Elastomer composition, elastomer sheet, composite sheet, and stretchable member

Abstract

Provided is an elastomer composition for forming an elastomer sheet constituting a composite sheet comprising a substrate and an elastomer sheet laminated on the substrate, wherein: the composite sheet is obtained by bonding the elastomer sheet to the substrate while the elastomer sheet is being stretched by 5-50%; the tensile elongation of the composite sheet is at most 20% when a tensile test is performed under conditions of a load of 2.5 N, a specimen width of 50 mm, and a temperature of 23 °C in the extension direction during bonding; and the elastomer composition contains 15-100 wt% of a polyolefin-based elastomer and 0-85 wt% of an aromatic vinyl-based block copolymer, the polyolefin-based elastomer having a Shore A hardness of 40-75, and the aromatic vinyl monomer unit content of the aromatic vinyl-based block copolymer being 8-25 wt%.

Description

Elastomer composition, elastomer sheet, composite sheet and elastic member

[0001] The present invention relates to an elastomer composition, an elastomer sheet, a composite sheet, and an elastic member.

[0002] Hygiene products such as disposable diapers and sanitary products are required to be able to follow the wearer's movements and fit well, and each part of them uses an elastic member made by laminating a base material, an elastic body, and a base material in this order.

[0003] For example, Patent Document 1 discloses an ultrasonic sealing device for manufacturing an elastic member as shown in Figure 24. Patent Document 1 also discloses that in the ultrasonic sealing device, when forming a sheet joint 40, a first sheet layer 20A, an elastic film 30, and a second sheet layer 20B are fed between an anvil roll 60 having protrusions 60a formed on its outer surface in the pattern of the sheet joint 40 and an ultrasonic horn 61. Patent Document 1 further discloses that, at this time, the elastic film 30 is stretched in the MD direction (machine direction, flow direction) to a predetermined elongation rate, and that the elongation rate of this elastic film 30 can be, for example, approximately 300% to 500%.

[0004] International Publication No. 2019 / 065575

[0005] As a packaging method for sheet-like products, roll packaging, in which the product is wound into a roll and packaged, is preferred because it offers excellent packaging stability and productivity, excellent handling properties, and the ability to store the package in a small space. However, when a roll package of an elastic member obtained using the method described in Patent Document 1 is stored for a long period of time, the elastic member stretches out and becomes unusable as an elastic member. Therefore, such elastic members are typically packaged by folding and stacking, but this type of package has the problems of poor handling and difficulty in storing in a small space. Alternatively, roll packaging can be performed by applying a weak tension to prevent the elastic member from stretching out, but this type of loosely wound package is prone to elastic member misalignment. Furthermore, the length of elastic member that can be packaged per roll is reduced, resulting in increased roll replacement frequency and increased workload.

[0006] The present invention has been made in consideration of the above circumstances, and aims to provide an elastomer composition that is a composite sheet that is suitably used for manufacturing elastic members, can provide a composite sheet that is suitable for roll packaging, and has excellent moldability.

[0007] The present inventors have conducted research to achieve the above object, and have found that the above object can be achieved by incorporating a polyolefin elastomer having a Shore A hardness within a limited range of 40 to 75 in an elastomer composition for forming a specific composite sheet for use in producing elastic members, and, if necessary, incorporating a limited amount of an aromatic vinyl block copolymer having an aromatic vinyl monomer unit content of 8 to 25% by weight, thereby completing the present invention.

[0008] That is, according to the present invention, the following elastomer composition is provided.

[0009] [1] An elastomer composition for forming an elastomer sheet that constitutes a composite sheet including a substrate and an elastomer sheet laminated on the substrate, wherein the composite sheet is formed by adhering the elastomer sheet to the substrate in a state in which the elastomer sheet is elongated by 5 to 50%, and the tensile elongation of the composite sheet is 20% or less when a tensile test is conducted in the elongation direction at the time of adhesion under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C, the elastomer composition containing 15 to 100% by weight of a polyolefin elastomer and 0 to 85% by weight of an aromatic vinyl block copolymer, the polyolefin elastomer having a Shore A hardness of 40 to 75, and the aromatic vinyl block copolymer having an aromatic vinyl monomer unit content of 8 to 25% by weight. [2] The elastomer composition according to [1], wherein the composite sheet is formed into an elastic member by stretching the substrate while machining it, and the tensile elongation of the elastic member is 100% or more in the elongation direction during bonding, as measured under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C. [3] The elastomer composition according to [1] or [2], wherein the tensile elongation of the substrate is 10% or less, as measured under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 25°C. [4] The elastomer composition according to any one of [1] to [3], wherein the composite sheet comprises a first substrate and a second substrate as the substrates, and wherein the composite sheet is a laminate formed by laminating the first substrate, the elastomer sheet, and the second substrate in this order. [5] The elastomer composition according to any one of [1] to [4], wherein the aromatic vinyl block copolymer is an aromatic vinyl-conjugated diene block copolymer. [6] The elastomer composition according to any one of [1] to [5], wherein the aromatic vinyl block copolymer contains a multi-branched unit having three or more branches. [7] The elastomer composition according to any one of [1] to [6], wherein the polyolefin elastomer contains an ethylene unit. [8] The elastomer composition according to [7], wherein the polyolefin elastomer further contains a propylene unit or an octene unit.[9] The elastomer composition according to any one of [1] to [8], wherein the weight average molecular weight of the aromatic vinyl block copolymer is 30,000 to 800,000.

[0010] The present invention also provides an elastomer sheet, a composite sheet, and an elastic member obtained using the above elastomer composition.

[0011]

[10] An elastomer sheet formed from the elastomer composition according to any one of [1] to [9].

[11] The elastomer sheet according to

[10] , which is an extrusion molded product of the elastomer composition.

[12] The elastomer sheet according to

[10] or

[11] , which has a thickness of 0.005 to 1 mm.

[13] A composite sheet comprising a substrate and the elastomer sheet according to any one of

[10] to

[12] laminated on the substrate, wherein the elastomer sheet is bonded to the substrate in a state of being elongated by 5 to 50%, and wherein the composite sheet has a tensile elongation of 20% or less in a tensile test in the elongation direction at the time of bonding under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C.

[14] The composite sheet according to

[13] , wherein the substrate is a nonwoven fabric.

[15] An elastic member obtained by stretching the composite sheet according to

[13] or

[14] while subjecting the substrate to mechanical processing, wherein the elastic member has a tensile elongation of 100% or more in the elongation direction during bonding, measured under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C.

[0012] According to the present invention, a composite sheet suitable for use in producing an elastic member, suitable for roll packaging, and an elastomer composition with excellent moldability can be provided.

[0013] Fig. 1 is a schematic diagram of a manufacturing apparatus for manufacturing a composite sheet according to an embodiment of the present disclosure. Fig. 2 is a schematic diagram (2a) of a convex pattern on the outer peripheral surface of an anvil roll used in the examples, and an enlarged view (2b) of the pattern.

[0014] In the present disclosure, the composite sheet is formed by adhering an elastomer sheet to a substrate in a state of being stretched by 5 to 50%, and when a tensile test is conducted in the elongation direction during adhesion under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C, the tensile elongation is 20% or less.

[0015] The test load (2.5 N / 50 mm width) in the tensile test is a simulated load applied to the composite sheet when wound into a roll, and the tensile elongation value is a numerical value that represents the extent to which the composite sheet elongates when wound into a roll. The smaller the tensile elongation value, the less the composite sheet elongates when wound into a roll, and the better the storage stability of the roll package (specifically, the less defects such as dimensional changes, stretching, and breakage of the composite sheet during storage). Therefore, the smaller the tensile elongation value, the more suitable the composite sheet is for roll packaging.

[0016] In the present disclosure, the composite sheet is stretched while being machined to form an elastic member. In the present disclosure, the elastic member has a tensile elongation of 100% or more in the elongation direction when bonded, measured under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C.

[0017] <Elastomer Composition> The elastomer composition of the present disclosure is an elastomer composition for forming the elastomer sheet that constitutes the above-described composite sheet, and contains 15 to 100 wt % of a polyolefin-based elastomer having a Shore A hardness of 40 to 75, and 0 to 85 wt % of an aromatic vinyl-based block copolymer having an aromatic vinyl monomer unit content of 8 to 25 wt %.

[0018] The elastomer composition of the present disclosure contains a polyolefin-based elastomer having a Shore A hardness within a limited range of 40 to 75, and optionally contains a limited amount of an aromatic vinyl-based block copolymer having an aromatic vinyl monomer unit content of 8 to 25 wt %. By virtue of this configuration, the elastomer composition of the present disclosure can provide a composite sheet that exhibits low elongation when wound into a roll and has excellent storage stability for roll packages, while also imparting excellent stretchability (particularly flexibility, recovery, and resistance to full stretch) to the resulting elastic member. Furthermore, by virtue of the above-described configuration, the elastomer composition of the present disclosure also exhibits excellent moldability, exhibits low pulsation during melt molding (so-called draw resonance), and allows for stable molding over long periods of time.

[0019] [Polyolefin-Based Elastomer] The elastomer composition of the present disclosure contains 15 to 100 wt % of a polyolefin-based elastomer having a Shore A hardness of 40 to 75.

[0020] The polyolefin-based elastomer content in the elastomer composition of the present disclosure is 15 to 100 wt %. If the polyolefin-based elastomer content is too low, the elastomer sheet in the resulting composite sheet will be prone to excessive recovery, resulting in significant elongation of the composite sheet when wound into a roll. For example, even when the elastomer composition of the present disclosure is melt-molded into a sheet and then stretched and bonded to a substrate immediately thereafter, an elastomer composition with too low a polyolefin-based elastomer content is less likely to undergo plastic deformation, and the elastomer sheet will be prone to excessive recovery after being bonded to the substrate. The polyolefin-based elastomer content is not particularly limited, but is preferably 18 to 85 wt %, more preferably 18 to 75 wt %, from the viewpoint of further enhancing the effects of the present disclosure. Furthermore, from the viewpoint of further improving moldability, the storage stability of the resulting composite sheet, and the stretchability of the resulting stretchable material, the content of the polyolefin-based elastomer is preferably 20 to 60% by weight, more preferably 20 to 50% by weight, even more preferably 20 to 40% by weight, and particularly preferably 25 to 35% by weight.

[0021] The Shore A hardness of the polyolefin elastomer used in the present disclosure is not limited as long as it is 40 to 75, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 45 to 72, and more preferably 50 to 70. Furthermore, from the viewpoint of further greatly enhancing the stretchability of the resulting stretchable material, the Shore A hardness is preferably 55 to 70, more preferably 60 to 69, and even more preferably 63 to 68. The Shore A hardness is measured in accordance with JIS K 6253.

[0022] The polyolefin-based elastomer is not particularly limited as long as it is a thermoplastic resin having an olefin as the main repeating unit, and may be any of a homopolymer of an α-olefin, a copolymer of two or more kinds of α-olefins, and a copolymer of an α-olefin and a monomer other than an α-olefin, or may be a modified (co)polymer of any of these.

[0023] When the polyolefin elastomer contains two or more types of monomer units, the polymerization mode of the two or more types of monomers is not particularly limited, and may be a known copolymerization mode such as random copolymerization, block copolymerization, graft copolymerization, or a combination thereof. When the polyolefin elastomer contains two or more types of monomer units, it is preferably a random copolymer or a block copolymer, and more preferably a random copolymer or a multiblock copolymer.

[0024] Specific examples of polyolefin elastomers include homopolymers of α-olefins such as ethylene, propylene, and octene, such as polyethylenes such as linear low-density polyethylene (LLDPE), low-density polyethylene (LDPE), medium-density polyethylene (MDPE), high-density polyethylene (HDPE), and metallocene polyethylene, polypropylene, metallocene polypropylene, polymethylpentene, and polybutene; copolymers of ethylene and other α-olefins, such as ethylene-propylene random copolymers, ethylene-propylene block copolymers, ethylene-butene-1 copolymers, ethylene-propylene-butene-1 copolymers, ethylene-octene copolymers, and ethylene-cyclic olefin copolymers; copolymers of α-olefins and carboxylic acid unsaturated alcohols, mainly containing α-olefins, and saponified products thereof, such as ethylene copolymers. Examples of the copolymer include ethylene-vinyl acetate copolymers and ethylene-vinyl alcohol copolymers; copolymers of α-olefins, primarily α-olefins, with α,β-unsaturated carboxylic acid esters or α,β-unsaturated carboxylic acids, such as ethylene-α,β-unsaturated carboxylic acid ester copolymers (ethylene-ethyl acrylate copolymers, ethylene-methyl methacrylate copolymers, etc.) and ethylene-α,β-unsaturated carboxylic acid copolymers (ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, etc.); acid-modified olefin resins obtained by modifying α-olefin (co)polymers such as polyethylene and polypropylene with unsaturated carboxylic acids and / or anhydrides thereof, such as acrylic acid, methacrylic acid, maleic acid, maleic anhydride, fumaric acid, and itaconic acid; ionomer resins obtained by reacting ethylene and methacrylic acid copolymers with Na ions, Zn ions, etc.; and mixtures thereof.

[0025] As the polyolefin-based elastomer, from the viewpoint of further enhancing the effects of the present disclosure, one containing an ethylene unit is preferable, a copolymer containing an ethylene unit and another α-olefin unit is more preferable, a copolymer containing an ethylene unit and a propylene unit or an octene unit is even more preferable, and a copolymer containing an ethylene unit and a propylene unit is particularly preferable.

[0026] When the polyolefin-based elastomer contains ethylene units, the content of the ethylene units is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 4 to 100% by weight, more preferably 6 to 75% by weight, and even more preferably 8 to 60% by weight. Furthermore, from the viewpoint of further greatly enhancing the stretchability of the resulting stretchable material, the content of the ethylene units is preferably 10 to 30% by weight, more preferably 12 to 25% by weight, and even more preferably 14 to 20% by weight.

[0027] When the polyolefin elastomer contains propylene units, the content of the propylene units is not particularly limited, but is preferably 96% by weight or less, more preferably 25 to 94% by weight, and even more preferably 40 to 92% by weight. Furthermore, from the viewpoint of being able to further greatly increase the stretchability of the resulting stretchable material, the content of the propylene units is preferably 70 to 90% by weight, more preferably 75 to 88% by weight, and even more preferably 80 to 86% by weight.

[0028] When the polyolefin elastomer contains octene units, the content of the octene units is not particularly limited, but is preferably 96 wt% or less, more preferably 25 to 94 wt%, even more preferably 40 to 92 wt%, particularly preferably 40 to 60 wt%, and most preferably 42 to 50 wt%. When the content of the octene units is within the above range, the effects of the present disclosure can be further enhanced.

[0029] The weight average molecular weight of the polyolefin elastomer is not particularly limited, but is usually 10,000 to 5,000,000, preferably 50,000 to 800,000, more preferably 80,000 to 400,000, and even more preferably 100,000 to 300,000. When the weight average molecular weight is within the above range, the effects of the present disclosure can be further enhanced.

[0030] The density of the polyolefin elastomer is not particularly limited, but is usually 0.80 to 0.95 g / cm ３and preferably 0.82 to 0.92 g / cm ３ and more preferably 0.84 to 0.90 g / cm ３ and more preferably 0.85 to 0.88 g / cm ３ When the density is within the above range, the effects of the present disclosure can be further enhanced.

[0031] The storage modulus of the polyolefin elastomer at 23°C is not particularly limited, but is preferably 0.1 x 10 ６ ~40 x 10 ６ Pa, and more preferably 0.3×10 ６ ~15 x 10 ６ Pa, and more preferably 1.0 × 10 ６ ~8 x 10 ６ Pa, and more preferably 1.5×10 ６ ~4 x 10 ６ When the storage modulus at 23° C. is within the above range, the effects of the present disclosure can be further enhanced.

[0032] The loss modulus of the polyolefin elastomer at 23°C is not particularly limited, but is preferably 0.1 x 10 ５ ~30 x 10 ５ Pa, and more preferably 0.3×10 ５ ~10 x 10 ５ Pa, and more preferably 1.0 × 10 ５ ~6 x 10 ５ Pa, and more preferably 1.5×10 ５ ~3 x 10 ５ When the loss modulus at 23°C is within the above range, the effects of the present disclosure can be further enhanced.

[0033] The melting point of the polyolefin-based elastomer is not particularly limited, but is preferably 60 to 200° C., and more preferably 90 to 150° C. If the melting point is within the above range, the effects of the present disclosure can be further enhanced.

[0034] The Vicat softening point of the polyolefin elastomer is not particularly limited, but is preferably 20 to 100° C., and more preferably 40 to 80° C. If the Vicat softening point is within the above range, the effects of the present disclosure can be further enhanced.

[0035] The melt index of the polyolefin elastomer is not particularly limited, but is typically 0.1 to 1000 g / 10 min as measured in accordance with ASTM D-1238 (G conditions, 200°C, 5 kg). The melt index is preferably 1 to 100 g / 10 min, more preferably 2 to 30 g / 10 min, and even more preferably 3 to 19 g / 10 min. When the melt index is within the above range, the effects of the present disclosure can be further enhanced.

[0036] [Aromatic Vinyl Block Copolymer] The elastomer composition of the present disclosure contains 0 to 85 wt % of an aromatic vinyl block copolymer having an aromatic vinyl monomer unit content of 8 to 25 wt %.

[0037] The content of the aromatic vinyl block copolymer in the elastomer composition of the present disclosure is not particularly limited as long as it is 0 to 85% by weight, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 15 to 82% by weight, and more preferably 25 to 82% by weight. Furthermore, from the viewpoint of further improving moldability, the storage stability of the resulting composite sheet, and the stretchability and stress relaxation properties of the resulting elastic member, the content of the aromatic vinyl block copolymer is preferably 40 to 80% by weight, more preferably 50 to 80% by weight, even more preferably 60 to 80% by weight, and particularly preferably 65 to 75% by weight.

[0038] The aromatic vinyl block copolymer is not particularly limited as long as it contains one or more aromatic vinyl polymer blocks and satisfies the above-mentioned content of aromatic vinyl monomer units. In the present disclosure, it is preferable to use an aromatic vinyl block copolymer composition containing two or more aromatic vinyl block copolymers as the aromatic vinyl block copolymer. In this case, it is sufficient that the content of aromatic vinyl monomer units relative to the entire aromatic vinyl block copolymer composition is within the above-mentioned range.

[0039] The content of aromatic vinyl monomer units in the aromatic vinyl block copolymer (the content of aromatic vinyl monomer units relative to the entire aromatic vinyl block copolymer composition) is not particularly limited as long as it is 8 to 25% by weight, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 12 to 24% by weight, more preferably 14 to 21% by weight, and even more preferably 16 to 20% by weight.

[0040] The content of the aromatic vinyl monomer unit can be determined based on the ratio of the detected intensities measured by a differential refractometer and an ultraviolet detector in high performance liquid chromatography.

[0041] The aromatic vinyl polymer block constituting the aromatic vinyl block copolymer is a polymer block composed mainly of repeating units, which are aromatic vinyl monomer units obtained by polymerizing an aromatic vinyl monomer. The aromatic vinyl monomer used to form the aromatic vinyl monomer units of the aromatic vinyl polymer block is not particularly limited as long as it is an aromatic vinyl compound. Specific examples of aromatic vinyl monomers include styrene, α-methylstyrene, 2-methylstyrene, 3-methylstyrene, 4-methylstyrene, 2-ethylstyrene, 3-ethylstyrene, 4-ethylstyrene, 2,4-diisopropylstyrene, 2,4-dimethylstyrene, 4-t-butylstyrene, 5-t-butyl-2-methylstyrene, 2-chlorostyrene, 3-chlorostyrene, 4-chlorostyrene, 4-bromostyrene, 2-methyl-4,6-dichlorostyrene, 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.

[0042] The aromatic vinyl polymer block may contain other monomer units as long as the aromatic vinyl monomer units are the main repeating units. Examples of monomers constituting the monomer units other than aromatic vinyl monomer units include conjugated diene monomers such as 1,3-butadiene and isoprene (2-methyl-1,3-butadiene), α,β-unsaturated nitrile monomers, unsaturated carboxylic acid or acid anhydride monomers, unsaturated carboxylic acid ester monomers, and non-conjugated diene monomers. The content of monomer units other than aromatic vinyl monomer units in the 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. That is, the aromatic vinyl polymer block is preferably composed essentially of one or more aromatic vinyl monomer units, and particularly preferably of styrene units.

[0043] The weight average molecular weight of the aromatic vinyl polymer block is preferably 6,000 to 40,000, more preferably 7,000 to 20,000, even more preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0044] The aromatic vinyl block copolymer is preferably an aromatic vinyl-conjugated diene block copolymer containing one or more aromatic vinyl polymer blocks and one or more conjugated diene blocks.

[0045] The conjugated diene polymer block is a polymer block composed of conjugated diene monomer units obtained by polymerizing a conjugated diene monomer as the main repeating unit. The conjugated diene monomer used to constitute the conjugated diene monomer units of the conjugated diene polymer block is not particularly limited as long as it is a conjugated diene compound. Examples of conjugated diene monomers include 1,3-butadiene, isoprene, 2,3-dimethyl-1,3-butadiene, 2-chloro-1,3-butadiene, 1,3-pentadiene, 1,3-hexadiene, myrcene, and farnesene. Among these, 1,3-butadiene and / or isoprene are preferred, and isoprene is particularly preferred. These conjugated diene monomers can be used alone or in combination of two or more. Furthermore, a hydrogenation reaction may be performed on some of the unsaturated bonds of the conjugated diene polymer block.

[0046] The conjugated diene polymer block may contain other monomer units as long as the conjugated diene monomer units are the main repeating units. Examples of monomers constituting the monomer units other than the conjugated diene monomer units 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. The content of monomer units other than the conjugated diene monomer units in the conjugated diene polymer block is preferably 20% by weight or less, more preferably 10% by weight or less, and particularly preferably substantially 0% by weight. That is, the conjugated diene polymer block is preferably composed essentially of one or more types of conjugated diene monomer units, and particularly preferably of isoprene units.

[0047] The weight average molecular weight of the conjugated diene polymer block is preferably 20,000 to 600,000, more preferably 30,000 to 400,000, even more preferably 40,000 to 320,000, particularly preferably 50,000 to 280,000, and most preferably 60,000 to 240,000.

[0048] The vinyl bond content of the conjugated diene polymer block (the proportion of 1,2-vinyl bond units and 3,4-vinyl bond units in all conjugated diene monomer units in the conjugated diene polymer block) is not particularly limited, but is preferably 1 to 20 mol %, more preferably 3 to 15 mol %, and particularly preferably 5 to 10 mol %. When the vinyl bond content is within the above range, the stretchability of the resulting stretchable material can be further improved.

[0049] The vinyl bond content of the conjugated diene polymer block was measured using deuterated chloroform as the solvent. １ It can be determined based on H-NMR measurement.

[0050] When an aromatic vinyl block copolymer contains multiple aromatic vinyl polymer blocks, the monomer compositions and weight-average molecular weights of the multiple aromatic vinyl polymer blocks may be equal to or different from one another, but are preferably substantially equal. When an aromatic vinyl block copolymer contains multiple conjugated diene polymer blocks, the monomer compositions, vinyl bond contents, and weight-average molecular weights of the multiple conjugated diene polymer blocks may be equal to or different from one another, but are preferably substantially equal. In the present disclosure, "two characteristic values ​​being substantially equal" means that the ratio of one characteristic value to the other is within a range of 0.95 to 1.05, and preferably the ratio of one characteristic value to the other is within a range of 0.98 to 1.02.

[0051] The weight average molecular weight of the aromatic vinyl block copolymer (weight average molecular weight of the entire aromatic vinyl block copolymer composition) is not particularly limited, but is preferably 30,000 to 800,000, more preferably 60,000 to 600,000, even more preferably 90,000 to 500,000, particularly preferably 120,000 to 400,000, and most preferably 160,000 to 300,000.

[0052] In the present invention, the weight average molecular weight of each polymer block and the weight average molecular weight of each block polymer are determined as polystyrene-equivalent values ​​measured by high performance liquid chromatography.

[0053] In addition, when an aromatic vinyl block copolymer is substantially composed of only aromatic vinyl monomer units and conjugated diene monomer units, the block copolymer 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 are decomposed and the aromatic monovinyl monomer unit portions can be isolated, and the weight-average molecular weight of the styrene polymer block can be measured by this method.

[0054] The weight-average molecular weight of each polymer block and the weight-average molecular weight of each block polymer can be adjusted by adjusting the amount of each monomer used to form each polymer block and the amount of polymerization initiator used when obtaining a block copolymer by polymerization reaction.

[0055] The melt index of the aromatic vinyl block copolymer is not particularly limited, but is typically 0.1 to 1000 g / 10 min as measured in accordance with ASTM D-1238 (G conditions, 200°C, 5 kg). The melt index is preferably 1 to 100 g / 10 min, more preferably 2 to 30 g / 10 min, and even more preferably 3 to 19 g / 10 min. When the melt index is within the above range, the effects of the present disclosure can be further enhanced.

[0056] Specific examples of the aromatic vinyl block copolymer include block copolymers (A) to (E) represented by the following general formulas (A) to (E).

[0057] General formula (A): Ar1 ａ -D ａ -Ar2 ａ (In the formula, Ar1 ａ and Ar2 ａ are aromatic vinyl polymer blocks having a weight average molecular weight of 5,000 to 20,000, and D ａ represents a conjugated diene polymer block)

[0058] General formula (B): Ar ｂ -D ｂ (In the formula, Ar ｂ is an aromatic vinyl polymer block having a weight average molecular weight of 5,000 to 20,000; D ｂ represents a conjugated diene polymer block)

[0059] General formula (C): (Ar ｃ -D ｃ ) ３ -X (wherein, Ar ｃ is an aromatic vinyl polymer block, D ｃ represents a conjugated diene polymer block, and X represents a residue of a coupling agent.

[0060] General formula (D): (Ar ｄ -D ｄ ) ４ -X (wherein, Ar ｄ is an aromatic vinyl polymer block, D ｄ represents a conjugated diene polymer block, and X represents a residue of a coupling agent.

[0061] General formula (E): Ar1 ｅ -D ｅ -Ar2 ｅ (In the formula, Ar1 ｅ is an aromatic vinyl polymer block having a weight average molecular weight of 5,000 to 20,000; D ｅ is a conjugated diene polymer block, Ar2 ｅ represents an aromatic vinyl polymer block having a weight average molecular weight of more than 20,000 and not more than 400,000.

[0062] The monomer composition of the aromatic vinyl polymer block in the general formulae (A) to (E) is preferably the same as the monomer composition of the aromatic vinyl polymer block described above. Also, the monomer composition and vinyl bond content of the conjugated diene polymer block in the general formulae (A) to (E) are preferably the same as the monomer composition and vinyl bond content of the conjugated diene polymer block described above.

[0063] (Block Copolymer (A)) The block copolymer (A) is a copolymer represented by the following general formula (A): General formula (A): Ar1 ａ -D ａ -Ar2 ａ (In the formula, Ar1 ａ and Ar2 ａ are aromatic vinyl polymer blocks having a weight average molecular weight of 5,000 to 20,000, and D ａ represents a conjugated diene polymer block)

[0064] Aromatic vinyl polymer block (Ar1 ａ ) and an aromatic vinyl polymer block (Ar2 ａ The monomer composition and weight average molecular weight of each of the copolymers may be equal to or different from each other, but are preferably substantially equal to each other.

[0065] Aromatic vinyl polymer block (Ar1 ａ ) and an aromatic vinyl polymer block (Ar2 ａ ) each has a weight average molecular weight of 5,000 to 20,000, preferably 6,000 to 18,000, more preferably 7,000 to 16,000, even more preferably 8,000 to 15,000, particularly preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0066] Conjugated diene polymer block (D ａ The weight average molecular weight of the copolymer is preferably 40,000 to 400,000, more preferably 80,000 to 320,000, even more preferably 100,000 to 280,000, and particularly preferably 120,000 to 240,000.

[0067] The weight average molecular weight of the block copolymer (A) is preferably 50,000 to 450,000, more preferably 90,000 to 350,000, still more preferably 120,000 to 300,000, and particularly preferably 150,000 to 250,000.

[0068] The content of the aromatic vinyl monomer units in the block copolymer (A) is preferably 8 to 25% by weight, more preferably 12 to 24% by weight, even more preferably 14 to 21% by weight, and particularly preferably 16 to 20% by weight, based on the total monomer units constituting the block copolymer (A).

[0069] Specific examples of the block copolymer (A) include a block copolymer (A1) represented by the general formula (A1) described later and a block copolymer (A2) represented by the general formula (A2) described later.

[0070] (Block Copolymer (A1)) The block copolymer (A1) is a copolymer represented by the following general formula (A1): General formula (A1): Ar1 ａ１ -D ａ１ -Ar2 ａ１ (In the formula, Ar1ａ１ and Ar2 ａ１ are aromatic vinyl polymer blocks having a weight average molecular weight of 5,000 to 20,000, and D ａ１ represents a conjugated diene polymer block that is substantially free of residues of a coupling agent)

[0071] Aromatic vinyl polymer block (Ar1 ａ１ ) and an aromatic vinyl polymer block (Ar2 ａ１ ) are the aromatic vinyl polymer blocks (Ar1) in the general formula (A), respectively. ａ ) and (Ar2 ａ ) corresponds to the conjugated diene polymer block (D ａ１ ) is the conjugated diene polymer block (D ａ ) corresponds to

[0072] Conjugated diene polymer block (D ａ１ The weight average molecular weight of the copolymer (II) is preferably 40,000 to 600,000, more preferably 60,000 to 400,000, even more preferably 80,000 to 320,000, particularly preferably 100,000 to 280,000, and most preferably 120,000 to 240,000.

[0073] The block copolymer (A1) is preferably one obtained by a production method in which a polymer block is formed by sequentially polymerizing an aromatic vinyl monomer, a conjugated diene monomer, and then an aromatic vinyl monomer in this order.

[0074] (Block Copolymer (A2)) The block copolymer (A2) is a copolymer represented by the following general formula (A2): General formula (A2): (Ar ａ２ -D ａ２ ) ２ -X (wherein, Ar ａ２ is an aromatic vinyl polymer block having a weight average molecular weight of 5,000 to 20,000; D ａ２ represents a conjugated diene polymer block, and X represents a residue of a coupling agent.

[0075] The block copolymer (A2) is a copolymer of two diblock copolymers (Arａ２ -D ａ２ ) are bonded to each other (Ar ａ２ -D ａ２ -X-D ａ２ -Ar ａ２ ) Aromatic vinyl polymer block (Ar ａ２ ) is the aromatic vinyl polymer block (Ar1) in general formula (A). ａ ) and (Ar2 ａ ) and two conjugated diene polymer blocks (D ａ２ ) is bonded via a residue of a coupling agent (X) ａ２ -X-D ａ２ ) represents the conjugated diene polymer block D in the general formula (A). ａ Corresponds to.

[0076] The block copolymer (A2) has a plurality of conjugated diene polymer blocks (D ａ２ The monomer composition, vinyl bond content and weight average molecular weight of the copolymer (A), (B), (C), (D), (E), (F), (G), (H), (I), (Il), (Il) may be the same or different from each other, but are preferably substantially the same.

[0077] Conjugated diene polymer block (D ａ２ The weight average molecular weight of the copolymer (II) is preferably 20,000 to 300,000, more preferably 30,000 to 200,000, even more preferably 40,000 to 160,000, particularly preferably 50,000 to 140,000, and most preferably 60,000 to 120,000.

[0078] The residue of the coupling agent (X) is preferably a residue of a silicon atom-containing coupling agent, more preferably a residue of a halogenated silane or an alkoxysilane. Examples of the coupling agent constituting the residue of the coupling agent (X) are preferably bifunctional coupling agents, among those described below.

[0079] The block copolymer (A2) is preferably one obtained by a production method in which an aromatic vinyl monomer and a conjugated diene monomer are polymerized to form a diblock chain, and the diblock chain is then reacted with a coupling agent to perform coupling.

[0080] (Block Copolymer (B)) The block copolymer (B) is a copolymer represented by the following general formula (B): General formula (B): Ar ｂ -D ｂ (In the formula, Ar ｂ is an aromatic vinyl polymer block having a weight average molecular weight of 5,000 to 20,000; D ｂ represents a conjugated diene polymer block)

[0081] Aromatic vinyl polymer block (Ar ｂ The weight average molecular weight of the copolymer is 5,000 to 20,000, preferably 6,000 to 18,000, more preferably 7,000 to 16,000, even more preferably 8,000 to 15,000, particularly preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0082] When the aromatic vinyl block copolymer composition contains the block copolymer (A) in addition to the block copolymer (B), the aromatic vinyl polymer block (Ar ｂ The weight average molecular weight of the aromatic vinyl polymer block (Ar1) of the block copolymer (A) is ａ and Ar2 ａ It is preferable that the weight average molecular weight is substantially equal to the weight average molecular weight of at least one of the above.

[0083] Conjugated diene polymer block (D ｂ The weight average molecular weight of the copolymer (II) is preferably 20,000 to 300,000, more preferably 30,000 to 200,000, even more preferably 40,000 to 160,000, particularly preferably 50,000 to 140,000, and most preferably 60,000 to 120,000.

[0084] When the aromatic vinyl block copolymer composition contains the block copolymer (A1) in addition to the block copolymer (B), the conjugated diene polymer block (D ｂ The weight average molecular weight of the conjugated diene polymer block (D ａ１ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0085] When the aromatic vinyl block copolymer composition contains the block copolymer (A2) in addition to the block copolymer (B), the conjugated diene polymer block (D ｂ The weight average molecular weight of the conjugated diene polymer block (D ａ２ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0086] The weight average molecular weight of the block copolymer (B) is preferably 20,000 to 300,000, more preferably 40,000 to 200,000, still more preferably 50,000 to 150,000, and particularly preferably 60,000 to 130,000.

[0087] The content of the aromatic vinyl monomer units in the block copolymer (B) is preferably 8 to 25% by weight, more preferably 12 to 24% by weight, even more preferably 14 to 21% by weight, and particularly preferably 16 to 20% by weight, based on the total monomer units constituting the block copolymer (B).

[0088] The block copolymer (B) is preferably one obtained by a production method in which an aromatic vinyl monomer and a conjugated diene monomer are sequentially polymerized in this order to form a polymer block.

[0089] (Block Copolymer (C)) The block copolymer (C) is a copolymer represented by the following general formula (C): General formula (C): (Ar ｃ -D ｃ ) ３ -X (wherein, Ar ｃ is an aromatic vinyl polymer block, D ｃ represents a conjugated diene polymer block, and X represents a residue of a coupling agent.

[0090] The block copolymer (C) is a copolymer of three diblock units (Ar ｃ -D ｃ ) have a structure in which they are bonded to each other.

[0091] The block copolymer (C) has a plurality of aromatic vinyl polymer blocks (Ar ｃThe monomer composition and weight average molecular weight of the conjugated diene polymer blocks (D) may be the same or different from each other, but are preferably substantially the same. ｃ The monomer composition, vinyl bond content and weight average molecular weight of the copolymer (A), (B), (C), (D), (E), (F), (G), (H), (I), (Il), (Il) may be the same or different from each other, but are preferably substantially the same.

[0092] Aromatic vinyl polymer block (Ar ｃ The weight average molecular weight of each of the copolymers is preferably 6,000 to 40,000, more preferably 7,000 to 20,000, even more preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0093] When the aromatic vinyl block copolymer composition contains the block copolymer (A) or (B) in addition to the block copolymer (C), the aromatic vinyl polymer block (Ar ｃ The weight average molecular weight of the aromatic vinyl polymer block (Ar ａ ) or (Ar ｂ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0094] Conjugated diene polymer block (D ｃ The weight average molecular weight of the copolymer (II) is preferably 20,000 to 300,000, more preferably 30,000 to 200,000, even more preferably 40,000 to 160,000, particularly preferably 50,000 to 140,000, and most preferably 60,000 to 120,000.

[0095] When the aromatic vinyl block copolymer composition contains the block copolymer (A2) or (B) in addition to the block copolymer (C), the conjugated diene polymer block (D ｃ The weight average molecular weight of the conjugated diene polymer block (D ａ２ ) or (D ｂ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0096] The residue of the coupling agent (X) is preferably a residue of a silicon atom-containing coupling agent, more preferably a residue of a halogenated silane or an alkoxysilane. Of the coupling agents constituting the residue of the coupling agent (X), preferred are trifunctional or tetrafunctional coupling agents, among those described below.

[0097] The weight average molecular weight of the block copolymer (C) is preferably 60,000 to 900,000, more preferably 120,000 to 600,000, still more preferably 150,000 to 450,000, and particularly preferably 180,000 to 390,000.

[0098] The content of the aromatic vinyl monomer units in the block copolymer (C) is preferably 8 to 25% by weight, more preferably 12 to 24% by weight, even more preferably 14 to 21% by weight, and particularly preferably 16 to 20% by weight, based on the total monomer units constituting the block copolymer (C).

[0099] The block copolymer (C) is preferably one obtained by a production method in which an aromatic vinyl monomer and a conjugated diene monomer are polymerized to form a diblock chain, and the diblock chain is reacted with a coupling agent to perform coupling.

[0100] (Block Copolymer (D)) The block copolymer (D) is a copolymer represented by the following general formula (D): General formula (D): (Ar ｄ -D ｄ ) ４ -X (wherein, Ar ｄ is an aromatic vinyl polymer block, D ｄ represents a conjugated diene polymer block, and X represents a residue of a coupling agent.

[0101] The block copolymer (D) is a copolymer of four diblock units (Ar ｄ -D ｄ ) have a structure in which they are bonded to each other.

[0102] The block copolymer (D) has a plurality of aromatic vinyl polymer blocks (Ar ｄThe monomer composition and weight average molecular weight of the conjugated diene polymer blocks (D) may be the same or different from each other, but are preferably substantially the same. ｄ The monomer composition, vinyl bond content and weight average molecular weight of the copolymer (A), (B), (C), (D), (E), (F), (G), (H), (I), (Il), (Il) may be the same or different from each other, but are preferably substantially the same.

[0103] Aromatic vinyl polymer block (Ar ｄ The weight average molecular weight of each of the copolymers is preferably 6,000 to 40,000, more preferably 7,000 to 20,000, even more preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0104] When the aromatic vinyl block copolymer composition contains the block copolymer (A), (B) or (C) in addition to the block copolymer (D), the aromatic vinyl polymer block (Ar ｄ The weight average molecular weight of the aromatic vinyl polymer block (Ar ａ ), (Ar ｂ ) or (Ar ｃ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0105] Conjugated diene polymer block (D ｄ The weight average molecular weight of the copolymer (II) is preferably 20,000 to 300,000, more preferably 30,000 to 200,000, even more preferably 40,000 to 160,000, particularly preferably 50,000 to 140,000, and most preferably 60,000 to 120,000.

[0106] When the aromatic vinyl block copolymer composition contains the block copolymer (A2), (B) or (C) in addition to the block copolymer (D), the conjugated diene polymer block (D ｄ The weight average molecular weight of the conjugated diene polymer block (D ａ２ ), (D ｂ ) or (D ｃ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0107] The residue of the coupling agent (X) is preferably a residue of a silicon atom-containing coupling agent, more preferably a residue of a halogenated silane or an alkoxysilane. Examples of the coupling agent constituting the residue of the coupling agent (X) are preferably tetrafunctional coupling agents, among those described below.

[0108] The weight average molecular weight of the block copolymer (D) is preferably 80,000 to 1,200,000, more preferably 160,000 to 800,000, still more preferably 200,000 to 600,000, and particularly preferably 240,000 to 520,000.

[0109] The content of the aromatic vinyl monomer units in the block copolymer (D) is preferably 8 to 25% by weight, more preferably 12 to 24% by weight, even more preferably 14 to 21% by weight, and particularly preferably 16 to 20% by weight, based on the total monomer units constituting the block copolymer (D).

[0110] The block copolymer (D) is preferably one obtained by a production method in which an aromatic vinyl monomer and a conjugated diene monomer are polymerized to form a diblock chain, and the diblock chain is reacted with a coupling agent to perform coupling.

[0111] (Block Copolymer (E)) The block copolymer (E) is a copolymer represented by the following general formula (E): General formula (E): Ar1 ｅ -D ｅ -Ar2 ｅ (In the formula, Ar1 ｅ is an aromatic vinyl polymer block having a weight average molecular weight of 5,000 to 20,000; D ｅ is a conjugated diene polymer block, Ar2 ｅ represents an aromatic vinyl polymer block having a weight average molecular weight of more than 20,000 and not more than 400,000.

[0112] The block copolymer (E) is an aromatic vinyl polymer block (Ar1) having a relatively small weight average molecular weight.ｅ ) and an aromatic vinyl polymer block (Ar2) having a relatively large weight average molecular weight ｅ ) and a conjugated diene polymer block (D ｅ ) is preferably substantially free of residues of coupling agents.

[0113] Aromatic vinyl polymer block (Ar1 ｅ ) and an aromatic vinyl polymer block (Ar2 ｅ The monomer compositions of the copolymers 1 and 2 may be the same or different from each other, but are preferably substantially the same.

[0114] Aromatic vinyl polymer block (Ar1 ｅ The weight average molecular weight of the copolymer is 5,000 to 20,000, preferably 6,000 to 18,000, more preferably 7,000 to 16,000, even more preferably 8,000 to 15,000, particularly preferably 8,000 to 16,000, particularly preferably 9,000 to 14,000, and most preferably 10,000 to 13,000.

[0115] When the aromatic vinyl block copolymer composition contains the block copolymer (A), (B), (C) or (D) in addition to the block copolymer (E), the aromatic vinyl polymer block (Ar1 ｅ The weight average molecular weight of the aromatic vinyl polymer block (Ar ａ ), (Ar ｂ ), (Ar ｃ ) or (Ar ｄ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0116] Aromatic vinyl polymer block (Ar2 ｅ The weight average molecular weight of the copolymer is more than 20,000 and not more than 400,000, more preferably 25,000 to 300,000, even more preferably 30,000 to 200,000, particularly preferably 35,000 to 150,000, and most preferably 40,000 to 100,000.

[0117] Aromatic vinyl polymer block (Ar1ｅ ) relative to the weight average molecular weight of the aromatic vinyl polymer block (Ar2 ｅ ) the ratio of weight average molecular weights (Ar2 ｅ / Ar1 ｅ ) is preferably 2 to 30, more preferably 2.5 to 20, even more preferably 3 to 15, and particularly preferably 4 to 10.

[0118] Conjugated diene polymer block (D ｅ The weight average molecular weight of the copolymer is preferably 40,000 to 600,000, more preferably 60,000 to 400,000, and even more preferably 80,000 to 200,000.

[0119] When the aromatic vinyl block copolymer composition contains the block copolymer (A1) in addition to the block copolymer (E), the conjugated diene polymer block (D ｅ The weight average molecular weight of the conjugated diene polymer block (D ａ１ ) is preferably substantially equal to the weight average molecular weight of the copolymer.

[0120] The weight average molecular weight of the block copolymer (E) is preferably 50,000 to 450,000, more preferably 90,000 to 350,000, and even more preferably 120,000 to 300,000.

[0121] The content of the aromatic vinyl monomer units in the block copolymer (E) is preferably 25 to 90% by weight, more preferably 35 to 80% by weight, and even more preferably 40 to 70% by weight, based on the total monomer units constituting the block copolymer (E).

[0122] The block copolymer (E) is preferably one obtained by a production method in which a polymer block is formed by sequentially polymerizing an aromatic vinyl monomer, a conjugated diene monomer, and then an aromatic vinyl monomer in this order.

[0123] From the viewpoint of further enhancing the effects of the present disclosure, the aromatic vinyl block copolymer preferably contains an aromatic vinyl-conjugated diene diblock copolymer (e.g., block copolymer (B)) or an aromatic vinyl-conjugated diene-aromatic vinyl triblock copolymer (e.g., block copolymer (A) or (E)).

[0124] The content of the aromatic vinyl-conjugated diene diblock copolymer in the aromatic vinyl block copolymer is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 0 to 35% by weight, more preferably 0 to 25% by weight, and even more preferably 0 to 20% by weight.

[0125] When the aromatic vinyl block copolymer contains an aromatic vinyl-conjugated diene-aromatic vinyl triblock copolymer, the content thereof is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 30 to 100% by weight, more preferably 40 to 90% by weight, even more preferably 45 to 80% by weight, and particularly preferably 50 to 75% by weight.

[0126] The aromatic vinyl block copolymer preferably contains a multi-branched copolymer having three or more branches (for example, block copolymer (C) or (D)) from the viewpoint of further improving moldability and further reducing elongation of the resulting composite sheet when wound into a roll.

[0127] The content of the multi-branched monomers having 3 or more branches in the aromatic vinyl block copolymer is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 5 to 90% by weight, more preferably 10 to 80% by weight, even more preferably 12 to 75% by weight, and most preferably 15 to 40% by weight.

[0128] When the aromatic vinyl block copolymer composition contains the block copolymers (C) and (D), the content ratio (C:D) thereof is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 5:95 to 90:10, more preferably 30:70 to 80:20, and even more preferably 50:50 to 70:30.

[0129] The aromatic vinyl block copolymer composition may contain a block copolymer other than the above-mentioned block copolymers (A) to (E). On the other hand, the aromatic vinyl block copolymer composition preferably consists of at least one block copolymer selected from the above-mentioned block copolymers (A) to (E), and more preferably at least one block copolymer selected from the block copolymers (A) to (D). It is more preferable that the aromatic vinyl block copolymer composition consists of only block copolymer (A), only block copolymers (A), (B), (C), and (D), only block copolymers (B), (C), and (D), only block copolymers (A), (B), and (C), only block copolymers (A), (B), and (D), only block copolymers (A), (C), and (D), only block copolymers (A) and (C), only block copolymers (A) and (D), only block copolymers (A) and (C), only block copolymers (A) and (D), only block copolymers (B) and (C), or only block copolymers (B) and (D). The aromatic vinyl block copolymer composition is particularly preferably composed of only block copolymer (A), or only block copolymers (A), (B), (C), and (D), or only block copolymers (B), (C), and (D).The aromatic vinyl block copolymer composition is most preferably composed of only block copolymers (A), (B), (C), and (D), or only block copolymers (B), (C), and (D).

[0130] (Method for Producing Aromatic Vinyl Block Copolymer) Aromatic vinyl block copolymers can be produced according to conventional methods. The most common production method is a method in which an aromatic vinyl monomer and a conjugated diene monomer are sequentially polymerized by anionic living polymerization to form a polymer block, and if necessary, a coupling agent is reacted to perform coupling. Alternatively, a method in which an aromatic vinyl monomer, a conjugated diene monomer, and then an aromatic vinyl monomer are sequentially polymerized in this order to form a polymer block may also be used. Alternatively, the copolymer can be produced by separately producing each polymer according to a conventional polymerization method, blending other polymer components, etc., as necessary, and then mixing them according to conventional methods such as kneading or solution mixing.

[0131] For example, the block copolymers (A2), (C) and (D) can be produced by the following production method (1).

[0132] (Production Method (1)) This production method comprises: a first polymerization step of polymerizing a monomer including an aromatic vinyl monomer in a solvent in the presence of a polymerization initiator to obtain a solution containing an aromatic vinyl polymer block chain; a second polymerization step of adding a monomer including a conjugated diene monomer to the solution containing the aromatic vinyl polymer block chain and polymerizing the monomer to obtain a solution containing a diblock chain; and a reaction step of adding a coupling agent to the solution containing the diblock chain to obtain a block copolymer ((A2), (C) or (D)).

[0133] In the above-described production method, first, a monomer containing an aromatic vinyl monomer as a main component is polymerized in a solvent using a polymerization initiator (first polymerization step). Examples of the polymerization initiator include organic alkali metal compounds, organic alkaline earth metal compounds, and organic lanthanoid series rare earth metal compounds, which are generally known to have anionic polymerization activity toward aromatic vinyl monomers and conjugated diene monomers. As the organic alkali metal compound, an organic lithium compound having one or more lithium atoms in the molecule is particularly suitable. Specific examples 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-dilithioethylcyclohexane; and organic trilithium compounds such as 1,3,5-trilithiobenzene. Among these, organic monolithium compounds are particularly suitable.

[0134] Examples of organic alkaline earth metal compounds used as polymerization initiators include n-butylmagnesium bromide, n-hexylmagnesium bromide, ethoxycalcium, calcium stearate, t-butoxystrontium, ethoxybarium, isopropoxybarium, ethylmercaptobarium, t-butoxybarium, phenoxybarium, diethylaminobarium, barium stearate, and ethylbarium. Specific examples of other polymerization initiators include composite catalysts consisting of a lanthanoid series rare earth metal compound containing neodymium, samarinium, gadolinium, or the like, an alkylaluminum, an alkylaluminum halide, and an alkylaluminum hydride, and metallocene catalysts containing titanium, vanadium, samarinium, gadolinium, or the like, which form a homogeneous system in an organic solvent and exhibit living polymerization properties. These polymerization initiators may be used alone or in combination of two or more.

[0135] The amount of the polymerization initiator used may be determined depending on the target molecular weight and is not particularly limited, 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.

[0136] The solvent used in the polymerization is not particularly limited as long as it is inert to the polymerization initiator, and for example, a chain hydrocarbon solvent, a cyclic hydrocarbon solvent, or a mixture thereof can be used. Examples of the chain hydrocarbon solvent include chain alkanes and alkenes having 4 to 6 carbon atoms, such as n-butane, isobutane, 1-butene, isobutylene, trans-2-butene, cis-2-butene, 1-pentene, trans-2-pentene, cis-2-pentene, n-pentane, isopentane, neo-pentane, and n-hexane. Specific examples of the cyclic hydrocarbon solvent include aromatic compounds such as benzene, toluene, and xylene; and alicyclic hydrocarbon compounds such as cyclopentane and cyclohexane. These solvents may be used alone or in combination.

[0137] The amount of the solvent used in the polymerization is not particularly limited, but is preferably set so that the concentration of the block copolymer in the finally obtained block copolymer solution is preferably in the range of 5 to 60% by weight, more preferably in the range of 15 to 55% by weight, and particularly preferably in the range of 25 to 50% by weight.

[0138] Furthermore, in order to control the structure of each polymer block, a Lewis base compound may be added to the reactor used for polymerization. Examples of the Lewis base compound include ethers such as tetrahydrofuran, diethyl ether, dioxane, ethylene glycol dimethyl ether, ethylene glycol dibutyl ether, diethylene glycol dimethyl ether, and diethylene glycol dibutyl ether; tertiary amines such as tetramethylethylenediamine, trimethylamine, triethylamine, pyridine, and quinuclidine; alkali metal alkoxides such as potassium t-amyl oxide and potassium t-butyl oxide; and phosphines such as triphenylphosphine. These Lewis base compounds may be used alone or in combination of two or more, and may be appropriately selected within a range that does not impair the object of the present disclosure.

[0139] The timing of adding the Lewis base compound during the polymerization reaction is not particularly limited and may be determined appropriately depending on the structure of the 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 added after some of the polymer blocks have been polymerized. For example, when a chain hydrocarbon solvent, a cyclic hydrocarbon solvent, or a mixed solvent thereof is used and tetramethylethylenediamine is used as the Lewis base compound, the amount of the Lewis base compound used is preferably 0.020 to 0.200 mol, more preferably 0.025 to 0.110 mol, and even more preferably 0.028 to 0.06 mol per mol of the polymerization initiator.

[0140] The polymerization reaction temperature is preferably 30 to 90°C, more preferably 35 to 85°C, and even more preferably 40 to 80°C. The time required for polymerization varies depending on the conditions, but is preferably 0.5 to 10 hours, more preferably 1 to 8 hours, and even more preferably 2 to 5 hours. The polymerization pressure may be within a range sufficient to maintain the monomer and solvent in a liquid phase within the above-mentioned polymerization temperature range, and the polymerization pressure is preferably 1 kPa or more, more preferably 10 kPa or more, and even more preferably 50 kPa or more.

[0141] Under the above conditions, a solution containing an aromatic vinyl polymer block chain can be obtained by polymerizing a monomer containing an aromatic vinyl monomer as a main component in a solvent using a polymerization initiator. The aromatic vinyl polymer block chain obtained by polymerization usually has an active terminal. The aromatic vinyl polymer block chain obtained has an active terminal. ａ２ , Ar ｃ or Ar ｄ ), the amount of the monomer used in this first polymerization step is determined based on the amount of the desired aromatic vinyl polymer block (Ar ａ２ , Ar ｃ or Ar ｄ ) may be determined depending on the weight average molecular weight of the copolymer.

[0142] Next, a monomer containing a conjugated diene monomer as a main component is added to the solution containing the aromatic vinyl polymer block chain obtained in the first polymerization step, and polymerization is carried out (second polymerization step). This allows a solution containing a diblock chain to be obtained. The diblock chain obtained by polymerization usually has an active terminal. The diblock chain obtained in the second polymerization step is also obtained by adding a monomer containing a conjugated diene monomer as a main component to the solution containing the aromatic vinyl polymer block chain obtained in the first polymerization step (Ar ａ２ , Ar ｃ or Ar ｄ ) in the polymer chain that will form a conjugated diene polymer block (D ａ２ , D ｃ or D ｄSince the polymer chains that will form the desired conjugated diene polymer block (D ａ２ , D ｃ or D ｄ The polymerization reaction temperature, polymerization time, and polymerization pressure may be controlled within the same ranges as in the first polymerization step.

[0143] Next, a coupling agent is added to the solution containing the diblock chains (reaction step), whereby the active ends of the diblock chains react with the coupling agent, resulting in two or more diblock chains being bonded together via the residue of the coupling agent, thereby forming a block copolymer ((A2), (C), or (D)).

[0144] The coupling agent is not particularly limited as long as it has two or more functional groups per molecule that can react with the active terminals of the diblock chains. However, a coupling agent having 2 to 8 functional groups per molecule that can react with the active terminals of the diblock chains is preferred, and a coupling agent having 2 to 4 functional groups per molecule that can react with the active terminals of the diblock chains is more preferred. Coupling agents with different numbers of functional groups may be used in combination. Furthermore, the coupling agent preferably contains a silicon atom, and halogenated silanes and alkoxysilanes are more preferred.

[0145] Examples of coupling agents (bifunctional coupling agents) having two functional groups per molecule that can react with the active terminals of the diblock chain include bifunctional halogenated silanes such as dichlorosilane, monomethyldichlorosilane, and dimethyldichlorosilane; bifunctional alkoxysilanes such as diphenyldimethoxysilane and diphenyldiethoxysilane; bifunctional halogenated alkanes such as dichloroethane, dibromoethane, methylene chloride, and dibromomethane; bifunctional tin halides such as dichlorotin, monomethyldichlorotin, dimethyldichlorotin, monoethyldichlorotin, diethyldichlorotin, monobutyldichlorotin, and dibutyldichlorotin; dibromobenzene, benzoic acid, CO, and 2-chloropropene. Among these, bifunctional halogenated silanes or bifunctional alkoxysilanes are particularly preferred. These bifunctional coupling agents may be used alone or in combination of two or more.

[0146] Examples of coupling agents having three functional groups per molecule that can react with the active terminals of the diblock chain (trifunctional coupling agents) include trifunctional halogenated alkanes such as trichloroethane and trichloropropane; trifunctional halogenated silanes such as methyltrichlorosilane and ethyltrichlorosilane; and trifunctional alkoxysilanes such as methyltrimethoxysilane, phenyltrimethoxysilane, and phenyltriethoxysilane. These trifunctional coupling agents may be used alone or in combination of two or more.

[0147] Examples of coupling agents having four functional groups per molecule that can react with the active terminals of the diblock chain (tetrafunctional coupling agents) include tetrafunctional halogenated alkanes such as carbon tetrachloride, carbon tetrabromide, and tetrachloroethane; tetrafunctional halogenated silanes such as tetrachlorosilane and tetrabromosilane; tetrafunctional alkoxysilanes such as tetramethoxysilane and tetraethoxysilane; and tetrafunctional tin halides such as tetrachlorotin and tetrabromotin. These tetrafunctional coupling agents may be used alone or in combination of two or more.

[0148] The number of branches of the block copolymer can be adjusted by adjusting the type, amount, and timing of addition of the coupling agent, the amount of the Lewis base compound, etc. Alternatively, the number of branches of the block copolymer can be adjusted by adjusting the coupling rate using a reaction terminator such as methanol. The number of branches of the block copolymer can also be adjusted by combining two or more coupling agents each having a different number of functional groups capable of reacting with the active end of the diblock chain. Furthermore, by these means, a portion of the diblock chain obtained in the second polymerization step can be left unreacted and ultimately recovered as a diblock copolymer (e.g., block copolymer (B)).

[0149] The amount of the coupling agent used is adjusted to an appropriate amount depending on the number of branches of the target block copolymer, and is preferably 0.05 to 1.0 molar equivalent, more preferably 0.10 to 0.85 molar equivalent, and even more preferably 0.20 to 0.70 molar equivalent, relative to the active terminal of the diblock chain.

[0150] The reaction temperature is preferably 10 to 100° C., more preferably 20 to 90° C., and even more preferably 30 to 80° C. The time required for the reaction varies depending on the conditions, but is usually within 48 hours, preferably 0.05 to 2 hours, and even more preferably 0.1 to 1.0 hour.

[0151] After the reaction step, the polymer component may be recovered from the solution containing the block copolymer (recovery step). 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 such as water, methanol, ethanol, propanol, hydrochloric acid, or citric acid may be added, and if necessary, an additive such as an antioxidant may be added, followed by direct drying or steam stripping of the solution to recover the polymer component. When the polymer component is recovered as a slurry by steam stripping or the like, the polymer component may be dehydrated using any dehydrator such as an extruder-type squeezer to obtain crumbs having a water content of a predetermined value or less, and the crumbs may then be dried using a dryer such as a band dryer, expansion extrusion dryer, or twin-screw extrusion dryer. The block copolymer obtained as described above may be processed into pellets or the like according to conventional methods before use. In this manner, a block copolymer ((A2), (C), or (D)) and optionally a diblock copolymer can be produced.

[0152] For example, the following production method (2) can be mentioned as a method for producing the block copolymers (A1) and (E).

[0153] (Production Method (2)) A preferred production method includes: a first polymerization step of polymerizing a monomer containing an aromatic vinyl monomer in a solvent in the presence of a polymerization initiator to obtain a solution containing an aromatic vinyl polymer block chain; a second polymerization step of adding a monomer containing a conjugated diene monomer to the solution containing the aromatic vinyl polymer block chain and polymerizing the monomer to obtain a solution containing a diblock chain; and a third polymerization step of adding a monomer containing an aromatic vinyl monomer to the solution containing the diblock chain and polymerizing the monomer to obtain a solution containing a block copolymer ((A1) or (E)).

[0154] In the above production method, first, a monomer containing an aromatic vinyl monomer as a main component is polymerized in a solvent using a polymerization initiator (first polymerization step). The solvent and its amount used, and the polymerization initiator and its amount used in the first polymerization step may be the same as those in the first polymerization step in production method (1). Also, as in the first polymerization step in production method (1), a Lewis base compound may be added, and the amount used may be the same. Also, the same polymerization reaction temperature, polymerization time, polymerization pressure, and stirring conditions for the polymerization reaction system as those in the first polymerization step in production method (1) may be used.

[0155] Under the above conditions, a solution containing an aromatic vinyl polymer block chain can be obtained by polymerizing a monomer containing an aromatic vinyl monomer as a main component in a solvent using a polymerization initiator. The aromatic vinyl polymer block chain obtained by polymerization usually has an active terminal. The aromatic vinyl polymer block chain obtained has an active terminal. ａ１ or Ar1 ｅ Therefore, the amount of the monomer used in this first polymerization step is ａ１ or Ar1 ｅ ) may be determined depending on the weight average molecular weight of the copolymer.

[0156] Next, a monomer containing a conjugated diene monomer as a main component is added to the solution containing the aromatic vinyl polymer block chain obtained in the first polymerization step, and polymerization is carried out (second polymerization step). This allows a solution containing a diblock chain to be obtained. The diblock chain obtained by polymerization usually has an active terminal. The diblock chain obtained in the second polymerization step also has an active terminal. ａ１ or Ar1 ｅ ) in the polymer chain that will form a conjugated diene polymer block (D ａ１ or D ｅ Since the polymer chains that form the conjugated diene polymer block (D) are further bonded, the amount of the monomer used in this second polymerization step is ａ１or D ｅ The polymerization reaction temperature, polymerization time, polymerization pressure, and stirring conditions of the polymerization reaction system may be controlled within the same ranges as in the first polymerization step.

[0157] Next, a monomer containing an aromatic vinyl monomer as a main component is added to the solution containing the diblock chain obtained in the second polymerization step, and polymerization is carried out (third polymerization step). This allows a solution containing the block copolymer (A1) or (E) to be obtained. The block copolymer (A1) or (E) obtained in the third polymerization step is the aromatic vinyl polymer block (Ar1) obtained in the second polymerization step. ａ１ or Ar1 ｅ ) and a conjugated diene polymer block (D ａ１ or D ｅ ) to the polymer chain that will form the aromatic vinyl polymer block (Ar2 ａ１ or Ar2 ｅ Since the polymer chains that form the aromatic vinyl polymer block (Ar2) are further bonded, the amount of the monomer used in this third polymerization step is ａ１ or Ar2 ｅ The polymerization reaction temperature, polymerization time, polymerization pressure, and stirring conditions of the polymerization reaction system may be controlled within the same ranges as in the first polymerization step.

[0158] Alternatively, in the third polymerization step, a monomer containing an aromatic vinyl monomer as a main component may be added, polymerization may be carried out, and then a polymerization terminator may be added in an amount less than 1 molar equivalent relative to the active terminals of the resulting triblock chain, followed by re-addition of a monomer containing an aromatic vinyl monomer as a main component and polymerization may be carried out. This method may also be used to obtain a solution containing block copolymers (A1) and (E).

[0159] After the third polymerization step, the polymer component may be recovered from the solution containing the block copolymer (A1) or (E) (recovery step). 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 such as water, methanol, ethanol, propanol, hydrochloric acid, or citric acid may be added, and if necessary, an additive such as an antioxidant may be added, followed by direct drying or steam stripping of the solution to recover the polymer component. When the polymer component is recovered as a slurry by steam stripping or the like, the polymer component may be dehydrated using an optional dehydrator such as an extruder-type squeezer to obtain crumbs having a water content of a predetermined value or less, and the crumbs may then be dried using an optional dryer such as a band dryer, expansion extrusion dryer, or twin-screw extrusion dryer. The block copolymer obtained as described above may be processed into pellets or the like according to conventional methods before use. In this manner, the block copolymers (A1) and (E) can be produced.

[0160] [Elastomer Composition] The elastomer composition of the present disclosure may consist solely of a polyolefin elastomer, or may consist solely of a polyolefin elastomer and an aromatic vinyl block copolymer, or may contain other components. The total content of the polyolefin elastomer and the aromatic vinyl block copolymer in the elastomer composition of the present disclosure is preferably 90% by weight or more, more preferably 95% by weight or more, and even more preferably 99% by weight or more.

[0161] Other components include fatty acid amides, waxes, antioxidants, tackifying resins, softeners, antibacterial agents, light stabilizers, ultraviolet absorbers, dyes, lubricants, pigments, and the like.

[0162] The fatty acid amide may be an aliphatic monoamide or an aliphatic bisamide. The aliphatic monoamide is not particularly limited as long as it is a compound in which a hydrocarbon group and one amide group (-NHCO) are bonded together, but a monoamide of a higher saturated fatty acid having 12 or more carbon atoms (i.e., a compound in which a chain alkyl group having 12 or more carbon atoms and one amide group (-NHCO) are bonded together) is preferably used.

[0163] Specific examples of fatty acid monoamides include saturated fatty acid monoamides such as lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, behenic acid amide, and hydroxystearic acid amide; and unsaturated fatty acid monoamides such as oleic acid amide and erucic acid amide.

[0164] The content of the fatty acid amide is preferably 0.2 to 10 parts by weight, more preferably 0.3 to 8 parts by weight, and even more preferably 0.5 to 6 parts by weight, based on 100 parts by weight of the total of the polyolefin elastomer and the aromatic vinyl block copolymer.

[0165] Specific examples of waxes include polyethylene wax and waxes containing linear and branched hydrocarbons. The wax may be natural or synthetic, but is preferably natural wax, and more preferably petroleum wax. A blended wax containing petroleum wax as the main component and some other natural or synthetic wax may also be used. Furthermore, in order to improve the functionality and processability of these waxes, a small amount of resin or the like may also be blended with the wax.

[0166] Polyethylene wax is a wax whose main constituent unit is an ethylene monomer unit. The polyethylene wax is not particularly limited, but one having a viscosity of 20 to 6,000 mPa·s at 140°C is preferably used. Polyethylene wax is generally produced by the polymerization of ethylene or the decomposition of polyethylene, and either type of polyethylene wax may be used. Commercially available polyethylene waxes are also available, and specific examples include "A-C Polyethylene" (manufactured by Honeywell), "Mitsui Hiwax" (manufactured by Mitsui Chemicals, Inc.), "Sunwax" (manufactured by Sanyo Chemical Industries, Ltd.), and "Epolene" (manufactured by Eastman Chemical Company).

[0167] The linear hydrocarbons constituting the wax containing linear hydrocarbons and branched hydrocarbons are preferably linear aliphatic saturated hydrocarbons. The linear hydrocarbons are sometimes called normal paraffins. The branched hydrocarbons are preferably branched aliphatic saturated hydrocarbons. The branched hydrocarbons are sometimes called isoparaffins. As the linear hydrocarbons and branched hydrocarbons, the linear hydrocarbons and branched hydrocarbons contained in petroleum wax are preferred.

[0168] The wax containing linear and branched hydrocarbons may contain cyclic hydrocarbons in addition to the linear and branched hydrocarbons, and the total amount of linear and branched hydrocarbons in the wax is preferably 50% by mass or more, more preferably 70% by mass or more, even more preferably 80% by mass or more, and most preferably 90% by mass or more.

[0169] The weight ratio (n-isomer / iso-isomer) of the linear hydrocarbons (n-isomer) to the branched hydrocarbons (iso-isomer) in the wax containing linear hydrocarbons and branched hydrocarbons is 30 / 70 to 99 / 1, preferably 50 / 50 to 97 / 3, more preferably 70 / 30 to 95 / 5, and most preferably 75 / 25 to 90 / 10.

[0170] The melting point of the wax is less than 80° C., preferably 76° C. or less, more preferably 73° C. or less, and preferably 30° C. or more, more preferably 40° C. or more, and even more preferably 45° C. or more. The melting point of the wax can be measured using a differential scanning calorimeter or the like. When the melting point of the wax is within the above range, the handleability is excellent and the ozone crack resistance and blocking resistance of the resulting elastomer sheet can be improved.

[0171] The content of the wax is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 3.5 parts by weight, and even more preferably 0.5 to 2 parts by weight, based on 100 parts by weight of the total of the polyolefin elastomer and the aromatic vinyl block copolymer.

[0172] The antioxidant is not particularly limited, and examples thereof include hindered phenol compounds such as pentaerythritol tetrakis[3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate], octadecyl-3-(3,5-di-t-butyl-4-hydroxyphenyl)propionate, 2,6-di-t-butyl-p-cresol, di-t-butyl-4-methylphenol, 4-[[4,6-bis(octylthio)-1,3,5-triazin-2-yl]amino]-2,6-di-tert-butylphenol, 2,4-bis[(dodecylthio)methyl]-6-methylphenol, and 4,6-bis(octylmethyl)-o-cresol; thiodicarboxylate esters such as dilaurylthiopropionate; tris(nonylphenyl)phosphite, butylidene bis(octylmethyl)propionate, and the like. Phosphites such as 3-methyl-6-t-butylphenyl-di-tridecyl phosphite can be used.

[0173] The content of the antioxidant is preferably 10 parts by weight or less, more preferably 0.05 to 5 parts by weight, based on 100 parts by weight of the total of the polyolefin elastomer and the aromatic vinyl block copolymer.

[0174] By incorporating a pigment, the elastomer sheet can be toned to a desired color tone. Common pigments can be incorporated as needed, and the type is not particularly limited. To reduce the gloss of the elastomer sheet, it is preferable to incorporate a filler such as titanium oxide or calcium carbonate, with titanium oxide being most preferred. While there is no particular limitation on whether the filler is surface-treated, it is preferable to use a surface-treated filler to improve its dispersibility in the resin, with alumina treatment, fatty acid treatment, and alkylsilane treatment being more preferred, and alumina treatment being most preferred. To improve its dispersibility in the resin, the filler is preferably incorporated together with a fatty acid metal salt. As the fatty acid metal salt, calcium stearate or zinc stearate is more preferred, and a combination of calcium stearate and zinc stearate is most preferred. The amount of filler is not particularly limited, but is preferably 0.1 to 20 parts by weight, more preferably 0.5 to 10 parts by weight, even more preferably 0.8 to 5 parts by weight, and most preferably 1 to 3 parts by weight, per 100 parts by weight of the polyolefin elastomer and aromatic vinyl block copolymer combined. The amount of fatty acid metal salt to be added is not particularly limited, but is usually 0.01 to 3 times, preferably 0.1 to 2 times, and most preferably 0.2 to 1 time the amount of filler to be added.

[0175] The method for mixing the components to obtain the elastomer composition of the present disclosure is not particularly limited. Examples include a method in which the components are dissolved in a solvent and mixed uniformly, and then the solvent is removed by heating, or a method in which the components are melt-mixed using a screw extruder, kneader, or the like. Among these, melt-mixing is preferred from the viewpoint of more efficient mixing. The temperature at which the melt-mixing is performed is not particularly limited, but is typically in the range of 100 to 250°C.

[0176] When the components are melt-mixed, in order to mix them more uniformly, masterbatch pellets may be prepared in advance by kneading all or part of one or more of the components in a single-screw extruder, twin-screw extruder, Banbury mixer, kneader, etc. Among the above, the use of a twin-screw extruder or a Banbury mixer is particularly preferred from the viewpoints of kneading ability, cleanability, and cost.

[0177] <Elastomer Sheet> The elastomer sheet of the present disclosure is used to form the composite sheet described above and is formed using the elastomer composition of the present disclosure. The elastomer sheet of the present disclosure is preferably an extrusion molded product of the elastomer composition of the present disclosure. The elastomer sheet of the present disclosure is a composite sheet that is suitably used for producing an elastic member and can provide a composite sheet suitable for roll packaging.

[0178] The thickness of the elastomer sheet of the present disclosure is not particularly limited, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 0.005 to 1 mm, more preferably 0.01 to 0.5 mm, even more preferably 0.015 to 0.2 mm, and most preferably 0.02 to 0.06 mm.

[0179] The elastomer sheet of the present disclosure may be perforated with a plurality of holes to provide breathability. In this case, increasing the aperture ratio of the film of the elastomer sheet can increase the moisture permeability of the resulting elastic member.

[0180] In particular, elastic members used in sanitary products such as disposable diapers and sanitary napkins are desired to have high moisture permeability to prevent stuffiness. One method for achieving high moisture permeability is to drill multiple holes in an elastomer sheet. In this case, increasing the film's aperture ratio improves moisture permeability, but increasing the aperture ratio also reduces the film's effective cross-sectional area, placing excessive stress on the film, which can lead to the film tearing through the holes during wear or the elastic member failing to return to its original length due to stress relaxation of the material itself (i.e., stretching). This stretching can lead to a poor fit to the wearer's body and to the creation of gaps between the body and the diaper, which can lead to waste leakage. In contrast, the elastomer sheet of the present disclosure formed using the elastomer composition of the present disclosure also has excellent stress relaxation properties, so such problems can be effectively prevented even when the film's aperture ratio is increased.

[0181] The method for molding the elastomer composition of the present disclosure into an elastomer sheet is not particularly limited, and any conventionally known molding method can be applied. However, from the viewpoint of obtaining a smooth elastomer sheet with good productivity, melt extrusion molding is preferred, and among these, melt extrusion molding using a T-die is particularly preferred.

[0182] <Composite Sheet> The composite sheet of the present disclosure is formed by laminating and adhering the elastomer sheet of the present disclosure to a substrate in a state of elongation of 5 to 50%. The composite sheet of the present disclosure also has a tensile elongation of 20% or less in the elongation direction when adhered, when a tensile test is performed under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C.

[0183] The composite sheet of the present disclosure is formed by bonding the elastomer sheet of the present disclosure to a substrate in a state in which the elastomer sheet is elongated at a relatively low elongation rate of 5 to 50%. By maintaining the elongation rate within this range during bonding, the composite sheet undergoes little elongation when wound into a roll, and a composite sheet with excellent storage stability for a roll package can be provided with high production stability.

[0184] The elongation rate during adhesion is not particularly limited as long as it is 5 to 50%, but from the viewpoint of further enhancing the effects of the present disclosure, it is preferably 8 to 35%, and more preferably 12 to 25%.

[0185] The composite sheet of the present disclosure has a tensile elongation of 20% or less in the elongation direction during adhesion when subjected to a tensile test under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23° C. The composite sheet of the present disclosure has small elongation when wound into a roll, and excellent storage stability for the roll package, yet can provide an elastic member with excellent stretchability (particularly flexibility, recovery, and resistance to stretching to completion).

[0186] The substrate used is a substrate that exhibits substantially no stretchability. Specifically, the tensile elongation of the substrate measured under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 25°C is preferably 10% or less.

[0187] As the substrate, a nonwoven fabric is preferred. The raw material fibers of the nonwoven fabric are not particularly limited, but include synthetic fibers such as polyolefins, polyesters, and polyamides; regenerated fibers such as rayon and cupra; natural fibers such as cotton; and mixed or composite fibers using two or more of these. Among these, polyolefins are most preferred. The nonwoven fabric may be manufactured by a known method, such as a spunlace method, a spunbond method, a thermal bond method, a meltblown method, a needle punch method, an air-through method, or a point bond method.

[0188] The basis weight of the substrate is not particularly limited, but is preferably 5 to 30 g / m ２ It is preferable that the substrate is a laminate obtained by laminating two or more substrates.

[0189] The composite sheet of the present disclosure is also preferably a laminate comprising a first substrate and a second substrate, the first substrate, an elastomer sheet, and the second substrate laminated in this order. In this case, the first substrate and the second substrate may be the same substrate or different substrates.

[0190] The composite sheet of the present disclosure is preferably produced by a production method in which the elastomer composition of the present disclosure is melt-molded into a sheet, and immediately thereafter, the sheet is stretched at a relatively low elongation rate of 5 to 50% in the same process, without being rolled up and stored, and the stretched elastomer sheet of the present disclosure is bonded to a substrate.

[0191] For example, if the elastomer composition of the present disclosure is melt-molded to form a sheet-like intermediate and then immediately stretched at a relatively low elongation rate of 5 to 50%, the sheet-like intermediate is stretched to produce an elastomer sheet that is even thinner than when it was formed. Furthermore, in this case, the elastomer sheet is sufficiently stretched to a length substantially equal to that of the substrate sheet, resulting in a non-stretchable composite sheet. Here, if the elongation rate is 5% or less, the elastomer sheet cannot be sufficiently thinned. Furthermore, the composite sheet is prone to sagging during transport, which reduces the manufacturing stability of the composite sheet. On the other hand, if the elongation rate exceeds 50%, the resulting composite sheet will elongate significantly when wound into a roll, making it unsuitable for roll packaging.

[0192] One method for producing a composite sheet involves producing an elastomer sheet in advance, preparing a package containing the elastomer sheet alone, and then adhering the elastomer sheet to a substrate while pulling it out of the package. However, this method can easily cause problems, such as adhesion between the elastomer sheets inside the package, making it difficult to pull out the elastomer sheet or to stretch the elastomer sheet to make it thinner.

[0193] In the following, an embodiment of the method for producing a composite sheet according to the present disclosure will be exemplified, in which a first substrate and a second substrate are used. Specifically, an elastomer sheet according to the present disclosure is formed using the elastomer composition according to the present disclosure and two sets of nonwoven fabrics, and the elastomer sheet is then stretched, and the nonwoven fabrics, the elastomer sheet stretched by 5 to 50%, and the nonwoven fabrics are then laminated and bonded in this order.

[0194] Fig. 1 is a schematic diagram of a manufacturing apparatus for manufacturing a composite sheet according to an embodiment of the present disclosure. As shown in Fig. 1, the manufacturing apparatus for a composite sheet includes a melt-extrusion mechanism 10, a cooling roll 11, a stretching mechanism 20, a lamination mechanism 30, an ultrasonic bonding machine 80, and a control device (not shown). The control device controls the melt-extrusion mechanism 10, the cooling roll 11, the stretching mechanism 20, and the lamination mechanism 30 to operate in coordination with each other.

[0195] The melt extrusion mechanism 10 extrudes the heated and melted elastomer composition in the form of a film to form a film-like melt 40. The melt extrusion mechanism 10 is, for example, a melt extrusion molding mechanism using a T-die, and may be a twin-screw extruder equipped with a T-die.

[0196] As shown in Fig. 1, a cooling roll 11 is disposed below the melt extrusion mechanism 10, and the melt 40 discharged from the melt extrusion mechanism 10 is stretched before reaching the cooling roll 11. That is, the cooling roll 11 rotates at a peripheral speed higher than the feed speed of the elastomer composition when it is discharged from the discharge port of the melt extrusion mechanism 10, thereby stretching the melt 40 until the thickness of the film-like melt 40 reaches a predetermined value. In the present disclosure, from the viewpoint of increasing the width of the melt 40 discharged from the melt extrusion mechanism 10 and thereby increasing the width of the film that is finally obtained, it is preferable that the distance between the discharge port of the melt extrusion mechanism 10 and the cooling roll 11 be as short as possible, and preferably less than 50 mm. In addition, from the viewpoint of bringing the molten material 40 discharged from the melt extrusion mechanism 10 into contact with the cooling roll 11 as early as possible, it is also preferable to provide a blowing mechanism for blowing air onto the molten material 40 (a mechanism for blowing air flowing from left to right in the drawing toward the molten material 40 discharged from the discharge port of the melt extrusion mechanism 10).

[0197] The cooling roll 11 has a flow path (not shown) formed therein through which a refrigerant flows, and while the molten material 40 advances in the feed direction while in contact with the outer peripheral surface of the cooling roll 11, the molten material 40 is cooled and solidified to a temperature range in which the elastomer composition constituting the molten material 40 solidifies. As a result, the molten material 40 becomes an elastomer sheet 40a, and is drawn out from the cooling roll 11.

[0198] The elastomer sheet 40a is sent to the stretching mechanism 20 via the guide rolls 12. The stretching mechanism 20 includes a pull-out roll 13, a pull-out nip roll 14 facing the pull-out roll 13, a first stretching roll 15, a stretching nip roll 16 facing the pull-out roll 13, and a second stretching roll 17. The stretching mechanism 20 stretches the elastomer sheet 40a by 5 to 50%.

[0199] The elastomer sheet 40a is stretched in the section from between the pull-out roll 13 and the pull-out nip roll 14, through between the first stretching roll 15 and the stretching nip roll 16, to the second stretching roll 17. That is, the pull-out roll 13, the first stretching roll 15, and the second stretching roll 17 are rotated in this order at successively faster peripheral speeds, whereby the elastomer sheet 40a is stretched in two stages at a predetermined stretch ratio. Specifically, the elastomer sheet 40a is stretched at a first magnification between the pull-out roll 13 and the first stretching roll 15 due to the difference in peripheral speed between them (due to the action of the first stretching roll 15, which has a faster peripheral speed), and then the elastomer sheet 40a stretched at the first magnification is stretched at a second magnification between the first stretching roll 15 and the second stretching roll 17 due to the difference in peripheral speed between them (due to the action of the second stretching roll 17, which has a faster peripheral speed).

[0200] The lamination mechanism 30 supplies a first nonwoven fabric 50 as a first base sheet to the second stretching roll 17 via a guide roll 18, and also supplies a second nonwoven fabric 60 as a second base sheet to the second stretching roll 17 via a guide roll 19. The elastomer sheet 40a stretched by 5 to 50% along the second stretching roll 17 is then sandwiched between the first nonwoven fabric 50 and the second nonwoven fabric 60, and the elastomer sheet 40a stretched by 5 to 50% is laminated between the first nonwoven fabric 50 and the second nonwoven fabric 60.

[0201] A laminate formed by laminating a first nonwoven fabric (50), an elastomer sheet (40a) stretched by 5 to 50%, and a second nonwoven fabric (60) is subjected to ultrasonic bonding using an ultrasonic bonding machine (80), thereby bonding the elastomer sheet to the first nonwoven fabric (50) and the second nonwoven fabric (60) in a state of being stretched by 5 to 50%.

[0202] The ultrasonic bonding machine 80 typically comprises a resonator (horn) and a receiving jig (anvil roll). The receiving jig (anvil roll) has multiple protrusions on its outer circumferential surface, which allows the ultrasonic energy to be selectively concentrated at specific locations, enabling point bonding (local bonding). The second tensioning roll 17 may be an anvil roll having multiple protrusions on its outer circumferential surface, or the anvil roll may be located downstream of the second tensioning roll 17. The point bonding pattern is not particularly limited, and any known pattern may be employed. When the composite sheet 70 is a porous body, patterned openings can be formed by applying ultrasonic waves from the ultrasonic bonding machine 80 during ultrasonic bonding.

[0203] As described above, by using the manufacturing apparatus shown in FIG. 1 , a composite sheet can be manufactured by laminating a first substrate, an elastomer sheet stretched by 5 to 50%, and a second substrate in this order. The manufacturing method of the composite sheet of the present disclosure is not limited to the above method. For example, by not using the second substrate, a composite sheet can be manufactured by laminating an elastomer sheet stretched by 5 to 50% on a substrate.

[0204] The resulting composite sheet 70 is packaged by a packaging machine (not shown). Any conventionally known packaging machine can be used. A packaging machine that rolls up the composite sheet 70 and packages it is preferred, as this provides excellent stability and productivity in the packaging operation, excellent handling of the package, and allows the package to be stored in a small space.

[0205] The elastic member of the present disclosure is obtained by stretching the composite sheet of the present disclosure while mechanically processing the substrate constituting the composite sheet of the present disclosure. The elastic member of the present disclosure has a tensile elongation of 100% or more in the elongation direction when bonded, measured under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C.

[0206] In the composite sheet of the present disclosure, the substantially non-stretchable substrate resists tensile deformation of the composite sheet, resulting in the composite sheet having the aforementioned low tensile elongation and being less likely to stretch. In contrast, by stretching the composite sheet while mechanically processing the substrate, the tensile resistance of the substrate is weakened, allowing the elastomer sheet to exhibit its stretchability. As a result, the elastic member of the present disclosure exhibits the aforementioned large tensile elongation, making it stretchable and usable as an elastic member.

[0207] The tensile elongation of the elastic member of the present disclosure, measured in the elongation direction during bonding under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C, is 100% or more. The elastic member of the present disclosure thus has a large tensile elongation and excellent elasticity. The tensile elongation of the elastic member of the present disclosure is not particularly limited as long as it is 100% or more, but is preferably 110 to 500%, and more preferably 130 to 300%.

[0208] The stretching ratio when stretching the composite sheet while mechanically processing the substrate is preferably 100 to 500%, more preferably 110 to 300%, and the stretching direction is preferably the same as the stretching direction of the elastomer sheet when bonding the elastomer sheet to the substrate.

[0209] The thickness of the elastomer sheet in the elastic member of the present disclosure is preferably 10 to 100 μm, more preferably 20 to 50 μm.

[0210] The method for stretching a composite sheet while machining the substrate is not particularly limited. For example, a method using a stretching device equipped with a pair of grooved rolls can be used. Here, a pair of grooved rolls refers to rolls having axially extending, interlocking grooves on the circumferential surfaces of both rolls. When the grooved rolls are rotating, the composite sheet is fed into the interlocking portion and is thereby stretched in the circumferential direction of the grooved rolls (i.e., the MD direction). Below, a case where a stretching device equipped with a pair of grooved rolls is used is exemplified as a method for stretching a composite sheet while machining the substrate.

[0211] The toothed roll rotates by meshing with the other by transmitting a driving force from a driving means to one of the rotation shafts. A general gear specified in JIS B1701 may be attached to each shaft of the toothed roll as a driving gear in addition to the teeth. In this way, the teeth of the toothed roll do not mesh with each other, but rather the gears mesh with each other, thereby transmitting the driving force to the toothed roll and rotating the toothed roll. In this case, the teeth of the toothed roll do not need to come into contact with each other.

[0212] In the stretching device, a pair of grooved rolls are rotated, and a composite sheet is supplied to the meshing portion between the grooved rolls, and the composite sheet is stretched between the grooved rolls.

[0213] The above-described method allows the composite sheet to be stretched while mechanically processing the substrate in the composite sheet. During this process, the substrate is sufficiently stretched, thereby weakening the tensile resistance of the substrate and allowing the stretchability of the elastomeric sheet to be exerted, resulting in efficient production of a highly stretchable elastic member. For example, when a nonwoven fabric is used as the substrate, the above-described method destroys at least a portion of the microstructure of the nonwoven fabric, thereby weakening the tensile resistance of the substrate.

[0214] The elastic member of the present disclosure has excellent elasticity (particularly flexibility, recovery, and resistance to full stretching), and can therefore be suitably used as an elastic member for sanitary products such as disposable diapers and sanitary products.

[0215] The present invention will be described in more detail below with reference to examples and comparative examples, but the present invention is not limited to these examples. The "parts" are by weight unless otherwise specified. The test methods used in these examples and comparative examples are as follows.

[0216] [Weight-average molecular weight of each block copolymer] The weight-average molecular weight was determined as a polystyrene-equivalent molecular weight by high-performance liquid chromatography using tetrahydrofuran as a carrier at a flow rate of 0.35 ml / min. The analyzer was a Tosoh HLC8320, the column consisted of three connected Shodex 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 Tosoh.

[0217] [Weight Ratio of Each Block Copolymer in the Block Copolymer Composition] The weight ratio was determined from the area ratio of the peak corresponding to each block copolymer in the chart obtained by the above high performance liquid chromatography.

[0218] [Weight-Average Molecular Weight of Styrene Polymer Block of Each Block Copolymer] According to the method described in Rubber Chem. Technol., 45, 1295 (1972), the block copolymer was reacted with ozone and reduced with lithium aluminum hydride to decompose the isoprene polymer block of the block copolymer. Specifically, the following procedure was performed. 300 mg of sample was dissolved in a reaction vessel containing 100 ml of dichloromethane treated with molecular sieves. The reaction vessel was then 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 nitrogen-purged reaction vessel. 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 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 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.

[0219] [Weight-Average Molecular Weight of Isoprene Polymer Block of Each Block Copolymer] The weight-average molecular weight of the corresponding styrene polymer block was subtracted from the weight-average molecular weight of the block copolymer determined as described above, and the weight-average molecular weight of the isoprene polymer block was determined based on the calculated value.

[0220] [Vinyl bond content of isoprene polymer block of each block copolymer] Deuterated chloroform was used as the solvent. １ The vinyl bond content was determined based on H-NMR measurement.

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[0222] [Melt Index] The melt index was measured in accordance with ASTM D-1238 (G condition, 200°C, 5 kg).

[0223] [Moldability of Elastomer Composition] Elastomer sheets (unstretched sheets) with an average thickness of 0.04 mm were continuously obtained using the same extrusion molding method as in each Example and Comparative Example. The film width of the obtained elastomer sheets was measured. Specifically, the elastomer sheet was cut into a length of 900 mm in the MD direction, and the width (TD width) was measured at a total of 10 points at 100 mm intervals. The standard deviation of the width was calculated from the obtained results. A smaller standard deviation of the width indicates smaller pulsation (so-called draw resonance) during melt molding, which means that film molding can be performed stably for a long period of time. Therefore, the smaller the standard deviation of the width, the better the moldability of the elastomer composition can be determined. A standard deviation of the width of less than 2.0 mm was determined to be good moldability.

[0224] [Roll Winding Property of Composite Sheet] A test piece was prepared by punching out the composite sheet to a length of 100 mm and a width of 50 mm, with the MD (machine direction) as the length direction. The test piece was attached to a tensile tester (Tensilon universal testing machine, RTI-1225, manufactured by ORIENTEC) so that the length direction was the tensile direction, and a tensile test was performed at a temperature of 23°C. The tensile elongation of the composite sheet was then calculated from the amount of movement when a load of 2.5 N was reached. The smaller the tensile elongation value, the more suitable the composite sheet is for roll packaging. A tensile elongation value of 20% or less was determined to have good roll winding property. Detailed test conditions and calculation formulas are shown below.

[0225] (Tensile test conditions) Distance between chucks: 50 mm Tensile speed: 300 mm / min

[0226] (Formula for calculating elongation of composite sheet) Elongation of composite sheet (%) = (amount of movement when load reaches 2.5 N) / (distance between chucks) × 100

[0227] [Tensile elongation of elastic member] A test piece was prepared by punching out an elastic member with a length of 100 mm and a width of 50 mm, with the MD (machine direction) as the length direction. The test piece was attached to a tensile tester (Tensilon universal testing machine, RTI-1225, manufactured by ORIENTEC) so that the length direction was the tensile direction, and a tensile test was performed at a temperature of 23 ° C. Then, the tensile elongation of the elastic member was calculated from the amount of movement when a load of 10 N was reached. When the tensile elongation was 100% or more, it was determined that the elastic member could be used. Detailed test conditions and calculation formulas are shown below.

[0228] (Tensile test conditions) Distance between chucks: 50 mm Tensile speed: 300 mm / min

[0229] (Formula for calculating elongation of composite sheet) Elongation of composite sheet (%) = (amount of movement when load reaches 2.5 N) / (distance between chucks) × 100

[0230] [Stress and permanent strain at 100% elongation of elastic member] A test piece was prepared by punching out an elastic member to a length of 100 mm and a width of 50 mm, with the MD (machine direction) as the length direction. The test piece was attached to a tensile tester (Tensilon universal testing machine, RTI-1225, manufactured by ORIENTEC) so that the length direction was the tensile direction, and a tensile test was performed at a temperature of 23 ° C. Then, the stress and permanent strain at 100% elongation were measured. If the stress at 100% elongation is too large, it can be determined that the elastic member has poor flexibility and is difficult to stretch. If the stress at 100% elongation is too small, it can be determined that the elastic member has poor stretchability. On the other hand, if the stress at 100% elongation is appropriate, it can be determined that the elastic member has excellent flexibility and excellent stretchability. Furthermore, the smaller the permanent strain at 100% elongation, the better the elastic member's recovery and stretchability. When the stress at 100% elongation was 0.5 MPa or more and 1.9 MPa or less, the stress characteristics were judged to be good. Furthermore, when the permanent set at 100% elongation was less than 20%, the recovery property was judged to be excellent. Detailed test conditions are shown below.

[0231] - Test specimen shape: Width 25 mm x Length 100 mm (length direction is MD direction) - Test temperature: 23°C - Grip distance: 50 mm - Test speed: 300 mm / min - Tensile cycle: Stroke strain 0% → 100% (30-second hold) → 0% was considered one cycle, and this was repeated twice. - Data processing: The load at 100% stroke strain (after 30-second hold) in the second cycle was read, and this was divided by the cross-sectional area of ​​the elastomer sheet to calculate the stress at 100% elongation (unit: MPa). - Cross-sectional area of ​​the film: The width was 25 mm, and the thickness of the elastomer sheet portion before the test was read to the nearest 0.001 mm using an optical microscope, and the calculation was made as follows: Cross-sectional area (mm^2) = Width (mm) × Thickness (mm). Permanent set: In the second cycle, the stroke strain was changed from 100% to 0%, and the stroke strain at the point where the load reached 0 N was recorded as the permanent set (unit: %).

[0232] [Stress Relaxation Properties of Elastic Members] Elastic members were cut into strips measuring 100 mm in length and 25 mm in width, with the MD (machine direction) as the length direction, to prepare test pieces. A stress relaxation test was then performed. Specifically, the initial length (grip distance) of the test piece was 50 mm, both ends of the test piece were held, and the test piece was placed in an oven at 38°C and held for 6 hours in a state where it was stretched 100% in the MD direction. After 6 hours, the test piece was returned to its original state, and the elongation of the test piece was calculated according to the following formula: Elongation [%] = {(Length after 6 hours) - (Initial length, 50 mm)} ÷ (Initial length, 50 mm) × 100

[0233] If the elongation rate is less than 30%, the elastic member can be judged to have excellent resistance to stretching and excellent elasticity. Note that, if a crack propagated from the hole in the elastomer sheet during the stress relaxation test and the film broke, this is indicated as "Break" in Table 4.

[0234] [Thickness of elastomer sheet in elastic member] The elastic member was cut with scissors to a length of 100 mm in the MD (machine direction) and a width of 25 mm in the CD, and the cross section in the longitudinal direction was observed with an optical microscope to measure the thickness of the elastomer sheet portion to the nearest 1 μm. The smaller the thickness of the elastomer sheet in the elastic member, the easier it is to thin the elastic member. An elastomer sheet thickness of less than 35 mm was determined to have excellent thinning properties.

[0235] [Production Example 1] (Production of Styrene-Isoprene Block Copolymer Composition (1)) A pressure-resistant reactor was charged with 23.2 kg of cyclohexane, 1.9 mmol of N,N,N',N'-tetramethylethylenediamine (hereinafter referred to as "TMEDA"), and 0.70 kg of styrene, and the stirring Reynolds number was 160,000 and the stirring power required by the stirring blade was 3 kW / m. ３While stirring at 40°C, 64.4 mmol of n-butyllithium was added, and polymerization was continued for 1 hour while the temperature was raised to 50°C and stirring was continued at the same rotation speed. The polymerization conversion of styrene was 100%. Subsequently, while controlling the temperature to maintain 50 to 60°C, stirring was continued at the same rotation speed, and 6.34 kg of isoprene was continuously added to the reactor over 1 hour. After the addition of isoprene was completed, polymerization was continued for another 1 hour by continuing stirring at the same rotation speed. The polymerization conversion of isoprene was 100%. Next, while continuing to control the temperature to maintain 50 to 60°C and stirring at the same rotation speed, 0.70 kg of styrene was continuously added over 1 hour. After the addition of styrene was completed, polymerization was continued for another 1 hour by continuing stirring at the same rotation speed, and triblock chains having active ends were formed. The polymerization conversion of styrene was 100%. Next, 129 mmol of methanol was added as a polymerization terminator and mixed. A portion of the resulting reaction mixture was taken out and the block copolymer was evaluated according to the above-mentioned measurement method. The results are shown in Table 2.

[0236] To 100 parts of the reaction liquid obtained as described above (containing 30 parts of the polymer component), 0.3 parts of 2,6-di-tert-butyl-p-cresol was added as an antioxidant 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, thereby obtaining a precipitate. This precipitate was pulverized and dried with hot air at 85°C, thereby recovering a styrene-isoprene block copolymer composition.

[0237] [Production Example 2] (Production of Styrene-Isoprene Block Copolymer Composition (2)) A pressure-resistant reactor was charged with 23.2 kg of cyclohexane, 3.6 mmol of TMEDA, and 1.55 kg of styrene. The stirring Reynolds number was 160,000, and the stirring power required by the stirring blades was 3 kW / m. ３While stirring at 40°C, 121.2 mmol of n-butyllithium was added, and polymerization was continued for 1 hour while the temperature was raised to 50°C and stirring was continued at the same rotation speed. The polymerization conversion of styrene was 100%. Subsequently, stirring was continued at the same rotation speed while controlling the temperature to maintain 50-60°C, and 6.18 kg of isoprene was continuously added to the reactor over 1 hour. After the addition of isoprene was completed, polymerization was continued for another 1 hour by continuing stirring at the same rotation speed. The polymerization conversion of isoprene was 100%. Next, 5.2 mmol of tetramethoxysilane (a tetrafunctional coupling agent) and 42.4 mmol of dimethyldichlorosilane (a bifunctional coupling agent) were added. Next, 242 mmol of methanol was added as a polymerization terminator and mixed. A portion of the resulting reaction solution was removed, and the block copolymer was evaluated according to the measurement method described above. The results are shown in Table 2.

[0238] To 100 parts of the reaction liquid obtained as described above (containing 30 parts of the polymer component), 0.3 parts of 2,6-di-tert-butyl-p-cresol was added as an antioxidant 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, thereby obtaining a precipitate. This precipitate was pulverized and dried with hot air at 85°C, thereby recovering a styrene-isoprene block copolymer composition.

[0239] [Production Example 3] (Production of Styrene-Isoprene Block Copolymer Composition (3)) A reaction solution and a styrene-isoprene block copolymer composition were obtained in the same manner as in Production Example 2, except that the amounts of each raw material used were changed as shown in Table 1 and dimethyldichlorosilane was not used. The evaluation results are shown in Table 2.

[0240] [Production Example 4] (Production of Styrene-Isoprene Block Copolymer Composition (4)) A reaction solution and a styrene-isoprene block copolymer composition were obtained in the same manner as in Production Example 2, except that the amounts of each raw material used were changed as shown in Table 1. The evaluation results are shown in Table 2.

[0241] [Production Example 5] (Production of Styrene-Isoprene Block Copolymer Composition (5)) A pressure-resistant reactor was charged with 23.2 kg of cyclohexane, 3.6 mmol of TMEDA, and 0.73 kg of styrene, and the stirring Reynolds number was 160,000 and the stirring power required by the stirring blade was 3 kW / m. ３ While stirring at 40°C, 71.8 mmol of n-butyllithium was added, and polymerization was continued for 1 hour while the temperature was raised to 50°C and stirring was continued at the same rotation speed. The polymerization conversion of styrene was 100%. Subsequently, while controlling the temperature to maintain 50 to 60°C, stirring was continued at the same rotation speed, and 4.87 kg of isoprene was continuously added to the reactor over 1 hour. After the addition of isoprene was completed, polymerization was continued for another 1 hour by continuing stirring at the same rotation speed. The polymerization conversion of isoprene was 100%. Next, while continuing to control the temperature to maintain 50 to 60°C and stirring at the same rotation speed, 0.73 kg of styrene was continuously added over 1 hour. After the addition of styrene was completed, polymerization was continued for another 1 hour by continuing stirring at the same rotation speed, and a triblock chain having an active end was formed. The polymerization conversion of styrene was 100%. Next, 48.1 mmol of methanol was added as a polymerization terminator and mixed to deactivate some of the active ends of the triblock chains having active ends, thereby forming a styrene-isoprene-styrene triblock copolymer (A). Thereafter, 1.41 kg of styrene was continuously added over 1 hour while continuing stirring at the same rotation speed and maintaining the temperature at 50-60°C. After the addition of styrene was completed, polymerization was continued for another 1 hour while continuing stirring at the same rotation speed, thereby forming a triblock chain having active ends. The polymerization conversion of styrene was 100%. Finally, 144 mmol of methanol was added as a polymerization terminator and mixed to deactivate all of the active ends of the triblock chains, thereby forming a styrene-isoprene-styrene triblock copolymer (E). A portion of the resulting reaction solution was removed and the block copolymer was evaluated according to the measurement methods described above. The results are shown in Table 2.

[0242] To 100 parts of the reaction liquid obtained as described above (containing 30 parts of the polymer component), 0.3 parts of 2,6-di-tert-butyl-p-cresol was added as an antioxidant 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, thereby obtaining a precipitate. This precipitate was pulverized and dried with hot air at 85°C, thereby recovering a styrene-isoprene block copolymer composition.

[0243] [Production Example 6] (Production of Styrene-Isoprene Block Copolymer Composition (6)) A reaction solution and a styrene-isoprene block copolymer composition were obtained in the same manner as in Production Example 1, except that the amounts of each raw material used were changed as shown in Table 1. The evaluation results are shown in Table 2.

[0244] [Production Example 7] (Production of Styrene-Isoprene Block Copolymer Composition (7)) A reaction solution and a styrene-isoprene block copolymer composition were obtained in the same manner as in Production Example 1, except that the amounts of each raw material used were changed as shown in Table 1. The evaluation results are shown in Table 2.

[0245]

[0246]

[0247] The properties of the polyolefin elastomers (F1) to (F4) used in the examples and comparative examples are shown in Table 3. The Shore A hardness was measured in accordance with JIS K 6253.

[0248]

[0249] Examples 1 to 10 and Comparative Examples 1 to 5 (Production of Elastomer Sheets) A styrene-isoprene block copolymer composition and a polyolefin-based elastomer were mixed in the weight ratios shown in Table 4 to prepare compositions. The resulting compositions were charged into a twin-screw extruder equipped with a T-die. Inside the twin-screw extruder, the components were heated, melted, and kneaded at 220°C, and then continuously extruded onto a chill roll for 20 minutes to continuously obtain elastomer sheets with an average thickness of 0.04 mm. The extrusion molding conditions were as follows:

[0250] (Extrusion molding conditions) Compound processing rate: 3 kg / hour Extruder temperature: Adjusted to 100°C at inlet and 220°C at T-die Screw: Twin screw with kneading zone Extruder L / D: 30 T-die: Width 200 mm, lip 0.4 mm Chill roll: Diameter 200 mm Film formation rate (chill roll transport rate): 6.0 m / min Nip roll 1 transport rate: 6.2 m / min Nip roll 2 transport rate: 7.5 m / min

[0251] (Production of composite sheet) The obtained elastomer sheet was transported to nip rolls 1 and 2 without being wound up. At this time, the transport speed of nip roll 1 was set to a speed 3% faster than the transport speed of the chill roll, thereby slightly stretching the elastomer sheet, and the transport speed of nip roll 2 was further set to a speed 25% faster than the transport speed of the chill roll, thereby elongating the elastomer sheet by 25% in the MD direction (the same as the extrusion direction during extrusion molding). In addition to the elastomer sheet, nip roll 2 was loaded with a nonwoven fabric (made of polypropylene, basis weight 20 g / m) as a first substrate and a second substrate. ２ ) was supplied. The tensile elongation of the nonwoven fabric measured under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 25°C was 10% or less. The nonwoven fabric, the elastomer sheet stretched by 25%, and the nonwoven fabric were layered in this order on nip roll 2. Next, while the elastomer sheet was maintained in a 25% stretched state, an ultrasonic bonding device was used to continuously bond the nonwoven fabric / elastomer sheet / nonwoven fabric, and simultaneously punch holes in the elastomer sheet to obtain a composite sheet. The obtained composite sheet was evaluated according to the above-mentioned method. The results are shown in Table 4.

[0252] The ultrasonic bonding device consists of a resonator (horn) and a receiving jig (anvil roll). The anvil roll has multiple convex portions (0.3 mm long in the MD direction, 3 mm wide in the TD direction) spaced at regular intervals on its outer circumferential surface. The convex portion pattern on the outer circumferential surface of the anvil roll is shown in Figure 2. By using an anvil roll with such convex portions, the ultrasonic energy is selectively concentrated at the locations where it is applied, causing localized fusion and perforation, resulting in a composite sheet with multiple 3 mm-wide holes. The resulting composite sheet was wound into a roll on a packaging roll and packaged.

[0253] (Manufacturing of Elastic Member) The obtained composite sheet was unwound and passed through a stretching device. The composite sheet was stretched in the MD direction (the same as the extrusion direction during extrusion molding) while machining the nonwoven fabrics (first and second substrates) constituting the composite sheet. This produced an elastic member. A pair of grooved rolls was used as the stretching device. The pitch between adjacent teeth (the distance between the center line of one tooth and the center line of the adjacent tooth) was 2 mm. The meshing depth (the overlap length between adjacent teeth when the grooved rolls are rotated meshed with each other) was 2.5 mm. The sheet was then machined and stretched at a stretch rate of 200%. The obtained elastic member was evaluated according to the above-mentioned method. The results are shown in Table 4.

[0254]

[0255] As is clear from Examples 1 to 10 in Table 4, the elastomer compositions of the present disclosure, which contain 15 to 100 wt % of a polyolefin elastomer having a Shore A hardness of 40 to 75 and 0 to 85 wt % of an aromatic vinyl block copolymer having an aromatic vinyl monomer unit content of 8 to 25 wt %, exhibited excellent moldability. Furthermore, by adhering an elastomer sheet made of the elastomer composition of the present disclosure to a substrate in a state stretched by 5 to 50%, a composite sheet was obtained that had a tensile elongation of 20% or less measured under specified conditions and exhibited excellent roll windability. Furthermore, by stretching the resulting composite sheet while mechanically processing it, an elastic member was obtained that had a tensile elongation of 100% or more measured under specified conditions. The resulting elastic member exhibited excellent elasticity. Thus, the polyolefin elastomer of the present disclosure was capable of producing a composite sheet suitable for roll packaging, which is suitable for use in producing elastic members.

[0256] On the other hand, when the content of the polyolefin elastomer was outside the range of 15 to 100% by weight, the tensile elongation was too large to obtain a composite sheet suitable for roll packaging (Comparative Examples 2 and 4).

[0257] Furthermore, even when the content of the polyolefin-based elastomer is within the range of 15 to 100% by weight, if the Shore A hardness of the polyolefin-based elastomer is too high or if the content of the aromatic vinyl monomer unit in the aromatic vinyl-based block copolymer is too high, the resulting elastomer sheet has poor moldability or the resulting elastic member has poor stretchability (Comparative Examples 1, 3, and 5).

[0258] REFERENCE SIGNS LIST 10 melt extrusion mechanism 11 cooling roll 13 drawing roll 14 drawing nip roll 15 first stretching roll 16 stretching nip roll 17 second stretching roll 20 stretching mechanism 30 lamination mechanism 40 melt 40a elastomer sheet 50 first substrate 60 second substrate 70 composite sheet 80 ultrasonic bonding machine

Claims

1. An elastomer composition for forming an elastomer sheet that constitutes a composite sheet comprising a substrate and an elastomer sheet laminated on the substrate, wherein the composite sheet is formed by adhering the elastomer sheet to the substrate in a state in which the elastomer sheet is stretched by 5 to 50%, and the tensile elongation of the composite sheet is 20% or less when a tensile test is conducted in the elongation direction at the time of adhesion under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C, the elastomer composition contains 15 to 100% by weight of a polyolefin elastomer and 0 to 85% by weight of an aromatic vinyl block copolymer, the polyolefin elastomer has a Shore A hardness of 40 to 75, and the aromatic vinyl block copolymer has an aromatic vinyl monomer unit content of 8 to 25% by weight.

2. The elastomer composition according to claim 1, wherein the composite sheet is stretched while being machined on the substrate to become an elastic member, and the tensile elongation of the elastic member measured in the elongation direction during adhesion under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C is 100% or more.

3. An elastomer composition according to claim 1 or 2, wherein the tensile elongation of the substrate measured under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 25°C is 10% or less.

4. The elastomer composition according to any one of claims 1 to 3, wherein the composite sheet comprises a first substrate and a second substrate as the substrates, and the composite sheet is a laminate formed by laminating the first substrate, the elastomer sheet, and the second substrate in this order.

5. The elastomer composition according to any one of claims 1 to 4, wherein the aromatic vinyl block copolymer is an aromatic vinyl-conjugated diene block copolymer.

6. The elastomer composition according to any one of claims 1 to 5, wherein the aromatic vinyl block copolymer contains a multi-branched copolymer having three or more branches.

7. The elastomer composition according to any one of claims 1 to 6, wherein the polyolefin elastomer contains ethylene units.

8. The elastomer composition according to claim 7, wherein the polyolefin elastomer further contains propylene units or octene units.

9. The elastomer composition according to any one of claims 1 to 8, wherein the weight average molecular weight of the aromatic vinyl block copolymer is 30,000 to 800,000.

10. An elastomer sheet formed from the elastomer composition according to any one of claims 1 to 9.

11. The elastomer sheet according to claim 10, which is an extrusion molded product of said elastomer composition.

12. The elastomer sheet according to claim 10 or 11, which has a thickness of 0.005 to 1 mm.

13. A composite sheet comprising a substrate and an elastomer sheet according to any one of claims 10 to 12 laminated on said substrate, wherein said elastomer sheet is bonded to said substrate in a state of being stretched by 5 to 50%, and wherein the composite sheet has a tensile elongation of 20% or less in the elongation direction when bonded, when a tensile test is carried out under conditions of a load of 2.5 N, a test piece width of 50 mm, and a temperature of 23°C.

14. The composite sheet according to claim 13, wherein the substrate is a nonwoven fabric.

15. An elastic member obtained by stretching the composite sheet according to claim 13 or 14 while subjecting the base material to mechanical processing, wherein the tensile elongation measured in the stretching direction during adhesion under conditions of a load of 10 N, a test piece width of 50 mm, and a temperature of 23°C is 100% or more.

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