JP2007091770A - Composition for cap liner - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a composition for a cap liner having excellent hermetic sealability (flexibility and recovering properties), gas barrier properties, retort resistance and sanitary properties, easily unsealable during practical use and usable for a sealing material of a cap for beverages and to provide the cap liner using the composition. <P>SOLUTION: The problems are solved by providing the composition as follows. An isobutylene polymer having alkenyl groups at the terminals is dynamically cross-linked with a hydrosilyl group-containing compound in the presence of crystalline polypropylene and an ethylenic copolymer and a lubricant are further added to the resultant dynamiclly cross-linked isobutylene polymer. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention is a composition for a cap liner used for a sealing material for a beverage cap, which has excellent sealing properties, gas barrier properties, heat resistance, hygiene, and is easy to open during actual use, and The present invention relates to a cap liner using the same. More specifically, the excellent flexibility, restorability, and gas barrier properties of the cross-linked isobutylene polymer not only provide a good sealing performance after retorting, but also allow oxygen to permeate soft drinks and other contents. Oxidation and gas escape from contents such as carbonated beverages with internal pressure are unlikely to occur, abnormal increase in opening torque is prevented, easy opening during actual use, and elution from liner material is prevented. Further, the present invention relates to a cap liner composition used for a sealing material for a beverage cap having excellent hygiene, and a cap liner using the same.

  Conventionally, liner materials such as cork, soft PVC, olefin resins such as low density polyethylene, and styrene elastomers have been used as liner materials for container lids such as glass bottles, metal bottles, and PET containers. Among these, although cork is excellent in impact resilience and the like, it is a natural material and has problems such as quality, supply stability, and dust generation. Further, although PVC-based materials are flexible and have excellent sealing properties, there are problems such as elution of plasticizers and generation of dioxins during low temperature incineration. Under these circumstances, in recent years, it has been changed to liner materials such as olefin resins and styrene elastomers having excellent hygiene and processability.

  However, when an olefin resin such as low-density polyethylene is used as the liner material, plastic deformation and permanent deformation of the contents that require high-temperature filling, heat sterilization treatment, and contents such as carbonated beverages that are subject to internal pressure Problems such as leakage occur from the point, and there is also a problem in leakiness against impacts during transportation. For this reason, liner materials mainly composed of a styrene-based elastomer having excellent hermetic sealing properties are mainly used for the above-mentioned applications.

  As such a liner material mainly composed of a styrene-based elastomer, a composition comprising a hydrogenated styrene-butadiene block copolymer, a polyolefin, and a softening agent such as liquid paraffin is generally used. Yes (Patent Documents 1 to 4). By using such a composition, it is flexible and excellent in hermetic sealability, can withstand hot filling (hot fill) of the contents and heat sterilization after filling and sealing (retort sterilization), and can be thermally deformed or heated. A liner material that effectively eliminates leakage due to shrinkage has been obtained. However, on the other hand, the hydrogenated styrene-butadiene block copolymer has a high gas permeability compared to polyolefin, and has a low ability to block oxygen from the outside, so that the content is easily oxidized, There is a problem that the period during which the flavor and aroma can be maintained is short. In addition, when the content is a carbonated beverage, there is a problem that the carbon dioxide gas escapes quickly and the period during which the internal pressure can be maintained is short. Furthermore, in order to express sufficient hermetic sealing properties, it is necessary to add a large amount of a softening agent such as liquid paraffin to impart flexibility. However, in a content containing fat such as a milk beverage, the softening agent Is easy to elute, and there is a problem in terms of hygiene.

  On the other hand, as a liner material excellent in gas barrier properties, a liner material mainly composed of butyl rubber has been proposed (Patent Document 5). However, in order to crosslink the butyl rubber described in Patent Document 5, it is necessary to use a crosslinking agent such as a phenol resin or zinc oxide, which not only has problems such as coloring and odor of the liner material, The elution to the contents is high, and there are problems in terms of safety and hygiene.

Japanese Patent Laid-Open No. 2-57569 JP 7-76360 A JP-A-11-106565 JP 2000-38495 A JP 2002-160759 A

  An object of the present invention is a composition for a cap liner used for a sealing material for a beverage cap, which has excellent sealing properties, gas barrier properties, is excellent in retort resistance and hygiene, and can be easily opened in practical use, and It is to provide a cap liner using the same. More specifically, an object of the present invention is to provide a cap liner composition that can provide sufficient openability even after heat (sterilization) treatment, and a cap liner using the same.

  As a result of intensive studies to solve the above problems, the inventors of the present invention dynamically cross-linked an isobutylene polymer having an alkenyl group at a terminal with a hydrosilyl group-containing compound in the presence of crystalline polypropylene, Furthermore, it discovered that the said subject could be solved by using the composition which added the ethylene-type copolymer and the lubricant as a liner material, and came to this invention.

  That is, in the present invention, (A) 100 parts by weight of an isobutylene polymer having an alkenyl group at the terminal is melt kneaded with (C) a hydrosilyl group-containing compound in the presence of 10 to 60 parts by weight of crystalline polypropylene. It is related with the composition for cap liners which contains the composition bridge | crosslinked inside, (D) 5-50 weight part of ethylene-type copolymers, and (E) 0.1-20 weight part of lubricant.

  As a preferred embodiment, it further comprises (F) 1 to 300 parts by weight of a block copolymer comprising a polymer block (a) mainly composed of an aromatic vinyl compound and a polymer block (b) mainly composed of isobutylene. And a cap liner composition.

  As a preferred embodiment, the present invention further relates to a cap liner composition further comprising (G) 1 to 100 parts by weight of a softening agent.

  As a preferred embodiment, the present invention relates to (D) a composition for a cap liner, wherein the ethylene copolymer is at least one selected from ethylene-ethyl acrylate and ethylene-methyl acrylate.

  As a preferred embodiment, the present invention relates to a composition for a cap liner, wherein the polypropylene as the component (B) is a random polypropylene.

  As a preferred embodiment, the present invention relates to a cap liner composition, wherein the lubricant of component (E) is at least one selected from the group consisting of fatty acid amides and silicone oils.

  In a preferred embodiment, the content of the block (a) in the block copolymer of the component (F) is 10 to 40% by weight, for a cap liner according to any one of claims 2 to 6 Relates to the composition.

  A preferred embodiment relates to a composition for a cap liner, wherein the softening agent for the component (F) is polybutene.

  Moreover, this invention relates to the cap liner which consists of the said composition.

  A composition obtained by crosslinking an isobutylene polymer having an alkenyl group at a terminal with a hydrosilyl group-containing compound during melt-kneading in the presence of a polyolefin as in the present invention, and using a lubricant, sealing property, gas barrier It can be set as the composition which is excellent in the property, and is excellent in retort resistance and hygiene. In addition, by using crystalline polypropylene and a soft ethylene copolymer as the polyolefin, it becomes possible to achieve both heat resistance and openability, which was difficult to achieve with the addition of a single polyolefin.

  The cap liner made of the composition of the present invention has not only good shape followability at the time of sealing due to the excellent flexibility and gas barrier property of the isobutylene polymer, but also due to the permeation of oxygen to the contents such as soft drinks. Oxidation and outgassing from contents such as carbonated beverages with internal pressure hardly occur. Furthermore, by adding an ethylene copolymer, moldability is improved, flexibility is imparted, and torque at the time of opening is reduced. In addition, the addition of a lubricant prevents an abnormal increase in the opening torque, and can be easily opened during actual use. Furthermore, by crosslinking the isobutylene polymer having an alkenyl group at the terminal with a hydrosilyl group-containing compound, heat resistance is imparted and component elution from the liner material is prevented. As a result, a cap liner having excellent hygiene can be obtained. Therefore, the cap liner made of the composition of the present invention can be suitably used as a cap liner for soft drinks, carbonated drinks, milk drinks and the like.

  The cap liner composition of the present invention comprises (A) 100 parts by weight of an isobutylene polymer having an alkenyl group at the terminal, (B) in the presence of 10 to 60 parts by weight of crystalline polypropylene, It is obtained by mixing a composition obtained by crosslinking during melting and kneading with a compound, (D) 5 to 50 parts by weight of an ethylene copolymer, and (E) 0.1 to 20 parts by weight of a lubricant.

  The isobutylene polymer having an alkenyl group at the terminal, which is the component (A) of the present invention, is a unit derived from isobutylene accounting for 50% by weight or more, preferably 70% by weight or more, more preferably 90% by weight or more. Means a polymer having an alkenyl group at the terminal. 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.

  Although there is no restriction | limiting in particular in the molecular weight of (A) component, It is preferable that it is 5,000 to 500,000 by weight average molecular weight by GPC measurement, and 10,000 to 200,000 is especially preferable. When the weight average molecular weight is less than 5,000, mechanical properties and the like tend not to be sufficiently exhibited. When the weight average molecular weight exceeds 500,000, the melt-kneading property is lowered and the reactivity at the time of crosslinking is lowered. Tend to.

  The alkenyl group in the component (A) of the present invention is not particularly limited as long as it is a group containing a carbon-carbon double bond that is active for a crosslinking reaction with a hydrosilyl group-containing compound. Specific examples include aliphatic unsaturated hydrocarbon groups such as vinyl group, allyl group, methyl vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, cyclopropenyl group, cyclobutenyl group, cyclopentenyl group, cyclohexenyl group. And cyclic unsaturated hydrocarbon groups such as

  As a method for introducing an alkenyl group into the terminal of the component (A) of the present invention, there is a heavy group having a functional group such as a hydroxyl group as disclosed in JP-A-3-152164 and JP-A-7-304909. A method of introducing an unsaturated group into the polymer by reacting a compound having an unsaturated group with the polymer is exemplified. In order to introduce an unsaturated group into a polymer having a halogen atom, a method of performing a Friedel-Crafts reaction with alkenylphenyl ether, a method of performing a substitution reaction with allyltrimethylsilane in the presence of a Lewis acid, various phenols, etc. And a method of performing the above-mentioned alkenyl group introduction reaction after introducing a hydroxyl group by performing a 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 alkenyl group in the component (A) of the present invention may be appropriately adjusted depending on the required properties. However, the component (A) is preferably at least 0.2 alkenyl groups per molecule from the viewpoint of the properties after crosslinking. It is preferably a polymer having a group at the terminal, 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 crystalline polypropylene which is the component (B) of the present invention is crystalline, homopolypropylene, random type polypropylene, block type polypropylene and a mixture thereof, or an oxidized, halogenated or sulfonated one of these polymers. Etc. can be used singly or in combination of two or more. Specific examples include propylene-ethylene random copolymers, propylene-ethylene block copolymers, and polypropylene resins such as chlorinated polypropylene. Among these, random type polypropylene can be preferably used from the viewpoint of balance between cost and physical properties.

  Although there is no restriction | limiting in particular as a melt flow rate (MFR) of the polypropylene to be used, it is preferable that it is 0.1-100 (g / 10min) from the point of shaping | molding fluidity | liquidity, and 1-100 (g / 10min) It is more preferable that

  In the present invention, the component (B) not only functions as a cross-linking reaction field for the component (A), but also functions to impart molding fluidity, heat resistance, mechanical strength, and openability to the final liner composition. Have. Component (B) is added in an amount of 10 to 60 parts by weight and preferably 20 to 50 parts by weight per 100 parts by weight of component (A). When the component (B) is less than 10 parts by weight, sufficient molding fluidity and heat resistance tend not to be obtained, and when it exceeds 60 parts by weight, flexibility tends to be impaired and sufficient sealability tends not to be exhibited. is there.

In the present invention, the hydrosilyl group-containing compound (C) 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, Various hydrosilyl group containing polysiloxane can be used preferably. Of these, a hydrosilyl group-containing polysiloxane having 3 or more hydrosilyl groups and 3 or more and 500 or less siloxane units is preferred, and a polysiloxane having 3 or more hydrosilyl groups and 10 or more and 200 or less siloxane units. Is more preferable, and polysiloxane having 3 or more hydrosilyl groups and 20 to 100 siloxane units is particularly preferable. When 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. When the number of siloxane units exceeds 500, the viscosity of 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);

（式中、Ｒ⁴およびＲ⁵は炭素数１〜６のアルキル基、または、フェニル基、Ｒ⁶は炭素数１〜１０のアルキル基またはアラルキル基を示す。ｅは３≦ｅ、ｄ，ｅ，ｆはｄ＋ｅ＋ｆ≦５００を満たす整数を表す。）等の化合物を用いることができる。

(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 component (A) and the hydrosilyl group-containing compound can be mixed at an arbitrary ratio, but the amount of the hydrosilyl group relative to the alkenyl group (hydrosilyl group / alkenyl group) is 0.5 to It is preferably in the range of 10, more preferably 1 to 5. When the molar ratio is smaller than 0.5, crosslinking tends to be insufficient, and when it is larger than 10, a large amount of active hydrosilyl groups remain even after crosslinking, so that volatile components tend to be generated.

  The crosslinking reaction between the component (A) and the component (C) 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 the catalyst other than platinum _{compounds, RhCl (PPh 3) 3,} RhCl 3, RuCl 3, IrCl 3, FeCl 3, AlCl 3, PdCl 2 · H 2 O, NiCl 2, TiCl 4 , 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 catalyst amount, It is good to use in the range of 10 ^{< -1} > ^-10 <^-8> mol with respect to 1 mol of alkenyl groups of (A) component, Preferably it is the range of 10 ^{< -3} > ^-10 <^-6> mol. It is good to use. 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, in the presence of the component (B), the component (A) is cross-linked by the component (C) while being melt-kneaded (dynamic crosslinking).

  The temperature for melt kneading is preferably 130 to 240 ° C. If the temperature is lower than 130 ° C., the component (B) 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, component (A) and component (B) are essential, but other components such as component (D), component (E), component (F), and component (G) are suitably used. Crosslinking may be performed after adding. However, since some of the components (E) inhibit the crosslinking reaction, the component (E) is preferably added after crosslinking. In addition, when the crosslinking catalyst is added after being mixed with the component (G), the mixture is uniformly diffused and mixed, and the uniformity of the crosslinking reaction tends to be improved. Therefore, such a method is preferably used. The component (G) preferably promotes the mixing of the components (A) and (B) and promotes the uniform progress of the crosslinking reaction, so that the total amount or a part of the blended amount is preferably added before crosslinking.

  There is no restriction | limiting in particular as a method for melt-kneading, A well-known method is applicable. For example, the component (A) and the component (B), and other components blended for obtaining predetermined physical properties are mixed with a heat kneader such as a single screw extruder, twin screw extruder, roll, Banbury mixer, It can be produced by melt-kneading using a lavender, kneader, high shear mixer or the like.

  The order of addition is as follows. After component (B) is melted, component (A) is added. If necessary, other components are added and mixed uniformly, and then a crosslinking agent and a catalyst are added. And a method of allowing the crosslinking reaction to proceed is preferred.

  The ethylene copolymer that is component (D) of the present invention has a JIS-A hardness of 90 or less, a random copolymer of ethylene and another unsaturated monomer, a block copolymer, a graft copolymer. The polymers and the oxidized, halogenated or sulfonated ones of these polymers can be used alone or in combination of two or more. Specifically, ethylene-butene copolymer, ethylene-hexene copolymer, ethylene-octene copolymer, ethylene-vinyl acetate copolymer, ethylene-vinyl alcohol copolymer, ethylene-ethyl acrylate copolymer, ethylene -Methyl acrylate copolymer, ethylene-acrylic acid copolymer, ethylene-methyl acrylate-maleic anhydride copolymer and the like are exemplified. Among these, ethylene-ethyl acrylate copolymer and ethylene-methyl acrylate copolymer are preferable from the viewpoint of flexibility and lubricant bleeding.

  Component (D) is added in an amount of 5 to 50 parts by weight, preferably 10 to 40 parts by weight per 100 parts by weight of component (A). When the component (D) is less than 5 parts by weight, there is a tendency that sufficient flexibility cannot be obtained, and when it is more than 50 parts by weight, the heat resistance tends to be impaired.

  The lubricant which is the component (E) of the present invention is added mainly for the purpose of imparting openability (openability) and moldability. As the lubricant, fatty acid amide lubricants, fatty acid metal salt lubricants, fatty acid ester lubricants, fatty acid lubricants, aliphatic alcohol lubricants, partial esters of fatty acids and polyhydric alcohols, paraffin lubricants, silicone lubricants and the like are preferably used. Two or more of these may be selected and used. Fatty acid amide lubricants include erucic acid amide, oleic acid amide, stearic acid amide, behenic acid amide, ethylene bis stearic acid amide, ethylene bis oleic acid amide, ethylene biserucic acid amide, ethylene bis lauric acid amide, m-xylyl Examples include lenbis stearic acid amide and p-phenylene bis stearic acid amide. Examples of the fatty acid metal salt lubricant include calcium stearate, magnesium stearate, aluminum stearate, zinc stearate, and barium stearate. Fatty acid ester lubricants include methyl laurate, methyl myristate, methyl palmitate, methyl stearate, methyl oleate, methyl erucate, methyl behenate, butyl laurate, butyl stearate, isopropyl myristate, isopropyl palmitate Octyl palmitate, octyl palmitate, octyl stearate, octyl stearate, special beef tallow fatty acid octyl ester, lauryl laurate, stearyl stearate, behenyl behenate, cetyl myristate, hardened beef tallow, castor hardened oil and the like. Examples of fatty acid-based lubricants include stearic acid, palmitic acid, oleic acid, linoleic acid, linolenic acid and the like. Examples of the aliphatic alcohol include stearyl alcohol, cetyl alcohol, myristyl alcohol, and lauryl alcohol. Examples of the partial ester of fatty acid and polyhydric alcohol include stearic acid monoglyceride, stearic acid diglyceride, and olein monoglyceride. Examples of the paraffinic lubricant include paraffin wax, liquid paraffin, polyethylene wax, oxidized polyethylene wax, and polypropylene wax. In addition, montanic acid and its derivatives, such as montanic acid ester, montanic acid metal salt, montanic acid partially saponified ester, and silicone oil are also used. These may be used alone or in combination. Among these, fatty acid amides are preferable, and erucic acid amide is most preferable from the viewpoints of the effect of improving the opening and molding processability and the influence on the flavor and aroma of the contents. In addition, by using a paraffin wax such as paraffin wax, polyethylene wax, or polypropylene wax in combination, the molding fluidity can be greatly improved, and by using silicone oil in combination, the opening performance can be further improved. . For the purpose of improving the mixing and dispersibility of the silicone oil, a master batch with polyolefin may be used. For example, silicone concentrate BY-27 series (manufactured by Toray Dow Corning Silicone Co., Ltd.), silicone master pellet X-22 series (manufactured by Shin-Etsu Chemical Co., Ltd.), hexasilicone ML series (manufactured by Hexa Chemical Co., Ltd.), etc. Goods.

  (E) A component mixes 0.1-20 weight part with respect to 100 weight part of (A) component. Preferably 0.1 to 10 parts by weight, more preferably 0.1 to 5 parts by weight is mixed. If it exceeds 20 parts by weight, the dispersibility becomes insufficient, the component (E) tends to bleed out, and the mechanical strength of the resulting composition tends to decrease, such being undesirable. On the other hand, when the amount is less than 0.1 parts by weight, the effect of improving the pluggability and molding processability tends to be insufficient.

  In the present invention, for the purpose of improving the molding fluidity, gas barrier properties, mechanical properties, etc., the polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene as the main component (F) as necessary. 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.

  The component (F) of the present invention is not particularly limited as long as it is composed of the block (a) and the block (b). For example, the component (F) has a linear, branched, or star structure. Any of a block copolymer, a diblock copolymer, a triblock copolymer, a multiblock copolymer, and the like 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 (F) is not particularly limited, but is preferably 30,000 to 500,000 in terms of weight average molecular weight by GPC measurement from the viewpoint 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 (F) component, For example, it can obtain by polymerizing a monomer component in presence of the compound represented by following General formula (1).
(CR ¹ R ² X) nR ³ (1)
[Wherein X is a halogen atom, a substituent selected from an alkoxy group having 1 to 6 carbon atoms or an acyloxy group, R ¹ and R ² are each a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms, R ¹ , R ² may be the same or different, R ³ is a polyvalent aromatic hydrocarbon group or a polyvalent aliphatic hydrocarbon group, and n represents a natural number of 1-6. ]

  The compound represented by the general formula (1) serves as an initiator, and is considered to generate a carbon cation in the presence of a Lewis acid or the like and serve as a starting point for cationic polymerization. Examples of the compound of the general formula (1) 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 ]

Of these, bis (1-chloro-1-methylethyl) benzene [C ₆ H ₄ (C (CH ₃ ) ₂ Cl) ₂ ], tris (1-chloro-1-methylethyl) benzene [( ClC (CH ₃ ) ₂ ) ₃ C ₆ H ₃ ]. [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 (F) is produced, a Lewis acid catalyst can be present together. 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 (1), Preferably it is the range of 1-50 mol equivalent.

  In the production of the component (F), 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 (F) 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 (F) and the solubility of the polymer to be formed.

  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, the respective components are 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.

  Component (F) is preferably mixed in an amount of 1 to 300 parts by weight, more preferably 1 to 200 parts by weight, based on 100 parts by weight of component (A). If it exceeds 300 parts by weight, the restoring property (compression set) tends to deteriorate.

  In the present invention, as the component (G), a softener can be used as necessary for the purpose of imparting flexibility and molding fluidity. Although it does not specifically limit as a softening agent, Generally, a liquid or liquid material is used suitably at room temperature. Examples of such softeners include various rubber or resin softeners such as mineral oils, vegetable oils, and synthetics. Mineral oils include naphthenic and paraffinic process oils, and vegetable oils include castor oil, cottonseed oil, linseed oil, rapeseed oil, soybean oil, palm oil, palm oil, peanut oil, wax, pine Examples of synthetic systems include oil and olive oil, and polybutene and low molecular weight polybutadiene. Among these, polybutene is preferably used from the viewpoint of compatibility with the component (A) and gas barrier properties. These softeners can be used in an appropriate combination of two or more in order to obtain the desired hardness and melt viscosity.

  The amount of component (G) is preferably 1 to 100 parts by weight, more preferably 1 to 50 parts by weight, and more preferably 1 to 30 parts by weight per 100 parts by weight of component (A). Is more preferable. When the amount exceeds 100 parts by weight, the softener tends to be eluted from the liner material to the contents, which is not preferable.

  The cap liner composition of the present invention is excellent in gas barrier properties, but can further contain an oxygen absorbent for absorbing oxygen in the container and dissolved oxygen in the contents. As such an oxygen absorbent, known ones can be used, and there is no particular limitation. For example, ascorbic acid (vitamin C), ascorbate, isoascorbic acid, isoascorbate, gallic acid, gallate, propyl gallate, isopropyl citrate, glucose, fructose and other sugars, BHT, BHA, EDTA Alkali metal salt, tocopherol (vitamin E), hydroquinone, catechol, resorcin, dibutylhydroxytoluene, dibutylhydroxyanisole, pyrogallol, longalit, sorbose, glucose, lignin and other organic oxygen absorbers, iron powder, active iron, first oxide Iron-based oxygen absorbers such as iron and iron salt, inorganic oxygen absorbers such as sulfite, thiosulfate, dithionite, and bisulfite, polybutadiene, polyisoprene, or copolymers thereof, poly (Meta-xylenediamine-azi Acid) (for example, MXD6 manufactured by Mitsubishi Gas Chemical Co., Ltd. is commercially available), poly (ethylene-methyl acrylate-benzyl acrylate), poly (ethylene-methyl acrylate-tetrahydrofurfuryl acrylate), poly (ethylene -Methyl acrylate-cyclohexenyl methyl acrylate), polyhydric phenol-containing phenol-aldehyde resins, redox resins having an oxidizable (reducing) active group, or polymer-based oxygen absorption such as polymer metal complexes One or a mixture of two or more selected from oxygen adsorbents such as an adsorbent, zeolite, and activated carbon is appropriately used according to the conditions of use. When the oxygen absorbent is in a powder form, the particle size is not particularly limited, but in general, a smaller one is preferable in terms of increasing the surface area.

The oxygen absorbent may contain other substances such as a catalyst, a water retention agent and a hydrate in order to control the oxygen absorption capacity. For example, an electrolyte can be used in combination with the iron-based oxygen absorbent. The electrolyte is for accelerating the oxygen absorption rate of the iron-based oxygen absorbent, and examples thereof include alkali metal or alkaline earth metal halides, carbonates, sulfates and hydroxides. Among these, a halide is particularly preferable, and CaCl ₂ , NaCl, MgCl _{2 and the} like are more preferable. The electrolyte can be used by coating or blending with the iron-based oxygen absorbent particles.
The amount of the electrolyte added is generally about 0.1 to 10% by weight with respect to the iron-based oxygen absorbent.

  In addition, a transition metal catalyst for oxidation reaction can be used in combination with the oxidation-reduction resin used as the polymeric oxygen absorbent. Examples of the transition metal catalyst include metal salts such as acetic acid, naphthenic acid, stearic acid, acetylacetonate complex, or molybdenum of hydrochloric acid, iron, cobalt, rhodium, and nickel.

  Furthermore, a photosensitizer can be used in combination with the redox resin. As the photosensitizer that can be used, known ones such as a cleavage type and a hydrogen abstraction type can be used, but a hydrogen abstraction type is preferably used. Specific examples of the cleavage type include those having a benzoin derivative, benzyl ketal, α-hydroxyacetophenone, and α-aminoacetophenone skeleton. Examples of the hydrogen abstraction type photosensitizer include those having a benzophenone, Michler ketone, anthraquinone, or thioxanthone skeleton. These may be used alone or in combination.

  In addition, other thermoplastic resins, thermoplastic elastomers, unvulcanized rubber, and the like can be added to the cap liner 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. Further, examples of the unvulcanized 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 (F) is used, polyphenylene ether is preferably used for the purpose of improving its heat resistance. In addition, hydrogenated styrenic elastomers such as SEBS and SEPS are also preferably used for the purpose of adjusting moldability and openability.

  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 mix | blended with the composition for cap liners of this invention from a physical property improvement or an economical 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 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 cap liners of this invention as needed, and the amount of mixing is 0.01-10 with respect to 100 weight part of (A) component. It is preferable to set it as a weight part, and it is more preferable to set it as 0.01-5 weight part. 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.

  There is no restriction | limiting in particular in the manufacturing method of the composition for cap liners of this invention, A well-known method is applicable. For example, the above-mentioned components, and optionally additive components, are melted using a heat kneader, such as a single screw extruder, twin screw extruder, roll, Banbury mixer, Brabender, kneader, high shear mixer, etc. It can be manufactured by kneading.

  The kneading order of each component is not particularly limited except that the isobutylene polymer (A) is melt-kneaded and crosslinked with the hydrosilyl group-containing compound (C) in the presence of the crystalline polypropylene (B). It can be determined according to the apparatus to be used, workability, or physical properties of the obtained cap liner composition.

  As the hardness of the cap liner composition of the present invention, the hardness measured with a spring type A durometer defined in JIS K-6253 (hereinafter abbreviated as JIS-A hardness) is 40 to 75. Preferably, it is 45-65. If the JIS-A hardness is less than 40, the liner material strength is weak and the liner tends to be worn when the cap is opened and closed. If the JIS-A hardness exceeds 75, the liner is too hard and sufficiently adheres to the mouth of the container. It is difficult and the hermetic sealing performance of the container contents tends to be impaired. Also, if the hardness is high, the force required to compress the cap liner at the time of closing increases, so in order to obtain the same sealing performance, the torque required for closing increases for plastic caps, and for metal caps, beverages The pressure (head pressure) applied to the cap at the time of threading after filling increases, and as a result, the opening torque tends to increase.

  In producing the cap liner of the present invention, although not particularly limited, various commonly used molding methods and molding apparatuses can be used according to the type, application, and shape of the target cap. Examples of the molding method include injection molding, extrusion molding, press molding, blow molding, calendar molding, cast molding, and the like, and these methods may be combined.

  As a specific manufacturing method, a cap liner composition is formed into a sheet having a thickness of 0.5 to 1.0 mm, punched into a diameter suitable for the shape of the cap, and then inserted into the cap and bonded. Alternatively, an in-shell molding method or the like in which a certain amount of extruded molten resin is dropped inside the cap and is embossed under cooling to form a liner shape. The in-shell mold method is an excellent molding method from the viewpoint of mass productivity.

  The cap liner composed of the cap liner composition of the present invention may be used as a single layer or in combination with a layer having other functions. Examples of the layer having other functions include an oxygen absorption layer. The oxygen absorbing layer is exemplified by a layer in which the above-described oxygen absorbent is dispersed in a polymer such as polyolefin.

  Caps in which the cap liner composition of the present invention is used include various types of tea beverages, fruit beverages, vegetable beverages, carbonated beverages, milk beverages, coffee beverages, soft drinks, mineral water PET bottle containers, metal bottle containers, beer And caps for containers used for bottles for alcoholic beverages such as whiskey, wine and sake, wide-mouthed bottles for food such as jam and enokitake, small bottles for drinks and the like. Among these, it is particularly suitable for a cap of a container used for a PET bottle container or a metal bottle container.

  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 of the block copolymer and the physical properties of the cap liner composition shown in this example 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.

(Seal seal)
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. A case where the JIS-A hardness was 45 to 65 was evaluated as ◯, a case where the JIS-A hardness was 40 to 45 or 65 to 75 was determined as Δ, and a case where it was less than 40 or exceeded 95 was evaluated as ×. In addition, when JIS-A hardness is 45-65, sufficiently high sealing performance will be obtained for use as a cap liner.

(Openability)
A 1 mm thick press sheet was used as a test piece, which was attached to the bottom of a 38 mmφ metal can cap, and then the cap was left in an oven at 50 ° C. for 24 hours and attached to a bottle containing 150 cc city water. The tightening angle of the cap was 75 ° from the place where the cap and the test sheet touched. The bottle with the cap attached was retorted on a pressure cooker PC305S made by Hirayama Seisakusho at 125 ° C for 1 hour, and then left at room temperature for 5 days, using a torque meter 2TME450CN made by Tohnichi Seisakusho. The opening torque was measured. The case where the opening torque was less than 220 N · cm was evaluated as ◯, 220 to 240 N · cm as Δ, and 240 N · cm as x. Note that the opening torque of less than 220 N · cm means an opening level that allows easy opening by hand.

(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. The oxygen permeability coefficient is less than 1 × 10 ⁻¹⁵ mol · m / m ² · sec · Pa, ○, and 1 × 2 × 10 ⁻¹⁵ mol · m / m ² · sec · Pa is Δ, 2 × 10 ⁻¹⁵ mol · The case of exceeding m / m ² · sec · Pa was evaluated as x. When the oxygen permeability coefficient is less than 1 × 10 ⁻¹⁵ mol · m / m ² · sec · Pa, it can also be suitably used for containers of beverages that are easily affected by oxygen such as tea drinks, milk drinks, and beer.

(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. When it is 50% or more under these conditions, the restoration property is insufficient, and the sealing property is impaired after hot fill or retort sterilization. The case where it was less than 50% was marked as ◯, the case where it was 50-59% was marked as Δ, and the case where it was 60% or more was marked as x.

(Elution)
20 g of a 2 mm thick press sheet was precisely weighed, 10 times the amount of water was added and sealed, and heated at 121 ° C. for 1 hour. The mixture was allowed to cool to room temperature, 100 ml of the eluate was accurately measured, evaporated to dryness on a water bath, dried at 105 ° C. for 1 hour, and the weight of the residue was measured. Under these conditions, 2 mg or more of the eluate is x, 1-2 mg is Δ, 1 mg or less is o.

(Molding fluidity)
Based on JIS K-7210 method A, the flow rate per 10 minutes (MFR) was measured at 230 ° C. with a 2.16 kgf load. If it does not flow under these conditions, the molding fluidity is insufficient.

A cap liner composition was produced using the following raw materials.
Component (A) Isobutylene polymer having an alkenyl group at its terminal Component manufactured in the following Preparation Example Component (B) Polypropylene Polypropylene (random type): Mitsui Chemicals, Inc. Mitsui Polypro J215W (MFR: 9 g / 10 min, hereinafter RPP) Abbreviated)
Component (C) 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 (D) Ethylene copolymer Ethylene-ethyl acrylate copolymer: EVAFLEX EEA A702 (hereinafter abbreviated as EEA1) manufactured by Mitsui DuPont Co., Ltd.
Ethylene-ethyl acrylate copolymer: EVAFLEX EEA A713 (hereinafter abbreviated as EEA2) manufactured by Mitsui DuPont Co., Ltd.
Ethylene-methyl acrylate copolymer: Elvalloy AC A1820c (hereinafter abbreviated as EMA) manufactured by Mitsui DuPont Co., Ltd.
Component (E) Lubricant Erucamide: Neutron-S (hereinafter abbreviated as EA) manufactured by Nippon Seika Co., Ltd.
Silicone oil: Silicone concentrate BY27-001 manufactured by Toray Dow Corning Silicone Co., Ltd., silicone oil content of about 50% (hereinafter abbreviated as SiMB)
Component (F) Isobutylene-based block copolymer Manufactured in the following Production Example 2 Component (G) Softening agent Polybutene: Idemitsu Kosan Co., Ltd. Idemitsu Polybutene 100R (hereinafter abbreviated as 100R)
Paraffinic oil: Diana Process PW-90 (hereinafter abbreviated as PW90) manufactured by Idemitsu Kosan Co., Ltd.
Thermoplastic elastomer Hydrogenated styrene-butadiene block copolymer: Clayton G1650 manufactured by Kraton Polymer Japan Co., Ltd. (styrene content 29%, hereinafter abbreviated as SEBS)

(Production Example 1) (A) Isobutylene copolymer having an alkenyl group at the terminal (hereinafter abbreviated as APIB)
A 2 L separable flask was fitted with a three-way cock, a thermocouple, and a stirring seal, and was purged with nitrogen. 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 contained allyl group determined by ¹ H-NMR was 2.0 / mol.

(Production Example 2) (F) Isobutylene block copolymer, triblock structure having a styrene content of 30% (hereinafter abbreviated as SIBS)
After replacing the inside of the polymerization vessel of the 500 mL separable flask with nitrogen, add 97.6 mL of n-hexane (dried with molecular sieves) and 140.5 mL of butyl chloride (dried with molecular sieves) using a syringe. After the polymerization vessel was cooled in a dry ice / methanol bath at −70 ° C., the pressure-resistant glass liquefied collection tube with a three-way cock containing 47.7 mL (505.3 mmol) of isobutylene monomer was made of Teflon (registered trademark). The liquid feeding tube was connected, and the isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. 0.097 g (0.42 mmol) of p-dicumyl chloride and 0.073 g (0.84 mmol) of N, N-dimethylacetamide were added. Next, 1.66 mL (15.12 mmol) of titanium tetrachloride was further added to initiate polymerization. After stirring for 75 minutes from the start of polymerization, about 1 mL of the polymerization solution was extracted from the polymerization solution for sampling. Subsequently, 13.71 g (131.67 mmol) of styrene monomer was 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 GPC analysis of the obtained isobutylene type block copolymer was conducted, the weight average molecular weight was 135000 and the polystyrene content calculated | required by < ¹ > H-NMR was 30 weight%.

(Production Example 3) Dynamic cross-linking composition comprising (A) component, (B) component, (C) component, and (G) component ((B) component is RPP, (A) / (B) / ( G) = 100/11/40 parts by weight (hereinafter abbreviated as TPV))
We measured 26.3 g of APIB (component (A)) obtained in Production Example 1 and 2.9 g of RPP (component (B)) and set Labo Plast Mill (Toyo Seiki Seisakusho Co., Ltd.) at 170 ° C. The mixture was melt-kneaded for 2 minutes, 10.5 g of 100R (component (G)) was added, and the mixture was further kneaded for 2 minutes. Next, 0.32 g of H-oil which is a hydrosilyl group-containing compound (amount of hydrosilyl group in component (C) (4 equivalents of hydrosilyl group / alkenyl group) with respect to alkenyl group in component (A)) was added for 1 minute. After kneading, 14.8 μl of a crosslinking catalyst was added, and melt-kneading was further continued until crosslinking progressed 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.

  (Production Example 4) A dynamic crosslinking composition was prepared in the same manner as in Production Example 3 except that the component (B) was changed to the component (D).

(Examples 1-9)
Lab Plast Mill (manufactured by Toyo Seiki Seisakusho Co., Ltd.) blended so that the final composition of each component is as shown in Table 1, using the dynamic cross-linking composition produced in Production Example 3. Was melt-kneaded for 5 minutes. The charged weight was adjusted to 45 g in total. The obtained kneaded material was press-molded at 170 ° C. for 5 minutes, and various physical properties were evaluated. The evaluation results are shown in Table 1.

(Comparative Examples 1-3, 5, 6)
The same evaluation as in Examples 1 to 9 was performed except that the composition was changed as shown in Table 1. The results are shown in Table 1.

(Comparative Example 4)
Using the dynamic crosslinking composition prepared in Production Example 4, the same evaluation as in Examples 1 to 9 was performed. The results are shown in Table 1.

  It can be seen that Comparative Example 1 in which the component (D) is not blended has high hardness and high opening torque. In Comparative Example 2, the hardness was lowered by reducing the component (B) in the composition of Comparative Example 1, but it was found that the fluidity was unsatisfactory. In Comparative Example 3, the hardness was reduced by increasing the blending amount of the component (G), but it was found that the opening torque was high and the gas barrier property was slightly low. It can be seen that Comparative Example 4 in which the component (B) is not blended has poor compression set at high temperatures and high opening torque. It can be seen that Comparative Example 5 containing no component (E) has a very high opening torque. Moreover, although the comparative example 6 is a composition which has the hydrogenated styrene conjugated diene type block copolymer (SEBS) which is a prior art as a main component, it turns out that gas barrier property is inadequate.

  As described above, in Examples 1 to 9 of the present invention, it can be seen that the above-mentioned problems are not present and the composition is balanced as a liner material for the cap. In Examples 3 and 6, the hardness is not adjusted by increasing or decreasing the components (B) and (G) as in Comparative Examples 2 and 3, but by adding the component (D), the hardness is the same as in Comparative Examples 2 and 3. However, it can be seen that the opening torque is lower and better in Examples 3 and 6. This is presumably because the bleeding effect of the lubricant of the component (E) was promoted by the addition of the ethylene copolymer of the component (D), and the active effect was increased.

From the above, the composition according to the present invention is an object of the present invention, which is excellent in hermetic sealing property, gas barrier property, restoration property, hygiene, and easy to open after heat sterilization in actual use. It was shown that there is.

Claims (9)

  (A) 100 parts by weight of an isobutylene polymer having an alkenyl group at the terminal is cross-linked during melt kneading with (C) a hydrosilyl group-containing compound in the presence of 10 to 60 parts by weight of crystalline polypropylene. A composition for a cap liner comprising the composition, (D) 5 to 50 parts by weight of an ethylene copolymer, and (E) 0.1 to 20 parts by weight of a lubricant.   The block copolymer 1 to 300 further comprising (F) a polymer block (a) mainly composed of an aromatic vinyl compound and a polymer block (b) mainly composed of isobutylene. A cap liner composition comprising parts by weight.   A composition for a cap liner, further comprising (G) 1 to 100 parts by weight of a softening agent in the composition according to claim 1.   4. The cap liner composition according to claim 1, wherein (D) the ethylene copolymer is at least one of ethylene-ethyl acrylate and ethylene-methyl acrylate.   The composition for cap liner according to any one of claims 1 to 4, wherein the polypropylene as the component (B) is random polypropylene.   The composition for cap liner according to any one of claims 1 to 5, wherein the lubricant of component (E) is at least one selected from the group consisting of fatty acid amides and silicone oils.   The composition for a cap liner according to any one of claims 2 to 6, wherein the content of the block (a) in the block copolymer of the component (F) is 10 to 40% by weight.   The composition for cap liner according to any one of claims 3 to 7, wherein the softening agent for component (G) is polybutene.   A cap liner comprising the composition according to claim 1.