JP2006083323A - Thermoplastic elastomer composition for use in injection molding - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition for use in injection molding which is excellent in the mechanical strengths and thermal fusion strength without detriment to physical properties such as flexibility and moldability and which gives a large die swell ratio at the time of injecting and a little bleeding of a softener. <P>SOLUTION: The thermoplastic elastomer composition for use in injection molding contains (a) 100 parts by weight of at least one block copolymer selected from the group consisting of a block copolymer comprising at least one of the polymer block A having mainly an aromatic vinyl compound and at least one of the polymer block B having mainly a conjugated diene compound; its hydrogenated block copolymer; and a hydrogenated product of a conjugated diene compound block copolymer and contains (b) 5-1,000 parts by weight of a propylene-based block copolymer consisting of 70-10% by weight of a crystalline propylene-based polymer part and 30-90% by weight of an amorphous propylene/α-olefin copolymer part, with having a die swell ratio of 1.2 times or more. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic elastomer composition for injection molding, and particularly relates to a styrenic thermoplastic elastomer composition excellent in injection moldability.

  In recent years, thermoplastic elastomers, which are soft materials with rubber elasticity and do not require a vulcanization process, can be molded and processed like thermoplastic resins, and can be recycled. Automotive elastomers, home appliance parts, wire coatings, medical use Widely used in the fields of parts, footwear, sundries, etc.

  Among thermoplastic elastomers, polystyrene-based thermoplastic elastomers such as styrene-butadiene block copolymer (SBS) and styrene-isoprene block copolymer (SIS), which are block copolymers of aromatic vinyl compound-conjugated diene compound, are The thermoplastic elastomer composition which is rich in flexibility, has a good rubber elasticity at room temperature, and is excellent in processability, is widely used as a substitute for vulcanized rubber. In addition, an elastomer composition obtained by hydrogenating an intramolecular double bond of a block copolymer of styrene and a conjugated diene in these elastomers is further improved as an elastomer having improved heat aging resistance (thermal stability) and weather resistance. Widely used.

  Such a styrenic thermoplastic elastomer composition is usually used by adding a softening agent such as polypropylene resin or paraffin oil for imparting mechanical strength, heat resistance, etc. and adjusting the hardness.

  For example, a softener obtained by blending a hydrogenated styrene thermoplastic elastomer with a non-aromatic rubber softener, a copolymer of propylene and one or more of 1-olefins other than propylene, and an inorganic filler. In addition, it is rich in flexibility and is excellent in heat distortion resistance and mechanical strength, and is a relatively inexpensive elastomeric composition (see, for example, Patent Document 1), a hydrogenated styrenic thermoplastic elastomer, A molding resin composition that is flexible and is excellent in strength, heat resistance and transparency, blended with isotactic polypropylene having a melting point of 150 ° C. or higher or a copolymer mainly composed thereof (for example, see Patent Document 2). Polyethylene or ethylene-based copolymer polymerized with a styrene thermoplastic elastomer with a single site catalyst and polypropylene or propylene A thermoplastic elastomer composition that is rich in flexibility, excellent in heat distortion resistance, mechanical strength and molding processability, and contains a small amount of n-heptane extract (for example, see Patent Document 3). ), Styrenic thermoplastic elastomer, non-aromatic rubber softener, polyethylene or ethylene-based copolymer polymerized with a single site catalyst, polypropylene or propylene-based copolymer, inorganic filler A thermoplastic elastomer composition having excellent heat distortion resistance, oil resistance, flexibility, mechanical strength and molding processability (for example, see Patent Document 4), hydrogenated styrene thermoplastic elastomer, polypropylene or propylene Made of a polypropylene-ethylene-propylene copolymer having a melting point of 135 ° C or higher Resin composition with excellent heat resistance, oil resistance, and molding processability (for example, see Patent Document 5), hydrogenated styrene thermoplastic elastomer, hydrocarbon rubber softener, crystalline propylene A block copolymer comprising a polymer part and an amorphous propylene-α-olefin copolymer part, comprising a ethylene-α-olefin copolymer having a maximum melting peak temperature of 135 ° C. or less by DSC, flexibility, mechanical A thermoplastic elastomer composition (see, for example, Patent Document 6) excellent in strength, heat fusion strength, and moldability is disclosed.

  In addition, it contains a resin component and two or more rubber components, at least one rubber component forms a continuous phase and / or a network-like phase, and at least one other rubber component forms an isolated phase. In an excellent thermoplastic elastomer composition, a combination of an olefin resin or a styrene resin as a resin component, a combination of a styrene thermoplastic elastomer and a reactor TPO which is an olefin thermoplastic elastomer as two or more types of rubber components (for example, , See Patent Document 7.) In a polyolefin resin sheet for printing made of a blend of a polyolefin resin and a styrene resin, examples of the polyolefin resin in the blend include a polyethylene resin and a polypropylene resin. Hydrogenated styrene thermoplastic as resin Elastomer, and the like, polypropylene and ethylene as propylene resin - exemplary reactor polymerization resins such as propylene rubber (EPR rubber) is (for example, see Patent Document 8).

However, when injection molding is performed using a composition in which a polypropylene resin is blended with these styrene thermoplastic elastomers, there is a problem that the die swell ratio does not increase and the injection moldability is poor. In other words, because the die swell phenomenon in which the melted material ejected from the nozzle part during injection molding is ejected as a purged material having a diameter larger than the nozzle diameter due to the ballast effect is small, jetting, welds, transfer defects, etc. occur. There is a problem that it is easy to do. Further, a composition in which a propylene copolymer is blended with a styrene thermoplastic elastomer, and further a low melting point ethylene resin, for example, an ethylene-α-olefin copolymer having a maximum melting peak temperature by DSC of 135 ° C. or less is blended. In the case of a product, there is a problem that heat resistance is lowered and molding workability is lowered at the same time.
JP 58-206644 A JP 58-215446 A Japanese Patent Laid-Open No. 10-158465 JP 2000-17141 A JP 2000-239481 A JP 2001-220513 A JP 2002-285004 A JP 2001-2702304 A

  The object of the present invention is to improve the problems of the styrenic thermoplastic elastomer composition blended with the polyolefin obtained by the above-mentioned conventional technology, without impairing the physical properties such as excellent flexibility and moldability, and mechanical strength. Another object of the present invention is to provide a thermoplastic elastomer composition for injection molding which is excellent in heat-sealing strength, has a large die swell ratio at the time of injection, and has a small softener bleed.

  As a result of repeating various studies in order to solve the above problems, the present inventor formulated a specific block copolymer, a non-aromatic rubber softener, and a specific propylene block copolymer. Was found to be excellent in flexibility, mechanical strength, weather resistance, moldability, less softener bleed, and excellent die swell ratio, and completed the present invention. is there.

That is, according to the first invention of the present invention, (a) (a-1) at least one polymer block A mainly composed of an aromatic vinyl compound and a polymer block B mainly composed of a conjugated diene compound. A block copolymer comprising at least one of (a-2), a hydrogenated block copolymer obtained by hydrogenating (a-1), and (a-3) a conjugated diene compound block copolymer. 100 parts by weight of at least one block copolymer selected from the group consisting of a hydrogenated product, and (b) a crystalline propylene-based polymer part, and an amorphous propylene / α-olefin copolymer part, And 5 to 1000 parts by weight of a propylene-based block copolymer obtained by a multistage polymerization method in which the proportion of the amorphous propylene / α-olefin copolymer part in the entire copolymer is 30 to 90% by weight Shi And,
The die swell ratio obtained from the outer diameter of the obtained string-like material is 1.2 times or more by injection molding from the nozzle at a shear rate γ = 2400 sec ⁻¹ obtained by the following formula (1) or (2). A thermoplastic elastomer composition for injection molding is provided.
In the case of a rectangular flow path: γ = 2 (n + 2) Q / WH ² (1)
In the case of a circular pipe: When γ = (n + 3) Q / πr ³ (2)
(In Formula (1) and Formula (2),
γ: shear rate (sec ⁻¹ )
Q: Flow rate (mm ³ / sec)
W: Channel width (mm)
H: Channel height (mm)
n: Numerical value obtained by plotting the relationship between viscosity and shear rate on a graph and calculating from the slope of the graph (1 / n-1) r: Channel radius (mm)
It is. )

  Further, according to the second invention of the present invention, in the first invention, the flexural modulus specified by JIS K6758 (bending speed: 2.7 mm / min, 1/4 inch bending test piece) of component (b). Is a thermoplastic elastomer composition for injection molding, characterized in that is 500 MPa or less.

  According to a third aspect of the present invention, in the first or second aspect, the peak top melting point on the highest temperature side of the DSC melting curve of the component (b) is 135 ° C. or higher. A thermoplastic elastomer composition for molding is provided.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the component (a) is a styrene-ethylene / propylene-styrene block copolymer (SEPS), styrene-ethylene / ethylene / Injection characterized by being one of propylene-styrene block copolymer (SEEPS), styrene-ethylene butene-styrene block copolymer (SEBS), or styrene-butadiene-styrene block copolymer (SBS) A thermoplastic elastomer composition for molding is provided.

  According to a fifth aspect of the present invention, there is provided a thermoplastic elastomer composition for injection molding, wherein the hardness (HDA) is 5 to 95 in any one of the first to fourth aspects. Is done.

  According to the sixth invention of the present invention, there is provided a molded article comprising the thermoplastic elastomer composition for injection molding according to any one of the first to fifth inventions.

  The thermoplastic elastomer composition for injection molding of the present invention is excellent in mechanical strength and heat fusion strength without impairing physical properties such as excellent flexibility and moldability, and has a large die swell ratio at the time of injection, and It is a composition with less bleeding of the softening agent.

  The components, production method and the like of the thermoplastic elastomer composition for injection molding of the present invention will be described in detail below.

1. Component (a) Block Copolymer of Thermoplastic Elastomer Composition for Injection Molding (a) The block copolymer used in the thermoplastic elastomer composition for injection molding of the present invention is the following (a-1), (a -2) and at least one block copolymer selected from the group consisting of (a-3).

(A-1) 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 Block copolymer Component (a-1) is 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. For example, an aromatic vinyl compound-conjugated diene compound block copolymer having a structure such as A-B, A-B-A, B-A-B-A, or A-B-A-B-A may be mentioned. it can.

The polymer block A mainly composed of an aromatic vinyl compound is preferably composed of only an aromatic vinyl compound, or an aromatic vinyl compound of 50% by weight or more, preferably 70% by weight or more, and an optional component such as a conjugated diene compound. And a copolymer block.
The polymer block B mainly composed of a conjugated diene compound is preferably composed of only a conjugated diene compound or an optional component such as a conjugated diene compound of 50% by weight or more, preferably 70% by weight or more and an aromatic vinyl compound. The copolymer block.
In addition, the said block copolymer contains an aromatic vinyl compound 5-60 weight%, for example, Preferably it is 20-50 weight%.

  Further, in the polymer block A mainly composed of these aromatic vinyl compounds and the polymer block B mainly composed of conjugated diene compounds, the distribution of units derived from the conjugated diene compound or aromatic vinyl compound in the molecular chain is random, It may be tapered (in which the monomer component increases or decreases along the molecular chain), partially in a block form, or any combination thereof. When there are two or more polymer blocks A mainly composed of aromatic vinyl compounds or polymer blocks B mainly composed of conjugated diene compounds, each polymer block has a different structure even if each has the same structure. There may be.

  As the aromatic vinyl compound constituting the block copolymer, for example, one or more kinds can be selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene, etc. preferable. 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.

  Specific examples of the block copolymer include styrene-butadiene-styrene copolymer (SBS), styrene-isoprene-styrene copolymer (SIS), and styrene-isoprene / butadiene-styrene copolymer (SIBS). Can be mentioned.

  Many methods for producing these block copolymers have been proposed. As typical methods, for example, a lithium catalyst or a Ziegler-type catalyst is prepared by the method described in Japanese Patent Publication No. 40-23798. It can be obtained by block polymerization in an inert medium.

(A-2) Hydrogenated block copolymer The hydrogenated block copolymer component (a-2) is a hydrogenated product of (a-1), and is a polymer block A mainly composed of an aromatic vinyl compound. It is a hydrogenated product of a block copolymer comprising at least one 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 in the hydrogenated block copolymer, the microstructure is arbitrary. For example, when the block B is composed of butadiene alone, in the polybutadiene block, The 1,2-microstructure is preferably 20-50% by weight, particularly preferably 25-45% by weight.
The hydrogenation rate is arbitrary, but is preferably 50% or more, more preferably 55% or more, and still more preferably 60% or more. Alternatively, the 1,2-bond may be selectively hydrogenated.
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 the block B is composed of isoprene alone, in the polyisoprene block, preferably 70 to 100% by weight of the isoprene has a 1,4-microstructure and is preferably an aliphatic double bond derived from isoprene. Those which are at least 90% hydrogenated are preferred.

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

  The number average molecular weight of the block copolymer is preferably in the range of 5,000 to 1,500,000, more preferably 10,000 to 550,000, and still more preferably 90,000 to 400,000. Distribution is 10 or less. The molecular structure of the block copolymer may be linear, branched, radial, or any combination thereof.

  Specific examples of the hydrogenated block polymer component (a-2) include styrene-ethylene / butene / styrene copolymer (SEBS), styrene / ethylene / propylene / styrene copolymer (SEPS), and styrene / ethylene / ethylene.・ Propylene-styrene copolymer (SEEPS), Styrene-butadiene-butylene-styrene copolymer (partially hydrogenated styrene-butadiene-styrene copolymer, SBBS), Styrene-ethylene-butene-crystalline ethylene block copolymer (SEBC) and the like.

(A-3) Hydrogenated product of conjugated diene compound block copolymer The hydrogenated product of the conjugated diene compound block copolymer used in the present invention (a-3) is a hydrogenated product of a conjugated diene compound block copolymer. Examples thereof include a block copolymer (CEBC) having a crystalline ethylene block and an amorphous ethylene-butene block obtained by hydrogenation of a block copolymer of butadiene. In the present invention, the hydrogenated product of the conjugated diene compound block copolymer may be used alone or in combination of two or more.
Specific examples of the hydrogenated product of the conjugated diene compound block copolymer include Dynalon 6100P (trademark; manufactured by JSR Corporation) and the like.

(B) Propylene-based block copolymer The propylene-based block copolymer component (b) used in the thermoplastic elastomer composition for injection molding of the present invention comprises a crystalline propylene-based polymer portion, an amorphous propylene / α- It is a block copolymer composed of an olefin copolymer part. Examples of the crystalline propylene polymer portion include a propylene homopolymer or a random copolymer of propylene and a small amount of other α-olefin. On the other hand, examples of the amorphous propylene / α-olefin copolymer include non-crystalline random copolymers of propylene and other α-olefins.

  The other α-olefins are preferably those having 2 or 4 to 12 carbon atoms, and specific examples include ethylene, 1-butene, 3-methyl-1-butene, 3-methyl-1-pentene, Examples include 4-methyl-1-pentene, 4,4-dimethyl-1-pentene, vinylcyclopentane, vinylcyclohexane and the like. These α-olefins may be used alone or in combination of two or more.

  In addition to this α-olefin, 1,4-hexadiene, 5-methyl-1,5-hexadiene, 1,4-octadiene, cyclohexadiene, cyclooctadiene, dicyclopentadiene, 5-methylene-2-norbornene, A ternary or quaternary copolymer obtained by copolymerizing a non-conjugated diene such as 5-ethylidene-2-norbornene, 5-butylidene-2-norbornene, and 5-isopropenyl-2-norbornene can also be used.

The proportion of the amorphous propylene / α-olefin copolymer part in the propylene-based block copolymer is 30 to 90% by weight, preferably 40 to 80% by weight. If the proportion of the amorphous propylene / α-olefin copolymer part is less than 30% by weight, the flexibility of the product is inferior and the die swell ratio is also deteriorated. On the other hand, when it exceeds 90% by weight, compression set is deteriorated.
Here, the proportion of the non-crystalline propylene / α-olefin copolymer part is as follows. 1 g of propylene block copolymer is placed in 300 ml of xylene in an oil bath and dissolved under stirring at 140 ° C. which is the boiling point of xylene. Then, after 1 hour, the temperature was lowered to 100 ° C. within 1 hour while continuing the stirring, transferred to a quenching oil bath, rapidly cooled to 23 ± 2 ° C. with stirring, and the polymer was precipitated, and allowed to stand for 20 minutes or more. The resulting precipitate is naturally filtered with a filter paper, and the filtrate is evaporated to dryness using an evaporator, further dried under reduced pressure at 120 ° C. for 2 hours, and then allowed to cool to room temperature and measured for its weight. .

Furthermore, the propylene content of the amorphous propylene / α-olefin copolymer part is preferably 5 to 90% by weight, more preferably 10 to 85% by weight.
Here, the propylene content of the non-crystalline propylene / α-olefin copolymer part is a xylene-soluble polymer obtained when the proportion of the non-crystalline propylene / α-olefin copolymer part is measured. Is a value obtained by infrared spectroscopy.

  Furthermore, the melt flow rate (MFR) measured based on JIS K7210 (230 degreeC, load 2160g) of a propylene-type block copolymer becomes like this. Preferably it is 0.2-800 dg / min. If the MFR is less than 0.2 dg / min, the molding processability of the thermoplastic elastomer composition tends to be inferior, and if it is 800 dg / min or more, the strength is lowered.

  Moreover, the bending elastic modulus prescribed | regulated by JISK6758 (bending speed: 2.7 mm, 1/4 inch bending test piece) of a propylene-type block copolymer has preferable 500 Mpa or less, More preferably, it is 30-300 Mpa. When the flexural modulus exceeds 500 MPa, the die swell ratio does not increase, so that improvement in formability is not recognized.

Further, the peak top melting point on the highest temperature side of the melting curve measured using a DSC (differential scanning calorimeter) of the propylene-based block copolymer is preferably 135 ° C. or more, more preferably 140 to 170 ° C. . If the peak top melting point on the highest temperature side of the DSC melting curve is less than 135 ° C., the resulting thermoplastic elastomer composition tends to be sticky and the heat resistance tends to be inferior. On the other hand, when the temperature exceeds 170 ° C., the heat-fusibility of the thermoplastic elastomer composition deteriorates.
Here, the peak top melting point of DSC is 5 minutes after cooling the sample to 250 ° C. using a differential scanning calorimeter (DSC) and then cooling it to −30 ° C. at a cooling rate of 20 ° C./min. This is a value obtained as a temperature indicating the main endothermic peak of the endothermic peak curve obtained when the temperature is raised to 250 ° C. at a rate of temperature rise of 20 ° C./min.

The production method of the propylene-based block copolymer used in the present invention is not particularly limited. For example, an organoaluminum compound such as triethylaluminum, a titanium atom, a magnesium atom, a halogen atom, and t-butyl-methyl-diethoxy. Propylene in the first stage polymerization or other α-olefin of about 2 to 12 carbon atoms in the first stage polymerization using a catalyst composed of a solid component essentially containing an electron donating compound such as an organic silicon compound such as silane In the presence of the catalyst, a propylene homopolymer or a crystalline propylene polymer block comprising a propylene / α-olefin copolymer is produced. In the presence of the catalyst, propylene / α-olefin is supplied with another α-olefin having about 2 to 12 carbon atoms. It made by preparing a non-crystalline propylene · alpha-olefin copolymer block made of a copolymer.
As described above, the propylene block copolymer used in the present invention is a copolymer in which a crystalline propylene polymer block and an amorphous propylene / α-olefin copolymer block are produced in a multi-stage process. Crystalline propylene / α-olefin copolymer part, for example, ethylene / propylene copolymer rubber part, ethylene / butene-1 copolymer rubber part is finely dispersed in the copolymer, and as a result, elastomer composition It is thought that effects such as the die swell ratio of the product are expressed.

  The polymerization may be carried out by any of batch, continuous, and semi-batch methods. The first stage polymerization is carried out in the gas phase or in the solution, preferably in the gas phase, and the second stage and subsequent polymerizations. Is preferably carried out in the gas phase.

  The propylene block copolymer used in the present invention is Catalloy (manufactured by Basell), P.I. E. It can be obtained as a commercial product under the trademarks R (manufactured by Tokuyama) and Newcon (manufactured by Chisso)

  The compounding quantity of the component (b) in the thermoplastic elastomer composition for injection molding of this invention is 5-1000 weight part with respect to 100 weight part of component (a), Preferably it is 10-500 weight part. If the blending amount exceeds 1000 parts by weight, the moldability of the thermoplastic elastomer composition is deteriorated and the rubber elasticity is further lowered. On the other hand, if it is less than 5 parts by weight, the fluidity of the thermoplastic elastomer composition is impaired and the die swell ratio is not improved.

(C) Softener for non-aromatic rubber In the thermoplastic elastomer composition for injection molding of the present invention, (c) a softener for non-aromatic rubber can be used as necessary. The component (c) functions to control the flexibility of the thermoplastic elastomer composition and adjust the hardness without impairing the supple texture. Examples of component (c) include non-aromatic mineral oils or liquid or low molecular weight synthetic softeners. The mineral oil softener used for rubber is a mixture of the aromatic ring, naphthene ring, and paraffin chain, and the paraffin chain carbon number accounts for 50% or more of the total carbon number. A naphthene ring having 30 to 40% carbon atoms is distinguished by being called a naphthene type, and those having 30% or more aromatic carbon number being called aromatic.

  The mineral oil rubber softeners used as the non-aromatic rubber softeners of the present invention are classified into paraffinic and naphthenic ones. Aromatic softeners are not preferred because their use makes thermoplastic resins soluble, inhibits the crosslinking reaction, and cannot improve the physical properties of the resulting composition. As the non-aromatic rubber softener of the present invention, paraffin-based ones are preferable, and paraffin-based ones having less aromatic ring components are particularly suitable. Examples of the liquid or low molecular weight synthetic softener include polybutene, hydrogenated polybutene, and low molecular weight polyisobutylene.

These non-aromatic rubber softeners have a dynamic viscosity at 37.8 ° C. of 20 to 50,000 cSt, preferably 20 to 1,000 cSt, and a dynamic viscosity at 100 ° C. of 5 to 1,500 cSt. Preferably, it is 5 to 100 cSt, the pour point is -10 to -25 ° C, and the flash point (COC) is 170 to 350 ° C. Furthermore, a thing with a weight average molecular weight of 100-2,000 is preferable.
Among these, aliphatic paraffin oils such as PW-90 and PW-380 manufactured by Idemitsu Kosan Co., Ltd. can be mentioned as non-aromatic rubber softeners that are generally available.

  The compounding quantity of the component (c) in the thermoplastic elastomer composition for injection molding of this invention is 0-300 weight part with respect to 100 weight part of component (a), Preferably it is 5-200 weight part. If the blending amount exceeds 300 parts by weight, there is a concern about bleeding.

(D) Other components In the thermoplastic elastomer composition for injection molding of the present invention, various antioxidants such as phosphorus-based, phenol-based, sulfur-based, anti-aging agent, light, etc., as long as the object of the present invention is not impaired. Various weathering agents such as stabilizers, UV absorbers, copper damage prevention agents, modified silicone oils, silicone oils, waxes, acid amides, fatty acids, fatty acid metal salts, various lubricants, aromatic phosphate metal salts, gelols, etc. Various nucleating agents, various plasticizers such as glycerin fatty acid ester, aromatic paraffin oil, phthalic acid, ester, various fillers such as magnesium oxide, zinc oxide, magnesium hydroxide, calcium carbonate, talc, various Additives such as colorants can be used. In order to prevent troubles such as bleeding out on the surface of the molded product, those having high compatibility with the thermoplastic elastomer composition of the present invention are preferable.

2. Production of Thermoplastic Elastomer Composition for Injection Molding The thermoplastic elastomer composition for injection molding of the present invention uses the above components (a) and (b) and, if necessary, (c) and (d). It can be produced by melting and kneading at the same time or 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 melt kneading is preferably 150 to 240 ° C.

3. Physical Properties and Use of Thermoplastic Elastomer Composition for Injection Molding The thermoplastic elastomer composition for injection molding of the present invention is 210 at a shear rate γ = 2400 sec ⁻¹ determined from the nozzle according to the following formula (1) or (2). The die swell ratio obtained from the outer diameter of the string-like material obtained by injection molding in the range of ˜230 ° C. is 1.2 times or more, preferably 1.4 times or more.
In the case of a rectangular flow path: γ = 2 (n + 2) Q / WH ² (1)
In the case of a circular pipe: When γ = (n + 3) Q / πr ³ (2)
(In Formula (1) and Formula (2),
γ: shear rate (sec ⁻¹ )
Q: Flow rate (mm ³ / sec)
W: Channel width (mm)
H: Channel height (mm)
n: Numerical value obtained by plotting the relationship between viscosity and shear rate on a graph and calculating from the slope of the graph (1 / n-1) r: Channel radius (mm)
It is. )
By setting the die swell ratio to 1.2 times or more, problems such as jetting, welds, and transfer defects during injection can be solved.

  Moreover, the hardness (HDA) of the thermoplastic elastomer composition for injection molding of the present invention is 5 to 95, preferably 20 to 90. If the HDA is less than 5, the oil bleeds, and if it exceeds 95, the product becomes inflexible.

  The thermoplastic elastomer composition for injection molding of the present invention can be processed into various molded products by conventionally known injection molding (insert molding method, two-color molding method, sandwich molding method, gas injection molding method, etc.). In particular, in the injection molding method, since the die swell ratio at the time of injection can be increased, various physical properties of the injection molded body can be improved.

  Molded products thus obtained include automotive interior and exterior parts (doors, instrument panels, etc.), household electrical appliance parts (packing, hoses, OA equipment panels, edge materials, etc.), building materials parts (window frame frames, outer wall materials, etc.) , Shutters, rain gutters, etc.), civil engineering, agricultural materials (hollow plate materials, corrugated plate materials, honeycomb materials, joiners, nets, corrugated pipes, etc.), food packaging materials, medical equipment parts, furniture parts, daily goods, etc. Can do.

  The present invention will be specifically described by the following examples and comparative examples, but the present invention is not limited to these examples. In addition, the measuring method and sample of the physical property used by this invention are shown below.

1. Physical property measurement method and manufacturability evaluation method (1) Specific gravity: Measured according to JIS K 7112.
(2) Hardness: In accordance with JIS K 7215, a 6.3 mm thick press sheet was used as the test piece.
(3) Tensile strength, 100% modulus, elongation: In accordance with JIS K 6723, a 1 mm thick press sheet was punched into a No. 2 dumbbell-type test piece and used. The tensile speed was 200 mm / min (room temperature).
(4) Compression set: In accordance with JIS K6262, a 6.3 mm thick press sheet was used as a test piece. The measurement was performed at 70 ° C. × 22 hours. In addition, 75% or less, preferably 50% or less is judged as good.
(5) MFR: Measured according to JIS K 7210 (230 ° C., 2160 g load).
(6) Die swell ratio: obtained by injecting a thermoplastic elastomer composition at a shear rate of 2400 sec ⁻¹ from a circular nozzle diameter of 3 mmφ using an injection molding machine IS-80EPN (clamping pressure 80 t) manufactured by Toshiba Machine The outer diameter of the string was measured with a caliper. The resin temperature at the time of molding was adjusted at 210 to 230 ° C.
(7) Moldability: A 130 × 130 × 2 mm injection-molded product was molded under the same conditions as in (7), the appearance was visually observed, and judged according to the following criteria.
○: Good shapeability without sinks and burrs ×: Conspicuous jetting and welds (8) Bleedability: The sheet formed in (8) is placed in a gear oven at 70 ° C. for 168 hours, and thereafter The stickiness on the sheet surface was observed and judged according to the following criteria.
○: The molded product surface does not feel sticky. ×: Sticky and dirty.

2. Sample (a1) Hydrogenated block copolymer (SEEPS) used in Examples and Comparative Examples: Septon 4077 (manufactured by Kuraray Co., Ltd.), styrene content 30% by weight, number average molecular weight 260,000, weight average molecular weight 320, 000, molecular weight distribution 1.23, hydrogenation rate 90% or more (a2) hydrogenated block copolymer (SEBS): Kraton G1657 (manufactured by Kraton Polymer Co., Ltd.) styrene content 15%, weight average molecular weight 10,000
(A3) Block copolymer (SBS): Sorprene T-411 (Asahi Kasei) hardness 75A, styrene content 30%
(A4) Hydrogenated block copolymer (CEBC): Dynalon 6101B (manufactured by JSR) hardness 68A, styrene content 0%
(B1) Propylene-based block copolymer (R-TPO): Q-100F (manufactured by Basell) Crystalline propylene / ethylene copolymer part: 40% by weight, amorphous propylene / ethylene copolymer content: 60 % By weight, flexural modulus (JIS K 6758; bending speed: 2.7 mm / min, using 1/4 inch bending specimen): 80 MPa, peak top melting point on the highest temperature side of the DSC melting curve: 142 ° C., MFR: 0 .6 dg / min (b2: comparative component) propylene-based block copolymer (BCPP): BC-8 (manufactured by Nippon Polychem Co., Ltd.) Crystalline propylene polymer part: 85% by weight, amorphous propylene / ethylene copolymer Content: 15 wt%, flexural modulus (JIS K 6758; bending speed 2.7 mm / min, using 1/4 inch bending test piece): 1000 MPa, DSC melting Peak top melting point on the highest temperature side of the solution curve: 162 ° C., MFR: 1.8 g / 10 minutes (b3: comparative component) ethylene / α-olefin copolymer having a melting point of 95 ° C. or less: Engage 8100 (DuPont Dow Elastomer Co., Ltd.) Manufactured) Peak top on the highest temperature side of the DSC melting curve: melting point 60 ° C., density 0.87 g / cm ³ , MFR: 2.0 dg / min (190 ° C., 2160 g load)
(C) Non-aromatic rubber softener (Oil): Diana process oil PW-90 (manufactured by Idemitsu Kosan Co., Ltd.) Dynamic viscosity (40 ° C.): 95.54 cSt, Dynamic viscosity (100 ° C.): 11. 25 cSt, COC: 270 ° C.
(D) Talc: JA13R (manufactured by Asada Powder Co., Ltd.) particle size of 3 μm or less

(Examples 1-7, Comparative Examples 1-4)
Using each component in the amounts shown in Tables 1 and 2, the mixture was put into a twin screw extruder having an L / D of 47, and melt kneaded at a kneading temperature of 180 ° C. and a screw rotation speed of 350 rpm to be pelletized. 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.

As is clear from Tables 1 and 2, Examples 1 to 7 are thermoplastic elastomer compositions for injection molding according to the present invention, and are excellent in die swell ratio, moldability, and bleed resistance.
On the other hand, the thermoplastic elastomer composition in which the propylene-based block copolymer component (b) obtained by the multistage polymerization method exceeded the upper limit was inferior in moldability (Comparative Example 1), and was obtained by the multistage polymerization method. The thermoplastic elastomer composition in which the propylene-based block copolymer component (b) is less than the lower limit has a small swell ratio and poor moldability (Comparative Example 2), and the propylene-based block copolymer obtained by the multistage polymerization method In addition to the coalescence (b), the thermoplastic elastomer composition using the ethylene / α-olefin copolymer having a maximum melting peak temperature of 135 ° C. or less by a differential scanning calorimeter (DSC) is inferior in moldability and bleed ( Comparative Example 3), a thermoplastic elastomer composition using a propylene-based block copolymer component (b) having too little amorphous propylene / α-olefin copolymer portion, The ratio and the compression set are inferior (Comparative Example 4).

  The thermoplastic elastomer composition for injection molding of the present invention is excellent in mechanical strength and heat fusion strength without impairing physical properties such as excellent flexibility and moldability, and has a large die swell ratio at the time of injection, and Since it is a softener softening bleed composition, various injection-molded products, especially automobile interior and exterior parts, home appliance parts, building material parts, civil engineering, agricultural materials, food packaging materials, medical equipment parts, furniture parts, daily goods Etc. can be used.

Claims (6)

(A) (a-1) 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; a-2) at least one selected from the group consisting of a hydrogenated block copolymer obtained by hydrogenating (a-1) and a hydrogenated product of (a-3) conjugated diene compound block copolymer 100 parts by weight of a block copolymer, and (b) a crystalline propylene polymer part and an amorphous propylene / α-olefin copolymer part, and the amorphous propylene / containing 5 to 1000 parts by weight of a propylene-based block copolymer obtained by a multistage polymerization method in which the proportion of the α-olefin copolymer part is 30 to 90% by weight, and
The die swell ratio obtained from the outer diameter of the obtained string-like material is 1.2 times or more by injection molding from the nozzle at a shear rate γ = 2400 sec ⁻¹ obtained by the following formula (1) or (2). A thermoplastic elastomer composition for injection molding.
In the case of a rectangular flow path: γ = 2 (n + 2) Q / WH ² (1)
In the case of a circular pipe: When γ = (n + 3) Q / πr ³ (2)
(In Formula (1) and Formula (2),
γ: shear rate (sec ⁻¹ )
Q: Flow rate (mm ³ / sec)
W: Channel width (mm)
H: Channel height (mm)
n: Numerical value obtained by plotting the relationship between viscosity and shear rate on a graph and calculating from the slope of the graph (1 / n-1) r: Channel radius (mm)
It is. )   2. The injection molding according to claim 1, wherein the flexural modulus specified by JIS K 6758 (bending speed: 2.7 mm / min, 1/4 inch bending test piece) of component (b) is 500 MPa or less. Thermoplastic elastomer composition.   The thermoplastic elastomer composition for injection molding according to claim 1 or 2, wherein the peak top melting point on the highest temperature side of the DSC melting curve of component (b) is 135 ° C or higher.   Component (a) is a styrene-ethylene / propylene / styrene block copolymer (SEPS), a styrene / ethylene / ethylene / propylene / styrene block copolymer (SEEPS), or a styrene / ethylene / butene / styrene block copolymer (SEBS). ) Or a styrene-butadiene-styrene block copolymer (SBS), The thermoplastic elastomer composition for injection molding according to any one of claims 1 to 3.   Hardness (HDA) is 5-95, The thermoplastic elastomer composition for injection molding of any one of Claims 1-4 characterized by the above-mentioned.   A molded article comprising the thermoplastic elastomer composition for injection molding according to any one of claims 1 to 5.