Block copolymer composition, and molded product formed by molding the block copolymer composition

Abstract

To provide a block copolymer composition capable of providing a molded product which is excellent in flexibility, tensile strength, and resilience.SOLUTION: Provided is a block copolymer composition comprising a block copolymer A represented by general formula (A) and a block copolymer B represented by general formula (B), in which: a content of an aromatic vinyl monomer unit in the block copolymer (A) is 10-30 wt.%, and a weight-average molecular weight thereof is 80,000-150,000; a content of the aromatic vinyl monomer unit in the block copolymer (B) is 40-65 wt.%, and a weight-average molecular weight thereof is 300,000-500,000; and a weight ratio (A / B) of the block polymer A to the block polymer B is 45 / 55-90 / 10. Ar1a-Da-Ar2a (A), Ar1b-Db-Ar2b (B).SELECTED DRAWING: None

Description

[Technical field]

[0001] The present invention relates to a block copolymer composition and a molded article obtained by molding the block copolymer composition. [Background technology]

[0002] Aromatic vinyl-conjugated diene-aromatic vinyl block copolymers such as styrene-isoprene-styrene block copolymer (SIS) and styrene-butadiene-styrene block copolymer (SBS) are thermoplastic elastomers with characteristic properties in various aspects, and therefore are used in a variety of applications. Among thermoplastic elastomers, aromatic vinyl-conjugated diene-aromatic vinyl block copolymers are particularly elastic and flexible, and therefore are suitably used for stretch materials such as surgical gloves, sanitary materials, masks, and underwear.

[0003] For example, Patent Document 1 discloses that an elastomeric polymer blend composition comprising 65 to 92 parts by weight of a specific elastomeric monovinylidene aromatic-conjugated diene block copolymer having a monovinylidene aromatic content of less than 50% by weight and 8 to 35 parts by weight of a specific thermoplastic monovinylidene aromatic-conjugated diene block copolymer having a monovinylidene aromatic content of 50% by weight or more can provide an elastomeric article exhibiting excellent elasticity and stress relaxation properties. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Special Publication No. 2006-528273 Summary of the Invention [Problem to be solved by the invention]

[0005] Stretchable materials for surgical gloves and the like that are used in contact with the skin are required to be comfortable to wear, not to be too tight, and to be flexible, not to break even when pulled hard, and not to deform significantly, so that they can be used stably for a long period of time. That is, the stretchable material is required to have flexibility, tensile strength, and restoring force. On the other hand, the technology described in Patent Document 1 has room for improvement in terms of achieving both flexibility, tensile strength, and restoring force. The problem to be solved by the present invention is to provide a block copolymer composition that can give a molded article having excellent flexibility, tensile strength, and restoring force. [Means for solving the problem]

[0006] Means for Solving the Problems The present inventors have conducted intensive research to solve the above problems, and as a result have found that, in a block copolymer composition containing two types of block copolymers having specific structures, the above problems can be solved by controlling the contents of aromatic vinyl monomer units and weight average molecular weights of the two types of block copolymers within specific ranges and by controlling the weight ratio of the two types of block copolymers within specific ranges. Based on this finding, the present inventors have completed the present invention.

[0007] [1] According to a first aspect of the present invention, there is provided a block copolymer composition comprising a block copolymer A represented by the following general formula (A) and a block copolymer B represented by the following general formula (B), wherein the content of aromatic vinyl monomer units in the block copolymer (A) is 10 to 30% by weight, the content of aromatic vinyl monomer units in the block copolymer (B) is 40 to 65% by weight, the weight average molecular weight of the block copolymer (A) is 80,000 to 150,000, the weight average molecular weight of the block copolymer (B) is 300,000 to 500,000, and the weight ratio (A / B) of the block copolymer A to the block copolymer B is 45 / 55 to 90 / 10. Ar1 a -D a -Ar2 a (A) Ar1 b-D b -Ar2 b (B) (In the general formulas (A) and (B), Ar1 a , Ar2 a , Ar1 b , and Ar2 b are aromatic vinyl polymer blocks, and D a and D. b are conjugated diene polymer blocks, and Ar1 a Weight average molecular weight of Ar2 a The ratio of weight average molecular weight (Mw(Ar2 a ) / Mw(Ar1 a )) is 0.9 to 1.1, and Ar1 b Weight average molecular weight of Ar2 b The ratio of weight average molecular weight (Mw(Ar2 b ) / Mw(Ar1 b )) is 0.9 to 1.1.

[0008] [2] According to the second aspect of the present invention, in the general formula (B), Ar1 b , and Ar2 b The block copolymer composition according to the first aspect is provided, wherein each of the weight average molecular weights of the copolymers is 80,000 to 150,000.

[0009] [3] According to a third aspect of the present invention, there is provided the block copolymer composition according to the first or second aspect, wherein the proportion of aromatic vinyl monomer units in all repeating units of the polymer component of the block copolymer composition is 20 to 44% by weight.

[0010] [4] According to a fourth aspect of the present invention, there is provided the block copolymer composition according to any one of the first to third aspects, wherein, in general formulas (A) and (B), a ratio (Mw(B) / Mw(A)) of the weight average molecular weight (Mw(B)) of the block copolymer (B) to the weight average molecular weight (Mw(A)) of the block copolymer (A) is 3 to 5.

[0011] [5] According to the fifth aspect of the present invention, in the general formulas (A) and (B), Ar1a Ar1 relative to the weight average molecular weight of b The ratio of weight average molecular weight (Mw(Ar1 b ) / Mw(Ar1 a 5. The block copolymer composition according to any one of Aspects 1 to 4, wherein R 1 is 3.0 to 30.

[0012] [6] According to a sixth aspect of the present invention, there is provided a molded article obtained by molding the block copolymer composition according to any one of the first to fifth aspects. Effect of the Invention

[0013] According to the present invention, it is possible to provide a block copolymer composition having excellent flexibility, tensile strength, and restoring force. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0014] The block copolymer composition of the present invention comprises a block copolymer A represented by the following general formula (A) and a block copolymer B represented by the following general formula (B), wherein the content of aromatic vinyl monomer units in the block copolymer (A) is 10 to 30% by weight, the content of aromatic vinyl monomer units in the block copolymer (B) is 40 to 65% by weight, the weight average molecular weight of the block copolymer (A) is 80,000 to 150,000, the weight average molecular weight of the block copolymer (B) is 300,000 to 500,000, and the weight ratio (A / B) of the block copolymer A to the block copolymer B is 45 / 55 to 90 / 10. Ar1 a -D a -Ar2 a (A) Ar1 b -D b -Ar2 b (B)

[0015] In the general formulas (A) and (B), Ar1 a , Ar2 a , Ar1 b , and Ar2 bare aromatic vinyl polymer blocks, and D a and D. b are conjugated diene polymer blocks, and Ar1 a Weight average molecular weight of Ar2 a The ratio of weight average molecular weight (Mw(Ar2 a ) / Mw(Ar1 a )) is 0.9 to 1.1, and Ar1 b Weight average molecular weight of Ar2 b The ratio of weight average molecular weight (Mw(Ar2 b ) / Mw(Ar1 b ) is 0.9 to 1.1.

[0016] Aromatic vinyl polymer block Ar1 of block copolymer A a , Ar2 a , and the aromatic vinyl polymer block Ar1 of the block copolymer B b , Ar2 b are polymer blocks constituted by aromatic vinyl monomer units.

[0017] The aromatic vinyl monomer used to constitute the aromatic vinyl monomer unit is not particularly limited as long as it is an aromatic vinyl compound. Examples of aromatic vinyl compounds include styrene; styrenes substituted with alkyl groups such as α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, and 5-t-butyl-2-methylstyrene; styrenes substituted with halogen atoms such as 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, and 2,4-dibromostyrene; and vinylnaphthalene. Among these, it is preferable to use styrene. These aromatic vinyl monomers can be used alone or in combination of two or more in each aromatic vinyl polymer block. In addition, the same aromatic vinyl monomer may be used in each aromatic vinyl polymer block, or different aromatic vinyl monomers may be used.

[0018] The content of the aromatic vinyl monomer unit in the block copolymer A is 10 to 30% by weight, and preferably 15 to 25% by weight. By setting the content of the aromatic vinyl monomer unit within the above range, a molded article obtained from the block copolymer composition can be made excellent in flexibility, tensile strength, and restoring force.

[0019] The content of the aromatic vinyl monomer unit in the block copolymer B is 40 to 65% by weight, and preferably 50 to 65% by weight. By setting the content of the aromatic vinyl monomer unit within the above range, a molded article obtained from the block copolymer composition can be made excellent in flexibility, tensile strength, and restoring force.

[0020] Aromatic vinyl polymer block Ar1 a , Ar2 a , Ar1 b , and Ar2 bmay each contain a monomer unit other than the aromatic vinyl monomer unit. Examples of monomers constituting the monomer units other than the aromatic vinyl monomer unit include conjugated diene monomers such as 1,3-butadiene and isoprene (2-methyl-1,3-butadiene); α,β-unsaturated nitrile monomers; unsaturated carboxylic acid or acid anhydride monomers; unsaturated carboxylic acid ester monomers; and non-conjugated diene monomers.

[0021] The content of monomer units other than aromatic vinyl monomer units in each aromatic vinyl polymer block is preferably 20% by weight or less, more preferably 10% by weight or less, and particularly preferably substantially 0% by weight, based on the entire aromatic vinyl polymer block.

[0022] Aromatic vinyl polymer block Ar1 in block copolymer A a , Ar2 a Weight average molecular weight (Mw(Ar1 a ), Mw(Ar2 a )) is preferably 2,000 to 40,000, more preferably 3,000 to 20,000, and further preferably 4,000 to 10,000. a Weight average molecular weight (Mw(Ar1 a )) for Ar2 a Weight average molecular weight (Mw(Ar2 a )) ratio (Mw(Ar2 a ) / Mw(Ar1 a )) is 0.9 to 1.1, preferably 0.95 to 1.05, and more preferably 1. That is, the two aromatic vinyl polymer blocks Ar1 a and Ar2 a The weight average molecular weight of the block copolymer A is the same as that of the aromatic vinyl polymer block Ar1. a , a conjugated diene polymer block D, and an aromatic vinyl polymer block Ar2 a It is preferable that the second electrode has a symmetrical structure in which the first electrode and the second electrode are connected in series.

[0023] Aromatic vinyl polymer block Ar1 in block copolymer Bb , Ar2 b Weight average molecular weight (Mw(Ar1 b ), Mw(Ar2 b )) is preferably 40,000 to 200,000, more preferably 50,000 to 180,000, and further preferably 60,000 to 150,000. b Weight average molecular weight (Mw(Ar1 b )) for Ar2 b Weight average molecular weight (Mw(Ar2 b )) ratio (Mw(Ar2 b ) / Mw(Ar1 b )) is 0.9 to 1.1, preferably 0.95 to 1.05, and more preferably 1. That is, the two aromatic vinyl polymer blocks Ar1 b and Ar2 b The weight average molecular weight of the block copolymer B is the same as that of the aromatic vinyl polymer block Ar1. b , a conjugated diene polymer block D, and an aromatic vinyl polymer block Ar2 b It is preferable that the aryl group has a symmetric structure in which Mw(Ar1 b ), Mw(Ar2 b ), and (Mw(Ar2 b ) / Mw(Ar1 b By setting each of the above-mentioned ranges, a molded article obtained from the block copolymer composition can be excellent in flexibility, tensile strength, and restoring force.

[0024] Conjugated diene polymer block D of block copolymer A a and the conjugated diene polymer block D of the block copolymer B b is a polymer block composed of conjugated diene monomer units.

[0025] The conjugated diene monomer used to form the conjugated diene monomer unit is not particularly limited as long as it is a conjugated diene compound. Examples of the conjugated diene compound include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, and 1,3-hexadiene. Among these, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. By forming the polymer block of the conjugated diene polymer from an isoprene unit, it is possible to obtain a block copolymer composition having excellent flexibility and a smaller permanent elongation. These conjugated diene monomers can be used alone or in combination of two or more kinds in each polymer block. In addition, the same conjugated diene monomer may be used in each polymer block, or different conjugated diene monomers may be used.

[0026] Conjugated diene polymer block D a , D b may each contain a monomer unit other than the conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than the conjugated diene monomer unit include aromatic vinyl monomers such as styrene and α-methylstyrene, α,β-unsaturated nitrile monomers, unsaturated carboxylic acid or acid anhydride monomers, unsaturated carboxylic acid ester monomers, and non-conjugated diene monomers.

[0027] The content of monomer units other than the conjugated diene monomer in each conjugated diene polymer block is preferably 20% by weight or less, more preferably 10% by weight or less, and particularly preferably substantially 0% by weight, based on the entire conjugated diene polymer block.

[0028] Conjugated diene polymer block D a Weight average molecular weight (Mw(D a )) is preferably 70,000 to 140,000, more preferably 75,000 to 130,000, and further preferably 80,000 to 120,000. bWeight average molecular weight (Mw(D b )) is preferably 80,000 to 420,000, more preferably 120,000 to 360,000, and even more preferably 160,000 to 240,000.

[0029] The weight ratio (A / B) of block copolymer A to block copolymer B contained in the block copolymer composition is 45 / 55 to 90 / 10, preferably 45 / 55 to 80 / 20, and more preferably 45 / 55 to 70 / 30. By setting the weight ratio (A / B) within the above range, a molded article obtained from the block copolymer composition can be made excellent in flexibility, tensile strength, and restoring force.

[0030] Ar1 in block copolymer A a Weight average molecular weight (Mw(Ar1 a )) in block copolymer B b Weight average molecular weight (Mw(Ar1 b )) ratio (Mw(Ar1 b ) / Mw(Ar1 a Mw(Ar1) is preferably 3.0 to 30, more preferably 4.0 to 25, and further preferably 5.0 to 20. b ) / Mw(Ar1 a ) in the above range, a molded article obtained from the block copolymer composition can have even better flexibility, tensile strength, and restoring force.

[0031] The weight average molecular weight (Mw(A)) of the block copolymer A is 80,000 to 150,000, preferably 85,000 to 140,000, and more preferably 90,000 to 130,000. By setting Mw(A) within the above range, a molded article obtained from the block copolymer composition can be made excellent in flexibility, tensile strength, and restoring force.

[0032] The weight average molecular weight (Mw(B)) of the block copolymer B is 300,000 to 500,000, preferably 330,000 to 490,000, and more preferably 360,000 to 480,000. By setting Mw(B) within the above range, a molded article obtained from the block copolymer composition can be made excellent in flexibility, tensile strength, and restoring force.

[0033] The ratio of the weight average molecular weight Mw(B) of block copolymer B to the weight average molecular weight Mw(A) of block copolymer A (Mw(B) / Mw(A)) is preferably 3 to 5, more preferably 3.2 to 4.8, and even more preferably 3.5 to 4.5. By setting Mw(B) / Mw(A) in the above range, a molded article obtained from the block copolymer composition can be made to have even more excellent flexibility, tensile strength, and restoring force.

[0034] The proportion of aromatic vinyl monomer units in the total repeating units of the polymer components of the block copolymer composition is preferably 20 to 44% by weight, more preferably 30 to 43% by weight. If the proportion of aromatic vinyl monomer units in the total repeating units is too large, the block copolymer composition and the stretch material obtained using the block copolymer composition will have poor balance of stress, tensile strength, and residual strain at low elongation. The total aromatic vinyl monomer unit content can be easily adjusted by taking into account the aromatic vinyl monomer unit content of each of the block copolymer A, block copolymer B, and other polymer components constituting the block copolymer composition, and adjusting the blending amount of them.

[0035] When all the polymer components constituting the block copolymer composition are composed only of aromatic vinyl monomer units and conjugated diene monomer units, the polymer components in the block copolymer composition are decomposed by ozonolysis according to the method described in Rubber Chem. Technol., 45, 1295 (1972), followed by reduction with lithium aluminum hydride. This decomposes the conjugated diene monomer unit portions, allowing only the aromatic vinyl monomer unit portions to be extracted, and therefore the total aromatic vinyl monomer unit content can be easily measured.

[0036] The block copolymer composition of the present invention may contain only block copolymer A and block copolymer B as polymer components, but may also contain polymer components other than block copolymer A and block copolymer B within a range that does not impair the effects of the present invention.

[0037] Examples of polymer components other than block copolymer A and block copolymer B that may be contained in the block copolymer composition of the present invention include aromatic vinyl-conjugated diene-aromatic vinyl block copolymers other than block copolymer A and block copolymer B, aromatic vinyl-conjugated diene block copolymers, aromatic vinyl homopolymers, conjugated diene homopolymers, aromatic vinyl-conjugated diene random copolymers, and branched polymers thereof; thermoplastic elastomers such as polyurethane-based thermoplastic elastomers, polyamide-based thermoplastic elastomers, and polyester-based thermoplastic elastomers; thermoplastic resins such as polyethylene, polypropylene, polyvinyl chloride, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, and polyphenylene ether; and the like.

[0038] In the block copolymer composition of the present invention, the content of polymer components other than block copolymer A and block copolymer B is preferably 20% by weight or less, more preferably 10% by weight or less, based on the total amount of polymer components. It is further preferable that the block copolymer composition does not substantially contain any polymer components other than block copolymer A and block copolymer B.

[0039] The block copolymer composition of the present invention may contain components other than the polymer components as necessary, such as antioxidants, softeners, tackifiers, antibacterial agents, light stabilizers, UV absorbers, dyes, lubricants, crosslinking agents, and crosslinking accelerators.

[0040] Examples of the antioxidant include hindered phenol compounds such as pentaerythritol tetrakis [3- (3,5-di-t-butyl-4-hydroxyphenyl) propionate], 2,6-di-t-butyl-p-cresol, and di-t-butyl-4-methylphenol; thiodicarboxylate esters such as dilauryl thiopropionate; and phosphites such as tris (nonylphenyl) phosphite. The antioxidant may be used alone or in combination of two or more. The content of the antioxidant is not particularly limited, but is preferably 10 parts by weight or less, more preferably 0.5 to 5 parts by weight, in 100 parts by weight of the block copolymer composition.

[0041] The method for producing the block copolymer composition of the present invention is not particularly limited. For example, according to a conventional method for producing block copolymers, block copolymer A and block copolymer B are separately produced, and other polymer components and various additives are blended as necessary, and then they are mixed according to a conventional method such as kneading or solution mixing, thereby producing the block copolymer composition of the present invention.

[0042] The block copolymer A is preferably produced by a method in which an aromatic vinyl monomer, a conjugated diene monomer, and an aromatic vinyl monomer are sequentially polymerized in this order to form a polymer block. Specifically, the block copolymer A is preferably produced by the following method. That is, first, an aromatic vinyl monomer is polymerized in a solvent using a polymerization initiator to obtain a solution containing an aromatic vinyl polymer having an active terminal.

[0043] As the polymerization initiator, a polymerization initiator known to have an anionic polymerization activity for aromatic vinyl monomers and conjugated diene monomers can be used, such as an organic alkali metal compound, an organic alkaline earth metal compound, an organic lanthanoid series rare earth metal compound, etc.

[0044] As the organic alkali metal compound, an organic lithium compound having one or more lithium atoms in the molecule is particularly preferably used.Specific examples of the organic alkali metal compound include organic monolithium compounds such as ethyl lithium, n-propyl lithium, isopropyl lithium, n-butyl lithium, sec-butyl lithium, t-butyl lithium, hexyl lithium, phenyl lithium, stilbene lithium, dialkylamino lithium, diphenylamino lithium, and ditrimethylsilylamino lithium; organic dilithium compounds such as methylene dilithium, tetramethylene dilithium, hexamethylene dilithium, isoprenyl dilithium, and 1,4-dilithio-ethylcyclohexane; and organic trilithium compounds such as 1,3,5-trilithiobenzene; and the like.Among these, organic monolithium compounds are particularly preferably used.

[0045] Examples of the organic alkaline earth metal compounds include n-butyl magnesium bromide, n-hexyl magnesium bromide, ethoxy calcium, calcium stearate, t-butoxy strontium, ethoxy barium, isopropoxy barium, ethylmercapto barium, t-butoxy barium, phenoxy barium, diethylamino barium, barium stearate, and ethyl barium.

[0046] In addition to the above, a composite catalyst consisting of a lanthanoid series rare earth metal compound containing neodymium, samarium, gadolinium, etc. / alkylaluminum / alkylaluminum halide / alkylaluminum hydride, or a metallocene type catalyst containing titanium, vanadium, samarium, gadolinium, etc., which becomes a homogeneous system in an organic solvent and has living polymerizability, can also be used.

[0047] The polymerization initiator may be used alone or in combination of two or more. The amount of the polymerization initiator used may be determined according to the molecular weight of each target block copolymer and is not particularly limited, but is preferably 0.01 to 20 mmol, more preferably 0.05 to 15 mmol, and further preferably 0.1 to 10 mmol per 100 g of the total monomers used in the polymerization.

[0048] The solvent used in the polymerization is not particularly limited as long as it is inactive against the polymerization initiator, and examples thereof include chain hydrocarbon solvents, cyclic hydrocarbon solvents, and mixed solvents thereof. Examples of the chain hydrocarbon solvent include chain alkanes and alkenes having 4 to 6 carbon atoms, such as n-butane, isobutane, 1-butene, isobutylene, trans-2-butene, cis-2-butene, 1-pentene, trans-2-pentene, cis-2-pentene, n-pentane, isopentane, neo-pentane, and n-hexane. Examples of the cyclic hydrocarbon solvent include aromatic compounds such as benzene, toluene, and xylene; alicyclic hydrocarbon compounds such as cyclopentane and cyclohexane; and the like. These solvents may be used alone or in combination of two or more.

[0049] The amount of the solvent used is not particularly limited, but is preferably an amount such that the concentration of the total block copolymer in the solution after the polymerization reaction is 3 to 40% by weight, more preferably 4 to 30% by weight, and even more preferably 5 to 20% by weight.

[0050] In order to control the structure of each polymer block of each block copolymer, a Lewis base compound may be added to the reactive group used in polymerization. Examples of the Lewis base compound include ethers such as tetrahydrofuran, diethyl ether, dioxane, dibutyl ether, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether; tertiary amines such as tetramethylethylenediamine, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxides such as potassium t-amyl oxide and potassium t-butyl oxide; and phosphines such as triphenylphosphine. These Lewis base compounds may be used alone or in combination of two or more.

[0051] The timing of adding the Lewis base compound is not particularly limited, and may be appropriately determined according to the structure of each target block copolymer. For example, it may be added in advance before starting polymerization, or after some polymer blocks are polymerized. Furthermore, it may be added in advance before starting polymerization, and then additionally added after some polymer blocks are polymerized.

[0052] The polymerization reaction temperature is preferably 10 to 150° C., more preferably 30 to 130° C., and further preferably 40 to 90° C., and the polymerization time is preferably within 48 hours, more preferably 0.5 to 10 hours. The polymerization pressure is not particularly limited as long as it is within a pressure range sufficient to maintain the monomer and the solvent in a liquid phase at the polymerization temperature.

[0053] Under the above-mentioned conditions, an aromatic vinyl monomer is polymerized in a solvent using a polymerization initiator to obtain a solution containing an aromatic vinyl polymer having an active end. The aromatic vinyl polymer having an active end thus obtained is the aromatic vinyl polymer block Ar1 of the block copolymer A constituting the block copolymer composition. a Therefore, each polymerization condition including the amount of the aromatic vinyl monomer may be determined depending on the target weight average molecular weight of these polymer blocks.

[0054] Next, a conjugated diene monomer is added to the solution containing the aromatic vinyl polymer having an active end, and the conjugated diene monomer is polymerized to form a conjugated diene polymer chain starting from the active end of the aromatic vinyl polymer, thereby obtaining a solution containing an aromatic vinyl-conjugated diene block copolymer having an active end. The conjugated diene polymer chain formed in this step is the conjugated diene polymer block D of the block copolymer A. a Therefore, each polymerization condition including the amount of the conjugated diene polymer may be determined depending on the target weight average molecular weight and vinyl bond content of these polymer blocks.

[0055] Next, an aromatic vinyl monomer is added to the solution containing the aromatic vinyl-conjugated diene block copolymer having an active terminal to form an aromatic vinyl polymer chain starting from the active terminal, thereby obtaining a solution containing an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active terminal. The aromatic vinyl polymer chain formed in this step is the aromatic vinyl polymer block Ar2 of the block copolymer A. a Therefore, each polymerization condition including the amount of the aromatic vinyl monomer may be determined depending on the target weight average molecular weight, etc.

[0056] Next, a polymerization terminator is added to the solution containing the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active terminals in an amount of 1 molar equivalent or more relative to the active terminals to deactivate all of the active terminals, thereby obtaining a solution containing block copolymer A.

[0057] The polymerization terminator is not particularly limited as long as it can react with an active terminal to deactivate the active terminal and does not react with another active terminal after reacting with one active terminal, but is preferably a compound that does not contain a halogen atom, and particularly preferably a polymerization terminator that generates a metal alkoxide, a metal aryloxide, or a metal hydroxide when reacting with an active terminal. Specific examples of the polymerization terminator include water; monohydric alcohols such as methanol and ethanol; monohydric phenols such as phenol and cresol; and the like.

[0058] The amount of the polymerization terminator used may be determined depending on the ratio to the block copolymer A or block copolymer B, and is not particularly limited as long as it is an amount of 1 molar equivalent or more relative to the active terminal of the polymer.

[0059] Next, the block copolymer A is recovered from the solution containing the block copolymer A. The recovery method may be a conventional method and is not particularly limited. For example, after the reaction is completed, additives such as an antioxidant may be added as necessary, and then the solution may be directly subjected to a drying method or a known solvent method such as steam stripping to recover the block copolymer A.

[0060] When the block copolymer A is recovered as a slurry by steam stripping or the like, it is preferable to dehydrate the slurry using an arbitrary dehydrator such as an extruder-type squeezer, recover the block copolymer A in the form of crumbs, and further dry the obtained crumbs using an arbitrary dryer such as a band dryer or an expansion extrusion dryer.

[0061] The block copolymer B can be produced by the same method as the above-mentioned method for producing the block copolymer A. That is, the block copolymer B is preferably produced by a method in which an aromatic vinyl monomer, a conjugated diene monomer, and an aromatic vinyl monomer are sequentially polymerized in this order to form a polymer block. The polymerization conditions in the production of the block copolymer B are as follows: b , and Ar2 b , and conjugated diene polymer block D b It may be determined depending on the desired weight average molecular weight, etc.

[0062] The block copolymer A and block copolymer B thus obtained can be mixed by a conventional method such as kneading or solution mixing to produce the block copolymer composition of the present invention.

[0063] The block copolymer composition of the present invention can provide a molded product having excellent flexibility, tensile strength, and restoring force, and can be used in various applications by utilizing these properties. For example, the block copolymer composition of the present invention can be used in applications such as molding materials for elastic films, gloves, elastic bands, condoms, various rolls for office equipment and office use, vibration-proof sheets for electrical and electronic equipment, vibration-proof rubber, shock-absorbing sheets, shock-buffering films and sheets, vibration-proof sheets for housing, vibration-proof damper materials, etc., adhesives for adhesive tapes, adhesive sheets, adhesive labels, adhesive layers for surface protective films, and dust rollers, adhesives for sanitary products and bookbinding, and elastic fibers for clothing, sports goods, etc.

[0064] In addition, when the block copolymer composition of the present invention is made into an elastic sheet, a conventionally known molding method such as melt molding or solution molding can be used as a method for molding the sheet without any particular limitation, but melt molding is particularly preferred from the viewpoint of productivity. Among the melt molding methods, extrusion molding (melt extrusion molding) is preferred from the viewpoint of obtaining a smooth sheet with particularly good productivity. The extrudate obtained by extrusion molding may be hot pressed as necessary to mold the sheet.

[0065] The thickness of the sheet is adjusted depending on the application, but for example, when it is used as a sheet for sanitary products such as disposable diapers and sanitary napkins, it is preferably 0.01 to 5 mm, more preferably 0.03 to 3 mm. EXAMPLES

[0066] The present invention will be described below in more detail with reference to examples, but the present invention is not limited to these examples. In the following, "parts" are by weight unless otherwise specified. In addition, various tests and evaluations were performed according to the following methods.

[0067] [Weight average molecular weight of each block copolymer] The weight-average molecular weights of block copolymers A and B were determined in terms of polystyrene equivalent molecular weight by high-performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The apparatus used was a Tosoh HLC8320, the column consisted of three connected Showa Denko Shodex KF-404HQ columns (column temperature 40°C), and the detectors used were a differential refractometer and an ultraviolet detector. The molecular weights were calibrated at 12 points using standard polystyrene (5 to 3 million) manufactured by Tosoh.

[0068] [Weight average molecular weight of styrene polymer block of each block copolymer] According to the method described in Rubber Chem. Technol., 45, 1295 (1972), the block copolymer was reacted with ozone and reduced with lithium aluminum hydride to decompose the isoprene polymer block of the block copolymer. Specifically, the following procedure was followed. That is, 300 mg of the sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. After placing this reaction vessel in a cooling bath and lowering the temperature to -25°C, ozone generated by an ozone generator was introduced into the reaction vessel while oxygen was flowing at a flow rate of 170 ml / min. After 30 minutes had elapsed from the start of the reaction, the completion of the reaction was confirmed by introducing the gas flowing out of the reaction vessel into the potassium iodide aqueous solution. Next, 50 ml of diethyl ether and 470 mg of lithium aluminum hydride were charged into another reaction vessel substituted with nitrogen, and the solution reacted with ozone was slowly dropped into the reaction vessel while cooling the reaction vessel with ice water. The reaction vessel was then placed in a water bath, gradually heated, and refluxed at 40°C for 30 minutes. After that, while stirring the solution, dilute hydrochloric acid was dripped into the reaction vessel in small amounts until hydrogen generation was almost no longer observed. After this reaction, the solid product generated in the solution was filtered, and the solid product was extracted with 100 ml of diethyl ether for 10 minutes. This extract was combined with the filtrate obtained by filtration, and the solvent was distilled off to obtain a solid sample. The weight average molecular weight of the sample thus obtained was measured according to the above-mentioned method for measuring weight average molecular weight, and the value was taken as the weight average molecular weight of the styrene polymer block.

[0069] [Styrene unit content of each block copolymer] Based on the detection intensity ratio between the differential refractometer and the ultraviolet detector in the above-mentioned high performance liquid chromatography measurement, the styrene unit content of block copolymer A and the styrene unit content of block copolymer B were determined. Note that copolymers having different styrene units were prepared in advance, and calibration curves were created using them.

[0070] [Weight ratio of each block copolymer] The weight ratio of each polymer block used when mixing block copolymer A and block copolymer B was defined as the weight ratio (A / B) of block copolymer A to block copolymer B in the block copolymer composition.

[0071] [Content of styrene units in the entire block copolymer composition] The styrene unit content of the entire block copolymer composition was calculated from the styrene unit content of each block copolymer calculated by the above method and the weight ratio (A / B) of block copolymer A to block copolymer B.

[0072] [Sheet tensile strength, elongation at break, stress at 50% elongation, stress at 400% elongation] The sheets obtained in the examples and comparative examples were punched out using a dumbbell-shaped No. 6 punch of JIS K 6251 to prepare dumbbell-shaped test pieces. The obtained test pieces were then measured for stress at 50% elongation, stress at 400% elongation, tensile strength, and elongation at break at a tensile speed of 500 mm / min. The smaller the stress at 50% elongation and 400% elongation, the softer the texture, which is preferable. The higher the tensile strength and elongation at break, the more preferable.

[0073] [Residual set of sheet after 300% elongation (permanent elongation)] The sheet prepared by the above method was measured using a Tensilon universal testing machine RTC-1210 manufactured by ORIENTEC. Specifically, the sheet was stretched at an elongation rate of 300% with a gauge length of 20 mm before stretching, and then contracted without rebounding. After leaving it for 10 minutes, the gauge length was measured and the residual strain was calculated based on the following formula. The smaller the residual strain, the better the restoring force, and therefore it is preferable. Residual strain (%) = (L1-L0) / L0 x 100 L0: Gauge length before stretching (mm) L1: Gauge distance after shrinking and leaving for 10 minutes (mm)

[0074] [Production Example 1] In a pressure-resistant reactor, 90.0 kg of cyclohexane, 3.7 mmol of N,N,N',N'-tetramethylethylenediamine (hereinafter referred to as "TMEDA"), and 1.1 kg of styrene were added, and while stirring at 40°C, 123.5 mmol of n-butyllithium was added, and polymerization was carried out for 1 hour while raising the temperature to 50°C. The polymerization conversion rate of styrene was 100%. Subsequently, 7.8 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature to maintain 50-60°C. After the addition of isoprene was completed, polymerization was carried out for another 1 hour. The polymerization conversion rate of isoprene was 100%. Next, 1.1 kg of styrene was continuously added over 1 hour while controlling the temperature to maintain 50-60°C. After the addition of styrene was completed, polymerization was carried out for another 1 hour to form a triblock chain having an active end. The polymerization conversion rate of styrene was 100%. Next, 247 mmol of methanol was added as a polymerization terminator and mixed to deactivate all the active ends of the triblock chain and terminate the reaction, forming styrene-isoprene-styrene triblock copolymer A. The amounts of each sample used in the reaction are summarized in Table 1. A part of the resulting reaction solution was taken out and the block copolymer A was evaluated according to the above-mentioned measurement method. The results are shown in Table 2. 0.3 parts of 2,6-di-t-butyl-p-cresol was added as an antioxidant to 100 parts of the resulting reaction solution and mixed, and the mixed solution was dropped in small amounts into warm water heated to 85 to 95 ° C., and the solvent was volatilized to obtain a precipitate of block copolymer A.

[0075] [Manufacturing Examples 2-3] Block copolymers B-1 and B-2 were formed and evaluated in the same manner as in Production Example 1, except that the amounts of TMEDA, n-butyllithium, styrene, isoprene, and methanol used were changed to those shown in Table 1. Precipitates of block copolymers B-1 and B-2 were obtained in the same manner as in Production Example 1.

[0076] [Example 1] Block copolymer A-1 and block copolymer B-1 were added to a Banbury mixer in an amount such that the weight ratio of block copolymer A-1 to block copolymer B-1 (A / (B-1)) was 67 / 33, and the mixture was kneaded at 200°C for 3 minutes to obtain a block copolymer composition. The block copolymer composition was added to a biaxial microcompounder and extruded for 5 minutes under conditions of 220°C and 100 rpm in a nitrogen atmosphere. The extrudate was hot pressed three times under conditions of 170°C, 20 MPa, and 20 seconds to produce a sheet with a thickness of 2 mm. The obtained sheet was evaluated for tensile strength, elongation at break, stress at 50% elongation, stress at 400% elongation, and residual strain after 300% elongation by the above-mentioned method. The results are shown in Table 2.

[0077] [Examples 2 to 3, Comparative Examples 1 to 4] Block copolymer compositions and sheets were obtained and evaluated in the same manner as in Example 1, except that the amounts of each block copolymer used were changed to the weight ratios shown in Table 2. The results are shown in Table 2.

[0078] [Table 1]

[0079] [Table 2]

[0080] As shown in Table 2, the molded articles obtained from the block copolymer compositions containing block copolymer A represented by general formula (A) and block copolymer B represented by general formula (B) in a ratio A / B (weight ratio) of 45 / 55 to 90 / 10, and in which the aromatic vinyl monomer unit contents and weight average molecular weights of block copolymer A and block copolymer B were within the specified ranges, had excellent flexibility, tensile strength, and restoring force (Examples 1 to 4).

[0081] On the other hand, when the block copolymer B represented by the general formula (B) was not contained, the tensile strength and restoring force were inferior (Comparative Example 1). When the content ratio of the block copolymer A and the block copolymer B was outside the range of 45 / 55 to 90 / 10 in weight ratio A / B, the flexibility and restoring force were significantly inferior (Comparative Example 2). When the block copolymer A represented by the general formula (A) was not contained, the block copolymer B was resinified, and the evaluation could not be performed (Comparative Example 3). When the block copolymer B-2 having a small weight average molecular weight was used as the block copolymer B, the block copolymer composition was inferior in tensile strength and restoring force (Comparative Example 4).

Claims

1. A block copolymer composition comprising a block copolymer A represented by the following general formula (A) and a block copolymer B represented by the following general formula (B): The content of aromatic vinyl monomer units in the block copolymer (A) is 10 to 30% by weight, The content of aromatic vinyl monomer units in the block copolymer (B) is 40 to 65% by weight, The weight average molecular weight of the block copolymer (A) is 80,000 to 150,000; The weight average molecular weight of the block copolymer (B) is 300,000 to 500,000; The block copolymer composition, wherein the weight ratio (A / B) of the block copolymer A to the block copolymer B is 45 / 55 to 90 / 10. Ar1 ａ -D ａ -Ar2 ａ (A) Ar1 ｂ -D ｂ -Ar2 ｂ (B) (In the general formulas (A) and (B), Ar1 ａ , Ar2 ａ , Ar1 ｂ and Ar2 ｂ are aromatic vinyl polymer blocks, and D ａ and D. ｂ are conjugated diene polymer blocks, and Ar1 ａ Ar2 relative to the weight average molecular weight of ａ The ratio of weight average molecular weights (Mw(Ar2 ａ ) / Mw(Ar1 ａ ) is 0.9 to 1.1, and Ar1 ｂ Ar2 relative to the weight average molecular weight of ｂ The ratio of weight average molecular weights (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ ) is 0.9 to 1.

1.

2. In the general formula (B), Ar1 ｂ and Ar2 ｂ 2. The block copolymer composition according to claim 1, wherein each of the weight average molecular weights of is 80,000 to 150,000.

3. 3. The block copolymer composition according to claim 1, wherein the proportion of aromatic vinyl monomer units in all repeating units of the polymer component of the block copolymer composition is 20 to 44% by weight.

4. 3. The block copolymer composition according to claim 1, wherein, in general formulas (A) and (B), a ratio (Mw(B) / Mw(A)) of the weight average molecular weight (Mw(B)) of the block copolymer (B) to the weight average molecular weight (Mw(A)) of the block copolymer (A) is 3 to 5.

5. In the general formulas (A) and (B), Ar1 ａ Ar1 relative to the weight average molecular weight of ｂ The ratio of weight average molecular weights (Mw(Ar1 ｂ ) / Mw(Ar1 ａ 3. The block copolymer composition according to claim 1, wherein the molar ratio of the block copolymer to the molar ratio of the stoichiometric ratio is 3.0 to 30.

6. A molded article obtained by molding the block copolymer composition according to claim 1 or 2.