Thermoplastic elastomer composition and thermoplastic elastomer composition for plug body of medical container

Abstract

This thermoplastic elastomer composition contains a styrene polymer (A), a softening agent (B), and an olefin polymer (C), and is characterized in that: (A) contains a polymer (A1) having a styrene polymer block (X1) and a conjugated diene compound polymer block (Y1), the ratio of structural units derived from 1, 2-vinyl bonds in the (Y1) constituting the (A1) being 50 mass% or more; (A) is contained in an amount of 20-50% by mass relative to the entire composition, the total of (A), (B), and (C) is 75-99% by mass, and (A1) is greater than 20% by mass but 80% by mass or less when (A) is taken as 100% by mass.

Description

Technical Field

[0001] The present invention relates to a thermoplastic elastomer composition and a thermoplastic elastomer composition for a medical container plug. More specifically, the present invention relates to a thermoplastic elastomer composition containing a block copolymer and a thermoplastic elastomer composition for a medical container plug, the block copolymer having a styrene-based polymer block and a conjugated diene-based compound polymer block in which the proportion of structural units derived from 1,2-vinyl bonds is 50% by mass or more. Background Art

[0002] When it is necessary to take 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 suspended 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 thereof. In use, a metal or plastic insertion needle having a flow path is inserted through the elastomer to connect the inside and the 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 has used 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 materials 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 having improved liquid leakage resistance and resealability, a medical resin composition is disclosed, which contains: (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-decomposed 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 re-sealability, 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 softening agent.

[0006] In the above-mentioned Patent Document 3, as a medical rubber stopper having excellent needle puncture characteristics and good leakage tightness 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 softening agent, and (C) a polyolefin resin.

[0007] Among the various performances required for the suppository as described above, a performance of suppressing leakage of liquid from the through-hole formed in the elastomer after pulling out the insertion needle, that is, a liquid leakage suppressing effect, is required. 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. Furthermore, 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 suppository, since they are not designs assuming a large amount of residual liquid and are not designs 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 suppository having excellent liquid leakage suppressing effects for a container with a large amount of residual liquid and 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 softening agent (B), and an olefin-based polymer (C), characterized in that The styrenic polymer (A) contains a styrenic block copolymer having a styrenic polymer block (X1) and a conjugated diene compound polymer block (Y1), i.e., polymer (A1). The proportion of the structural unit derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y1) constituting the polymer (A1) is 50% by mass or more. When the total amount of the thermoplastic elastomer composition is 100% by mass, the styrenic polymer (A) is 20 to 50% by mass, and the total of the styrenic polymer (A), the softening agent (B), and the olefinic polymer (C) is 75 to 99% by mass. When the styrenic polymer (A) is 100% by mass, the polymer (A1) is more than 20% by mass and 80% by mass or less. [2] The thermoplastic elastomer composition according to [1] above further contains a filler (D) and / or a tackifier (E). [3] The thermoplastic elastomer composition according to [1] or [2] above, wherein the styrenic polymer (A) further contains a polymer (A2) as a styrenic block copolymer. The polymer (A2) has 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 the structural unit derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y2) is less than 50% by mass. [4] The thermoplastic elastomer composition according to any one of [1] to [3] above, wherein the styrenic polymer (A) further contains a polymer (A3) as a styrenic block copolymer. The polymer (A3) has 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 unit derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y3) is less than 50% by mass. [5] A thermoplastic elastomer composition for a medical container plug, characterized in that it is composed of the thermoplastic elastomer composition according to any one of [1] to [4] above. Advantages of the Invention

[0010] According to the thermoplastic elastomer composition of the present invention, a medicine plug excellent in the liquid leakage inhibition effect for a container with a large amount of residual liquid and the liquid leakage inhibition effect when the inserted needle is pulled out after being held for a long time without being pulled out can be obtained. Detailed Description

[0011] Hereinafter, the present invention will be described according to specific embodiments. However, the present invention is not limited to these embodiments. These embodiments are merely illustrative examples shown for the convenience of explanation, and the present invention is in no way limited thereto, 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 converted to 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 polymer (A1). The styrenic polymer (A) may contain no other polymers except the polymer (A1). As described later, as other polymers, for example, a polymer (A2) and / or a polymer (A3) may be included.

[0015] (2) Polymer (A1) The polymer (A1) is a block copolymer having a styrenic polymer block (X1) and a conjugated diene compound polymer block (Y1). From the viewpoint of having a styrenic polymer block (X1), the polymer (A1) may also be referred to as a styrenic polymer (A1). This polymer (A1) 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 (A1) is a hydrogenated product, the hydrogenation rate is not limited and may be 80% or more, may be 90% or more, and may be 100% or less. Since hydrogenation acts on the conjugated diene compound polymer block (Y1) in the polymer (A1), the hydrogenation rate is obtained by comparing the carbon-carbon double bond content ratio of the polymer (A1) before hydrogenation and the polymer (A1) after hydrogenation. In addition, the carbon-carbon double bond content ratio 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-mentioned hydrogenated polymer (A1) 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-mentioned hydrogenated polymer (A1) may also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrenic polymer, or a hydrogenated styrenic 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 suppression performance as compared with the case where it is not contained or contained in a smaller amount. The reason is not clear yet, but by containing the polymer (A1), as compared with the case where the polymer (A1) is not contained or contained in a smaller 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 properties contribute. In particular, the improvement of mechanical strengths such as tensile strength, elongation at break, and tear strength may contribute to the improvement of the liquid leakage suppression 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. Further, 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 unit of the polymer (A1) is not limited. When the whole polymer (A1) is set to 100% by mass, the content ratio of the styrene-based monomer unit 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 combinations of 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 unit 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 unit 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 ring from styrene and styrene derivatives. 1 That is, it can be calculated based on the signals of the hydrogen atoms of the benzene ring from styrene and styrene derivatives.

[0019] The Mw of the polymer (A1) is not limited and can be 50,000 to 500,000, further can be 70,000 to 400,000, and further can be 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 can be 60,000 to 400,000, and further can be 80,000 to 260,000. Moreover, the Mw / Mn of the polymer (A1) is not limited and can be 1.00 to 1.30, further can be 1.03 to 1.17, and further can be 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 easy to utilize heating operations in sterilization treatment etc., and thus is preferred.

[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 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 columns (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 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 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) can have polar functional groups such as carboxyl group, hydroxyl group, acid anhydride group, amino group, epoxy group, etc. in the molecular chain and / or at the molecular end as needed. They can be used alone or in combination of two or more.

[0022] (2-1) Styrenic polymer block (X1) The styrene-based polymer block (X1) is a polymer block having styrene-based monomer units as the main structural units. The styrene-based monomer units are structural units having styrene and / or styrene derivatives as monomers. Among them, as the 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.

[0023] In the styrene-based monomer units constituting the styrene-based polymer block (X1), the proportion of units derived from styrene (units not derived from styrene derivatives) is not limited, but relative to the whole styrene-based 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 styrene-based polymer block (X1) contains other structural units in addition to the styrene-based 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.

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

[0025] In addition, as the mode in which the polymer (A1) is a linear polymer and the styrene-based polymer block (X1) forms two molecular ends, for example, "X1-Y1-X1", "X1-Y1-X1-Y1-X1", "X1-Y1-X1-Y1-X1-Y1-X1", etc. can be cited. That is, various polymers in which non-hydrogenated products are collectively called SBS and hydrogenated products are collectively called SEBS can be cited. They can be used alone or in combination of two or more. In addition, when the polymer (A1) is a branched polymer, it can include the mode in which the styrene-based polymer block (X1) forms three or more molecular ends. That is, by forming at least one molecular end of the polymer (A1) with the styrene-based polymer block (X1), 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 convenience, each X1 represents a 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 can be the same or different. The same applies to each Y1. In addition, the styrene - based polymer block (X1) can 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 - based compound polymer block (Y1) The conjugated diene - based compound polymer block (Y1) is a polymer block mainly composed of conjugated diene - based compound monomer units. The conjugated diene - based compound monomer unit 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 - based compound monomer forming the conjugated diene - based compound polymer block (Y1), it contains at least a structural unit derived from 1,3 - butadiene. Furthermore, the conjugated diene - based compound polymer block (Y1) is preferably a polymer block mainly composed of 1,3 - butadiene monomer units.

[0028] The proportion of the conjugated diene - based compound monomer unit constituting the conjugated diene - based compound polymer block (Y1) is not limited. Relative to the whole of the conjugated diene - based compound polymer block (Y1), 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 generally can be 100% by mass or less. When the conjugated diene - based compound polymer block (Y1) contains other structural units in addition to the conjugated diene - based compound monomer unit, 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.

[0029] As described above, the conjugated diene compound polymer block (Y1) contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer units can be either 1,2-vinyl-bonded units [i.e., -CH2-CH(CH=CH2)-] or 1,4-vinyl-bonded units (including cis-1,4-bonds and trans-1,4-bonds) [i.e., -CH2-CH=CH-CH2-]. They can be used alone or in combination of two or more. However, in the present invention, the conjugated diene compound polymer block (Y1) is a block in which the proportion of the structural units derived from the 1,2-vinyl bond is 50% by mass or more. In addition, the structural units derived from the 1,4-vinyl bond and the structural units derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y1) may not be hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural units derived from the 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), when the total of the units derived from the 1,3-butadiene monomer is set to 100% by mass, only needs to be 50% by mass or more, preferably 52% by mass or more, more preferably 54% by mass or more, further preferably 56% by mass or more, and particularly preferably 58% by mass or more. Its upper limit is not limited and can be 100% by mass. For example, it can be 90% by mass or less, can be 85% by mass or less, and can be 80% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 52 to 100% by mass, can further be 54 to 90% by mass, can further be 56 to 85% by mass, and can further be 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.). 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 H-NMR analysis. Specifically, the block copolymer before hydrogenation is dissolved in CDCl3, and the 1 H-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.

[0032] (3) Polymer (A2) In addition to containing polymer (A1) as the styrene-based polymer (A), the thermoplastic elastomer composition of the present invention may also contain polymer (A2) as other polymers. Polymer (A2) is a block copolymer having two or more styrene-based polymer blocks (X2) and two or more conjugated diene-based 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) 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 polymer (A2) is a hydride, the hydrogenation rate is not limited, and it can be 80% or more, it can be 90% or more, and it can be 100% or less. Since hydrogenation acts on the conjugated diene-based compound polymer block (Y2) in polymer (A2), the hydrogenation rate is determined by comparing the content ratio of carbon-carbon double bonds in polymer (A2) before hydrogenation and polymer (A2) 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-mentioned hydrogenated polymer (A2) can also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrene-based polymer, or a hydrogenated styrene-based copolymer. 1 In the thermoplastic elastomer composition of the present invention, by containing polymer (A2), compared with the case where polymer (A2) is not contained, there is a tendency to improve the liquid leakage suppression performance and improve the needle holding performance (needle holding time). The reason is not clear yet, but by containing polymer (A2), compared with the case where 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 characteristics contribute.

[0033] The content ratio of the styrene-based monomer units of 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 styrene-based monomer units is within the above range, appropriate flexibility, heat resistance, and mechanical strength can be obtained.

[0034] The content ratio of the styrene-based monomer units of 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 styrene-based monomer units 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).

[0035] The Mw of the polymer (A2) is not limited and can be 50,000 to 500,000, more preferably 70,000 to 400,000, and even more preferably 100,000 to 300,000. In addition, the Mn of the polymer (A2) is not limited and can be 40,000 to 500,000, more preferably 60,000 to 400,000, and even more preferably 80,000 to 280,000. Further, the Mw / Mn of the polymer (A2) is not limited and can be 1.00 to 1.30, more preferably 1.03 to 1.17, and even more preferably 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. It should be noted that the Mw (weight average molecular weight) and Mn (number average molecular weight) of the polymer (A2) can be measured using 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 needed. They can be used alone or in combination of two or more.

[0037] (3-1) Styrene-based polymer block (X2) The styrene-based polymer block (X2) is a polymer block having a styrene-based monomer unit as a main structural unit. The styrene-based monomer unit is a structural unit having styrene and / or a styrene derivative as a monomer. Among them, examples of the styrene derivative include α-methylstyrene, o-methylstyrene, m-methylstyrene, p-methylstyrene, 1,3-dimethylstyrene, p-tert-butylstyrene, etc. They can be used alone or in combination of two or more.

[0038] In the styrene-based monomer unit constituting the styrene-based polymer block (X2), the ratio of the unit derived from styrene (the unit not derived from the styrene derivative) is not limited and can be 50% by mass or more, more preferably 80% by mass or more, even more preferably 90% by mass or more, still more preferably 95% by mass or more, and usually 100% by mass or less with respect to the whole styrene-based polymer block (X2). When the styrene-based polymer block (X2) contains other structural units in addition to styrene-based 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.

[0039] In addition, the polymer (A2) has two or more styrene-based polymer blocks (X2) and two or more conjugated diene compound polymer blocks (Y2), and the styrene-based polymer block (X2) forms at least one molecular end of the polymer (A2). The polymer (A2) can be a linear polymer without a main chain branch or a branched polymer with a main chain branch. They can be used alone or in combination of two or more. Among them, when the polymer (A2) is a linear polymer, the polymer (A2) has the same number of styrene-based polymer blocks (X2) and conjugated diene compound polymer blocks (Y2), or can be in a manner where the number of styrene-based polymer blocks (X2) is one more than the number of conjugated diene compound polymer blocks (Y2). Thus, the styrene-based polymer block (X2) forms at least one molecular end of the polymer (A2).

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

[0041] In addition, as a manner where the number of styrene-based polymer blocks (X2) is one more than the number of conjugated diene compound polymer blocks (Y2), examples include: the structure "X2-Y2-X2-Y2-X2" having 3 styrene-based polymer blocks (X2) and 2 conjugated diene compound polymer blocks (Y2), the structure "X2-Y2-X2-Y2-X2-Y2-X2" having 4 styrene-based polymer blocks (X2) and 3 conjugated diene compound polymer blocks (Y2), etc. That is, various polymers where non-hydrogenated ones are collectively called SBS and hydrogenated ones are collectively called SEBS can be cited. They can be used alone or in combination of two or more. That is, by making the styrene-based polymer block (X2) form at least one molecular end of the polymer (A2), 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 compound polymer block (Y2) The conjugated diene compound polymer block (Y2) is a polymer block mainly composed of conjugated diene compound monomer units. The conjugated diene compound monomer unit is a structural unit with a conjugated diene and / or a conjugated diene derivative as a monomer. Among them, examples of the conjugated diene 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 conjugated diene compound polymer block (Y2), it contains at least a structural unit derived from 1,3-butadiene. Furthermore, the conjugated diene compound polymer block (Y2) is preferably a polymer block mainly composed of 1,3-butadiene monomer units.

[0044] The proportion of the conjugated diene compound monomer unit constituting the conjugated diene compound polymer block (Y2) is not limited. Relative to the whole of the conjugated diene compound polymer block (Y2), 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 conjugated diene compound polymer block (Y2) contains other structural units in addition to the conjugated diene compound monomer unit, the monomer forming the other structural unit is not limited. For example, it can be cited: butene, isobutene, pentene, hexene, 5-ethylidene-2-norbornene, 1,4-hexadiene, etc. They can be used alone or in combination of two or more.

[0045] As described above, the conjugated diene-based polymer block (Y2) contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer units can be either 1,2-vinyl-bonded units [i.e., -CH2-CH(CH=CH2)-] or 1,4-vinyl-bonded units (including cis-1,4-bonds and trans-1,4-bonds) [i.e., -CH2-CH=CH-CH2-]. They can be used alone or in combination of two or more. However, in the present invention, the conjugated diene-based polymer block (Y2) is a block in which the proportion of the structural units derived from 1,2-vinyl bonds is less than 50% by mass. In addition, the structural units derived from 1,4-vinyl bonds and the structural units derived from 1,2-vinyl bonds in the conjugated diene-based polymer block (Y2) may not be hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural units derived from 1,2-vinyl bonds" are structural units derived from monomers having 1,2-vinyl bonds, 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 1,2-vinyl bonds in the conjugated diene-based polymer block (Y2), when the total units derived from 1,3-butadiene monomers are set to 100% by mass, only needs to be less than 50% by mass, preferably 47% by mass or less, more preferably 43% by mass or less, still more preferably 38% by mass or less, and particularly preferably 35% by mass or less. Its lower limit is not limited and can be 0% by mass or more, for example, it can be 5% by mass or more, it can be 10% by mass or more, it can be 15% by mass or more, it can be 20% by mass or more. The above upper and lower limits can be combinations of each other. For example, it can be 0% by mass or more and less than 50% by mass, can further be 10 to 47% by mass, can further be 15 to 43% by mass, can further be 15 to 38% by mass, can further be 20 to 35% 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).

[0047] (4) Polymer (A3) In addition to containing the above polymers (A1) and (A2) as styrene-based polymers (A), the thermoplastic elastomer composition of the present invention may further contain a polymer (A3) as another polymer. That is, the styrene-based polymer (A) may contain only the polymer (A1), may contain only the two polymers (A1) and (A2), may contain only the two polymers (A1) and (A3), or may contain the three polymers (A1), (A2), and (A3).

[0048] The polymer (A3) is a block copolymer having a styrene-based polymer block (X3) and a conjugated diene-based compound polymer block (Y3). Considering that the polymer (A3) has a styrene-based polymer block (X3), the polymer (A3) can also be referred to as a styrene-based polymer (A3). This polymer (A3) can 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 (A3) is a hydride, the hydrogenation rate is not limited and can be 80% or more, can be 90% or more, and can be 100% or less. Since hydrogenation acts on the conjugated diene-based compound polymer block (Y3) in the polymer (A3), the hydrogenation rate is determined by comparing the content ratio of carbon-carbon double bonds in the polymer (A3) before hydrogenation and the polymer (A3) 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-mentioned hydrogenated polymer (A3) can also be referred to as a hydrogenated polymer, a hydrogenated copolymer, a hydrogenated styrene-based polymer, or a hydrogenated styrene-based copolymer. 1 The 1H-NMR analysis.

[0049] In the thermoplastic elastomer composition of the present invention, when the polymer (A3) is contained, compared with the case where the polymer (A3) is not contained, the needle holding performance (needle holding time) tends to be improved. The reason is not clear yet, but by containing the polymer (A3), compared with the case where the polymer (A3) is not contained or the content is small, the MFR tends to decrease and the elongation at break tends to increase. Therefore, it is considered that these characteristics contribute.

[0050] The content ratio of the styrene-based monomer units of the polymer (A3) is not limited. When the entire polymer (A3) is set to 100% by mass, it can be 5% by mass or more, can be further 10% by mass or more, can be further 15% by mass or more, and can be further 20% by mass or more. On the other hand, it can be 90% by mass or less, can be further 70% by mass or less, can be further 60% by mass or less, and can be further 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 be further 10 to 70% by mass, can be further 15 to 60% by mass, and can be further 20 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. It should be noted that the content ratio of the styrene-based monomer units can be measured in the same manner as the method described for the polymer (A1).

[0051] The Mw of the polymer (A3) is not limited and can be from 50,000 to 500,000, can further be from 100,000 to 450,000, and can further be from 200,000 to 350,000. Additionally, the Mn of the polymer (A3) is not limited and can be from 40,000 to 500,000, can further be from 80,000 to 450,000, and can further be from 160,000 to 350,000. Furthermore, the Mw / Mn of the polymer (A3) is not limited and can be from 1.00 to 1.60, can further be from 1.02 to 1.40, and can further be from 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 heat treatment 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. Its application can be the same as that of the polymer (A1).

[0052] It should be noted that the polymer (A3) can 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 ends as needed. They can be used alone or in combination of two or more.

[0053] (4-1) Styrenic polymer block (X3) The styrenic polymer block (X3) 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.

[0054] 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 can be 50% by mass or more, can further be 80% by mass or more, can further be 90% by mass or more, can further be 95% by mass or more, and can generally be 100% by mass or less with respect to the entire styrenic polymer block (X3). 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.

[0055] In addition, the polymer (A3) has two or less styrenic polymer blocks (X3). The polymer (A3) may be a linear polymer without a main-chain branch or a branched polymer with a main-chain branch. They may be used alone or in combination of two or more. Among them, when the polymer (A3) is a linear polymer, examples of its structure include: "X3-Y3", "X3-Y3-X3", "X3-Y3-X3-Y3", etc. That is, various polymers in which non-hydrogenated products are collectively referred to as SBS and hydrogenated products are collectively referred to as SEBS are exemplified. They may be used alone or in combination of two or more.

[0056] It should be noted that in the above "X3-Y3-X3", "X3-Y3-X3-Y3", etc., for the sake of convenience, each X3 represents a styrenic polymer block (X3), and it does not mean that each X3 is the same styrenic polymer block. In the polymer (A3), each X3 may be the same or different. The same applies to each Y3. In addition, the styrenic polymer block (X3) may be the same as or different from the above-mentioned styrenic polymer blocks (X1) and (X2).

[0057] (4-2) Conjugated diene compound polymer block (Y3) The conjugated diene compound polymer block (Y3) is a polymer block mainly composed of conjugated diene compound monomer units. The conjugated diene compound monomer unit is a structural unit with a conjugated diene and / or a conjugated diene derivative as a monomer. Among them, examples of the conjugated diene 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 conjugated diene compound polymer block (Y3), it contains at least a structural unit derived from 1,3-butadiene. Furthermore, the conjugated diene compound polymer block (Y2) is preferably a polymer block mainly composed of 1,3-butadiene monomer units.

[0058] The proportion of the conjugated diene compound monomer unit constituting the conjugated diene compound polymer block (Y3) is not limited, and may be 50% by mass or more, further 80% by mass or more, further 90% by mass or more, further 95% by mass or more, and usually 100% by mass or less with respect to the whole conjugated diene compound polymer block (Y3). When the conjugated diene compound polymer block (Y3) 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, they 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.

[0059] As described above, the conjugated diene compound polymer block (Y3) contains 1,3-butadiene monomer units derived from 1,3-butadiene. The 1,3-butadiene monomer units can be either 1,2-vinyl-bonded units [i.e., -CH2-CH(CH=CH2)-] or 1,4-vinyl-bonded (including cis-1,4-bond and trans-1,4-bond) [i.e., -CH2-CH=CH-CH2-] units. They can be used alone or in combination of two or more. However, in the present invention, the conjugated diene compound polymer block (Y3) is a block in which the proportion of the structural units derived from the 1,2-vinyl bond is less than 50% by mass. In addition, the structural units derived from the 1,4-vinyl bond and the structural units derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y3) may not be hydrogenated, but from the viewpoints of heat resistance and mechanical properties, etc., hydrogenation is preferred. Therefore, the "structural units derived from the 1,2-vinyl bond" are structural units derived from monomers having a 1,2-vinyl bond, meaning structural units including both non-hydrogenated structural units and hydrogenated structural units.

[0060] That is, the proportion of the structural units derived from the 1,2-vinyl bond in the conjugated diene compound polymer block (Y3) only needs to be less than 50% by mass when the total units derived from the 1,3-butadiene monomer are set to 100% by mass. It is preferably 47% by mass or less, more preferably 45% by mass or less, further preferably 43% by mass or less, and particularly preferably 40% by mass or less. Its lower limit is not limited and can be 0% by mass or more. For example, it can be 0% by mass or more, 10% by mass or more, 25% by mass or more, 35% by mass or more. The above upper and lower limits can be combinations of each other. For example, it can be 0% by mass or more and less than 50% by mass, can further be 5 - 47% by mass, can further be 10 - 45% by mass, can further be 25 - 43% by mass, can further be 35 - 40% 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).

[0061] (5) Proportions of the polymers (A1) to (A3) As described above, the styrene-based polymer (A) contains at least the polymer (A1). When the styrene-based polymer (A) is 100% by mass, the proportion of the polymer (A1) is greater than 20% by mass and 80% by mass or less. By making the styrene-based polymer (A) contain the polymer (A1) in an amount greater than 20% by mass and 80% by mass or less, a thermoplastic elastomer composition capable of forming a suppository can be obtained, and the suppository has excellent effects of suppressing liquid leakage from a container 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.

[0062] The content ratio can be further 22% by mass or more, can be further 25% by mass or more, can be further 28% by mass or more, and can be further 30% by mass or more. On the other hand, the content ratio can be 78% by mass or less, can be further 75% by mass or less, can be further 72% by mass or less, and can be further 70% by mass. The above upper and lower limits can be combined with each other. For example, it can be 22 to 78% by mass, can be further 22 to 75% by mass, can be further 25 to 75% by mass, can be further 25 to 72% by mass, can be further 28 to 72% by mass, can be further 28 to 70% by mass, and can be further 30 to 70% by mass. In each of the above ranges, as the range becomes narrower, the liquid leakage suppression performance tends to improve.

[0063] In addition, when the styrene-based polymer (A) does not contain the polymer (A3) and contains the polymers (A1) and (A2), the total content ratio (1) of the polymers (A1) and (A2) is not limited with respect to the entire styrene-based polymer (A). When the styrene-based polymer (A) does not contain the polymer (A2) and contains the polymers (A1) and (A3), the total content ratio (2) of the polymers (A1) and (A3) is not limited with respect to the entire styrene-based polymer (A). These total content ratios (1) and (2) are each preferably more than 50% by mass. When these total content ratios exceed 50% by mass, a thermoplastic elastomer composition capable of forming a suppository can be obtained, and the suppository has more excellent effects of suppressing liquid leakage from a container 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.

[0064] The above total content ratio (1) and the above total content ratio (2) can be further 51% by mass or more, can be further 53% by mass or more, and can be further 55% by mass or more. On the other hand, the upper limit of this total content ratio is not limited, and can be 100% by mass or less, can be further 99% by mass or less, can be further 95% by mass, can be further 90% by mass, can be further 85% by mass, and can be further 80% by mass. The above upper and lower limits can be combinations of each other. For example, it can be greater than 50% by mass and 100% by mass or less, can be further 51 - 100% by mass, can be further 51 - 99% by mass, can be further 53 - 99% by mass, can be further 53 - 95% by mass, can be further 55 - 95% by mass, can be further 55 - 90% by mass, can be further 51 - 90% by mass, can be further 53 - 90% by mass, can be further 53 - 85% by mass, can be further 55 - 85% by mass, and can be further 55 - 80% by mass. In each of the above ranges, as the range narrows, the liquid leakage suppression performance tends to improve.

[0065] "The content ratio (3) of polymer (A1) when the total of polymer (A1) and polymer (A2) is set to 100% by mass when styrene - based polymer (A) does not contain polymer (A3) but contains polymer (A1) and polymer (A2)", and "The content ratio (4) of polymer (A1) when the total of polymer (A1) and polymer (A3) is set to 100% by mass when styrene - based polymer (A) does not contain polymer (A2) but contains polymer (A1) and polymer (A3)" - are not limited. For example, it can be 10% by mass or more, can be further 15% by mass or more, can be further 20% by mass or more, and can be further 25% by mass or more. The upper limit of this ratio is not limited, and can be further 85% by mass or less, can be further 80% by mass or less, can be further 75% by mass or less, and can be further 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 be further 15 - 85% by mass, can be further 15 - 80% by mass, can be further 20 - 80% by mass, can be further 20 - 75% by mass, can be further 25 - 75% by mass, and can be further 25 - 70% by mass. In each of the above ranges, as the range narrows, there is a tendency to improve the liquid leakage suppression performance and the needle holding performance (needle holding time).

[0066] Furthermore, when the styrenic polymer (A) contains three types of polymers, namely polymer (A1), polymer (A2), and polymer (A3), the proportion of polymer (A3) when the total of polymer (A2) and polymer (A3) is set to 100% by mass is not limited. For example, it can be 10% by mass or more, further 15% by mass or more, further 20% by mass or more, and further 25% by mass or more. The upper limit of this proportion is not limited and can be 80% by mass or less, further 75% by mass or less, further 70% by mass or less, and 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, further 15 - 75% by mass, further 20 - 75% by mass, further 20 - 70% by mass, further 25 - 70% by mass, and further 25 - 65% by mass. In each of the above ranges, as the range becomes narrower, the needle holding performance (needle holding time) tends to improve.

[0067] (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.

[0068] The content ratio of the styrenic polymer (A) contained in the thermoplastic elastomer composition is not limited, but in the present invention, it is 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, further 25% by mass or more, and further 30% by mass or more. On the other hand, this content ratio can be 48% by mass or less, further 45% by mass or less, and 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, further 23 - 45% by mass, further 25 - 45% by mass, further 25 - 40% by mass, and further 30 - 40% by mass.

[0069] The total content ratio of the styrenic polymer (A), the softening agent (B), and the olefinic polymer (C) contained in the thermoplastic elastomer composition is not limited, but in the present invention, it is 75 - 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 inserted needle is pulled out after being inserted for a long time. The total content ratio can be further 80% by mass or more, can be further 85% by mass or more, and can be further 90% by mass or more. On the other hand, the content ratio can be 98% by mass or less, can be further 97% by mass or less, and can be further 96% by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 75 - 98% by mass, can be further 80 - 98% by mass, can be further 85 - 98% by mass, can be further 85 - 97% by mass, can be further 90 - 97% by mass, and can be further 90 - 96% by mass.

[0070] (6 - 1) Plasticizer (B) The thermoplastic elastomer composition of the present invention contains a plasticizer (B). By containing the plasticizer (B), the thermoplastic elastomer composition of the present invention can be made soft, and the moldability and elongation at break can be improved. Thereby, a liquid leakage suppressing effect can be obtained. The type of the plasticizer (B) is not limited, and a mineral oil - based plasticizer, a synthetic oil - based plasticizer, etc. can be used. They can be used alone or in combination of two or more. Among them, as the mineral oil - based plasticizer, paraffin - based oil (such as paraffin process oil), naphthenic - based oil (such as naphthenic process oil), liquid paraffin, mineral oil, white oil, etc. can be cited. They can be used alone or in combination of two or more.

[0071] On the other hand, as the synthetic oil - based plasticizer, hydrocarbon - based plasticizers such as α - olefin oligomers, polybutene, alkylbenzenes, cycloalkanes, etc.; ester - based plasticizers such as diesters, polyol esters, phosphate esters, etc.; ether - based plasticizers such as polyethylene glycols, phenyl ethers, etc.; silicone - based plasticizers such as polydimethylsiloxanes, silicate esters, etc.; fluorine - based plasticizers such as trifluoroethylene, etc. can be cited. 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 styrene - based polymer (A), paraffin - based oil, naphthenic - based oil, and their mixture are preferred, and paraffin - based oil is particularly preferred.

[0072] The kinematic viscosity of the plasticizer (B) is not limited, but from the viewpoint of suppressing volatilization or bleeding during heating during manufacturing or use, etc., it is preferably 10 mm 2 / s or more, more preferably 50 mm 2 / s or more, and further preferably 100 mm 2 / s or more. On the other hand, from the viewpoint of operability, it is preferably 800 mm 2 / s or less, more preferably 600 mm 2 / s or less, and further preferably 500 mm 2 / s or less. In addition, the kinematic viscosity is the value at 40 °C based on JIS Z8803.

[0073] The Mw of the softening agent (B) is not limited and may be 500 to 3000, and may further be 800 to 1500. Within this range, it is easy to obtain a thermoplastic elastomer composition that is soft, has low 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 described below. · 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 / min · 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)

[0074] 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 may 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 penetration resistance is low 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) may be 90 parts by mass or more, may further be 100 parts by mass or more, and may further be 120 parts by mass or more. On the other hand, the upper limit may be 280 parts by mass or less, may further be 250 parts by mass or less, may further be 220 parts by mass or less, and may further be 200 parts by mass or less. The above upper and lower limits can be combinations of each other. For example, it may be 90 to 250 parts by mass, may further be 90 to 220 parts by mass, may be 100 to 220 parts by mass, and may be 100 to 200 parts by mass.

[0075] (6-2) Olefin-based polymer (C) The thermoplastic elastomer composition of the present invention contains an olefin-based polymer (C). By containing the olefin-based polymer (C), the thermoplastic elastomer composition of the present invention can be given appropriate moldability (formability) and mechanical strength. The olefin-based 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-based 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, can be further 90% or more. On the other hand, its 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, examples include: acrylic acid, methacrylic acid, maleic acid, acrylate, methacrylate, vinyl acetate, etc. They can be used alone or in combination of two or more.

[0076] The kind of olefin as the monomer constituting the olefin-based polymer (C) is not limited, and examples include: 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-based polymer (C), it includes polyethylene, polypropylene, polybutene, etc. These polymers can be used alone or in combination of two or more. That is, the olefin-based 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-based polymer (C) is preferably polypropylene, and particularly preferably a homopolymer of propylene.

[0077] Among the above, as polyethylene, examples include: ethylene homopolymer, and copolymers of ethylene and other olefins. As copolymers of ethylene and other olefins, examples include: ethylene-1-butene copolymer, ethylene-1-octene copolymer, etc. These copolymers can be random copolymers or block copolymers. It should be noted that the copolymer of ethylene and other olefins is a polymer in which 50% or more of all the structural unit numbers are structural units derived from ethylene.

[0078] 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 copolymer of propylene and other olefins is a polymer in which more than 50% of all the structural units are structural units derived from propylene.

[0079] The MFR (melt flow rate) of the olefin 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 under a load of 21.2 N at 230 °C based on ASTM D1238.

[0080] Furthermore, the flexural modulus of the olefin 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 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 in accordance with JIS K6921-2 (test piece: 80 mm × 10 mm × 4 mm, test speed: 2 mm / minute).

[0081] The content of the olefin polymer (C) is not limited. For example, when the total amount of the styrene 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 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, and 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, and 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, and can further be 10 to 35 parts by mass.

[0082] (6-3) Other components In addition to the above-mentioned styrenic polymer (A), softening agent (B), and olefinic polymer (C), the thermoplastic elastomer composition of the present invention may further contain other components. As the other components, for example, the following can be cited: fillers, other thermoplastic polymers other than the styrenic polymer (A) and olefinic polymer (C), colorants, pigments, antistatic agents, antibacterial agents, mildew-proof 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 in combination of two or more.

[0083] As described above, the total content ratio of the styrenic polymer (A), softening agent (B), and olefinic polymer (C) contained in the thermoplastic elastomer composition of the present invention is 75 to 99% by mass. Therefore, the content ratio of the other components is 1 to 25% by mass. The content ratio of the other components can be 2% by mass or more, can be further 3% by mass or more, and can be further 4% by mass or more. On the other hand, the content ratio of the other components can be 20% by mass or less, can be further 15% by mass or less, and can be further 10% by mass or less. The above upper and lower limits can be in various combinations, for example, can be 2 to 25% by mass, can be further 2 to 20% by mass, can be further 2 to 15% by mass, can be further 3 to 15% by mass, can be further 3 to 10% by mass, and can be further 4 to 10% by mass.

[0084] (6-3-1) Filler (D) Among the above other components, as the filler (D), the following can be cited: inorganic fillers and organic fillers. They can be used alone or in combination of two or more. As the inorganic fillers, the following can be cited: talc, clay, wollastonite, silica, zeolite, hydrotalcite, silica, calcium silicate, magnesium silicate, sodium aluminate, calcium aluminate, sodium aluminosilicate, glass, alumina, magnesia, calcium carbonate (light calcium carbonate, heavy calcium carbonate, etc.), zinc carbonate, antimony trioxide, potassium titanate, boron nitride, metal fibers, metal whiskers, ceramic whiskers, carbon black, graphite, carbon fibers, etc. They can be used alone or in combination of two or more. As the organic fillers, the following can be cited: starch, cellulose, wood powder, okara, bran, resin fibers, etc. They can be used alone or in combination of two or more.

[0085] Among the above, in the thermoplastic elastomer composition of the present invention, inorganic fillers are 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 is 0.05 to 50 μm, may further be 0.1 to 40 μm, may further be 0.5 to 30 μm, may further be 1.0 to 20 μm.

[0086] It should be noted that the particle size distribution of D50 is measured 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.

[0087] When the filler (D) is contained, its content is not limited. For example, when the total amount of the styrene-based polymer (A) is set to 100 parts by mass, the filler (D) can be 0.5 to 100 parts by mass. Within this range, there is a tendency to improve the liquid leakage suppression performance and the needle holding performance (needle holding time). The lower limit of the content of the filler (D) can be 1 part by mass or more, may further be 2 parts by mass or more, may further be 5 parts by mass or more, may further be 7 parts by mass or more, may further be 10 parts by mass or more. On the other hand, the upper limit can be 80 parts by mass or less, may further be 70 parts by mass or less, may further be 60 parts by mass or less, may further be 50 parts by mass or less. The above upper and lower limits can be combinations of each other. For example, it can be 1 to 80 parts by mass, may further be 2 to 80 parts by mass, may further be 2 to 70 parts by mass, may further be 5 to 70 parts by mass, may further be 5 to 60 parts by mass, may further be 7 to 60 parts by mass, may further be 7 to 50 parts by mass, may further be 10 to 50 parts by mass.

[0088] (6-3-2) Other thermoplastic polymers Among the above other components, examples of other thermoplastic polymers include: other styrene-based polymers (E) other than the styrene-based polymer (A), other ethylene-based polymers other than the olefin-based polymer (C), polyamide-based polymers, polyester-based polymers, acrylic-based polymers, methacrylic-based polymers, rosin-based resins, petroleum resins, and the like.

[0089] Among the above, examples of other styrene-based polymers (E) include: styrene polymers, α-methylstyrene polymers, styrene-α-methylstyrene copolymers, etc. Examples of other ethylene-based polymers include: ethylene-vinyl acetate copolymers, ethylene-acrylic acid copolymers, ethylene-methacrylic acid copolymers, ethylene-acrylate copolymers, ethylene-methacrylate copolymers, etc. Examples of polyamide-based polymers include: nylon 6, nylon 66, etc. Examples of polyester-based polymers include: polyethylene terephthalate, polybutylene terephthalate, etc. Examples of rosin-based resins include: rosin ester resins, etc. Examples of petroleum resins include: C5-based petroleum resins, C9-based petroleum resins, and hydrogenated petroleum resins obtained by hydrogenating them, etc. They can be used alone or in combination of two or more.

[0090] Among the above, other styrene-based polymers (E) may also be contained. Further, as other styrene-based 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 entire 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.

[0091] Further, from the viewpoint of moldability, other styrene-based polymers (E) are preferably lower in molecular weight than the styrene-based polymer (A). Its molecular weight is not limited. For example, a styrene-based polymer with Mw of 1000 - 30000, Mn of 800 - 20000, and Mw > Mn can be used. By containing such other styrene-based 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-based polymers can be called tackifiers.

[0092] Regarding the above molecular weight range of other styrene-based polymers (E), Mw can be further 1200 - 25000, can be further 1500 - 20000, can be further 2000 - 15000. In addition, Mn can be further 1000 - 8000, can be further 1500 - 7000, can be further 2000 - 6000. It should be noted that the Mw (weight-average molecular weight) and Mn (number-average molecular weight) of other styrene-based polymers (E) can be measured by gel permeation chromatography. Its operation is the same as that of the polymer (A1).

[0093] In addition, the softening point of the other styrene-based polymer (E) is not limited. For example, with respect to the softening point based on ASTM E28, it can be 80 to 200°C, further can be 90 to 180°C, and further can be 100 to 160°C. By containing such other styrene-based polymer (E), the effect of improving the heat resistance of the thermoplastic elastomer composition of the present invention is achieved.

[0094] Examples of such other styrene-based 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.

[0095] 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.

[0096] When containing the other styrene-based polymer (E), the content of the other styrene-based polymer (E) 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 0.1 to 50 parts by mass. Within this range, the effect of suppressing liquid leakage and the needle holding property can be improved. The lower limit of the content of the other styrene-based polymer (E) can be 0.5 parts by mass or more, further can be 1.0 parts by mass or more, further can be 1.5 parts by mass or more, and further can be 2.0 parts by mass or more. On the other hand, the upper limit can be 45 parts by mass or less, further can be 35 parts by mass or less, further can be 25 parts by mass or less, and further can 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, further can 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.

[0097] (7) Regarding others of 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 retention 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, can further be 14 to 34. This A hardness is a value measured according to the measurement method of the examples described later.

[0098] 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, can be 2.0 to 75 g / 10 minutes. This MFR is a value measured according to the measurement method of the examples described later.

[0099] Furthermore, from the viewpoint of the liquid leakage suppressing 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, can be 2.5 to 5.5 MPa. This tensile strength is a value measured according to the measurement method of the examples described later.

[0100] In addition, from the viewpoint of the liquid leakage suppressing effect, 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 later.

[0101] Furthermore, from the viewpoint of the liquid leakage suppressing effect, 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 later.

[0102] 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.

[0103] 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 medicinal suppository for a medical container (medical container plug body), various connecting tubes such as an infusion set, a liquid medicine container, a mixing injection plug for hemodialysis, and a sealing member for a medical vial or a blood collection tube. Examples

[0104] Hereinafter, the present invention will be described in more detail based on examples. However, these examples are only examples shown for the convenience of explanation, and the present invention is not limited to these examples in any sense.

[0105] [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 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 relative 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 16 and Comparative Examples 1 to 14. 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 to 240 °C · Screw rotation speed: 300 revolutions per minute

[0106] [Table 1]

[0107] [Table 2]

[0108] [Table 3]

[0109] The respective raw material components 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 terminals), content ratio of styrene-based monomer units: 32% by mass, Mw: 240,000, Mn: 220,000, Mw / Mn: 1.09, proportion of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y1): 67% by mass)

[0110] (1-2) Polymer (A2) SEBS (manufactured by Kraton Polymers, product name "A1535", X2-Y2-X2-Y2-X2 type multiblock hydrogenated copolymer (having 3 X2s and 2 Y2s, X2 forms two molecular terminals), content ratio of styrene-based monomer units: 58% by mass, Mw: 270,000, Mn: 250,000, Mw / Mn: 1.08, proportion of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y2): 30% by mass)

[0111] (1-3) Polymer (A3) SEBS (manufactured by Kraton Polymers, product name "G1651H", X1-Y1-X1 type triblock hydrogenated copolymer (having 2 X3s, X3 forms two molecular terminals), content ratio of styrene-based monomer units: 33% by mass, Mw: 290,000, Mn: 260,000, Mw / Mn: 1.12, proportion of structural units from 1,2-vinyl bonds in the conjugated diene-based compound polymer block (Y3): 37% by mass)

[0112] (2) Softener (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.

[0113] (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 of elasticity: 1650 MPa)

[0114] (4) Filler (D) Talc filler (talc, manufactured by Hayashi Kasei Co., Ltd., product name "TP-TK", D50: 11 μm)

[0115] (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)

[0116] [2] Preparation of molded articles for evaluation (1) The pellets composed of the thermoplastic elastomer compositions of Examples 1 to 16 and Comparative Examples 1 to 14 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 Shore A hardness, tensile strength, elongation at break, and tear strength. These measurements are described later.

[0117] (2) The pellets composed of the thermoplastic elastomer compositions of Examples 1 to 16 and Comparative Examples 1 to 14 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 punched out from this columnar molded article and molded. This substantially cylindrical molded body was used as a plug for the evaluation described later. These evaluations are described later.

[0118] (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

[0119] [3] Various measurements (1) MFR The MFR of the pellets composed of the thermoplastic elastomer compositions (Examples 1 to 16 and Comparative Examples 1 to 14) obtained in [1] above was measured according to ASTM D1238 under the temperature condition of 230 °C and the nominal load of 21.2 N. In addition, in this measurement, a testing machine (product name "Melt Flow Indexer G-02") manufactured by Toyo Seiki Co., Ltd. was used. The results are shown in Tables 1 to 3. "NF" in the tables means non-flowing, and the moldability is significantly poor.

[0120] (2) Shore A hardness The sheet-shaped molding (thickness: 2 mm) obtained in [2](1) above was subjected to conditioning for 1 day at a temperature of 23°C and a humidity of 50%, and then 3 conditioned sheet-shaped moldings were overlapped (total 6 mm) to form a laminate. On this basis, the A hardness of the laminate was measured (Examples 1 to 16 and Comparative Examples 1 to 14). Specifically, according to 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.

[0121] (3) Tensile strength The sheet-shaped molding (thickness: 2 mm) obtained in [2](1) above was subjected to conditioning for 1 day at a temperature of 23°C and a humidity of 50%, and then a dumbbell No. 3 test piece was punched out from the conditioned sheet-shaped molding. Using the obtained dumbbell No. 3 test piece, the tensile strength was measured in accordance with JIS K6251 (Examples 1 to 16 and Comparative Examples 1 to 14). Specifically, using a tensile testing machine (manufactured by Shimadzu Corporation, model "Auto graph AG-50kND"), the maximum tensile force recorded when the test piece was stretched until fracture was measured under the conditions of a temperature of 23°C and a tensile speed of 500 mm / minute. 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.

[0122] (4) Elongation at break The sheet-shaped molding (thickness: 2 mm) obtained in [2](1) above was subjected to conditioning for 1 day at a temperature of 23°C and a humidity of 50%, and then a dumbbell No. 3 test piece was punched out from the conditioned sheet-shaped molding. Using the obtained dumbbell No. 3 test piece, the tensile strength was measured in accordance with JIS K6251 (Examples 1 to 16 and Comparative Examples 1 to 14). 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 tensile speed of 500 mm / minute, and the elongation at break (the 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.

[0123] (5) Tear strength The sheet-shaped molded article (thickness: 2 mm) obtained in the above [2](1) was subjected to conditioning for 1 day at a temperature of 23°C and a humidity of 50%, 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 16 and Comparative Examples 1 to 14). 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 when the test piece was stretched until fracture was measured. Then, the value obtained by dividing this 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.

[0124] [4] Preparation of the suppository and evaluation of the suppository body (1) Preparation of the suppository Each suppository body (a 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 16 and Comparative Examples 1 to 14 obtained in the above [2](2) 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 above integrated product, thereby obtaining the suppository (Examples 1 to 16 and Comparative Examples 1 to 14).

[0125] (2) Preparation of the flexible bag for infusion 500 ml of water was injected into the flexible bag that became an infusion bag with an internal volume of 700 ml, and then the injection port of the flexible bag was sealed with the suppository to obtain a test flexible bag for infusion.

[0126] (3) Measurement of the liquid leakage rate The flexible bag for infusion obtained in the above [4](2) was hung from a bracket with the suppository facing downwards. Next, at the central portion of the suppository body exposed from the non-contact liquid surface side of the suppository, a medical plastic needle (manufactured by Nipro Corporation, model "ISA-600A00Z") was inserted through from the lower side of the suppository body. At this time, the medical plastic needle was inserted through in a manner perpendicular to the exposed surface of the suppository body and inserted until the root of the medical plastic needle contacted the exposed surface of the suppository 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 was sealed and used.

[0127] After the above-mentioned insertion, let it stand for 24 hours, 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 removal to 1 minute, but water droplets adhere to the needle hole", and "state where liquid dripping occurs during the period from needle removal to 1 minute before, but the liquid dripping stops after 1 minute" as liquid leakage. This evaluation is carried out for each of the 10 samples in Examples 1 to 16 and Comparative Examples 1 to 14, and the proportion (%) of the number of samples confirmed to have liquid leakage is calculated. The results are shown in Tables 1 to 3. That is, the liquid leakage rate in the case where liquid leakage occurs in all 10 tests is set to 100%, and the liquid leakage rate in the case where no liquid leakage is found in the 10 tests is set to 0%. It should be noted that the tests are carried out in a room at a temperature of 23°C and a humidity of 50%.

[0128] (4) Liquid leakage property (score evaluation) Regarding the test specimens confirmed to have liquid leakage 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. The score corresponding to case [A] is set to "1 point", the score corresponding to case [B] is set to "3 points", the score corresponding to case [C] is set to "3 points", and the score corresponding to case [D] is set to "6 points". Calculate the total score of the 10 test specimens. The results are shown in Tables 1 to 3.

[0129] [A]: "The state where no liquid dripping is observed from the time of needle removal to 1 minute, and no water droplets are observed on the needle hole at 1 minute." [B]: "The state where no liquid dripping is observed from the time of needle removal to 1 minute, but water droplets adhere to the needle hole." [C]: "The state where liquid dripping occurs during the period from needle removal to 1 minute before, but the liquid dripping stops at 1 minute." [D]: "The state where liquid drips from the needle hole at 1 minute."

[0130] (5) Needle holding time Hang the flexible infusion bag obtained in the above [4](2) with the medicine plug facing down from the bracket. Next, a medical metal needle (manufactured by Nipro Corporation, model "TC-00501K") is inserted through the center of the plug body exposed from the non-contact liquid level side of the suppository, 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 suppositories of each infusion soft bag are arranged such that the exposed surface of the plug body is parallel to the horizontal plane of the test stand. Further, a 500 g weight is installed on the medical metal needle, and the weight is arranged to hang vertically below the exposed surface of the plug body. In addition, during the test, in order to prevent 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, the time from the above insertion until the medical metal needle falls off is measured and counted as the needle holding time (unit: "seconds"), and the results are shown in Tables 1 to 3.

[0131] [5] Effects of the Examples Taking the content (mass %) of the styrene-based polymer (A) when the thermoplastic elastomer composition is 100 mass % as Composition Condition 1, Composition Condition 1 of the thermoplastic elastomer composition of the present invention is 20 to 50 mass %. Taking the total content (mass %) of the styrene-based polymer (A), the softening agent (B), and the olefin-based resin (C) when the thermoplastic elastomer composition is 100 mass % as Composition Condition 2, Composition Condition 2 of the thermoplastic elastomer composition of the present invention is 75 to 99 mass %. Taking the content (mass %) of the polymer (A1) when the styrene-based polymer (A) is 100 mass % as Composition Condition 3, Composition Condition 3 of the thermoplastic elastomer composition of the present invention is greater than 20 mass % and 80 mass % or less.

[0132] Examples 1 to 5 are examples that use the polymer (A1) and the polymer (A2) to satisfy Composition Condition 1, further use a filler or other styrene-based polymer (E) to satisfy Composition Condition 2, and satisfy Composition Condition 3 when using a softening agent and an olefin-based polymer, showing excellent liquid leakage inhibition effects and good needle holding performance. On the other hand, Comparative Example 1 that does not use the polymer (A1) and does not satisfy Composition Conditions 1 and 3 has poor liquid leakage inhibition effects and needle holding performance. In addition, similarly in Comparative Example 7, due to insufficient affinity with the softening agent or the olefin-based resin, the measurement sample cannot be molded. Further, in Comparative Example 2 that uses the polymer (A1) and the polymer (A2) but does not satisfy Composition Condition 2, the liquid leakage inhibition effect and the needle holding performance are poor.

[0133] Example 6 is an example in which polymer (A3) is used instead of polymer (A2) in Example 2, and the liquid leakage suppression effect and needle holding performance are good. However, the liquid leakage rates of Comparative Example 3 with Composition Condition 2 being 100% by mass and Comparative Example 6 with Composition Condition 2 being 62% by mass are 100%, and the needle holding performance is also poor. Comparative Examples 4 and 5 are compositions in which the softening agent component in Examples 2 and 6 is reduced but does not satisfy Composition Condition 1. Due to the high A hardness, the needle holding performance is excellent, but the liquid leakage rate reaches 100%.

[0134] Examples 7 and 8 are examples in which polymer (A3) is further used relative to Example 4. Compared with Example 4, the liquid leakage suppression effect is the same, and the needle holding performance is more excellent. Comparative Examples 9 and 10 are examples in which Composition Condition 3 is 20% by mass and 10% by mass, respectively, and do not satisfy Composition Condition 3. Compared with Examples 7 and 8, the reduction in the liquid leakage suppression effect is large, and the needle holding performance is also poor. In addition, although Comparative Examples 11 and 12 satisfy Composition Conditions 1 and 3, Composition Condition 2 is 100%, and the results compared with Examples 7 and 8 show poor liquid leakage suppression effect and needle holding performance.

[0135] Examples 9 to 12 are examples in which the composition ratios of polymer (A1), polymer (A2), and polymer (A3) are changed within the range satisfying Composition Conditions 1 to 3. Compositions with excellent liquid leakage suppression effect and needle holding performance are obtained. However, in Comparative Examples 13 and 14, Composition Condition 2 is not satisfied, and the liquid leakage rates reach 90% and 100%, respectively, and the needle holding performance is poor. In Examples 13 and 14, polymer (A1) and polymer (A2) are used, and Examples 15 and 16 are compositions in which polymer (A3) is further used. They are examples in which other styrene-based polymers (E) are used within the range satisfying Composition Conditions 1 to 3. Excellent results of liquid leakage suppression effect and needle holding performance are shown.

[0136] From the above results, it can be seen that the thermoplastic elastomer composition of the present invention has excellent liquid leakage suppression effect and needle holding performance, and is particularly applicable to the plug body of a medicine plug of a medical container involving a puncture operation, etc. Industrial Applicability

[0137] The thermoplastic elastomer composition of the present invention can be used for any purpose, but can be widely used in 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) contains a styrenic block copolymer having a styrenic polymer block (X1) and a conjugated diene compound polymer block (Y1), i.e., polymer (A1). The proportion of the structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y1) constituting the polymer (A1) is 50% by mass or more. When the entire thermoplastic elastomer composition is set to 100% by mass, the styrenic polymer (A) is 20 to 50% by mass, and the total of the styrenic polymer (A), the softening agent (B), and the olefinic polymer (C) is 75 to 99% by mass. When the styrenic polymer (A) is set to 100% by mass, the polymer (A1) is more than 20% by mass and 80% by mass or less.

2. The thermoplastic elastomer composition according to claim 1, further comprising a filler (D) and / or a tackifier (E).

3. The thermoplastic elastomer composition according to claim 1, wherein, The styrenic polymer (A) further contains a polymer (A2) as a styrenic block copolymer. The polymer (A2) has 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 the structural units derived from 1,2-vinyl bonds in the conjugated diene compound polymer block (Y2) is less than 50% by mass.

4. The thermoplastic elastomer composition according to claim 1, wherein, The styrenic polymer (A) further contains a polymer (A3) as a styrenic block copolymer. The polymer (A3) has 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.

5. A thermoplastic elastomer composition for a medical container stopper, characterized in that, Containing the thermoplastic elastomer composition according to any one of claims 1 to 4.

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