JP2006225581A - Molded product formed out of thermoplastic elastomer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a sound-absorbing and/or vibration-damping molded product formed out of a thermoplastic elastomer composition which scarcely causes oil bleeding, has excellent transparency, flexibility, permanent compression set, and vibration absorption properties, and further has excellent molding processability in injection molding, etc. <P>SOLUTION: This sound-absorbing and/or vibration-damping molded product is formed out of the thermoplastic elastomer composition which contains (a) 100 pts.wt. of a hydrogenated and/or partially hydrogenated block copolymer mixture and (b) 180-400 pts.wt. of a softening agent for a non-aromatic rubber, wherein the block copolymer mixture (a) contains (a-2) 150-500 pts.wt. of a hydrogenated and/or partially hydrogenated block copolymer having a content of an aromatic vinyl compound of less than 40 wt% in (a-1) 100 pts.wt. of a hydrogenated and/or partially hydrogenated block copolymer having a content of the aromatic vinyl compound of 50-70 wt% and has a content of the aromatic vinyl compound of 30-45 wt% based on a total amount of the hydrogenated and/or partially hydrogenated block copolymers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a sound-absorbing and / or vibration-damping molded article comprising a thermoplastic elastomer composition, and in particular, transparency, flexibility, compression set, vibration absorption, low oil bleed and excellent moldability. The present invention relates to a sound-absorbing and / or vibration-damping molded article comprising a thermoplastic elastomer composition excellent in impact absorption.

  Conventionally, a thermoplastic elastomer resin composition having a predetermined hardness has been obtained by adding oil as a softening agent and olefin resin as a resin component to a styrene resin composition or an ethylene-propylene resin composition, Paraffin oil is often used as the oil. However, the addition of oil makes it possible to reduce the hardness, but since a resin having a lower molecular weight than other resin components is used, heat resistance, weather resistance, mechanical strength, wear resistance, etc. are reduced. .

  In addition, when obtaining a very soft thermoplastic resin composition, there is a problem that oil bleeding occurs on the surface of the molded product, and a satisfactory thermoplastic resin composition cannot be obtained. That is, in general, the amount of oil that can be absorbed by the thermoplastic resin composition has an upper limit of oil amount / thermoplastic resin composition = a little more than three times, and when more oil is added, oil bleeding occurs. Moreover, if the oil amount / thermoplastic resin composition amount = more than three times the upper limit, pelletization becomes difficult. Further, when transparency is required, the combination of the thermoplastic resins to be added is considerably limited, and it becomes difficult to adjust the balance between the molding processability and various physical properties.

  Furthermore, a composition composed of styrene-based thermoplastic elastomers and paraffins has been disclosed as a gel elastomer (see, for example, Patent Document 1), but a high temperature is required during production and heat dissolution. For this reason, there is also a problem that the paraffins ooze out and feel oily because the gel is browned and solidified immediately when molded, the handling property is insufficient and difficult to handle, and the structural strength of the gel is insufficient. It was.

  In order to solve the above problems, isopropyl myristate, isopropyl palmitate, butyl stearate, and isononyl isononanoate are blended to lower the melting temperature of styrenic thermoplastic elastomers. An invention has been disclosed in which the nature is increased and the feel is refreshed (see, for example, Patent Document 2). However, although the effect of improving the hue is sufficiently exerted, the oiliness is still strong, and the improvement of oiliness is insufficient particularly in the field where a refreshing feel such as foot care use is required.

In order to improve such oily feeling, etc., the effect of addition of fatty acid esters was studied, and the size of the alkyl group existing between the ester groups and the ratio of branching influence the effect of adding the fatty acid ester. A gel elastomer composition composed of styrene-based thermoplastic elastomers, paraffins, and fatty acid esters (cetyl 2-ethylhexylate) has been proposed (for example, see Patent Document 3). Furthermore, as a gel-like composition imparted with shock absorbing performance, a gel-like composition obtained by swelling a triblock styrene elastomer in a softening agent (see, for example, Patent Document 4), a triblock styrene elastomer and diblock A gel-like composition (for example, see Patent Documents 5 and 6) composed of a type styrene elastomer and a softening agent has been proposed. However, these gel compositions also have a problem that the balance of transparency, oil bleed, and moldability is remarkably inferior.
Further, in all the above prior arts, particularly in the case of injection molding, the cooling time is abnormally long, and in some cases, there are cases where the cooling time is about 25 minutes, and the productivity is remarkably inferior.

  Therefore, the present inventors have a softening agent for non-aromatic hydrocarbon rubber as a super-soft composition which is rich in flexibility, excellent in heat distortion characteristics, mechanical strength, oil resistance and molding processability and has no stickiness, Compositions containing organic peroxides, crosslinking aids, thermoplastic resins as optional components (see, for example, Patent Document 7), styrenic thermoplastic elastomers, softeners for non-aromatic hydrocarbon rubbers, vinyl aromatic resins , A hydrogenated petroleum resin, an acrylic processing aid, and a composition containing an organic peroxide (see, for example, Patent Document 8), easy handling, no oil bleed, and excellent mechanical strength As a thermoplastic gel composition having wear resistance, a thermoplastic resin containing a softener for non-aromatic hydrocarbon rubber, a hydrogenated styrene thermoplastic elastomer, and an amorphous polyolefin. Sex gel composition (for example, see Patent Document 9.) Have proposed. However, a thermoplastic elastomer composition excellent in transparency and molding processability and excellent in balance between molding processability and various physical properties has not been obtained.

  Furthermore, attempts have been made to improve styrenic thermoplastic elastomers using an adhesive resin such as petroleum resin. For example, a pressure-sensitive adhesive composition in which a tackifier such as a terpene resin is blended with a partially hydrogenated block copolymer in which a conjugated diene moiety is partially hydrogenated (see, for example, Patent Document 10), a styrene block. A hot melt pressure-sensitive adhesive composition in which an aromatic petroleum resin obtained by petroleum decomposition is blended with a copolymer (see, for example, Patent Document 11), and a tackifier having a styrene block copolymer made of a petroleum resin or the like. A hot-melt adhesive (for example, see Patent Document 12), a pressure-sensitive adhesive composition in which an aliphatic or alicyclic adhesive resin or the like is blended with a styrene block copolymer (for example, see Patent Document 13). ), Stretch film for food packaging made of hydrogenated styrene block copolymer, petroleum resin, polypropylene resin (see, for example, Patent Documents 14 to 16). There has been disclosed. However, all of the techniques described in these patent documents merely use tackifying properties such as petroleum resins, have few oil bleeds, have excellent mechanical strength, transparency, flexibility, and moldability. An elastomer resin composition excellent in the above was not disclosed.

In addition, in electronic devices such as hard disk drives, disk-shaped recording medium playback devices, and devices with built-in microphones, they are made of a low-hardness rubber-like elastic body that has high shock absorption and vibration absorption for measures against dropping impact and vibration. There is a need for molded bodies. However, many conventional low-hardness thermoplastic elastomers have poor mechanical strength, compression set, moldability, and the like, and are difficult to use for the above applications.
US Pat. No. 4,369,284 US Pat. No. 5,558,872 JP 2000-281850 A JP-A-8-73696 JP 2001-151979 A JP 2001-151980 A JP 2001-311012 A JP 2000-34389 A JP 2003-183506 A JP-A-6-145626 JP-A-6-271826 JP-A-8-283865 Japanese Patent Publication No. 7-5873 JP-A-9-156665 Japanese Patent Laid-Open No. 9-165491 JP-A-9-165492

  In view of the above problems, the present invention has few oil bleeds, excellent transparency, flexibility, compression set, vibration absorption, shock absorption, and further has molding processability such as injection molding. An object of the present invention is to provide a molded article for sound absorption and / or vibration damping using a thermoplastic elastomer composition having excellent transparency and flexibility.

  As a result of intensive studies to solve the above-mentioned problems, the present inventors have applied hydrogenated and / or partially hydrogenated block copolymer mixtures having two specific aromatic vinyl compound contents to non-aromatic rubbers. By adding a softener and blending petroleum resin and terpene oil as necessary, heat treatment can be performed to supply pellets, various molding processes are possible, transparent, no oil bleed, especially compression A thermoplastic elastomer composition which is an elastic body excellent in permanent strain, vibration absorption, and shock absorption is obtained, and a molded body from the thermoplastic elastomer composition is found to have excellent sound absorption and vibration damping properties. The invention has been completed.

That is, according to the first aspect of the present invention, (a) 100 parts by weight of a hydrogenated and / or partially hydrogenated block copolymer mixture having an aromatic vinyl compound content of 30 to 45% by weight (provided that (A) is (a-1) (a-2) an aromatic vinyl compound with respect to 100 parts by weight of a hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of 50 to 70% by weight. Containing 150 to 500 parts by weight of a hydrogenated and / or partially hydrogenated block copolymer with a content of less than 40% by weight.), And (b) containing 180 to 400 parts by weight of a non-aromatic rubber softener. There is provided a molded article for sound absorption and / or vibration damping, characterized by comprising a thermoplastic elastomer composition.

  According to a second invention of the present invention, in the first invention, (c) a thermoplastic elastomer composition further comprising 1 to 40 parts by weight of a petroleum resin, and / or for sound absorption, A molded body for damping is provided.

  According to a third invention of the present invention, in the first or second invention, (d) a thermoplastic elastomer composition further containing 1 to 60 parts by weight of a terpene oil, and for sound absorption And / or a molded body for vibration damping is provided.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the molding is used for shock buffering or vibration isolation in a hard disk drive or a disk-shaped recording medium playback device. The body is provided.

  According to a fifth aspect of the present invention, there is provided a molded body characterized in that it is used for a microphone holder in any one of the first to third aspects.

  The thermoplastic elastomer composition used in the present invention has less oil bleed, has excellent transparency, compression set, vibration absorption, and excellent molding processability such as injection molding. Further, since it has less oil bleed and has excellent transparency, compression set, vibration absorption and shock absorption, it can be used as a molded article having sound absorption and vibration damping properties.

The constituents of the thermoplastic elastomer composition, the method for producing the composition, the molded product obtained from the composition, and its use will be described in detail below as a raw material for the molded product of the present invention.
1. Component (a) Hydrogenated and / or Partially Hydrogenated Block Copolymer Mixture of Thermoplastic Elastomer Composition The hydrogenated and / or partially hydrogenated block copolymer mixture used in the thermoplastic elastomer composition of the present invention is aromatic. Hydrogenated and / or partially hydrogenated block copolymer mixture having an aromatic vinyl compound content of 30 to 45% by weight, wherein (a-1) hydrogenated aromatic vinyl compound content is 50 to 70% by weight And / or a mixture of a partially hydrogenated block copolymer and (a-2) a hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of less than 40% by weight.
Component (a) not only exhibits rubber elasticity and mechanical properties, but also improves the oil absorption efficiency of (b) the softener for non-aromatic rubber during compounding, and improves dispersibility and meltability during melt-kneading. . As a result, the moldability is improved and the transparency of the obtained product is improved.

The hydrogenated and / or partially hydrogenated block copolymer of (a-1) or (a-2) is mainly composed of at least one polymer block A mainly composed of an aromatic vinyl compound and a conjugated diene compound. And a hydrogenated block copolymer obtained by hydrogenating a block copolymer comprising at least one polymer block B.
A block comprising at least one polymer block A mainly composed of an aromatic vinyl compound and at least one polymer block B mainly composed of a conjugated diene compound that can be used in the thermoplastic elastomer composition of the present invention. The hydrogenated block copolymer component obtained by hydrogenating the copolymer contains at least one polymer block A mainly composed of an aromatic vinyl compound and at least one polymer block B mainly composed of a conjugated diene compound. It is a polymer obtained by hydrogenating one block copolymer. For example, a hydrogenated block copolymer of an aromatic vinyl compound-conjugated diene compound having a structure such as A-B, A-B-A, B-A-B-A, or A-B-A-B-A Is obtained.

  The polymer block A mainly composed of an aromatic vinyl compound may be a polymer composed only of an aromatic vinyl compound or a copolymer of an aromatic vinyl compound and less than 50% by weight of a conjugated diene compound. The polymer block B mainly composed of a conjugated diene compound may be a polymer composed solely of a conjugated diene compound or a copolymer of a conjugated diene compound and less than 50% by weight of an aromatic vinyl compound.

  As the aromatic vinyl compound constituting the hydrogenated block copolymer, for example, one or more kinds can be selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, etc. Styrene is preferred. In addition, as the conjugated diene compound, for example, one or two or more kinds are selected from butadiene, isoprene, 1,3-pentadiene, 2,3-dimethyl-1,3-butadiene, etc., among which butadiene, isoprene and These combinations are preferred.

  Hydrogenated block obtained by hydrogenating a block copolymer comprising at least one polymer block A mainly composed of an aromatic vinyl compound and at least one polymer block B mainly composed of a conjugated diene compound In the polymer block B mainly composed of a conjugated diene compound, the hydrogenation rate of the polymer component is arbitrary, but it is preferably 50% or more, more preferably 55% or more, and still more preferably 60% or more. Further, the microstructure is arbitrary. For example, when the block B is composed of butadiene alone, the polybutadiene block preferably has a 1,2-microstructure of 20 to 50% by weight, particularly preferably 25 to 45%. % By weight. Moreover, the thing which hydrogenated the 1, 2- bond selectively may be sufficient. When block B is composed of a mixture of isoprene and butadiene, the 1,2-microstructure is preferably less than 50%, more preferably less than 25%, and even more preferably less than 15%.

  When block B is composed of isoprene alone, in the polyisoprene block, preferably 70 to 100% by weight of isoprene has a 1,4-microstructure, and preferably at least aliphatic double bonds derived from isoprene. 90% hydrogenated is preferred.

  When a hydrogenated block copolymer is used depending on the application, the above hydrogenated product can be suitably used according to the application.

  The weight average molecular weight of the whole hydrogenated and / or partially hydrogenated block copolymer component is 100,000 to 350,000, preferably 30,000 to 250,000. If the weight average molecular weight exceeds 350,000, the moldability deteriorates. On the other hand, when the weight average molecular weight is less than 100,000, compression set is deteriorated.

  Specific examples of the hydrogenated and / or partially hydrogenated block copolymer include styrene-ethylene-butene copolymer (SEB), styrene-ethylene-propylene copolymer (SEP), styrene-ethylene-butene-styrene copolymer. Polymer (SEBS), Styrene-ethylene / propylene-styrene copolymer (SEPS), Styrene-ethylene / ethylene / propylene / styrene copolymer (SEEPS), Styrene / butadiene / butylene / styrene copolymer (partially hydrogenated) Styrene-butadiene-styrene copolymer (SBBS), partially hydrogenated styrene-isoprene-styrene copolymer, partially hydrogenated styrene-isoprene / butadiene-styrene copolymer, and the like. In the present invention, the hydrogenated product of the aromatic vinyl compound-conjugated diene compound block copolymer may be used alone or in combination of two or more.

  A block obtained by hydrogenating a block copolymer comprising at least one polymer block A mainly composed of these aromatic vinyl compounds and at least one polymer block B mainly composed of a conjugated diene compound. As a method for producing a copolymer, a number of methods have been proposed. As a typical method, for example, a lithium catalyst or a Ziegler type catalyst is used by the method described in JP-B-40-23798. It can be obtained by block polymerization in an inert medium. Such a hydrogenation treatment of the block copolymer can be performed by a known method in the presence of a hydrogenation catalyst in an inert solvent.

  The aromatic vinyl compound content in the component (a) used in the present invention is 30 to 45% by weight, preferably 35 to 45% by weight. When the aromatic vinyl compound content of the total component (a) exceeds 45% by weight, the transparency and flexibility are deteriorated, and the gate breakage during injection molding is liable to occur. Worsens, and the cooling time during injection molding also becomes longer.

  The hydrogenated and / or partially hydrogenated block copolymer (a-1) used in the component (a) has an aromatic vinyl compound content of 50 to 70% by weight, preferably 60 to 70% by weight. It is. If the aromatic vinyl compound content exceeds the above upper limit value, the softening agent tends to bleed out, and the flexibility and moldability of the final product also deteriorate, and if it is less than the lower limit, the moldability deteriorates.

The hydrogenated and / or partially hydrogenated block copolymer (a-2) used in the component (a) has an aromatic vinyl compound content of less than 40% by weight, preferably 30% by weight or more. , Less than 40% by weight.
Hydrogenated and / or partially hydrogenated block copolymers having an aromatic vinyl compound content of less than 40% by weight not only exhibit rubber elasticity and mechanical properties, but also (b) soften for non-aromatic rubber during compounding It has the effect of improving the oil absorption efficiency of the agent and improving the flexibility and transparency of the product obtained.

  In the present invention, the composition ratio of the two types of block copolymers in the component (a) is such that (a-1) hydrogenated and / or partially hydrogenated block copolymers having an aromatic vinyl compound content of 50 to 70% by weight. (A-2) The hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of less than 40% by weight is 150 to 500 parts by weight, preferably 180 parts per 100 parts by weight of the polymer. -400 parts by weight. (A-2) When the hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of less than 40% by weight exceeds 500 parts by weight, the cooling time at the time of injection molding becomes long, and less than 150 parts by weight. If this is the case, the transparency deteriorates, and a gate breakage failure occurs during injection molding.

  In addition, a hydrogenated conjugated diene block copolymer may be used as the (a-2) hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of less than 40% by weight. Examples of the hydrogenated conjugated diene block copolymer include a block copolymer (CEBC) having a crystalline ethylene block and an amorphous ethylene-butene block obtained by hydrogenating a block copolymer of butadiene. Is mentioned. The weight average molecular weight of the hydrogenated product of the conjugated diene block copolymer is preferably 100,000 to 350,000, and more preferably 130,000 to 250,000. When the weight average molecular weight exceeds 350,000, the moldability deteriorates, and when it falls below 100,000, the compression set deteriorates.

(B) Non-aromatic rubber softener The non-aromatic hydrocarbon rubber softener (b) used in the thermoplastic elastomer composition of the present invention has a function of adjusting the hardness of the resulting composition and moldability. It is a component that fulfills the function of improvement.
A composition that is particularly flexible and excellent in transparency by adding a large amount of the component (b) of 180 to 400 parts by weight to the component (a) as compared with the composition found in the prior art such as food packaging films. Can be obtained.
Examples of the component (b) include non-aromatic mineral oils or liquid or low molecular weight synthetic softeners. Generally, a mineral oil softener for rubber is a mixture of an aromatic ring, a naphthene ring and a paraffin chain, and has a saturated hydrocarbon chain carbon number of 50% or more of the total carbon number. Those that occupy 30 to 40% are called naphthenes, and those that occupy 30% or more aromatic carbons are called aromatics. The mineral oil softener for rubber used in the present invention is preferably the paraffinic and naphthenic types described above. Aromatic softeners are not preferred because of their poor dispersibility.
As the non-aromatic hydrocarbon rubber softening agent, a paraffinic mineral oil softening agent is particularly preferable, and paraffinic ones having a small aromatic ring component are particularly suitable.

  Examples of the compound constituting the paraffinic softener include paraffinic compounds having 4 to 155 carbon atoms, preferably paraffinic compounds having 4 to 50 carbon atoms, and specifically, butane, pentane, hexane. , Heptane, octane, nonane, decane, undecane, dodecane, tetradecane, pentadecane, hexadecane, heptadecane, octadecane, nonadecane, eicosan, heneicosan, docosan, tricosan, tetracosan, pentacosan, hexacosan, heptacosan, octacosan, triacotan, henakosan, triacontane, N-paraffins (linear saturated hydrocarbons) such as Contan, Dotriacontane, Pentatriacontane, Hexacontane, Heptacontane, etc., Isobutane, Isopentane, Neopentane, Isohexane, Pentane, neohexane, 2,3-dimethylbutane, 2-methylhexane, 3-methylhexane, 3-ethylpentane, 2,2-dimethylpentane, 2,3-dimethylpentane, 2,4-dimethylpentane, 3, 3-dimethylpentane, 2,2,3-trimethylbutane, 3-methylheptane, 2,2-dimethylhexane, 2,3-dimethylhexane, 2,4-dimethylhexane, 2,5-dimethylhexane, 3,4 -Dimethylhexane, 2,2,3-trimethylpentane, isooctane, 2,3,4-trimethylpentane, 2,3,3-trimethylpentane, 2,3,4-trimethylpentane, isononane, 2-methylnonane, isodecane, Isoundecane, isododecane, isotridecane, isotetradecane, isopentadecane, isoeo Tadekan, Isonanodekan, isoeicosane, 4-ethyl-5-isoparaffins methyl octane (branched saturated hydrocarbons) and can include derivatives of these saturated hydrocarbons. These paraffins are used in a mixture and are preferably liquid at room temperature.

  Commercially available paraffinic softeners that are liquid at room temperature include NA Solvent (isoparaffinic hydrocarbon oil) manufactured by Nippon Oil & Fats, PW-90 (n-paraffinic process oil) manufactured by Idemitsu Kosan Co., Ltd., and Idemitsu. Examples thereof include IP-solvent 2835 (synthetic isoparaffinic hydrocarbon, 99.8 wt% or more isoparaffin) manufactured by Petrochemical Co., Ltd., neothiozole (n-paraffinic process oil) manufactured by Sanko Chemical Co., Ltd., and the like.

  Moreover, a small amount of unsaturated hydrocarbons and derivatives thereof may coexist in the non-aromatic hydrocarbon softener. Unsaturated hydrocarbons include ethylene, propylene, 1-butene, 2-butene, isobutylene, 1-pentene, 2-pentene, 3-methyl-1-butene, 3-methyl-1-butene, 2-methyl-2 -Ethylene hydrocarbons such as butene, 1-hexene, 2,3-dimethyl-2-butene, 1-heptene, 1-octene, 1-nonene, 1-decene, acetylene, methylacetylene, 1-butyne, 2- Examples thereof include acetylene hydrocarbons such as butyne, 1-pentyne, 1-hexyne, 1-octyne, 1-nonine and 1-decyne.

  The compounding quantity of a component (b) is 180-400 weight part with respect to 100 weight part of component (a), Preferably it is 200-350 weight part. When the blending amount of component (b) exceeds the above upper limit, the tackiness of the final product becomes prominent, gate failure during injection molding and cooling time during molding become longer, and flexibility and transparency below the lower limit. The fluidity at the time of injection molding is lowered, and the appearance of the product is deteriorated.

(C) Petroleum resin In the thermoplastic elastomer composition of the present invention, a petroleum resin (c) can be used as necessary. Component (c) is a component that functions to impart further flexibility and yellowness to the resulting composition, and to provide a more balanced flexibility and texture.
Flexibility can be imparted to the component (a) by adding a large amount of the component (b), but there are problems such as bleed and manufacturability, and pellet supply is difficult. The component (c) can provide flexibility without increasing the amount of the component (b) added, and further contributes to the improvement of transparency.
Component (c) is a resin obtained by copolymerizing an unsaturated hydrocarbon obtained in various processes of the petroleum refining industry and petrochemical industry, particularly a naphtha decomposition process, and using a C5 fraction as a raw material. Aliphatic petroleum resin, aromatic petroleum resin made from C9 fraction, alicyclic petroleum resin made from dicyclopentadiene, terpene resin, and copolymerization system of these two or more Examples thereof include petroleum resins and hydrogenated petroleum resins obtained by hydrogenating these. The hydrogenated petroleum resin of the above-described resin can be obtained by hydrogenating the above resin by a method known to those skilled in the art. Specifically, Imabe (hydrogenated petroleum resin) manufactured by Idemitsu Petrochemical Co., Ltd., Alcon (hydrogenated petroleum resin) manufactured by Arakawa Chemical Industries, Ltd., and Clearon (hydrogenated terpene resin) manufactured by Yashara Chemical Co., Ltd. Commercial products such as Escorez (aliphatic hydrocarbon resin) manufactured by Tonex Co., Ltd. can be used.

  When blended, the amount of component (c) is preferably 1 to 40 parts by weight, more preferably 5 to 30 parts by weight, per 100 parts by weight of component (a). When the blending amount of component (c) exceeds the above upper limit, the tackiness of the final product becomes prominent, gate failure during injection molding and cooling time during molding become longer, and flexibility and transparency below the lower limit. There is no improvement effect.

(D) Terpene oil In the thermoplastic elastomer composition of the present invention, a terpene oil (d) can be used as necessary. The terpene oil (d) has a function of improving the bleed resistance, transparency, flexibility and moldability of the resulting composition.
In particular, the component (d) has a function of suppressing bleeding when the components (b) and (c) are contained in a large amount relative to the component (a).
Ingredient (d) includes essential oils obtained by steam distillation of raw pine fat collected from red pine and black pine stands mainly in North America and mainland China, turpentine oil, a by-product of pulp production of the tree, or orange Specific examples include terpene hydrocarbons and terpene ethers having 10 carbon atoms, which are obtained from essential oils extracted from hides or orange oils derived from these essential oils by isomerization reaction or the like.

  Terpene hydrocarbons having 10 carbon atoms include myrcene (boiling point 167 ° C.), karene (boiling point 167 ° C.), osymene, pinene (boiling point 155 ° C.), limonene (boiling point 176 ° C.), camphene (boiling point 160 ° C.), terpinolene. (Boiling point 187 ° C.), tricyclene (boiling point 153 ° C.), terpinene (boiling point 170-180 ° C.), fenchen (boiling point 150-155 ° C.), ferrandrene (boiling point 170-175 ° C.), silbestrene (boiling point 175 ° C.), Sabinene (boiling point 163 ° C.), P-menten-1 (carbomentene) (boiling point 176 ° C.), P-menten-3 (boiling point 168 ° C.), P-cymene, P-menthane (boiling point 168 ° C.) and the like. Of these, α-pinene, β-pinene, limonene, P-menten-1, P-menten-3, P-cymene, and P-menthane are particularly preferable.

  Examples of the terpene ether having 10 carbon atoms include 1,4-cineole (boiling point 173 ° C.), 1,8-cineole (boiling point 173 ° C.), pinol (boiling point 180 ° C.), and the like. Among these, at least one selected from 1,4-cineole and 1,8-cineole is particularly preferable.

  When blended, the amount of component (d) is 1 to 60 parts by weight, preferably 5 to 20 parts by weight, per 100 parts by weight of component (a). If the blending amount of component (d) exceeds the above upper limit value, the bleed resistance of the final product deteriorates, the gate breakage failure during injection molding and the cooling time during molding become longer. Moreover, if it is less than the said minimum, there will be no fluidity improvement effect at the time of injection molding.

(E) Other components The thermoplastic elastomer composition of the present invention includes a heat stabilizer, an antioxidant, a light stabilizer, an ultraviolet absorber, a crystal nucleating agent, and an antiblocking agent as long as the object of the present invention is not impaired. , Sealants, mold release agents such as stearic acid and silicone oil, lubricants such as polyethylene wax, colorants, pigments, inorganic fillers (alumina, talc, calcium carbonate, mica, wollastonite, clay), foaming agents (Organic or inorganic), flame retardant (hydrated compound, red phosphorus, ammonium polyphosphate, antimony, silicone) and the like can be blended.
Examples of the antioxidant include 2,6-di-tert-p-butyl-p-cresol, 2,6-di-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol, 4,4- Examples thereof include phenolic antioxidants such as dihydroxydiphenyl and tris (2-methyl-4-hydroxy-5-tert-butylphenyl) butane, phosphite antioxidants, thioether antioxidants, and the like. Of these, phenolic antioxidants and phosphite antioxidants are particularly preferred.
Further, as the foaming agent, EXPANSEL (manufactured by EXPANSEL), which is a thermally expandable microcapsule having a vinylidene chloride / acrylonitrile copolymer as an outer shell and encapsulating isobutane is preferable.

2. Production of Thermoplastic Elastomer Composition The thermoplastic elastomer composition of the present invention is prepared by adding the above components (a) to (b), or components (c) to (e) as necessary, and simultaneously or simultaneously It can be manufactured by adding and kneading in any order.

  The method of melt kneading is not particularly limited, and generally known methods can be used. For example, a single screw extruder, a twin screw extruder, a roll, a Banbury mixer, or various kneaders can be used. For example, the above operation can be continuously performed by using a suitable L / D twin screw extruder, Banbury mixer, pressure kneader, or the like. Here, the temperature of the melt kneading is preferably 140 to 200 ° C.

  The thermoplastic elastomer composition of the present invention is transparent, excellent in compression set, vibration absorption, is free of oil bleed, is a very soft elastic body, and can be supplied with pellets. Molding by various molding processes using known molding methods is possible.

3. Molded body made of thermoplastic elastomer composition The molded body made of the thermoplastic elastomer composition of the present invention has few oil bleeds and has excellent flexibility, compression set, high shock absorption and vibration absorption. In addition, it can be used as a drop impact countermeasure or a vibration countermeasure in electronic equipment. In particular, since a molded article made of the thermoplastic elastomer composition of the present invention is excellent in flexibility, it can be used for vibration isolation in a disk-shaped recording medium reproducing apparatus.

  In addition, since the molded article made of the thermoplastic elastomer composition of the present invention is excellent in impact absorption, it can be used as an impact buffer for a hard disk drive. The molded article has A hardness (value after 15 seconds) in JIS K 7312. Is preferably less than 10. In the case of 10 or more, the spring constant increases and the buffering effect decreases. Furthermore, it is preferable that the C hardness (value after 15 seconds) in JIS K 7312 is 5 or more. If it is less than 5, the spring constant is too low, and it may be crushed by impact, and the hard disk drive may collide with the casing and be damaged.

  When used as an impact buffer for a hard disk drive, the thickness of the molded body is preferably 0.3 mm to 5.0 mm. If it is less than 0.3 mm, the impact cannot be absorbed sufficiently, and the hard disk drive may come into contact with the housing and break. On the other hand, when the thickness of the molded body exceeds 5.0 mm, the molded body becomes large, which hinders downsizing of electronic devices. Furthermore, the contact area of the molded body with respect to the hard disk drive is preferably 10% or more. If it is less than 10%, the hard disk drive may come into contact with the casing and be damaged.

  In addition, since the molded article made of the thermoplastic elastomer composition of the present invention is excellent in flexibility and vibration absorption, it can be used as a microphone holder. In this case, it is preferable that the A hardness (value after 15 seconds) in JIS K 7312 is less than 10. If it is less than 10, vibration noise generated from other parts can be blocked. Furthermore, since it is excellent in flexibility, it is easy to insert the microphone into the holder. Furthermore, since it is excellent in transparency, it is easy to inspect for contamination of the holder or the like with a microphone inserted.

  Hereinafter, although an example and a comparative example explain the present invention further, the present invention is not limited to this. In addition, the evaluation method and the used material in an Example are shown below.

1. Evaluation Method of Thermoplastic Elastomer Composition and Its Molded Body (1) Specific gravity: In accordance with JIS K 7112, the test piece was measured using a 1 mm thick press sheet.
(2) Hardness: Measured according to JIS K 7312. The test piece was measured by C hardness (value after 15 seconds) or A hardness (value after 15 seconds) using one or two 6.3 mm thick press sheets.
(3) Vibration absorption (tan δ): Using SII (Seiko Instruments) DMS6100, tan δ at a temperature of 30 ° C. and a frequency of 100 Hz is measured in the tension sine wave mode. did. As a test piece, a 1 mm thick press sheet was used by punching it into a thickness of 10 mm × 40 mm × 1 mm with a dumbbell.
(4) Compression set: conformed to JIS K 6262. The test piece used was a 6.3 mm thick press sheet, and the distortion after 70 ° C. × 22 hours was measured.
(5) Volume change rate: In accordance with JIS K 6258, the test piece was a 1 mm thick press sheet punched into No. 3 with a dumbbell and used. Using IRM # 901 oil, volume change at 70 ° C. × 24 hours was measured.
(6) Heat-resistant deformation: The test piece was a 1 mm thick press sheet, the appearance after 100 ° C. × 72 hours was visually observed, and evaluated according to the following criteria.
○: Neither deformation nor cracking occurs.
Δ: There is no crack, but it is slightly deformed.
X: Significant deformation or cracking occurs.
(7) Transparency: A newspaper with a 10 mm thick sheet of 130 x 160 x 5 mm thick sheets obtained by hot pressing at 180 ° C, preheating 4 minutes / pressurization 2 minutes, pressure 50 kg / cm ² The extent to which small characters could be read was visually observed and evaluated according to the following criteria.
○: Vividly readable.
Δ: Although it is unclear, it can be read somehow.
X: Unclear and unreadable.
(8) Oil bleed / tackiness: A sheet of 130 × 160 × 2 mm thickness obtained by hot pressing at 180 ° C., preheating 2 minutes / pressurization 2 minutes, pressure 50 kg / cm ² is sandwiched between kraft paper, diameter 70 mm The weight of a disk-shaped 500 g was placed, the state of the kraft paper after standing for 168 hours at room temperature (23 ° C.) was visually observed, and evaluated according to the following criteria.
○: Kraft paper is easily peeled off from the sheet and no trace of oil bleed is observed.
(Triangle | delta): Kraft paper slightly adheres to a sheet | seat and the trace of oil bleed is recognized slightly.
X: Kraft paper adheres to the sheet, and traces of oil bleed are observed.
(9) Injection moldability: A sheet of 130 mm × 130 mm × 2 mm was injection molded, the appearance was visually observed, and the presence or absence of flow marks and sink marks was evaluated according to the following criteria.
○: Good Δ: Slightly bad ×: Bad (10) Impact absorption: The impact test of the molded body was conducted at a temperature of 25 ° C. using an impact tester ASQ-500 manufactured by Yoshida Seiki Co., Ltd.
As the test molded body, a plate-shaped molded body having a size of 100 mm × 10 mm and a thickness of 2 mm was used. Two sheets were bonded to the upper surface of the hard disk drive and two sheets were bonded to the lower surface, and placed on the impact table of the test apparatus. If the maximum peak acceleration applied to the impact table is input acceleration, the maximum peak acceleration applied to the hard disk drive is response acceleration, and the input acceleration is fixed to 2000G, and (response acceleration / input acceleration) is less than 1, It was judged that “it is excellent in shock absorption”. For comparison, the same test was performed and evaluated for rubber-like elastic bodies of A hardness 30 silicone rubber, butyl rubber, and the material of Comparative Example 3.
(11) Anti-vibration characteristics: vibration of the molded body of this example used in an optical disc apparatus at a temperature of 25 ° C. using a vibration test apparatus system VS-200-2 (vibration generator VE-200) manufactured by IMV Corporation. A transmission test was performed.
As the test compact, a bush type damper having a cylindrical shape with an outer diameter of 11 mm, an inner diameter of 3 mm and a height of 9 mm and having a mounting groove with a width of 3 mm and a depth of 2 mm at the center of the outer diameter was used. Using the four dampers, a mechanical chassis having an optical disk rotation mechanism and a reading mechanism was supported horizontally in the optical disk apparatus, and the optical disk apparatus was fixed on a vibration table of a vibration generator. The vibration transmissibility (resonance magnification and resonance frequency) to the mechanical chassis when the vibration table is vibrated in the vertical direction or the horizontal direction with respect to the optical disk plane within an acceleration range of 5 m / s ² and a frequency of 10 to 500 Hz. It was measured. The resonance magnification is obtained by measuring the vibration output acceleration a ₂ from the mechanical chassis with respect to the vibration input acceleration a ₁ from the vibration table at the resonance frequency, and converting it by a relational expression of ₂₀ Log (a ₂ / a ₁ ). It was.

2. Sample (a-1-1) hydrogenated block copolymer used in Examples and Comparative Examples: Septon 2104 (SEPS) (trademark; manufactured by Kuraray Co., Ltd.), styrene content 65% by weight, number average molecular weight 70,000 , Weight average molecular weight 91,000, molecular weight distribution 1.30, hydrogenation rate 90% or more (a-2-1) hydrogenated block copolymer: Septon 2005 (SEEPS) (trademark; manufactured by Kuraray Co., Ltd.), containing styrene 20% by weight, number average molecular weight 210,000, weight average molecular weight 250,000, molecular weight distribution 1.19, hydrogenation rate 90% or more (a-2-2) hydrogenated block copolymer: Kraton E-1818E ( SEBS) (trademark; manufactured by Kraton Polymer Japan Ltd.), styrene content 30% by weight, number average molecular weight 160,000, weight average molecular weight 200,000 Molecular weight distribution 1.25, hydrogenation rate 90% or more (a-2-3) hydrogenated block copolymer: Dynalon DR6210B (CEBC) (trademark; manufactured by JSR Corporation), styrene content 0% by weight, number average molecular weight 180,000, weight average molecular weight 230,000, molecular weight distribution 1.27, hydrogenation rate 90% or more (b) Non-aromatic rubber softener: Diana Process Oil PW-90 (manufactured by Idemitsu Kosan Co., Ltd.) Specific gravity: 0.872, type: paraffinic hydrocarbon oil, viscosity (40 ° C.): 95.5 cSt, flash point: 270 ° C., average molecular weight: 539
(C) Petroleum resin: Imabe P-140 (trademark; manufactured by Idemitsu Petrochemical Co., Ltd.)), softening point: 140 ° C., average molecular weight: 910, density: 1.03
(D) Terpene oil: Woody River # 10 (manufactured by Yasuhara Chemical Co., Ltd.) Specific gravity: 0.80, viscosity (25 ° C.): 1.14 cP, boiling point: 167-170 ° C., flash point: 41.5 ° C.
(E) Hindered phenol / phosphite / lactone composite antioxidant: HP2215 (manufactured by Ciba Specialty Chemicals)

(Examples 1-4, Comparative Examples 1-4)
The mixture was put into a twin screw extruder having an L / D of 47 with the component ratios shown in Tables 1 and 2, and melt-kneaded at a kneading temperature of 180 ° C. and a screw rotation speed of 350 rpm to form pellets. Next, the obtained pellet was injection-molded to prepare a test piece, which was used for each test. The evaluation results are shown in Tables 1 and 2.
Next, a molded article for test was molded from the obtained thermoplastic elastomer composition, and an impact test and a vibration transmission test of the molded article were performed and evaluated. The evaluation results are shown in Tables 3 and 4. For reference, the evaluation results of silicone rubber and butyl rubber test molded bodies are also shown.

As is clear from Tables 1 to 4, the thermoplastic elastomer composition of the present invention had good characteristics (Examples 1 to 4).
On the other hand, in Comparative Examples 1 and 2, the aromatic vinyl compound content is 100 parts by weight of hydrogenated and / or partially hydrogenated block copolymer having an aromatic vinyl compound content of component (a) of 50 to 70% by weight. The amount of hydrogenated and / or partially hydrogenated block copolymer of less than 40% by weight is out of the range of 150 to 500 parts by weight, and the aromatic vinyl compound content in the mixture is out of the range of 30 to 45% by weight. It is what. If the content of the aromatic vinyl compound in the component (a) is large, the transparency and flexibility are deteriorated, and it becomes easy for gate failure during injection molding to occur. The content of the aromatic vinyl compound in the component (a) If the amount is small, the vibration absorbability deteriorates and the cooling time at the time of injection molding becomes long.
In Comparative Examples 3 and 4, the amount of component (b) is out of the scope of the present invention. When there are few components (b), a softness | flexibility, transparency, the fluidity | liquidity at the time of injection molding will fall, and a product external appearance will deteriorate. When there are many components (b), the tackiness of a final product will become remarkable, the gate cut defect at the time of injection molding, and the cooling time at the time of shaping | molding become long.

Moreover, from the impact test, the molded body made of the thermoplastic elastomer composition of Examples 1 to 4 is a rubber-like elastic body of A hardness 30 silicone rubber, butyl rubber, and further compared to the molded body made of the composition of Comparative Example 3. Thus, the response acceleration with respect to the input acceleration is reduced, and the shock absorption is excellent.
Furthermore, from the vibration transmission test, the molded bodies made of the thermoplastic elastomer compositions of Examples 1 to 4 were able to keep the resonance frequency and the resonance magnification low in both the vertical direction and the horizontal direction, and had good vibration isolation characteristics.

  The molded body obtained from the thermoplastic elastomer composition having less oil bleed according to the present invention and having excellent transparency, compression set, vibration absorption, shock absorption, and injection molding processability is used for sound absorption and / or control. It can be used as a molded body for vibration, and is particularly applicable to a buffer member for a hard disk or a microphone holder member.

Claims (5)

(A) 100 parts by weight of a hydrogenated and / or partially hydrogenated block copolymer mixture having an aromatic vinyl compound content of 30 to 45% by weight (provided that (a) is (a-1) aromatic vinyl (A-2) Hydrogenation and / or aromatic vinyl compound content of less than 40% by weight with respect to 100 parts by weight of hydrogenated and / or partially hydrogenated block copolymer having a compound content of 50 to 70% by weight And (b) a thermoplastic elastomer composition containing 180 to 400 parts by weight of a softener for non-aromatic rubber. Molded body for sound absorption and / or damping.   (C) It consists of a thermoplastic elastomer composition which further contains 1 to 40 parts by weight of a petroleum resin.   (D) The molded article for sound absorption and / or vibration damping according to claim 1 or 2, comprising a thermoplastic elastomer composition further containing 1 to 60 parts by weight of a terpene oil.   The molded article according to any one of claims 1 to 3, wherein the molded article is used for shock buffering or vibration isolation in a hard disk drive or a disk-shaped recording medium reproducing apparatus.   The molded body according to any one of claims 1 to 3, wherein the molded body is for a microphone holder.