JP4859498B2 - Thermoplastic elastomer composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition that does not contain impurities that affect hygiene even in a high-temperature sterilization process at 120 ° C. or more, is suitable for food use and medical use, and has excellent flexibility and compression set properties.

  Polyorganosiloxane rubber, that is, silicone rubber, is superior in physiological inertness (non-toxic), weather resistance, durability, releasability, heat resistance, etc., medical equipment, building materials, electrical / electronic parts It is used in various fields such as automobile parts and OA equipment parts. Among them, silicone rubber (addition-curing type) that cures by hydrosilylation reaction can be cured by heating, so it has good productivity and there are no by-products during the curing reaction. For example, it is particularly useful. However, the cured silicone rubber does not have thermoplasticity like general crosslinked rubber.

  In contrast, thermoplastic elastomers (TPE) are polymeric materials that have both plastic and rubber properties. TPE has the mechanical properties of an elastomer, but unlike conventional thermoset rubbers, it can be reworked at high temperatures. This reworkability allows for reuse of the processed parts, resulting in a reduction in the amount of parts discarded. In this respect, it can be said that TPE is superior to chemically crosslinked rubber.

  In general, two main types of thermoplastic elastomers are known. One is what is called a block copolymer thermoplastic elastomer that contains both "hard" and "soft" segments. The “hard” segment has a melting point or glass transition temperature higher than ambient temperature. The “soft” segment has a glass transition temperature that is significantly lower than room temperature. In these systems, the hard segments agglomerate to form distinct microphases and act as physical cross-linking points for the soft phase, thereby imparting rubbery properties at room temperature. At high temperatures, the hard segments melt or soften, and this melting or softening allows the copolymer to flow and be processed like a normal thermoplastic.

  The other type can be obtained by intimately mixing an elastomer component and a thermoplastic resin. When the elastomer component is crosslinked, a thermoplastic elastomer known in the art as a thermoplastic vulcanizate (TPV) is obtained. TPV generally exhibits higher oil and solvent resistance than non-crosslinked blends and exhibits low compression set. Usually, TPV is a method known as dynamic vulcanization in which an elastomer and a matrix resin made of a thermoplastic resin are mixed and the elastomer is cured by the action of a crosslinking agent and / or a catalyst during the mixing process. It is formed by. Many such TPVs are known in the art, and as such TPV, the cross-linked elastomer component is a silicone polymer and the thermoplastic resin component is an organic non-silicone polymer (ie, a thermoplastic silicone vulcanizate or TPSIV). Some are known.

  For example, Patent Document 1 discloses a polyolefin resin composition obtained by dynamically crosslinking an addition reaction curable liquid silicone rubber composition during kneading with a polyolefin resin and a molded product thereof. In Patent Document 2, a polyolefin resin composition obtained by dynamically crosslinking a condensation-curable liquid silicone rubber composition during kneading with a polyamide thermoplastic polyurethane or a styrene block copolymer in addition to a polyolefin resin and a molded product thereof Is disclosed.

  These compositions are thermoplastic elastomers with the hygienic properties of silicone rubber and low compression set, but are extremely hard because they are a mixture with crystalline polyolefin, and the flexibility of conventional silicone rubbers. Did not have.

  In this way, the conventional thermoplastic elastomers that use silicone rubber as the elastomer component do not provide the thermoplastic elastomer with the flexibility of the original silicone rubber, and the appearance of low-hardness silicone rubber-based thermoplastic elastomers. Was desired.

JP 2003-226352 A JP 2000-109696 A

  An object of the present invention is to provide a silicone rubber-based thermoplastic elastomer excellent in hygiene, flexibility, and compression set characteristics.

  As a result of intensive research to solve the above problems, the present inventors have found that an isobutylene block copolymer comprising a polymer block mainly composed of an aromatic vinyl compound and an isobutylene polymer block, and a polyorganosiloxane. It has been found that the above-mentioned problems can be solved by using a composition containing rubber in a predetermined ratio and dynamically crosslinking the polyorganosiloxane rubber when these are melt-kneaded. .

  That is, the present invention provides an isobutylene block copolymer (A) comprising a polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene polymer block (b) and a polyorganosiloxane rubber (B). Block copolymer (A) / organosiloxane rubber (B) = 10/90 to 95/5, and when melt-kneading isobutylene block copolymer (A) and polyorganosiloxane rubber (B) The present invention relates to a thermoplastic elastomer composition obtained by dynamically crosslinking a polyorganosiloxane rubber (B).

  A preferred embodiment is a thermoplastic elastomer composition in which the polyorganosiloxane rubber (B) is crosslinked by a hydrosilylation reaction.

  In a preferred embodiment, the polyorganosiloxane rubber (B) comprises a polyorganosiloxane (C) containing an organohydrogenpolysiloxane, a polyorganosiloxane (D) having at least two alkenyl groups in one molecule, and a platinum-based rubber. The catalyst (E) comprises (silicon-bonded hydrogen atom contained in polyorganosiloxane (C)) / (alkenyl group contained in polyorganosiloxane (D)) = 0.5 / 1 to 1 / 0.5 ( There is a thermoplastic elastomer composition having a molar ratio).

  As a preferred embodiment, when the total amount of the isobutylene block copolymer (A) and the polyorganosiloxane rubber (B) is 100 parts by weight, the heat containing 0 to 300 parts by weight of the filler (F). There are plastic elastomer compositions.

  The composition of the present invention is a thermoplastic elastomer composition having the hygienic properties, rubber elasticity, and flexibility of silicone rubber, does not contain impurities that affect hygiene, is flexible, and has excellent elasticity close to rubber. It is a thermoplastic elastomer having low extractability, and can be said to be extremely suitable for food applications and medical applications that require excellent hygiene and physical properties similar to rubber.

  The thermoplastic elastomer composition of the present invention comprises an isobutylene block copolymer (A) comprising a polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene polymer block (b), and a polyorganosiloxane rubber. (B) is contained in a ratio of isobutylene block copolymer (A) / organosiloxane rubber (B) = 10/90 to 95/5, and the isobutylene block copolymer (A) and the polyorganosiloxane rubber (B ) Is obtained by dynamically crosslinking the polyorganosiloxane rubber (B) during melt kneading.

  As a preferred structure of the isobutylene block copolymer (A) of the present invention, a polymer block comprising an aromatic vinyl monomer as a main monomer component from the viewpoint of physical properties and processability of the resulting composition- Polymer block containing isobutylene as the main monomer component-Triblock copolymer formed from polymer block containing aromatic vinyl monomer as the main monomer component, isobutylene as the main monomer component Polymer block-Polymer block containing aromatic vinyl monomer as monomer main component-Triblock copolymer formed from polymer block containing isobutylene as monomer main component, aromatic vinyl monomer Polymer block containing monomer as monomer main component-Diblock copolymer formed from polymer block containing monomer component based on isobutylene, and aromatic vinyl monomer as monomer main component component At least one can be mentioned the di-block copolymer formed isobutylene from the polymer block whose monomer major component is selected from the group consisting of star-shaped polymer to be the arm - polymer block.

  Aromatic vinyl monomers 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 -Dimethylstyrene, 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. These may be used alone or in combination of two or more.

  The polymer block containing an aromatic vinyl monomer as a main monomer component may contain a monomer other than the aromatic vinyl monomer. The monomer which is not the main component of the present invention is preferably 40% by weight or less, more preferably 20% by weight or less, more preferably 5% by weight based on the aromatic vinyl monomer, as will be described later. More preferably, it is as follows. The monomer that is not the main component is not particularly limited as long as it is a monomer component capable of cationic polymerization, but aliphatic olefins, dienes, vinyl ethers, silanes, vinyl carbazole, β-pinene, acenaphthylene, and the like. The monomer of can be illustrated. These may 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, isobutylene and the like. These may be used alone or in combination of two or more.

  Examples of the diene monomer include butadiene, isoprene, hexadiene, cyclopentadiene, cyclohexadiene, dicyclopentadiene, divinylbenzene, and ethylidene norbornene. These may be used alone or in combination of two or more.

  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. These may be used alone or in combination of two or more.

  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. These may be used alone or in combination of two or more.

  Further, the aromatic vinyl monomer constituting the aromatic vinyl polymer block of the present invention is 60% by weight or more in the aromatic vinyl polymer block from the balance between physical properties and polymerization characteristics. Is preferable, more preferably 80% by weight or more, and still more preferably 95% or more. As the aromatic vinyl monomer, it is preferable to use at least one monomer selected from the group consisting of styrene, α-methylstyrene, p-methylstyrene, and indene. From the viewpoint of cost, styrene, α It is particularly preferred to use methylstyrene or a mixture thereof.

  The polymer block based on isobutylene of the present invention may or may not contain a monomer other than isobutylene, but is usually 60% by weight or more, preferably 80% by weight or more, more preferably It is composed of 95% or more isobutylene. The monomer other than isobutylene is not particularly limited as long as it is a monomer capable of cationic polymerization, and examples thereof include the above monomers.

  The ratio of the polymer block containing isobutylene as the main monomer component and the polymer block containing aromatic vinyl as the main monomer component is not particularly limited. The polymer block containing isobutylene as the main monomer component is 98 to 40% by weight, and the polymer block containing aromatic vinyl as the main monomer component is 2 to 60% by weight based on the total amount of the polymer block. More preferably, the polymer block containing isobutylene as the main monomer component is 95 to 60% by weight, and the polymer block containing aromatic vinyl as the main monomer component is 5 to 40% by weight. It is particularly preferable that the polymer block containing isobutylene as the main monomer component is 90 to 70% by weight, and the polymer block containing aromatic vinyl as the main monomer component is 10 to 30% by weight.

  The molecular weight of the isobutylene block copolymer is not particularly limited, but is preferably 5,000 to 1,500,000 in terms of weight average molecular weight from the viewpoint of moldability, processability, physical properties and the like. More preferably, it is preferably from 20,000 to 500,000, particularly preferably from 20,000 to 250,000, and particularly preferably from 40,000 to 125,000. When the weight average molecular weight of the isobutylene block copolymer is lower than the above range, the physical properties are not sufficiently expressed. On the other hand, when the weight average molecular weight exceeds the above range, it is disadvantageous in terms of the balance among moldability, workability, and physical properties. It is. Within the above range, an appropriate molecular weight can be selected according to the molding method such as injection molding and extrusion molding.

  The molecular weight distribution (ratio of weight average molecular weight (Mw) to number average molecular weight (Mn) (Mw / Mn)) is preferably 10 or less, more preferably 5 or less, from the viewpoint of moldability, workability, physical properties, etc. Preferably it is 3 or less.

Although there is no restriction | limiting in particular about the manufacturing method of an isobutylene type block copolymer (a), For example, in the presence of the compound represented by following General formula (1), the monomer and isobutylene which have isobutylene as a main component are shown. It is obtained by polymerizing a monomer component which is not a main component.
(CR ¹ R ² X) _n R 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. ]

  Examples of the halogen atom include chlorine, fluorine, bromine, iodine and the like. It does not specifically limit as said C1-C6 alkoxyl group, For example, a methoxy group, an ethoxy group, n-, or an isopropoxy group etc. are mentioned. It does not specifically limit as said C1-C6 acyloxyl group, For example, an acetyloxy group, a propionyloxy group, etc. are mentioned. It does not specifically limit as said C1-C6 hydrocarbon group, For example, a methyl group, an ethyl group, n-, or an isopropyl group etc. are mentioned.

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 ]
Among these, particularly preferred are 1,4-bis (1-chloro-1-methylethyl) benzene [1,4-Cl (CH ₃ ) ₂ CC ₆ H ₄ C (CH ₃ ) ₂ Cl], 1, 3,5-tris (1-chloro-1-methylethyl) benzene [1,3,5- (ClC (CH ₃ ) ₂ ) ₃ C ₆ H ₃ ]. [Note that 1,4-bis (1-chloro-1-methylethyl) benzene is also called bis (α-chloroisopropyl) benzene, bis (2-chloro-2-propyl) benzene or dicumyl chloride, 3,5-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 isobutylene block copolymer is produced by polymerization, a Lewis acid catalyst can be allowed to coexist. Such Lewis acid may be any one that can be used for cationic polymerization. TiCl ₄ , TiBr ₄ , BCl ₃ , BF ₃ , BF ₃ .OEt ₂ , SnCl ₄ , SbCl ₅ , SbF ₅ , WCl ₆ , TaCl ₅ , VCl ₅ , FeCl ₃ , ZnBr ₂ , AlCl ₃ , AlBr _3, etc .; metal halides such as Et ₂ AlCl, EtAlCl _2, etc. can be preferably used. Of these, TiCl ₄ , BCl ₃ , and SnCl ₄ are preferable in view of the ability as a catalyst and industrial availability. The amount of Lewis acid used is not particularly limited, but can be set in view of the polymerization characteristics or polymerization concentration of the monomer used. Usually, it is 0.1-100 mol equivalent with respect to the compound represented by General formula (1), Preferably it is the range of 1-50 mol equivalent.

  In the polymerization of the isobutylene block copolymer, an electron donor component can be further present if necessary. This electron donor component is considered to have an effect of stabilizing the growth carbon cation during cationic polymerization, and a polymer having a controlled structure with a narrow molecular weight distribution is formed by addition of the electron donor. 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 amount of the electron donor component used is not particularly limited, but can be set in view of the polymerization characteristics or polymerization concentration of the monomer used. Usually, the compound represented by the general formula (1) can be used in an amount of 0.5 to 10 mole equivalent, preferably 1 to 8 mole equivalent.

  The polymerization of the isobutylene block copolymer can be carried out in an organic solvent as necessary, and the organic solvent can be used without any particular limitation as long as it does not essentially 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 are used alone or in combination of two or more in consideration of the balance of the polymerization characteristics of the monomers constituting the block copolymer and the solubility of the resulting polymer. The amount of the solvent used is determined so that the total concentration of the monomers is 1 to 50 wt%, preferably 5 to 35 wt% in consideration of the viscosity of the polymer solution obtained and ease of heat removal. .

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

  In addition, a star-shaped polymer having a diblock copolymer formed of a polymer block containing an aromatic vinyl monomer as a monomer main component and a polymer block containing isobutylene as a monomer main component as an arm. The production method is not particularly limited. For example, in the presence of a compound having three or more cationic polymerization initiation points, a monomer having an aromatic vinyl monomer as a main component and isobutylene as a main component. A diblock copolymer by polymerizing a monomer component comprising an aromatic vinyl monomer and a monomer component comprising isobutylene as a main component, And a method of coupling (bonding) the diblock copolymer using a polyfunctional compound as a coupling agent (binder).

  As said polyfunctional compound, the compound etc. which have the reaction point (functional group) which can be coupled 3 or more per molecule can be used. When a compound having two reaction points per molecule is polymerized or reacted to form a polymer to have three or more reaction points (functional groups), the use is not hindered.

  Examples of such polyfunctional compounds include 1,3-divinylbenzene, 1,4-divinylbenzene, 1,2-diisopropenylbenzene, 1,3-diisopropenylbenzene, 1,4-diiso Propenylbenzene, 1,3-divinylnaphthalene, 1,8-divinylnaphthalene, 2,4-divinylbiphenyl, 1,2-divinyl-3,4-dimethylbenzene, 1,3-divinyl-4,5,8-tributyl Divinyl aromatic compounds such as naphthalene and 2,2′-divinyl-4-ethyl-4′-propylbiphenyl; 1,2,4-trivinylbenzene, 1,3,5-trivinylnaphthalene, 3,5, Trivinyl aromatic compounds such as 4′-trivinylbiphenyl and 1,5,6-trivinyl-3,7-diethylnaphthalene; cyclohexane diepoxy , Diepoxides such as 1,4-pentane diepoxide, 1,5-hexane diepoxide; diketones such as 2,4-hexane-dione, 2,5-hexane-dione, 2,6-heptane-dione; Examples include dialdehydes such as 4-butane dial, 1,5-pentane dial, and 1,6-hexane dial; siloxane compounds, calixarene, and the like. These may be used alone or in combination of two or more.

  Among these, divinyl aromatic compounds are preferably used from the viewpoint of reactivity, physical properties of the resulting star polymer, and the like, and 1,3-divinylbenzene, 1,4-divinylbenzene, 1,3- It is at least one selected from the group consisting of diisopropenylbenzene and 1,4-diisopropenylbenzene. The above compound is usually commercially available as a mixture with, for example, ethyl vinyl benzene, etc., and can be used as it is if the above divinyl aromatic compound is the main component, and can be purified as necessary to purify it. You may raise and use.

  The polyorganosiloxane rubber (B) of the present invention is not particularly limited as long as it is usually used, and the curing method may be any of addition curing type, organic peroxide curing type, etc. Addition-curable silicone rubber compositions, especially those containing organohydrogenpolysiloxane (C), alkenyl group-containing organopolysiloxane (D) and platinum compound (E) from the standpoint of hygiene Is preferred.

  The organohydrogenpolysiloxane of the component (C) of the present invention acts as a crosslinking agent for the alkenyl group-containing organopolysiloxane of the component (D) and has hydrogen atoms (SiH directly bonded to silicon atoms in the molecule). It is necessary to include at least two bonds. The hydrosilylation reaction is insufficient when the amount of the organohydrogensiloxane is less than the amount of SiH groups that provides 0.5 times moles of the total number of alkenyl groups in the component (D). Exceeding the amount of SiH groups provided in a molar amount causes the product to become brittle or excessive SiH bonds remain to cause aging, so that the total number of alkenyl groups in component (D) is 0.5. It is necessary to set the amount within a range of supplying hydrogen atoms directly bonded to silicon atoms to be 2.0 times moles. Preferably it is 0.75-1.5 times mole.

Such an organohydrogensiloxane may be linear, branched or cyclic as long as it has at least two silicon-bonded hydrogen atoms in the molecule, and those represented by the following general formula are preferred.
R ⁴ _a H _b SiO _{(4-ab) / 2}
Here, R ⁴ is the same group as R ¹ and represents a hydrogen atom or a monovalent hydrocarbon group having 1 to 6 carbon atoms. Of these, a methyl group is preferred. a and b are numbers satisfying 0 ≦ a <3, 0 <b ≦ 2, and 0 <a + b <4.

Specifically, a linear organopolysiloxane whose ends are sealed with dimethylhydrogensilyl groups, an organopolysiloxane having dimethylsiloxane units and methylhydrogensiloxane units in the main chain blocked with trimethylsilyl groups, and dimethyl Low viscosity fluid having hydrogen siloxane units and SiO ₂ units, 1,3,5,7-tetrahydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1-propyl-3,5,7- Examples include trihydrogen-1,3,5,7-tetramethylcyclotetrasiloxane, 1,5-dihydrogen-3,7-dihexyl-1,3,5,7-tetramethylcyclotetrasiloxane.

  The alkenyl group-containing organopolysiloxane (D) contains at least 1.5, preferably at least 2, alkenyl groups having 2 to 8 carbon atoms such as vinyl, allyl and propenyl groups, preferably vinyl groups. Is preferred. Moreover, organic groups other than an alkenyl group are C1-C8 unsubstituted or substituted monovalent hydrocarbon groups which do not have an aliphatic unsaturated group. As this organopolysiloxane, the following formula is particularly preferred.

（式中、Ｖｉはビニル基であり、Ｒ⁵は炭素数１〜１０の非置換又は置換一価炭化水素基で、アルキル基、アルケニル基、アリール基、アラルキル基などが挙げられ、特にＲ⁵としてはビニル基、フェニル基、炭素数１〜８のアルキル基、炭素数３〜１０のフルオロアルキル基及びそれらの混合物からなる群から選んだ基であることが好ましい。また、Ｒ⁶は脂肪族不飽和結合を含まない炭素数１〜１０の非置換又は置換一価炭化水素基で、好ましくはフェニル基、炭素数１〜８のアルキル基、炭素数３〜１０のフルオロアルキル基及びそれらの混合物からなる群から選んだ基であり、ｍ及びｎは（ａ）成分の粘度をコントロールする因子であり、少なくとも１．５個、好ましくは少なくとも２個の範囲のビニル基濃度を持つように選定される数である。

(Wherein, Vi is vinyl radical, R ⁵ is an unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms, an alkyl group, an alkenyl group, an aryl group, an aralkyl group, especially R ⁵ Is preferably a group selected from the group consisting of a vinyl group, a phenyl group, an alkyl group having 1 to 8 carbon atoms, a fluoroalkyl group having 3 to 10 carbon atoms, and a mixture thereof, and R ⁶ is aliphatic. An unsubstituted or substituted monovalent hydrocarbon group having 1 to 10 carbon atoms that does not contain an unsaturated bond, preferably a phenyl group, an alkyl group having 1 to 8 carbon atoms, a fluoroalkyl group having 3 to 10 carbon atoms, and mixtures thereof Wherein m and n are factors that control the viscosity of component (a) and are selected to have a vinyl group concentration in the range of at least 1.5, preferably at least 2. Ru It is.

Examples of the alkyl group that can be represented by R ⁵ and R ⁶ include a methyl group, an ethyl group, and a propyl group, and examples of the fluoroalkyl group include a 3,3,3-trifluoropropyl group. More preferably, R ⁵ is a vinyl group or a methyl group, and R ⁶ is a methyl group.

  The platinum or platinum compound as component (E) may be a known catalyst as an addition reaction catalyst. Specifically, platinum black or platinum supported on silica, carbon black or the like, chloroplatinic acid, chloroplatinic acid alcohol Examples thereof include a solution, a complex salt of chloroplatinic acid and an olefin, and vinyl siloxane, and the alkenyl group-containing organopolysiloxane (D) may be mixed in advance before crosslinking. Component (E) is preferably added in an amount of 0.0001 to 0.1 parts by weight with respect to 100 parts by weight of both components (C) and (D) in order to achieve a practical curing rate.

  The blending amount of the (B) component combining the (C) component, the (D) component, and the (E) component is 5 to 95 weights when the total amount of the (A) component and the (B) component is 100 parts by weight. Parts and preferably 20 to 80 parts by weight. If the amount is less than 5 parts by weight, the rubber elasticity is poor, and if it exceeds 95 parts by weight, there is a problem in terms of moldability.

  The filler (F) of the present invention is not particularly limited, and clay, diatomaceous earth, silica, talc, barium sulfate, calcium carbonate, magnesium carbonate, mica, graphite, aluminum hydroxide, magnesium hydroxide, natural silicic acid, synthetic silicic acid ( Inorganic fillers such as white carbon) and metal oxides (titanium oxide, magnesium oxide, zinc oxide) can be used. Of these, calcium carbonate, talc, and silica are particularly preferable from the viewpoint of cost and mechanical strength. Further, silica is preferable from the viewpoint of the reinforcing effect. Specifically, fumed silica, precipitated silica and the like are used alone or in combination of two or more. Of these, those obtained by subjecting fumed silica to surface hydrophobization treatment with chlorosilane or silazane are preferred. In this case, the hydrophobic fumed silica having carbon of 0.8 to 5.0, more preferably 1.0 to 3.0% by weight based on the total weight of the filler due to such a treatment agent improves the tear strength. It is preferable because it contributes effectively. Such hydrophobic fumed silica may be commercially available, for example, Aerosil R-976, Aerosil R-974 (manufactured by Nippon Aerosil Co., Ltd.), Aerosil R-812 (manufactured by Degussa), Leolosil DM-30S, Leolosil. DM-20S (manufactured by Tokuyama Corporation) and the like can be mentioned.

  The inorganic filler (F) used in the present invention can be used alone or in combination of two or more kinds from the above filler group, and the inorganic filler (F) represents the total amount of the components (A) and (B). When it is 100 parts by weight, it is preferably used in an amount of 0 to 300 parts by weight. When it exceeds 300 parts by weight, there is a tendency that a problem occurs in terms of moldability.

  The particle size of the hydrosilylated crosslinked product of the component (B) of the thermoplastic elastomer composition of the present invention is preferably 400 μm or less, more preferably 0.1 to 100 μm from the viewpoint of mechanical properties.

  Furthermore, silicone oil such as dimethylpolysiloxane and linear methylphenylpolysiloxane can be added to the thermoplastic elastomer composition of the present invention, and various additives such as pigments and anti-aging can be used depending on the purpose. An agent, a flame retardant, a plasticizer, a winning agent, etc. may be added.

  The thermoplastic elastomer composition of the present invention is a kneader capable of being heated to the melting point or higher of the isobutylene block copolymer of the component (A), such as a roll, a closed kneader (kneader, Banbury mixer, etc.), a single screw extruder. Using a kneading machine such as a twin screw extruder, kneading while heating above the melting point of the isobutylene block copolymer (A) in the presence of the isobutylene block copolymer (A) and the polyorganosiloxane rubber (B). And it can manufacture by bridge | crosslinking (B) component (dynamically bridge | crosslinking). In addition, by performing dynamic crosslinking in this way, the generated polymer network is divided by shearing force and exhibits thermoplasticity even after crosslinking.

  Hereinafter, the present invention will be described in more detail based on examples, but the present invention is not limited by these. Prior to the examples, various measurement methods, evaluation methods, and examples will be described.

(hardness)
In accordance with JIS K6253, a 12.0 mm thick press sheet was used as a test piece, and measurement was performed with a type A durometer.
(Compression set (Cset))
In accordance with JIS K 6262, a 12.0 mm thick press sheet was used as a test piece. The measurement was performed under the conditions of 100 ° C. × 22 hours and 25% deformation.

(Tensile strength)
In accordance with JIS K 6251, a 2 mm-thick press sheet punched into No. 3 with a dumbbell was prepared as a test piece, and this was used for measurement. The tensile speed was 500 mm / min.

(Tensile modulus)
In accordance with JIS K 6251, a 2 mm-thick press sheet punched into No. 3 with a dumbbell was prepared as a test piece, and this was used for measurement. The tensile speed was 500 mm / min. The elastic modulus was calculated based on the stress having a strain of 10% to 20%.

(Tensile elongation)
In accordance with JIS K 6251, a 2 mm-thick press sheet punched into No. 3 with a dumbbell was prepared as a test piece, and this was used for measurement. The tensile speed was 500 mm / min.

(Tear strength)
In accordance with JIS K 6252, a 2 mm thick press sheet punched into an angle shape with a dumbbell was prepared as a test piece, and this was used for measurement. The tearing speed was 500 mm / min.

(Extraction test)
In accordance with the 14th revised Japanese Pharmacopoeia general test method "extracted rubber plug test method", a 1 mm thick press sheet was prepared as a test piece and used for measurement. In the pH, potassium permanganate reducing substance, evaporation residue, and ultraviolet absorption spectrum, all were within the standard, and one was out of the standard.

In addition, the abbreviations and specific contents of materials used in Examples and Comparative Examples are as follows.
Component (A) SIBS: Isobutylene block copolymer (Production Example 1)
Component (C) QR1: Polyorganosiloxane containing organohydrogenpolysiloxane Q7-4750A Dow Corning Co., Ltd. Component (D) QR2: Polyorganosiloxane having at least two alkenyl groups in the molecule Q7-4750B Dow Corning Component (E) Ptcat: 1,1,3,3-tetramethyl-1,3-dialkenyldisiloxane complex of zerovalent platinum, 3 wt% xylene solution component (F) Filler: Silica Nipseal VN3 manufactured by Nippon Silica Co., Ltd. PP: Polypropylene J108M Prime Polymer SEBS: Styrene-Ethylene Butylene-Styrene Block Copolymer G1652 Kraton Polymer Japan

(Production Example 1) [Production of Isobutylene Block Copolymer (SIBS)]
After the inside of the polymerization vessel of the 2 L separable flask was purged with nitrogen, 456.4 mL of n-hexane (dried with molecular sieves) and 656.3 mL of butyl chloride (dried with molecular sieves) were added using a syringe. After the polymerization vessel was cooled in a dry ice / methanol bath at −70 ° C., a Teflon (registered trademark) feeding tube was placed in a pressure-resistant glass liquefied collection tube with a three-way cock containing 232 mL (2871 mmol) of isobutylene monomer. And the isobutylene monomer was fed into the polymerization vessel by nitrogen pressure. 0.647 g (2.8 mmol) of p-dicumyl chloride and 1.22 g (14 mmol) of N, N-dimethylacetamide were added. Next, 8.67 mL (79.1 mmol) of titanium tetrachloride was further added to initiate polymerization. After stirring at the same temperature for 2.5 hours from the start of polymerization, about 1 mL of the polymerization solution was withdrawn from the polymerization solution for sampling, and the degree of polymerization was confirmed. Subsequently, a mixed solution of 77.9 g (748 mmol) of styrene monomer, 14.1 mL of n-hexane and 20.4 mL of butyl chloride, which had been cooled to −70 ° C. in advance, was added to the polymerization vessel. Two hours after adding this 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. The molecular weight of the polymer obtained by the gel permeation chromatography (GPC) method was measured. A block copolymer having a block copolymer Mw of 101,000 was obtained.

Example 1
Laboplast mill (Toyo Seiki Co., Ltd.) set at 170 ° C. in the ratio shown in Table 1 for SIBS as component (A), QR1 as component (C), and QR2 as component (D) manufactured in Production Example 1 Then, Ptcat which is the component (E) was added at a ratio shown in Table 1, and melt-kneaded for 10 minutes to perform dynamic crosslinking. The obtained thermoplastic elastomer composition could be easily formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Example 2)
Components (A), (C), (D), and (E) were mixed in the proportions shown in Table 1, and dynamic crosslinking was performed in the same manner as in Example 1. The obtained thermoplastic elastomer composition could be easily formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Example 3)
Components (A), (C), (D), and (E) were mixed in the proportions shown in Table 1, and dynamic crosslinking was performed in the same manner as in Example 1. The obtained thermoplastic elastomer composition could be easily formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

Example 4
Components (A), (C), (D), and (E) were mixed in the proportions shown in Table 1, and dynamic crosslinking was performed in the same manner as in Example 1. The obtained thermoplastic elastomer composition could be easily formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Example 5)
Components (A), (C), (D), (E), and (F) were mixed in the proportions shown in Table 1, and dynamic crosslinking was performed in the same manner as in Example 1. The obtained thermoplastic elastomer composition could be easily formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 1)
PP, (C) QR1, and (D) QR2 were melt-kneaded for 5 minutes using a lab plast mill (manufactured by Toyo Seiki Co., Ltd.) set at 170 ° C. in the ratios shown in Table 1, and then (E) Ptcat was expressed. The mixture was added at the ratio shown in 1 and melt-kneaded for 10 minutes for dynamic crosslinking. The resulting thermoplastic elastomer composition could be formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 2)
SEBS, QR1 as component (C), QR2 as component (D) at the ratio shown in Table 1, and melt-kneaded for 5 minutes using a Laboplast mill (manufactured by Toyo Seiki Co., Ltd.) set at 170 ° C. The component (E), Ptcat, was added in the ratio shown in Table 1, and melt-kneaded for 10 minutes for dynamic crosslinking. The resulting thermoplastic elastomer composition could be formed into a sheet at 180 ° C. The hardness, tensile test, compression set, and extraction test of the obtained sheet were measured according to the above methods. The results are shown in Table 1.

(Comparative Example 3)
(C) Component QR1 and Component (D2) QR2 in the proportions shown in Table 1 were melt kneaded for 5 minutes using a lab plast mill (manufactured by Toyo Seiki Co., Ltd.) set at 170 ° C., then (E ) Component Ptcat was added in the ratio shown in Table 1, melt kneaded for 10 minutes, and dynamic crosslinking was performed, but the thermoplasticity was lost and it became a powder and became unmoldable.

  In Examples 1-5, the hardness is 44A to 55A and the tensile modulus is 1.54 to 2.16 MPa, which is excellent in flexibility, while in Comparative Examples 1 and 2, the hardness is 75A and the tensile modulus is 4.31 MPa. It was hard and not very flexible. Comparative Example 3 did not show thermoplasticity because it did not contain SIBS.

  In addition, it turns out that it is possible to balance Cset, tensile strength, and tear strength by changing the compounding quantity of component (C) and (D) like Examples 1-4.

As described above, it can be seen that the thermoplastic elastomer composition of the present invention is flexible and excellent in rubber elasticity and hygiene.

Claims (3)

An isobutylene block copolymer comprising an isobutylene block copolymer (A) comprising a polymer block (a) mainly composed of an aromatic vinyl compound and an isobutylene polymer block (b) and a polyorganosiloxane rubber (B). (A) / organosiloxane rubber (B) = 10/90 to 95/5, and the polyorganosiloxane rubber (B) is melt-kneaded with the isobutylene block copolymer (A) and the polyorganosiloxane rubber (B). A thermoplastic elastomer composition obtained by dynamically crosslinking B), wherein the polyorganosiloxane rubber (B) comprises one molecule of polyorganosiloxane (C) containing organohydrogenpolysiloxane. Polyorganosiloxane (D) having at least two alkenyl groups and platinum catalyst (E) And (silicon-bonded hydrogen atom contained in polyorganosiloxane (C)) / (alkenyl group contained in polyorganosiloxane (D)) = 0.5 / 1 to 1 / 0.5 (molar ratio). Thermoplastic elastomer composition.   The thermoplastic elastomer composition according to claim 1, wherein the polyorganosiloxane rubber (B) is crosslinked by a hydrosilylation reaction. The filler (F) is contained in an amount of 0 to 300 parts by weight when the total amount of the isobutylene block copolymer (A) and the polyorganosiloxane rubber (B) is 100 parts by weight. The thermoplastic elastomer composition according to any one of 1 and 2 .