Thermoplastic elastomer composition

Abstract

This thermoplastic elastomer composition contains a styrene polymer (A), a softening agent (B), and an olefin polymer (C), (A) contains a polymer (A1) and a polymer (A2), the polymer (A1) has a styrene polymer block (X1) and a conjugated diene compound polymer block (Y1), the (X1) forms a terminal of the polymer (A1), the proportion of structural units derived from 1, 2-vinyl bonds in the (Y1) is 50% by mass or more, and the polymer (A2) forms a conjugated diene compound polymer block (Y2). (A2) has two or more styrene polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2), (X2) forms a terminal of (A2), the proportion of a structural unit derived from a 1, 2-vinyl bond in (Y2) is less than 50% by mass, and when (A) is taken as 100 parts by mass, (B) is 80-300 parts by mass and (C) is 1-50 parts by mass; when (A) is 100 mass%, the total of (A1) and (A2) exceeds 50 mass%.

Description

Technical Field

[0001] The present invention relates to a thermoplastic elastomer composition. More specifically, the present invention relates to a thermoplastic elastomer composition containing two or more block copolymers having a styrenic polymer block and a conjugated diene compound polymer block. Background Art

[0002] When it takes time to inject a liquid such as a medicinal solution into a living body, a glass container or a plastic container is used as a container for holding the liquid. These containers are usually hung and used with the opening facing downward, and the opening is sealed with a medicine plug. The medicine plug is composed of, for example, a ring-shaped outer frame and an elastomer filled inside. In use, a metal or plastic insertion needle having a flow path is inserted through the elastomer to connect the inside and outside of the container, and the liquid inside the container can be taken out to the outside of the container. Conventionally, such a medicine plug uses a crosslinked rubber such as butyl rubber or styrene-butadiene rubber crosslinked with a sulfur crosslinking agent or the like. However, in recent years, a thermoplastic elastomer that does not use a crosslinking agent, has high hygiene, and has recyclability has been gradually used. As technologies related to such a medicine plug and the material for the medicine plug, the following Patent Documents 1 to 3 are known. Prior Art Documents

[0003] Patent Documents Patent Document 1: Japanese Patent Application Laid-Open No. 2007-169436 Patent Document 2: Japanese Patent Application Laid-Open No. 07-228749 Patent Document 3: Japanese Patent Application Laid-Open No. 2012-025944 Summary of the Invention Problems to be Solved by the Invention

[0004] In the above Patent Document 1, as a medical resin composition improved in liquid leakage resistance and resealability, a medical resin composition is disclosed, which comprises: (a) a block copolymer and / or a hydrogenated block copolymer composed of at least two polymer blocks A mainly composed of an aromatic vinyl compound having a specified Mw and at least one polymer block B mainly composed of a conjugated diene, (b) a hydrogenated petroleum resin and / or a phenylene ether-based resin, (c) a peroxide-decomposable olefin-based resin, and (d) a non-aromatic rubber softener.

[0005] In the above-mentioned Patent Document 2, as a medical rubber composition having excellent various physical properties such as resealability, needle puncturability, and rubber elasticity at high temperatures, etc., a medical resin composition is disclosed. In order to achieve a specified hardness, it contains, in a specified ratio: (a) a block copolymer composed of at least two polymer blocks A mainly composed of vinyl aromatic compounds and at least one polymer block B mainly composed of conjugated diene compounds, and having a number-average molecular weight of 150,000 or more, and / or a block copolymer obtained by hydrogenating the block copolymer and having a number-average molecular weight of 150,000 or more, (b) a polyolefin resin, and (c) a non-aromatic rubber softener.

[0006] In the above-mentioned Patent Document 3, as a medical rubber stopper having excellent needle puncture characteristics and good liquid leakage sealing property and sterilization stability, etc., a medical rubber stopper obtained by molding a resin composition is disclosed. The resin composition contains, in a specified ratio: (A) at least one of a block copolymer having at least two polymer blocks P mainly composed of vinyl aromatic compounds and at least one polymer block Q mainly composed of conjugated diene and a hydrogenated product thereof, (B) a hydrocarbon rubber softener, and (C) a polyolefin resin.

[0007] Among the various performances required for the above-mentioned medicine stopper, a performance of suppressing leakage of liquid from the through-hole formed in the elastomer after pulling out the insertion needle is required, that is, a liquid leakage suppressing effect. For this liquid leakage suppressing effect, the more the amount of the contained liquid, the more difficult it is to achieve. As described above, it is considered that this is because when the container is suspended and used, the more the amount of the contained liquid and / or its remaining amount, the higher the pressure from the inside of the container to the outside. Further, it is considered that the more the amount of the contained liquid, the longer the use time of the container, the longer the shaping time of the insertion needle on the through-hole formed in the elastomer, and the longer the time required for the through-hole to close after pulling out the insertion needle. In this regard, although Patent Documents 1 to 3 are technologies using a thermoplastic elastomer composition for a medicine stopper, since they are not designed assuming a large amount of residual liquid, and since they are not designed assuming a long insertion time of the insertion needle, there is a problem that it is difficult to sufficiently obtain the performances in these situations.

[0008] The present invention has been completed in view of the above problems, and an object thereof is to provide a thermoplastic elastomer composition capable of forming a medicine stopper having excellent liquid leakage suppressing effect for a container with a large amount of residual liquid and liquid leakage suppressing effect when the insertion needle is pulled out after being held for a long time without being pulled out. Means for Solving the Problems

[0009] That is, the present invention includes the following inventions. [1] A thermoplastic elastomer composition comprising a styrene-based polymer (A), a softener (B), and an olefin-based polymer (C), characterized in that The styrenic polymer (A) comprises a polymer (A1) and a polymer (A2). The polymer (A1) is a block copolymer having a styrenic polymer block (X1) and a conjugated diene compound polymer block (Y1). The styrenic polymer block (X1) forms at least one molecular terminal of the polymer (A1), and the proportion of the structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y1) is 50% by mass or more. The polymer (A2) is a block copolymer having two or more styrenic polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2). The styrenic polymer block (X2) forms at least one molecular terminal of the polymer (A2), and the proportion of the structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y2) is less than 50% by mass. When the styrenic polymer (A) is 100 parts by mass, the softening agent (B) is 80 to 300 parts by mass, and the olefinic polymer (C) is 1 to 50 parts by mass. When the styrenic polymer (A) is 100% by mass, the total of the polymer (A1) and the polymer (A2) exceeds 50% by mass. [2] The thermoplastic elastomer composition according to [1] above, wherein when the total of the polymer (A1) and the polymer (A2) is 100% by mass, the polymer (A1) is 5 to 90% by mass. [3] The thermoplastic elastomer composition according to [1] or [2] above, wherein The styrenic polymer (A) further comprises a polymer (A3). The polymer (A3) is a block copolymer having a styrenic polymer block (X3) and a conjugated diene compound polymer block (Y3). The number of the styrenic polymer blocks (X3) is two or less, and the proportion of the structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y3) is less than 50% by mass. [4] The thermoplastic elastomer composition according to [3] above, wherein when the total of the polymer (A2) and the polymer (A3) is 100% by mass, the polymer (A3) is 10 to 80% by mass. [5] The thermoplastic elastomer composition according to any one of [1] to [4] above, which further comprises a filler (D). When the styrenic polymer (A) is 100 parts by mass, the filler (D) is 0.5 to 100 parts by mass. Advantages of the Invention

[0010] The thermoplastic elastomer composition according to the present invention can provide a suppository having excellent effects of suppressing liquid leakage from a container with a large amount of residual liquid and suppressing liquid leakage when a puncture needle is pulled out after being held without being pulled out for a long time. Detailed Embodiments

[0011] Hereinafter, the present invention will be described based on specific embodiments. However, the present invention is not limited to these embodiments. These embodiments are merely examples shown for the convenience of explanation, and the present invention is not limited thereto in any sense, and various modifications can be made to the present invention according to the purpose and use. In addition, all publications, patents, and patent applications cited in this specification are incorporated herein by reference in their entirety.

[0012] In addition, in this specification, when a numerical range is expressed as "XX to YY", it means "XX or more and YY or less". In addition, in this specification, the molecular weight is the molecular weight in terms of polystyrene measured by gel permeation chromatography (hereinafter also referred to as GPC). In the molecular weight, the weight-average molecular weight is sometimes denoted as Mw, and the number-average molecular weight is sometimes denoted as Mn.

[0013] The thermoplastic elastomer composition of the present invention contains a styrenic polymer (A), a softening agent (B), and an olefinic polymer (C). In this specification, the styrenic polymer (A), the softening agent (B), and the olefinic polymer (C) will be described in turn below.

[0014] (1) Styrenic polymer (A) The styrenic polymer (A) contains a styrenic polymer (A1) and a polymer (A2). That is, the styrenic polymer (A) is a mixture of the polymer (A1) and the polymer (A2). The styrenic polymer (A) may not contain other polymers except the polymer (A1) and the polymer (A2). As other polymers, for example, the polymer (A3) may be included as described later.

[0015] (2) Polymer (A1) The polymer (A1) is a block copolymer having a styrene-based polymer block (X1) and a conjugated diene-based compound polymer block (Y1). From the viewpoint of having a styrene-based polymer block (X1), the polymer (A1) can also be referred to as a styrene-based polymer (A1). The polymer (A1) may be a non-hydride, but from the viewpoints of heat resistance and mechanical strength, a hydride is preferred. That is, a hydrogenated styrene-based polymer is preferred. When the polymer (A1) is a hydride, the hydrogenation rate is not limited, and it may be 80% or more, it may be 90% or more, and it may be 100% or less. Since hydrogenation acts on the conjugated diene-based compound polymer block (Y1) in the polymer (A1), the hydrogenation rate is determined by comparing the content ratio of carbon-carbon double bonds in the polymer (A1) before hydrogenation and the polymer (A1) after hydrogenation. In addition, the content ratio of carbon-carbon double bonds can be measured by 1 1H-NMR analysis using a nuclear magnetic resonance apparatus (manufactured by Varian, model "INOVA AS600", etc.). It should be noted that the above-mentioned hydrogenated polymer (A1) can also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrene-based polymer, or a hydrogenated styrene-based copolymer.

[0016] In the thermoplastic elastomer composition of the present invention, by containing the polymer (A1), there is a tendency to improve the liquid leakage inhibition performance compared with the case where it is not contained or contained in a small amount. The reason is not clear, but by containing the polymer (A1), compared with the case where the polymer (A1) is not contained or contained in a small amount, there are the following tendencies: low hardness, small MFR, large tensile strength, large elongation at break, and large tear strength. Therefore, it is considered that these characteristics contribute. In particular, the improvement of mechanical strength such as tensile strength, elongation at break, and tear strength may contribute to the improvement of the liquid leakage inhibition performance. Specifically, it is considered that, as described later in the examples, when a needle pierces the plug body, cracks are less likely to occur in the thermoplastic elastomer composition constituting the whole around the intrusion of the needle. In addition, in the thermoplastic elastomer composition of the present invention, by containing the polymer (A1), the softening agent (B) can effectively function, and thus the moldability can be improved.

[0017] The content ratio of the styrene-based monomer units of the polymer (A1) is not limited. When the entire polymer (A1) is set to 100% by mass, the content ratio of the styrene-based monomer units of the polymer (A1) can be 5% by mass or more, further 7% by mass or more, further 10% by mass or more, and further 15% by mass or more. On the other hand, it can be 90% by mass or less, further 70% by mass or less, further 60% by mass or less, and further 50% by mass or less. The above upper and lower limits can be combined with each other. For example, it can be 5 to 90% by mass, further 7 to 70% by mass, further 10 to 60% by mass, and further 15 to 50% by mass. When the content ratio of the styrene-based monomer units is within the above range, appropriate flexibility, heat resistance, and mechanical strength can be obtained.

[0018] It should be noted that the content ratio of the styrene-based monomer units can be measured by 1H-NMR analysis using a nuclear magnetic resonance apparatus (manufactured by BRUKER Corporation, model "DPX-400", etc.). That is, it can be calculated based on the signals of the hydrogen atoms of the benzene rings of styrene and styrene derivatives. 1 That is, it can be calculated based on the signals of the hydrogen atoms of the benzene rings of styrene and styrene derivatives.

[0019] The Mw of the polymer (A1) is not limited and can be 50,000 to 500,000, further 70,000 to 400,000, and further 100,000 to 260,000. In addition, the Mn of the polymer (A1) is not limited and can be 40,000 to 500,000, further 60,000 to 400,000, and further 80,000 to 260,000. Furthermore, the Mw / Mn of the polymer (A1) is not limited and can be 1.00 to 1.30, further 1.03 to 1.17, and further 1.06 to 1.12. Within these ranges, a thermoplastic elastomer composition having excellent moldability and heat resistance can be easily obtained. Therefore, it is easy to mold and is preferably used in heat treatment operations such as sterilization treatment.

[0020] It should be noted that the Mw (weight average molecular weight) and Mn (number average molecular weight) of the polymer (A1) can be measured by gel permeation chromatography. Its operation can be as described below. ·GPC apparatus (manufactured by Tosoh Corporation, model "Auto Sampler AS-8010") ·Pump (manufactured by JASCO Corporation, model "PU-980") ·Column oven (manufactured by Showa Denko K.K., model "AO-50") ·Chromatographic column (manufactured by Showa Denko K.K., model "K-805L (8.0 × 300 mm)" 1 piece and model "K-804L (8.0 × 300 mm)" 1 piece are used in series) · RI (Differential Refractometer) detector (manufactured by Hitachi, Ltd., model "L-3300") · Guard column: K-G (4.6×10 mm) · Column temperature: 40 °C · Eluent: chloroform · Eluent flow rate: 1.0 ml / min · Sample concentration: approximately 1 mg / ml · Sample solution filtration: disposable filter with a pore size of 0.45 μm made of polytetrafluoroethylene · Standard for calibration curve: polystyrene (manufactured by Showa Denko K.K.)

[0021] It should be noted that the polymer (A1) may have polar functional groups such as carboxyl groups, hydroxyl groups, acid anhydride groups, amino groups, and epoxy groups in the molecular chain and / or at the molecular terminals as needed. They can be used alone or in combination of two or more kinds.

[0022] (2-1) Styrenic polymer block (X1) The styrenic polymer block (X1) is a polymer block having styrenic monomer units as the main structural units. The styrenic monomer units are structural units having styrene and / or styrene derivatives as monomers. Among them, as styrene derivatives, for example, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, p-tert-butylstyrene, etc. can be cited. They can be used alone or in combination of two or more kinds.

[0023] In the styrenic monomer units constituting the styrenic polymer block (X1), the proportion of units derived from styrene (units not derived from styrene derivatives) is not limited, but relative to the entire styrenic polymer block (X1), it can be 50% by mass or more, can be further 80% by mass or more, can be further 90% by mass or more, can be further 95% by mass or more, and usually can be 100% by mass or less. When the styrenic polymer block (X1) contains other structural units in addition to styrenic monomer units, the monomers forming the other structural units are not limited. For example, acrylonitrile, methacrylate, etc. can be cited. They can be used alone or in combination of two or more kinds.

[0024] In addition, the styrene-based polymer block (X1) may form at least one molecular end of the polymer (A1). The polymer (A1) may be a linear polymer without main-chain branches or a branched polymer with main-chain branches. They may be used alone or in combination of two or more. Among them, as a mode in which the polymer (A1) is a linear polymer and the styrene-based polymer block (X1) forms only one molecular end, examples include: "X1-Y1", "X1-Y1-X1-Y1", "X1-Y1-X1-Y1-X1-Y1", etc. They may be used alone or in combination of two or more.

[0025] In addition, as a mode in which the polymer (A1) is a linear polymer and the styrene-based polymer block (X1) forms two molecular ends, examples include: "X1-Y1-X1", "X1-Y1-X1-Y1-X1", "X1-Y1-X1-Y1-X1-Y1-X1", etc. That is, various polymers in which non-hydrides are collectively referred to as SBS and hydrides are collectively referred to as SEBS can be cited. They may be used alone or in combination of two or more. In addition, in the case where the polymer (A1) is a branched polymer, it may include a mode in which the styrene-based polymer block (X1) forms three or more molecular ends. That is, at least one molecular end of the polymer (A1) is formed by the styrene-based polymer block (X1), and more than half of the blocks constituting the polymer (A1) are styrene-based polymer blocks (X1).

[0026] It should be noted that in the above "X1-Y1-X1-Y1", "X1-Y1-X1-Y1-X1-Y1", "X1-Y1-X1", "X1-Y1-X1-Y1-X1", "X1-Y1-X1-Y1-X1-Y1-X1", etc., for the sake of convenience, each X1 represents the styrene-based polymer block (X1), and it does not mean that each X1 is the same styrene-based polymer block. In the polymer (A1), each X1 may be the same or different. The same applies to each Y1. In addition, the styrene-based polymer block (X1) may be the same as or different from the styrene-based polymer block (X2) and the styrene-based polymer block (X3) described later.

[0027] (2-2) Conjugated diene compound polymer block (Y1) The polymer block (Y1) of a conjugated diene compound is a polymer block having monomer units of a conjugated diene compound as main structural units. The monomer units of the conjugated diene compound are structural units having a conjugated diene and / or a conjugated diene derivative as a monomer. Among them, as the conjugated diene, examples include: butadiene (1,3-butadiene, 1,2-butadiene), isoprene (2-methyl-1,3-butadiene), 1,3-pentadiene, etc. They may be used alone or in combination of two or more. In the thermoplastic elastomer composition of the present invention, as the conjugated diene compound monomer forming the polymer block (Y1) of the conjugated diene compound, it contains at least a structural unit derived from 1,3-butadiene. Further, the polymer block (Y1) of the conjugated diene compound is preferably a polymer block having 1,3-butadiene monomer units as main structural units.

[0028] The proportion of the monomer units of the conjugated diene compound constituting the polymer block (Y1) of the conjugated diene compound is not limited, and may be 50% by mass or more, further may be 80% by mass or more, further may be 90% by mass or more, further may be 95% by mass or more, and usually may be 100% by mass or less with respect to the whole of the polymer block (Y1) of the conjugated diene compound. When the polymer block (Y1) of the conjugated diene compound contains other structural units in addition to the monomer units of the conjugated diene compound, the monomers forming the other structural units are not limited. For example, examples include: butene, isobutene, pentene, hexene, 5-ethylidene-2-norbornene, 1,4-hexadiene, etc. They may be used alone or in combination of two or more.

[0029] As described above, the polymer block (Y1) of the conjugated diene compound contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer units may be units having a 1,2-vinyl bond [i.e., -CH2-CH(CH=CH2)-], or may be units having a 1,4-vinyl bond (including a cis-1,4-bond and a trans-1,4-bond) [i.e., -CH2-CH=CH-CH2-]. They may be used alone or in combination of two or more, but in the present invention, the polymer block (Y1) of the conjugated diene compound is a block in which the proportion of the structural units having a 1,2-vinyl bond is 50% by mass or more. In addition, the structural units having a 1,4-vinyl bond and the structural units having a 1,2-vinyl bond in the polymer block (Y1) of the conjugated diene compound may not be hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural units having a 1,2-vinyl bond" are structural units derived from monomers having a 1,2-vinyl bond, and mean structural units including both non-hydrogenated structural units and hydrogenated structural units.

[0030] That is, the proportion of the structural units derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y1) is preferably 50% by mass or more, more preferably 52% by mass or more, still more preferably 54% by mass or more, further preferably 56% by mass or more, and particularly preferably 58% by mass or more when the total of the units derived from 1,3-butadiene monomer is set to 100% by mass. The upper limit is not limited and can be 100% by mass. For example, it can be 90% by mass or less, 85% by mass or less, or 80% by mass or less. The above upper and lower limits can be combined with each other. For example, it can be 52 to 100% by mass, further 54 to 90% by mass, further 56 to 85% by mass, or further 58 to 80% by mass.

[0031] It should be noted that the proportion of the structural units derived from the 1,2-vinyl bond can be measured by 1H-NMR analysis using a nuclear magnetic resonance apparatus (manufactured by JEOL Ltd., model "JNM-Lambda 500", etc.). 1 Specifically, the block copolymer before hydrogenation is dissolved in CDCl3, and the 1H-NMR spectrum (measurement temperature: 50 °C) is measured to obtain the peak area corresponding to the structural units derived from the 1,4-vinyl bond of 1,3-butadiene and the peak area corresponding to the structural units derived from the 1,2-vinyl bond of the butadiene unit. Then, it can be calculated by dividing the peak area value of the 1,2-vinyl bond by the sum of the peak areas of the 1,4-vinyl bond and the 1,2-vinyl bond. 1

[0032] (3) Polymer (A2) Polymer (A2) is a block copolymer having two or more styrene-based polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2). From the viewpoint that polymer (A2) has a styrene-based polymer block (X2), polymer (A2) can also be referred to as styrene-based polymer (A2). This polymer (A2) can be a non-hydrogenated product, but from the viewpoints of heat resistance and mechanical strength, a hydrogenated product is preferred. That is, a hydrogenated styrene-based polymer is preferred. When polymer (A2) is a hydrogenated product, the hydrogenation rate is not limited and can be 80% or more, 90% or more, or 100% or less. Since hydrogenation acts on the conjugated diene compound polymer block (Y2) in polymer (A2), the hydrogenation rate is determined by comparing the carbon-carbon double bond content ratio of polymer (A2) before hydrogenation and polymer (A2) after hydrogenation. In addition, the carbon-carbon double bond content ratio can be measured by 13C-NMR analysis using a nuclear magnetic resonance apparatus (manufactured by VARIAN Inc., model "INOVA AS600", etc.). 1It is determined by 1H-NMR analysis. It should be noted that the above hydrogenated polymer (A2) can also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrenic polymer, or a hydrogenated styrenic copolymer.

[0033] In the thermoplastic elastomer composition of the present invention, by containing the polymer (A2), compared with the case where the polymer (A2) is not contained, there is a tendency to improve the liquid leakage inhibition performance and the needle holding performance (needle holding time). The reason is not clear yet, but by containing the polymer (A2), compared with the case where the polymer (A2) is not contained or the content is less, there are the following tendencies: small MFR, large tensile strength, large elongation at break, and large tear strength. Therefore, it is considered that these properties contribute.

[0034] The content ratio of the styrenic monomer unit of the polymer (A2) is not limited. When the whole polymer (A2) is set to 100% by mass, it can be 5% by mass or more, can be further 5% by mass or more, can be further 10% by mass or more, can be further 15% by mass or more, can be further 20% by mass or more. On the other hand, it can be 95% by mass or less, can be further 85% by mass or less, can be further 75% by mass or less, can be further 65% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 5 to 95% by mass, can be further 10 to 85% by mass, can be further 15 to 75% by mass, can be further 20 to 65% by mass. When the content ratio of the styrenic monomer unit is within the above range, appropriate flexibility, heat resistance, and mechanical strength can be obtained. It should be noted that the content ratio of the styrenic monomer unit can be measured in the same manner as the method described for the polymer (A1).

[0035] The Mw of the polymer (A2) is not limited and can be 50,000 to 500,000, can be further 70,000 to 400,000, can be further 100,000 to 300,000. In addition, the Mn of the polymer (A2) is not limited and can be 40,000 to 500,000, can be further 60,000 to 400,000, can be further 80,000 to 280,000. Furthermore, the Mw / Mn of the polymer (A2) is not limited and can be 1.00 to 1.30, can be further 1.03 to 1.17, can be further 1.06 to 1.12. Within these ranges, it is easy to obtain a thermoplastic elastomer composition having excellent moldability and heat resistance. Therefore, it is easy to mold and is preferably used in heating operations such as sterilization treatment. It should be noted that the Mw (weight average molecular weight) and Mn (number average molecular weight) of the polymer (A2) can be measured by gel permeation chromatography. The operation can be the same as that of the polymer (A1).

[0036] It should be noted that the polymer (A2) may have polar functional groups such as carboxyl groups, hydroxyl groups, acid anhydride groups, amino groups, and epoxy groups in the molecular chain and / or at the molecular terminals as required. One type or two or more types thereof can be used alone.

[0037] (3-1) Styrenic polymer block (X2) The styrenic polymer block (X2) is a polymer block having styrenic monomer units as the main structural units. The styrenic monomer units are structural units having styrene and / or styrene derivatives as monomers. Among them, examples of the styrene derivatives include: α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, p-tert-butylstyrene, and the like. One type or two or more types thereof can be used alone.

[0038] In the styrenic monomer units constituting the styrenic polymer block (X2), the proportion of the units derived from styrene (units not derived from styrene derivatives) is not limited, and relative to the whole of the styrenic polymer block (X2), it can be 50% by mass or more, can be further 80% by mass or more, can be further 90% by mass or more, can be further 95% by mass or more, and usually can be 100% by mass or less. When the styrenic polymer block (X2) contains other structural units in addition to the styrenic monomer units, the monomers forming the other structural units are not limited, and examples thereof include acrylonitrile, methacrylate, and the like. One type or two or more types thereof can be used alone.

[0039] In addition, the polymer (A2) has two or more styrenic polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2), and the styrenic polymer block (X2) forms at least one molecular terminal of the polymer (A2). The polymer (A2) can be a linear polymer having no main chain branches or a branched polymer having main chain branches. One type or two or more types thereof can be used alone. Among them, when the polymer (A2) is a linear polymer, the polymer (A2) has the same number of styrenic polymer blocks (X2) and conjugated diene compound polymer blocks (Y2), or can be in such a way that the number of styrenic polymer blocks (X2) is one more than the number of conjugated diene compound polymer blocks (Y2), whereby the styrenic polymer block (X2) forms at least one molecular terminal of the polymer (A2).

[0040] That is, examples of the form having the same number of styrene-based polymer blocks (X2) and conjugated diene-based compound polymer blocks (Y2) include: a structure of “X2-Y2-X2-Y2” having 2 styrene-based polymer blocks (X2) and 2 conjugated diene-based compound polymer blocks (Y2), a structure of “X2-Y2-X2-Y2-X2-Y2” having 3 styrene-based polymer blocks (X2) and 3 conjugated diene-based compound polymer blocks (Y2), etc. They can be used alone or in combination of two or more.

[0041] In addition, examples of the form in which the number of styrene-based polymer blocks (X2) is 1 more than the number of conjugated diene-based compound polymer blocks (Y2) include: a structure of “X2-Y2-X2-Y2-X2” having 3 styrene-based polymer blocks (X2) and 2 conjugated diene-based compound polymer blocks (Y2), a structure of “X2-Y2-X2-Y2-X2-Y2-X2” having 4 styrene-based polymer blocks (X2) and 3 conjugated diene-based compound polymer blocks (Y2), etc. That is, various polymers in which non-hydrides are collectively referred to as SBS and hydrides are collectively referred to as SEBS are exemplified. They can be used alone or in combination of two or more. That is, by forming at least one molecular end of the polymer (A2) with the styrene-based polymer block (X2), more than half of the blocks constituting the polymer (A2) are styrene-based polymer blocks (X2).

[0042] It should be noted that in the above “X2-Y2-X2-Y2”, “X2-Y2-X2-Y2-X2-Y2”, “X2-Y2-X2-Y2-X2”, “X2-Y2-X2-Y2-X2-Y2-X2”, etc., for convenience, each X2 represents a styrene-based polymer block (X2), but it does not mean that each X2 is the same styrene-based polymer block. In the polymer (A2), each X2 can be the same or different. The same applies to each Y2. In addition, the styrene-based polymer block (X2) can be the same as or different from the aforementioned styrene-based polymer block (X1) and the styrene-based polymer block (X3) described later.

[0043] (3-2) Conjugated diene-based compound polymer block (Y2) The polymer block (Y2) of a conjugated diene compound is a polymer block having monomer units of a conjugated diene compound as main structural units. The monomer units of a conjugated diene compound are structural units having a conjugated diene and / or a conjugated diene derivative as a monomer. Among them, as the conjugated diene, examples include: butadiene (1,3-butadiene, 1,2-butadiene), isoprene (2-methyl-1,3-butadiene), 1,3-pentadiene, etc. They may be used alone or in combination of two or more. In the thermoplastic elastomer composition of the present invention, as the conjugated diene compound monomer forming the polymer block (Y2) of a conjugated diene compound, it contains at least a structural unit derived from 1,3-butadiene. Further, the polymer block (Y2) of a conjugated diene compound is preferably a polymer block having 1,3-butadiene monomer units as main structural units.

[0044] The proportion of the monomer units of a conjugated diene compound constituting the polymer block (Y2) of a conjugated diene compound is not limited, and may be 50% by mass or more, further may be 80% by mass or more, further may be 90% by mass or more, further may be 95% by mass or more, and generally may be 100% by mass or less with respect to the whole of the polymer block (Y2) of a conjugated diene compound. When the polymer block (Y2) of a conjugated diene compound contains other structural units in addition to the monomer units of a conjugated diene compound, the monomer forming the other structural units is not limited, and examples include: butene, isobutene, pentene, hexene, 5-ethylidene-2-norbornene, 1,4-hexadiene, etc. They may be used alone or in combination of two or more.

[0045] As described above, the polymer block (Y2) of a conjugated diene compound contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer units may be units having a 1,2-vinyl bond [i.e., -CH2-CH(CH=CH2)-], or may be units having a 1,4-vinyl bond (including a cis-1,4-bond and a trans-1,4-bond) [i.e., -CH2-CH=CH-CH2-]. They may be used alone or in combination of two or more, but in the present invention, the polymer block (Y2) of a conjugated diene compound is a block in which the proportion of the structural units having a 1,2-vinyl bond is less than 50% by mass. In addition, the structural units having a 1,4-vinyl bond and the structural units having a 1,2-vinyl bond in the polymer block (Y2) of a conjugated diene compound may not be hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural units having a 1,2-vinyl bond" are structural units having a 1,2-vinyl bond monomer, and mean structural units including both non-hydrogenated structural units and hydrogenated structural units.

[0046] That is, the proportion of the structural units derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y2) is less than 50% by mass, preferably 47% or less, more preferably 43% or less, still more preferably 38% or less, and particularly preferably 35% or less, when the units derived from 1,3-butadiene monomer are taken as 100% by mass in total. There is no limitation on its lower limit, which may be 0% by mass or more, for example, 5% by mass or more, 10% by mass or more, 15% by mass or more, or 20% by mass or more. The above upper and lower limits may be combined with each other. For example, it may be 0% by mass or more and less than 50% by mass, further 10 to 47% by mass, further 15 to 43% by mass, further 15 to 38% by mass, or further 20 to 35% by mass. It should be noted that the proportion of the structural units derived from the 1,2-vinyl bond can be measured in the same manner as the method described for the polymer (A1).

[0047] (4) Polymer (A3) In the present invention, the styrenic polymer (A) may further contain a polymer (A3) in addition to the above polymers (A1) and (A2). The polymer (A3) is a block copolymer having a styrenic polymer block (X3) and a conjugated diene compound polymer block (Y3). From the viewpoint that the polymer (A3) has a styrenic polymer block (X3), the polymer (A3) may also be referred to as a styrenic polymer (A3). This polymer (A3) may be a non-hydrogenated product, but from the viewpoints of heat resistance and mechanical strength, a hydrogenated product is preferred. That is, a hydrogenated styrenic polymer is preferred. When the polymer (A3) is a hydrogenated product, the hydrogenation rate is not limited and may be 80% or more, 90% or more, or 100% or less. Since hydrogenation acts on the conjugated diene compound polymer block (Y3) in the polymer (A3), the hydrogenation rate is determined by comparing the content ratios of carbon-carbon double bonds in the polymer (A3) before and after hydrogenation. In addition, the content ratio of carbon-carbon double bonds can be measured by 1H-NMR analysis using a nuclear magnetic resonance apparatus (manufactured by VARIAN, model "INOVA AS600", etc.). It should be noted that the above hydrogenated polymer (A3) may also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrenic polymer, or a hydrogenated styrenic copolymer. 1 1H-NMR analysis. It should be noted that the above hydrogenated polymer (A3) may also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrenic polymer, or a hydrogenated styrenic copolymer.

[0048] In the thermoplastic elastomer composition of the present invention, when the polymer (A3) is contained, the needle holding performance (needle holding time) tends to be improved compared to the case where the polymer (A3) is not contained. The reason is not clear yet, but by containing the polymer (A3), compared to the case where the polymer (A3) is not contained or the amount thereof contained is small, the MFR tends to decrease and the elongation at break tends to increase. Therefore, it is considered that these characteristics contribute to it.

[0049] The content ratio of the styrene-based monomer unit of the polymer (A3) is not limited. When the whole polymer (A3) is set to 100% by mass, it can be 5% by mass or more, can further be 10% by mass or more, can further be 15% by mass or more, can further be 20% by mass or more. On the other hand, it can be 90% by mass or less, can further be 70% by mass or less, can further be 60% by mass or less, can further be 50% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 5 to 90% by mass, can further be 10 to 70% by mass, can further be 15 to 60% by mass, can further be 20 to 50% by mass. When the content ratio of the styrene-based monomer unit is within the above range, appropriate flexibility, heat resistance, and mechanical strength can be obtained. It should be noted that the content ratio of the styrene-based monomer unit can be measured in the same manner as the method described for the polymer (A1).

[0050] The Mw of the polymer (A3) is not limited and can be 50,000 to 500,000, can further be 100,000 to 450,000, can further be 200,000 to 350,000. In addition, the Mn of the polymer (A3) is not limited and can be 40,000 to 500,000, can further be 80,000 to 450,000, can further be 160,000 to 350,000. Furthermore, the Mw / Mn of the polymer (A3) is not limited and can be 1.00 to 1.60, can further be 1.02 to 1.40, can further be 1.05 to 1.30. Within these ranges, it is easy to obtain a thermoplastic elastomer composition having excellent moldability and heat resistance. Therefore, it is easy to mold and is preferably used in heating operations such as sterilization treatment. It should be noted that the Mw (weight average molecular weight) and Mn (number average molecular weight) of the polymer (A3) can be measured by gel permeation chromatography. The operation can be the same as that for the polymer (A1).

[0051] It should be noted that the polymer (A3) may have polar functional groups such as carboxyl group, hydroxyl group, acid anhydride group, amino group, and epoxy group in the molecular chain and / or at the molecular end as needed. They can be used alone or in combination of two or more.

[0052] (4-1) Styrenic polymer block (X3) The styrenic polymer block (X3) is a polymer block mainly composed of styrenic monomer units. The styrenic monomer units are structural units with styrene and / or styrene derivatives as monomers. Among them, as styrene derivatives, for example, α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, p-tert-butylstyrene, etc. can be cited. They can be used alone or in combination of two or more kinds.

[0053] In the styrenic monomer units constituting the styrenic polymer block (X3), the proportion of units derived from styrene (units not derived from styrene derivatives) is not limited, and relative to the whole styrenic polymer block (X3), it can be 50% by mass or more, can be further 80% by mass or more, can be further 90% by mass or more, can be further 95% by mass or more, and usually can be 100% by mass or less. When the styrenic polymer block (X3) contains other structural units in addition to styrenic monomer units, the monomers forming the other structural units are not limited. For example, acrylonitrile, methacrylate, etc. can be cited. They can be used alone or in combination of two or more kinds.

[0054] In addition, the polymer (A3) has 2 or less styrenic polymer blocks (X3). The polymer (A3) can be a linear polymer without main chain branches or a branched polymer with main chain branches. They can be used alone or in combination of two or more kinds. Among them, when the polymer (A3) is a linear polymer, as its structure, “X3-Y3”, “X3-Y3-X3”, “X3-Y3-X3-Y3”, etc. can be cited. That is, various polymers such as those collectively called SBS for non-hydrogenated products and SEBS for hydrogenated products can be cited. They can be used alone or in combination of two or more kinds.

[0055] It should be noted that in the above “X3-Y3-X3”, “X3-Y3-X3-Y3”, etc., for the sake of convenience, each X3 represents the styrenic polymer block (X3), and it does not mean that each X3 is the same styrenic polymer block. In the polymer (A3), each X3 can be the same or different. The same applies to each Y3. In addition, the styrenic polymer block (X3) can be the same as or different from the above-mentioned styrenic polymer blocks (X1) and (X2).

[0056] (4-2) Conjugated diene compound polymer block (Y3) The polymer block (Y3) of a conjugated diene compound is a polymer block mainly composed of monomer units of a conjugated diene compound. The monomer unit of a conjugated diene compound is a structural unit with a conjugated diene and / or a conjugated diene derivative as a monomer. Among them, as the conjugated diene, examples include: butadiene (1,3-butadiene, 1,2-butadiene), isoprene (2-methyl-1,3-butadiene), 1,3-pentadiene, etc. They can be used alone or in combination of two or more. In the thermoplastic elastomer composition of the present invention, as the conjugated diene compound monomer forming the polymer block (Y3) of a conjugated diene compound, it contains at least a structural unit derived from 1,3-butadiene. Further, the polymer block (Y2) of a conjugated diene compound is preferably a polymer block mainly composed of 1,3-butadiene monomer units.

[0057] The proportion of the monomer unit of the conjugated diene compound constituting the polymer block (Y3) of a conjugated diene compound is not limited, and relative to the whole polymer block (Y3) of a conjugated diene compound, it can be 50% by mass or more, can be further 80% by mass or more, can be further 90% by mass or more, can be further 95% by mass or more, and usually can be 100% by mass or less. When the polymer block (Y3) of a conjugated diene compound contains other structural units in addition to the monomer unit of a conjugated diene compound, the monomer forming the other structural unit is not limited. For example, examples include: butene, isobutene, pentene, hexene, 5-ethylidene-2-norbornene, 1,4-hexadiene, etc. They can be used alone or in combination of two or more.

[0058] As described above, the polymer block (Y3) of a conjugated diene compound contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer unit can be a unit with a 1,2-vinyl bond [i.e., -CH2-CH(CH=CH2)-], or can be a unit with a 1,4-vinyl bond (including cis-1,4-bond and trans-1,4-bond) [i.e., -CH2-CH=CH-CH2-]. They can be used alone or in combination of two or more, but in the present invention, the polymer block (Y3) of a conjugated diene compound is a block in which the proportion of the structural unit from the 1,2-vinyl bond is less than 50% by mass. In addition, the structural unit from the 1,4-vinyl bond and the structural unit from the 1,2-vinyl bond in the polymer block (Y3) of a conjugated diene compound can be non-hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural unit from the 1,2-vinyl bond" is a structural unit from a monomer with a 1,2-vinyl bond, and means a structural unit including both non-hydrogenated structural units and hydrogenated structural units.

[0059] That is, the proportion of the structural units derived from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y3) is less than 50% by mass, preferably 47% by mass or less, more preferably 45% by mass or less, still more preferably 43% by mass or less, and particularly preferably 40% by mass or less, when the units derived from 1,3-butadiene monomers are taken as 100% by mass in total. The lower limit is not limited and may be 0% by mass or more, for example, it may be 0% by mass or more, it may be 10% by mass or more, it may be 25% by mass or more, it may be 35% by mass or more. The above upper and lower limits may be combined with each other. For example, it may be 0% by mass or more and less than 50% by mass, may further be 5 to 47% by mass, may further be 10 to 45% by mass, may further be 25 to 43% by mass, may further be 35 to 40% by mass. It should be noted that the proportion of the structural units derived from 1,2-vinyl bonds can be measured in the same manner as the method described for the polymer (A1).

[0060] (5) Proportion of the polymers (A1) to (A3) As described above, the styrene-based polymer (A) has at least the polymers (A1) and (A2). When the styrene-based polymer (A) is taken as 100% by mass, the total of the polymers (A1) and (A2) exceeds 50% by mass. By making the styrene-based polymer (A) contain in total more than 50% by mass of the polymers (A1) and (A2), a thermoplastic elastomer composition capable of forming a suppository can be obtained, and the suppository is excellent in the effect of suppressing liquid leakage from a container with a large amount of residual liquid and the effect of suppressing liquid leakage when the insertion needle is pulled out after being inserted for a long time.

[0061] The total content ratio of the polymer (A1) and the polymer (A2) can further be 51% by mass or more, can further be 52% by mass or more, can further be 53% by mass or more, can further be 54% by mass or more, can further be 55% by mass or more, can further be 60% by mass or more, can further be 65% by mass or more, can further be 70% by mass or more. On the other hand, the upper limit of the total content ratio of the polymer (A1) and the polymer (A2) is not limited and can be 100% by mass or less. The total content ratio can further be 99% by mass or less, can further be 98% by mass, can further be 95% by mass, can further be 90% by mass, can further be 87% by mass, can further be 85% by mass, can further be 80% by mass. The above upper and lower limits can be combinations of each other. For example, it can exceed 50% by mass and be 100% by mass or less, can further be 51 - 100% by mass, can further be 51 - 99% by mass, can further be 53 - 99% by mass, can further be 53 - 95% by mass, can further be 55 - 95% by mass, can further be 55 - 90% by mass, can further be 51 - 90% by mass, can further be 53 - 90% by mass, can further be 53 - 85% by mass, can further be 55 - 85% by mass, can further be 55 - 80% by mass. In each of the above ranges, as the range narrows, the liquid leakage suppressing performance tends to improve.

[0062] In addition, when the total of the polymer (A1) and the polymer (A2) is set to 100% by mass, the ratio of the polymer (A1) is not limited. For example, it can be 1% by mass or more, can further be 5% by mass or more, can further be 10% by mass or more, can further be 15% by mass or more, can further be 20% by mass or more, can further be 25% by mass or more. The upper limit of this ratio is not limited and can further be 95% by mass or less, can further be 90% by mass or less, can further be 85% by mass or less, can further be 80% by mass or less, can further be 75% by mass or less, can further be 70% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 10 - 85% by mass, can further be 15 - 85% by mass, can further be 15 - 80% by mass, can further be 20 - 80% by mass, can further be 20 - 75% by mass, can further be 25 - 75% by mass, can further be 25 - 70% by mass. In each of the above ranges, as the range narrows, there is a tendency to improve the liquid leakage suppressing performance and the needle holding performance (needle holding time).

[0063] Furthermore, when the styrenic polymer (A) contains three types of polymers, namely polymer (A1), polymer (A2), and polymer (A3), when the total of polymer (A2) and polymer (A3) is set to 100% by mass, the proportion of polymer (A3) is not limited. For example, it can be further 10% by mass or more, can be further 15% by mass or more, can be further 20% by mass or more, can be further 25% by mass or more, can be further 30% by mass or more. The upper limit of this proportion is not limited, and it can be further 90% by mass or less, can be further 80% by mass or less, can be further 75% by mass or less, can be further 70% by mass or less, can be further 65% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 10 - 80% by mass, can be further 15 - 75% by mass, can be further 20 - 75% by mass, can be further 20 - 70% by mass, can be further 25 - 70% by mass, can be further 25 - 65% by mass. In each of the above ranges, as the range narrows, the needle holding performance (needle holding time) tends to improve.

[0064] (6) Composition of the thermoplastic elastomer composition As described above, the thermoplastic elastomer composition of the present invention contains a styrenic polymer (A), a softening agent (B), and an olefinic polymer (C). Among them, the styrenic polymer (A) is as described above.

[0065] The content ratio of the styrenic polymer (A) contained in the thermoplastic elastomer composition is not limited. For example, it can be 20 - 50% by mass. Within this range, a thermoplastic elastomer composition capable of forming a suppository can be obtained, and the suppository has excellent effects of suppressing liquid leakage from containers with a large amount of residual liquid and suppressing liquid leakage when the inserted needle is pulled out after being inserted for a long time. The content ratio of the styrenic polymer (A) can be further 23% by mass or more, can be further 25% by mass or more, can be further 30% by mass or more. On the other hand, the content ratio can be 48% by mass or less, can be further 45% by mass or less, can be further 40% by mass. The above upper and lower limits can be combinations of each other. For example, it can be 23 - 48% by mass, can be further 23 - 45% by mass, can be further 25 - 45% by mass, can be further 25 - 40% by mass, can be further 30 - 40% by mass.

[0066] There is no limitation on the total content ratio of the styrenic polymer (A), softening agent (B), and olefinic polymer (C) contained in the thermoplastic elastomer composition. For example, it can be 75 to 99% by mass. Within this range, a thermoplastic elastomer composition capable of forming a suppository can be obtained, and the suppository has excellent effects of suppressing liquid leakage from containers with a large amount of residual liquid and suppressing liquid leakage when the insertion needle is pulled out after being inserted for a long time. This total content ratio can further be 80% by mass or more, can further be 85% by mass or more, and can further be 90% by mass or more. On the other hand, this content ratio can be 98% by mass or less, can further be 97% by mass or less, and can further be 96% by mass or less. The above upper and lower limits can be combined with each other. For example, it can be 75 to 98% by mass, can further be 80 to 98% by mass, can further be 85 to 98% by mass, can further be 85 to 97% by mass, can further be 90 to 97% by mass, and can further be 90 to 96% by mass.

[0067] (6-1) Softening agent (B) The thermoplastic elastomer composition of the present invention contains a softening agent (B). By containing the softening agent (B), the thermoplastic elastomer composition of the present invention can be made soft, and the moldability and elongation at break can be improved. Thereby, the effect of suppressing liquid leakage can be obtained. The type of the softening agent (B) is not limited, and mineral oil-based softening agents, synthetic oil-based softening agents, etc. can be used. They can be used alone or in combination of two or more. Among them, as the mineral oil-based softening agent, examples include: paraffin-based oil (such as paraffin process oil), naphthenic-based oil (such as naphthenic process oil), liquid paraffin, mineral oil, white oil, etc. They can be used alone or in combination of two or more.

[0068] On the other hand, as the synthetic oil-based softening agent, examples include: hydrocarbon-based softening agents such as α-olefin oligomers, polybutene, alkylbenzenes, and naphthenes; ester-based softening agents such as diesters, polyol esters, and phosphates; ether-based softening agents such as polyethylene glycols and phenyl ethers; silicone-based softening agents such as dimethyl polysiloxanes and silicate esters; fluorine-based softening agents such as trifluoroethylene, etc. They can be used alone or in combination of two or more. Among them, in the present invention, from the viewpoint of affinity with the styrenic polymer (A), paraffin-based oil, naphthenic-based oil, and their mixtures are preferred, and paraffin-based oil is particularly preferred.

[0069] The kinematic viscosity of the softening agent (B) is not limited, but from the viewpoint of suppressing volatilization or exudation under heating conditions during manufacturing or use, etc., it is preferably 10 mm 2 / s or more, more preferably 50 mm 2 / s or more, more preferably 100 mm 2 / s or more. On the other hand, from the viewpoint of operability, 800 mm 2 / s or less, more preferably 600 mm 2 / s or less, more preferably 500 mm 2 / s or less. In addition, the kinematic viscosity is the value at 40 °C based on JIS Z8803.

[0070] There is no limitation on the Mw of the softening agent (B), which can be 500 to 3000, and can further be 800 to 1500. Within this range, it is easy to obtain a thermoplastic elastomer composition that is soft, has little needle penetration resistance, and has excellent needle holding performance (needle holding time). It should be noted that the Mw (weight average molecular weight) of the softening agent (B) can be measured by gel permeation chromatography. Its application can be as follows. · GPC device (Tosoh Corporation, model "Auto Sampler AS-8010") · Pump (manufactured by JASCO Corporation, model "PU-980") · Column oven (manufactured by Showa Denko K.K., model "AO-50") · Chromatographic column (manufactured by Showa Denko K.K., model "K-801 (8.0 × 300 mm)" 1 piece and model "K-802 (8.0 × 300 mm)" 1 piece used in series) · RI (differential refractometer) detector (manufactured by Hitachi, Ltd., model "L-3300") · Guard column: K-G (4.6 × 10 mm) · Column temperature: 40 °C · Eluent: chloroform · Eluent flow rate: 1.0 ml / minute · Sample concentration: about 3 mg / ml · Sample solution filtration: disposable filter with a pore size of 0.45 μm made of polytetrafluoroethylene · Standard for calibration curve: polystyrene (manufactured by Showa Denko K.K., product name "Shodex STANDARD": S-3.3, S-2.5, S-1.7)

[0071] The content of the softening agent (B) is not limited. For example, when the total amount of the styrene-based polymer (A) is 100 parts by mass, it can be 1 to 500 parts by mass, but in the present invention, it is 80 to 300 parts by mass. Within this range, the needle punching resistance is small and excellent needle holding performance (needle holding time) can be obtained, so it is preferred. The lower limit of the content of the softening agent (B) can be 90 parts by mass or more, can be further 100 parts by mass or more, and can be further 120 parts by mass or more. On the other hand, the upper limit can be 280 parts by mass or less, can be further 250 parts by mass or less, can be further 220 parts by mass or less, and can be further 200 parts by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 90 to 250 parts by mass, can be further 90 to 220 parts by mass, can be 100 to 220 parts by mass, and can be 100 to 200 parts by mass.

[0072] (6-2) Olefin polymer (C) The thermoplastic elastomer composition of the present invention contains an olefin polymer (C). By containing the olefin polymer (C), appropriate moldability (shapability) and mechanical strength can be imparted to the thermoplastic elastomer composition of the present invention. The olefin polymer (C) is a polymer having structural units derived from olefins as main structural units. Therefore, it includes homopolymers of one kind of olefin, copolymers of two or more kinds of olefins, copolymers of olefins and monomers other than olefins, etc. The content ratio of the structural units derived from olefins in the olefin polymer (C) is not limited. For example, 50% or more of all the structural units can be derived from olefins. This ratio can be further 60% or more, can be further 70% or more, can be further 80% or more, and can be further 90% or more. On the other hand, the upper limit is not limited and can be 100% or can be 100% or less. It should be noted that as monomers other than olefins, the following can be cited: acrylic acid, methacrylic acid, maleic acid, acrylate, methacrylate, vinyl acetate, etc. They can be used alone or in combination of two or more.

[0073] The kind of olefin as the monomer constituting the olefin polymer (C) is not limited, and the following can be cited: ethylene, propylene, 1-butene, 1-hexene, 1-octene, etc. They can be used alone or in combination of two or more. That is, as the olefin polymer (C), polyethylene, polypropylene, polybutene, etc. are included. These polymers can be used alone or in combination of two or more. That is, the olefin polymer (C) can be a mixture of the above polymers. For the thermoplastic elastomer composition of the present invention, among them, from the viewpoint of affinity with the styrene-based polymer (A) that can be used in the present invention, the olefin polymer (C) is preferably polypropylene, and particularly preferably a homopolymer of propylene.

[0074] Among the above, examples of the polyethylene include ethylene homopolymers and copolymers of ethylene and other olefins. Examples of the copolymers of ethylene and other olefins include ethylene-1-butene copolymers, ethylene-1-octene copolymers, etc. These copolymers can be random copolymers or block copolymers. It should be noted that the copolymers of ethylene and other olefins are polymers in which more than 50% of the total number of structural units are structural units derived from ethylene.

[0075] Among the above, examples of the polypropylene include propylene homopolymers and copolymers of propylene and other olefins. Examples of the copolymers of propylene and other olefins include propylene-ethylene copolymers, propylene-1-butene copolymers, etc. These copolymers can be random copolymers or block copolymers. It should be noted that the copolymers of propylene and other olefins are polymers in which more than 50% of the total number of structural units are structural units derived from propylene.

[0076] The MFR (melt flow rate) of the olefin-based polymer (C) is not limited and can be 0.5 to 30 g / 10 minutes, and can further be 1 to 15 g / 10 minutes. Within this range, a thermoplastic elastomer composition having excellent moldability can be easily obtained. It should be noted that this MFR is the value at 230°C and a load of 21.2 N based on ASTM D1238.

[0077] Furthermore, the flexural modulus of the olefin-based polymer (C) is not limited. From the viewpoints of the liquid leakage prevention property and the needle holding property of the obtained molded body, it is 1000 MPa or more, preferably 1100 MPa or more, and more preferably 1200 MPa or more. In addition, from the viewpoint of the liquid leakage prevention property of the obtained molded body, it is preferably 3000 MPa or less, more preferably 2500 MPa or less, and further preferably 2000 MPa or less. From these viewpoints, the flexural modulus of the olefin-based polymer (C) is 1000 to 3000 MPa, preferably 1100 to 2500 MPa, and more preferably 1200 to 2000 MPa. It should be noted that this flexural modulus can be measured according to JIS K6921-2 (test piece: 80 mm × 10 mm × 4 mm, test speed: 2 mm / minute).

[0078] The content of the olefin-based polymer (C) is not limited. For example, when the total amount of the styrene-based polymer (A) is set to 100 parts by mass, it can be 1 to 100 parts by mass, and in the present invention, it is 1 to 50 parts by mass. Within this range, excellent moldability and mechanical strength can be achieved, and thus it is preferred. The lower limit of the content of the olefin-based polymer (C) can be 2 parts by mass or more, can further be 5 parts by mass or more, can further be 7 parts by mass or more, can further be 10 parts by mass or more, can further be 12 parts by mass or more. On the other hand, the upper limit can be 45 parts by mass or less, can further be 40 parts by mass or less, can further be 35 parts by mass or less, can further be 25 parts by mass or less, can further be 19 parts by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 2 to 45 parts by mass, can further be 5 to 45 parts by mass, can further be 5 to 40 parts by mass, can further be 10 to 40 parts by mass, can further be 10 to 35 parts by mass.

[0079] (6-3) Other components In addition to the above-mentioned styrene-based polymer (A), softening agent (B), and olefin-based polymer (C), the thermoplastic elastomer composition of the present invention may further contain other components. Examples of other components include: fillers, other thermoplastic polymers other than the styrene-based polymer (A) and the olefin-based polymer (C), colorants, pigments, antistatic agents, antibacterial agents, antifungal materials, flame retardants, flame retardant aids, antioxidants, heat stabilizers, anti-aging agents, light stabilizers, ultraviolet absorbers, antifogging agents, anti-caking agents, dispersants, lubricants, and various other additives. They can be used alone or in combination arbitrarily. They can be used alone or two or more of them can be used in combination.

[0080] The total content ratio of the styrene-based polymer (A), softening agent (B), and olefin-based polymer (C) contained in the thermoplastic elastomer composition of the present invention is 75 to 99% by mass. Therefore, the content ratio of other components is 1 to 25% by mass. The content ratio of other components can be 2% by mass or more, can further be 3% by mass or more, can further be 4% by mass or more. On the other hand, the content ratio of other components can be 20% by mass or less, can further be 15% by mass or less, can further be 10% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 2 to 25% by mass, can further be 2 to 20% by mass, can further be 2 to 15% by mass, can further be 3 to 15% by mass, can further be 3 to 10% by mass, can further be 4 to 10% by mass.

[0081] (6-3-1) Filler (D) Among the above other components, examples of the filler (D) include: inorganic fillers and organic fillers. They can be used alone or two or more of them can be used in combination. Examples of the inorganic filler include talc, clay, wollastonite, silica, zeolite, hydrotalcite, silica stone, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, glass, alumina, magnesia, calcium carbonate (such as light calcium carbonate and heavy calcium carbonate), zinc carbonate, antimony trioxide, potassium titanate, boron nitride, metal fiber, metal whisker, ceramic whisker, carbon black, graphite, carbon fiber, etc. They may be used alone or in combination of two or more. Examples of the organic filler include starch, cellulose, wood powder, okara, bran, resin fiber, etc. They may be used alone or in combination of two or more.

[0082] Among the above, in the thermoplastic elastomer composition of the present invention, an inorganic filler is preferred, talc or calcium carbonate is more preferred, and talc is further preferred. In addition, the particle size and particle size distribution of the filler (D) are not limited. For example, the D50 (median particle size) of the filler (D) measured by the wet method may be 0.05 to 50 μm, further 0.1 to 40 μm, further 0.5 to 30 μm, and further 1.0 to 20 μm.

[0083] It should be noted that the D50 is measured for the particle size distribution using a laser diffraction / scattering particle size distribution measuring device, and is measured as the particle size of 50% of the cumulative volume from the small particle size side. As the wet laser diffraction / scattering particle size distribution measuring device, for example, the model "SALD-200VER" manufactured by Shimadzu Corporation can be used.

[0084] When the filler (D) is contained, its content is not limited. For example, when the total amount of the styrene-based polymer (A) is 100 parts by mass, the filler (D) may be 0.5 to 100 parts by mass. Within this range, there is a tendency to improve the liquid leakage inhibition performance and the needle holding performance (needle holding time). The lower limit of the content of the filler (D) may be 1 part by mass or more, further 2 parts by mass or more, further 5 parts by mass or more, further 7 parts by mass or more, and further 10 parts by mass or more. On the other hand, the upper limit may be 80 parts by mass or less, further 70 parts by mass or less, further 60 parts by mass or less, and further 50 parts by mass or less. The above upper and lower limits may be combinations of each other. For example, it may be 1 to 80 parts by mass, further 2 to 80 parts by mass, further 2 to 70 parts by mass, further 5 to 70 parts by mass, further 5 to 60 parts by mass, further 7 to 60 parts by mass, further 7 to 50 parts by mass, and further 10 to 50 parts by mass.

[0085] (6-3-2) Other thermoplastic polymers Among the above other components, as other thermoplastic polymers, examples include: other styrene polymers (E) other than styrene-based polymer (A), other vinyl polymers other than olefin-based polymer (C), polyamide-based polymers, polyester-based polymers, acrylic polymers, methacrylic polymers, rosin-based resins, petroleum resins, and the like.

[0086] Among the above, as other styrene polymers (E), examples include: styrene polymers, α-methylstyrene polymers, styrene-α-methylstyrene copolymers, and the like. As other vinyl polymers, examples include: ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-acrylate copolymers, ethylene-methacrylate copolymers, and the like. As polyamide-based polymers, examples include: nylon 6, nylon 66, and the like. As polyester-based polymers, examples include: polyethylene terephthalate, polybutylene terephthalate, and the like. As rosin-based resins, examples include: rosin ester resins, and the like. As petroleum resins, examples include: C5-based petroleum resins, C9-based petroleum resins, and hydrogenated petroleum resins obtained by hydrogenating them, and the like. They can be used alone or in combination of two or more.

[0087] Among the above, other styrene polymers (E) may also be contained. Further, as other styrene polymers (E), α-methylstyrene polymers and / or styrene-α-methylstyrene copolymers are preferred. Among them, in the styrene-α-methylstyrene copolymer, the proportion of α-methylstyrene-based monomer units is not limited. Relative to 100% by mass of the whole styrene-α-methylstyrene copolymer, the proportion of α-methylstyrene-based monomer units is preferably 10% by mass or more, more preferably 20% by mass or more, further preferably 30% by mass or more, particularly preferably 40% by mass or more, and even more particularly preferably 50% by mass or more.

[0088] Further, from the viewpoint of moldability, other styrene polymers (E) are preferably lower in molecular weight than styrene-based polymer (A). Its molecular weight is not limited. For example, a styrene-based polymer having Mw of 1000 to 30000, Mn of 800 to 20000, and Mw greater than Mn can be used. By containing such other styrene polymers (E), the following effects are achieved: improving the moldability and elongation at break of the thermoplastic elastomer composition of the present invention, and improving the leakage suppression effect. It should be noted that these other styrene polymers can be referred to as tackifiers.

[0089] Regarding the above molecular weight ranges of other styrene polymers (E), Mw can further be 1200 to 25000, can further be 1500 to 20000, can further be 2000 to 15000. Additionally, Mn can further be 1000 to 8000, can further be 1500 to 7000, can further be 2000 to 6000. It should be noted that the Mw (weight-average molecular weight) and Mn (number-average molecular weight) of other styrene polymers (E) can be measured using gel permeation chromatography. The operation is the same as that of polymer (A1).

[0090] In addition, the softening point of other styrene polymers (E) is not limited. For example, regarding the softening point based on ASTM E28, it can be 80 to 200 °C, can further be 90 to 180 °C, can further be 100 to 160 °C. By containing such other styrene polymers (E), the effect of improving the heat resistance of the thermoplastic elastomer composition of the present invention is achieved.

[0091] Examples of such other styrene polymers (E) include: the Kristalex (trade name) series manufactured by Eastman Chemical Company, the Endex (trade name) series manufactured by Eastman Chemical Company, the FTR (trade name) series manufactured by Mitsui Chemicals, Inc., the FMR (trade name) series manufactured by Mitsui Chemicals, Inc., theレジット(trade name) manufactured by Sanyo Chemical Industries, Ltd., the Arufon (trade name) manufactured by Toagosei Co., Ltd., etc.

[0092] Specifically, examples include: the product named "Kris talex5140", the product named "Kristalex 3085", the product named "Kris talex 3100", the product named "Kris talex 1120", the product named "Endex155" manufactured by Eastman Chemical Company, the product named "FTR2140", the product named "FMR0150" manufactured by Mitsui Chemicals, Inc., etc. They can be used alone or in combination of two or more.

[0093] When other styrenic polymers (E) are contained, the content of the other styrenic polymers (E) is not limited. For example, when the total amount of the styrenic polymer (A) is 100 parts by mass, it can be 0.1 to 50 parts by mass. Within this range, the liquid leakage suppression effect and the needle holding property can be improved. The lower limit of the content of the other styrenic polymers (E) can be 0.5 parts by mass or more, can further be 1.0 parts by mass or more, can further be 1.5 parts by mass or more, and can further be 2.0 parts by mass or more. On the other hand, the upper limit can be 45 parts by mass or less, can further be 35 parts by mass or less, can further be 25 parts by mass or less, and can further be 15 parts by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 0.5 to 45 parts by mass, can further be 1.0 to 35 parts by mass, can be 1.5 to 25 parts by mass, and can be 2.0 to 15 parts by mass.

[0094] (7) Others regarding the thermoplastic elastomer composition The properties and performance of the thermoplastic elastomer composition of the present invention are not limited. From the viewpoint of suppressing the needle penetration resistance, the A hardness of the thermoplastic elastomer composition is preferably 60 or less. On the other hand, from the viewpoint of obtaining high needle holding performance, the A hardness of the thermoplastic elastomer composition is preferably 10 or more. This value can further be 10 to 50, can further be 11 to 40, can further be 12 to 38, can further be 13 to 36, and can further be 14 to 34. This A hardness is a value measured according to the measurement method in the examples described later.

[0095] In addition, the thermoplastic elastomer composition of the present invention can obtain thermoplasticity, that is, a thermally reversible molded body obtained by heating and cooling, and general molding methods such as injection molding, extrusion molding, and compression molding can be used. MFR is an index of formability. From the viewpoints of formability and mechanical strength, the MFR of the thermoplastic elastomer composition of the present invention can be 0.1 to 150 g / 10 minutes, can be 0.2 to 135 g / 10 minutes, can be 0.5 to 110 g / 10 minutes, can be 1.0 to 90 g / 10 minutes, and can be 2.0 to 75 g / 10 minutes. This MFR is a value measured according to the measurement method in the examples described later.

[0096] Furthermore, from the viewpoint of the liquid leakage suppression effect, the tensile strength of the thermoplastic elastomer composition of the present invention can be 1.0 to 15 MPa, can be 1.2 to 12 MPa, can be 1.5 to 7.0 MPa, can be 2.0 to 6.0 MPa, and can be 2.5 to 5.5 MPa. This tensile strength is a value measured according to the measurement method in the examples described later.

[0097] In addition, from the viewpoint of suppressing liquid leakage, the elongation at break of the thermoplastic elastomer composition of the present invention can be 500 to 1500%, can be 550 to 1300%, can be 600 to 1100%, can be 650 to 1000%, can be 700 to 930%. This elongation at break is a value measured according to the measurement method of the examples described below.

[0098] Furthermore, from the viewpoint of suppressing liquid leakage, the tear strength of the thermoplastic elastomer composition of the present invention can be 5.0 to 30 MPa, can be 5.5 to 20 MPa, can be 6.0 to 17 MPa, can be 6.5 to 15 MPa, can be 7.0 to 12.5 MPa. This tear strength is a value measured according to the measurement method of the examples described below.

[0099] The thermoplastic elastomer composition of the present invention can be manufactured by any method, and its processes and the like are not limited. For example, it can be manufactured by mixing a styrene-based polymer (A), a softening agent (B), an olefin-based polymer (C), and other optional components as needed using various heated kneading machines such as a single-screw extruder, a twin-screw extruder, a roll, a Banbury mixer, a Brabender mixer, and a kneader.

[0100] The thermoplastic elastomer composition of the present invention can be used for any purpose, but can be widely used for various medical products. That is, for example, it is suitable for the plug body of a medical container (medical container plug body), various connecting tubes such as an infusion set, a liquid medicine container, a mixed injection plug for hemodialysis, and a sealing member for a medical vial or a blood collection tube. Examples

[0101] Hereinafter, the present invention will be described in more detail based on examples, but these examples are merely examples shown for convenience of explanation, and the present invention is not limited to these examples in any sense.

[0102] [1] Preparation of thermoplastic elastomer composition Each raw material component was weighed out in accordance with the composition ratios (mass ratios) shown in Tables 1 to 3, and then the weighed-out raw material components were premixed to obtain a mixture. At this time, an antioxidant (phenolic antioxidant, manufactured by BASF Corporation, product name "Irganox 1010") was premixed at a ratio of 0.3 parts by mass with respect to 100 parts by mass of the styrene-based polymer (A). The premixing was carried out using a stirrer. Then, the obtained mixture was melt-kneaded to obtain the thermoplastic elastomer compositions of Examples 1 to 22 and Comparative Examples 1 to 8. This melt-kneading was carried out using a twin-screw extruder (continuous kneading machine) under the following conditions. ·Twin-screw extruder: manufactured by Technovel Corporation, model "KZW32TW-60MG-NH" ·Barrel temperature: 180 - 240 °C ·Screw rotation speed: 300 revolutions per minute

[0103] [Table 1]

[0104] [Table 2]

[0105] [Table 3]

[0106] The components of each raw material are as follows. (1) Styrene-based polymer (A) (1-1) Polymer (A1) SEBS (manufactured by Kraton Polymers, product name "G1641", X1-Y1-X1 type triblock hydrogenated copolymer (X1 forms two molecular ends), content ratio of styrene-based monomer units: 32% by mass, Mw: 240,000, Mn: 220,000, Mw / Mn: 1.09, ratio of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y1): 67% by mass)

[0107] (1-2) Polymer (A2) SEBS (manufactured by Kraton Polymers, product name "A1535", X2-Y2-X2-Y2-X2 type multiblock hydrogenated copolymer (with 3 X2s and 2 Y2s, X2 forms two molecular ends), content ratio of styrene-based monomer units: 58% by mass, Mw: 270,000, Mn: 250,000, Mw / Mn: 1.08, ratio of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y2): 30% by mass)

[0108] (1-3) Polymer (A3) SEBS (manufactured by Kraton Polymers, product name "G1651H", X1-Y1-X1 type triblock hydrogenated copolymer (with 2 X3s, X3 forms two molecular ends), content ratio of styrene-based monomer units: 33% by mass, Mw: 290,000, Mn: 260,000, Mw / Mn: 1.12, ratio of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y3): 37% by mass)

[0109] (2) Plasticizer (B) Paraffin oil (manufactured by Idemitsu Kosan Co., Ltd., product name "PW380", kinematic viscosity at 40 °C measured based on JIS Z8803 is 380 mm 2 / s), Mw: 1100.

[0110] (3) Olefin-based polymer (C) Polyolefin resin (propylene homopolymer, manufactured by Sun Allomer Co., Ltd., product name "PX600N", MFR at 230 °C and 21.2 N load based on ASTM D1238: 7.5 g / 10 min, flexural modulus: 1650 MPa)

[0111] (4) Filler (D) Talc filler (talc, manufactured by Hayashi Kasei Co., Ltd., product name "TP-TK", D50: 11 μm)

[0112] (5) Other styrene-based polymer (E) Tackifier (α-methylstyrene-styrene copolymer, manufactured by Eastman Chemical Company, product name "Kris talex5140", Mw: 4900, Mn: 4100, softening point measured based on ASTM E28: 140 °C)

[0113] [2] Preparation of molded articles for evaluation (1) The pellets composed of the thermoplastic elastomer compositions of Examples 1 to 22 and Comparative Examples 1 to 8 obtained in [1] above were molded (injection molding) under the injection conditions shown in (3) below to obtain a sheet-shaped molded article (injection molded article) with a length of 125 mm × width of 125 mm × thickness of 2 mm. Test pieces cut from this sheet-shaped molded article were used to measure the A hardness, tensile strength, elongation at break, and tear strength. These measurements are described later.

[0114] (2) The pellets composed of the thermoplastic elastomer compositions of Examples 1 to 22 and Comparative Examples 1 to 8 obtained in [1] above were molded (injection molding) under the injection conditions shown in (3) below to obtain a columnar molded article (injection molded article) with a length of 125 mm × width of 25 mm × thickness of 6 mm. A substantially cylindrical molded body with a diameter of 20 mm × height of 6 mm was blanked out from this columnar molded article and molded. This substantially cylindrical molded body was used as a plug body for the evaluation described later. These evaluations are described later.

[0115] (3) Molding conditions Injection molding machine: manufactured by Mitsubishi Heavy Industries, Ltd., model "100MSIII-10E" Injection molding temperature: 200 °C Injection pressure: 30% Injection time: 10 seconds Mold temperature: 40 °C

[0116] [3] Various measurements (1) MFR The MFR of the pellets composed of the thermoplastic elastomer compositions (Examples 1 to 22 and Comparative Examples 1 to 8) obtained in the above [1] was measured under the conditions of a temperature of 230°C and a nominal load of 21.2 N in accordance with ASTM D1238. In addition, in this measurement, a testing machine (product name “Melt Flow Indexer G-02”) manufactured by Toyo Seiki Seisaku-sho, Ltd. was used. The results are shown in Tables 1 to 3. “NF” in the tables means non-flowing, indicating significantly poor moldability.

[0117] (2) A hardness The sheet-shaped molded article (thickness 2 mm) obtained in the above [2](1) was conditioned for 1 day at a temperature of 23°C and a humidity of 50%, and then three conditioned sheet-shaped molded articles were overlapped (total 6 mm) to form a laminate. On this basis, the A hardness of the laminate (Examples 1 to 22 and Comparative Examples 1 to 8) was measured. Specifically, in accordance with JIS K6253, the A hardness at a measurement time of 1 second (the value 1 second after the start of the test) was measured. The results are shown in Tables 1 to 3.

[0118] (3) Tensile strength The sheet-shaped molded article (thickness 2 mm) obtained in the above [2](1) was conditioned for 1 day at a temperature of 23°C and a humidity of 50%, and then a No. 3 dumbbell-shaped test piece was punched out from the conditioned sheet-shaped molded article. Using the obtained No. 3 dumbbell-shaped test piece, the tensile strength was measured in accordance with JIS K6251 (Examples 1 to 22 and Comparative Examples 1 to 8). Specifically, using a tensile testing machine (manufactured by Shimadzu Corporation, model “Auto graph AG-50kND”), at a temperature of 23°C and a tensile speed of 500 mm / minute, the maximum tensile force recorded when the test piece was stretched until it broke was measured. Then, the value obtained by dividing the maximum tensile force by the initial cross-sectional area of the test piece was calculated as the tensile strength. The results are shown in Tables 1 to 3.

[0119] (4) Elongation at break The sheet-shaped molded article (thickness: 2 mm) obtained in [2](1) above was conditioned at a temperature of 23°C and a humidity of 50% for 1 day, and then a No. 3 dumbbell-shaped test piece was punched out from the conditioned sheet-shaped molded article. Using the obtained No. 3 dumbbell-shaped test piece, the tensile strength was measured in accordance with JIS K6251 (Examples 1 to 22 and Comparative Examples 1 to 8). Specifically, using a tensile testing machine (manufactured by Shimadzu Corporation, model "Auto graph AG-50kND"), the test piece was stretched under the conditions of a temperature of 23°C and a stretching speed of 500 mm / minute, and the elongation at break (overall length in the elongated state) was measured. Then, the ratio (%) of the "elongation" at break to the "initial length" was calculated as the elongation at break. The results are shown in Tables 1 to 3.

[0120] (5) Tear strength The sheet-shaped molded article (thickness: 2 mm) obtained in [2](1) above was conditioned at a temperature of 23°C and a humidity of 50% for 1 day, and then a "non-notch angular test piece" was punched out from the conditioned sheet-shaped molded article. Using the obtained non-notch angular test piece, the tensile strength was measured in accordance with JIS K6252 (Examples 1 to 22 and Comparative Examples 1 to 8). Specifically, using a tensile testing machine (manufactured by Shimadzu Corporation, model "Auto graph AG-50kND"), the test piece was stretched under the conditions of a temperature of 23°C and a stretching speed of 500 mm / minute, and the maximum tensile force recorded until the test piece broke was measured. Then, the value obtained by dividing the maximum tensile force by the initial cross-sectional area of the test piece was calculated as the tear strength. The results are shown in Tables 1 to 3.

[0121] [4] Preparation of suppository and evaluation of suppository body (1) Preparation of suppository Each suppository body (substantially cylindrical molded body with a diameter of 20 mm × a height of 6 mm) composed of the thermoplastic elastomer compositions of Examples 1 to 22 and Comparative Examples 1 to 8 obtained in [2](2) above was inserted into the lower end of the inner hole of a tubular polypropylene cap with an inner diameter of 20 mm / outer diameter of 21 mm × a height of 10 mm (the non-contact liquid surface side of the suppository), and the suppository body and the cap were integrated. Then, polypropylene was inserted and molded from the upper end (the contact liquid surface side of the suppository) of the integrated product of the polypropylene cap and the suppository body, and a polypropylene flange portion was formed on the upper end side of the integrated product, thereby obtaining a suppository (Examples 1 to 22 and Comparative Examples 1 to 8).

[0122] (2) Preparation of soft bag for infusion 500 ml of water was injected into a soft bag that was to be an infusion bag with an internal volume of 700 ml, and then the injection port of the soft bag was sealed with a suppository to obtain a test soft bag for infusion.

[0123] (3) Measurement of liquid leakage rate Suspend the flexible bag for infusion obtained in the above [4](2) from the bracket with the medicine plug facing downwards. Next, insert a medical plastic needle (manufactured by Nipro Corporation, model "ISA-600A00Z") from the lower side through the center of the plug body exposed on the non-contact liquid level side of the medicine plug. At this time, the medical plastic needle is inserted perpendicular to the exposed surface of the plug body and inserted until the root of the medical plastic needle contacts the exposed surface of the plug body. In addition, during the test, in order not to cause liquid leakage from the medical plastic needle, the liquid flow path of the medical plastic needle is sealed for use.

[0124] After standing for 24 hours after the above insertion, then pull out the medical plastic needle from the plug body and wipe the water droplets on the exposed surface of the plug body. Then, after 1 minute, evaluate the liquid leakage (water leakage) from the needle hole formed in the plug body. That is, after 1 minute, judge the "state of liquid dripping from the needle hole after 1 minute", "state where no liquid dripping is observed from the time of needle pulling out to 1 minute, but water droplets adhere to the needle hole", and "state where liquid dripping occurs during the period from the time of needle pulling out to 1 minute before, but the liquid dripping stops after 1 minute" as liquid leakage. This evaluation is carried out for each 10 of Examples 1 to 22 and Comparative Examples 1 to 8, and the proportion (%) of the number of cases where liquid leakage is confirmed is calculated. The results are shown in Tables 1 to 3. That is, set the liquid leakage rate of the case where liquid leakage occurs in all 10 tests as 100%, and set the liquid leakage rate of the case where no liquid leakage is found in the 10 tests as 0%. It should be noted that the test is carried out in a room at a temperature of 23°C and a humidity of 50%.

[0125] (4) Liquid leakage property (score evaluation) Regarding the test specimens where liquid leakage was confirmed in the above [4](3), determine which of the following four criteria [A] to [D] the liquid leakage state corresponds to, and fill in each criterion accordingly. Set the score corresponding to case [A] as "1 point", the score corresponding to case [B] as "3 points", the score corresponding to case [C] as "3 points", and the score corresponding to case [D] as "6 points", and calculate the total score of 10 test specimens. The results are shown in Tables 1 to 3.

[0126] [A]: "State where no liquid dripping is observed from the time of needle pulling out to 1 minute, and no water droplets are observed on the needle hole after 1 minute" [B]: "State where no liquid dripping is observed from the time of needle pulling out to 1 minute, but water droplets adhere to the needle hole" [C]: "State where liquid dripping occurs during the period from the time of needle pulling out to 1 minute before, but the liquid dripping stops after 1 minute" [D]: "State of dripping from the pinhole after 1 minute"

[0127] (5) Needle holding time Suspend the flexible infusion bag obtained in [4](2) above from the bracket with the medicine plug facing downward. Next, at the center of the plug body exposed from the non-contact liquid level side of the medicine plug, insert a medical metal needle (manufactured by Nipro Corporation, model "TC-00501K") from the lower side of the plug body. At this time, the medical metal needle is inserted perpendicular to the exposed surface of the plug body and is inserted to a position where the root of the medical metal needle contacts the exposed surface of the plug body. In addition, the medicine plugs of each flexible infusion bag are arranged such that the exposed surface of the plug body is parallel to the horizontal plane of the test stand. Furthermore, a 500 g weight is installed on the medical metal needle, and this weight is arranged to hang vertically downward perpendicular to the exposed surface of the plug body. In addition, during the test, in order not to cause liquid leakage from the medical metal needle, the liquid flow path of the medical metal needle is sealed and used. It should be noted that the test is carried out in a room at a temperature of 23 °C and a humidity of 50%. Then, measure the time from the above insertion until the medical metal needle falls off, and measure it as the needle holding time (unit: "seconds"). The results are shown in Tables 1 to 3.

[0128] [5] Effects of the examples Taking the total content (mass%) of polymer (A1) and polymer (A2) when styrene-based polymer (A) is 100 mass% as composition condition 1, composition condition 1 of the thermoplastic elastomer composition of the present invention is greater than 50 mass%. Taking the content (mass%) of polymer (A1) when the total amount of polymer (A1) and polymer (A2) is 100 mass% as composition condition 2, composition condition 2 of the thermoplastic elastomer composition of the present invention is 5 to 90 mass%. Taking the content (mass%) of polymer (A3) when the total amount of polymer (A2) and polymer (A3) is 100 mass% as composition condition 3, composition condition 3 of the thermoplastic elastomer composition of the present invention is 10 to 80 mass%.

[0129] Examples 1 to 4 use two kinds of polymer (A1) and polymer (A2). Compared with Comparative Example 1 using only polymer (A1), it can be seen that the liquid leakage inhibition effect (low liquid leakage rate and liquid leakage fraction value) and needle holding performance of Examples 1 to 4 are excellent. From Comparative Example 2, it can be seen that when only polymer (A2) is used, the affinity with the softening agent or olefin resin is insufficient and the test sample cannot be obtained. It is known that the MFR of Comparative Example 5, in which the softening agent component of Example 3 was reduced to 50 parts by mass, was "NF", that is, the moldability was insufficient at high viscosity, and the liquid leakage rate also reached 100%.

[0130] Examples 5 and 6 are cases where polymer (A3) was added to Example 3 and the composition conditions 1 were 80% by mass and 70% by mass, respectively. It can be seen that the liquid leakage suppression effect is good and the needle holding performance is further improved. Comparative Example 3 is a case where polymer (A3) was used in a large amount and the composition condition 1 was 20% by mass. It can be seen that the liquid leakage suppression effect and the needle holding performance are reduced. Example 7 is a case where the usage amounts of polymer (A1), polymer (A2), and polymer (A3) were changed respectively, but the composition conditions 1, 2, and 3 were satisfied. It can be seen that it has the same liquid leakage suppression effect and needle holding performance as Examples 5 and 6 of the present invention. On the other hand, in Comparative Example 4, although the composition conditions 1 and 2 were satisfied, the composition condition 3 was 83% by mass, and the liquid leakage rate also reached 90%.

[0131] Examples 8 and 10 are cases where a filler was added to Example 3. It can be seen that the liquid leakage suppression effect and the needle holding property are improved according to the usage amount of the filler. In addition, it was also confirmed that the same filler usage effect was obtained in Examples 9, 11, 12, and 13 in which a filler was added to Examples 2, 4, 5, and 6. On the other hand, it can be seen that the composition conditions 1 of Comparative Examples 7 and 8 in which polymer (A3) was used in a large amount compared with Examples 12 and 13 were 50% by mass or less, so the liquid leakage suppression effect was reduced. Examples 14 to 18 are cases where the usage amounts were changed within the range of satisfying the composition conditions 1, 2, and 3 of polymer (A1), polymer (A2), and polymer (A3). It can be seen that both the liquid leakage suppression effect and the needle holding performance are excellent.

[0132] Examples 19 and 20 are cases where other styrene-based polymers (E) were added to Example 10. It can be seen that the needle holding performance is further improved. In addition, it can be seen that compositions with good liquid leakage suppression effect and needle holding performance were also obtained in Examples 21 and 22 using polymer (A3). From the above results, it can be seen that the liquid leakage suppression effect and the needle holding performance of the thermoplastic elastomer composition of the present invention are excellent, and it is particularly applicable to the plug body of a medicine plug of a medical container involving a puncture operation, etc. Industrial Applicability

[0133] The thermoplastic elastomer composition of the present invention can be used for any purpose, but can be widely used for various medical products. That is, for example, it is applicable to the plug body of a medicine plug of a medical container, various connecting tubes such as an infusion set, etc.

Claims

1. A thermoplastic elastomer composition comprising a styrenic polymer (A), a softening agent (B), and an olefinic polymer (C), characterized in that, The styrenic polymer (A) comprises a polymer (A1) and a polymer (A2). The polymer (A1) is a block copolymer having a styrenic polymer block (X1) and a conjugated diene compound polymer block (Y1). The styrenic polymer block (X1) forms at least one molecular end of the polymer (A1), and the proportion of structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y1) is 50% by mass or more. The polymer (A2) is a block copolymer having two or more styrenic polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2). The styrenic polymer block (X2) forms at least one molecular end of the polymer (A2), and the proportion of structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y2) is less than 50% by mass. When the styrenic polymer (A) is 100 parts by mass, the softening agent (B) is 80 to 300 parts by mass, and the olefinic polymer (C) is 1 to 50 parts by mass. When the styrenic polymer (A) is 100% by mass, the total of the polymer (A1) and the polymer (A2) exceeds 50% by mass.

2. The thermoplastic elastomer composition according to claim 1, wherein, When the total of the polymer (A1) and the polymer (A2) is 100% by mass, the polymer (A1) is 5 to 90% by mass.

3. The thermoplastic elastomer composition according to claim 1 or 2, wherein, The styrenic polymer (A) further comprises a polymer (A3). The polymer (A3) is a block copolymer having a styrenic polymer block (X3) and a conjugated diene compound polymer block (Y3). The number of styrenic polymer blocks (X3) is two or less, and the proportion of structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y3) is less than 50% by mass.

4. The thermoplastic elastomer composition according to claim 3, wherein, When the total of the polymer (A2) and the polymer (A3) is 100% by mass, the polymer (A3) is 10 to 80% by mass.

5. The thermoplastic elastomer composition according to claim 1 or 2, further comprising a filler (D), and when the styrenic polymer (A) is 100 parts by mass, the filler (D) is 0.5 to 100 parts by mass.

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