JP5350922B2 - Thermoplastic elastomer resin composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer that is easy to mold, has excellent sealing properties, gas barrier properties, heat-resistant deformation properties, and has low elution properties, and a medical rubber stopper and packing using the same. .

  Conventionally, as a rubber composition for producing a medical rubber stopper such as a rubber stopper of an injection container, a composition mainly composed of various synthetic rubbers has been used. Among these, a butyl rubber ( Butyl rubber (isobutylene-isoprene copolymer), chlorinated butyl rubber, brominated butyl rubber, brominated product of isobutylene-paramethylstyrene copolymer) based on polyisobutylene skeleton has gas permeability such as oxygen and water vapor. Since it is low and has excellent gas barrier properties, it has been put to practical use as the most suitable material.

  When producing rubber plugs using these butyl rubbers, there are crosslinking agents (or vulcanizing agents) and crosslinking aids that must be used in the production of such rubber plugs. Even when a simple organic peroxide is used, a decomposition product or a secondary reaction product of the crosslinking agent remains in the crosslinked rubber, and remains even after each processing step of the rubber plug. Especially in the case of butyl rubber, these crosslinkers and crosslinkers are extremely difficult to diffuse, elute and volatilize during the production process, and evaporate and leach out of the system over a long period of time. However, it is not preferable as a medical rubber stopper that is required. In general, when a rubber is cross-linked, a long heating and pressing step is required at a high temperature.

  In order to simplify this cross-linking process, a technique has been proposed in which a thermoplastic elastomer that does not require cross-linking is used and molding is performed in a short time using an injection molding machine or the like. As a technique using such a thermoplastic elastomer, a stopper comprising a hydrogenated derivative of a block copolymer composed of an aromatic vinyl compound and a conjugated diene, a softener for rubber, and an olefin resin (Patent Documents 1 and 2) And gaskets for syringes (Patent Documents 3 and 4). Since these technologies do not require a crosslinking step, there are no elution substances derived from crosslinking agents, but general rubber softeners have high elution properties for alcohol-based drugs and a large gas permeability coefficient. There was a problem that the gas barrier property against the liquid was insufficient.

  Thus, as a medical sealable article using a thermoplastic elastomer with improved gas barrier properties, a product using a block copolymer of an aromatic vinyl compound and isobutylene has been proposed (Patent Document 5). This technology uses a polyisobutylene structure similar to that of conventional butyl rubber, so it has excellent gas barrier properties but lacks heat distortion resistance. There was a problem.

  Furthermore, isobutylene-isoprene copolymer rubber (butyl rubber) is operated in the presence of an olefin resin and a hydrogenated diene copolymer as a stopper for a medical container comprising a thermoplastic elastomer with improved heat distortion resistance. Cross-linked ones have been proposed (Patent Document 6). However, even in this technique, a general problem that has been used in conventional butyl rubbers is used as a crosslinking agent or a crosslinking aid, so that there remains a problem of elution.

  Furthermore, as a medical container stopper made of a thermoplastic elastomer with improved heat distortion resistance and dissolution properties, it softens with a composition in which an isobutylene polymer is dynamically cross-linked with a hydrosilyl group-containing compound in the presence of an olefin resin. The thing which consists of an agent is proposed (patent document 7). However, even in this technique, in the case of alcohol-based drugs, there is a problem of elution of the softener, and all the problems have not been solved.

JP-A 61-37242 Japanese Patent Publication No.2-4296 Japanese Patent Publication No. 2-17578 JP-B-2-17579 JP-A-5-212104 Japanese Patent No. 3700215 WO2007 / 119687

  An object of the present invention is to provide a thermoplastic elastomer that is easy to mold, has excellent sealing properties, gas barrier properties, heat-resistant deformation properties, and has low elution properties, and medical rubber stoppers and packings using the same. There is to do.

As a result of intensive studies to solve the above problems, the present inventors have achieved the following invention.
That is, the present invention includes 100 parts by weight of polyisobutylene (A) having a crosslinkable functional group,
10 to 100 parts by weight of polyisobutylene (B) having a weight average molecular weight of 40,000 to 80,000 having no crosslinkable functional group;
10 to 100 parts by weight of a polyolefin resin (C),
In the component (B) and the component (C), the hydrosilyl group-containing compound (D) is 0.1 to 10 parts by weight, and the component (A) is dynamically cross-linked while being melt-kneaded with the component (D). The present invention relates to a thermoplastic elastomer.

  In a preferred embodiment, the present invention relates to a thermoplastic elastomer, wherein the polyisobutylene (A) having a crosslinkable functional group is a polyisobutylene having an allyl group at a terminal.

  A preferred embodiment relates to a thermoplastic elastomer characterized in that the polyisobutylene (A) having a crosslinkable functional group has a weight average molecular weight of 40,000 to 80,000.

  As a preferred embodiment, the present invention relates to a thermoplastic elastomer characterized in that the polyolefin resin (C) is polypropylene.

  As a preferred embodiment, the present invention relates to a thermoplastic elastomer, wherein the hydrosilyl group-containing compound is either polymethylhydrogensiloxane or a copolymer of dimethylsiloxane and methylhydrogensiloxane.

  As a preferred embodiment, further contains 1 to 50 parts by weight of an isobutylene block copolymer (E) comprising a polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene polymer block (b). The present invention relates to a thermoplastic elastomer.

  Furthermore, the present invention relates to a medical rubber stopper containing the thermoplastic elastomer described above.

  Furthermore, this invention relates to the medical packing characterized by containing the thermoplastic elastomer of the said description.

  The thermoplastic elastomer of the present invention is easy to mold, has excellent sealing properties, gas barrier properties, and heat distortion resistance, and has low elution properties. Therefore, the medical rubber plug and packing containing the thermoplastic elastomer not only have good shape followability at the time of sealing, but also oxidative deterioration due to the permeation of oxygen to the contents such as injections and vacuum in the vacuum blood collection tube. Degradation is unlikely to occur. Further, since the crosslinking is performed by the hydrosilyl group-containing compound, the heat distortion resistance can be greatly improved while maintaining the property that the component elution from the rubber stopper is very small. As a result, it is possible to obtain a medical rubber plug that is easy to mold, has excellent sealing properties and gas barrier properties, has low elution properties, and has good needle penetration. Therefore, it is suitable for injection containers such as vials and prefilled syringes, rubber stoppers such as vacuum blood collection tubes, and packing.

  The thermoplastic elastomer of the present invention comprises 100 parts by weight of polyisobutylene (A) having a crosslinkable functional group, and 10 to 100 parts by weight of polyisobutylene (B) having a weight average molecular weight of 40,000 to 80,000 having no crosslinkable functional group. And 10 to 100 parts by weight of the polyolefin resin (C) and 0.1 to 10 parts by weight of the hydrosilyl group-containing compound (D). In the component (B) and the component (C), the component (A) It can be obtained by dynamically crosslinking with component (D) while melt-kneading.

  The polyisobutylene (A) having a crosslinkable functional group of the present invention is a crosslinkable functional group in which units derived from isobutylene account for 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. It means polyisobutylene. The monomer other than isobutylene is not particularly limited as long as it is a monomer component capable of cationic polymerization, but aromatic vinyls, aliphatic olefins, dienes such as isoprene, butadiene, divinylbenzene, vinyl ethers, β -Monomers such as pinene can be exemplified. These may be used alone or in combination of two or more. The molecular weight of the component (A) is preferably 40,000 to 300,000, particularly preferably 40,000 to 80,000, as a weight average molecular weight as measured by GPC. When the weight average molecular weight is less than 40,000, the extractability tends to deteriorate, and when it exceeds 300,000, the melt-kneading property tends to decrease, and the reactivity during crosslinking tends to decrease.

  The crosslinkable functional group in the polyisobutylene having a crosslinkable functional group of the present invention is not particularly limited as long as it is crosslinkable with the hydrosilyl group-containing compound (D), but from the viewpoint of reactivity, an alkenyl group, particularly an allyl group. From the viewpoint of mechanical properties, adhesiveness, and compression set characteristics, the functional group is preferably at the terminal.

  The method for introducing the crosslinkable functional group of the component (A) of the present invention is not particularly limited. For example, as a method for introducing an allyl group at the terminal, Japanese Patent Application Laid-Open No. 3-152164 and Japanese Patent Application Laid-Open No. 7-304909. A method of introducing an unsaturated group into a polymer by reacting a compound having an unsaturated group with a polymer having a functional group such as a hydroxyl group as disclosed. In order to introduce an unsaturated group into a polymer having a halogen atom, a method of performing a Friedel-Crafts reaction with allyl phenyl ether, a method of performing a substitution reaction with allyltrimethylsilane in the presence of a Lewis acid, various phenols, etc. And the above-mentioned allyl group introduction reaction after the introduction of a hydroxyl group by the Friedel-Crafts reaction. Among these, those in which an allyl group is introduced at the terminal by a substitution reaction of allyltrimethylsilane and chlorine are preferable from the viewpoint of reactivity.

  The amount of the allyl group in the component (A) of the present invention can be arbitrarily selected depending on the required properties, but from the viewpoint of the properties after crosslinking, it has at least 0.2 allyl groups per molecule at the end. It is preferably a polymer, more preferably 1.0 or more per molecule, and most preferably 1.5 or more per molecule. If it is less than 0.2, the crosslinking reaction may not proceed sufficiently.

  The polyisobutylene (B) of the present invention refers to a polyisobutylene having no crosslinkable functional group in which units derived from isobutylene account for 70% by weight or more, preferably 90% by weight or more, more preferably 95% by weight or more. The monomer other than isobutylene is not particularly limited as long as it is a monomer component capable of cationic polymerization, and examples thereof include monomers such as aromatic vinyls, aliphatic olefins, vinyl ethers, and β-pinene. These may be used alone or in combination of two or more. The molecular weight of the component (B) is preferably from 30,000 to 150,000, particularly preferably from 40,000 to 80,000, as a weight average molecular weight as measured by GPC. When the weight average molecular weight is less than 30,000, the extractability tends to deteriorate. When the weight average molecular weight exceeds 150,000, the viscosity of the compound increases and the moldability deteriorates, and the compression set characteristics deteriorate. there is a possibility.

  The addition amount of the polyisobutylene (B) is 10 to 100 parts by weight, preferably 10 to 80 parts by weight, and most preferably 10 to 60 parts by weight with respect to 100 parts by weight of the component (A). When the component (B) is less than 10 parts by weight, sufficient molding fluidity and flexibility tend not to be obtained. When the component is more than 100 parts by weight, the compression set characteristics are impaired and sufficient sealing performance is not exhibited. Tend.

  The polyolefin resin which is the component (C) of the present invention is an α-olefin homopolymer, a random copolymer, a block copolymer and a mixture thereof, or an α-olefin and another unsaturated monomer. Random copolymers, block copolymers, graft copolymers and oxidized, halogenated or sulfonated ones of these polymers can be used alone or in combination. Specifically, polyethylene, ethylene-propylene copolymer, ethylene-propylene-nonconjugated diene copolymer, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate Copolymers, ethylene-vinyl alcohol copolymers, ethylene-ethyl acrylate copolymers, ethylene-acrylic acid copolymers, ethylene-methyl acrylate-maleic anhydride copolymers, polyethylene resins such as chlorinated polyethylene, Polypropylene resins such as polypropylene, propylene-ethylene random copolymer, propylene-ethylene block copolymer, chlorinated polypropylene, poly-1-butene, polyisobutylene, polymethylpentene, cyclic olefin (co) polymer, etc. It can be illustrated. Among these, polyethylene, polypropylene, or a mixture thereof can be preferably used from the viewpoint of balance between cost and physical properties. Examples of the polyethylene include high density polyethylene, low density polyethylene, and linear low density polyethylene. Examples of the polypropylene include homopolypropylene, random polypropylene, and block polypropylene. Among these, polypropylene is most preferable from the viewpoint of heat resistance.

  The melt flow rate (MFR) of the polyolefin-based resin to be used is not particularly limited, but is preferably 0.1 to 100 (g / 10 min) from the viewpoint of molding fluidity, and is preferably 1 to 100 (g / 10 min) is more preferable.

  In the present invention, the component (C) not only functions as a crosslinking reaction field for the component (A), but also imparts molding fluidity, heat resistance, mechanical strength, slidability, etc. to the final composition. Have Component (C) is added in an amount of 10 to 100 parts by weight, preferably 10 to 80 parts by weight, and most preferably 10 to 50 parts by weight per 100 parts by weight of component (A). When the amount of the component (C) is less than 10 parts by weight, there is a tendency that sufficient molding fluidity cannot be obtained, and when the amount is more than 100 parts by weight, flexibility is impaired and sufficient sealing property tends not to be exhibited.

In the present invention, the hydrosilyl group-containing compound (D) is used as the crosslinking agent for the component (A). Although there is no restriction | limiting in particular in the hydrosilyl group containing compound which can be used, Hydrosilyl group containing polysiloxane is preferable and various things can be used. Among them, a hydrosilyl group-containing polysiloxane having 3 or more hydrosilyl groups and 3 to 500 siloxane units is preferable, and a polysiloxane having 3 or more hydrosilyl groups and 10 to 200 siloxane units. More preferred are polysiloxanes having 3 or more hydrosilyl groups and 20 to 100 siloxane units. If the number of hydrosilyl groups is less than 3, sufficient growth of the network due to crosslinking tends not to be achieved and optimal rubber elasticity tends not to be obtained. If the number of siloxane units exceeds 500, the viscosity of the polysiloxane is high (A) There is a tendency that the dispersibility in the component is lowered and the progress of the crosslinking reaction becomes insufficient. The polysiloxane unit mentioned here refers to the following general formulas (I), (II), and (III).
[Si (R ¹ ) ₂ O] (I)
[Si (H) (R ² ) O] (II)
[Si (R ² ) (R ³ ) O] (III)
As the hydrosilyl group-containing polysiloxane, a linear polysiloxane represented by the general formula (IV) or (V);
_{^{R 1 3 SiO- [Si (R}} 1) 2 O] a- [Si (H) (R 2) O] b- [Si (R 2) (R 3) O] c-SiR 1 3 (IV)
_{^{HR 1 2 SiO- [Si (R}} 1) 2 O] a- [Si (H) (R 2) O] b- [Si (R 2) (R 3) O] c-SiR 1 2 H (V)
(In the formula, R ¹ and R ² represent an alkyl group having 1 to 6 carbon atoms or a phenyl group, R ³ represents an alkyl group having 1 to 10 carbon atoms or an aralkyl group. B represents 3 ≦ b, a, b. , C represents an integer satisfying 3 ≦ a + b + c ≦ 500.)
A cyclic siloxane represented by the general formula (VI);

(In the formula, R ⁴ and R ⁵ represent an alkyl group having 1 to 6 carbon atoms or a phenyl group, R ⁶ represents an alkyl group having 1 to 10 carbon atoms or an aralkyl group. E represents 3 ≦ e, d, e , F represents an integer satisfying d + e + f ≦ 500.) And the like can be used.

  The hydrosilyl group-containing compound is preferably either polymethylhydrogensiloxane or a copolymer of dimethylsiloxane and methylhydrogensiloxane from the viewpoints of reactivity and viscosity.

  The compounding quantity of a hydrosilyl group containing compound (D) is 0.1-10 weight part with respect to 100 weight part of (A) component. When the amount is less than 0.1 parts by weight, crosslinking tends to be insufficient. When the amount exceeds 10 parts by weight, a large amount of active hydrosilyl groups remain even after crosslinking, so that volatile matter tends to be generated. .

  The crosslinking reaction of the component (A) and the component (D) proceeds by mixing and heating the two components, but it is preferable to add a hydrosilylation catalyst in order to advance the reaction more rapidly. Such hydrosilylation catalyst is not particularly limited, and examples thereof include radical generators such as organic peroxides and azo compounds, and transition metal catalysts.

  The radical generator is not particularly limited, and examples thereof include di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di ( t-butylperoxy) -3-hexyne, dicumyl peroxide, t-butylcumyl peroxide, dialkyl peroxides such as α, α′-bis (t-butylperoxy) isopropylbenzene, benzoyl peroxide, p-chlorobenzoyl peroxide, m-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, diacyl peroxides such as lauroyl peroxide, peracid esters such as t-butyl perbenzoate, diisopropyl percarbonate, di-2-ethylhexyl percarbonate Peroxydicarbonate such as 1,1 Examples thereof include peroxyketals such as -di (t-butylperoxy) cyclohexane and 1,1-di (t-butylperoxy) -3,3,5-trimethylcyclohexane.

  Also, it is not particularly limited as a transition metal catalyst, for example, platinum simple substance, alumina, silica, carbon black or the like dispersed in a platinum solid, chloroplatinic acid, chloroplatinic acid and alcohol, aldehyde, ketone, etc. And a platinum-olefin complex and a platinum (0) -dialkenyltetramethyldisiloxane complex. Examples of catalysts other than platinum compounds include RhCl (PPh3) 3, RhCl3, RuCl3, IrCl3, FeCl3, AlCl3, PdCl2, H2O, NiCl2, TiCl4 and the like. These catalysts may be used alone or in combination of two or more. Of these, platinum vinylsiloxane is most preferred in terms of crosslinking efficiency.

Although there is no restriction | limiting in particular as a catalyst amount, It is good to use in the range of 10 ^{< -1} > ^-10 <^-8> mol with respect to 1 mol of crosslinkable functional groups of (A) component, Preferably it is 10 ^<-3 > ^-10 <^-6> mol. It is good to use in the range. When the amount is less than 10 ^-8 mol, the progress of crosslinking tends to be insufficient, and when the amount exceeds 10 ^-1 mol, there is a tendency that heat generation is intense and the crosslinking reaction cannot be sufficiently controlled.

  In the present invention, for the purpose of improving mechanical properties and coring properties without impairing gas barrier properties, as a component (E), the polymer block (a) mainly comprising an aromatic vinyl compound and isobutylene are mainly used. A block copolymer comprising the polymer block (b) to be added can be added.

  The polymer block (a) mainly composed of an aromatic vinyl compound is a polymer block composed of 60% by weight or more, preferably 80% by weight or more of units derived from an aromatic vinyl compound.

  Aromatic vinyl compounds include styrene, o-, m- or p-methylstyrene, α-methylstyrene, β-methylstyrene, 2,6-dimethylstyrene, 2,4-dimethylstyrene, α-methyl-o. -Methylstyrene, α-methyl-m-methylstyrene, α-methyl-p-methylstyrene, β-methyl-o-methylstyrene, β-methyl-m-methylstyrene, β-methyl-p-methylstyrene, 2 , 4,6-trimethylstyrene, α-methyl-2,6-dimethylstyrene, α-methyl-2,4-dimethylstyrene, β-methyl-2,6-dimethylstyrene, β-methyl-2,4-dimethyl Styrene, o-, m- or p-chlorostyrene, 2,6-dichlorostyrene, 2,4-dichlorostyrene, α-chloro-o-chlorostyrene, α-chloro-m- Chlorostyrene, α-chloro-p-chlorostyrene, β-chloro-o-chlorostyrene, β-chloro-m-chlorostyrene, β-chloro-p-chlorostyrene, 2,4,6-trichlorostyrene, α- Chloro-2,6-dichlorostyrene, α-chloro-2,4-dichlorostyrene, β-chloro-2,6-dichlorostyrene, β-chloro-2,4-dichlorostyrene, o-, m- or p- t-butylstyrene, o-, m- or p-methoxystyrene, o-, m- or p-chloromethylstyrene, o-, m- or p-bromomethylstyrene, styrene derivatives substituted with silyl groups, indene And vinyl naphthalene. Among these, styrene, α-methylstyrene, and a mixture thereof are preferable from the viewpoint of industrial availability and glass transition temperature.

  The polymer block (b) mainly composed of isobutylene is a polymer block composed of 60% by weight or more, preferably 80% by weight or more of units derived from isobutylene.

  In any of the polymer blocks (a) and (b), a mutual monomer can be used as a copolymerization component, and other cationically polymerizable monomer components can be used. Examples of such a monomer component include monomers such as aliphatic olefins, dienes, vinyl ethers, silanes, vinyl carbazole, β-pinene, and acenaphthylene. These can be used alone or in combination of two or more.

  Aliphatic olefin monomers include ethylene, propylene, 1-butene, 2-methyl-1-butene, 3-methyl-1-butene, pentene, hexene, cyclohexene, 4-methyl-1-pentene, vinylcyclohexane Octene, norbornene and the like.

  Examples of the diene monomer include butadiene, isoprene, hexadiene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, divinylbenzene, and ethylidene norbornene.

  Examples of the vinyl ether monomer include methyl vinyl ether, ethyl vinyl ether, (n-, iso) propyl vinyl ether, (n-, sec-, tert-, iso) butyl vinyl ether, methyl propenyl ether, ethyl propenyl ether and the like.

  Examples of the silane compound include vinyltrichlorosilane, vinylmethyldichlorosilane, vinyldimethylchlorosilane, vinyldimethylmethoxysilane, vinyltrimethylsilane, divinyldichlorosilane, divinyldimethoxysilane, divinyldimethylsilane, 1,3-divinyl-1,1,3. , 3-tetramethyldisiloxane, trivinylmethylsilane, γ-methacryloyloxypropyltrimethoxysilane, γ-methacryloyloxypropylmethyldimethoxysilane, and the like.

  As long as (E) component of this invention is comprised from (a) block and (b) block, there is no restriction | limiting in particular in the structure, For example, linear, branched, star-like structures, etc. Any of a block copolymer, a diblock copolymer, a triblock copolymer, a multiblock copolymer, and the like having a cation can be selected. A preferable structure includes a triblock copolymer composed of (a)-(b)-(a) from the viewpoint of physical property balance and molding processability. These may be used alone or in combination of two or more in order to obtain desired physical properties and moldability.

  The ratio of the block (a) to the block (b) is not particularly limited, but from the viewpoint of flexibility and rubber elasticity, the content of the block (a) in the component (E) is 5 to 50% by weight. Is preferable, and it is further more preferable that it is 10 to 40 weight%.

  The molecular weight of the component (E) is not particularly limited, but is preferably 30,000 to 500,000 in terms of weight average molecular weight by GPC measurement from the viewpoints of fluidity, molding processability, rubber elasticity, and the like. 000 to 300,000 is particularly preferable. When the weight average molecular weight is lower than 30,000, mechanical properties tend not to be sufficiently exhibited, whereas when it exceeds 500,000, fluidity and workability tend to deteriorate.

Although there is no restriction | limiting in particular about the manufacturing method of (E) component, For example, it can obtain by polymerizing a monomer component in presence of the compound represented by the following general formula (VII).
(CR ⁷ R ⁸ X) nR ⁹ (VII)
[Wherein X is a halogen atom, a substituent selected from an alkoxy group having 1 to 6 carbon atoms or an acyloxy group, R ⁷ and R ⁸ are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, and R ⁷ and R ⁸ May be the same or different, R ⁹ represents a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group, and n represents a natural number of 1 to 6. ]

  The compound represented by the general formula (VII) serves as an initiator and generates a carbon cation in the presence of a Lewis acid or the like, and is considered to be a starting point for cationic polymerization. Examples of the compound of the general formula (VII) used in the present invention include the following compounds.

(1-Chloro-1-methylethyl) benzene [C ₆ H ₅ C (CH ₃ ) ₂ Cl], 1,4-bis (1-chloro-1-methylethyl) benzene [1,4-Cl (CH ₃ ) ₂ CC ₆ H ₄ C (CH ₃ ) ₂ Cl], 1,3-bis (1-chloro-1-methylethyl) benzene [1,3-Cl (CH ₃ ) ₂ CC ₆ H ₄ C (CH ₃ ) ₂ Cl], 1,3,5-tris (1-chloro-1-methylethyl) benzene [1,3,5- (ClC (CH ₃ ) ₂ ) ₃ C ₆ H ₃ ], 1,3-bis (1-Chloro-1-methylethyl) -5- (tert-butyl) benzene [1,3- (C (CH ₃ ) ₂ Cl) 2-5- (C (CH ₃ ) ₃ ) C ₆ H ₃ ]

Among these, bis (1-chloro-1-methylethyl) benzene [C ₆ H ₄ (C (CH ₃ ) ₂ Cl) ₂ ] is particularly preferable. [Bis (1-chloro-1-methylethyl) benzene is also called bis (α-chloroisopropyl) benzene, bis (2-chloro-2-propyl) benzene or dicumyl chloride, and tris (1-chloro- 1-methylethyl) benzene is also referred to as tris (α-chloroisopropyl) benzene, tris (2-chloro-2-propyl) benzene, or tricumyl chloride.

When the component (E) is produced, a Lewis acid catalyst can also coexist. Such Lewis acid may be any one that can be used for cationic polymerization. TiCl ₄ , TiBr ₄ , BCl ₃ , BF ₃ , BF ₃ .OEt ₂ , SnCl ₄ , SbCl ₅ , SbF ₅ , WCl ₆ , TaCl ₅ , VCl ₅ , FeCl ₃ , ZnBr ₂ , AlCl ₃ , AlBr _3, etc .; metal halides such as Et ₂ AlCl, EtAlCl _2, etc. can be preferably used. Of these, TiCl ₄ , BCl ₃ , and SnCl ₄ are preferable in view of the ability as a catalyst and industrial availability. The amount of Lewis acid used is not particularly limited, but can be set in view of the polymerization characteristics or polymerization concentration of the monomer used. Usually, it is 0.1-100 mol equivalent with respect to the compound represented by general formula (VII), Preferably it is the range of 1-50 mol equivalent.

  In the production of the component (E), an electron donor component can be allowed to coexist if necessary. This electron donor component is believed to have the effect of stabilizing the growth carbon cation during cationic polymerization, and the addition of an electron donor produces a polymer with a narrow molecular weight distribution and a controlled structure. be able to. The electron donor component that can be used is not particularly limited, and examples thereof include pyridines, amines, amides, sulfoxides, esters, and metal compounds having an oxygen atom bonded to a metal atom.

  The polymerization of the component (E) can be carried out in an organic solvent as necessary, and the organic solvent can be used without particular limitation as long as it does not substantially inhibit cationic polymerization. Specifically, halogenated hydrocarbons such as methyl chloride, dichloromethane, chloroform, ethyl chloride, dichloroethane, n-propyl chloride, n-butyl chloride, chlorobenzene; benzene, toluene, xylene, ethylbenzene, propylbenzene, butylbenzene, etc. Alkylbenzenes; linear aliphatic hydrocarbons such as ethane, propane, butane, pentane, hexane, heptane, octane, nonane, decane; 2-methylpropane, 2-methylbutane, 2,3,3-trimethylpentane, 2 Branched aliphatic hydrocarbons such as 1,2,5-trimethylhexane; cycloaliphatic hydrocarbons such as cyclohexane, methylcyclohexane and ethylcyclohexane; paraffin oil obtained by hydrorefining petroleum fractions, etc. .

  These solvents can be used alone or in combination of two or more in consideration of the balance of the polymerization characteristics of the monomer constituting the component (E) and the solubility of the resulting polymer.

  The amount of the solvent used is determined so that the concentration of the polymer is 1 to 50 wt%, preferably 5 to 35 wt%, in consideration of the viscosity of the resulting polymer solution and the ease of heat removal.

  In carrying out the actual polymerization, each component is mixed at a temperature of, for example, −100 ° C. or more and less than 0 ° C. under cooling. In order to balance the energy cost and the stability of polymerization, a particularly preferred temperature range is −30 ° C. to −80 ° C.

  (E) It is preferable to mix 1-50 weight part with respect to 100 weight part of (A) component, and it is more preferable to mix 1-30 weight part. If it exceeds 50 parts by weight, the heat distortion resistance tends to deteriorate.

  In the present invention, the component (A) is dynamically crosslinked by the component (D) during melt kneading in the presence of the components (B) and (C). The temperature for melt kneading is preferably 130 to 240 ° C. If the temperature is lower than 130 ° C., the component (C) is not sufficiently melted and kneading tends to be uneven. At a temperature higher than 240 ° C., thermal decomposition of the component (A) tends to occur. In this dynamic crosslinking step, components (A), (B), and (C) are essential, but crosslinking may be performed after adding other components such as component (E) as appropriate. However, since some other components inhibit the crosslinking reaction, it is preferable to add the components after crosslinking. There is no restriction | limiting in particular as a method for melt-kneading, A well-known method is applicable. For example, (A), (B), (C) component, and further, a cross-linking agent, a cross-linking catalyst, and other components to be blended in order to obtain predetermined physical properties are mixed with a heating kneader, such as a single screw extruder, twin screw, etc. It can be produced by melt-kneading using an extruder, roll, Banbury mixer, Brabender, kneader, high shear mixer or the like. Further, as the order of addition, after the (C) component is melted, the (A) component and the (B) component are added, and if necessary, other components are added and mixed uniformly, and then the crosslinking agent and A method in which a crosslinking catalyst is added to advance the crosslinking reaction is preferred.

  In addition, other thermoplastic resins, thermoplastic elastomers, rubbers, and the like can be added to the rubber plug composition of the present invention as long as the performance is not impaired. As thermoplastic resins, polystyrene, acrylonitrile-styrene copolymer, polymethyl methacrylate, polyvinyl chloride, ABS, MBS, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyphenylene ether, polysulfone, polyamideimide, polyetherimide Etc. Examples of thermoplastic elastomers include styrene elastomers, olefin elastomers, vinyl chloride elastomers, urethane elastomers, ester elastomers, and nylon elastomers. Furthermore, examples of the rubber include butyl rubber, natural rubber, butadiene rubber, isoprene rubber, styrene butadiene rubber (SBR), acrylonitrile butadiene rubber (NBR), acrylic rubber, and silicone rubber. Among these, when the component (E) is used, polyphenylene ether is preferably used for the purpose of improving its heat resistance. For the purpose of adjusting moldability and slidability, hydrogenated styrene elastomers such as SEBS and SEPS are also preferably used.

  Further, for the purpose of improving the molding fluidity, a petroleum hydrocarbon resin can be added as necessary. The petroleum hydrocarbon resin is a resin having a molecular weight of about 300 to 10000 using petroleum unsaturated hydrocarbon as a direct raw material, for example, an aliphatic petroleum resin, an alicyclic petroleum resin and a hydride thereof, an aromatic resin. Petroleum resin and hydride thereof, aliphatic aromatic copolymer petroleum resin and hydride thereof, dicyclopentadiene petroleum resin and hydride thereof, low molecular weight polymer of styrene or substituted styrene, coumarone / indene resin, etc. . Among these, alicyclic saturated hydrocarbon resins are preferable from the viewpoint of compatibility with the component (A).

  Furthermore, a filler can be blended in the rubber plug composition of the present invention from the viewpoint of improving physical properties or economic merit. Suitable fillers include clay, diatomaceous earth, silica, talc, barium sulfate, calcium carbonate, magnesium carbonate, metal oxide, mica, graphite, aluminum hydroxide and other flaky inorganic fillers, various metal powders, wood chips Examples thereof include glass powder, ceramic powder, carbon black, granular or powdered solid filler such as granular or powdered polymer, and other various natural or artificial short fibers and long fibers. Moreover, weight reduction can be attained by mix | blending the hollow filler, for example, inorganic hollow fillers, such as a glass balloon and a silica balloon, and the organic hollow filler which consists of a polyvinylidene fluoride and a polyvinylidene fluoride copolymer. Furthermore, various foaming agents can be mixed in order to improve various physical properties such as weight reduction and impact absorption, and it is also possible to mix gas mechanically during mixing. Among these, talc is preferable from the viewpoint of economy and hygiene.

  The blending amount of the filler is preferably 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, and further preferably 1 to 30 parts by weight with respect to 100 parts by weight of the component (A). preferable. If it exceeds 100 parts by weight, the flexibility of the resulting composition tends to be impaired, which is not preferable.

  Moreover, antioxidant and a ultraviolet absorber can be mixed with the composition for rubber stoppers of this invention as needed. The mixing amount is preferably 0.01 to 10 parts by weight and more preferably 0.01 to 5 parts by weight with respect to 100 parts by weight of component (A). In addition, flame retardants, antibacterial agents, light stabilizers, colorants, fluidity improvers, antiblocking agents, antistatic agents, etc. can be added as other additives, each of which can be used alone or in combination of two or more. Can be used. In particular, when the hardness is low, blocking is likely to occur when granulation (pelletization) is performed after melt-kneading, so the addition of an anti-blocking agent is effective. As such an antiblocking agent, polypropylene powder, polyethylene powder, ultrahigh molecular weight polyethylene powder, or the like can be used.

  The thermoplastic elastomer of the present invention can be used for medical rubber stoppers and medical packings.

  In producing the rubber plug and packing of the present invention, although not particularly limited, various molding methods and molding apparatuses generally used are used depending on the type, application, and shape of the target rubber plug. Any molding method such as injection molding, extrusion molding, press molding, blow molding, calender molding, cast molding, etc. is exemplified, and these methods may be combined. Among these, injection molding is the most preferable method in terms of mass productivity and production efficiency, and since the composition of the present invention is thermoplastic, it is possible to reuse runners and sprues. As conditions for injection molding, it is preferable to set the resin temperature in a range of 170 ° C. to 250 ° C., and not only a cold runner mold but also a hot runner mold can be preferably used.

  Moreover, the rubber plug and packing containing the thermoplastic elastomer of the present invention can be used by laminating the surface with a fluororesin or a polyethylene resin.

  Furthermore, the rubber stopper containing the thermoplastic elastomer of the present invention can be used by applying a lubricant such as silicone oil for the purpose of improving the sliding property with a vial or a syringe.

  Examples of the rubber plug used that contains the thermoplastic elastomer of the present invention include injection containers such as vials and prefilled syringes, stoppers such as vacuum blood collection tubes, and gaskets.

  Hereinafter, the present invention will be described more specifically with reference to examples. In addition, this invention is not limited at all by these Examples, In the range which does not change the summary, it can change suitably.

  The molecular weight, terminal allyl group, and styrene content of the components (A) and (E) shown in this example, and the physical properties of the rubber plug composition and the rubber plug were measured by the following methods.

(Molecular weight)
A GPC system manufactured by Waters (column: Shodex K-804 (polystyrene gel) manufactured by Showa Denko KK, mobile phase: chloroform) was used, and the weight average molecular weight was converted to polystyrene.

(Number of terminal allyl groups)
The number of terminal allyl groups per molecule was measured by dissolving polyisobutylene in deuterated chloroform, measuring ¹ H-NMR, and determining the ratio of allyl groups to initiator.

(Styrene content)
The block copolymer was dissolved in deuterated chloroform and ¹ H-NMR was measured. From the ratio of the isobutylene-derived peak (8H) and the styrene-derived aromatic ring peak (5H), the molar fraction of styrene was determined. The styrene content (% by weight) was calculated by converting the molecular weight per unit into a weight fraction.

(Melt viscosity)
In accordance with JIS K 7199, the melt viscosity (poise) was measured under the conditions of 200 ° C. and shear rate = 1216 / s.

(hardness)
In accordance with JIS K-6253, three 2 mm thick press sheets were stacked, and the hardness (hereinafter abbreviated as JIS-A hardness) was measured with a spring type A durometer.

(Compression set)
In accordance with JIS K-6262, a 12.0 mm thick press sheet was used as a test piece. The measurement was carried out under the conditions of 70 ° C. × 22 hours and 25% deformation.

(Gas barrier properties)
Based on JIS K-7126, the permeability coefficient of oxygen was measured. As a test piece, a 1 mm thick press sheet was used, and a differential pressure method (A method) was used.

(Heat-resistant deformation)
An ISO 8362-2 A-type rubber plug (flange diameter 20 mm) was heated with a pressure cooker (PC-305S manufactured by Hirayama Seisakusho Co., Ltd.) set at 121 ° C., and then visually checked for deformation. The water vapor pressure is a saturated vapor pressure at 121 ° C. The case where there was no deformation was indicated by ◯, the case where the flange portion had a beveled curve was indicated by Δ, and the case where the entire portion was deformed was indicated by ×. If there is even a slight deformation, the sealing performance may not be maintained, so Δ and × cannot be used as a rubber stopper.

(Water elution)
In accordance with the Japanese Pharmacopoeia rubber plug test method for infusion, measurements were made as follows. All items must conform to the standard.

Preparation of the test solution;
After washing the 2mm-thick press sheet with water, it is dried at room temperature, put in a glass container, accurately adding 10 times the sample weight of water, and plugged appropriately, then in an autoclave heated to 121 ° C. After heating for 1 hour, the hard glass container was taken out and allowed to stand at room temperature, the sheet was quickly removed, and this liquid was used as a test liquid. Separately, a blank test solution was prepared in the same manner without water and without a press sheet.

Transmittance;
Using the blank test solution as a control, the transmittance at wavelengths of 430 nm and 650 nm was measured at a layer length of 10 mm. If the transmittance is 99.0% or more, it conforms to the standard. Units%.

pH;
20 ml each of the test solution and the blank test solution were taken, and 1.0 ml of a solution obtained by dissolving 1.0 g of potassium chloride in water to 1000 ml was added, and the pH of both solutions was measured. If the difference in pH between the two solutions is 1.0 or less, it conforms to the standard.

Potassium permanganate reducing substance;
Take 100 ml of the test solution in a stoppered Erlenmeyer flask, add 10.0 ml of 0.01N potassium permanganate solution and 5 ml of dilute sulfuric acid, boil for 3 minutes, cool, and add 0.10 g of potassium iodide to this and seal tightly. The mixture was shaken and allowed to stand for 10 minutes, and then titrated with 0.01N sodium thiosulfate (indicator; 5 drops of starch test solution). Separately, 100 ml of blank test solution was used and operated simultaneously. The difference in consumption of 0.01 N potassium permanganate solution was measured. If the difference in consumption of 0.01 N potassium permanganate solution is 2.0 ml or less, it conforms to the standard. The unit is ml.

Evaporation residue;
100 ml of the test solution was taken and evaporated to dryness on a water bath, the residue was dried at 105 ° C. for 1 hour, and the weight of the residue was measured. If the residue is 2.0 mg or less, it conforms to the standard. The unit is mg.

UV absorption;
The test solution was tested by the absorbance measurement method using the blank test solution as a control. If the absorbance at a wavelength of 220 to 350 nm is 0.20 or less, it conforms to the standard.

(Alcohol elution)
After washing 5 g of a 2 mm thick press sheet with water, it is dried at room temperature, placed in a glass container, 100 ml of isopropanol is added accurately, refluxed for 2 hours, and then the hard glass container is taken out and left to reach room temperature. The sheet was quickly removed and this solution was used as a test solution. GC / MS analysis was performed using 1 μL of the test solution.
GC / MS-5993N manufactured by Agilent Technologies was used, and the carrier gas was measured at 1 ml / min of helium.
The number of peaks with an abundance of 100,000 or more was calculated.
A thermoplastic elastomer was produced using the following raw materials.
Ingredient (A) Polyisobutylene having an allyl group at the terminal, produced in the following Production Example 1 (hereinafter abbreviated as APIB)
Component (B) Polyisobutylene having no crosslinkable functional group TETRAX4T: Weight average molecular weight 58,000 Polyisobutylene (manufactured by Shin Nippon Chemical Co., Ltd.)
Component (C) Polyolefin resin Polypropylene (homotype): Mitsui Polypro J108M (MFR: 45 g / 10 min, hereinafter abbreviated as HPP) manufactured by Mitsui Chemicals, Inc.
Component (D) Hydrosilyl group-containing compound (crosslinking agent)
Hydrosilyl group-containing polysiloxane Polysiloxane represented by the following chemical formula (hereinafter abbreviated as H-oil)
_{(CH 3) 3 SiO- [Si} (H) (CH 3) O] 48 -Si (CH 3) 3
Cross-linking catalyst 1,1,3,3-tetramethyl-1,3-dialkenyldisiloxane complex of zerovalent platinum, 3 wt% xylene solution (hereinafter abbreviated as Pt catalyst)
Component (E) Isobutylene block copolymer (hereinafter abbreviated as SIBS)
Softening agent produced in the following Production Example 2 Polyisobutylene oil: Idemitsu Polybutene 100R (hereinafter abbreviated as 100R) manufactured by Idemitsu Kosan Co., Ltd. Weight average molecular weight 1000
Polyisobutylene: BASF Corporation Opanol B50SF Weight average molecular weight 220,000 (hereinafter abbreviated as HMPIB)
Paraffinic oil: Diana Process PW-90 (hereinafter abbreviated as PW90) manufactured by Idemitsu Kosan Co., Ltd. Weight average molecular weight 500
Other Hydrogenated Styrene-Butadiene Block Copolymer: Kraton Polymer Japan Co., Ltd. Kraton G1650 (styrene content 29%, hereinafter abbreviated as SEBS)
Butyl dynamic crosslinked elastomer: Trefsin 3271-65W308 (hereinafter abbreviated as TREF) manufactured by AES Japan.

(Production Example 1) (A) Isobutylene copolymer having an allyl group at the terminal A three-way cock, a thermocouple, and a stirring seal were attached to a 2 L separable flask, and nitrogen substitution was performed. After nitrogen substitution, nitrogen was flowed using a three-way cock. To this, 785 ml of toluene and 265 ml of ethylcyclohexane were added using a syringe and cooled to about -70 ° C. After cooling, 277 ml (2933 mmol) of isobutylene monomer was added. After cooling to about −70 ° C. again, 0.85 g (3.7 mmol) of p-dicumyl chloride and 0.68 g (7.4 mmol) of picoline were dissolved in 10 ml of toluene and added. When the internal temperature of the reaction system became -74 ° C and stabilized, 19.3 ml (175.6 mmol) of titanium tetrachloride was added to initiate polymerization. When the polymerization reaction was completed (90 minutes), 1.68 g (11.0 mmol) of a 75% -allyltrimethylsilane / toluene solution was added, and the mixture was further reacted for 2 hours. Then, it deactivated with the pure water heated at about 50 degreeC, Furthermore, the organic layer was wash | cleaned 3 times with pure water (70 to 80 degreeC), the organic solvent was removed at 80 degreeC under pressure reduction, and APIB was obtained. The weight average molecular weight by GPC measurement was 50000, and the number of terminal allyl groups determined by ¹ H-NMR was 2.0 / mol.

(Production Example 2) (E) Isobutylene block copolymer, triblock structure having a styrene content of 15% After the inside of a polymerization vessel of a 500 mL separable flask was purged with nitrogen, n-hexane (with molecular sieves) was used with a syringe. 21.2 mL of dried product) and 256.6 mL of butyl chloride (dried with molecular sieves) were added, and the polymerization vessel was placed in a -70 ° C. dry ice / methanol bath and cooled, and then 60.5 mL of isobutylene monomer was contained. A Teflon (registered trademark) feeding tube was connected to the pressure-resistant glass-made liquefied sampling tube with a three-way cock, and isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. 0.120 g of p-dicumyl chloride and 0.121 g of N, N-dimethylacetamide were added. Next, 1.02 mL of titanium tetrachloride was further added to initiate polymerization. After stirring for 75 minutes from the start of polymerization, 8.02 g of styrene monomer was subsequently added into the polymerization vessel. 75 minutes after adding the mixed solution, the reaction was terminated by adding a large amount of water.

The reaction solution was washed twice with water, the solvent was evaporated, and the resulting polymer was vacuum-dried at 60 ° C. for 24 hours to obtain the desired block copolymer. When the molecular weight was measured by a gel permeation chromatography (GPC) method, the weight average molecular weight was 130,000. The styrene content calculated by ¹ H-NMR was 15 wt%.

  (Example 1) APIB ((A) component), PIB ((B) component), and HPP ((C) component) obtained in Production Example 1 were blended in the proportions shown in Table 1 and set to 170 ° C. The lab plast mill (Toyo Seiki Seisakusho Co., Ltd.) was melt-kneaded for 2 minutes, and the hydrosilyl group-containing compound H-oil was added in the ratio shown in Table 1 and kneaded for 1 minute. The Pt catalyst was added at the ratio shown in Table 1, and further melt-kneaded until the crosslinking proceeded and the torque value reached the maximum value. After kneading for 3 minutes after the torque value reached the maximum value, the dynamic cross-linking composition was taken out. The obtained thermoplastic elastomer composition could be easily formed into a sheet shape at 200 ° C. with a heating press (manufactured by Shindo Metal Industry Co., Ltd.). The obtained sheet was measured for hardness, melt viscosity, compression set, heat distortion resistance, gas permeability coefficient, coring, water elution, and alcohol elution according to the above methods. Table 1 shows the physical properties of each sheet.

  Example 2 A sheet was obtained in the same manner as in Example 1 except that the blending amounts of the components (A), (B), and (C) were changed to the ratios shown in Table 1, and the physical properties were measured.

  Example 3 A sheet was obtained in the same manner as in Example 1 except that the blending amounts of the components (A), (B), and (C) were changed to the ratios shown in Table 1, and the physical properties were measured.

  (Example 4) APIB ((A) component), PIB ((B) component), HPP ((C) component), SIBS ((D) component) were blended in the proportions shown in Table 1, and the temperature was increased to 170 ° C. Melting and kneading for 2 minutes using the set Laboplast mill, adding H-oil, which is a hydrosilyl group-containing compound, in the ratio shown in Table 1, kneading for 1 minute, and Pt catalyst as a crosslinking catalyst in Table 1 The mixture was added at the indicated ratio, and further melt kneaded until the crosslinking proceeded and the torque value reached the maximum value. After kneading for 3 minutes after the torque value reached the maximum value, the dynamic cross-linking composition was taken out. The obtained thermoplastic elastomer composition could be easily formed into a sheet by a hot press at 200 ° C. The obtained sheet was measured for hardness, melt viscosity, compression set, heat distortion resistance, gas permeability coefficient, coring, water elution, and alcohol elution according to the above methods. Table 1 shows the physical properties of each sheet.

(Comparative Example 1)
HPP (component (C)), SEBS, and PW-90 were blended in the proportions shown in Table 2, and melt-kneaded for 10 minutes using a lab plast mill set at 170 ° C. The obtained thermoplastic elastomer composition could be formed into a sheet shape with a hot press at 200 ° C. The obtained sheet was measured for hardness, melt viscosity, compression set, heat distortion resistance, gas permeability coefficient, coring, water elution, and alcohol elution according to the above methods. Table 2 shows the physical properties of each sheet.

(Comparative Example 2)
A sheet was obtained in the same manner as in Comparative Example 1 except that it was melted and kneaded for 10 minutes using a Laboplast mill with SIBS set at 170 ° C. The obtained sheet was measured in the same manner as in Comparative Example 1. Table 2 shows the physical properties of each sheet.

(Comparative Example 3)
A sheet was obtained in the same manner as in Comparative Example 1 except that HPP (component (C)), SIBS (component (E)), and PW-90 were blended in the proportions shown in Table 2. The obtained sheet was measured in the same manner as in Comparative Example 1. Table 2 shows the physical properties of each sheet.

(Comparative Example 4)
A sheet was obtained in the same manner as in Comparative Example 1 except that it was melted and kneaded for 10 minutes using a Laboplast mill with TREF set at 170 ° C. The obtained sheet was measured in the same manner as in Comparative Example 1. Table 2 shows the physical properties of each sheet.

(Comparative Example 5)
APIB (component (A)), HPP (component (C)), SIBS (component (D)) were blended in the proportions shown in Table 2, and melt kneaded for 2 minutes using a lab plast mill set at 170 ° C. Then, H-oil, which is a hydrosilyl group-containing compound, is added in the ratio shown in Table 2, and after kneading for 1 minute, Pt catalyst, which is a crosslinking catalyst, is added in the ratio shown in Table 2, and crosslinking proceeds. Further melt-kneading was performed until the torque value reached the maximum value. After kneading for 3 minutes after the torque value reached the maximum value, the dynamic cross-linking composition was taken out. The obtained thermoplastic elastomer composition could be formed into a sheet shape with a hot press at 200 ° C. The obtained sheet was measured for hardness, melt viscosity, compression set, heat distortion resistance, gas permeability coefficient, coring, water elution, and alcohol elution according to the above methods. Table 2 shows the physical properties of each sheet.

(Comparative Example 6)
A sheet was obtained in the same manner as in Comparative Example 5 except that APIB (component (A)), HPP (component (C)), and 100R were blended in the proportions shown in Table 2. The obtained sheet was measured in the same manner as in Comparative Example 1. Table 2 shows the physical properties of each sheet.

(Comparative Example 7)
A sheet was obtained in the same manner as in Comparative Example 5 except that APIB (component (A)), HPP (component (C)), and HMPIB were blended in the proportions shown in Table 2. The obtained sheet was measured in the same manner as in Comparative Example 1. Table 2 shows the physical properties of each sheet.

(Comparative Example 8)
A sheet was obtained in the same manner as in Comparative Example 5 except that the blending amounts of the components (A), (B), and (C) were changed to the ratios shown in Table 2, and the physical properties were measured. Table 2 shows the physical properties of each sheet.

(Comparative Example 9)
A sheet was obtained in the same manner as in Comparative Example 5 except that the blending amounts of the components (A), (B), and (C) were changed to the ratios shown in Table 2, and the physical properties were measured. Table 2 shows the physical properties of each sheet.

(Comparative Example 10)
A sheet was obtained in the same manner as in Comparative Example 5 except that the blending amounts of the components (A), (B), (C), and (E) were changed to the ratios shown in Table 2, and the physical properties were measured. Table 2 shows the physical properties of each sheet.

(Comparative Example 11)
A sheet was obtained in the same manner as in Comparative Example 5 except that the blending amounts of the components (A), (B), and (C) were changed to the ratios shown in Table 2, and the physical properties were measured. Table 2 shows the physical properties of each sheet.
It can be seen that Examples 1 to 4 have a high hardness of 45 to 46, excellent compression set, 35% or less, and excellent gas barrier properties. Moreover, it turns out that it is excellent also in the coring property required as a rubber stopper, heat-resistant deformation property, and extractability. Comparative Example 1 is mainly composed of SEBS and PW-90 and is inferior in gas barrier properties. Comparative Example 2 with SIBS alone has poor heat distortion resistance, and Comparative Examples 3 and 6 containing 100R and PW-90 have a problem in alcohol extractability. Comparative Example 4 using a conventional vulcanizing agent is incompatible with water extractability. Comparative Examples 5 and 10 have high melt viscosity and poor molding fluidity. In Comparative Examples 7 to 10, compression set, hardness, and coring are not compatible.

  As described above, in the examples of the present invention, the thermoplastic elastomer, which is the object of the present invention, is easy to mold, has excellent sealing properties and gas barrier properties, has low elution into the contents, and has good needle penetration, and A medical rubber stopper using the same has been obtained.

Claims (8)

100 parts by weight of polyisobutylene (A) having a crosslinkable functional group;
10 to 100 parts by weight of polyisobutylene (B) having a weight average molecular weight of 40,000 to 80,000 having no crosslinkable functional group;
10 to 100 parts by weight of a polyolefin resin (C),
Hydrosilyl group-containing compound (D) 0.1 to 10 parts by weight, the a thermoplastic elastomer obtained by dynamically crosslinking the Dressings containing,
A thermoplastic elastomer characterized in that the component (A) is dynamically crosslinked with the component (D) in the components (B) and (C) while being melt-kneaded. The thermoplastic elastomer according to claim 1, wherein the polyisobutylene (A) having a crosslinkable functional group is a polyisobutylene having an allyl group at a terminal. The thermoplastic elastomer according to claim 1 or 2, wherein the polyisobutylene (A) having a crosslinkable functional group has a weight average molecular weight of 40,000 to 80,000. The thermoplastic elastomer according to any one of claims 1 to 3, wherein the polyolefin resin (C) is polypropylene. The thermoplastic elastomer according to any one of claims 1 to 4, wherein the hydrosilyl group-containing compound is either polymethylhydrogensiloxane or a copolymer of dimethylsiloxane and methylhydrogensiloxane. Furthermore, it contains 1 to 50 parts by weight of an isobutylene block copolymer (E) comprising a polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene polymer block (b). The thermoplastic elastomer according to any one of claims 1 to 5. A medical rubber stopper comprising the thermoplastic elastomer according to claim 1. A medical packing comprising the thermoplastic elastomer according to claim 1.