Crosslinkable polymer composition, crosslinked product, and crosslinked foam

Abstract

Provided is a crosslinkable polymer composition that contains, at a specific ratio (C / (A+B)): a hydrogenated block copolymer composition containing a hydrogenated block copolymer A represented by general formula (A), and a hydrogenated block copolymer B represented by general formula (B) at a specific weight ratio (A / B), and having an olefin hydrogenation rate of 10-100%; and a polyolefin-based thermoplastic resin C. The crosslinkable polymer composition further contains a crosslinking agent.

Description

Crosslinkable polymer composition, crosslinked product, and crosslinked foam

[0001] The present invention relates to a crosslinkable polymer composition, and more particularly to a crosslinkable polymer composition which has excellent moldability and can give a crosslinked product which has a good balance of high resilience and compression set resistance.

[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 are therefore used in a variety of applications.

[0003] For example, Patent Document 1 discloses a crosslinking and foaming composition comprising (A) an ethylene copolymer, (B) a vinyl aromatic copolymer containing vinyl aromatic monomer units and conjugated diene monomer units having an unsaturated bond, (C) an organic peroxide, and (D) a foaming agent, wherein the mass ratio (A / B) of component (A) to component (B) is 97 / 3 to 50 / 50, and component (B) contains 5% to 80% by mass of the vinyl aromatic monomer units and 5 to 55% by mass of the conjugated diene monomer units. However, the technology of Patent Document 1 was unable to achieve both high resilience and compression set resistance in the resulting crosslinked product.

[0004] International Publication No. 2010 / 073589

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a crosslinkable polymer composition which is excellent in moldability and can give a crosslinked product which has a good balance of high resilience and resistance to compression set.

[0006] The present inventors have conducted studies to achieve the above-mentioned object and have found that the above-mentioned object can be achieved by a crosslinkable polymer composition containing a hydrogenated block copolymer composition having a hydrogenated block copolymer A represented by general formula (A) and a hydrogenated block copolymer B represented by general formula (B) in a specific weight ratio (A / B) and having an olefin hydrogenation rate of 10 to 100%, and a polyolefin-based thermoplastic resin C in a specific ratio (C / (A+B)), and further containing a crosslinking agent, thereby completing the present invention.

[0007] That is, according to the present invention, the following crosslinkable polymer composition is provided.

[0008] [1] A crosslinkable polymer composition comprising a hydrogenated block copolymer composition having a hydrogenated block copolymer A represented by the following general formula (A) and a hydrogenated block copolymer B represented by the following general formula (B), a polyolefin-based thermoplastic resin C, and a crosslinking agent, wherein the hydrogenation rate of olefin in the polymer components constituting the hydrogenated block copolymer composition is 10 to 100%, the weight ratio (A / B) of the hydrogenated block copolymer A to the hydrogenated block copolymer B in the hydrogenated block copolymer composition is 10 / 90 to 80 / 20, and the ratio (C / (A+B)) of the content of the polyolefin-based thermoplastic resin C to the total content of the hydrogenated block copolymer A and the hydrogenated block copolymer B is 5 / 95 to 80 / 20 by weight. ａ -HD ａ -Ar2 ａ (A) Ar1 ｂ -HD ｂ -Ar2 ｂ (B) (In the above general formula (A) and general formula (B), Ar1 ａ , Ar2 ａ , Ar1 ｂ , and Ar2 ｂ is an aromatic vinyl polymer block, and HD ａ and HD ｂ is a hydrogenated polymer block of a conjugated diene polymer, and Ar1 ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar2 ａWeight average molecular weight (Mw(Ar2 ａ )) ratio (Mw(Ar2 ａ ) / Mw(Ar1 ａ )) is 3.0 to 20, and Ar1 ｂ Weight average molecular weight (Mw(Ar1 ｂ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ )) is 0.95 to 1.05.) [2] The crosslinkable polymer composition according to [1], wherein the proportion of aromatic vinyl monomer units in all repeating units of the polymer components of the hydrogenated block copolymer composition is 20 to 70% by weight. [3] The hydrogenated block copolymer composition, ａ and HD ｂ [4] The crosslinkable polymer composition according to [1] or [2], wherein Ar1 in the general formula (A) and the general formula (B) of the hydrogenated block copolymer composition each have a vinyl bond content of 1 to 80 mol %. ａ , Ar1 ｂ , and Ar2 ｂ The weight average molecular weights of the above are in the range of 2,000 to 40,000, and HD ａ and HD ｂThe crosslinkable polymer composition according to any one of [1] to [3], wherein the weight-average molecular weights of the polymer components constituting the hydrogenated block copolymer composition are each in the range of 10,000 to 300,000. [5] The crosslinkable polymer composition according to any one of [1] to [4], wherein the weight-average molecular weight of the entire polymer components constituting the hydrogenated block copolymer composition is 30,000 to 400,000. [6] The crosslinkable polymer composition according to any one of [1] to [5], wherein the polyolefin-based thermoplastic resin C is an ethylene-based resin. [7] The crosslinkable polymer composition according to any one of [1] to [6], wherein the ratio (C / (A+B)) of the content of the polyolefin-based thermoplastic resin C to the total content of the hydrogenated block copolymer A and the hydrogenated block copolymer B is 15 / 85 to 50 / 50 by weight. [8] The crosslinkable polymer composition according to any one of [1] to [7], further comprising a foaming agent. [9] The crosslinkable polymer composition according to [8], wherein the foaming agent is a chemical foaming agent.

[0009] The present invention also provides the following crosslinked product and crosslinked foam.

[10] A crosslinked product obtained by crosslinking the crosslinkable polymer composition according to any one of [1] to [9].

[11] A crosslinked foam obtained by crosslinking and foaming the crosslinkable polymer composition according to any one of [1] to [9].

[12] The crosslinked foam according to

[11] , which is a midsole of a shoe.

[13] The crosslinked foam according to

[11] , which is a cushioning material for a battery.

[14] The crosslinked foam according to

[11] , which is a weatherstrip.

[15] A crosslinked foam having an apparent density of 0.06 to 0.60 g / cm ３

[15] The crosslinked foam according to any one of

[11] to

[14] ,

[0010] According to the present invention, it is possible to provide a crosslinkable polymer composition which is excellent in moldability and can give a crosslinked product which has a good balance of high resilience and resistance to compression set.

[0011] The crosslinkable polymer composition of the present invention contains a hydrogenated block copolymer composition described below, a polyolefin-based thermoplastic resin C, and a crosslinking agent.

[0012] The crosslinkable polymer composition of the present invention has sufficient crosslinkability, and therefore the effects of crosslinking can be fully obtained. Furthermore, it is believed that the crosslinkable polymer composition of the present invention contains, as polymer components, a hydrogenated block copolymer composition having a specific structure and a polyolefin-based thermoplastic resin C in a specific ratio, and therefore the resulting crosslinked product will have excellent strain hardening properties. Such a crosslinkable polymer composition of the present invention can provide a crosslinked product that is excellent in balance between high resilience and compression set resistance.

[0013] In addition, according to the present invention, sufficient crosslinkability and excellent strain hardening can be obtained, thereby suppressing molding defects when molding the crosslinkable polymer composition of the present invention simultaneously with or after crosslinking, and as a result, molding can be performed while applying a large strain (for example, molding at a high stretching ratio or a high expansion ratio). Furthermore, in relation to the production of crosslinked foams, the crosslinkable polymer composition of the present invention effectively suppresses leakage of bubbles from the crosslinkable polymer composition during crosslinking and foaming, so that not only can it be foamed at a high expansion ratio but also crosslinked foams with excellent homogeneity can be obtained. As such, the crosslinkable polymer composition of the present invention can be applied to various molding methods such as stretch molding and foam molding, and has excellent moldability.

[0014] [Hydrogenated Block Copolymer Composition] The hydrogenated block copolymer composition contained in the crosslinkable polymer composition of the present invention has a hydrogenated block copolymer A represented by the following general formula (A) and a hydrogenated block copolymer B represented by the following general formula (B), in which the hydrogenation rate of olefins in the polymer components constituting the hydrogenated block copolymer composition is 10 to 100%, and the weight ratio (A / B) of the hydrogenated block copolymer A to the hydrogenated block copolymer B in the hydrogenated block copolymer composition is 10 / 90 to 80 / 20. ａ -HD ａ -Ar2 ａ (A) Ar1 ｂ -HD ｂ -Ar2 ｂ(B) (In the above general formula (A) and general formula (B), Ar1 ａ , Ar2 ａ , Ar1 ｂ , and Ar2 ｂ is an aromatic vinyl polymer block, and HD ａ and HD ｂ is a hydrogenated polymer block of a conjugated diene polymer, and Ar1 ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar2 ａ Weight average molecular weight (Mw(Ar2 ａ )) ratio (Mw(Ar2 ａ ) / Mw(Ar1 ａ )) is 3.0 to 20, and Ar1 ｂ Weight average molecular weight (Mw(Ar1 ｂ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ )) is 0.95 to 1.05.

[0015] The hydrogenated block copolymer composition used in the present invention is not particularly limited, but it is preferable that the composition contains only hydrogenated block copolymer A and hydrogenated block copolymer B as polymer components.

[0016] Aromatic vinyl polymer block Ar1 of hydrogenated block copolymer A and hydrogenated block copolymer B ａ , Ar2 ａ , Ar1 ｂ , Ar2 ｂ is a polymer block composed of aromatic vinyl monomer units.

[0017] The aromatic vinyl monomer used to form 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; alkyl-substituted styrenes 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; halogen-substituted styrenes such as 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, and 2,4-dibromostyrene; and vinylnaphthalene. Among these, styrene is preferred. These aromatic vinyl monomers can be used alone or in combination of two or more in each aromatic vinyl polymer block. Furthermore, the same aromatic vinyl monomer may be used in each aromatic vinyl polymer block, or different aromatic vinyl monomers may be used. The content of aromatic vinyl monomer units in each aromatic vinyl polymer block is preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably substantially 100% by weight, based on the total weight of the aromatic vinyl polymer block.

[0018] In addition, the aromatic vinyl polymer block Ar1 constituting the hydrogenated block copolymer A and the hydrogenated block copolymer B ａ , Ar2 ａ , Ar1 ｂ , Ar2 ｂ may each contain a monomer unit other than an aromatic vinyl monomer unit. Examples of the monomer constituting the monomer unit other than an aromatic vinyl monomer unit include a conjugated diene monomer such as 1,3-butadiene or isoprene (2-methyl-1,3-butadiene); an α,β-unsaturated nitrile monomer; an unsaturated carboxylic acid or acid anhydride monomer; an unsaturated carboxylic acid ester monomer; and a non-conjugated diene monomer.

[0019] 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 total weight of the aromatic vinyl polymer block.

[0020] Hydrogenated polymer block HD of conjugated diene polymer constituting hydrogenated block copolymer A and hydrogenated block copolymer B ａ , H.D. ｂ is a polymer block constituted by conjugated diene monomer units, and at least a portion of the conjugated diene monomer units constituting the polymer block are hydrogenated.

[0021] The conjugated diene monomer used to form the conjugated diene monomer units is not particularly limited as long as it is a conjugated diene compound. Examples of conjugated diene compounds 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, from the viewpoint of polymerization reactivity, it is preferable to use 1,3-butadiene and / or isoprene, and it is particularly preferable to use isoprene. These conjugated diene monomers can be used alone or in combination of two or more types in each hydrogenated polymer block. Furthermore, the same conjugated diene monomer may be used in each hydrogenated polymer block, or different conjugated diene monomers may be used. The content of the conjugated diene monomer units (including hydrogenated conjugated diene monomer units) in each hydrogenated polymer block is preferably 80% by weight or more, more preferably 90% by weight or more, and particularly preferably substantially 100% by weight, based on the total weight of the conjugated diene polymer block.

[0022] Hydrogenated polymer block HD of conjugated diene polymer constituting hydrogenated block copolymer A and hydrogenated block copolymer B ａ , H.D. ｂmay each contain a monomer unit other than a conjugated diene monomer unit. Examples of the monomer constituting the monomer unit other than a 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.

[0023] The content of monomer units other than conjugated diene monomer units (including hydrogenated conjugated diene monomer units) in each hydrogenated 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 total weight of the conjugated diene polymer block.

[0024] The hydrogenated block copolymer A constituting the hydrogenated block copolymer composition is Ar1 ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar2 ａ Weight average molecular weight (Mw(Ar2 ａ )) ratio (Mw(Ar2 ａ ) / Mw(Ar1 ａ )) is in the range of 3.0 to 20. Therefore, the hydrogenated block copolymer A has an aromatic vinyl polymer block Ar1 having a relatively small weight average molecular weight. ａ , hydrogenated polymer block HD of conjugated diene polymer ａ and an aromatic vinyl polymer block Ar2 having a relatively large weight average molecular weight ａ It is a hydrogenated product of an asymmetric aromatic vinyl-conjugated diene-aromatic vinyl block copolymer composed of these units linked in this order.

[0025] In the hydrogenated block copolymer A, Mw(Ar2 ａ ) / Mw(Ar1 ａ ) is in the range of 3.0 to 20. ａ ) / Mw(Ar1 ａ If Mw(Ar2) is too small or too large, it becomes difficult to achieve both high resilience and compression set resistance in the crosslinked product obtained. ａ ) / Mw(Ar1 ａ) is preferably in the range of 4.0 to 16, more preferably in the range of 5.0 to 13. ａ ) / Mw(Ar1 ａ ) within the above range, moldability can be further improved, and the resulting crosslinked product can achieve both high resilience and compression set resistance at an even higher level. In the present invention, the weight average molecular weight (Mw) and number average molecular weight (Mn) of the polymer or polymer block are determined as polystyrene-equivalent values ​​measured by high performance liquid chromatography.

[0026] The aromatic vinyl polymer block Ar1 having a relatively small weight average molecular weight, which constitutes the hydrogenated block copolymer A, ａ Weight average molecular weight (Mw(Ar1 ａ )) is preferably 2,000 to 40,000, more preferably 2,500 to 15,000, and even more preferably 3,000 to 8,000. ａ ) within the above range, moldability can be further improved, and the mechanical properties can be improved while achieving high resilience and compression set resistance of the obtained crosslinked product at a higher level.

[0027] In addition, the aromatic vinyl polymer block Ar2 having a relatively large weight average molecular weight that constitutes the hydrogenated block copolymer A ａ Weight average molecular weight (Mw(Ar2 ａ )) is preferably 5,000 to 250,000, more preferably 10,000 to 120,000, and even more preferably 20,000 to 80,000. ａ ) within the above range, moldability can be further improved, and the mechanical properties can be improved while achieving high resilience and compression set resistance of the obtained crosslinked product at a higher level.

[0028] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer A ａThe vinyl bond content (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) is preferably 1 to 80 mol %, more preferably 3 to 20 mol %, and even more preferably 5 to 12 mol %. By having the vinyl bond content within the above range, the crosslinked product obtained can achieve both high resilience and compression set resistance at an even higher level. The vinyl bond content of the hydrogenated polymer block of the conjugated diene polymer can be adjusted by using deuterated chloroform as a solvent. １ It can be determined by H-NMR.

[0029] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer A ａ Weight average molecular weight (Mw(HD ａ )) is preferably 10,000 to 300,000, more preferably 15,000 to 300,000, even more preferably 15,000 to 150,000, and particularly preferably 20,000 to 80,000.

[0030] The content of aromatic vinyl monomer units relative to the total monomer units of the hydrogenated block copolymer A is not particularly limited, but is preferably 30 to 95% by weight, more preferably 35 to 90% by weight, even more preferably 40 to 87% by weight, and particularly preferably 45 to 85% by weight. The content of aromatic vinyl monomer units relative to the total monomer units of the hydrogenated block copolymer A can be determined based on the ratio of the detection intensities obtained with a differential refractometer and an ultraviolet detector in high performance liquid chromatography measurements.

[0031] The weight average molecular weight of the hydrogenated block copolymer A as a whole is not particularly limited, but is preferably 20,000 to 500,000, more preferably 25,000 to 300,000, and even more preferably 30,000 to 150,000.

[0032] The hydrogenated block copolymer B constituting the hydrogenated block copolymer composition is a conjugated diene polymer block HD. ｂ At both ends of each of the two aromatic vinyl polymer blocks Ar1 ｂ , Ar2 ｂThe hydrogenated block copolymer B is a hydrogenated product of an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer, which is composed of two aromatic vinyl polymer blocks Ar1 and Ar2. ｂ , Ar2 ｂ Weight average molecular weight (Mw(Ar1 ｂ ), Mw(Ar2 ｂ )) is Ar1 ｂ Weight average molecular weight (Mw(Ar1 ｂ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ ) is 0.95 to 1.05.

[0033] Two aromatic vinyl polymer blocks Ar1 constituting the hydrogenated block copolymer B ｂ , Ar2 ｂ Weight average molecular weight (Mw(Ar1 ｂ ), Mw(Ar2 ｂ )) are each preferably 2,000 to 40,000, more preferably 2,500 to 15,000, and even more preferably 3,000 to 8,000. ｂ ) and Mw(Ar2 ｂ When the ratio of the two aromatic vinyl polymer blocks Ar1 to Ar2 is within the above range, moldability can be further improved, and the obtained crosslinked product can have both high resilience and compression set resistance at a higher level, while also having improved mechanical properties. ｂ , Ar2 ｂ Weight average molecular weight (Mw(Ar1 ｂ ), Mw(Ar2 ｂ )) may be the same as or different from each other, but are preferably substantially the same. ｂ Weight average molecular weight (Mw(Ar1 ｂ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ)) may be in the range of 0.95 to 1.05, and preferably in the range of 0.97 to 1.03.

[0034] In addition, these two aromatic vinyl polymer blocks Ar1 ｂ , Ar2 ｂ At least one polymer block of the ｂ ), Mw(Ar2 ｂ )) is an aromatic vinyl polymer block Ar1 having a relatively small weight average molecular weight that constitutes the hydrogenated block copolymer A. ａ Weight average molecular weight (Mw(Ar1 ａ )) may be equal to or different from Ar1), but it is more preferable that they are substantially equal to each other. ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar1 ｂ Weight average molecular weight (Mw(Ar1 ｂ )) ratio (Mw(Ar1 ｂ ) / Mw(Ar1 ａ )) may be in the range of 0.9 to 2.2, and Ar1 ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ａ )) may be in the range of 0.9 to 2.2. ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar1 ｂ Weight average molecular weight (Mw(Ar1 ｂ )) ratio (Mw(Ar1 ｂ ) / Mw(Ar1 ａ )) is in the range of 0.95 to 1.05, or Ar1 ａ Weight average molecular weight (Mw(Ar1 ａ )) with respect to Ar2 ｂ Weight average molecular weight (Mw(Ar2 ｂ )) ratio (Mw(Ar2 ｂ ) / Mw(Ar1 ａ )) is preferably in the range of 0.95 to 1.05.

[0035] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B ｂ The vinyl bond content (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) is preferably 1 to 80 mol %, more preferably 3 to 20 mol %, and even more preferably 5 to 12 mol %. By having the vinyl bond content within the above range, the crosslinked product obtained can achieve both high resilience and compression set resistance at an even higher level. The vinyl bond content of the hydrogenated polymer block of the conjugated diene polymer can be adjusted by using deuterated chloroform as a solvent. １ The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B can be determined by H-NMR. ｂ The vinyl bond content of the hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer A is ａ For example, the vinyl bond content of the hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer A is preferably substantially equal to ａ The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B with respect to the vinyl bond content of ｂ It is preferable that the ratio of the vinyl bond content of the copolymer to the vinyl bond content of the copolymer is in the range of 0.95 to 1.05.

[0036] In addition, when the hydrogenated block copolymer composition used in the present invention is produced, for example, when a production method using a coupling agent is adopted, such as when a production method for a hydrogenated block copolymer composition having steps (1a) to (6a) described below is adopted, the hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B is ｂ However, Ar1 may contain a residue of a coupling agent. Specifically, the hydrogenated block copolymer B may be a compound represented by the following formula: ｂ - (HD ｂ’ -X-HD ｂ’ ’ ) -Ar2 ｂ That is, as shown in the above formula, the hydrogenated polymer block HD of the conjugated diene polymer ｂis coupled to HD via the residue X of the coupling agent. ｂ’ , H.D. ｂ’ ’ Examples of the residue X of the coupling agent include residues of bifunctional coupling agents exemplified in the method for producing a hydrogenated block copolymer composition having steps (1a) to (6a) described below.

[0037] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B ｂ Weight average molecular weight (Mw(HD ｂ )) is preferably 10,000 to 300,000, more preferably 15,000 to 300,000, even more preferably 15,000 to 150,000, and particularly preferably 20,000 to 80,000.

[0038] The content of aromatic vinyl monomer units relative to the total monomer units of hydrogenated block copolymer B is not particularly limited, but is preferably 10 to 60% by weight, more preferably 15 to 40% by weight, and even more preferably 20 to 35% by weight. The content of aromatic vinyl monomer units relative to the total monomer units of hydrogenated block copolymer A can be determined based on the detection intensity ratio between a differential refractometer and an ultraviolet detector in high performance liquid chromatography measurement.

[0039] The weight average molecular weight of the hydrogenated block copolymer B as a whole is not particularly limited, but is preferably 20,000 to 200,000, more preferably 25,000 to 150,000, and even more preferably 30,000 to 70,000.

[0040] The molecular weight distributions of the hydrogenated block copolymer A and hydrogenated block copolymer B constituting the hydrogenated block copolymer composition used in the present invention, and of each polymer block constituting these copolymers, expressed as the ratio of the weight average molecular weight (Mw) to the number average molecular weight (Mn) [(Mw) / (Mn)], are not particularly limited, but are each preferably 1.1 or less, and more preferably 1.05 or less.

[0041] The weight ratio (A / B) of hydrogenated block copolymer A to hydrogenated block copolymer B contained in the hydrogenated block copolymer composition used in the present invention is 10 / 90 to 80 / 20. If the weight ratio (A / B) is too small or too large, it becomes difficult to achieve both high resilience and compression set resistance in the resulting crosslinked product. The weight ratio (A / B) is preferably 20 / 80 to 60 / 40, more preferably 25 / 75 to 50 / 50. By containing hydrogenated block copolymer A and hydrogenated block copolymer B in such a ratio, moldability can be further improved, and the resulting crosslinked product can achieve both high resilience and compression set resistance at even higher levels. The weight ratio (A / B) of hydrogenated block copolymer A to hydrogenated block copolymer B can be determined from the area ratio of the peaks corresponding to each block copolymer in a chart obtained by high-performance liquid chromatography.

[0042] The hydrogenated block copolymer composition used in the present invention has an olefin hydrogenation rate in the range of 10 to 100% among the polymer components constituting the hydrogenated block copolymer composition. Here, the olefin hydrogenation rate refers to the olefin hydrogenation rate of all polymer components constituting the hydrogenated block copolymer composition, specifically the proportion (mol %) of hydrogenated non-aromatic carbon-carbon double bonds among all non-aromatic carbon-carbon double bonds contained in the polymer components before hydrogenation. If the olefin hydrogenation rate is too low, it becomes difficult to achieve both high resilience and compression set resistance in the resulting crosslinked product. Furthermore, molding defects are likely to occur when molding is performed simultaneously with crosslinking or after crosslinking. The olefin hydrogenation rate is preferably 80 to 100%, more preferably 90 to 100%, and even more preferably 95 to 100%. By keeping the olefin hydrogenation rate within the above range, the effect of crosslinking can be further enhanced, and a crosslinked product having excellent mechanical properties and dimensional stability in addition to high resilience and compression set resistance can be obtained with high moldability and high productivity. The olefin hydrogenation rate can be determined by the use of deuterated chloroform as a solvent. １ It can be determined by H-NMR spectrum measurement.

[0043] In the hydrogenated block copolymer composition used in the present invention, the proportion of aromatic vinyl monomer units relative to the total polymer components in the hydrogenated block copolymer composition (total monomer units constituting the polymer components) (hereinafter sometimes referred to as the "total aromatic vinyl monomer unit content") is preferably 20 to 70% by weight, more preferably 25 to 60% by weight, and even more preferably 30 to 55% by weight. Having the total aromatic vinyl monomer unit content within the above range further enhances moldability, and the resulting crosslinked product can be improved in both high resilience and compression set resistance at even higher levels, while also improving mechanical properties. The total aromatic vinyl monomer unit content can be easily adjusted by taking into account the aromatic vinyl monomer unit contents of hydrogenated block copolymer A, hydrogenated block copolymer B, and other polymer components constituting the hydrogenated block copolymer composition, and adjusting the blending amounts of these components. The total aromatic vinyl monomer unit content can be easily adjusted by adjusting the blending amounts of these components, taking into account the aromatic vinyl monomer unit contents of the hydrogenated block copolymer A, hydrogenated block copolymer B, and other polymer components constituting the hydrogenated block copolymer composition. １ It can be determined by H-NMR measurement.

[0044] In addition, when all polymer components constituting the hydrogenated block copolymer composition are composed only of aromatic vinyl monomer units and conjugated diene monomer units, the polymer components in the hydrogenated block copolymer composition can be decomposed by ozonolysis and then reduced with lithium aluminum hydride according to the method described in Rubber Chem. Technol., 45, 1295 (1972), whereby the conjugated diene monomer unit portions (including hydrogenated portions) can be decomposed and only the aromatic vinyl monomer unit portions can be isolated, thereby easily measuring the total aromatic vinyl monomer unit content. The aromatic vinyl monomer unit content and the conjugated diene monomer unit content in each block copolymer can be determined by the same method.

[0045] The weight-average molecular weight of all the polymer components constituting the hydrogenated block copolymer composition used in the present invention is not particularly limited, but is preferably 30,000 to 400,000, more preferably 35,000 to 100,000, and even more preferably 40,000 to 80,000. When the weight-average molecular weight of all the polymer components is within the above range, moldability can be further improved, and the obtained crosslinked product can have both high resilience and compression set resistance at even higher levels, while also having improved mechanical properties.

[0046] Furthermore, the molecular weight distribution, which is expressed as the ratio (Mw / Mn) of the weight average molecular weight (Mw) to the number average molecular weight (Mn) of all the polymer components constituting the hydrogenated block copolymer composition used in the present invention, is not particularly limited, but is preferably 1 to 5, more preferably 1.01 to 3, and even more preferably 1.02 to 1.5.

[0047] [Method for Producing Hydrogenated Block Copolymer Composition] The method for producing the hydrogenated block copolymer composition used in the present invention is not particularly limited, and the composition can be produced, for example, by separately producing hydrogenated block copolymer A and hydrogenated block copolymer B according to conventional block copolymer production methods and hydrogenation methods, blending other polymer components and various additives as necessary, and then mixing them according to a conventional method such as kneading or solution mixing. On the other hand, in the present invention, the production method described below is preferred from the viewpoint of being able to produce the hydrogenated block copolymer composition with high productivity.

[0048] That is, the method for producing the hydrogenated block copolymer composition used in the present invention is preferably a production method comprising the following steps (1) to (7): (1): A step of polymerizing an aromatic vinyl monomer in a solvent using a polymerization initiator to obtain a solution containing an aromatic vinyl polymer having active ends. (2): A step of adding a conjugated diene monomer to the solution containing the aromatic vinyl polymer having active ends obtained in the step (1) above and polymerizing the conjugated diene monomer to obtain a solution containing an aromatic vinyl-conjugated diene block copolymer having active ends. (3): A step of adding an aromatic vinyl monomer to the solution containing the aromatic vinyl-conjugated diene block copolymer having active ends obtained in the step (2) above and polymerizing the aromatic vinyl monomer to obtain a solution containing an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends. (4): A step of adding a polymerization terminator to the solution containing the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends obtained in the step (3) above in an amount of less than 1 molar equivalent relative to the active ends of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer to deactivate a portion of the active ends of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends to obtain a solution containing block copolymer B'. (5): A step of adding an aromatic vinyl monomer to the solution containing block copolymer B' obtained in the step (4) above to polymerize the aromatic vinyl monomer, thereby obtaining a solution containing block copolymer B' and block copolymer A'. (6): A step of subjecting the solution containing block copolymer B' and block copolymer A' obtained in the step (5) above to a hydrogenation reaction, thereby obtaining a solution containing hydrogenated block copolymer B and hydrogenated block copolymer A. (7): A step of recovering a hydrogenated block copolymer composition from the solution containing hydrogenated block copolymer B and hydrogenated block copolymer A obtained in the step (6) above.

[0049] <Step (1)> In the method for producing this hydrogenated block copolymer composition, first, in step (1), 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.

[0050] The polymerization initiator may be any polymerization initiator known to have anionic polymerization activity for aromatic vinyl monomers and conjugated diene monomers, such as organic alkali metal compounds, organic alkaline earth metal compounds, and organic lanthanoid series rare earth metal compounds.

[0051] 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 ethyllithium, n-propyllithium, isopropyllithium, n-butyllithium, sec-butyllithium, t-butyllithium, hexyllithium, phenyllithium, stilbenelithium, dialkylaminolithium, diphenylaminolithium, and ditrimethylsilylaminolithium; organic dilithium compounds such as methylenedilithium, tetramethylenedilithium, hexamethylenedilithium, isoprenyldilithium, and 1,4-dilithio-ethylcyclohexane; and organic trilithium compounds such as 1,3,5-trilithiobenzene. Among these, organic monolithium compounds are particularly preferably used.

[0052] Examples of 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.

[0053] In addition to the above, a catalyst that forms a homogeneous system in an organic solvent and has living polymerizability, such as a composite catalyst comprising a lanthanoid series rare earth metal compound containing neodymium, samarium, gadolinium, etc. / alkylaluminum / alkylaluminum halide / alkylaluminum hydride, or a metallocene catalyst containing titanium, vanadium, samarium, gadolinium, etc., can also be used.

[0054] The polymerization initiator may be used alone or in combination of two or more. The amount of the polymerization initiator used is not particularly limited and may be determined depending on the molecular weight of the target block copolymer, but is preferably 0.01 to 20 mmol, more preferably 0.05 to 15 mmol, and even more preferably 0.1 to 10 mmol per 100 g of the total monomers used in the polymerization.

[0055] The solvent used in the polymerization is not particularly limited as long as it is inert to the polymerization initiator, and examples thereof include chain hydrocarbon solvents, cyclic hydrocarbon solvents, and mixed solvents thereof. Examples of chain hydrocarbon solvents 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 cyclic hydrocarbon solvents 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.

[0056] 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 5 to 60% by weight, more preferably 10 to 55% by weight, and even more preferably 20 to 50% by weight.

[0057] Furthermore, when producing a hydrogenated block copolymer composition, a Lewis base compound may be added to the reaction system in order to control the structure of each polymer block of each block copolymer. Examples of the Lewis base compound include ethers such as tetrahydrofuran, diethyl ether, dioxane, 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.

[0058] When producing a hydrogenated block copolymer composition, the timing of adding the Lewis base compound is not particularly limited and may be appropriately determined depending on the structure of each target block copolymer. For example, the Lewis base compound may be added in advance before the start of polymerization, or after some of the polymer blocks have been polymerized. Furthermore, the Lewis base compound may be added in advance before the start of polymerization, and then additionally added after some of the polymer blocks have been polymerized.

[0059] The polymerization reaction temperature is preferably 10 to 150° C., more preferably 30 to 130° C., and even more preferably 40 to 90° C. The polymerization time is preferably 48 hours or less, 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 solvent in a liquid phase at the polymerization temperature.

[0060] By polymerizing an aromatic vinyl monomer in a solvent using a polymerization initiator under the above conditions, a solution containing an aromatic vinyl polymer having an active end can be obtained. The aromatic vinyl polymer having an active end obtained in this way in step (1) is a solution containing an aromatic vinyl polymer block Ar1 having a relatively small weight average molecular weight of the hydrogenated block copolymer A constituting the hydrogenated block copolymer composition. ａand aromatic vinyl polymer block Ar1 of hydrogenated block copolymer B ｂ , Ar2 ｂ Either one of (i.e., Ar1 ｂ or Ar2 ｂ Therefore, the polymerization conditions in step (1), including the amount of the aromatic vinyl monomer, may be determined depending on the target weight-average molecular weight of these polymer blocks, etc.

[0061] <Step (2)> Next, in step (2), a conjugated diene monomer is added to the solution containing the aromatic vinyl polymer having active ends obtained in step (1), and the conjugated diene monomer is polymerized to obtain a solution containing an aromatic vinyl-conjugated diene block copolymer having active ends.

[0062] According to the step (2), by adding a conjugated diene monomer to the solution containing the aromatic vinyl polymer having active ends obtained in the step (1), a conjugated diene polymer chain is formed starting from the active ends, thereby obtaining a solution containing an aromatic vinyl-conjugated diene block copolymer having active ends.

[0063] The conjugated diene polymer chain formed in step (2) (the conjugated diene block constituting the aromatic vinyl-conjugated diene block copolymer having an active end obtained in step (2)) is a hydrogenated polymer block HD of the conjugated diene polymer of the hydrogenated block copolymer A. ａ and hydrogenated polymer block HD of the conjugated diene polymer of the hydrogenated block copolymer B ｂ Therefore, the polymerization conditions in step (2), including the amount of the conjugated diene polymer, may be determined depending on the target weight average molecular weight of these polymer blocks, etc. (for example, the polymerization conditions may be determined within the ranges explained in step (1) above).

[0064] <Step (3)> Next, in step (3), an aromatic vinyl monomer is added to the solution containing the aromatic vinyl-conjugated diene block copolymer having an active end obtained in step (2), and the aromatic vinyl monomer is polymerized to obtain a solution containing the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active end.

[0065] According to the step (3), by adding an aromatic vinyl monomer to the solution containing the aromatic vinyl-conjugated diene block copolymer having an active end obtained in the step (2), an aromatic vinyl polymer chain is formed starting from the active end, thereby obtaining a solution containing the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active end.

[0066] The aromatic vinyl polymer chain formed in step (3) (the aromatic vinyl block constituting the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active end obtained in step (3)) is the aromatic vinyl polymer block Ar1 of the hydrogenated block copolymer B. ｂ , Ar2 ｂ One of (i.e., Ar1 ｂ or Ar2 ｂ is a block different from the block formed in step (1), for example, Ar1 ｂ When the compound is formed, Ar2 ｂ Therefore, the polymerization conditions in step (3), including the amount of aromatic vinyl monomer, may be determined depending on the target weight-average molecular weight of the polymer block, etc. (for example, the polymerization conditions may be determined within the ranges explained in step (1) above).

[0067] <Step (4)> Next, in step (4), a polymerization terminator is added to the solution containing the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends obtained in step (3) in an amount of less than 1 molar equivalent relative to the active ends, thereby deactivating a portion of the active ends of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends, thereby obtaining a solution containing block copolymer B'.

[0068] The block copolymer B′ obtained in the step (4) is the block copolymer before hydrogenation for obtaining the hydrogenated block copolymer B.

[0069] 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 containing no halogen atoms, 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.

[0070] The amount of the polymerization terminator used may be determined depending on the ratio of hydrogenated block copolymer A and hydrogenated block copolymer B that constitute the hydrogenated block copolymer composition, and is not particularly limited as long as it is an amount that is less than 1 molar equivalent relative to the active terminals of the polymer. However, the amount of the polymerization terminator used is preferably in the range of 0.18 to 0.91 molar equivalents, and more preferably in the range of 0.35 to 0.80 molar equivalents, relative to the active terminals of the polymer.

[0071] As described above, according to step (4), by adding a polymerization terminator to a solution containing an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having active ends in an amount less than 1 molar equivalent relative to the active ends, the active ends of some of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymers having active ends are deactivated, and the copolymers with deactivated active ends become pre-hydrogenation block copolymer B' for constituting hydrogenated block copolymer B. The remaining portion of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymers having active ends that did not react with the polymerization terminator remains unreacted in the solution while maintaining their active ends.

[0072] <Step (5)> Next, in step (5), an aromatic vinyl monomer is added to the solution containing the block copolymer B' obtained in step (4) above, and the aromatic vinyl monomer is polymerized to obtain a solution containing the block copolymer B' and the block copolymer A'.

[0073] According to step (5), when an aromatic vinyl monomer is added to the solution obtained in step (4), the aromatic vinyl monomer is further polymerized from the aromatic vinyl polymer chain on the side having the active end of the aromatic vinyl-conjugated diene-aromatic vinyl block copolymer having an active end that has remained unreacted with the polymerization terminator, thereby extending the aromatic vinyl polymer chain and producing block copolymer A'. Note that block copolymer A' is an aromatic vinyl-conjugated diene-aromatic vinyl block copolymer obtained by extending the aromatic vinyl polymer chain, and serves as the block copolymer before hydrogenation for producing hydrogenated block copolymer A.

[0074] In this case, in the step (5), the aromatic vinyl polymer chain to be extended is the aromatic vinyl polymer block Ar2 having a relatively large weight average molecular weight of the hydrogenated block copolymer A constituting the hydrogenated block copolymer composition. ａ Therefore, the polymerization conditions in step (5), including the amount of the aromatic vinyl monomer, are set so as to achieve the above-mentioned aromatic vinyl polymer block Ar2. ａThe polymerization conditions may be determined depending on the target weight average molecular weight, etc. (for example, the polymerization conditions may be determined within the ranges explained in the above step (1)).

[0075] <Step (6)> Next, in step (6), the solution containing block copolymer B′ and block copolymer A′ obtained in step (5) is subjected to a hydrogenation reaction to obtain a solution containing hydrogenated block copolymer B and hydrogenated block copolymer A.

[0076] The method for hydrogenating the solution containing the block copolymer B′ and the block copolymer A′ is not particularly limited, but examples thereof include a method in which the solution containing the block copolymer B′ and the block copolymer A′ is brought into contact with hydrogen in the presence of a hydrogenation catalyst.

[0077] The hydrogenation catalyst is not particularly limited, but examples thereof include supported heterogeneous catalysts in which a metal such as Ni, Pt, Pd, or Ru is supported on a carrier such as carbon, silica, alumina, or diatomaceous earth; Ziegler-type catalysts that use an organic salt or acetylacetone salt of Ni, Co, Fe, Cr, or the like and a reducing agent such as organoaluminum; organic complex catalysts such as organometallic compounds of Ru, Rh, etc.; and homogeneous catalysts that use a titanocene compound and a reducing agent such as organolithium, organoaluminum, or organomagnesium; among these, Ziegler-type catalysts are preferred.

[0078] The hydrogenation reaction can be carried out according to the methods disclosed in, for example, Japanese Patent Publication Nos. 42-8704, 43-6636, Japanese Patent Laid-Open Nos. 59-133203 and 60-220147.

[0079] The conditions for the hydrogenation reaction may be selected depending on the hydrogenation rate of the olefin in the polymer components constituting the hydrogenated block copolymer composition, and the hydrogenation reaction temperature is preferably 0 to 200°C, more preferably 30 to 150°C. The hydrogen pressure used in the hydrogenation reaction is preferably 0.1 to 15 MPa, more preferably 0.2 to 10 MPa, and even more preferably 0.3 to 5 MPa, and the hydrogenation reaction time is preferably 3 minutes to 10 hours, more preferably 10 minutes to 5 hours. The hydrogenation reaction may be carried out by a batch process, a continuous process, or a combination thereof.

[0080] <Step (7)> ​​Next, in step (7), the target hydrogenated block copolymer composition is recovered from the solution containing the hydrogenated block copolymer B and the hydrogenated block copolymer A obtained in step (6).

[0081] The recovery method may be a conventional method and is not particularly limited. For example, after the reaction is completed, if necessary, a polymerization terminator is added to deactivate the active ends of the polymer having active ends, and if necessary, an additive such as an antioxidant is added, and then the solution is subjected to a known solvent method such as direct drying or steam stripping, thereby recovering the target hydrogenated block copolymer composition. In this case, the polymerization terminator may be any of those described above.

[0082] When the hydrogenated block copolymer composition is recovered as a slurry by steam stripping or the like, it is preferable to dehydrate it using an arbitrary dehydrator such as an extruder-type squeezer to recover the hydrogenated block copolymer composition in the form of crumbs, and then dry the obtained crumbs using an arbitrary dryer such as a band dryer or an expansion extrusion dryer. The hydrogenated block copolymer composition thus obtained may be processed into pellets or the like according to a conventional method before use.

[0083] The solid (pellet-like, crumb-like, etc.) hydrogenated block copolymer composition thus obtained is preferably used after reducing the water content contained in the solid hydrogenated block copolymer composition using a dryer such as a hopper dryer, a hot air circulation tray dryer, a tray vacuum dryer, an agitation vacuum dryer, etc. The drying conditions are not particularly limited as long as the target water content can be achieved, and may be set depending on the amount of water to be reduced and the type of dryer, etc., but are usually set at a drying temperature of 40 to 90°C for a drying time of 1 to 24 hours.

[0084] According to the above-described method for producing a hydrogenated block copolymer composition, hydrogenated block copolymer A and hydrogenated block copolymer B can be continuously produced in the same reaction vessel, and therefore the target hydrogenated block copolymer composition can be produced with superior productivity compared to the case where each hydrogenated block copolymer is produced separately and then mixed.

[0085] In addition to the above-described preferred production method (a production method comprising steps (1) to (7)), when producing the hydrogenated block copolymer composition of the present invention, a production method for a hydrogenated block copolymer composition comprising the following steps (1a) to (6a) is also preferably used. (1a): A step of polymerizing an aromatic vinyl monomer in a solvent using a polymerization initiator to obtain a solution containing an aromatic vinyl polymer having an active terminal. (2a): A step of adding a conjugated diene monomer to the solution containing the aromatic vinyl polymer having an active terminal obtained in the above step (1a) and polymerizing the conjugated diene monomer to obtain a solution containing an aromatic vinyl-conjugated diene block copolymer having an active terminal. (3a): A step of adding a bifunctional coupling agent to the solution containing the aromatic vinyl-conjugated diene block copolymer having an active terminal obtained in the above step (2a) in an amount such that the total number of functional groups relative to the active terminals is less than 1 molar equivalent, thereby coupling a part of the aromatic vinyl-conjugated diene block copolymer having an active terminal to obtain a solution containing block copolymer B'. (4a): A step of adding an aromatic vinyl monomer to the solution containing block copolymer B' obtained in the above step (3a) and polymerizing the aromatic vinyl monomer to obtain a solution containing block copolymer B' and block copolymer A'. (5a): A step of subjecting the solution containing block copolymer B' and block copolymer A' obtained in the step (4a) above to a hydrogenation reaction to obtain a solution containing hydrogenated block copolymer B and hydrogenated block copolymer A. (6a): A step of recovering a hydrogenated block copolymer composition from the solution containing hydrogenated block copolymer B and hydrogenated block copolymer A obtained in the step (5a) above.

[0086] <Step (1a) and Step (2a)> Step (1a) and step (2a) are similar to the above-described step (1) and step (2), and similar conditions can be employed.

[0087] <Step (3a)> In step (3a), a bifunctional coupling agent is added to the solution containing the aromatic vinyl-conjugated diene block copolymer having active ends obtained in step (2a) in an amount such that the total amount of functional groups relative to the active ends is less than 1 molar equivalent, and a part of the aromatic vinyl-conjugated diene block copolymer having active ends is coupled to obtain a solution containing block copolymer B'.

[0088] The block copolymer B′ obtained in the step (3a) is the block copolymer before hydrogenation for obtaining the hydrogenated block copolymer B.

[0089] The bifunctional coupling agent is not particularly limited as long as it has two functional groups that react with the active terminal, and examples thereof include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional halogenated alkanes such as dichloroethane, dibromoethane, methylene chloride, and dibromomethane; and bifunctional tin halides such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, and dibutyldichlorotin.

[0090] The amount of the bifunctional coupling agent used may be determined depending on the ratio of hydrogenated block copolymer A to hydrogenated block copolymer B that constitute the hydrogenated block copolymer composition.

[0091] As described above, according to step (3a), by adding a bifunctional coupling agent to a solution containing an aromatic vinyl-conjugated diene block copolymer having active ends in an amount such that the total amount of functional groups relative to the active ends is less than 1 molar equivalent, a portion of the aromatic vinyl-conjugated diene block copolymer having active ends is coupled to form block copolymer B' before hydrogenation, which is used to form hydrogenated block copolymer B. The remaining portion of the aromatic vinyl-conjugated diene block copolymer having active ends that did not react with the bifunctional coupling agent remains unreacted in the solution, maintaining its active ends.

[0092] <Step (4a)> Next, in step (4a), an aromatic vinyl monomer is added to the solution containing the block copolymer B' obtained in step (3a) above, and the aromatic vinyl monomer is polymerized to obtain a solution containing the block copolymer B' and the block copolymer A'.

[0093] According to step (4a), when an aromatic vinyl monomer is added to the solution obtained in step (3a), the aromatic vinyl monomer is polymerized from the active end of the aromatic vinyl-conjugated diene block copolymer having an active end that remains unreacted with the bifunctional coupling agent, thereby forming an aromatic vinyl polymer chain, thereby obtaining block copolymer A'. Note that block copolymer A' is the block copolymer before hydrogenation for obtaining hydrogenated block copolymer A.

[0094] At this time, the aromatic vinyl polymer chain formed in step (4a) is an aromatic vinyl polymer block Ar2 having a relatively large weight average molecular weight of the hydrogenated block copolymer A constituting the hydrogenated block copolymer composition. ａ Therefore, the polymerization conditions in step (4a), including the amount of the aromatic vinyl monomer, are determined so as to achieve the above-mentioned aromatic vinyl polymer block Ar2. ａ The polymerization conditions may be determined depending on the target weight average molecular weight, etc. (for example, the polymerization conditions may be determined within the ranges explained in the above step (1)).

[0095] <Steps (5a) and (6a)> Then, the solution containing block copolymer B' and block copolymer A' obtained in step (4a) can be used to obtain the hydrogenated block copolymer composition used in the present invention through the operations in steps (5a) and (6a) described above. Note that steps (5a) and (6a) described above are similar to steps (6) and (7) described above, and similar conditions can be used for these steps.

[0096] [Polyolefin-Based Thermoplastic Resin C] The crosslinkable polymer composition of the present invention contains a polyolefin-based thermoplastic resin C in addition to the above-mentioned hydrogenated block copolymer composition.

[0097] The polyolefin-based thermoplastic resin C used in the present invention is not particularly limited as long as it is a thermoplastic resin having an olefin as the main repeating unit, and may be any of an α-olefin homopolymer, a copolymer of two or more α-olefins, and a copolymer of an α-olefin and a monomer other than an α-olefin, or a modified (co)polymer of these. The polyolefin-based thermoplastic resin C preferably has an aromatic vinyl polymer unit content of 10% by mass or less, more preferably 1% by mass or less (substantially no aromatic vinyl polymer unit). The polyolefin-based thermoplastic resin C preferably has an α-olefin unit content of 50% by mass or more, more preferably 70% by mass or more, and even more preferably 80% by mass or more.

[0098] The polyolefin-based thermoplastic resin C used in the present invention may be a homopolymer or copolymer of an α-olefin such as ethylene or propylene, for example, an α-olefin homopolymer such as polyethylene such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), or metallocene polyethylene, polypropylene, metallocene polypropylene, polymethylpentene, or polybutene; a copolymer of ethylene with another α-olefin, for example, an ethylene-propylene random copolymer, an ethylene-propylene block copolymer, an ethylene-butene-1 copolymer, an ethylene-propylene-butene-1 copolymer, or an ethylene-cyclic olefin copolymer; a copolymer of an α-olefin and a vinyl ester, mainly composed of an α-olefin, or a saponified product thereof, for example, an ethylene-vinyl acetate copolymer; Examples of suitable polyolefin thermoplastic resins include ethylene-vinyl alcohol copolymers (EVA), ethylene-vinyl alcohol copolymers, copolymers of α-olefins primarily composed of α-olefins and α,β-unsaturated carboxylic acid esters or α,β-unsaturated carboxylic acids, such as ethylene-α,β-unsaturated carboxylic acid ester copolymers (ethylene-ethyl acrylate copolymer, ethylene-methyl methacrylate copolymer, etc.), ethylene-α,β-unsaturated carboxylic acid copolymers (ethylene-acrylic acid copolymer, ethylene-methacrylic acid copolymer, etc.), acid-modified olefin resins obtained by modifying α-olefin (co)polymers such as polyethylene or polypropylene with unsaturated carboxylic acids and / or anhydrides thereof, such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid, ionomer resins obtained by reacting ethylene and methacrylic acid copolymers with sodium ions, zinc ions, or the like, and mixtures thereof. The polyolefin thermoplastic resin C may be used singly or in combination of two or more.

[0099] Among these, ethylene-based resins (polyethylene or copolymers containing ethylene units as the main component) are preferred, with polyethylene; copolymers of ethylene and vinyl esters mainly composed of ethylene units and saponified products thereof being more preferred, with linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), ethylene-vinyl acetate copolymer (EVA), and ethylene-vinyl alcohol copolymers being even more preferred, with low-density polyethylene (LDPE) and ethylene-vinyl acetate copolymer (EVA) being particularly preferred. Ethylene-based resins preferably have an ethylene unit content of 50% by weight or more, more preferably 70% by weight or more, and even more preferably 80% by weight or more. By using the above-mentioned ethylene-based resins as the polyolefin-based thermoplastic resin C, the effect of crosslinking can be further enhanced, and a crosslinked product having excellent mechanical properties and dimensional stability in addition to high resilience and compression set resistance can be obtained with high moldability and high productivity.

[0100] The density of the polyolefin thermoplastic resin C is usually 0.80 to 0.97 g / cm ３ is selected in the range of 0.85 to 0.96 g / cm ３ more preferably in the range of 0.88 to 0.95 g / cm ３ is selected within the range.

[0101] In the crosslinkable polymer composition of the present invention, the ratio (C / (A+B)) of the content of polyolefin thermoplastic resin C to the total content of hydrogenated block copolymer A and hydrogenated block copolymer B is 5 / 95 to 80 / 20 by weight. If the ratio (C / (A+B)) is too small or too large, it becomes difficult to achieve both high resilience and compression set resistance in the resulting crosslinked product. Furthermore, if the ratio (C / (A+B)) is too small, it becomes difficult to achieve both high resilience and compression set resistance in the resulting crosslinked product. Furthermore, molding defects are likely to occur when molding is performed simultaneously with crosslinking or after crosslinking. The ratio (C / (A+B)) is preferably 10 / 90 to 70 / 30, more preferably 12 / 88 to 60 / 40, and even more preferably 15 / 85 to 50 / 50. When the ratio (C / (A+B)) is within the above range, the effect of crosslinking can be further enhanced, and a crosslinked product having excellent mechanical properties and dimensional stability in addition to high resilience and compression set resistance can be obtained with high moldability and high productivity.

[0102] [Crosslinking Agent] The crosslinkable polymer composition of the present invention contains a crosslinking agent in addition to the hydrogenated block copolymer composition and the polyolefin-based thermoplastic resin C.

[0103] Examples of the crosslinking agent include chemical crosslinking agents such as peroxide-based crosslinking agents and sulfur-based crosslinking agents, and photocrosslinking agents. The crosslinking agents may be used alone or in combination of two or more.

[0104] Examples of peroxide-based crosslinking agents include organic peroxide-based crosslinking agents such as t-butyl hydroperoxide, cumene hydroperoxide, dicumyl peroxide, di-t-butyl peroxide, t-butylcumyl peroxide, 2,5-dimethyl-t-butylperoxyhexane, 2,5-dimethyl-t-butylperoxyhexyne, 1,3-bis(t-butylperoxyisopropyl)benzene, p-chlorobenzoyl peroxide, t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, t-butylbenzoate, and 1,1-bis(t-butylperoxy)-3,3,5-trimethylcyclohexane.

[0105] When a peroxide-based crosslinking agent is used, a polyfunctional unsaturated compound such as tortrolpropane trimethacrylate, divinylbenzene, ethylene dimethacrylate, polyethylene glycol dimethacrylate, triallyl isocyanurate, triallyl cyanurate, diallyl phthalate, diaryl itaconate, or triallyl trimellitate may be used as a crosslinking aid.

[0106] Examples of sulfur-based crosslinking agents include sulfur such as powdered sulfur, sulfur flowers, precipitated sulfur, colloidal sulfur, surface-treated sulfur, and insoluble sulfur; sulfur compounds such as sulfur chloride, sulfur dichloride, morpholine disulfide, alkylphenol disulfide, N,N'-dithiobis(hexahydro-2H-azepinone-2), phosphorus-containing polysulfide, and polymeric polysulfides; and further, tetramethylthiuram disulfide, selenium dimethyldithiocarbamate, and 2-(4'-morpholinodithio)benzothiazole. When a sulfur-based crosslinking agent is used, sulfur vulcanization accelerators such as stearic acid, guanidine-based, aldehyde-amine-based, aldehyde-ammonia-based, thiazole-based, sulfenamide-based, thiourea-based, and xanthate-based sulfur vulcanization accelerators may be used in addition to these sulfur-based crosslinking agents.

[0107] The photocrosslinking agent may be any single compound or combination of compounds that responds to light, such as ultraviolet (UV) light, to generate free radicals that initiate the polymerization of one or more monomers without excessive termination. Known photocrosslinking agents include free radical photoinitiators such as quinones, benzophenones, benzoin ethers, allyl ketones, peroxides, biimidazoles, benzil dimethyl ketals, hydroxyalkylphenyl acetophones, dialkoxyactophenones, trimethylbenzoylphosphine oxide derivatives such as bis(2,4,6-trimethylbenzoyl)phenylphosphine oxide, aminoketones, benzoylcyclohexanols, methylthiophenylmorpholinoketones, morpholinophenylaminoketones, alpha-halogenoacetophenones, oxysulfonylketones, sulfonylketones, benzoyloxime esters, thioxanthrones such as 2-isopropylthioxanthone, camphorquinones, ketocoumarins, and Michler's ketone. Alternatively, the photocrosslinking agent may be a mixture of compounds, one of which provides free radicals when induced by a radiation-activated sensitizer. The photocrosslinking agent is preferably sensitive to visible or ultraviolet (actinic) radiation. The photocrosslinking agent may also be a combination of the above-mentioned polyfunctional unsaturated compound with a free radical photoinitiator.

[0108] The crosslinking agent used in the present invention is not limited to the above-mentioned crosslinking agents, and may be any agent that is sensitive to active energy rays such as electron beams or radioactive rays and is capable of crosslinking the crosslinkable polymer composition of the present invention.

[0109] The crosslinking agent used in the present invention is not particularly limited, but is preferably an organic peroxide crosslinking agent, and more preferably dicumyl peroxide.

[0110] The content of the crosslinking agent is preferably within the range of 0.01 to 20 parts by mass, more preferably within the range of 0.1 to 10 parts by mass, and even more preferably within the range of 0.5 to 5 parts by mass, relative to 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin-based thermoplastic resin C in the crosslinkable polymer composition of the present invention. By having the content of the crosslinking agent within the above range, the effect of crosslinking can be further enhanced, and a crosslinked product having excellent mechanical properties and dimensional stability in addition to high resilience and compression set resistance can be obtained with high moldability and high productivity.

[0111] [Other Components] The crosslinkable polymer composition of the present invention may further contain, as necessary, an antioxidant, zinc oxide, a foaming agent, a foaming assistant, a filler, a tackifying resin, a softener, an antibacterial agent, a light stabilizer, an ultraviolet absorber, a dye, a lubricant, etc.

[0112] The crosslinkable polymer composition of the present invention may contain an antioxidant, if necessary. The type of antioxidant is not particularly limited, and examples that can be used 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 antioxidants may be used alone or in combination of two or more.

[0113] The content of the antioxidant is not particularly limited, but is usually 10 parts by weight or less, and preferably 0.5 to 5 parts by weight, relative to 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin-based thermoplastic resin C in the crosslinkable polymer composition of the present invention. In addition, the timing of blending the antioxidant into the crosslinkable polymer composition is not particularly limited. For example, the antioxidant may be added in advance to the hydrogenated block copolymer composition used to constitute the crosslinkable polymer composition, or may be added when the hydrogenated block copolymer composition and the polyolefin-based thermoplastic resin C are mixed.

[0114] The crosslinkable polymer composition of the present invention may contain zinc oxide, if necessary. The content of zinc oxide is not particularly limited, but is usually 10 parts by weight or less, and preferably 0.5 to 5 parts by weight, per 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin-based thermoplastic resin C in the crosslinkable polymer composition of the present invention.

[0115] When the crosslinkable polymer composition of the present invention is used to produce a crosslinked foam, the crosslinkable polymer composition of the present invention may contain a foaming agent, if necessary. The type of foaming agent is not particularly limited, and examples thereof include chemical foaming agents such as thermal decomposition type foaming agents and reactive type foaming agents; physical foaming agents; etc. The foaming agents may be used alone or in combination of two or more.

[0116] Examples of the thermally decomposable foaming agent include organic thermally decomposable foaming agents such as azo compounds, nitroso compounds, hydrazine derivatives, semicarbazide compounds, tetrazole compounds, and organic acids; and inorganic thermally decomposable foaming agents such as bicarbonates, carbonates, organic acid salts, and nitrites.

[0117] More specifically, examples of azo compounds include azodicarbonamide (ADCA), azobisisobutyronitrile (AIBN), barium azodicarboxylate, and diazoaminobenzene. Examples of nitroso compounds include dinitrosopentamethylenetetramine (DPT). Examples of hydrazine derivatives include p,p'-oxybis(benzenesulfonylhydrazide) (OBSH), paratoluenesulfonylhydrazide (TSH), and hydrazodicarbonamide (HDCA). Examples of semicarbazide compounds include p-toluenesulfonylsemicarbazide. Examples of tetrazole compounds include 5-phenyltetrazole and 1,4-bistetrazole. Examples of organic acids include polycarboxylic acids such as citric acid, oxalic acid, fumaric acid, phthalic acid, malic acid, and tartaric acid.

[0118] Examples of reactive foaming agents include a combination of an isocyanate compound and water, a combination of sodium bicarbonate and acid, a combination of hydrogen peroxide and yeast, and a combination of zinc powder and acid.

[0119] Examples of physical foaming agents include gases such as chlorofluorocarbons and carbon dioxide; volatile liquids such as water and volatile hydrocarbon compounds; and thermally expandable microcapsules encapsulating these gases, volatile liquids, etc.

[0120] Among these, from the viewpoint of achieving a high expansion ratio, chemical foaming agents are preferred, thermal decomposition type foaming agents are more preferred, azo compounds are even more preferred, and azodicarbonamide (ADCA) is particularly preferred.

[0121] The content of the blowing agent may be determined depending on the target expansion ratio and the like, and is not particularly limited. However, it is preferably in the range of 0.1 to 20 parts by mass, more preferably in the range of 0.2 to 10 parts by mass, and even more preferably in the range of 0.5 to 5 parts by mass, relative to 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin thermoplastic resin C in the crosslinkable polymer composition of the present invention.

[0122] The crosslinkable polymer composition of the present invention can be foamed at a high expansion ratio because leakage of bubbles from the crosslinkable polymer composition during crosslinking and foaming is effectively suppressed. Therefore, by blending the above-mentioned suitable foaming agent in the above-mentioned suitable amount, it is possible to foam the crosslinkable polymer composition at a high expansion ratio while effectively suppressing leakage of bubbles from the crosslinkable polymer composition.

[0123] When a foaming agent is used, it is preferable to further use a foaming aid such as urea. The content of the foaming aid is not particularly limited, but is preferably 10 to 300 parts by weight, more preferably 20 to 100 parts by weight, relative to 100 parts by weight of the crosslinking agent in the crosslinkable polymer composition of the present invention. The content of the foaming aid is also not particularly limited, but is preferably 10 to 300 parts by weight, more preferably 20 to 100 parts by weight, relative to 100 parts by weight of the foaming agent in the crosslinkable polymer composition of the present invention.

[0124] The crosslinkable polymer composition of the present invention may contain a filler, if necessary. The type of filler is not particularly limited, and examples thereof include clay, titanium oxide, silicon oxide, talc, calcium carbonate, carbon black, etc. The filler may be used alone or in combination of two or more.

[0125] The content of the filler is not particularly limited, but is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, and even more preferably 5 parts by weight or less, relative to 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin-based thermoplastic resin C in the crosslinkable polymer composition of the present invention.

[0126] The crosslinkable polymer composition of the present invention may contain polymer components other than the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin thermoplastic resin C, as long as the effects of the present invention are not impaired.

[0127] Examples of polymer components other than the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin-based thermoplastic resin C that may be contained in the crosslinkable polymer composition of the present invention include aromatic vinyl-conjugated diene-aromatic vinyl block copolymers other than the hydrogenated block copolymer A and the hydrogenated 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 polyvinyl chloride, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, and polyphenylene ether; and the like.

[0128] In the crosslinkable polymer composition of the present invention, the content of polymer components other than the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin thermoplastic resin C is preferably 20 parts by weight or less, more preferably 10 parts by weight or less, even more preferably 5 parts by weight, particularly preferably 1 part by weight or less, and most preferably substantially 0 part by weight, relative to 100 parts by mass of the total content (A+B+C) of the hydrogenated block copolymer A, the hydrogenated block copolymer B, and the polyolefin thermoplastic resin C in the crosslinkable polymer composition of the present invention.

[0129] [Crosslinkable Polymer Composition] The shape of the crosslinkable polymer composition of the present invention is not particularly limited, and it can be molded into any desired shape, such as pellets, sheets, strands, chips, etc.

[0130] The crosslinkable polymer composition of the present invention can be produced, for example, by a method of mixing a block copolymer composition, a polyolefin-based thermoplastic resin C, a crosslinking agent, and various additives used as needed.

[0131] The method for mixing these components is not particularly limited, and examples thereof include a method in which each component is heated and melted and mixed using a kneading device such as a roll, a Banbury mixer, a kneader, a Labo Plastomill, a single-screw extruder, or a twin-screw extruder, and a method in which each component is dissolved in a solvent and mixed uniformly, and then the solvent is removed by heating or the like. Among these, the heated and melted mixing method is preferred from the viewpoint of more efficient mixing. The temperature during the heated and melted mixing is preferably within a temperature range that can suppress excessive decomposition of each component and the progression of unexpected crosslinking reactions, for example, 90 to 150°C is preferred, and 100 to 130°C is more preferred.

[0132] [Crosslinked Product] The crosslinked product of the present invention can be obtained by crosslinking the crosslinkable polymer composition of the present invention. The crosslinked product of the present invention has a good balance of high resilience and compression set resistance.

[0133] The method for crosslinking the crosslinkable polymer composition is not particularly limited, and known methods can be used depending on the type of crosslinking agent, the desired shape of the crosslinked product, etc. For example, in the case of a chemical crosslinking system, the crosslinkable polymer composition can be crosslinked by heating. The heating temperature in this case is preferably, for example, 130 to 250°C, more preferably 140 to 200°C, and the heating time is preferably, for example, 1 minute to 60 minutes.

[0134] The crosslinked product of the present invention is obtained by crosslinking the crosslinkable polymer composition of the present invention, and therefore contains the above-mentioned hydrogenated block copolymer A, hydrogenated block copolymer B, and polyolefin-based thermoplastic resin C. The content ratios of these components in the crosslinked product are the same as the content ratios of these components in the crosslinkable polymer composition, and the preferred ranges are also the same.

[0135] The crosslinked product of the present invention is usually a product (crosslinked molded product) obtained by crosslinking the crosslinkable polymer composition of the present invention and then molding it. The timing of crosslinking and molding may be simultaneous or different.

[0136] [Crosslinked Foam] The crosslinked product of the present invention may be a crosslinked foam obtained by crosslinking and foaming the crosslinkable polymer composition of the present invention. The present invention also relates to such a crosslinked foam.

[0137] The crosslinked foam of the present invention is excellent in a well-balanced manner in high resilience and compression set resistance. Furthermore, the crosslinkable polymer composition of the present invention effectively prevents bubbles from leaking out of the crosslinkable polymer composition during crosslinking and foaming, allowing foaming at a high expansion ratio, thereby enabling the crosslinked foam of the present invention to have a low apparent density and also to provide a crosslinked foam with excellent homogeneity.

[0138] The method for producing the crosslinked foam of the present invention is not particularly limited, but examples thereof include a method in which the crosslinkable polymer composition of the present invention containing a chemical foaming agent is used, and the composition is heated and compressed while being inserted into a mold to crosslink the composition and decompose the foaming agent, and then the mold is opened to foam the composition. Such a production method makes it possible to foam the composition at a high expansion ratio.

[0139] The conditions for the heat compression are not particularly limited, but the heat compression temperature is usually 130 to 250°C, preferably 140 to 200°C, the heat compression pressure is usually 1 to 30 MPa, preferably 3 to 20 MPa, and the heat compression time is usually 1 to 90 minutes, preferably 5 to 30 minutes.

[0140] The method for producing the crosslinked foam of the present invention may also include a method in which the crosslinkable polymer composition of the present invention is foamed by a known method, followed by crosslinking by a known method, for example, by mixing the crosslinkable polymer composition of the present invention with a physical foaming agent, and then converting the physical foaming agent dissolved or dispersed in the crosslinkable polymer composition of the present invention into a gas phase to foam the resulting mixture, and then crosslinking the resulting mixture.

[0141] The physical blowing agent is a liquefied gas or a supercritical fluid, which is converted into a gas phase by reducing pressure or heating. Examples of the physical blowing agent include aliphatic hydrocarbons such as butane, alicyclic hydrocarbons such as cyclobutane, and inorganic gases such as carbon dioxide, nitrogen, and air. Among these, supercritical fluids are preferred, with supercritical fluids of carbon dioxide and nitrogen being more preferred, and supercritical fluid of nitrogen being even more preferred.

[0142] Examples of the foaming method include an injection molding foaming method. Specifically, the thermoplastic component of the crosslinkable polymer composition is plasticized in a cylinder, and a physical foaming agent is injected into the cylinder to dissolve or disperse the physical foaming agent in the plasticized component, and the resulting mixture is then injected into a mold. After or simultaneously with the injection, the physical foaming agent in the mixture is converted into a gas phase, thereby foaming the mixture.

[0143] Examples of injection molding foaming methods that convert the physical blowing agent in the mixture into a gas phase after or simultaneously with injection include the short shot method, the full shot method, and the core-back method. Among these, the core-back method is preferred from the viewpoint of generating bubbles uniformly in the foam. The core-back method is a method in which a mold capable of expanding its cavity volume is used, and the cavity volume of the mold is expanded after or simultaneously with injection molding, thereby converting the physical blowing agent into a gas phase.

[0144] As the foaming method, instead of an injection molding machine, a method using various other melt molding machines such as an extrusion molding machine can also be adopted. From the viewpoint of further increasing the expansion ratio (i.e., further reducing the apparent density of the crosslinked foam), after foaming the mixture, the foamed mixture may be heated again to further promote foaming.

[0145] As the crosslinking method, the various crosslinking methods described above can also be employed.

[0146] The apparent density of the crosslinked foam of the present invention is not particularly limited, but is preferably 0.06 to 0.60 g / cm ３ is preferably 0.10 to 0.55 g / cm ３ More preferably, it is 0.12 to 0.50 g / cm ３ The crosslinked foam of the present invention is obtained by using the crosslinkable polymer composition of the present invention, and therefore, when the expansion ratio is high (in other words, when the apparent density of the obtained crosslinked foam is low, for example, 0.22 g / cm ３ Even if the above condition is met, the toner has a good balance of high resilience and compression set resistance, and also has excellent homogeneity.

[0147] [Other Crosslinked Molded Articles] The crosslinked product of the present invention is not limited to the above-mentioned crosslinked foam, and may be, for example, a crosslinked molded article obtained by crosslinking the crosslinkable polymer composition of the present invention and molding it into any shape such as a fiber, a film, a tube, etc. The method for producing the crosslinked molded article is not particularly limited, and may be, for example, a method in which the crosslinkable polymer composition of the present invention is molded and then crosslinked, or a method in which a preformed article obtained by preforming the crosslinkable polymer composition of the present invention is crosslinked and then molded.

[0148] As described above, by using the crosslinkable polymer composition of the present invention, it is possible to mold a crosslinked molded article while applying a large strain (e.g., molding at a high stretch ratio) simultaneously with or after crosslinking, if necessary. Therefore, a method for producing a crosslinked molded article can be suitably adopted, in which a preformed article prepared by preforming the crosslinkable polymer composition of the present invention is crosslinked and then molded while applying a large strain (e.g., molding at a high stretch ratio). This production method can produce a crosslinked molded article that is excellent not only in resilience and compression set resistance but also in mechanical properties and dimensional stability. This production method is suitable for producing crosslinked molded articles such as fibers, films, and tubes. In this case, a known molding method (e.g., a stretching method) can be appropriately adopted depending on the desired shape of the crosslinked molded article, and the various crosslinking methods described above can be adopted as the crosslinking method.

[0149] [Applications] The crosslinked product obtained by crosslinking the crosslinkable polymer composition of the present invention has a good balance of high resilience and compression set resistance, and can therefore be suitably used in a variety of applications, such as clothing, daily necessities, medical devices, electronic devices, electrical appliances, packaging materials, transport equipment, building materials, and parts for these devices.

[0150] Furthermore, the crosslinked foam of the present invention has a well-balanced excellent resilience and compression set resistance, excellent homogeneity, and can have a low apparent density if necessary, and is therefore suitable for the various applications mentioned above, particularly for applications requiring excellent resilience, compression set resistance, and homogeneity, and also requiring light weight if necessary, such as various cushioning applications such as shoe midsoles, battery cushioning, and weather strips.

[0151] The present invention will be explained in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. Note that "parts" and "%" are by weight unless otherwise specified. The test methods used in these examples and comparative examples are as follows.

[0152] [Weight-average molecular weight and molecular weight distribution of hydrogenated block copolymer composition (whole)] A chart based on the polystyrene-equivalent molecular weight was obtained 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 Shodex (registered trademark) KF-404HQ columns manufactured by Showa Denko K.K. (column temperature: 40°C), and the detectors were a differential refractometer and an ultraviolet detector. The molecular weight was calibrated at 12 points using standard polystyrenes (5 to 3 million) manufactured by Polymer Laboratory.

[0153] [Weight Ratio of Each Block Copolymer] The weight ratio was determined from the area ratio of the peak corresponding to each block copolymer in the chart obtained by the above high performance liquid chromatography.

[0154] [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 (hydrogenated) block copolymer was reacted with ozone and reduced with lithium aluminum hydride to decompose the isoprene polymer block of the (hydrogenated) block copolymer. Specifically, the following procedure was performed. 300 mg of sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. The reaction vessel was placed in a cooling bath and cooled to -25°C. Ozone generated by an ozone generator was then introduced into the reaction vessel while oxygen was flowing into the reaction vessel at a flow rate of 170 ml / min. Thirty minutes after the start of the reaction, the completion of the reaction was confirmed by introducing the gas flowing out of the reaction vessel into an aqueous potassium iodide solution. Next, 50 ml of diethyl ether and 470 mg of lithium aluminum hydride were placed in a separate reaction vessel purged with nitrogen. While cooling the reaction vessel with ice water, the solution reacted with ozone was slowly added dropwise to the reaction vessel. The reaction vessel was then placed in a water bath, gradually heated, and refluxed at 40°C for 30 minutes. Dilute hydrochloric acid was then added dropwise to the reaction vessel in small amounts while stirring the solution, and the addition was continued until hydrogen generation was almost completely eliminated. After the reaction, the solid product formed in the solution was filtered, and the solid product was extracted with 100 ml of diethyl ether for 10 minutes. This extract and the filtrate were combined, 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-described method for measuring weight-average molecular weight, and the resulting value was taken as the weight-average molecular weight of the styrene polymer block.

[0155] [Weight-Average Molecular Weight of (Hydrogenated) Isoprene Polymer Block of Each Block Copolymer] The weight-average molecular weight of the corresponding styrene polymer block was subtracted from the weight-average molecular weight of each block copolymer determined as described above, and the weight-average molecular weight of the (hydrogenated) isoprene polymer block was determined based on the calculated value.

[0156] [Vinyl bond content of (hydrogenated) isoprene polymer block] Deuterated chloroform was used as the solvent. １It was determined based on H-NMR measurement.

[0157]

[0046] The styrene unit content of each block copolymer was determined based on the ratio of the detection intensities of the differential refractometer and the ultraviolet detector in the high performance liquid chromatography measurement. Copolymers having different styrene unit contents were prepared in advance, and a calibration curve was created using these copolymers.

[0158] [Styrene Unit Content of Hydrogenated Block Copolymer Composition (Total)] Deuterated chloroform was used as the solvent. １ It was determined based on H-NMR measurement.

[0159] [Olefin Hydrogenation Ratio (Mole %) of Hydrogenated Block Copolymer Composition (Total)] Deuterated chloroform was used as the solvent. １ The olefin amount was determined for each of the block copolymer composition before hydrogenation and the hydrogenated block copolymer composition after hydrogenation by H-NMR spectrum measurement, and the olefin hydrogenation rate (mol %) was calculated based on the difference between the olefin amounts before and after hydrogenation. １ In the H-NMR spectrum measurement, deuterated chloroform was used as the solvent, and a JMN-AL series AL400 (manufactured by JEOL) was used as the NMR measurement apparatus. In the present examples and comparative examples, both the block copolymer composition before hydrogenation and the hydrogenated block copolymer composition after hydrogenation contained only isoprene units as olefin-derived monomer units, and therefore the hydrogenation rate of isoprene was determined in the measurement, and this was taken as the olefin hydrogenation rate.

[0160] [Density of hydrogenated block copolymer composition] Volume 100 cm ３ Approximately 10 g of the hydrogenated block copolymer composition was filled into a measuring flask, and the mass of the filled hydrogenated block copolymer composition was accurately weighed. Next, the measuring flask filled with the hydrogenated block copolymer composition was accurately filled up to the marked line with isopropanol, taking care not to introduce air bubbles. The mass of the isopropanol added to the measuring flask was accurately weighed, and the density (g / cm) of the hydrogenated block copolymer composition was calculated based on the following formula (I): ３ The density (g / cm) of the hydrogenated block copolymer composition was calculated. ３) = [mass of hydrogenated block copolymer composition] ÷ (100 - [mass of isopropanol] ÷ [density of isopropanol at measurement temperature]) (I)

[0161] [Moldability of Crosslinkable Polymer Composition] In the examples and comparative examples, moldability was evaluated based on whether foam molding was possible. Good: Foam molding was possible. Poor: Foam molding was not possible.

[0162] [Apparent Density of Crosslinked Foam (Crosslinked Product)] The mass of the crosslinked foam (crosslinked product) was accurately weighed, and then the volume of the crosslinked foam (crosslinked product) was measured by the underwater displacement method. Based on these measurement results, the apparent density of the crosslinked foam (crosslinked product) was calculated.

[0163] [50% Compressive Stress] Using a universal testing machine (Instron Dual Column Tabletop Universal Testing System 5969, Load Cell Type, 50 kN), a sample of the crosslinked foam (crosslinked product) was compressed at a temperature of 23°C and a compression rate of 2.0 mm / min to obtain a compressive stress-strain curve. Based on the obtained compressive stress-strain curve, the 50% compressive stress of the crosslinked foam (crosslinked product) was determined.

[0164] [Compression Set] In accordance with JIS-K6262, the compression set of the crosslinked foam (crosslinked product) was measured under compression conditions of a compression ratio of 50%, a temperature of 50° C., and a compression time of 5 hours.

[0165] [Production Example 1] (1) Production of Block Copolymer Composition Before Hydrogenation 56.6 kg of cyclohexane, 397 mmol of dibutyl ether, and 1.18 kg of styrene were added to a pressure reactor. While stirring the entire contents at 50°C, 213 mmol of n-butyllithium (1.6 M solution) was added. After the addition was completed, the temperature was raised to 55°C and a polymerization reaction was carried out for 1 hour (first stage of polymerization). The polymerization conversion of styrene at this time was 100%.

[0166] Subsequently, 5.00 kg of isoprene was continuously added to the reactor over 1 hour while controlling the temperature to maintain a temperature of 50 to 60°C. After the addition of isoprene was completed, the polymerization reaction was continued for another 1 hour (second-stage polymerization). The polymerization conversion of isoprene at this time was 100%.

[0167] Next, 1.18 kg of styrene was continuously added over 1 hour while controlling the temperature to maintain it at 50 to 60°C. After the addition of styrene was completed, the polymerization reaction was continued for another 1 hour to obtain a solution containing a styrene-isoprene-styrene triblock copolymer having active terminals (third polymerization stage). The polymerization conversion of styrene at this time was 100%.

[0168] Next, 148 mmol of methanol was added as a polymerization terminator, and the mixture was mixed to deactivate some of the active ends of the styrene-isoprene-styrene triblock copolymer having active ends, thereby obtaining a solution containing a styrene-isoprene-styrene triblock copolymer that would become block copolymer B' for obtaining hydrogenated block copolymer B.

[0169] Thereafter, 2.65 kg of styrene was continuously added over 1 hour while continuing to control the temperature to maintain it at 50 to 60°C. After the addition of styrene was completed, the polymerization reaction was continued for another 1 hour to obtain a solution containing a styrene-isoprene-styrene triblock copolymer having active ends, which would become block copolymer A' for obtaining hydrogenated block copolymer A (fourth polymerization stage). The polymerization conversion of styrene at this time was 100%.

[0170] Finally, 278 mmol of methanol was added as a polymerization terminator and mixed to deactivate all of the active ends of the styrene-isoprene-styrene triblock copolymer, thereby completing the polymerization reaction. The amounts of each reagent used in the reaction are summarized in Table 1.

[0171] (2) Hydrogenation Reaction of Block Copolymer Composition Before Hydrogenation A solution containing the block copolymer composition before hydrogenation obtained above was subjected to a hydrogenation reaction to obtain a solution containing a hydrogenated block copolymer composition. The hydrogenation reaction was carried out by adding Ni(AcAc) ２The TIBAL catalyst was added in a proportion of 0.5% based on the block copolymer composition before hydrogenation, and the reaction was carried out under conditions of a hydrogen pressure of 3 MPa, a reaction temperature of 80°C, and a reaction time of 3 hours. A portion of the solution containing the hydrogenated block copolymer composition thus obtained was taken out and measured according to the method described above. The results are shown in Table 2.

[0172] (3) Recovery of Hydrogenated Block Copolymer Composition: 0.3 parts of 2,6-di-t-butyl-p-cresol as an antioxidant was added to 100 parts of the solution containing the hydrogenated block copolymer composition obtained as described above, and the mixture was mixed. The mixed solution was added dropwise in small amounts to warm water heated to 85 to 95°C to volatilize the solvent, resulting in a precipitate. The resulting precipitate was pulverized and dried with hot air at 85°C to recover a crumb-like hydrogenated block copolymer composition. The crumb-like hydrogenated block copolymer composition was fed into a single-screw extruder equipped with an underwater hot cut device at the tip of the extruder, and formed into cylindrical pellets with an average diameter of approximately 5 mm and an average length of approximately 5 mm. The pellets were placed in a hopper dryer heated to 60°C and dried for 10 hours while circulating dry air at 60°C to obtain a hydrogenated block copolymer composition. The density of the resulting hydrogenated block copolymer composition was then measured according to the method described above. The results are shown in Table 2.

[0173] [Preparation Examples 2 to 4] Hydrogenated block copolymer compositions were obtained and measurements were carried out in the same manner as in Preparation Example 1, except that the amounts of each reagent used in the reaction were changed to those shown in Table 1. The results are shown in Table 2.

[0174] In Production Examples 3 and 4, after the third polymerization stage, methanol was added as a polymerization terminator in the amount shown in Table 1 and mixed to deactivate all of the active ends of the styrene-isoprene-styrene triblock copolymer having active ends, thereby completing the polymerization reaction and obtaining a solution containing the block copolymer composition before hydrogenation. A hydrogenated block copolymer composition was then obtained in the same manner as in Production Example 1, except that the obtained solution containing the block copolymer composition before hydrogenation was used.

[0175]

[0176]

[0177] Examples 1 to 4, Comparative Examples 1 to 4 Using a roll mixer, the ingredients shown in Table 3 were kneaded at a kneading temperature of 120°C to obtain a crosslinkable polymer composition. The obtained crosslinkable polymer composition was placed in a mold, and using a compression molding machine, the crosslinkable polymer composition in the mold was compressed at a temperature of 160°C and a pressure of 15 MPa for 10 minutes, and then the mold was opened to crosslink and foam the crosslinkable polymer composition, thereby producing a crosslinked foam (crosslinked product). The moldability of the crosslinkable polymer composition was then evaluated according to the above method. The results are shown in Table 3.

[0178] In Comparative Example 1, when the mold was opened, the foaming gas leaked out of the crosslinkable polymer composition, and the crosslinkable polymer composition could not be foamed.

[0179] The crosslinked foam (crosslinked product) thus produced was allowed to stand at room temperature for 24 hours, and then a sample measuring 3 cm long x 3 cm wide x 1 cm thick was cut out. The resulting sample was used to measure the apparent density, 50% compression stress, and compression set of the crosslinked foam (crosslinked product). The results are shown in Table 3. In Comparative Example 1, no foam was obtained, so the apparent density of the residue remaining in the mold was measured.

[0180] The components shown in Table 3 are as follows: EVA: crosslinked ethylene-vinyl acetate copolymer (vinyl acetate unit content: 15%), density: 0.936 g / cm ３ , manufactured by Tosoh Corporation, trade name "Ultrathene 630" LDPE: low-density polyethylene, density 0.920 g / cm ３ , manufactured by Japan Polypropylene Corporation, trade name "Novatec YF30" ADCA: Azodicarbonamide, chemical foaming agent, manufactured by Eiwa Kasei Co., Ltd., trade name "ADCA AY-7" Foaming assistant: Foaming assistant mainly composed of urea, manufactured by Eiwa Kasei Co., Ltd., trade name "Celpaste K5" Dicumyl peroxide: Crosslinking agent, manufactured by NOF Corporation, trade name "Perkmyl D"

[0181]

[0182] As shown in Table 3, a crosslinkable polymer composition containing a hydrogenated block copolymer A represented by general formula (A) and a hydrogenated block copolymer B represented by general formula (B) in a specific weight ratio (A / B) and having an olefin hydrogenation rate of 10 to 100%, and a polyolefin thermoplastic resin C in a specific ratio (C / (A+B)), and further containing a crosslinking agent, resulted in the production of a crosslinked foam (crosslinked product) that had excellent moldability and a well-balanced combination of high resilience and compression set resistance (Examples 1 to 4).

[0183] On the other hand, when the polyolefin thermoplastic resin C was not contained, a crosslinked foam (crosslinked product) was not obtained, resulting in poor moldability (Comparative Example 1). Furthermore, when the content of the hydrogenated block copolymer composition was too low, the resulting crosslinked foam (crosslinked product) had poor compression set resistance (Comparative Example 2). Furthermore, when the hydrogenated block copolymer A represented by general formula (A) was not contained, the resulting crosslinked foam (crosslinked product) did not have both high resilience and compression set resistance (Comparative Examples 3 and 4).

Claims

1. A hydrogenated block copolymer composition having hydrogenated block copolymer A represented by the following general formula (A) and hydrogenated block copolymer B represented by the following general formula (B), Polyolefin-based thermoplastic resin C, It contains a crosslinking agent, The hydrogenation rate of the olefin in the polymer component constituting the hydrogenated block copolymer composition is 10 to 100%. In the hydrogenated block copolymer composition, the weight ratio (A / B) of hydrogenated block copolymer A to hydrogenated block copolymer B is 10 / 90 to 80 / 20. A crosslinkable polymer composition in which the ratio of the content of the polyolefin-based thermoplastic resin C to the total content of the hydrogenated block copolymer A and the hydrogenated block copolymer B (C / (A+B)) is 5 / 95 to 80 / 20 by weight. Ar1 ａ -HD ａ -Ar2 ａ (A) Ar1 ｂ -HD ｂ -Ar2 ｂ (B) (In the above general formula (A) and general formula (B), Ar1 ａ , Ar2 ａ , Ar1 ｂ , and Ar2 ｂ are aromatic vinyl polymer blocks, HD ａ and HD ｂ are hydrogenated polymer blocks of conjugated diene polymers, and the ratio of the weight average molecular weight (Mw(Ar1 ａ )) of Ar1 ａ to the weight average molecular weight (Mw(Ar2 ａ )) of Ar2 ａ (Mw(Ar2 ａ ) / Mw(Ar1 ａ )) is 3.0 to 20, and the ratio of the weight average molecular weight (Mw(Ar2 ｂ )) of Ar2 ｂ to the weight average molecular weight (Mw(Ar1 ｂ )) of Ar1 ｂ (Mw(Ar2 ｂ ) / Mw(Ar1 ｂ )) is 0.95 to 1.05.)

2. The crosslinkable polymer composition according to claim 1, wherein aromatic vinyl monomer units account for 20 to 70% by weight of the total repeating units of the polymer component of the hydrogenated block copolymer composition.

3. In the above general formulas (A) and (B) of the hydrogenated block copolymer composition, HD ａ and HD ｂ The crosslinkable polymer composition according to claim 1 or 2, wherein the vinyl bond content is 1 to 80 mol%.

4. In the above general formulas (A) and (B) of the hydrogenated block copolymer composition, Ar1 ａ Ar1 ｂ , and Ar2 ｂ The weight-average molecular weights of each are in the range of 2,000 to 40,000, and HD ａ and HD ｂ The crosslinkable polymer composition according to claim 1 or 2, wherein the weight-average molecular weight of each is in the range of 10,000 to 300,000.

5. The crosslinkable polymer composition according to claim 1 or 2, wherein the weight-average molecular weight of all polymer components constituting the hydrogenated block copolymer composition is 30,000 to 400,000.

6. The crosslinkable polymer composition according to claim 1 or 2, wherein the polyolefin-based thermoplastic resin C is an ethylene-based resin.

7. The crosslinkable polymer composition according to claim 1 or 2, wherein the ratio of the content of the polyolefin-based thermoplastic resin C to the total content of the hydrogenated block copolymer A and the hydrogenated block copolymer B (C / (A+B)) is 15 / 85 to 50 / 50 by weight.

8. The crosslinking polymer composition according to claim 1 or 2, further containing a foaming agent.

9. The crosslinkable polymer composition according to claim 8, wherein the foaming agent is a chemical foaming agent.

10. A crosslinked product obtained by crosslinking the crosslinkable polymer composition according to claim 1 or 2.

11. A crosslinked foam obtained by crosslinking and foaming the crosslinkable polymer composition according to claim 1 or 2.

12. The crosslinked foam according to claim 11, which is the midsole of a shoe.

13. The cross-linked foam according to claim 11, which is a cushioning material for batteries.

14. The crosslinked foam according to claim 11, which is a weatherstrip.

15. Apparent density is 0.06–0.60 g / cm³ ３ The crosslinked foam according to claim 11.