Foam body and buffer material

Abstract

Provided is a foam body obtained by foaming a hydrogenated block copolymer composition containing a hydrogenated block copolymer A represented by a specific general formula (A) and a hydrogenated block copolymer B represented by a specific general formula (B). The weight ratio (A / B) of the hydrogenated block copolymer A to the hydrogenated block copolymer B is 10 / 90 to 80 / 20. In polymer components forming the hydrogenated block copolymer composition, the rate of hydrogenation of olefins is 10-100%.

Description

Foam and Cushioning

[0001] The present invention relates to a foam, and more particularly to a foam having a low initial modulus and excellent cushioning properties.

[0002] Foams made from various polymers are used in cushioning applications, which require excellent shock-absorbing properties. On the other hand, for applications such as shoe sole components and battery cushioning, a low initial modulus of elasticity is also required, since a lower resilience in the initial microdeformation region is preferable.

[0003] For example, Patent Document 1 describes a hydrogenated block copolymer having a polymer block (A) containing more than 70 mol % of structural units derived from an aromatic vinyl compound and a polymer block (B) containing 30 mol % or more of structural units derived from a conjugated diene compound, and further satisfying the following conditions: Condition (1): The content of polymer block (A) in the hydrogenated block copolymer is 1 to 30 mass %. Condition (2): The conjugated diene compound contains isoprene. Condition (3): In the structural units derived from the conjugated diene compound, the total content of 1,2-bond units and 3,4-bond units is 60 mol % or more. Condition (4): The hydrogenation rate of polymer block (B) is 60 mol % or more. Condition (5): In accordance with JIS K7244-10 (2005), a temperature range exists in which tan δ is 1.0 or greater, as measured under the conditions of a strain of 0.1%, a frequency of 1 Hz, a measurement temperature of −70 to 100° C., and a heating rate of 3° C. / min, and the maximum width of the temperature range is 16° C. or greater.

[0004] Patent Document 1 also describes a shoe sole material containing a resin composition of the hydrogenated product of the block copolymer. However, a foam obtained using the resin composition of the hydrogenated product of the block copolymer could not achieve both a low initial modulus of elasticity and excellent cushioning properties.

[0005] International Publication No. 2019 / 103047

[0006] An object of the present invention is to provide a foam having a low initial modulus of elasticity and excellent cushioning properties.

[0007] The present inventors have conducted studies to achieve the above-mentioned object and have found that a foam obtained by foaming a hydrogenated block copolymer composition containing a hydrogenated block copolymer A represented by a specific general formula (A) and a hydrogenated block copolymer B represented by a specific general formula (B), wherein the weight ratio of hydrogenated block copolymer A to hydrogenated block copolymer B is within a specific range and the hydrogenation rate of olefin in the polymer components constituting the hydrogenated block copolymer composition is within a specific range, can achieve both a low initial modulus of elasticity and excellent cushioning properties, thereby completing the present invention.

[0008] That is, according to the present invention, there is provided a foam obtained by foaming 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), wherein the weight ratio (A / B) of the hydrogenated block copolymer A to the hydrogenated block copolymer B is 10 / 90 to 80 / 20, and the hydrogenation rate of olefin in the polymer components constituting the hydrogenated block copolymer composition is 10 to 100%. 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 2.6 to 66, 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.

[0009] In the foam of the present invention, it is preferable that the proportion of aromatic vinyl monomer units in all repeating units of the polymer components constituting the hydrogenated block copolymer composition is 10 to 75% by weight. ａ and HD ｂ In the foam of the present invention, it is preferable that the vinyl bond content of each of Ar1 in the general formula (A) and the general formula (B) is 1 to 80 mol %. ａ , Ar1 ｂ , and Ar2 ｂ The weight average molecular weight of each of the above ranges from 2,000 to 40,000, and HD ａ and HD ｂ and the weight average molecular weights of the respective hydrogenated block copolymers A and B are preferably in the range of 10,000 to 300,000. In the foam of the present invention, the weight proportion of the total of the hydrogenated block copolymer A and the hydrogenated block copolymer B in the polymer components constituting the hydrogenated block copolymer composition is preferably 30 to 100 wt %. In the foam of the present invention, the weight average molecular weight of all the polymer components constituting the hydrogenated block copolymer composition is preferably 30,000 to 400,000. The foam of the present invention has an apparent density of 0.1 to 0.7 g / cm ３ It is preferable that:

[0010] The present invention also provides a cushioning material containing the foam.

[0011] According to the present invention, a foam having a low initial modulus of elasticity and excellent cushioning properties can be provided.

[0012] <Foam> The foam of the present invention is obtained by foaming a hydrogenated block copolymer composition containing a hydrogenated block copolymer A represented by general formula (A) described below and a hydrogenated block copolymer B represented by general formula (B) described below.

[0013] (Hydrogenated Block Copolymer Composition) The hydrogenated block copolymer composition used in the present invention contains 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 -HD ａ -Ar2 ａ (A) Ar1 ｂ -HD ｂ -Ar2 ｂ (B)

[0014] In the above general formula (A), Ar1 ａ , Ar2 ａ is an aromatic vinyl polymer block, 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 2.6 to 66. ａ is a hydrogenated polymer block of a conjugated diene polymer.

[0015] In addition, in the above general formula (B), Ar1 ｂ , Ar2 ｂ is an aromatic vinyl polymer block, 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. ｂ is a hydrogenated polymer block of a conjugated diene polymer.

[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 ｂmay 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. ｂ may 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 ａWeight 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 2.6 to 66, and therefore, the aromatic vinyl polymer block Ar1 has 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 2.6 to 66. ａ ) / Mw(Ar1 ａ If Mw(Ar2) is too small or too large, it becomes difficult to achieve both a low initial modulus of elasticity and excellent shock-absorbing properties of the foam. ａ ) / Mw(Ar1 ａ ) is preferably in the range of 3 to 60, more preferably in the range of 3.5 to 50, even more preferably in the range of 4 to 40, and particularly preferably in the range of 4.5 to 35. ａ ) / Mw(Ar1 ａ By setting the initial modulus of elasticity (Mw) and the number average molecular weight (Mn) of the polymer or polymer block in the present invention within the above range, it is possible to achieve both a low initial modulus of elasticity and excellent shock absorption properties at a higher level. In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) of the polymer or polymer block are determined as polystyrene-equivalent values ​​measured by high performance liquid chromatography.

[0026] In addition, the 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)) is preferably 2,000 to 40,000, more preferably 2,500 to 30,000, and even more preferably 3,000 to 10,000.

[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 8,000 to 120,000, even more preferably 10,000 to 100,000, and still more preferably 10,000 to 80,000.

[0028] 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.

[0029] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer A ａ The vinyl bond content (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) of the hydrogenated polymer block HD is preferably 1 to 80 mol %, more preferably 2 to 75 mol %, and even more preferably 3 to 70 mol %. By setting the vinyl bond content within the above range, it is possible to achieve both a low initial modulus of elasticity and excellent cushioning properties of the foam at a higher level. Furthermore, from the viewpoint of achieving an even lower initial modulus of elasticity, it is preferable to use a hydrogenated polymer block HD. ａ The vinyl bond content of the hydrogenated polymer block of the conjugated diene polymer may be 4 to 30 mol %, 5 to 20 mol %, or 5 to 15 mol %. １ It can be determined by H-NMR.

[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 43 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 detection intensity ratio between a differential refractometer and an ultraviolet detector in high performance liquid chromatography measurement.

[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. The weight average molecular weight (Mw(Ar1)) of each polymer block constituting the hydrogenated block copolymer A is ａ ), Mw(Ar2 ａ ), Mw(HD ａ )) and the weight-average molecular weight of the hydrogenated block copolymer A as a whole within the above-mentioned preferred ranges, the foam can achieve both a low initial modulus of elasticity and excellent cushioning properties at an even higher level.

[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 ｂ The 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 30,000, and even more preferably 3,000 to 10,000. 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 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.

[0036] The hydrogenated polymer block HD of the conjugated diene polymer constituting the hydrogenated block copolymer B ｂThe vinyl bond content (the proportion of 1,2-vinyl bonds and 3,4-vinyl bonds in all conjugated diene monomer units) of the hydrogenated polymer block HD is preferably 1 to 80 mol %, more preferably 2 to 75 mol %, and even more preferably 3 to 70 mol %. By setting the vinyl bond content within the above range, it is possible to achieve both a low initial modulus of elasticity and excellent cushioning properties of the foam at a higher level. Furthermore, from the viewpoint of achieving an even lower initial modulus of elasticity, it is preferable to use a hydrogenated polymer block HD. ｂ The vinyl bond content of the hydrogenated polymer block of the conjugated diene polymer may be 4 to 30 mol %, 5 to 20 mol %, or 5 to 15 mol %. 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.

[0037] 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 ｂThat is, as shown in the above formula, the hydrogenated polymer block HD of the conjugated diene polymer ｂ is 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.

[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 5 to 40% by weight, more preferably 10 to 38% by weight, and even more preferably 15 to 35% by weight. By setting the content of aromatic vinyl monomer units within the above range, it is possible to achieve a high level of both a low initial modulus of elasticity and excellent cushioning properties of the foam. 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. The weight average molecular weight (Mw(Ar1)) of each polymer block constituting the hydrogenated block copolymer B is ｂ ), Mw(Ar2 ｂ ), Mw(HD ｂ ) and the weight average molecular weight of the hydrogenated block copolymer B as a whole within the above-mentioned preferred range, the foam can achieve both a low initial modulus of elasticity and excellent cushioning properties at a higher level.

[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 a low initial modulus of elasticity and excellent cushioning properties. The weight ratio (A / B) is preferably 12 / 88 to 60 / 40, more preferably 15 / 85 to 50 / 50. By setting the weight ratio of hydrogenated block copolymer A to hydrogenated block copolymer B within the above range, the foam can achieve both a low initial modulus of elasticity and excellent cushioning properties at a higher level. 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 may contain a polymer component other than the hydrogenated block copolymer A and the hydrogenated block copolymer B.

[0043] The weight proportion of the total of hydrogenated block copolymer A and hydrogenated block copolymer B in the polymer components constituting the hydrogenated block copolymer composition is not particularly limited, but is preferably 30 to 100% by weight, more preferably 50 to 100% by weight, even more preferably 70 to 100% by weight, even more preferably 90 to 100% by weight, particularly preferably 95 to 100% by weight, and most preferably substantially 100% by weight (i.e., containing no polymer components other than hydrogenated block copolymer A and hydrogenated block copolymer B).

[0044] Foams containing only elastomers as the polymer component tend to be prone to excessive deformation and therefore have poor cushioning properties, whereas the use of both elastomers and non-elastomeric polymers tends to prevent excessive deformation of the foam but also increases the initial modulus of elasticity.

[0045] In contrast, the foam of the present invention can achieve both a low initial modulus of elasticity and excellent shock-absorbing properties, particularly when the weight ratio of the total of hydrogenated block copolymer A and hydrogenated block copolymer B is relatively high as described above.

[0046] Examples of polymer components other than hydrogenated block copolymer A and hydrogenated block copolymer B include aromatic vinyl-conjugated diene-aromatic vinyl block copolymers other than hydrogenated block copolymer A and 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 polyolefins, polyvinyl chloride, acrylonitrile-styrene copolymers, acrylonitrile-butadiene-styrene copolymers, and polyphenylene ether; and the like.

[0047] The hydrogenated block copolymer composition used in the present invention has an olefin hydrogenation rate in the range of 10 to 100% in the polymer components constituting the hydrogenated block copolymer composition. Here, the hydrogenation rate of olefin refers to the hydrogenation rate of olefin in all polymer components constituting the hydrogenated block copolymer composition, and specifically refers to the proportion (mol %) of hydrogenated non-aromatic carbon-carbon double bonds in all polymer components before hydrogenation.

[0048] The hydrogenation rate of the olefin in the polymer components constituting the hydrogenated block copolymer composition used in the present invention is in the range of 10 to 100%. If the hydrogenation rate of the olefin is too low, the composition will be excessively prone to deformation and will have poor cushioning properties. The hydrogenation rate of the olefin is preferably 20 to 100%, more preferably 30 to 100%, even more preferably 50 to 100%, particularly preferably 70 to 100%, and most preferably 90 to 100%. By setting the hydrogenation rate of the olefin within the above range, it is possible to achieve both a low initial modulus of elasticity and excellent cushioning properties of the foam at a higher level. The hydrogenation rate of the olefin can be adjusted by using deuterated chloroform as a solvent. １ It can be determined by H-NMR spectrum measurement.

[0049] The hydrogenated block copolymer composition used in the present invention may have an olefin hydrogenation rate within the above range, but the iodine value of the polymer components constituting the hydrogenated block copolymer composition is preferably 0 to 300 g / L. ２ / 100g, and preferably 0 to 150g ２ / 100g, more preferably 0 to 125g / 100g. ２ It is more preferable that the range is 0 to 100 g / 100 g. ２ It is particularly preferable that the range is 0 to 75 g / 100 g. ２ It is particularly preferable that the range is 0 to 30 g / 100 g. ２ / 100g is most preferable. By setting the iodine value within the above range, it is possible to achieve a high level of both a low initial modulus of elasticity and excellent cushioning properties of the foam. The iodine value can be determined in accordance with JIS K0070.

[0050] The proportion of aromatic vinyl monomer units in all repeating units of the polymer components constituting the hydrogenated block copolymer composition used in the present invention (hereinafter sometimes referred to as the "total aromatic vinyl monomer unit content") is preferably 10 to 75 wt%, more preferably 15 to 70 wt%, and even more preferably 20 to 65 wt%. By setting the total aromatic vinyl monomer unit content within the above range, it is possible to achieve a foam that has both a low initial modulus of elasticity and excellent cushioning properties at a higher level. Furthermore, from the viewpoint of achieving an even lower initial modulus of elasticity, the total aromatic vinyl monomer unit content may be 22 to 50 wt%, 24 to 45 wt%, or 26 to 40 wt%. The total aromatic vinyl monomer unit content can be easily adjusted by 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 and adjusting the blending amounts of these components. The total aromatic vinyl monomer unit content can be easily adjusted by 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 and adjusting the blending amounts of these components. １ It can be determined by H-NMR measurement.

[0051] 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.

[0052] 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.

[0053] 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 1.01 to 10, more preferably 1.02 to 5, and even more preferably 1.03 to 3.

[0054] The hydrogenated block copolymer composition used in the present invention may further contain, as necessary, various compounding agents such as antioxidants, foaming agents, foaming aids, processing aids, fillers, pigments, antistatic agents, flame retardants, water repellents, waterproofing agents, electrical conductivity imparting agents, thermal conductivity imparting agents, electromagnetic wave shielding agents, fluorescent agents, antibacterial agents, light stabilizers, ultraviolet absorbers, dyes, lubricants, etc. The content of these compounding agents in the hydrogenated block copolymer composition is not particularly limited, but may be, for example, 0 to 50% by mass, or 5 to 30% by mass.

[0055] Examples of antioxidants 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. One type of antioxidant may be used alone, or two or more types may be used in combination. The content of the antioxidant in the hydrogenated block copolymer composition is not particularly limited, but is preferably 10 parts by weight or less, and more preferably 0.5 to 5 parts by weight, per 100 parts by weight of the hydrogenated block copolymer composition.

[0056] (Foam) The foam of the present invention is produced by foaming the hydrogenated block copolymer composition described above. The foam of the present invention has a low initial modulus of elasticity and excellent cushioning properties because it is produced by foaming the hydrogenated block copolymer composition containing hydrogenated block copolymer A and hydrogenated block copolymer B in specific weight ratios and having an olefin hydrogenation rate within a specific range.

[0057] The apparent density (specific gravity) of the foam of the present invention is not particularly limited, but is preferably 0.1 to 0.7 g / cm ３ is preferably 0.1 to 0.6 g / cm ３ More preferably, it is 0.1 to 0.5 g / cm ３ is preferably 0.1 to 0.4 g / cm ３ By setting the apparent density (specific gravity) within the above range, it is possible to achieve a foam having a low initial modulus of elasticity and excellent cushioning properties at a higher level, while also achieving excellent strength.

[0058] The foam of the present invention is not particularly limited as long as it has closed pores or continuous pores, but it is preferable that it has closed pores, and it is more preferable that it has fine closed pores (for example, bubbles on the order of microns) dispersed throughout the foam.

[0059] The porosity of the foam of the present invention is not particularly limited, but is preferably 90 to 40% by volume, and more preferably 80 to 50% by volume. By setting the porosity within the above range, the foam can achieve both a low initial modulus of elasticity and excellent cushioning properties at a higher level, while also achieving excellent strength.

[0060] The shape of the foam of the present invention is not particularly limited, and may be various shapes depending on the application.

[0061] <Method for Producing Foam> The foam of the present invention can be produced by producing the hydrogenated block copolymer composition used in the present invention and then foaming the hydrogenated block copolymer composition.

[0062] (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, but 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.

[0063] 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.

[0064] <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.

[0065] 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.

[0066] 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.

[0067] 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.

[0068] 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.

[0069] 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.

[0070] 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.

[0071] 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.

[0072] 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, dibutyl ether, 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.

[0073] 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.

[0074] 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.

[0075] 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.

[0076] <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.

[0077] 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.

[0078] 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).

[0079] <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.

[0080] 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.

[0081] 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).

[0082] <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'.

[0083] The block copolymer B′ obtained in the step (4) is the block copolymer before hydrogenation for obtaining the hydrogenated block copolymer B.

[0084] 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.

[0085] 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.

[0086] 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.

[0087] <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'.

[0088] 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.

[0089] 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)).

[0090] <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.

[0091] 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.

[0092] 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.

[0093] 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.

[0094] 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.

[0095] <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).

[0096] 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.

[0097] 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.

[0098] 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.

[0099] 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.

[0100] 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.

[0101] <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.

[0102] <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'.

[0103] The block copolymer B′ obtained in the step (3a) is the block copolymer before hydrogenation for obtaining the hydrogenated block copolymer B.

[0104] 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.

[0105] 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.

[0106] 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.

[0107] <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'.

[0108] 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.

[0109] 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 set 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)).

[0110] <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.

[0111] The hydrogenated block copolymer composition produced as described above may be blended with optional additives, such as antioxidants, at any time. The blending method for the additives is not particularly limited, and examples include a method of heating and melt-mixing the components using a kneading device such as a Banbury mixer, kneader, Labo Plastomill, single-screw extruder, or twin-screw extruder, or a method of preparing a solvent in which the components are dissolved and then removing the solvent by heating or the like. Alternatively, the hydrogenated block copolymer composition may be obtained by preparing a solution containing block copolymer B' before hydrogenation to obtain hydrogenated block copolymer B and block copolymer A' before hydrogenation to obtain hydrogenated block copolymer A, blending the additives therein, and then subjecting the solution to a hydrogenation step. Alternatively, a solution containing hydrogenated block copolymer B and hydrogenated block copolymer A may be prepared, and blending the additives therein.

[0112] (Method for Foaming Hydrogenated Block Copolymer Composition) The foam of the present invention can be produced by foaming the hydrogenated block copolymer composition produced above.

[0113] The foam of the present invention can be preferably produced by a method in which a hydrogenated block copolymer composition and a physical blowing agent are mixed, and then the physical blowing agent dissolved or dispersed in the hydrogenated block copolymer composition is converted into a gas phase.

[0114] 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.

[0115] The foam of the present invention can be produced, for example, using an injection molding machine. Specifically, the thermoplastic components of the hydrogenated block copolymer composition are plasticized in a cylinder while a physical blowing agent is injected into the cylinder to dissolve or disperse the physical blowing agent in the plasticized components of the hydrogenated block copolymer composition. The resulting mixture is then injected into a mold, and the physical blowing agent in the mixture is converted into a gas phase after or simultaneously with injection, thereby producing a foam. In particular, from the viewpoint of being able to produce a foam in which micron-order bubbles are uniformly dispersed, it is preferable to use an injection molding machine and a supercritical fluid as the physical blowing agent.

[0116] 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.

[0117] The injection molding conditions are not particularly limited as long as they allow injection molding of the hydrogenated block copolymer composition in a state in which the physical blowing agent is dissolved or dispersed in the plasticized component.

[0118] In the above manufacturing method, various other melt molding machines can be used instead of the injection molding machine.

[0119] Alternatively, the foam of the present invention may be produced by mixing the hydrogenated block copolymer composition with a chemical blowing agent, and then foaming the chemical blowing agent dispersed in the hydrogenated block copolymer composition. The chemical blowing agent is a blowing agent that generates gas by chemical reaction or thermal decomposition. Examples of chemical blowing agents include inorganic chemical blowing agents such as sodium bicarbonate and ammonium carbonate, and organic chemical blowing agents such as azodicarbonamide.

[0120] The foam of the present invention has a low initial modulus of elasticity and excellent shock-absorbing properties, and therefore can be suitably used as a shock-absorbing material. In particular, according to the present invention, a low initial modulus of elasticity can be achieved, and at the same time, a compressive stress σ at a strain of 0.4 can be achieved. ０．４ can be preferably set to 0.2 to 0.8 MPa, more preferably 0.3 to 0.7 MPa, and the strain ε at a compressive stress of 1 MPa １ＭＰａ The initial elastic modulus is low, and the compressive stress σ at a strain of 0.4 is preferably 0.45 to 0.85, and more preferably 0.55 to 0.75. ０．４ and strain ε at compressive stress of 1 MPa １ＭＰａ When the molecular weight is within the above range, the material can be suitably used as a shoe sole member or a cushioning material for batteries, and can be particularly suitably used as a shoe sole member.

[0121] For example, when the foam of the present invention is used as a shoe sole component, a soft and comfortable feeling is achieved when putting one's foot into the shoe, and excessive deformation or excessive rebound does not occur when a relatively large load is applied to the shoe sole due to walking, exercise, etc.

[0122] Furthermore, when the foam of the present invention is used as a cushioning material for batteries, even if a relatively small deformation such as expansion of the battery occurs, excessive rebound does not occur, thereby suppressing deterioration over time of the battery container, etc., and providing an appropriate cushioning effect when a relatively large load is applied.

[0123] The foam of the present invention can be used in a variety of applications, including but not limited to the above. For example, it can be suitably used in sporting goods applications such as inflatable balls, sports gloves (e.g., football gloves or boxing gloves), golf ball components, rackets, and protective elements (jackets, helmet inner elements, shells, etc.). It can also be suitably used in various applications in various machinery and equipment parts such as audio equipment and office automation equipment; various parts for home appliances; various building materials for apartment buildings and the like; the transportation industry, such as rail soles for railways and automobile parts; the electrical and electronics industry; and the manufacturing industry.

[0124] 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.

[0125] [Weight-average molecular weight, molecular weight distribution] A chart based on 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.

[0126] [Weight Ratio of Each Block Copolymer in the (Hydrogenated) Block Copolymer Composition] This 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.

[0127] [Weight-Average Molecular Weight of Styrene Polymer Block of (Hydrogenated) 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.

[0128] [Weight-Average Molecular Weight of (Hydrogenated) Isoprene Polymer Block of (Hydrogenated) Block Copolymer] The weight-average molecular weight of the corresponding styrene polymer block was subtracted from the weight-average molecular weight of the (hydrogenated) block copolymer obtained as described above, and the weight-average molecular weight of the (hydrogenated) isoprene polymer block was determined based on the calculated value.

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[0130] [Content of styrene units in the entire (hydrogenated) block copolymer composition] Deuterated chloroform was used as the solvent. １ It was determined based on H-NMR measurement.

[0131] [Vinyl bond content of (hydrogenated) isoprene polymer block] Deuterated chloroform was used as the solvent. １ It was determined based on H-NMR measurement.

[0132] [Olefin Hydrogenation Ratio (Mole %) of (Hydrogenated) Block Copolymer Composition] 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.

[0133] [Iodine Value of (Hydrogenated) Block Copolymer Composition] The iodine value was measured in accordance with JIS K0070.

[0134] [Viscosity Retention Rate] A thermal degradation test (170°C x 1 hour; in the presence of air) was conducted on the hydrogenated block copolymer composition, and the melt viscosity was measured before and after the thermal degradation test. The viscosity retention rate was calculated using the following formula. A higher viscosity retention rate indicates that the hydrogenated block copolymer composition has better thermal stability, and that thermal degradation during foam molding of the hydrogenated block copolymer composition is suppressed, making it possible to obtain foams with stable quality. Viscosity Retention Rate (%) = (Melt Viscosity After Thermal Degradation Test / Melt Viscosity Before Thermal Degradation Test) x 100. The melt viscosity was measured using a flow tester CFT-500C (manufactured by Shimadzu Corporation) at a temperature of 180°C and a load of 100 kgf / cm. ２ The measurement was carried out under the condition of a die shape of 1 mmφ×10 mm.

[0135] [Specific Gravity and Porosity of Foam] The specific gravity (apparent density) of the foam was measured according to JIS K 7311:1995 (underwater displacement method). The specific gravity (true density) of the hydrogenated block copolymer composition was measured in the same manner, and the porosity of the foam was calculated from the specific gravity (apparent density) of the foam and the specific gravity (true density) of the hydrogenated block copolymer composition.

[0136] [Initial elastic modulus E ０ , compressive stress σ at strain 0.4 ０．４ and strain ε at compressive stress of 1 MPa １ＭＰａ The foam was cut into a cylindrical shape with a diameter of 29 mm and a height of 12 mm, and the sample piece was compressed at 23°C at a strain rate of 0.1 mm / sec using an autograph precision universal testing machine (manufactured by Shimadzu Corporation, product name "AG-50kNIS MS type") to obtain a compressive stress-strain curve. The initial modulus of elasticity E ０ From the obtained compressive stress-strain curve, the compressive stress σ at a strain of 0.4 was calculated. ０．４ and strain ε at compressive stress of 1 MPa １ＭＰａ asked for.

[0137] Example 1 (1) Production of a Block Copolymer Composition Before Hydrogenation 56.6 kg of cyclohexane, 505 mmol of dibutyl ether, and 1.22 kg of styrene were added to a pressure reactor. While stirring the entire contents at 40°C, 270.6 mmol of n-butyllithium (1.6 M solution) was added. After the addition was completed, the temperature was raised to 50°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% by weight.

[0138] Subsequently, 6.49 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%.

[0139] Next, 1.22 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%.

[0140] Next, 195 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.

[0141] Thereafter, 1.06 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%.

[0142] Finally, 345 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.

[0143] (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) ２ The -TIBAL catalyst was added in a proportion of 0.5% by weight 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.

[0144] A portion of the solution containing the hydrogenated block copolymer composition thus obtained was removed, and the weight average molecular weight of each block copolymer contained in the composition, the weight ratio of each block copolymer in the composition, the weight average molecular weight of the styrene polymer block of each block copolymer, the weight average molecular weight of the isoprene polymer block of each block copolymer, the styrene unit content of each block copolymer, the styrene unit content of the block copolymer composition (as a whole), the vinyl bond content of the isoprene polymer block of each block copolymer, and the olefin hydrogenation rate were determined. These values ​​are summarized in Table 2.

[0145] (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 mixed, and the mixed solution was added dropwise in small amounts to warm water heated to 85 to 95°C to volatilize the solvent and obtain a precipitate. The obtained precipitate was pulverized and dried with hot air at 85°C to recover a crumb-like hydrogenated block copolymer composition.

[0146] The resulting crumb-like hydrogenated block copolymer composition was then 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 pellet-like hydrogenated block copolymer composition was then placed in a hopper dryer heated to 60°C and dried for 10 hours while circulating dry air at 60°C. The iodine value of the resulting hydrogenated block copolymer composition was measured. The results are shown in Table 2.

[0147] (4) Production of Foam The resulting hydrogenated block copolymer composition was foam-molded to produce a foam measuring 170 mm x 170 mm x 13 mm using the following molding machine: An Arburg Allrounder 520A 150T injection molding machine equipped with a Trexel Series II system capable of injecting a physical blowing agent using Mucell (registered trademark) technology and a mold-opening system (core-back method). The operating parameters were as follows: - Sheath temperature (°C): 230°C - Mold geometry (mm): 170 x 170 x 4 - Injection speed: 150 mm / s - Maintenance time before mold opening: 6-10 seconds - Maintenance pressure: 300 MPa - Cooling time (s): 70 seconds - Mold temperature: 40°C - Mold opening length: adjusted so as to obtain a foam with a thickness of 13 mm (variable up to a maximum of 30 mm) - Mold opening speed: 0.28 mm / s A blowing agent was introduced at a rate of 1.5% by weight relative to the weight of the hydrogenated block copolymer composition. As the blowing agent, nitrogen (N ２ ) was used.

[0148] [Example 2] A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1, and the reaction time in the hydrogenation reaction was changed from 3 hours to 0.5 hours. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2.

[0149] [Example 3] A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1, and the reaction time in the hydrogenation reaction was changed from 3 hours to 0.2 hours. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2.

[0150] [Example 4] A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2.

[0151] Example 5 (1) Production of Block Copolymer Composition Before Hydrogenation 56.6 kg of cyclohexane, 769 mmol of dibutyl ether, and 1.29 kg of styrene were added to a pressure reactor. While stirring the entire contents at 40°C, 412.4 mmol of n-butyllithium (1.6 M solution) was added. After the addition was completed, the temperature was raised to 50°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% by weight.

[0152] Subsequently, 7.30 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%.

[0153] Next, 146 mmol of dimethyldichlorosilane was added as a bifunctional coupling agent, and the mixture was mixed to couple a portion of the styrene-isoprene diblock 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.

[0154] Thereafter, 1.41 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 (third polymerization stage). The polymerization conversion of styrene at this time was 100%.

[0155] Finally, 533 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.

[0156] (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 under the same conditions as in Example 1. A portion of the obtained solution containing the hydrogenated block copolymer composition was then taken out and subjected to the various measurements in the same manner as in Example 1. The results are summarized in Table 2.

[0157] (3) Recovery of Hydrogenated Block Copolymer Composition Using the obtained solution containing the hydrogenated block copolymer composition, the hydrogenated block copolymer composition was recovered and measured in the same manner as in Example 1. The results are shown in Table 2.

[0158] (4) Production of Foam Using the obtained hydrogenated block copolymer composition, a foam was produced and measured in the same manner as in Example 1. The results are summarized in Table 2.

[0159] Example 6 A foam was produced in the same manner as in Example 1, except that 2706 mmol of ethylene glycol dibutyl ether was used instead of dibutyl ether. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2.

[0160] Comparative Example 1 A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2. In Comparative Example 1, the fourth polymerization stage was not carried out.

[0161] Comparative Example 2 A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1 and that the hydrogenation reaction was not carried out. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2.

[0162] Comparative Example 3 A foam was produced in the same manner as in Example 1, except that the amounts of each reagent used in the reaction were changed as shown in Table 1. Measurements and evaluations were also carried out in the same manner as in Example 1. The results are summarized in Table 2. In Comparative Example 3, the fourth polymerization stage was not carried out.

[0163]

[0164]

[0165] As shown in Table 2, a foam obtained by foaming 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) in a weight ratio of A / B of 10 / 90 to 80 / 20, and in which the olefin hydrogenation rate in the polymer components constituting the hydrogenated block copolymer composition is 10 to 100%, exhibits an initial elastic modulus E ０ is low, and the compressive stress σ at a strain of 0.4 ０．４ and strain ε at compressive stress of 1 MPa １ＭＰａ The results were excellent in shock absorption and shock resistance (Examples 1 to 6).

[0166] On the other hand, when the hydrogenated block copolymer A represented by the general formula (A) was not contained, it was not possible to achieve both a low initial modulus and excellent shock-absorbing properties (Comparative Examples 1 and 3). Also, when the hydrogenation rate of the olefin was less than 10%, the compressive stress σ at a strain of 0.4 was ０．４ is too small, and the strain ε１ＭＰａ was too large, resulting in poor cushioning properties (Comparative Example 2).

Claims

1. A foam obtained by foaming 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): the weight ratio (A / B) of the hydrogenated block copolymer A to the hydrogenated block copolymer B is 10 / 90 to 80 / 20; A foam in which the hydrogenation rate of olefin in the polymer components constituting the hydrogenated block copolymer composition is 10 to 100%. 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 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 2.6 to 66, 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. 2. The foam according to claim 1, wherein the proportion of aromatic vinyl monomer units in all repeating units of the polymer components constituting the hydrogenated block copolymer composition is 10 to 75% by weight.

3. In the above general formula (A) and general formula (B), HD ａ and HD ｂ 3. The foam according to claim 1, wherein the vinyl bond content of each of the above is 1 to 80 mol %.

4. In the above general formula (A) and general formula (B), Ar1 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 ｂ 3. The foam according to claim 1, wherein the weight average molecular weight of each of the above is in the range of 10,000 to 300,000.

5. 3. The foam according to claim 1, wherein the weight ratio of the total of the hydrogenated block copolymer A and the hydrogenated block copolymer B in the polymer components constituting the hydrogenated block copolymer composition is 30 to 100% by weight.

6. 3. The foam according to claim 1, wherein the weight average molecular weight of all polymer components constituting the hydrogenated block copolymer composition is 30,000 to 400,000.

7. Apparent density is 0.1 to 0.7 g / cm ３ 3. The foam according to claim 1 or 2, wherein

8. A cushioning material comprising the foam according to claim 1 or 2.