produce a graft copolymer.

<About Method [1]>
In the method [1], the target graft copolymer is grown by polymerizing a double bond (for example, 1,2-vinyl bond) on the polymer (D) and a monomer (B) to grow a branch polymer. Synthesize coalescence. The proportion of the monomer (B) used in the method [1] may be appropriately set according to the amount of graft chain introduced and the molecular weight of the graft chain portion, but is preferably based on 100 parts by mass of the polymer (D). Is 1 to 1,000 parts by mass, more preferably 10 to 500 parts by mass.
The ratio of the thiocarbonylthio compound (A) used in the polymerization is preferably 0.05 to 20 parts by mass, more preferably 0.1 to 10 parts by mass with respect to 100 parts by mass of the monomer (B). Part by mass. Further, when the polymerization of the monomer (B) is carried out in the presence of the radical generator (C), the usage ratio of the radical generator (C) is based on 100 parts by mass of the monomer (B) in total. Preferably it is 0.01-20 mass parts, More preferably, it is 0.1-10 mass parts.

Method [1] can be carried out by solution polymerization. As the polymerization method, either a batch type or a continuous type may be used. The solvent (E) used is an organic solvent inert to the reaction and can dissolve the polymer (D) (preferably soluble at room temperature). For example, aliphatic hydrocarbons, alicyclic Hydrocarbon solvents such as hydrocarbons and aromatic hydrocarbons can be preferably used. Specific examples thereof include aliphatic hydrocarbons such as n-hexane, n-heptane, 1-hexene, 2-hexene, 1-pentyne, 2-pentyne and the like; alicyclic hydrocarbons such as cyclo Examples of the aromatic hydrocarbon include pentane, cyclohexane, methylcyclopentane, methylcyclohexane, cyclohexene, and the like. Examples of the aromatic hydrocarbon include benzene, toluene, xylene, and ethylbenzene. Of these solvents, alicyclic hydrocarbons, aromatic hydrocarbons or mixtures thereof are preferred, and toluene is more preferred. In addition, a solvent (E) can be used individually by 1 type or in combination of 2 or more types.
The use ratio of the solvent (E) in the case of solution polymerization may be appropriately set according to the solubility of the polymer (D) in the solvent, etc., but from the viewpoint of reaction efficiency, the proportion of the solvent (E) is 100 parts by mass of the polymer (D). On the other hand, it is preferable to set it as 30-1,000 mass parts, and it is more preferable to set it as 50-800 mass parts.

  The polymer (D), monomer (B), radical generator (C), thiocarbonylthio compound (A) and solvent (E) used in the reaction are each independently or before being subjected to the polymerization reaction. It is preferable to previously treat a mixture of two or more of these with a polymerization inhibitor such as impurity hydroquinone using alumina. By this treatment, the polymerization termination reaction due to impurities can be suitably suppressed, and a high polymerization conversion rate of the monomer used for the reaction can be achieved.

  The polymerization temperature is not particularly limited as long as radical polymerization can proceed, but it is preferably 0 ° C. or more from the viewpoint of productivity, and more preferably in the range of 0 ° C. to 140 ° C. It is more preferable to set it as the range of 20-100 degreeC, and it is especially preferable to set it as the range of 50-90 degreeC. The polymerization temperature is preferably set considering that the polymerization reaction is an exothermic reaction. The polymerization temperature can be controlled by adjusting the feed rate and temperature of the radical generator (C), monomer (B) and solvent (E), and cooling and heating from the outside of the reactor. The polymerization reaction is preferably carried out under a pressure sufficient to keep the monomer in a substantially liquid phase. The polymerization reaction time is preferably 30 minutes to 20 hours, more preferably 1 to 10 hours.

  Thus, a polymer solution containing the graft copolymer of the present invention is obtained. As a method for isolating the polymer from the polymer solution, a conventionally known method can be employed. Specifically, for example, the solvent is separated by, for example, steam stripping, and then the polymer is filtered and further dehydrated and dried to obtain the polymer; the polymer is concentrated in a flushing tank, and further removed by a vent extruder or the like. A method of volatilizing; a method of directly volatilizing with a drum dryer or the like;

<About Method [2]>
In the method [2], the monomer (B) is first polymerized in the presence of the thiocarbonylthio compound (A) to synthesize a branched polymer, and the resulting branched polymer terminal group (thiocarbonylthio group) is generated as a radical. The target graft copolymer is synthesized by a two-step reaction in which it reacts with a reactive site (1,2-vinyl bond, etc.) on the polymer (D) by reactivation with an agent.

  In the polymerization step for polymerizing the monomer (B), the ratio of the thiocarbonylthio compound (A) used is preferably 0.1 to 100 parts by mass with respect to 100 parts by mass of the monomer (B) in total. Yes, more preferably 5 to 50 parts by mass. When the polymerization of the monomer (B) is performed in the presence of the radical generator (C), the ratio of the radical generator (C) used is preferably 1 with respect to 100 parts by mass of the thiocarbonylthio compound (A). ˜1,000 parts by mass, more preferably 10 to 100 parts by mass.

The polymerization of the monomer (B) is preferably performed by solution polymerization. Moreover, any of a batch type and a continuous type may be used for the polymerization method. The description of the above method [1] can be applied to the type and proportion of the solvent (E) used in the solution polymerization. The polymerization of the monomer (B) is preferably performed in the absence of the polymer (D) from the viewpoint of easily adjusting the graft ratio and increasing the reactivity in the next step.
The polymerization temperature of the monomer (B) may be a temperature at which radical polymerization can proceed, and the explanation of the polymerization temperature of the above method [1] can be applied to a preferable range. The polymerization time is preferably 30 minutes to 15 hours, more preferably 1 to 8 hours.

  Thus, a solution containing a polymer having a structural unit derived from the monomer (B) is obtained. This polymer solution may be used for the next step as it is, may be used for the next step after isolating the polymer contained in the polymer solution, or after purifying the isolated polymer. You may use for the following process. For the method of isolating the polymer from the polymer solution, the explanation in the above method [1] can be applied.

  Next, the polymerization product (branched polymer) obtained by the polymerization is reacted with the polymer (D) in the presence of a radical generator (grafting step). Specific examples of the radical generator used in this step include compounds exemplified as the radical generator (C) that may be used in the polymerization of the monomer (B). In addition, the radical generator used at this process may be the same as the compound used for superposition | polymerization of a monomer (B), and may differ.

  The reaction between the polymerization product and the polymer (D) is preferably carried out in an organic solvent. From the viewpoint of productivity, it is preferable to use the polymer solution obtained in the polymerization step as it is and add the polymer (D) and an additional radical generator to the reaction solution. In that case, the total use ratio of the monomer (B) to 100 parts by mass of the polymer (D) is preferably 5 to 300 parts by mass, and more preferably 10 to 150 parts by mass. It is desirable to set the usage ratio of the monomer (B) and the usage ratio of the polymer (D) in this step. The use ratio of the additional radical generator is preferably 1 to 1,000 parts by mass, more preferably 10 to 100 parts by mass with respect to 100 parts by mass of the thiocarbonylthio compound (A).

The reaction temperature between the polymerization product and the polymer (D) is preferably 0 ° C. or more, more preferably in the range of 0 ° C. to 140 ° C. from the viewpoint of productivity, and in the range of 20 to 100 ° C. It is more preferable that the temperature be in the range of 50 to 90 ° C. The reaction time is preferably 30 minutes to 15 hours, more preferably 1 to 8 hours.
Thus, a polymer solution containing the graft copolymer of the present invention is obtained. Regarding the method for isolating the polymer from the polymer solution, the explanation in the above method [1] can be applied. In the above method [2], since a radical chain transfer group is present in the polymerization system by carrying out the polymerization using the thiocarbonylthio compound (A), the gel is obtained by the graft-to method of the polymer (D). It is presumed that conversion will not proceed.

The graft copolymer produced by the production method of the present invention (including the above method [1] and method [2]) has a graft ratio of, for example, 0.5 to 50% by mass, preferably 1 to 40% by mass. %, More preferably 2 to 30% by mass. This graft ratio is a mass ratio (%) of a graft chain (branched polymer) in one molecule of the graft copolymer. The graft ratio is a value measured by ¹ H-NMR.
According to the above production method, a graft copolymer having a gel content of 1% by mass or less, preferably 0.8% by mass or less, more preferably 0.7% by mass or less can be obtained. The gel content is a value obtained by charging and refluxing the polymer after drying into a polymerization solvent and then filtering with a wire mesh, and measuring the mass increase of the wire mesh when the wire mesh is dried.

The weight average molecular weight (Mw) in terms of polystyrene by GPC in the graft chain portion of the graft copolymer of the present invention is preferably 0.1 × 10 ^{5 to} 2.0 × 10 ⁶ , more preferably 0.3. × ¹⁰ 5 to 1.5 is × 10 ^6, more preferably from ^{0.5 × 10 5 ~1.0 × 10 6} . Further, the molecular weight distribution (Mw / Mn) represented by the ratio of the weight average molecular weight (Mw) and the number average molecular weight (Mn) in the graft polymer of the present invention is preferably 1.0 to 10.0. 1.0 to 8.0 is more preferable.

<Polymer composition and pressure-sensitive adhesive>
The polymer composition of this invention contains the graft copolymer obtained by the manufacturing method of this invention as a polymer component. The graft copolymer and polymer composition of the present invention can be used for various applications such as pressure-sensitive adhesives, dispersants, compatibilizers, footwear materials, various automobile parts, industrial products, asphalt compositions, etc. Among them, it can be preferably applied to an adhesive.

  The pressure-sensitive adhesive of the present invention contains one or more graft copolymers obtained by the above production method and other optional components added as necessary. Other optional components include, for example, tackifiers, polyolefin resins, antioxidants, ultraviolet absorbers, colorants, light stabilizers, thermal polymerization inhibitors, antifoaming agents, leveling agents, antistatic agents, surfactants, Examples include storage stabilizers and fillers. These optional components can be appropriately used in the types and amounts generally used for pressure-sensitive adhesives. The blending ratio of an optional component (for example, a tackifier) in the pressure-sensitive adhesive is preferably 0 to 30% by mass, and more preferably 0 to 20% by mass.

  By applying the pressure-sensitive adhesive of the present invention on a base material to form a pressure-sensitive adhesive layer, a pressure-sensitive adhesive body having a base material layer and a pressure-sensitive adhesive layer can be produced. The base material can be appropriately selected according to the purpose, for example, high density polyethylene, linear low density polyethylene, polypropylene, polyolefin such as ethylene / propylene copolymer, polyethylene terephthalate, polyester such as polybutylene terephthalate, Examples thereof include polyamides such as nylon 6 and nylon 66. The pressure-sensitive adhesive obtained using the pressure-sensitive adhesive of the present invention can be applied to, for example, pressure-sensitive adhesive tapes, pressure-sensitive adhesive sheets, pressure-sensitive adhesive films and the like, and can be used in various fields such as industrial, architectural, and medical purposes.

EXAMPLES Hereinafter, although this invention is demonstrated concretely based on an Example, this invention is not limited to these Examples. In the examples and comparative examples, “parts” and “%” are based on mass unless otherwise specified. The measuring method of various physical property values of the polymer is as follows.

[Mass average molecular weight Mw and number average molecular weight Mn]
It calculated | required in polystyrene conversion from the retention time corresponded to the vertex of the maximum peak of the GPC curve obtained using the gel permeation chromatography (Brand name "HLC-8120GPC", the Tosoh company make) on the following conditions.
Column: Two brand names “GMHXL” (manufactured by Tosoh Corporation) Column temperature: 40 ° C.
Mobile phase; tetrahydrofuran flow rate; 1.0 ml / min sample concentration; 10 mg / 20 ml
[Ratio of branch polymer in one molecule of graft polymer (graft ratio)]
The graft ratio [mass%] was measured using ¹ H-NMR. 400 MHz-NMR (manufactured by Bruker, AVANCEIII, AV400N) was used as a measurement apparatus, and CDCl ₃ was used as a measurement solvent.
[Gel content]
The gel content [% by mass] was determined by adding 1 g of the dried polymer to 100 ml of the same solvent used in the polymerization, refluxing for 2 hours, and filtering with a pre-weighed 80 mesh stainless steel wire mesh. It calculated | required by making it vacuum-dry at 100 degreeC for 1 hour, and measuring the mass increase. The polymer solution was filtered and then washed once with 20 ml of solvent.

[Example 1: Synthesis of polymer (P-1)]
A 500 ml pressure bottle was purged with nitrogen, and 1.3 parts by mass of tetramethylthiuram disulfide as the thiocarbonylthio compound (A) (controlling agent), 35.2 parts by mass of toluene as the polymerization solvent (E), and monomer (B) 35.0 parts by weight of methyl methacrylate, 11.7 parts by weight of a toluene solution (200 mM) of azobisisobutyronitrile (AIBN) as a radical generator (C), and a butadiene-based polymer (D) having a double bond in the side chain 16.9 parts by mass of a polymer (RB810 manufactured by JSR Corporation) was charged to obtain a composition for polymerization.

Next, the pressure-resistant bottle containing the polymerization composition was heated at 80 ° C. for 7 hours using an oil bath, and graft polymerization was performed to obtain a polymer solution. The polymer solution was reprecipitated in acetone to remove impurities, and then dried at 60 ° C. for 15 hours using a vacuum dryer to obtain a polymer (P-1).
During the polymerization, the reaction mixture containing the polymer was appropriately extracted, the volatile components contained in the mixture were removed, the solid content concentration was determined, and the polymerization conversion rate (%) of the monomer was calculated to be 61%. It was. Moreover, when the weight average molecular weight Mw of the graft chain part of the obtained polymer (P-1) and the ratio (Mw / Mn) of the weight average molecular weight Mw and the number average molecular weight Mn were measured, Mw = 722,900. Mw / Mn = 5.15. The graft ratio was 12.9% by mass. Moreover, the polymer (P-1) was not gelatinized. “Gelification” refers to a state in which the system has lost fluidity, and was confirmed visually. Furthermore, it was 0.4 mass% when the gel content of the obtained polymer (P-1) was measured.

[Examples 2 to 7: Synthesis of polymer (P-2) to polymer (P-7)]
The types and amounts of the thiocarbonylthio compound (A), monomer (B), radical generator (C), polymer (D) and polymerization solvent (E) used, and polymerization conditions are changed as shown in Table 1 below. Except that, graft polymerization was carried out in the same manner as in Example 1 to obtain polymers (P-2) to (P-7), respectively. The physical properties of the obtained polymer are also shown in Table 1 below.

In Table 1, the numerical values of the thiocarbonylthio compound (A), the monomer (B), the polymer (D) and the polymerization solvent (E) indicate the blending ratio (parts by mass) in the polymer composition. The abbreviations of the compounds are as follows.
<Thiocarbonylthio compound (A)>
A-1-1; tetramethylthiuram disulfide A-1-2; S- (2-cyano-2-propyl) -S-dodecyltrithiocarbonate (200 mM toluene solution)
<Monomer (B)>
B-1-1; methyl methacrylate B-1-2; 2-hydroxyethyl methacrylate B-1-3; glycidyl methacrylate B-1-4; 2- (dimethylamino) ethyl methacrylate B-1-5 ; 2-methoxyethyl acrylate <radical generator (C)>
AIBN; azobisisobutyronitrile (200 mM toluene solution)
<Polymer (D) having double bond in side chain>
RB810; butadiene polymer manufactured by JSR Corporation, trade name “RB810”
TR2000; styrene-butadiene copolymer manufactured by JSR Corporation, trade name “TR2000”

[Example 8: Synthesis of polymer (P-8)]
A 500 ml pressure bottle was replaced with nitrogen, and 2.5 parts by mass of a toluene solution (200 mM) of S- (2-cyano-2-propyl) -S-dodecyltrithiocarbonate as a thiocarbonylthio compound (A), a polymerization solvent (E) 71 parts by mass of toluene, 10.8 parts by mass of methyl methacrylate as the vinyl monomer (B), 0.6 parts by mass of a toluene solution (200 mM) of azobisisobutyronitrile as the radical generator (C), Each was charged and polymerized at 80 ° C. for 2 hours. After 2 hours from the start of the polymerization, 8.0 parts by mass of a butadiene polymer (RB810 manufactured by JSR) as a polymer (D) having a double bond in the side chain, and azobisiso as an additional radical generator (C ′) 6.0 parts by mass of a toluene solution of butyronitrile (200 mM) was added to the reaction system and reacted at 80 ° C. for 7 hours to obtain a polymer (P-8). Table 2 shows the measurement results of the physical properties of the polymer (P-8) obtained.

[Comparative Example 1: Synthesis of polymer (R-1)]
The points of not using the thiocarbonylthio compound (A), the types and amounts of the monomer (B), radical generator (C), polymer (D) and polymerization solvent (E) used are shown in Table 1 above. A polymer (R-1) was obtained in the same manner as in Example 1 except that the points were as described above and the polymerization conditions were as shown in Table 1 above. The physical properties of the obtained polymer are also shown in Table 1 above.

  As shown in Table 1, in Examples 1 to 8 in which the monomer (B) was polymerized in the presence of the thiocarbonylthio compound (A), a highly stable graft copolymer without gelation was obtained. It was. On the other hand, in Comparative Example 1 in which the polymerization was performed without using the thiocarbonylthio compound (A), the product was gelled and insoluble in solvents such as THF and toluene.

Claims (3)

A method for producing a graft copolymer obtained by grafting a polymer (D) having a double bond in a side chain with a monomer (B) having a radical polymerizable unsaturated bond,
A method for producing a graft copolymer, comprising a polymerization step of polymerizing the monomer (B) in the presence of a thiocarbonylthio compound (A) and the polymer (D) in a hydrocarbon solvent .   The method for producing a graft copolymer according to claim 1, wherein the polymerization step is performed in the presence of a radical generator. The method for producing a graft copolymer according to claim 1 or 2 , wherein the polymer (D) has a structural unit derived from butadiene.