JP6369152B2 - Thermoplastic elastomer composition, molded article and cap liner - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition that is excellent in hardness, compression set, friction coefficient, appearance, and oxygen gas barrier properties and is suitable as a cap liner material. Moreover, this invention relates to the molded object and cap liner which consist of this thermoplastic elastomer composition.

  Conventionally, thermoplastic elastomer compositions have been used as cap liner materials for beverage bottle caps, food bottle caps, and the like. The cap liner material is required to make it difficult for oxygen in the air to pass through, that is, to have excellent oxygen gas barrier properties, in order to prevent oxidative deterioration of contents such as foods and beverages and to extend the expiration date. In addition, the cap liner material is also easy to open, and is required to have low frictional resistance as a material characteristic.

  As such a thermoplastic elastomer composition, for example, a composition containing a hydrogenated styrenic elastomer, liquid paraffin, polypropylene, polyethylene and a lubricant is used. Liquid paraffin is used as a softening agent for improving moldability, polypropylene is used for moldability, heat resistance and hardness adjustment, and lubricant is used for improving slidability. .

  More specifically, Patent Document 1 discloses a cross-linked thermoplastic elastomer composition using a styrene-isobutylene-styrene block copolymer (SIBS) in order to improve gas barrier properties as a cap liner material. . Patent Document 2 discloses a thermoplastic elastomer composition in which a styrene-isobutylene-styrene block copolymer (SIBS) is blended with a fatty acid amide and / or a fatty acid glyceride as a lubricant to reduce frictional resistance. Yes. Furthermore, in Patent Document 3, styrene-ethylene-butene-styrene copolymer (SEBS) and a block copolymer of butadiene are hydrogenated as those that suppress bleed out of low molecular weight components such as plasticizers. Disclosed is a thermoplastic elastomer composition in which polyethylene wax is blended with a hydrogenated conjugated diene compound block copolymer such as a block copolymer (CEBC) having a crystalline ethylene block and an amorphous ethylene-butene block. Has been.

JP 2008-013728 A JP 2008-001782 A JP 2003-231793 A

In use as a cap liner material, the thermoplastic elastomer composition is excellent in hardness, compression set, friction coefficient, appearance, and oxygen gas barrier properties, and also in hygiene because it comes in contact with food and drink. Is required.
However, according to detailed studies by the present inventors, the conventional thermoplastic elastomer compositions as described in Patent Documents 1 to 3 have the following problems, respectively. It was found that the required characteristics of the system could not be satisfied.
That is, the crosslinked thermoplastic elastomer composition of Patent Document 1 is desired to be a non-crosslinked system from the viewpoint of food hygiene.
As in Patent Document 2, just adding a fatty acid amide and / or a fatty acid glyceride as a lubricant to SIBS does not satisfy other required characteristics even if the frictional resistance can be reduced. In particular, glycerides are feared to bleed out due to heat treatment. That is, the cap liner material may be retort-sterilized at about 120 ° C., and there is a concern about the influence on the taste of the contents due to the bleed-out glycerides mixed in the contents.
Furthermore, in Patent Document 3, polyethylene wax is added to SEPS and CEBC. However, from the viewpoint of gas barrier properties, it is preferable to use SIBS, and the friction coefficient of SIBS having a higher frictional resistance than SEPS and CEBC is lowered. As a lubricant, polyethylene wax alone is not sufficient.

  The present invention solves the above-mentioned problems of the prior art, is excellent in hardness, compression set, friction coefficient, appearance, oxygen gas barrier property, and is suitable as a cap liner material from the viewpoint of food hygiene, and a molded article It is another object of the present invention to provide a cap liner.

As a result of intensive studies to solve the above problems, the present inventor has added a specific weight average molecular weight (Mw) styrene-isobutylene-styrene block copolymer to a specific weight average molecular weight (Mw) polyethylene wax and The present inventors have found that a thermoplastic elastomer composition blended with a silicone oil having a specific kinematic viscosity at a predetermined ratio can solve the above problems, and has completed the present invention.
That is, the gist of the present invention is as follows.

[1] The following component (A), component (B) and component (C) are included, and component (B) is 1 to 300 parts by weight and component (C) is 0.1 with respect to 100 parts by weight of component (A). Thermoplastic elastomer composition containing -40 parts by weight.
Component (A): Styrene-isobutylene-styrene block copolymer having a weight average molecular weight (Mw) of 80,000 to 300,000 Component (B): Weight average molecular weight (Mw) of 4,000 to 100,000 and a molecular weight Polyethylene wax component (C) having a distribution (Mw / Mn) of 3.0 or more : Silicone oil having a kinematic viscosity at 25 ° C. of 50 to 2,000 cSt

[2] The thermoplastic elastomer composition according to [1], further comprising the following component (D) and having a content of 20 to 400 parts by weight per 100 parts by weight of the component (A).
Component (D): Polypropylene resin and / or polyethylene resin

[3] The thermoplastic resin according to [1] or [2], further comprising the following component (E) and having a content of 200 to 2,000 parts by weight per 100 parts by weight of the component (A): Elastomer composition.
Component (E): Hydrogenated product of styrene-isoprene-styrene block copolymer

[4] The thermoplastic elastomer composition according to [3], wherein the component (E) has a weight average molecular weight (Mw) of 200,000 to 400,000.

[5] The heat according to any one of [1] to [4], further comprising the following component (F) and having a content of 50 to 400 parts by weight with respect to 100 parts by weight of the component (A): Plastic elastomer composition.
Component (F): Polybutene rubber softener

[6] The composition according to any one of [1] to [5], further comprising the following component (G) and having a content of 0.1 to 30 parts by weight with respect to 100 parts by weight of the component (A). A thermoplastic elastomer composition.
Ingredient (G): Fatty acid amide

[7] The thermoplastic elastomer composition according to [6], wherein the component (G) is erucic acid amide.

[8] A molded article obtained by molding the thermoplastic elastomer composition according to any one of [1] to [7].

[9] A cap liner comprising the thermoplastic elastomer composition according to any one of [1] to [7].

  According to the present invention, there is provided a thermoplastic elastomer composition excellent in hardness, compression set, friction coefficient, appearance, oxygen gas barrier property, and suitable as a cap liner material from the viewpoint of food hygiene, and the thermoplastic elastomer of the present invention. The composition provides a molded article such as a cap liner having a high commercial value.

Hereinafter, embodiments of the present invention will be described in detail.
In the present invention, the weight average molecular weight (Mw) and the number average molecular weight (Mn) are values obtained by measurement by gel permeation chromatography (GPC). The molecular weight of component (A) and component (E) is a polystyrene equivalent value, and the molecular weight of component (B) is a polyethylene equivalent value. These detailed measuring methods will be described in the examples below.

[Thermoplastic elastomer composition]
The thermoplastic elastomer composition of the present invention contains the following component (A), component (B) and component (C) in a predetermined ratio, and more preferably, the following component (D), component (E), component (F) ) And component (G).
Component (A): Styrene-isobutylene-styrene block copolymer having a weight average molecular weight (Mw) of 80,000 to 300,000 Component (B): polyethylene having a weight average molecular weight (Mw) of 4,000 to 100,000 Wax component (C): Silicone oil component (D) having a kinematic viscosity at 25 ° C. of 50 to 2,000 cSt: Polypropylene resin and / or polyethylene resin component (E): Water of styrene-isoprene-styrene block copolymer Additive component (F): polybutene rubber softener component (G): fatty acid amide

<Component (A)>
The component (A) styrene-isobutylene-styrene block copolymer (SIBS) contained in the thermoplastic elastomer composition of the present invention is mainly composed of two polymer blocks (A1) mainly composed of styrene and isobutylene. It is a triblock copolymer of (A1)-(A2)-(A1) formed from a polymer block (A2), is highly flexible, has excellent restorability, and has excellent gas barrier properties. Have.

The component (A) SIBS contains (A1)-(A2)-(A1) triblock copolymer in a proportion of 20 to 40% by weight, particularly 25 to 35% by weight of the polystyrene block of (A1). Those are preferred in terms of compression set.
Moreover, when the weight average molecular weight (Mw) of SIBS of a component (A) is less than 80,000, the compression set value of the thermoplastic elastomer composition obtained will become low, and the packing property as a cap liner will fall. On the other hand, when the weight average molecular weight (Mw) is larger than 300,000, the fluidity of the resulting thermoplastic elastomer composition is lowered and the moldability is deteriorated. Specifically, defects such as chipping occur when molded into a cap liner. Accordingly, the weight average molecular weight (Mw) of SIBS of component (A) is 80,000 to 300,000, preferably 90,000 or more, more preferably 100,000 or more, while preferably It is 300,000 or less, More preferably, it is 200,000 or less, More preferably, it is 150,000 or less.

  In addition, from the viewpoint of moldability, the SIBS of the component (A) preferably has a melt flow rate (MFR) measured at 230 ° C. and a load of 21.2 N in accordance with JIS K7210 of 0.01 g / 10 min or more. It is more preferably 0.05 g / 10 min or more, and this MFR is preferably 5.0 g / 10 min or less, and 3.0 g / 10 min or less from the viewpoint of the mechanical strength of the obtained cap liner. It is more preferable.

  In addition, the SIBS duro hardness A (JIS K6253) of the component (A) is 10 from the viewpoint of improving the followability to the mating member (bottle, container, etc. to which the cap is attached) when used as a cap liner. It is preferable that it is -99, especially 40-95.

  In addition, as SIBS, two or more types having different physical properties such as a triblock composition and a weight average molecular weight (Mw) may be used in combination.

  SIBS of component (A) can be obtained as a commercial product. As SIBS of a component (A), Kaneka's Shibusuta (trademark) series etc. are mentioned, for example, the applicable goods can be selected suitably from these, and can be used.

<Component (B)>
The polyethylene wax of component (B) contained in the thermoplastic elastomer composition of the present invention is not particularly limited as long as it has a weight average molecular weight (Mw) of 4,000 to 100,000. In the present invention, the polyethylene wax of component (B) functions as a lubricant.

  When the weight average molecular weight (Mw) of the polyethylene wax is less than 4,000, the polyethylene wax bleeds on the surface of the obtained molded product. For example, when used as a cap liner for beverages, the polyethylene wax is used for beverages. Is not preferable because of the possibility of contamination. When the weight average molecular weight (Mw) of the polyethylene wax is larger than 100,000, it becomes difficult to bleed on the surface of the molded article, and the effect as a lubricant is lowered. Accordingly, the weight average molecular weight (Mw) of the polyethylene wax is 4,000 to 100,000. Further, it is preferably 4,500 or more, more preferably 5,000 or more, and preferably 50,000 or less, more preferably 30,000 or less.

  The molecular weight distribution (Mw / Mn) of the polyethylene wax is preferably 4.0 or less, more preferably 3.8 or less, from the viewpoint of preventing bleed out of the low molecular weight polyethylene wax component. From the viewpoint of easily exerting the effect as a lubricant according to the shape, pressure applied to the molded product, temperature and humidity, etc., it is preferably 2.0 or more, more preferably 2.5 or more.

  In addition, as the component (B) polyethylene wax, two or more types having different weight average molecular weights (Mw) may be used in combination.

  In the thermoplastic elastomer composition of the present invention, the component (B) polyethylene wax is contained in an amount of 1 to 300 parts by weight with respect to 100 parts by weight of the component (A) SIBS. If the content of the polyethylene wax of the component (B) is less than the above lower limit, the effect of reducing the frictional resistance due to the blending of the polyethylene wax as a lubricant cannot be sufficiently obtained, and if it exceeds the above upper limit, the polyethylene wax bleeds. Out of the appearance of the molded product is impaired. From the viewpoint of making these points better, the content of the component (B) is preferably 3 parts by weight or more, more preferably 5 parts by weight or more with respect to 100 parts by weight of the SIBS of the component (A). On the other hand, it is preferably 270 parts by weight or less, more preferably 240 parts by weight or less, still more preferably 210 parts by weight or less, and particularly preferably 180 parts by weight or less.

  The polyethylene wax of component (B) can be obtained as a commercial product. Examples of the polyethylene wax as the component (B) include Polyethylene Homopolymers AC (registered trademark) 8 manufactured by Honeywell, and High Wax (registered trademark) 400P manufactured by Mitsui Chemicals.

<Ingredient (C)>
Component (C) is a silicone oil having a kinematic viscosity of 50 to 2,000 cSt at 25 ° C., and when used in combination with the polyethylene wax of Component (B), the friction resistance of the thermoplastic elastomer composition of the present invention is remarkably increased. It has the effect of reducing. About a component (C), kinematic viscosity in 25 degreeC can be measured by JISZ8803.

  When the kinematic viscosity at 25 ° C. of the silicone oil of component (C) is less than 50 cSt, the silicone oil bleeds on the surface of the resulting molded product, and when used as a beverage cap liner, the silicone oil is mixed into the beverage. There are concerns. Further, when the kinematic viscosity at 25 ° C. of the silicone oil of component (C) is larger than 2,000 cSt, when used as a cap liner, the opening torque is increased and it is difficult to open the plug. In order to make these effects better, the kinematic viscosity at 25 ° C. of component (C) is preferably 60 cSt or more, more preferably 70 cSt or more, while preferably 1,600 cSt or less. More preferably, it is 1,200 cSt or less, More preferably, it is 800 cSt or less.

  As the silicone oil of component (C), a linear silicone represented by the following formula (1) can be preferably used.

  In the above formula (1), each R independently represents an organic functional group that does not contain a functional group involved in the hydrosilylation addition reaction such as an alkenyl group and / or SiH group, or a hydroxyl group, and each R is the same. May be different. n represents an integer of 10 to 2000. R is preferably a methyl group, an ethyl group, or a phenyl group. Polydimethylsiloxane in which R is a methyl group is more preferable. Each independently represents an organic functional group that does not contain a functional group involved in the hydrosilylation addition reaction such as an alkenyl group and / or SiH group, or a hydroxyl group, and each R may be the same or different. n represents an integer of 10 to 2000. R preferably represents each independently a monovalent hydrocarbon group or a hydroxyl group, more preferably an alkyl group or an allyl group, still more preferably a methyl group, an ethyl group, or a phenyl group. That is, the preferred silicone oil in the present invention is a polydiorganosiloxane blocked at both ends with a triorganosilyl group, and polydialkylsiloxane, polydiallylsiloxane, polyalkylallylsiloxane, or a copolymer thereof is more preferred. More preferred is dimethylsiloxane or polymethylphenylsiloxane. When the silicone oil in the present invention has an allyl group, the ratio of the allyl group in the entire R is preferably 50% or less, and more preferably 40% or less.

  As polydimethylsiloxane, SH200 (manufactured by Toray Dow Corning), KF-96, KF-96H, KF-965, KF-968 (manufactured by Shin-Etsu Silicone), TSF451 (manufactured by Momentive Performance Materials Japan) ), AK, AKF, AKC (manufactured by Asahi Kasei Wacker Silicone Co., Ltd.) and the like are commercially available. Polymethylphenylsiloxanes include SH510, SH550, SH710 (manufactured by Dow Corning Toray), KF-50, KF-53, KF-54 (manufactured by Shin-Etsu Silicone), TSF431, TSF433, TSF4300 (momentive performance)・ Materials), AR (Asahi Kasei Wacker Silicone), etc. are available as commercial products.

  In the thermoplastic elastomer composition of the present invention, the silicone oil of component (C) is contained in an amount of 0.1 to 40 parts by weight with respect to 100 parts by weight of SIBS of component (A). If the silicone oil content is less than the above lower limit, the effect of reducing the frictional resistance due to the blending of the silicone oil cannot be sufficiently obtained. If the silicone oil content is more than the above upper limit, the appearance of the molded product is caused by bleeding out of the silicone oil. Damaged. From the viewpoint of improving these effects, the component (C) is preferably contained in an amount of 0.5 to 35 parts by weight with respect to 100 parts by weight of the component (A).

  In addition, in this invention, in order to acquire the effect of this invention effectively by using together the polyethylene wax of a component (B), and the silicone oil of a component (C), a component (B), a component (C), Are preferably used together in a weight ratio of [weight of component (B)]: [weight of component (C)] in the range of 1: 0.01 to 1:10, and 1: 0.01 to 1: More preferably, it is used in the range of 5, more preferably in the range of 1: 0.01 to 1: 1. Moreover, it is preferable to mix | blend a component (B) and a component (C) 1-300 weight part in total with respect to 100 weight part of SIBS of a component (A), especially 2-250 weight part.

<Component (D)>
The thermoplastic elastomer composition of the present invention preferably further contains a polypropylene resin and / or a polyethylene resin as the component (D). By containing component (D), fluidity at the time of molding, heat resistance, cap material, shape, hardness adjustment according to the beverage, cap (PP cap, PE cap, metal coated with olefin adhesive) The effect of imparting fusibility to the cap) is exhibited. The polypropylene resin of component (D) is not particularly limited as long as it contains more than 50% by weight of propylene units as a structural unit, and the polyethylene resin of component (D) is 50 weight units of ethylene units as a structural unit. If it contains more than%, it will not be restrict | limited.

  The thermoplastic elastomer composition of the present invention preferably contains 20 to 400 parts by weight of component (D) with respect to 100 parts by weight of SIBS of component (A). When the blending amount of the component (D) with respect to the component (A) is not more than the above upper limit, the hardness as the composition does not become too high, and when used as a cap liner, it is preferable because it is easily deformed and the packing property is improved. . On the other hand, when it is at least the above lower limit, the hardness as the composition does not become excessively low, and the cap opening torque as a cap liner is suppressed from being increased, which is preferable because it is easy to open the cap. From the viewpoint of improving these effects, the amount of component (D) is preferably 30 parts by weight or more, more preferably 40 parts by weight or more, relative to 100 parts by weight of component (A). On the other hand, it is preferably 370 parts by weight or less, more preferably 340 parts by weight or less.

  As the polypropylene resin of component (D), a propylene homopolymer, a copolymer of propylene and ethylene and / or an α-olefin having 4 to 12 carbon atoms is preferably used. As the polypropylene resin, an MFR measured at 230 ° C. and a load of 21.2 N in accordance with JIS K7210 is preferably from 1.0 to 60 g / 10 minutes from the viewpoint of moldability.

Moreover, as a polyethylene resin of a component (D), MFR measured by 190 degreeC and load 21.2N according to JISK6922 obtained by well-known methods, such as a low pressure polymerization method, is 1.0-60 g / 10min, A density of 0.91 to 0.97 g / cm ³ is preferable from the viewpoint of moldability and heat resistance.

  As the component (D), either a polypropylene resin or a polyethylene resin may be used, or both may be used in combination. Further, two or more types of polypropylene resins having different physical properties and two or more types of polyethylene resins may be used in combination.

  The polypropylene resin and / or polyethylene resin of component (D) can be obtained as a commercial product. Examples of the component (D) polypropylene resin include Novatec (registered trademark) PP series, Wintec (registered trademark) series manufactured by Nippon Polypro Co., Ltd., Prime Polypro (registered trademark) series manufactured by Prime Polymer Co., Ltd., and the like. Appropriate products can be selected and used from among them. In addition, examples of the polyethylene resin of component (D) include Novatec (registered trademark) series manufactured by Nippon Polyethylene Co., Ltd., and Creolex (registered trademark) series manufactured by Asahi Kasei Chemicals Corporation. Can be used.

<Ingredient (E)>
The thermoplastic elastomer composition of the present invention preferably further contains a hydrogenated product of styrene-isoprene-styrene block copolymer as component (E). By containing a component (E), moderate fluidity | liquidity can be provided to a thermoplastic elastomer composition, and a moldability can be improved.

  The thermoplastic elastomer composition of the present invention preferably contains 200 to 2,000 parts by weight of component (E) with respect to 100 parts by weight of SIBS of component (A). When the blending amount of the component (E) with respect to the component (A) is not more than the above upper limit, the fluidity of the resulting thermoplastic elastomer composition does not become too high, and it becomes easy to mold. Specifically, it is preferable because “chip” is less likely to occur as a cap liner molded product. On the other hand, when it is at least the above lower limit, the obtained molded product is not excessively softened, and the opening torque is suppressed (it is easy to open). Further, the fluidity does not decrease too much, and it becomes easy to mold. Specifically, it is preferable because “burrs” hardly occur as a cap liner molded product. From the viewpoint of making these effects better, the amount of component (E) is more preferably 250 parts by weight or more with respect to 100 parts by weight of component (A), while 1,500 parts by weight or less. Is more preferably 1,000 parts by weight or less, and particularly preferably 500 parts by weight or less.

  The styrene-isoprene-styrene block copolymer is formed from two polymer blocks (E1) mainly composed of styrene and a polymer block (E2) mainly composed of isoprene (E1)-(E2)- The hydrogenated styrene-isoprene-styrene block copolymer is a triblock copolymer of (E1), in which a double bond based on isoprene is hydrogenated in a polymer block (E2) mainly composed of isoprene. It is a thing. In particular, in the triblock copolymer of (E1)-(E2)-(E1), the one containing 5 to 70% by weight of the polystyrene block of (E1) is preferable in terms of compression set, and 10 to 60 What is contained in the ratio of weight% is more preferable.

  The hydrogenated styrene-isoprene-styrene block copolymer of component (E) preferably has a weight average molecular weight (Mw) in the range of 200,000 to 400,000. When the weight average molecular weight (Mw) of the hydrogenated styrene-isoprene-styrene block copolymer is 400,000 or less, when the polybutene rubber softener of component (F) is blended, this component (F) Is preferable because the polybutene rubber softening agent is less likely to bleed. On the other hand, when the weight average molecular weight (Mw) of the hydrogenated product of styrene-isoprene-styrene block copolymer is 200,000 or more, the fluidity of the resulting thermoplastic elastomer composition does not decrease too much and it becomes easy to mold. . Specifically, it is preferable because “chip” is less likely to occur as a cap liner molded product. The weight average molecular weight (Mw) of the hydrogenated styrene-isoprene-styrene block copolymer of component (E) is more preferably 220,000 or more, still more preferably 240,000 or more, Preferably it is 360,000 or less, More preferably, it is 320,000 or less.

  In addition, as a component (E), you may use together 2 or more types of different things, such as a triblock composition and a weight average molecular weight (Mw).

  A hydrogenated product of the component (E) styrene-isoprene-styrene block copolymer can be obtained as a commercial product. For example, Kuraray Co., Ltd. Hibler (registered trademark) series and the like can be mentioned, from which appropriate products can be appropriately selected and used.

<Component (F)>
The thermoplastic elastomer composition of the present invention preferably further contains a softening agent for polybutene rubber as the component (F). By containing the component (F), the thermoplastic elastomer can be used in combination with the component (E). The fluidity of the composition can be imparted and the composition can be softened. Because of this effect, the softening agent for polybutene rubbers has a high gas barrier property compared to the paraffinic oil usually used in thermoplastic elastomer compositions, so that the gas barrier property of the thermoplastic elastomer composition can be maintained. ,preferable. As the polybutene rubber softening agent, one or more of polybutene, hydrogenated polybutene and the like can be used.

The polybutene rubber softener preferably has a kinematic viscosity at 100 ° C. of 100 to 1000 mm ² / s, particularly preferably 200 to 800 mm ² / s in terms of moldability.

  The thermoplastic elastomer composition of the present invention preferably contains 50 to 400 parts by weight of component (F) with respect to 100 parts by weight of component (A). When the blending amount of the polybutene rubber softener of component (F) with respect to component (A) is less than or equal to the above upper limit, the fluidity of the thermoplastic elastomer composition does not decrease excessively and molding becomes easy. Specifically, it is preferable because “chip” is less likely to occur as a cap liner molded product. On the other hand, when it is at least the above lower limit, the fluidity does not become too high and molding becomes easy. Specifically, it is preferable because “burrs” hardly occur as a cap liner molded product. The amount of component (F) is preferably 70 parts by weight or more, more preferably 100 parts by weight or more, and preferably 380 parts by weight or less, relative to 100 parts by weight of component (A). Preferably it is 350 weight part or less.

<Component (G)>
The thermoplastic elastomer composition of the present invention preferably further contains a fatty acid amide as the component (G). By containing the component (G), the friction coefficient of the thermoplastic elastomer composition is further reduced, and the cap liner When used as a molded product, the opening torque can be reduced.

  Fatty acid amides are saturated fatty acid amides and unsaturated fatty acid amides, and saturated fatty acid amides are mainly used as antiblocking agents. Unsaturated fatty acid amides are mainly used as slip agents, and in the present invention, it is preferable to use unsaturated fatty acid amides. Unsaturated aliphatic amides mainly include monoamides and bisamides, but monoamides are faster in bleeding, and therefore have a higher effect of improving the opening torque.

  Specific examples of fatty acid amides include alkyl bis fatty acid amides such as methylene bis oleic acid amide, ethylene bis oleic acid amide, methylene bis stearic acid amide, ethylene bis stearic acid amide, oleic acid amide, stearic acid amide, erucic acid amide, etc. Fatty acid monoamides, and other substituted amides such as N-stearyl erucic acid amide and N-oleyl stearic acid amide, and one or more of these can be used, but erucic acid which is an unsaturated fatty acid monoamide Amides (melting point: 81 ° C.) and oleic acid amides (melting point: 75 ° C.) are preferred. In particular, erucic acid amide has a higher melting point and is suitable for blending into a thermoplastic elastomer composition for a cap liner that requires high-temperature sterilization. Is preferred.

  The thermoplastic elastomer composition of the present invention preferably contains 0.1 to 30 parts by weight of the component (G) with respect to 100 parts by weight of the component (A). It is preferable that the blending amount of the component (G) with respect to the component (A) is not less than the above lower limit because the friction coefficient reducing effect tends to be improved. On the other hand, when the amount is not more than the above upper limit, the component (G) is difficult to bleed out on the surface of the molded product. Specifically, when used as a cap liner molded product, the component (G) is preferable because it is difficult to be mixed into a beverage. Moreover, the fluidity | liquidity as a composition does not become high too much and it becomes easy to shape | mold. Specifically, it is preferable because “burrs” hardly occur as a cap liner molded product. From the viewpoint of making these effects more favorable, the amount of component (G) is more preferably 0.2 to 25 parts by weight with respect to 100 parts by weight of component (A). More preferably, it is part by weight.

<Other ingredients>
The thermoplastic elastomer composition of the present invention may contain other components other than the above components (A) to (G) as necessary within a range not impairing the object of the present invention.
Other components that the thermoplastic elastomer composition of the present invention may contain include various anti-blocking agents, sealability improvers, heat stabilizers, antioxidants, light stabilizers, ultraviolet absorbers, lubricants, Examples include crystal nucleating agents, colorants, and resins other than components (A) to (E).

  Here, examples of the antioxidant include 2,6-di-tert-p-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 4 , 4-dihydroxydiphenyl, tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, and the like, phenolic antioxidants, phosphite antioxidants, thioether antioxidants, and the like. Of these, phenolic antioxidants and phosphite antioxidants are particularly preferred. When using antioxidant, the compounding quantity is 0.01-3.0 weight part with respect to 100 weight part of component (A), Most preferably, it is 0.05-2.0 weight part.

  As a resin other than the components (A) to (E) that can be contained in the thermoplastic elastomer composition of the present invention, a styrenic thermoplastic elastomer (excluding those corresponding to the component (A) or the component (E)), Polyester resin, polyamide resin, styrene resin, acrylic resin, polycarbonate resin, polyvinyl chloride resin, various elastomers other than the above (excluding those corresponding to component (A) or component (E)), and the like. Other resins mentioned above may contain only one type or two or more types. However, when the thermoplastic elastomer composition of the present invention contains a resin other than components (A) to (E), the content is usually based on 100 parts by weight of the total of components (A) to (C). It is 50 parts by weight or less, and preferably 30 parts by weight or less.

<Method for producing thermoplastic elastomer composition>
The thermoplastic elastomer composition of the present invention comprises components (A) to (C), preferably further components (D) to (G), and other components to be blended as necessary. It can be manufactured by mechanically mixing with a mixer, V blender, tumbler blender or the like and then mechanically kneading and kneading by a known method. For the mechanical melt-kneading, a general melt-kneader such as a Banbury mixer, various kneaders, a single-screw or twin-screw extruder can be used.

[Molded articles and applications]
The molded article of the present invention can be obtained by molding the thermoplastic elastomer composition of the present invention. Examples of the molding method that can be used include a normal injection molding method, or various molding methods such as a gas injection molding method, an injection compression molding method, and a short shot foam molding method, if necessary. It is preferable to obtain a molded body.

  The thermoplastic elastomer composition of the present invention can be used for cap liners, caps, tubes, packing members, films, containers, etc., but the thermoplastic elastomer composition of the present invention has hardness, compression set, coefficient of friction, Since it is excellent in appearance, oxygen gas barrier properties, etc., it is particularly suitable for molding cap liners.

  When a cap liner is molded with the thermoplastic elastomer composition of the present invention, the thermoplastic elastomer composition of the present invention is hermetically molded in the cap shell using a known liner molding method. As a liner molding method, for example, the thermoplastic elastomer composition of the present invention is molded into a sheet having a thickness of 0.5 to 1.0 mm, then punched out into a diameter suitable for the shape of the cap, and inserted into the cap for adhesion. Or an in-shell mold method in which a certain amount of extruded molten resin is dropped inside the cap and embossed under cooling to form a liner. The in-shell mold method is an excellent molding method from the viewpoint of mass productivity. When the cap liner obtained by the above molding is laminated on the inner surface of the cap, the cap liner is formed on a screw-like protrusion formed on the outer periphery of the bottle mouth when the cap is put on the mouth of the bottle and tightened. The screw part formed inside the cap meshes, and the mouth of the bottle comes into contact with the flat surface of the liner on the inner surface of the cap (the horizontal part and the vertical part with respect to the bottle mouth).

  Examples of the cap to which the cap liner made of the thermoplastic elastomer composition of the present invention is applied include various tea beverages such as green tea and black tea, coffee beverages, fruit beverages, vegetable beverages, carbonated beverages, soft drinks, mineral water, and PET bottles. Name caps for containers, beer bottles, whiskey bottles, wine bottles, sake bottles such as sake bottles, wide-mouth bottles for foods such as jams and enokitake, small bottles for drinks, etc. Can do. Among these, caps used for PET bottle containers and metal bottle containers are preferable.

  EXAMPLES Hereinafter, although the content of this invention is demonstrated more concretely using an Example, this invention is not limited by a following example, unless the summary is exceeded. The values of various production conditions and evaluation results in the following examples have meanings as preferred values of the upper limit or lower limit in the embodiments of the present invention, and the preferred ranges are the upper limit or lower limit values described above, and It may be a range defined by a combination of values of the examples or values between the examples.

[material]
The materials used in the following examples and comparative examples are shown below.

<Component (A): Styrene-isobutylene-styrene block copolymer (SIBS)>
A-1 (for Examples): Trade name Shibustar (registered trademark) 103T manufactured by Kaneka Corporation
Mw: 120,000
MFR: 0.1 g / 10 min
(Measurement conditions: 230 ° C., load 21.2 N)
Duro hardness A (JIS K6253): 46
Polystyrene block ratio: 30% by weight
a-1 (for comparative example): Kaneka Corporation trade name Shibustar (registered trademark) 073T
Mw: 71,000
MFR: 6g / 10min
(Measurement conditions: 230 ° C., load 21.2 N
Duro hardness A (JIS K6253): 45

[Measurement conditions for gel permeation chromatography (GPC) of component (A)]
Equipment: HLC-8220 manufactured by Tosoh Corporation
Column: TSKgel Super HM-M manufactured by Tosoh Corporation
(6.0 mm ID X 15 cm X2 + guard column)
Detector: Differential refractive index detector (RI / built-in)
Solvent: CHCl ₃ special grade Temperature: 40 ° C
Flow rate: 0.3 mL / min Injection volume: 20 μL
Concentration: 0.1% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene conversion

<Component (B): Polyethylene wax>
B-1 (for Example): Honeywell's product name Polyethylene H
omopolymers AC (registered trademark) 8
Mw: 7,100
Mw / Mn: 3.0
B-2 (for Examples): Product name High Wax (registered trademark) 400P manufactured by Mitsui Chemicals, Inc.
Mw: 7,100
Mw / Mn: 3.5
b-1 (for comparative example): Product name Neowax L manufactured by Yasuhara Chemical Co., Ltd.
Mw: 1,500
Mw / Mn: 2.8

[Measurement conditions for gel permeation chromatography (GPC) of component (B)]
Equipment: GPCV 2000 (2) manufactured by Waters
Column: TSKgel GMH6-HT manufactured by Tosoh Corporation
(7.8 mm ID X 30 cmL X 4)
Detector: Differential refractive index detector (RI / built-in)
Solvent: ODCB special grade Temperature: 135 ° C
Flow rate: 1.0 mL / min Injection volume: 530.5 μL
Concentration: 0.1% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polyethylene conversion

<Component (C): Silicone oil>
C-1: Product name SH200-100cs manufactured by Toray Dow Corning
Kinematic viscosity (25 ° C.): 100 cSt

<Component (D): Polypropylene resin / polyethylene resin>
D-1: Nippon Polypro Co., Ltd. Product name Novatec PP (registered trademark) MA1B
(polypropylene)
MFR: 21 g / 10 min (Measurement conditions: 230 ° C., load 21.2 N (JIS K7210))
D-2: Product name Novatec (registered trademark) HJ490 manufactured by Japan Polyethylene Corporation
(polyethylene)
MFR: 20 g / 10 min (Measurement conditions: 190 ° C., load 21.2 N (JIS K6922))
Density: 0.958 g / cm ³

<Component (E): Hydrogenated product of styrene-isoprene-styrene block copolymer>
E-1: Kuraray Co., Ltd., trade name: HIBLER (registered trademark) KL-7135
Mw: 280,000
Polystyrene block ratio: 33% by weight

[Measuring conditions for gel permeation chromatography (GPC) of component (E)]
Equipment: HLC-8220 manufactured by Tosoh Corporation
Column: TSKgel Super HM-M manufactured by Tosoh Corporation
(6.0 mm ID X 15 cm X2 + guard column)
Detector: Differential refractive index detector (RI / built-in)
Solvent: CHCl ₃ special grade Temperature: 40 ° C
Flow rate: 0.3 mL / min Injection volume: 20 μL
Concentration: 0.1% by weight
Calibration sample: Monodisperse polystyrene Calibration method: Polystyrene conversion

<Component (F): Softening agent for polybutene rubber>
F-1: JX Nippon Mining & Energy Co., Ltd. Product name Nisseki Polybutene (registered trademark)
HV-300F (polybutene)
Kinematic viscosity: 550 to 625 mm ² / s (100 ° C.)

<Component (G): Fatty acid amide>
G-1: Lion Akzo product name Armoslip E (erucic acid amide)

[Evaluation method]
The evaluation methods of the thermoplastic elastomer compositions produced in the following examples and comparative examples are as follows.

(1) Hardness Based on ISO7619-1, hardness (type A durometer or type D durometer) was measured. In order to use as a cap liner material, it is preferable that the duro hardness is A99 or less and the duro hardness is D60 or less.

(2) Compression set Measured based on ISO815. For use as a cap liner material, the compression set is preferably 90% or less in order to prevent beverage leakage.

(3) Dynamic friction coefficient Using the obtained injection molded sheet (thickness 2 mm) as a test piece, the dynamic friction coefficient was measured under the following conditions with reference to ASTM D1894-90. In order to use as a cap liner material, in order to facilitate opening of the cap, it is preferable that the value of the dynamic friction coefficient is small, and evaluation was performed according to the following criteria.
Test equipment: Shinto Kagaku friction force measuring machine (slip tester)
Load weight: 63mm square, height 6.4mm, weight 200g
Movement speed: 150mm / min (evaluation criteria)
○: Dynamic friction coefficient is less than 1.0 ×: Dynamic friction coefficient is 1.0 or more

(4) Appearance of molded product After the obtained injection-molded sheet was allowed to stand in an oven at 100 ° C. for 24 hours, the appearance of the sheet surface was visually observed and evaluated according to the following criteria.
(Evaluation criteria)
○: No appearance defects such as bleed out ×: There are appearance defects such as bleed out

(5) Oxygen gas permeability Based on JIS K7126-2, the oxygen gas permeability was measured on the following conditions using the press sheet of thickness 1mm. For use as a cap liner material, the oxygen gas permeability is preferably 200 cm ³ / (m ² · 24 h · atm) or less in order to prevent oxidative deterioration of the beverage.
Equipment: OX-TRAN 2/21
Temperature and humidity: 20 ° C, dry
Transmission area: 50 cm ²

[Examples 1-3 and Comparative Examples 1-5]
The raw materials shown in Table 1 were charged at a rate of 20 kg / hr into the same-direction twin-screw extruder (“TEX30α” manufactured by Kobe Steel, L / D = 45, number of cylinder blocks: 13), and ranged from 180 to 240 ° C. The mixture was heated and melt kneaded to produce pellets of the thermoplastic elastomer composition.
The pellets of the obtained thermoplastic elastomer composition were injection molded with an in-line screw type injection molding machine (“IS100” manufactured by Toshiba Machine Co., Ltd.) under conditions of an injection pressure of 50 MPa, a cylinder temperature of 220 ° C., and a mold temperature of 40 ° C. . (1)-(4) was evaluated using the obtained injection-molded sheet (thickness 2 mm). Further, the obtained thermoplastic elastomer composition pellets were press-molded at 200 ° C. with a press molding machine to obtain a press sheet having a thickness of 1 mm, and (5) was evaluated.
The evaluation results are shown in Table-1.

[Evaluation results]
It can be seen that the thermoplastic elastomer compositions of Examples 1 to 3 have favorable evaluation results for hardness, compression set, friction coefficient, appearance, and oxygen gas permeability, and are suitable as cap liner materials.

  On the other hand, since the comparative example 1 used the styrene-isobutylene-styrene block copolymer (SIBS) (a-1) with a low weight average molecular weight, its compression set was bad. In Comparative Example 2, since the component (B) polyethylene wax was not used, the coefficient of dynamic friction was large. In Comparative Example 3, since the polyethylene wax of component (B) was used in a large amount, the polyethylene wax bleeded out, and the appearance of the molded product was poor. Moreover, since the comparative example 4 used polyethylene wax (b-1) with a low weight average molecular weight, polyethylene wax bleeded out and the external appearance of the molded article was bad. Moreover, although the comparative example 5 used the polyethylene wax as a lubricant, since the component (C) was not used together, the dynamic friction coefficient was large.

Claims (9)

Including the following component (A), component (B), and component (C), 1 to 300 parts by weight of component (B) and 0.1 to 40 parts by weight of component (C) with respect to 100 parts by weight of component (A) A thermoplastic elastomer composition comprising parts.
Component (A): Styrene-isobutylene-styrene block copolymer having a weight average molecular weight (Mw) of 80,000 to 300,000 Component (B): Weight average molecular weight (Mw) of 4,000 to 100,000 and a molecular weight Polyethylene wax component (C) having a distribution (Mw / Mn) of 3.0 or more : Silicone oil having a kinematic viscosity at 25 ° C. of 50 to 2,000 cSt Furthermore, the thermoplastic elastomer composition of Claim 1 which contains the following component (D) and whose content is 20-400 weight part with respect to 100 weight part of component (A).
Component (D): Polypropylene resin and / or polyethylene resin Furthermore, the thermoplastic elastomer composition of Claim 1 or 2 which contains the following component (E) and whose content is 200-2,000 weight part with respect to 100 weight part of component (A).
Component (E): Hydrogenated product of styrene-isoprene-styrene block copolymer   The thermoplastic elastomer composition according to claim 3, wherein the component (E) has a weight average molecular weight (Mw) of 200,000 to 400,000. Furthermore, the thermoplastic elastomer composition of any one of Claims 1 thru | or 4 which contains the following component (F) and whose content is 50-400 weight part with respect to 100 weight part of component (A). object.
Component (F): Polybutene rubber softener Furthermore, the thermoplasticity of any one of Claim 1 thru | or 5 which contains the following component (G) and whose content is 0.1-30 weight part with respect to 100 weight part of component (A). Elastomer composition.
Ingredient (G): Fatty acid amide   The thermoplastic elastomer composition according to claim 6, wherein component (G) is erucic acid amide.   The molded object formed by shape | molding the thermoplastic elastomer composition of any one of Claims 1 thru | or 7.   A cap liner comprising the thermoplastic elastomer composition according to any one of claims 1 to 7.