Thermoplastic elastomer composition

Abstract

To provide a thermoplastic elastomer composition having improved impact strength and an enlarged usable temperature range.SOLUTION: A thermoplastic elastomer composition contains a thermoplastic elastomer of 100 pts.mass and a wholly aromatic liquid crystal polymer of 0.1-40 pts.mass with a crystal melting temperature of 250°C or lower.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a thermoplastic elastomer composition containing a thermoplastic elastomer and a specific liquid crystal polymer, which has improved impact strength and an expanded usable temperature range. [Background technology]

[0002] Thermoplastic elastomers (hereinafter referred to as TPEs) are composed of soft segments such as rubber molecules or polyethers, and hard segments that prevent plastic deformation at room temperature, just like vulcanized rubber.When heated, they flow and can be molded in the same way as regular thermoplastics, and they exhibit rubber elasticity at room temperature.For this reason, TPEs are widely used in various industrial fields such as automobiles, construction, and medicine.

[0003] In order to improve the performance of thermoplastic elastomers, polymer blends, inorganic fillers, etc. have been incorporated. For example, Patent Document 1 proposes a composition comprising a thermoplastic elastomer and a thermotropic liquid crystalline polymer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2008 / 026509 Summary of the Invention [Problem to be solved by the invention]

[0005] However, the liquid crystal polymer to be blended with the TPE described in Patent Document 1 has a melting point of approximately 270°C, which causes thermal decomposition of the TPE during melt-kneading, resulting in a problem of reduced mechanical properties of the resulting resin composition.

[0006] The same document also describes an example of blending a liquid crystal polymer with a melting point of approximately 210°C with TPE, but because this liquid crystal polymer is a semi-aromatic liquid crystal polymer containing ethylenedioxy units as a constituent component, the mechanical properties of the resulting resin composition are not sufficiently improved, and no consideration has been given to improving the usable temperature range.

[0007] An object of the present invention is to provide a thermoplastic elastomer composition having improved impact strength and an expanded usable temperature range. [Means for solving the problem]

[0008] In view of the above problems, the present inventors have conducted extensive research and have found that by blending a specific amount of a liquid crystal polymer with a thermoplastic elastomer, a thermoplastic elastomer composition can be obtained which has improved impact strength and an expanded usable temperature range, and have thus completed the present invention.

[0009] That is, the present invention includes the following preferred embodiments. [1] A thermoplastic elastomer composition containing 100 parts by mass of a thermoplastic elastomer and 0.1 to 40 parts by mass of a wholly aromatic liquid crystal polymer having a crystalline melting temperature of 250°C or lower. [2] The wholly aromatic liquid crystal polymer is represented by the formulas (I) to (IV) [ka] [In the formula, Ar1 and Ar2 each represent one or more divalent aromatic groups, and p, q, r, and s each represent the composition ratio (mol %) of each repeating unit in the wholly aromatic liquid crystal polyester, and satisfy the following condition: 0.5≦p / q≦2.5 2 ≤ r ≤ 15, and 2≦s≦15] The thermoplastic elastomer composition according to [1], which is a wholly aromatic liquid crystal polyester containing a repeating unit represented by the following formula: [3] Formula (III) and / or Formula (IV) are represented by the formula (III) and / or Formula (IV), wherein Ar1 and Ar2 are each independently represented by the formula (1) to (4): [ka] The thermoplastic elastomer composition according to [2], comprising one or more repeating units which are aromatic groups selected from the group consisting of: [4] The thermoplastic elastomer composition according to any one of [1] to [3], wherein the thermoplastic elastomer is a polyester-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer, or a polyurethane-based thermoplastic elastomer. [5] A molded article made from the thermoplastic elastomer composition according to any one of [1] to [4]. [Effects of the Invention]

[0010] The thermoplastic elastomer composition of the present invention has improved impact strength and a wider usable temperature range. DETAILED DESCRIPTION OF THE INVENTION

[0011] The thermoplastic elastomer used in the thermoplastic elastomer composition of the present invention is an unmodified thermoplastic elastomer, such as a polyester thermoplastic elastomer, a polystyrene thermoplastic elastomer, a polyurethane thermoplastic elastomer, a polyolefin thermoplastic elastomer, or a polyamide thermoplastic elastomer. In the present invention, the unmodified thermoplastic elastomer is particularly a thermoplastic elastomer that is not acid-modified. Here, acid-modification refers to modification with, for example, an unsaturated carboxylic acid or a derivative thereof. Examples of unsaturated carboxylic acid or a derivative thereof include maleic acid, fumaric acid, itaconic acid, maleic anhydride, itaconic anhydride, maleic acid monomethyl ester, maleic acid monoethyl ester, maleic acid diethyl ester, and fumaric acid monomethyl ester.

[0012] Polyester-based thermoplastic elastomers are multi-block copolymers that contain polyester as hard segments in the molecule and polyether or polyester with a low glass transition temperature (Tg) as soft segments.

[0013] Examples of hard segments include polyesters composed of dicarboxylic acid components such as aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, and naphthalenedicarboxylic acid; alicyclic dicarboxylic acids such as 1,4-cyclohexanedicarboxylic acid; and aliphatic dicarboxylic acids such as succinic acid and adipic acid, and diol components such as aliphatic diols such as ethylene glycol, 1,2-propylene glycol, and 1,4-butanediol; and alicyclic diols such as cyclohexane-1,4-dimethanol.

[0014] The soft segment may be an aliphatic polyether such as polyethylene glycol, polypropylene glycol, or polybutylene glycol.

[0015] Thermoplastic polystyrene elastomers typically contain a styrene polymer block (Hb) as a hard segment and a conjugated diene polymer block or its hydrogenated block (Sb) as a soft segment. Examples of the structure of this thermoplastic styrene elastomer include a diblock structure represented by Hb-Sb, a triblock structure represented by Hb-Sb-Hb or Sb-Hb-Sb, a tetrablock structure represented by Hb-Sb-Hb-Sb, or a polyblock structure in which a total of five or more Hb and Sb units are linearly bonded.

[0016] Examples of styrene-based monomers used in the styrene-based polymer block (Hb) include styrene and its derivatives, such as styrene, α-methylstyrene, 2-methylstyrene, 4-methylstyrene, 4-propylstyrene, 4-t-butylstyrene, 4-cyclohexylstyrene, 4-dodecylstyrene, 2-ethyl-4-benzylstyrene, 4-(phenylbutyl)styrene, 2,4,6-trimethylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, and t-butoxystyrene; vinyl group-containing aromatic compounds such as vinyl naphthalenes, such as 1-vinylnaphthalene and 2-vinylnaphthalene; and vinylene group-containing aromatic compounds, such as indene and acenaphthylene. Among these, styrene is preferred. The styrene-based monomer may be used alone or in combination with two or more different monomers.

[0017] Examples of conjugated diene compounds used in the conjugated diene polymer block or its hydrogenated block (Sb) include butadiene, isoprene, 2,3-dimethylbutadiene, pentadiene, and hexadiene. Among these, butadiene is preferred. The conjugated diene compound may be one type or two or more types. Furthermore, other monomers such as ethylene, propylene, butylene, and styrene can also be copolymerized. The conjugated diene polymer block may be a partially or completely hydrogenated product.

[0018] Specific examples of polystyrene-based thermoplastic elastomers include styrene-isoprene diblock copolymers (SI), styrene-butadiene diblock copolymers (SB), styrene-isoprene-styrene triblock copolymers (SIS), styrene-butadiene / isoprene-styrene triblock copolymers (SB / IS), styrene-butadiene-styrene triblock copolymers (SBS), and hydrogenated products thereof. Among these, at least one selected from the group consisting of hydrogenated styrene-isoprene diblock copolymers (SEP), hydrogenated styrene-butadiene diblock copolymers (SEB), hydrogenated styrene-isoprene-styrene triblock copolymers (SEPS), hydrogenated styrene-butadiene / isoprene-styrene triblock copolymers (SEEPS), and hydrogenated styrene-butadiene-styrene triblock copolymers (SEBS) is preferred.

[0019] Thermoplastic polyurethane elastomers are linear multi-block copolymers that contain polyurethane as a hard segment obtained by the reaction of short-chain glycols with isocyanates and polyurethane as a soft segment obtained by the reaction of long-chain glycols with isocyanates. Polyurethane is a general term for compounds with a urethane bond (-NHCOO-) obtained by the polyaddition reaction (urethanization reaction) of isocyanates (-NCO) and alcohols (-OH).

[0020] Thermoplastic polyolefin elastomers include those containing polyolefin blocks such as polypropylene or polyethylene as hard segments and rubber blocks such as ethylene-propylene-diene copolymers as soft segments. Thermoplastic polyolefin elastomers are available in blend and implantable types.

[0021] Polyamide-based thermoplastic elastomers are multiblock copolymers that use polyamide as the hard segment and low-Tg polyether or polyester as the soft segment. The polyamide component that constitutes the hard segment is selected from nylon 6, 66, 610, 11, 12, etc., with nylon 6 and nylon 12 predominating. Long-chain polyols such as polyether diols and polyester diols are used as constituents of the soft segment. Specific examples of polyether polyols include diol poly(oxytetramethylene) glycol (PTMG) and poly(oxypropylene) glycol, and specific examples of polyester polyols include poly(ethylene adipate) glycol and poly(butylene-1,4-adipate) glycol.

[0022] The thermoplastic elastomer used in the present invention is preferably a polyester-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer or a polyurethane-based thermoplastic elastomer.

[0023] The thermoplastic elastomer composition of the present invention contains a predetermined amount of the below-described wholly aromatic liquid crystal polymer in addition to the above-described thermoplastic elastomer, thereby improving impact strength and widening the usable temperature range.

[0024] The wholly aromatic liquid crystal polymer used in the present invention is a wholly aromatic liquid crystal polyester or wholly aromatic liquid crystal polyester amide which forms an anisotropic molten phase and is called a thermotropic liquid crystal polymer by those skilled in the art.

[0025] The properties of the anisotropic melt phase of the wholly aromatic liquid crystal polymer can be confirmed by a conventional polarized light inspection method using cross polarizers, that is, by observing a sample placed on a hot stage under a nitrogen atmosphere.

[0026] Examples of repeating units constituting the wholly aromatic liquid crystal polymer used in the present invention include aromatic oxycarbonyl repeating units, aromatic dicarbonyl repeating units, aromatic dioxy repeating units, aromatic aminooxy repeating units, aromatic diamino repeating units, aromatic aminocarbonyl repeating units, and combinations thereof.

[0027] Specific examples of monomers that provide aromatic oxycarbonyl repeating units include aromatic hydroxycarboxylic acids such as 4-hydroxybenzoic acid, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 6-hydroxy-2-naphthoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, and the like, as well as alkyl, alkoxy, or halogen-substituted derivatives thereof, and ester-forming derivatives thereof such as acylation products, ester derivatives, and acid halides. Among these, 4-hydroxybenzoic acid and 6-hydroxy-2-naphthoic acid are preferred because they allow for easy adjustment of the mechanical properties, heat resistance, crystalline melting temperature, and moldability of the resulting wholly aromatic liquid crystal polymer to appropriate levels.

[0028] Specific examples of monomers that provide aromatic dicarbonyl repeating units include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-dicarboxybiphenyl, as well as their alkyl-, alkoxy-, or halogen-substituted derivatives, and their ester-forming derivatives such as ester derivatives and acid halides. Among these, terephthalic acid, isophthalic acid, and 2,6-naphthalenedicarboxylic acid are preferred because they allow the mechanical properties, heat resistance, crystalline melting temperature, and moldability of the resulting wholly aromatic liquid crystal polymer to be easily adjusted to appropriate levels.

[0029] Specific examples of monomers that provide aromatic dioxy repeating units include aromatic diols such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, 4,4'-dihydroxybiphenyl ether, and their alkyl, alkoxy, or halogen-substituted derivatives, as well as ester-forming derivatives such as acylated derivatives. Among these, hydroquinone and 4,4'-dihydroxybiphenyl are preferred because they are easy to adjust to appropriate levels the reactivity during polymerization and the mechanical properties, heat resistance, crystalline melting temperature, and moldability of the resulting wholly aromatic liquid crystal polymer.

[0030] Monomers that provide aromatic aminooxy repeating units, aromatic diamino repeating units and aromatic aminocarbonyl repeating units include aromatic hydroxyamines, aromatic diamines and aromatic aminocarboxylic acids.

[0031] The wholly aromatic liquid crystal polymer used in the present invention may contain an aromatic oxydicarbonyl repeating unit or a thioester bond, provided that the object of the present invention is not impaired. Examples of monomers that provide a thioester bond include mercaptoaromatic carboxylic acids, aromatic dithiols, and hydroxyaromatic thiols. The amount of these monomers used is preferably 10 mol% or less based on the total amount of the aromatic oxycarbonyl repeating unit, aromatic dicarbonyl repeating unit, aromatic dioxy repeating unit, aromatic aminooxy repeating unit, aromatic diamino repeating unit, and aromatic aminocarbonyl repeating unit.

[0032] Among copolymers combining these repeating units, some may form an anisotropic molten phase and some may not, depending on the monomer structure, composition ratio, and sequence distribution of each repeating unit in the copolymer. However, the wholly aromatic liquid crystal polymer used in the present invention is limited to copolymers that form an anisotropic molten phase.

[0033] The wholly aromatic liquid crystal polymer used in the present invention may be a blend of two or more kinds of wholly aromatic liquid crystal polymers.

[0034] The crystalline melting temperature of the wholly aromatic liquid crystal polymer used in the present invention, measured by a differential scanning calorimeter, is 250° C. or lower, preferably 245° C. or lower, more preferably 235° C. or lower, even more preferably 225° C. or lower, still more preferably less than 210° C., particularly preferably 200° C. or lower, and most preferably 195° C. or lower. The wholly aromatic liquid crystal polymer in the present invention, has a crystalline melting temperature, measured by a differential scanning calorimeter, of preferably 150° C. or higher, more preferably 155° C. or higher, and even more preferably 160° C. or higher.

[0035] In this specification and claims, the term "crystalline melting temperature" refers to the crystalline melting peak temperature measured using a differential scanning calorimeter (hereinafter abbreviated as DSC) at a heating rate of 20 ° C. / min. More specifically, a sample of a wholly aromatic liquid crystal polymer is measured at a heating rate of 20 ° C. / min from room temperature to the endothermic peak temperature (Tm1), and then held at a temperature 20 to 50 ° C. higher than Tm1 for 10 minutes. The sample is then cooled to room temperature or -100 ° C. at a cooling rate of 20 ° C. / min. After that, the endothermic peak is measured again at a heating rate of 20 ° C. / min. The temperature at the peak top is taken as the crystalline melting temperature of the wholly aromatic liquid crystal polymer. For example, a DSC7020 manufactured by Hitachi High-Tech Science Corporation can be used as a measuring instrument.

[0036] As the wholly aromatic liquid crystal polymer used in the present invention, wholly aromatic liquid crystal polyesters are preferably used, and wholly aromatic liquid crystal polyesters containing repeating units represented by formulae (I) to (IV) are more preferably used. [ka]

[0037] [In the formula, Ar1 and Ar2 each represent one or more divalent aromatic groups, and p, q, r, and s each represent the composition ratio (mol %) of each repeating unit in the wholly aromatic liquid crystal polyester, and satisfy the following condition: 0.5≦p / q≦2.5 2 ≤ r ≤ 15, and 2≦s≦15.]

[0038] For the above-mentioned wholly aromatic liquid crystal polyesters that are preferably used, the composition ratio p (mol %) according to the above formula (I) and the composition ratio q (mol %) according to the formula (II) preferably satisfy the relationship p>q, and p / q is more preferably 1.01 to 2.0, even more preferably 1.03 to 1.9, and particularly preferably 1.08 to 1.8.

[0039] In the above-mentioned wholly aromatic liquid crystal polyesters that are preferably used, the total composition ratio of p and q is preferably 70 to 96 mol %, more preferably 76 to 90 mol %.

[0040] In the fully aromatic liquid crystal polyesters preferably used above, the composition ratio p in formula (I) is preferably 35 to 55 mol %, more preferably 38 to 53 mol %, and the composition ratio q in formula (II) is preferably 25 to 45 mol %, more preferably 28 to 43 mol %.

[0041] The wholly aromatic liquid crystal polyester preferably used in the present invention contains repeating units represented by formula (I) and formula (II) at least in the above molar ratio (p / q), and optionally in the above total composition ratio of p and q and / or individual composition ratios of p and q (mol %), and thereby exhibits a crystalline melting temperature of 250°C or less.

[0042] In the wholly aromatic liquid crystal polyester preferably used in the present invention, the composition ratio r according to formula (III) and the composition ratio s according to formula (IV) are each preferably 2 to 15 mol %, more preferably 4 to 14 mol %, and r and s are preferably equimolar amounts.

[0043] In the above repeating unit, for example, when Ar1 (or Ar2) represents two or more divalent aromatic groups, it means that the wholly aromatic liquid crystal polyester contains two or more repeating units represented by formula (III) (or (IV)) according to the type of divalent aromatic group. In this case, the composition ratio r according to formula (III) (or the composition ratio s according to formula (IV)) represents the total composition ratio of the two or more repeating units.

[0044] Examples of monomers that provide the repeating unit represented by formula (I) include 4-hydroxybenzoic acid and its ester-forming derivatives such as acylates, ester derivatives and acid halides.

[0045] Examples of monomers that provide the repeating unit represented by formula (II) include 6-hydroxy-2-naphthoic acid and its ester-forming derivatives such as acylates, ester derivatives and acid halides.

[0046] Examples of monomers that provide the repeating unit represented by formula (III) include aromatic diols such as hydroquinone, resorcinol, 2,6-dihydroxynaphthalene, 2,7-dihydroxynaphthalene, 1,6-dihydroxynaphthalene, 1,4-dihydroxynaphthalene, 4,4'-dihydroxybiphenyl, 3,3'-dihydroxybiphenyl, 3,4'-dihydroxybiphenyl, and 4,4'-dihydroxybiphenyl ether, as well as ester-forming derivatives such as acylated products thereof.

[0047] Examples of monomers that provide the repeating unit represented by formula (IV) include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, 2,6-naphthalenedicarboxylic acid, 1,6-naphthalenedicarboxylic acid, 2,7-naphthalenedicarboxylic acid, 1,4-naphthalenedicarboxylic acid, and 4,4'-dicarboxybiphenyl, as well as ester-forming derivatives thereof, such as ester derivatives and acid halides.

[0048] Furthermore, among the wholly aromatic liquid crystal polyesters that are preferably used in the present invention, wholly aromatic liquid crystal polyesters in which Ar1 and Ar2 in the repeating units represented by formula (III) and formula (IV) each independently contain one or more aromatic groups selected from the group consisting of aromatic groups represented by formulas (1) to (4) are more preferably used. [ka]

[0049] Among these, as the repeating unit represented by formula (III), aromatic groups represented by formula (1) and formula (3), that is, the use of hydroquinone, 4,4'-dihydroxybiphenyl, and their ester-forming derivatives as monomers that give these repeating units, are particularly preferred, since they allow for easy adjustment of the reactivity during polymerization and the mechanical properties, heat resistance, crystalline melting temperature, and molding processability of the resulting wholly aromatic liquid crystal polyester to appropriate levels.

[0050] Furthermore, as the repeating unit represented by formula (IV), it is particularly preferred to use aromatic groups represented by formulas (1), (2) and (4), i.e., terephthalic acid, isophthalic acid and 2,6-naphthalenedicarboxylic acid and their ester-forming derivatives as monomers that give these repeating units, because this makes it easy to adjust the mechanical properties, heat resistance, crystalline melting temperature and molding processability of the resulting wholly aromatic liquid crystal polyester to appropriate levels.

[0051] In the above repeating units, for example, when Ar1 (or Ar2) contains two or more aromatic groups, it means that the wholly aromatic liquid crystal polyester contains two or more repeating units represented by formula (III) (or (IV)) according to the type of divalent aromatic group. In this case, the composition ratio r according to formula (III) (or the composition ratio s according to formula (IV)) represents the total composition ratio of the two or more repeating units.

[0052] In the wholly aromatic liquid crystal polyester preferably used in the present invention, the total composition ratio of the repeating units [p+q+r+s] is preferably 100 mol %, but other repeating units may be further contained within a range that does not impair the object of the present invention.

[0053] Examples of monomers that provide other repeating units constituting the wholly aromatic liquid crystal polyester preferably used in the present invention include other aromatic hydroxycarboxylic acids, aromatic hydroxyamines, aromatic diamines, aromatic aminocarboxylic acids, aromatic hydroxydicarboxylic acids, aromatic mercaptocarboxylic acids, aromatic dithiols, aromatic mercaptophenols, and combinations thereof.

[0054] Other aromatic hydroxycarboxylic acids include, for example, 3-hydroxybenzoic acid, 2-hydroxybenzoic acid, 5-hydroxy-2-naphthoic acid, 3-hydroxy-2-naphthoic acid, 4'-hydroxyphenyl-4-benzoic acid, 3'-hydroxyphenyl-4-benzoic acid, 4'-hydroxyphenyl-3-benzoic acid, and ester-forming derivatives thereof, such as acylated products, ester derivatives, and acid halides.

[0055] The total composition ratio of the repeating units provided by these other monomer components is preferably 10 mol % or less based on the total repeating units.

[0056] The method for producing the wholly aromatic liquid crystal polymer used in the present invention will be described below.

[0057] There are no particular limitations on the method for producing the wholly aromatic liquid crystal polymer used in the present invention, and known polycondensation methods for forming ester bonds, amide bonds, etc. from the combination of the above-mentioned monomers, such as melt acidolysis and slurry polymerization, can be used.

[0058] The melt acidolysis method is a preferred method for producing the wholly aromatic liquid crystalline polymer used in the present invention, in which the monomers are first heated to form a melt of reactants, and then the reaction is continued to obtain a molten polymer. A vacuum may be applied to facilitate removal of volatile by-products (e.g., acetic acid, water, etc.) produced in the final stage of condensation.

[0059] Slurry polymerization is a process in which the reaction is carried out in the presence of a heat exchange fluid, and the solid product is obtained in a state suspended in the heat exchange medium.

[0060] In both the melt acidolysis method and the slurry polymerization method, the polymerizable monomer components used in producing the wholly aromatic liquid crystal polymer can be subjected to the reaction at room temperature in a modified form in which the hydroxyl group and / or amino group is acylated, i.e., as a lower acylated product. The lower acyl group preferably has 2 to 5 carbon atoms, more preferably 2 or 3 carbon atoms. Particularly preferred is a method in which an acetylated product of the monomer is used in the reaction.

[0061] The acylated monomer may be one that has been separately acylated and synthesized in advance, or may be produced in the reaction system by adding an acylating agent such as acetic anhydride to the monomer during the production of the wholly aromatic liquid crystal polymer.

[0062] In either the molten acidolysis method or the slurry polymerization method, a catalyst may be used during the reaction, if necessary.

[0063] Specific examples of catalysts include organic tin compounds such as dialkyltin oxides (e.g., dibutyltin oxide) and diaryltin oxides; metal oxides such as titanium dioxide; antimony compounds such as antimony trioxide; organic titanium compounds such as alkoxytitanium silicates and titanium alkoxides; alkali and alkaline earth metal salts of carboxylic acids (e.g., potassium acetate, sodium acetate); and gaseous acid catalysts such as Lewis acids (e.g., boron trifluoride) and hydrogen halides (e.g., hydrogen chloride).

[0064] The catalyst is used in an amount of usually 1 to 1000 ppm, preferably 2 to 100 ppm, based on the total amount of monomers.

[0065] The wholly aromatic liquid crystal polymer obtained by the polycondensation reaction in this manner is withdrawn in a molten state from the polymerization reaction vessel and then processed into pellets, flakes, or powder.

[0066] In the thermoplastic elastomer composition of the present invention, the proportion of the wholly aromatic liquid crystal polymer is 0.1 to 40 parts by mass relative to 100 parts by mass of the thermoplastic elastomer, and from the viewpoints of impact strength and usable temperature range, it is preferably 0.5 to 28 parts by mass, more preferably 1 to 27 parts by mass, even more preferably 2 to 26 parts by mass, and particularly preferably 3 to 25 parts by mass.

[0067] If the content of the wholly aromatic liquid crystal polymer is less than 0.1 parts by mass, the effects of improving the impact strength of the thermoplastic elastomer composition and expanding the usable temperature range cannot be sufficiently obtained, and if it exceeds 40 parts by mass, the properties of the thermoplastic elastomer composition, such as Izod impact strength, tend to deteriorate.

[0068] The thermoplastic elastomer composition of the present invention is characterized in that the crystalline melting temperature of the wholly aromatic liquid crystalline polymer used is 250°C or lower, so that the wholly aromatic liquid crystalline polymer is uniformly dispersed in the thermoplastic elastomer matrix resin and can be blended by melt kneading at low temperatures. As a result, thermal decomposition of the thermoplastic elastomer is suppressed, impact strength is improved, and the usable temperature range is expanded, resulting in a resin composition.

[0069] Therefore, a compatibilizer is not particularly necessary when blending, but a compatibilizer may be added to further improve the compatibility between the thermoplastic elastomer and the wholly aromatic liquid crystal polymer. When a compatibilizer is added, the amount added is preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of the thermoplastic elastomer.

[0070] The thermoplastic elastomer composition of the present invention may contain inorganic and / or organic fillers as optional components. However, depending on the type and content of the fillers, the flexibility of the composition may be impaired. Therefore, it is preferable that the composition does not contain inorganic and / or organic fillers.

[0071] Specific examples of inorganic and / or organic fillers that may be contained in the thermoplastic elastomer composition of the present invention include glass fibers, silica alumina fibers, alumina fibers, carbon fibers, potassium titanate fibers, aluminum borate fibers, aramid fibers, polyarylate fibers, polybenzimidazole fibers, talc, mica, graphite, wollastonite, dolomite, clay, glass flakes, glass beads, glass balloons, calcium carbonate, barium sulfate, titanium oxide, etc. These may be used alone or in combination of two or more.

[0072] Among these, talc is preferred because it has an excellent balance between physical properties and cost.

[0073] The inorganic and / or organic filler may be surface-treated. Examples of the surface treatment method include a method in which a surface treatment agent is adsorbed onto the surface of the filler, and a method in which a surface treatment agent is added during kneading.

[0074] Examples of surface treatment agents include reactive coupling agents such as silane coupling agents, titanate coupling agents, and borane coupling agents, and lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid metal salts, and fluorocarbon surfactants.

[0075] In addition to the thermoplastic elastomer and wholly aromatic liquid crystal polymer, other additives and resin components may be added to the thermoplastic elastomer composition of the present invention, as long as the object of the present invention is not impaired.

[0076] Specific examples of other additives include lubricants such as higher fatty acids, higher fatty acid esters, higher fatty acid amides, and higher fatty acid metal salts (here, higher fatty acids refer to those having 10 to 25 carbon atoms), release agents such as polysiloxanes and fluororesins, colorants such as dyes, pigments, and carbon black, flame retardants, antistatic agents, surfactants, nucleating agents such as talc, organic phosphates, and sorbitols, antiblocking agents, antioxidants such as phosphorus-based antioxidants, phenol-based antioxidants, and sulfur-based antioxidants, weathering agents, heat stabilizers, and neutralizing agents. These additives can be used alone or in combination of two or more.

[0077] When the thermoplastic elastomer composition contains other additives, the content thereof is preferably 0.01 to 5 parts by mass, more preferably 0.1 to 3 parts by mass, as the total amount of the other additives, per 100 parts by mass of the total amount of the thermoplastic elastomer and the wholly aromatic liquid crystal polymer.

[0078] If the total amount of other additives is less than 0.01 parts by mass, it will be difficult for the additives to function properly when they are contained, and if it exceeds 5 parts by mass, the thermal stability of the thermoplastic elastomer composition during molding processing will tend to deteriorate.

[0079] Furthermore, when additives such as a lubricant, a mold release agent, or an antiblocking agent are used among the other additives, they may be added when the thermoplastic elastomer composition is produced, or may be attached to the surface of pellets of the thermoplastic elastomer composition during molding.

[0080] Specific examples of other resin components include thermoplastic resins such as polyamide, polyester, polyacetal, polyphenylene ether and modified products thereof, polysulfone, polyethersulfone, polyetherimide, polyamideimide, etc., and thermosetting resins such as phenol resin, epoxy resin, polyimide resin, etc. These resin components may be used alone or in combination of two or more.

[0081] When other resin components are contained, the content thereof is preferably 100 parts by mass or less, and more preferably 80 parts by mass or less, per 100 parts by mass of the total amount of the thermoplastic elastomer and the wholly aromatic liquid crystal polymer.

[0082] The thermoplastic elastomer composition of the present invention can be obtained by blending the above-mentioned thermoplastic elastomer, wholly aromatic liquid crystal polymer, and optionally the above-mentioned inorganic filler and / or organic filler, other additives, other resin components, etc. in a predetermined composition, and melt-kneading the mixture using a Banbury mixer, kneader, single-screw or twin-screw extruder, etc. Alternatively, the thermoplastic elastomer composition of the present invention can also be obtained by dry-blending the thermoplastic elastomer and wholly aromatic liquid crystal polymer, and melt-kneading the mixture in a molding machine.

[0083] The thermoplastic elastomer composition of the present invention thus obtained has an Izod impact strength at 23°C according to ASTM D256 of usually 90 J / m or more, preferably 100 to 500 J / m, and more preferably 110 to 480 J / m.

[0084] The thermoplastic elastomer composition of the present invention has a difference ΔT (Tg2-Tg1) between the glass transition temperature (Tg1) and the glass transition temperature (Tg2) of the single thermoplastic elastomer, of usually 1.5° C. or more, preferably 2 to 25° C., and more preferably 2.1 to 20° C. Since the thermoplastic elastomer composition of the present invention has a low glass transition temperature and a wide usable temperature range, it can be suitably used in low-temperature environments such as cold regions.

[0085] In this specification and claims, the term "glass transition temperature" refers to the midpoint of the step-like change in the DSC curve measured with a differential scanning calorimeter at a heating rate of 20°C / min. More specifically, a sample of a thermoplastic elastomer composition is measured at a heating rate of 20°C / min from room temperature, and after observing the endothermic peak temperature (Tm1), the sample is held at a temperature 20 to 50°C higher than Tm1 for 10 minutes, then cooled to -100°C at a cooling rate of 20°C / min, and measured again at a heating rate of 20°C / min. The midpoint of the step-like change in the DSC curve is taken as the glass transition temperature of the thermoplastic elastomer composition. Examples of measuring instruments that can be used include a DSC7020 manufactured by Hitachi High-Tech Science Corporation.

[0086] The thermoplastic elastomer composition of the present invention can be processed into molded articles such as injection molded articles, films, sheets and nonwoven fabrics by conventional molding methods such as injection molding, compression molding, extrusion molding and blow molding.

[0087] The present invention will be described in detail below with reference to examples, but the present invention is not limited to these examples. [Example]

[0088] The crystalline melting temperature, glass transition temperature and Izod impact strength in the examples were measured by the methods described below.

[0089] <Measurement of crystalline melting temperature and glass transition temperature> Measurements were performed using a differential scanning calorimeter (DSC7020, manufactured by Hitachi High-Tech Science Corporation). Resin samples of the examples and comparative examples were measured under conditions of a temperature increase from room temperature of 20°C / min, and after observing the endothermic peak temperature (Tm1), they were held at a temperature 20 to 50°C higher than Tm1 for 10 minutes. The samples were then cooled to -100°C under conditions of a temperature decrease of 20°C / min, and then measured again under conditions of a temperature increase of 20°C / min, and the endothermic peak was observed. The temperature showing the peak top was taken as the crystalline melting temperature of the resin sample, and the midpoint of the step-like change in the DSC curve was taken as the glass transition temperature of the resin sample.

[0090] <Izod impact strength> Using an injection molding machine (MINIMAT M26 / 15 manufactured by Sumitomo Heavy Industries, Ltd.), strip-shaped test specimens measuring 65 mm in length, 12.7 mm in width, and 2.0 mm in thickness were molded at a cylinder temperature of 20 to 40°C above the melting point and a mold temperature of 80°C, and measurements were made in accordance with ASTM D256.

[0091] In the examples and comparative examples, the following abbreviations represent the following compounds. TPE: Thermoplastic elastomer LCP: fully aromatic liquid crystal polymer POB: 4-hydroxybenzoic acid BON6: 6-hydroxy-2-naphthoic acid BP: 4,4'-dihydroxybiphenyl HQ: Hydroquinone NDA: 2,6-naphthalenedicarboxylic acid IPA: Isophthalic acid TPA: Terephthalic acid

[0092] (thermoplastic elastomer) The following thermoplastic elastomers were used: Thermoplastic polystyrene elastomer (TPS): Septon 8007L, manufactured by Kuraray Co., Ltd. Thermoplastic polyester elastomer (TPEE): Hytrel 4057N, manufactured by DuPont-Toray Co., Ltd. Thermoplastic polyurethane elastomer 1 (TPU-1): HF-1098A, manufactured by Fuwafon TPU Co., Ltd. Thermoplastic polyurethane elastomer 2 (TPU-2): HF-SRH8175A, manufactured by Fuwafon TPU Co., Ltd.

[0093] (Synthesis of fully aromatic liquid crystal polymers) [Synthesis example 1 (LCP-1)] A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with 386.0 g (43 mol%) of POB, 403.6 g (33 mol%) of BON6, 145.2 g (12 mol%) of BP, 126.0 g (9 mol%) of NDA, and 32.4 g (3 mol%) of IPA, and further charged with 1.03 times the molar amount of acetic anhydride relative to the hydroxyl group amount (mol) of all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0094] The temperature was raised from room temperature to 150°C in a nitrogen gas atmosphere over 1 hour and maintained at that temperature for 30 minutes. The temperature was then rapidly raised to 210°C while distilling off the by-product acetic acid and maintained at that temperature for 30 minutes. The temperature was then raised to 340°C over 4 hours, after which the pressure was reduced to 10 mmHg over 80 minutes. The polymerization reaction was terminated when the specified torque was reached, and the contents were removed from the reactor and crushed to obtain LCP pellets. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The crystalline melting temperature (Tm) of the obtained LCP pellets measured by DSC was 183°C.

[0095] [Synthesis example 2 (LCP-2)] A reaction vessel equipped with a stirrer with a torque meter and a distillation tube was charged with 323.2 g (36 mol%) of POB, 48.9 g (4 mol%) of BON6, 323.9 g (30 mol%) of TPA, 169.4 g (14 mol%) of BP, and 114.5 g (16 mol%) of HQ, and further charged with 1.03 times the moles of acetic anhydride relative to the amount (moles) of hydroxyl groups in all monomers, and deacetic acid polymerization was carried out under the following conditions.

[0096] The temperature was raised from room temperature to 145°C over 1 hour under a nitrogen gas atmosphere and maintained at 145°C for 30 minutes. The temperature was then raised to 350°C over 7 hours while distilling off the by-product acetic acid, and the pressure was then reduced to 5 mmHg over 80 minutes. The polymerization reaction was terminated when a predetermined torque was reached, and the contents were removed from the reactor and crushed to obtain pellets of a wholly aromatic liquid crystal polymer. The amount of acetic acid distilled during polymerization was nearly the theoretical value. The crystalline melting temperature (Tm) of the resulting LCP pellets was 335°C.

[0097] [Examples 1 to 5 and Comparative Examples 1 to 6] The thermoplastic elastomer and LCP-1 were blended in the amounts shown in Table 1, and melt-kneaded using a twin-screw extruder (PCM-30, manufactured by Ikegai Corporation) at a cylinder temperature of LCP crystalline melting temperature +10 to +60°C to obtain pellets of the thermoplastic elastomer composition (Examples 1 to 5 and Comparative Examples 1 to 5). The Izod impact strength and glass transition temperature of the obtained pellets were measured using the methods described above. The results are shown in Table 1.

[0098] On the other hand, in Comparative Example 6, in which LCP-2 was used, the crystalline melting temperature of LCP-2 was high, and the thermoplastic elastomer was thermally deteriorated during melt-kneading, generating decomposition gas, and the discharge of the extruded strand was unstable, so pellets of the thermoplastic elastomer composition could not be obtained.

[0099] As shown in Table 1, the thermoplastic elastomer compositions of Examples 1 to 5 all had an Izod impact strength of 120 to 371 J / m and a glass transition temperature of -27.5 to -66.5°C, and had improved Izod impact strength and a wider usable temperature range compared to those of Comparative Examples 1 and 3 to 5 that did not contain a wholly aromatic liquid crystal polymer.

[0100] On the other hand, the thermoplastic elastomer composition of Comparative Example 2 was inferior to the thermoplastic elastomer compositions of Examples 1 to 5 in Izod impact strength.

[0101] [Table 1]

Claims

1. A thermoplastic elastomer composition comprising 100 parts by mass of a thermoplastic elastomer and 0.1 to 40 parts by mass of a wholly aromatic liquid crystal polymer having a crystalline melting temperature of 250°C or lower, The wholly aromatic liquid crystal polymer is represented by the formulas (I) to (IV): 【Chemistry 1】 [In the formula, Ar 1 and Ar 2 each represent one or more divalent aromatic groups, and p, q, r, and s each represent the composition ratio (mol %) of each repeating unit in the wholly aromatic liquid crystal polyester, and satisfy the following condition: 0.5≦p / q≦2.5 2≦r≦15, and 2≦s≦15] A wholly aromatic liquid crystal polyester containing a repeating unit represented by The thermoplastic elastomer is a polyester-based thermoplastic elastomer, a polystyrene-based thermoplastic elastomer, or a polyurethane-based thermoplastic elastomer. Thermoplastic elastomer composition.

2. Formula (III) and / or Formula (IV) are Ar １ and Ar ２ are independently expressed by the formulas (1) to (4) 【Chemistry 2】 2. The thermoplastic elastomer composition according to claim 1, comprising one or more repeating units which are aromatic groups selected from the group consisting of:

3. A molded article made from the thermoplastic elastomer composition according to claim 1 or 2.

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