JP2006274056A - Thermoplastic elastomer composition for container lid liner and container lid liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition which has excellent sealability, gas barrier property and abrasion resistance, is well sanitary, and is used for container lid liners, and to provide a container lid liner using the composition. <P>SOLUTION: This thermoplastic elastomer composition for the container lid liners is characterized by comprising the following components (a), (b) and (c). (a) A block copolymer represented by the general formula: [(A-B)<SB>n</SB>] and/or [(A-B)<SB>n</SB>-A] and having a weight-average mol.wt. of 150,000 to 1,000,000, wherein A is a vinyl aromatic hydrocarbon polymer block; B is an elastomeric polymer block which may be hydrogenated; (n) is an integer of 1 to 5. (b) A butenic liquid polymer having a number-average mol.wt. of 700 to 3,000. (c) An olefinic resin. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a composition for a container lid liner that has good sealing properties and gas barrier properties, and excellent wear resistance, and a container lid liner using the composition. In particular, the present invention relates to a styrene-based thermoplastic elastomer composition for a container lid liner that is suitably used in the medical field, the food field, and the like, and a container lid liner using the composition.

  Conventionally, hygienic and relatively inexpensive polyethylene-based resins have been used for lid liners of food containers and beverage containers. A thermoplastic elastomer composition using a hydrogenated styrene-conjugated diene block copolymer rubber that is excellent in flexibility and compression set has also been proposed. For example, a hydrogenated styrene / butadiene block copolymer 10 is proposed. A composition comprising ˜60 wt%, liquid paraffin 20˜80 wt%, and propylene resin 5˜60 wt% can withstand hot sterilization of the contents and heat sterilization after filling and sealing, and heat deformation or heat shrinkage It is said that the leakage caused by can be effectively eliminated (see Patent Document 1). However, since these compositions are gas permeable, materials that are more difficult to oxidize the content liquid are required.

On the other hand, a composition in which a specific polybutene is added to a styrenic thermoplastic elastomer is used for extrusion molding such as a tube as a thermoplastic elastomer having excellent flexibility and the strength of a vulcanized rubber. Since the fluidity as a product is low, it was considered that the composition was not suitable for a lid liner (see Patent Document 2). Further, the oxygen permeability of the composition has never been studied.
Japanese Patent Publication No. 06-088608 Japanese Patent Laid-Open No. Sho 61-218650

  The present invention has been made in view of the above-mentioned present situation, and has an excellent sealing property, gas barrier property, and abrasion resistance, and a sanitary composition for a container lid liner and a container lid liner using the composition. The purpose is to provide.

As a result of intensive studies to solve the above problems, the present inventors have found that a styrene-based thermoplastic elastomer composition containing a specific block copolymer, a butene-based liquid polymer, and an olefin-based resin is excellent as a container lid liner material, The inventors have found that the above problems can be solved, and have reached the present invention.
That is, the gist of the present invention includes the following components (a), (b) and (c), a thermoplastic elastomer composition for a container lid liner, and a container lid liner using the composition: Exist.

(A) a block copolymer represented by the general formula [(AB) _n ] and / or [(AB) _n -A] and having a weight average molecular weight of 150,000 to 1,000,000 (wherein A Represents a polymer block of vinyl aromatic hydrocarbon, B represents an elastomeric polymer block which may be hydrogenated, and n is an integer of 1 to 5.)

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in sealing performance, gas-barrier property, and abrasion resistance, and can provide a sanitary composition for container lid liners, and a container lid liner using the composition.

(1) Component (a)
The thermoplastic elastomer constituting the thermoplastic elastomer composition for a container lid liner of the present invention is a block copolymer represented by the general formula [(AB) _n ] and / or [(AB) _n -A]. Contains a polymer (wherein A represents a polymer block of vinyl aromatic hydrocarbon, B represents an elastomeric polymer block which may be hydrogenated, and n is an integer of 1 to 5). It is essential to do.

In the block copolymer represented by the general formula [(AB) _n ] and / or [(AB) _n -A], the polymer block A which is a polymer block of vinyl aromatic hydrocarbon is heated. The hard segment as a plastic elastomer and the polymer block B which is an elastomer polymer block constitute a soft segment as a thermoplastic elastomer. A typical example of the block copolymer structure is represented by A-B or A-B-A, and the double bond in the elastomeric polymer block B may be partially or completely hydrogenated. Good.

The thermoplastic elastomer composition for the container lid liner of the present invention has the general formula [(AB) _n ].
Or at least one of a block copolymer represented by a block copolymer represented by the general formula [(AB) _n -A]. Although it is essential, in particular, it contains a block copolymer represented by the general formula [(AB) _n -A].
It is preferable in that it is likely to have appropriate rubber elasticity.

Examples of the vinyl aromatic hydrocarbon in the polymer block A of vinyl aromatic hydrocarbon include styrene, α-methyl styrene, o-, m-, p-methyl styrene, 1,3-dimethyl styrene, vinyl naphthalene, and vinyl. Anthracene and the like can be mentioned, and styrene is particularly preferable from the viewpoint of industrial availability.
Further, the monomer constituting the polymer in the elastomeric polymer block B is not limited as long as the polymer exhibits elastomeric properties, but those having a use temperature of Tg or higher are preferable. Moreover, what consists of conjugated dienes is preferable. Examples of the conjugated diene include butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, and among them, butadiene and isoprene are preferable because of high rubber elasticity.

  Therefore, as the block copolymer of the component (a) in the present invention, the polymer block A is a styrene polymer block, the polymer block B is a butadiene polymer block, an isoprene polymer block, and a butadiene- A block copolymer that is any one selected from the group consisting of isoprene copolymer blocks is particularly preferable, and examples thereof include what is called a so-called styrene thermoplastic elastomer. As the butadiene-isoprene copolymer block, those in which butadiene and isoprene are in a weight ratio of 2/8 to 6/4 are preferable.

  As the block copolymer of component (a) in the present invention, the lower limit of the content (weight ratio) of the polymer block A is preferably 10%, more preferably 15%, and more preferably 20%. It is particularly preferable that the upper limit is 50%, more preferably 45%, and particularly preferably 40%. If the content of the polymer block A is too small, mechanical strength, abrasion resistance, heat resistance and the like as a container lid liner tend to be inferior, while if too large, flexibility as a container lid liner, rubber elasticity, While sealing property etc. are inferior, the butene type liquid polymer of the component (b) mentioned later tends to bleed.

When the monomer constituting the polymer block B is only butadiene, the lower limit of the proportion (weight ratio) of 1,2-bonds of butadiene is 20 in view of maintaining rubber elasticity as a container lid liner. %, Particularly preferably 25%, an upper limit of 50% is preferred, and 45% is particularly preferred.
The block copolymer of component (a) in the present invention is preferably a hydrogenated block copolymer obtained by hydrogenating the block copolymer, and in that case, the double copolymer in the polymer block B The hydrogenation rate of the bond is preferably 30% or more, more preferably 50% or more, and particularly preferably 90% or more. When the hydrogenation rate is increased, the container lid liner tends to improve heat resistance, weather resistance, wear resistance, and the like.

  In the present invention, the block copolymer of the component (a) in the thermoplastic elastomer constituting the tubular body has a weight average molecular weight of 150,000 to as a polystyrene equivalent value measured by gel permeation chromatography (GPC). 1 million is essential, the lower limit is preferably 180,000, particularly preferably 200,000, the upper limit is preferably 700,000, and particularly preferably 500,000. If the weight average molecular weight is too small, the rubber elasticity, mechanical strength and molding processability of the thermoplastic elastomer composition for container lid liners tend to be reduced, and the butene-based liquid polymer of component (b) described later However, if it is too large, problems such as difficulty in molding as a thermoplastic elastomer composition for a container lid liner are likely to occur.

In the general formula [(AB) _n ] and the general formula [(AB) _n -A], each n independently represents an integer of 1 to 5, and the general formula [(AB) _n ] And a block copolymer represented by [(A-
B) _n may be different when both of the block copolymers represented by _n- A] are contained (example: [(AB) ₂ ] and general formula [(AB) ₃ -A] and the like, and n is preferably 1 from the viewpoint of easy synthesis. When n is 2 or more in the general formula [(AB) _n ], the plurality of polymer blocks A and B may be different from each other (for example, [A ₁ -B ₁ -A _{2- B 2], [a-B} 1 -A-B 2], [a 1 -B-a 2 -B] , etc.), because people are the same is easy synthesis preferable. Similarly, when there are a plurality of polymer blocks A and B in the general formula [(AB) _n -A], the polymer blocks A and B may be different, but the same one is synthesized. It is preferable because it is easy. Furthermore, each of the general formula [(AB) _n ] and the general formula [(AB) _n -A] may contain a plurality of types of copolymer blocks (example: [(A ₁ -B _{1) n]} and _{[(a 2 -B 2) n} ], [(a 1 -B 1) n -A 1] and _{[(a 2 -B 2) n} -A 2] , etc.), the same Is preferred because it is easy to synthesize. In addition, when both a block copolymer represented by the general formula [(AB) _n ] and a block copolymer represented by [(AB) _n -A] are included, both block copolymers The polymer blocks A and B in the polymer may be different from each other (eg, [(A ₁ -B ₁ ) _n ] and [(A ₂ -B ₂ ) _n -A ₂ ] etc.), but they are the same. Is preferred because it is easy to synthesize.

  The block copolymer in the present invention may be produced by any method as long as it has the structure and physical properties described above. For example, the method described in Japanese Patent Publication No. 40-23798, that is, a method of performing block copolymerization in an inert solvent in the presence of a lithium catalyst can be employed. It can also be obtained by polymerizing styrene or a derivative thereof and an elastomeric block and coupling it with a coupling agent. In addition to these, an elastomeric block can be polymerized using a dilithium compound as an initiator, and then styrene or a derivative thereof can be polymerized sequentially.

Examples of the hydrogenation treatment in the case where the block copolymer is hydrogenated include, for example, JP-B-42-8704, JP-B-43-6636, JP-A-59-133203, JP-A-60-79005. Can be carried out in an inert solvent in the presence of a hydrogenation catalyst.
These block copolymers are commercially available, for example, as “KRATON-G” manufactured by Kraton Polymer, “Septon” manufactured by Kuraray, and “Tuftec” manufactured by Asahi Kasei.

(2) Component (b)
The thermoplastic elastomer constituting the thermoplastic elastomer composition for a container lid liner of the present invention must contain a butene liquid polymer.
Examples of the butene-based liquid polymer include homopolymers such as 1-butene, 2-butene, and isobutene, and copolymers having these as a main component. Among them, for the reason that oxygen permeability is good. A homopolymer of isobutene or a copolymer of 1-butene and / or 2-butene containing isobutene as a main component is preferable.

  The butene-based liquid polymer must have a lower limit of number average molecular weight measured by gel permeation chromatography (GPC) of 700, preferably 800, and an upper limit of 3,000. And preferably 2,500. If the number average molecular weight is too small, the low molecular weight component bleeds and the surface of the container lid liner tends to be sticky. On the other hand, if the number average molecular weight is too large, it is difficult to uniformly disperse the component (a) in the block copolymer. .

  In the present invention, the butene-based liquid polymer preferably has a lower kinematic viscosity at 40 ° C. of 2,000 cSt, particularly preferably 5,000, and an upper limit of 200,000 cSt. Is preferred, with 100,000 cSt being particularly preferred. Further, the lower limit of the pour point is preferably −40 ° C., more preferably −30 ° C., the upper limit is preferably 10 ° C., and further preferably 5 ° C. The lower limit of the flash point (COC) is preferably 180 ° C., particularly preferably 200 ° C., the upper limit is preferably 300 ° C., and particularly preferably 280 ° C. Basically, if the kinematic viscosity is too low, the pour point is too high, and the flash point is too low, the low molecular weight component tends to bleed and sticky to the container lid liner surface, while the opposite is true, It is because it becomes difficult to disperse | distribute uniformly to the block copolymer of the said component (a).

(3) Component (c)
The thermoplastic elastomer constituting the thermoplastic elastomer composition for the container lid liner of the present invention must contain the olefin resin of component (c).
Examples of the olefin resin include ethylene homopolymers, other α-olefins such as propylene, 1-butene, vinyl acetate, (meth) acrylic acid, (meth) acrylic acid esters, etc., mainly composed of ethylene. Ethylene resins such as copolymers with monomers, etc .; propylene homopolymers, propylene such as copolymers with other α-olefins such as ethylene, 1-butene, etc., mainly composed of propylene Resins: 1-butene homopolymers, butene-based resins such as copolymers with other α-olefins such as ethylene and propylene, etc. containing 1-butene as the main component. Of these, propylene-based resins are preferred because of their excellent heat resistance. Specific examples include, for example, propylene homopolymers, propylene-ethylene random copolymer resins mainly composed of propylene, and propylene-ethylene block copolymers. Polymer resin etc. are mentioned.

As the polymerization mode of the olefin resin, any polymerization mode may be adopted as long as a resinous material can be obtained, but a gas phase method or a solution method is particularly preferable.
As the olefin-based resin, those having a flexural modulus measured in accordance with JIS K7203 of 200 MPa or more, preferably 300 MPa or more and 5 GPa or less are suitable. Further, the lower limit of the melt flow rate measured at a temperature of 230 ° C. and a load of 21.18 N in accordance with JIS K7210 is preferably 0.05 g / 10 min, particularly preferably 0.1 g / 10 min. The upper limit is preferably 200 g / 10 minutes, particularly preferably 100 g / 10 minutes. If the melt flow rate is too small, the molding processability as a thermoplastic elastomer composition tends to be poor and the surface appearance of the container lid liner tends to be poor, whereas if it is too large, the mechanical strength of the container lid liner tends to be poor. In addition, wear resistance tends to decrease.

(4) Composition In the present invention, the thermoplastic elastomer composition containing the components (a), (b) and (c) as essential components is the component (a) relative to the total amount of the components (a) and (b). ) And (b), the lower limit of component (a) is preferably 20%, more preferably 30%, and the upper limit is preferably 80%. More preferably, it is 75%, the upper limit of component (b) is preferably 80%, more preferably 70%, the lower limit is preferably 20%, and it is 25%. Further preferred. If the amount of component (a) is too small and the amount of component (b) is too large, the rubber elasticity and sealability of the container lid liner tend to be inferior, and the component (b) bleeds and the container lid liner surface is not sticky. On the other hand, if the component (a) is too much and the component (b) is too little, the moldability of the thermoplastic elastomer for container lid liner tends to be inferior, and flexibility as a container lid liner, Gas barrier properties and the like tend to decrease.

  On the other hand, the lower limit of the content of component (c) with respect to 100 parts by weight of the total amount of components (a) and (b) is preferably 1 part by weight, more preferably 5 parts by weight. The upper limit is preferably 300 parts by weight, more preferably 200 parts by weight, and particularly preferably 100 parts by weight. If the amount of component (c) is too small, the moldability as a thermoplastic elastomer for container lid liners tends to be inferior, while if too large, flexibility, rubber elasticity, sealing properties, etc. as container lid liners tend to be inferior.

(5) Antioxidant It is preferable to add an antioxidant to the thermoplastic elastomer composition of the present invention in addition to the above essential components. Examples of the antioxidant include monophenols, bisphenols, tri- or higher polyphenols, thiobisphenols, naphthylamines, diphenylamines, and phenylenediamines. Among these, monophenol-based, bisphenol-based, tri- or higher polyphenol-based, and thiobisphenol-based antioxidants are preferable because of their high antioxidant effects. When using antioxidant, it is 0.01-5 weight% normally with respect to the total amount of component (a)-(c), Preferably 0.05-3 weight% is used. If the amount of antioxidant is too small, it is difficult to obtain an antioxidant effect due to the use of the antioxidant. If the amount is too large, an effect commensurate with the amount of use cannot be obtained, which is economically disadvantageous, and influences such as coloring. May appear.

(6) Other components In the present invention, the thermoplastic elastomer composition containing the components (a), (b) and (c) as essential components is further heated to the extent that the effects of the present invention are not impaired. It may contain components such as a plastic resin, rubber, additive, filler, etc., but preferably contains 50% by weight or more of the essential components (a) to (c), more than 80% by weight. It is particularly preferable to include it.

Examples of the thermoplastic resin include polyphenylene ether resins ; polyamide resins such as nylon 6 and nylon 66; polyester resins such as polyethylene terephthalate and polybutylene terephthalate; polyoxymethylene homopolymers, polyoxymethylene copolymers and the like Examples thereof include oxymethylene resins ; acrylic resins such as polymethyl methacrylate; styrene resins such as polystyrene resins; polyphenylene ether resins and the like.

Examples of the rubber include ethylene / propylene copolymer rubber, ethylene / propylene / non-conjugated diene copolymer rubber, olefin rubber such as butyl rubber; polybutadiene and the like ; styrene copolymer rubber other than essential components, and the like. be able to.
Examples of the additive include a heat stabilizer, a light stabilizer, an ultraviolet absorber, a neutralizer, a lubricant, an antifogging agent, an antiblocking agent, an antistatic agent, a dispersant, a flame retardant, a conductivity imparting agent, and a coloring agent. In addition to the agent, various additives usually used for thermoplastic resins and thermoplastic elastomers can be used.

  Among these, in particular, the lubricant is often used for adjusting the opening torque of the container lid when it is installed as a container lid liner. For example, higher fatty acid amide, higher fatty acid, glycerin fatty acid ester, sorbitan fatty acid ester, propylene glycol Fatty acid esters, higher alcohol fatty acid esters, ethylene bis higher fatty acid amides, silicone oils and the like can be suitably used, and among these, higher fatty acid amides are preferred because of their high torque adjustment effect. Specific examples of higher fatty acid amides include caprylic acid amide, capric acid amide, lauric acid amide, myristic acid amide, palmitic acid amide, stearic acid amide, arachidic acid amide, behenic acid amide, oleic acid amide, and erucic acid amide. Linoleic acid amide, linolenic acid amide and the like.

Examples of the filler include glass fiber, carbon fiber, potassium titanate fiber, talc, mica, silica, titania, calcium carbonate, carbon black, and various fillers usually used for thermoplastic resins and thermoplastic elastomers. Can be mentioned.
These components may be previously contained in any of the essential components (a) to (c), or may be blended at the time of mixing or melt-kneading each component.

(7) Thermoplastic Elastomer The thermoplastic elastomer composition of the present invention is usually obtained by uniformly mixing the above components and melt-kneading them. Mixing is performed using a Henschel mixer, a ribbon blender, a V-type blender or the like. Melt kneading is preferably performed at a temperature of 100 to 300 ° C., particularly preferably 110 to 280 ° C. using a kneading apparatus such as a mixing roll, a kneader, a Banbury mixer, a Brabender plastograph, a single screw or a twin screw extruder, and the like. It is preferably performed for 10 seconds to 30 minutes, particularly preferably for 20 seconds to 20 minutes. The kneading may be performed by kneading each component at once or by using a multistage division kneading method in which each component is divided and supplied to a kneading apparatus.

(8) Dynamic thermal crosslinking The thermoplastic elastomer composition of the present invention may be dynamically heat-treated in the presence of a crosslinking agent to be partially crosslinked, and by this treatment, the thermoplastic elastomer composition is oil resistant. Heat resistance and the like can be imparted.
Examples of the cross-linking agent include organic peroxides; sulfur; cross-linking agents such as phenols, maleimides, oximes, and polyamines. Among them, organic peroxides are preferable because they easily control cross-linking. . Specific examples of suitable organic peroxides include di-t-butyl peroxide, t-butylcumyl peroxide, dicumyl peroxide, 2,5-dimethyl-2,5-di (t- Butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-di (t -Dibutyl peroxides such as -butylperoxy) -3,3,5-trimethylcyclohexane; t-butylperoxybenzoate, t-butylperoxyisopropyl carbonate, 2,5-dimethyl-2,5-di (benzoylper) Peroxyesters such as oxy) hexane, 2,5-dimethyl-2,5-di (benzoylperoxy) hexyne-3; Oxide, lauroyl peroxide, benzoyl peroxide, p- chlorobenzoyl peroxide, diacyl peroxides such as 2,4-dichlorobenzoyl peroxide; hydroperoxide, and the like, such as diisopropylbenzene hydroperoxide and the like. Among them, those having a half-life temperature of 1 minute or more at 140 ° C. are preferable. Specifically, for example, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl- 2,5-di (t-butylperoxy) hexyne-3,1,3-bis (t-butylperoxyisopropyl) benzene and the like are preferable. As for the usage-amount of a crosslinking agent, a minimum is 0.1 to 3% normally with respect to the total amount (weight ratio) of component (a)-(c), Preferably it is 0.1 to 1%.

  In addition, for the purpose of further increasing the degree of crosslinking together with the crosslinking agent during dynamic crosslinking, a crosslinking aid can also be used. Specific examples of the crosslinking aid include, for example, sulfur, p-quinonedioxime. , P-dinitrosobenzene, 1,3-diphenylguanidine, m-phenylenebismaleimide and other peroxide crosslinking aids; divinylbenzene, triallyl cyanurate, triallyl isocyanurate, diallyl phthalate and other polyfunctional vinyl compounds ; Polyfunctional (meth) acrylate compounds such as ethylene glycol di (meth) acrylate, diethylene glycol di (meth) acrylate, polyethylene glycol di (meth) acrylate, trimethylolpropane tri (meth) acrylate, and allyl (meth) acrylate are used. It is done. The amount of use (weight ratio) when using a crosslinking aid is usually 5% or less, preferably 0.1 to 3%, based on the total amount (weight ratio) of components (a) to (c).

  The dynamic heat treatment is usually carried out by kneading the melt-kneaded composition (or in the presence of the crosslinking agent (and further a crosslinking aid if necessary) in the case of dynamic thermal crosslinking). The state of the material during dynamic heat treatment varies depending on the type of material used and the dynamic heat treatment temperature, and is usually in a semi-molten state or a molten state, but is not particularly limited. In kneading, each component may be kneaded all at once, or a multistage division kneading method in which each component is divided and supplied to a kneading apparatus may be used.

(9) Container lid liner The container lid liner of the present invention is formed by, for example, molding the thermoplastic elastomer composition into a sheet shape, then cutting it into a shape that matches the shape of the container lid, and inserting and bonding it to the inner surface of the container lid. Or a method of dropping a certain amount of the composition for the container lid liner material from the extruder onto the inner surface of the container lid and inserting a pressing die into a thin liner (in-shell mold method). The The thickness of the container lid liner is an appropriate thickness according to the application, but is usually about 0.5 to 1 mm. Further, the forming into a sheet is usually performed by extrusion. 130-270 degreeC is preferable and the temperature of the composition at the time of extrusion molding has especially preferable 150-250 degreeC.

The container lid liner of the present invention is not limited to the single-layer structure of the thermoplastic elastomer composition, and may be, for example, a laminated structure having a surface coat layer on the inner surface or the outer surface.
A container lid liner comprising the composition for a container lid liner of the present invention, and a container lid formed by mounting the liner can be used by being mounted on a container using various materials such as glass, PET bottle, and aluminum. Oxygen permeation resistance is required for various food containers such as dressing, seasoning sauce, mayonnaise, salad oil and sesame oil, and various beverages such as soft drinks, alcoholic beverages, coffee beverages, tea beverages, mineral water, etc. It can be suitably used in the field.

EXAMPLES Hereinafter, the present invention will be described more specifically with reference to examples. However, the present invention is not limited to the following examples unless it exceeds the gist. In addition, each component used by the following Examples and Comparative Examples is shown below.
<Ingredients>
Component (a-1): Hydrogenated product of styrene-butadiene block copolymer having a copolymer structure of styrene block-butadiene block-styrene block (styrene content 30 wt%, weight average molecular weight 443,000, in butadiene block The ratio of 1,2-bond of the butadiene block is 37%, and the hydrogenation rate in the butadiene block is 98% or more).

Component (a-2): Hydrogenated product of styrene-butadiene / isoprene block copolymer having a copolymer structure of styrene block-butadiene / isoprene block-styrene block (styrene content 30% by weight, weight average molecular weight 342,000 The hydrogenation rate in the butadiene / isoprene block is 98% or more).
Component (A) (for comparative example): Partial hydrogenated product of styrene-butadiene block copolymer having a copolymer structure of styrene block-butadiene block-styrene block (styrene content 29% by weight, weight average molecular weight 71,300) The ratio of 1,2-bond in the butadiene block is 37%, and the hydrogenation rate in the butadiene block is 98% or more).

Component (b-1): Polybutene ("HV100" manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight 980)
Ingredient (b-2): Polybutene ("HV300" manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight 1,400)
Component (B-1) (for comparative example): Polybutene (“HV15” manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight 630)
Component (B-2) (for comparative example): Polybutene ("HV3000" manufactured by Nippon Petrochemical Co., Ltd., number average molecular weight 3,700)
Component (B-3) (for comparative example): Paraffin oil (weight average molecular weight 746, kinematic viscosity 382 cSt at 40 ° C., pour point −15 ° C., flash point 300 ° C., “PW380” manufactured by Idemitsu Kosan Co., Ltd.) .

Component (c): Propylene homopolymer resin (melt flow rate 22 g / 10 min (230 ° C., 21.2 N load)
In addition, the weight average molecular weight and number average molecular weight of each said component were measured on the following measurement conditions by the gel permeation chromatography (GPC). Model: Waters Model 150C GPC, solvent: o-dichlorobenzene, flow rate: 1 ml / min, temperature: 140 ° C., measured concentration: 2 mg / ml, injection amount: 200 μm, column: AD80M / S manufactured by Showa Denko KK

<Examples 1-3 and Comparative Examples 1-5>
Tetrakis [methylene-3- (3 ′, 5′-di-t-butyl-) is added to 100 parts by weight of the total amount of the elastomer composition in which the components are blended in the amount (parts by weight) shown in Table 1. 4′-hydroxyphenyl) propionate] methane (“Irganox 1010” manufactured by Ciba Specialty Chemicals) 0.1 part by weight, erucic acid amide 0.3 part by weight, silicon oil (“SH200-100CS” manufactured by Toray Dow Corning) ) Add 1 part by weight, melt and knead using a twin screw extruder with a compression ratio of L / D33 and a cylinder diameter of 44 mm as the former stage 110 ° C. and the latter stage 200 ° C. Extruded into a strand and cut out with a pelletizer to obtain thermoplastic elastomer composition pellets.

  From the obtained thermoplastic elastomer composition pellets, an inline screw type injection molding machine (“IS130” manufactured by Toshiba Machine Co., Ltd.) under conditions of injection pressure 50 MPa, cylinder temperature 220 ° C., mold temperature 40 ° C., 120 mm × 80 mm × thickness Three types of sheets of 2 mm, 200 mm × 200 mm × thickness 1 mm and 200 mm × 200 mm × 1 mm thickness are injection-molded, hardness, compression set, abrasion resistance, oxygen permeability, and container lid as a thermoplastic elastomer composition The impact sealability as a liner was measured, and the results are shown in Table 1.

(1) Hardness With respect to the injection-molded sheet (120 mm × 80 mm × thickness 2 mm), JIS A hardness was measured according to JIS K6253.
(2) Compression set The compression set (%) of the injection molded sheet (120 mm × 80 mm × thickness 2 mm) was measured according to JIS K6262 (70 ° C., 22 hours, 25% compression).

(3) Abrasion resistance Using a Gakushin type wear fastness tester “No. 0428” manufactured by YASUDA, the surface of the injection-molded sheet (120 mm × 80 mm × thickness 2 mm) is 5 cm at a load of 500 g. A white cotton cloth “Kanakin No. 3” of 5 cm was reciprocated 100 times, the surface was visually observed, and the degree of wear was evaluated in three stages.
○: Not scratched Δ: Almost scratched ×: Scratched (4) Oxygen permeability About the injection molded sheet (200 mm × 200 mm × thickness 1 mm), JIS
Based on K7126B, the oxygen permeability at 23 ° C. was measured.

(5) Impact sealing property The injection-molded sheet (200 mm × 200 mm × 1 mm thickness) is punched into a diameter suitable for a container lid (inner diameter: 28 mm), inserted into the inner surface of a polyprene container lid, and a container equipped with a liner A lid was made. The obtained container lid was attached to a PET (polyethylene terephthalate) bottle (capacity 500 cm ³ ) filled with distilled water heated to 95 ° C. After immersing the bottle in a constant temperature water bath adjusted to 70 ° C. to 3 cm below the container lid and heating for 30 minutes, this is flat concrete so that the top side of the bottle lid becomes the impact surface from a height of 1 m. Freely dropped on the surface. The dropping was repeated until sealing failure such as leakage of filled distilled water occurred, and the number of times until sealing failure was counted. In practice, the maximum number of drops was 30.

Claims (6)

A thermoplastic elastomer composition for container lid liners, comprising the following components (a), (b) and (c):
(A) a block copolymer represented by the general formula [(AB) _n ] and / or [(AB) _n -A] and having a weight average molecular weight of 150,000 to 1,000,000 (wherein A Represents a polymer block of vinyl aromatic hydrocarbon, B represents an elastomeric polymer block which may be hydrogenated, and n is an integer of 1 to 5.)
(B) Butene liquid polymer having a number average molecular weight of 700 to 3000 (c) Olefin resin   The content (weight) of the components (a) and (b) is 20 to 80% for the component (a) and 80 to 20 for the component (b) with respect to the total amount of the components (a) and (b). 2. The thermoplastic resin according to claim 1, wherein the content (weight) of the component (c) is 1 to 300 parts by weight per 100 parts by weight of the total amount of the components (a) and (b). Elastomer composition.   The thermoplastic elastomer composition according to claim 1 or 2, wherein the polymer block A is a styrene polymer block, and the polymer block B is a conjugated diene polymer block.   The content (weight) of the polymer block A is 10 to 50%, and the polymer block B is a butadiene polymer block, an isoprene polymer block or a butadiene / isoprene copolymer block. A thermoplastic elastomer composition.   The thermoplastic elastomer composition according to any one of claims 1 to 4, wherein the component (b) is polybutene and the component (c) is a propylene-based resin. A container lid liner using the thermoplastic elastomer composition according to any one of claims 1 to 5.