JP2005281373A - Thermoplastic elastomer composition - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition excellent in molding processability, flexibility and rubber properties, and also excellent in strain restorability after subjected to strain at high temperatures over a long period, and to provide a molded product of the same. <P>SOLUTION: The thermoplastic elastomer composition comprises (i) a crosslinked olefin rubber(I) and an addition-polymerized block copolymer(II) composed of aromatic vinyl compound polymer blocks(A) and (hydrogenated) conjugated diene compound polymer blocks(B), wherein the polymer blocks(A) have alkylstyrene units each with a 1-8C alkyl group bound to the benzene ring, and crosslinked with at least the polymer blocks(A) in the mass ratio(I)/(II) of (90:10) to (10:90) and (ii) 10-300 pts. mass of a polyolefin(III) based on a total of 100 pts. mass of the components(I) and (II) and ≤300 pts. mass of a rubber flexibilizer(IV). A method for producing this composition is also provided. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a thermoplastic elastomer composition containing a cross-linked olefin rubber, a specific cross-linked addition polymerization block copolymer, a polyolefin and optionally a softener for rubber, a method for producing the same, and the thermoplastic elastomer composition The present invention relates to a molded article made of a product. The thermoplastic elastomer composition and molded article of the present invention are excellent in moldability and flexibility, have no bleeding out of the rubber softener, and excellent in strain recovery after being strained at high temperature for a long period of time. It can be used effectively for a wide range of applications.

  In recent years, thermoplastic elastomer materials that are rubber-elastic soft materials that do not require a vulcanization process and that can be molded and recycled in the same way as thermoplastic resins are used in automotive parts, home appliance parts, electric wire coatings, and medical use. Widely used in the fields of parts, miscellaneous goods, footwear, etc. Among such thermoplastic elastomer materials, an olefinic thermoplastic elastomer composition comprising a cross-linked olefinic rubber and a polyolefin is excellent in strain recovery after applying strain at high temperature. Widely used (see Patent Document 1). However, when this elastomer composition and a molded product comprising the elastomer composition are subjected to strain at a high temperature for a long time, the strain recovery is insufficient, and the rubber softener blended in the elastomer composition bleeds out on the surface of the molded product. As a result, the appearance of the molded product is poor, and the surface feels poor due to stickiness.

  Further, a thermoplastic elastomer composition is known in which a hydrogenated product of a block copolymer composed of an aromatic vinyl compound polymer block and a conjugated diene compound polymer block is blended with an olefin rubber (see Patent Document 2). . Further, a thermoplastic resin having a gel content of 97% or more containing a hydrogenated product and a softening agent of a block copolymer comprising a crystalline polyolefin resin, an olefin rubber, a styrene polymer block and a butadiene and / or isoprene polymer block. Elastomer compositions are known (see Patent Document 3). In these thermoplastic elastomer compositions, the hydrogenated block copolymer composed of the styrene polymer block and the conjugated diene compound polymer block, which are the constituent components, is excellent in the retention of the rubber softener, so that it can be removed from the surface of the molded product. Although there are few problems such as bleed-out of the softener, the strain recovery after applying strain at high temperature is insufficient, and when strain is applied over a long period of time at high temperature, the strain is not fully recovered.

Japanese Examined Patent Publication No. 58-46138 JP-A-7-286078 JP-A-8-291239

The purpose of the present invention is excellent in molding processability and flexibility, no bleed out of the softener, and there is little residual strain even after applying strain at high temperature for a long period of time, and strain recovery after applying strain at high temperature It is to provide a thermoplastic elastomer composition having excellent properties and a molded product comprising the same.
And the objective of this invention is providing the manufacturing method of the thermoplastic elastomer composition which has the above-mentioned outstanding characteristic.

  The present inventors have intensively studied to achieve the above object. As a result, an olefinic thermoplastic elastomer composition containing a crosslinked olefinic rubber and polyolefin, and optionally further containing a rubber softener, a polymer block comprising a structural unit derived from an aromatic vinyl compound, and a conjugated diene compound A block copolymer having an optionally hydrogenated polymer block composed of a structural unit derived from the polymer block composed of a structural unit derived from an aromatic vinyl compound and having an alkyl group having 1 to 8 carbon atoms When a block copolymer having a structural unit derived from an alkylstyrene having a substituted benzene ring and crosslinked at least with a polymer block portion composed of a structural unit derived from an aromatic vinyl compound is included, a molding process is performed. Excellent flexibility and flexibility, no softener bleed-out and long at high temperatures Thermoplastic elastomer compositions that provide residual little moldings distortion and excellent recovery of the strain, even after the addition of strain is found that the resulting over.

  The inventors of the present invention have described that the above-mentioned thermoplastic elastomer composition is hydrogenated with a polymer block composed of a structural unit derived from an olefinic rubber, an aromatic vinyl compound, and a structural unit derived from a conjugated diene compound. An alkylstyrene having a benzene ring substituted with an alkyl group having 1 to 8 carbon atoms on a polymer block comprising a structural unit derived from an aromatic vinyl compound, the block copolymer having an optional polymer block Smooth production by adding a crosslinking agent to a mixture containing a block copolymer having a derived structural unit, polyolefin and, optionally, a rubber softener in a specific ratio, and dynamically crosslinking under melting conditions The present invention was completed based on these findings.

That is, the present invention
(1) (i) At least one polymer block (A) comprising a crosslinked olefin rubber (I) and a structural unit derived from an aromatic vinyl compound (hereinafter sometimes referred to as “aromatic vinyl compound unit”). And a block copolymer having at least one polymer block (B) composed of a structural unit derived from a conjugated diene compound which may be hydrogenated (hereinafter sometimes referred to as “conjugated diene compound unit”). The combined block (A) has a structural unit derived from alkylstyrene in which at least one alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring (hereinafter sometimes referred to as “C1-8 alkylstyrene unit”); At least the addition polymerization block copolymer (II) crosslinked with the polymer block (A) is converted into a crosslinked olefin rubber (I): addition polymerization block. Click copolymer (II) = 90: 10~10: contains a weight ratio of 90; and,
(Ii) For a total of 100 parts by mass of the cross-linked olefin rubber (I) and the addition polymerization block copolymer (II);
10 to 300 parts by weight of polyolefin (III); and
300 parts by mass or less of rubber softener (IV);
It is contained in the ratio of
And this invention,
(2) The thermoplastic elastomer composition according to (1), wherein the structural unit derived from alkylstyrene in the polymer block (A) of the addition polymerization block copolymer (II) is a structural unit derived from p-methylstyrene. Includes things.

Furthermore, the present invention provides
(3) From a structural unit derived from an olefinic rubber (I ₀ ) and at least one polymer block (A) composed of a structural unit derived from an aromatic vinyl compound and a conjugated diene compound optionally hydrogenated A block copolymer having at least one polymer block (B) and having a structure derived from alkylstyrene in which at least one alkyl group having 1 to 8 carbon atoms is bonded to the benzene ring in the polymer block (A) Containing an addition polymerization block copolymer (II ₀ ) having a unit in a mass ratio of olefin rubber (I ₀ ): addition polymerization block copolymer (II ₀ ) = 90: 10 to 10:90, And a total of 100 parts by mass of the olefin rubber (I ₀ ) and the addition polymerization block copolymer (II ₀ );
10 to 300 parts by mass of polyolefin (III);
300 parts by weight or less of rubber softener (IV); and
0.1 to 20 parts by mass of the crosslinking agent (V);
(1) The method for producing a thermoplastic elastomer composition according to (1) above, wherein the mixture containing the ratio is dynamically crosslinked under melting conditions.
And this invention,
(4) A molded article comprising the thermoplastic elastomer composition (1) or (2).

  The thermoplastic elastomer composition of the present invention is excellent in molding processability and flexibility, has no bleeding out of a rubber softener, has an excellent appearance and feel of a molded product, and is distorted even after being strained at a high temperature for a long time. Is very excellent in strain recovery after applying strain at high temperature (hereinafter sometimes referred to as “strain recovery at high temperature”). Therefore, the thermoplastic elastomer composition and the molded product of the present invention make use of the above-mentioned excellent characteristics, such as various industrial vehicles such as automobiles, construction machinery vehicles, agricultural machinery vehicles, railway vehicles, machine tools, construction machinery, agricultural machinery, It can be suitably used in a wide range of applications such as mining machines, industrial robots, chemicals, pharmaceutical plants, chemical transfer machines, food industry machines, hydraulic tools, and various other engineering and mining machines, ships, medical fields, and miscellaneous goods.

The present invention is described in detail below.
The crosslinked olefin rubber (I) constituting the thermoplastic elastomer composition of the present invention is a crosslinked product of an olefin rubber (hereinafter, the olefin rubber before crosslinking may be referred to as “olefin rubber (I ₀ )”). is there. The crosslinked olefin rubber (I) is a copolymer rubber of ethylene and one or more α-olefins having 3 to 20 carbon atoms (hereinafter, this may be referred to as “ethylene / α-olefin copolymer rubber”). Or a copolymer rubber of ethylene and one or more of α-olefin having 3 to 20 carbon atoms and one or more of non-conjugated polyene (hereinafter referred to as “ethylene / α-olefin / A non-conjugated polyene copolymer rubber) or a cross-linked ethylene / α-olefin copolymer rubber and an ethylene / α-olefin / non-conjugated polyene copolymer rubber. A cross-linked product may be used in combination.
Among them, the crosslinked olefin rubber (I) constituting the thermoplastic elastomer composition of the present invention is more preferably a cross-linked product of ethylene / α-olefin / non-conjugated polyene, which has better strain recovery at high temperatures. This is preferable.

  Examples of the α-olefin having 3 to 20 carbon atoms forming the ethylene / α-olefin copolymer rubber and the ethylene / α-olefin / non-conjugated polyene copolymer rubber include propylene, 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-decene and the like, and ethylene / α-olefin copolymer rubber and ethylene / α-olefin / non-conjugated polyene copolymer rubber are those α- It can be formed using one or more olefins. Among these, the C3-C20 α-olefins forming the ethylene / α-olefin copolymer rubber and the ethylene / α-olefin / nonconjugated polyene copolymer rubber are propylene, 1-butene, 1-hexene and Preferred is / or 1-octene, and more preferred is propylene and / or 1-butene.

  In the ethylene / α-olefin copolymer rubber, the molar ratio of ethylene: α-olefin having 3 to 20 carbon atoms maintains the balance between the mechanical properties of the thermoplastic elastomer composition and the strain recovery at high temperatures. 40:60 to 93: 7, preferably 50:50 to 85:15, and more preferably 60:40 to 80:20.

  Examples of the non-conjugated polyene forming the ethylene / α-olefin / non-conjugated polyene copolymer rubber include 5-ethylidene-2-norbornene, dicyclopentadiene, 5-propylidene-2-norbornene, and 5-vinyl- Cyclic polyenes such as 2-norbornene, 2,5-norbornadiene, 1,4-cyclohexadiene, 1,4-cyclooctadiene, 1,5-cyclooctadiene, 1,4-hexadiene, 4-methyl-1,4 -Hexadiene, 5-methyl-1,4-hexadiene, 5-methyl-1,5-heptadiene, 6-methyl-1,5-heptadiene, 6-methyl-1,6-octadiene, 7-methyl-1,6 -Octadiene, 5,7-dimethyl-1,6-octadiene, 7-methyl-1,7-nonadiene, 8-methyl-1,7 Nonadiene, 8-methyl-1,8-decadiene, 9-methyl-1,8-decadiene, 4-ethylidene-1,6-octadiene, 7-methyl-4-ethylidene-1,6-octadiene, 7-methyl- 4-ethylidene-1,6-nonadiene, 7-ethyl-4-ethylidene-1,6-nonadiene, 6,7-dimethyl-4-ethylidene-1,6-octadiene, 6,7-dimethyl-4-ethylidene- A chain polyene having an internal unsaturated bond having 6 to 15 carbon atoms, such as 1,6-nonadiene, 1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene, 1,8-nonadiene, 1, List α, ω-dienes such as 9-decadiene, 1,10-undecadiene, 1,11-dodecadiene, 1,12-tridecadiene, 1,13-tetradecadiene, etc. Can, it can be formed from one or more ethylenically / alpha-olefin / nonconjugated polyene.

  Among them, the non-conjugated polyene forming ethylene / α-olefin / non-conjugated polyene is 5-ethylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene, 7-methyl-1,6-octadiene, Crosslinking is one or more of 5-methyl-1,4-hexadiene, particularly one or more of 5-ethylidene-2-norbornene, dicyclopentadiene, 5-vinyl-2-norbornene. From the viewpoint of excellent reactivity with the agent.

In the ethylene / α-olefin / non-conjugated polyene, the molar ratio of ethylene: α-olefin having 3 to 20 carbon atoms is 90:10 to 40:60, particularly 80:20 to 50:50, flexibility. The resulting thermoplastic elastomer composition is preferred because the rubber elasticity is good.
Further, the iodine value (iodine value before crosslinking) of ethylene / α-olefin / non-conjugated polyene is in the range of 3 to 40, particularly 5 to 25, so that the mechanical strength and rubber elasticity of the thermoplastic elastomer composition are It is preferable because it becomes better. When a cross-linked product of ethylene / α-olefin / non-conjugated polyene having a lower iodine value is used, the mechanical strength of the molded product obtained from the thermoplastic elastomer composition tends to be inferior, while the iodine value is If a cross-linked product of ethylene / α-olefin / non-conjugated polyene higher than the range is used, the rubber elasticity of the thermoplastic elastomer composition is likely to be impaired. In addition, the "iodine value" as used in this specification means the iodine value measured by the method described in JIS K1525 4.7.

The crosslinked olefin rubber (I) is a crosslinked product of olefin rubber (I ₀ ) having a Mooney viscosity (ML _{1 + 4} , 100 ° C.) of 25 to 350, particularly 40 to 300, It is preferable because the molding processability of the thermoplastic elastomer composition is improved and the mechanical strength of the molded product obtained from the thermoplastic elastomer composition is increased.
As used herein, “Mooney viscosity (ML _{1 + 4} , 100 ° C.)” refers to a viscosity measured by the method described in JIS K6300.

  The degree of crosslinking of the crosslinked olefin rubber (I) constituting the thermoplastic elastomer composition of the present invention can be adjusted according to the polymer composition, use, etc. of the thermoplastic elastomer composition containing the crosslinked olefin rubber (I). However, in general, when a cross-linked olefin rubber is subjected to Soxhlet extraction treatment with cyclohexane for 10 hours, the mass ratio (gel fraction) of the gel remaining without being dissolved in cyclohexane is determined after the cross-linking before the extraction treatment. The degree of cross-linking is 80% or more, particularly 95% or more with respect to the mass of the olefinic rubber of the present invention, so that the thermoplastic elastomer composition of the present invention and the molded article comprising the same have higher strain recovery at high temperatures. It is preferable from the point of becoming good.

The addition polymerization block copolymer (II) constituting the thermoplastic elastomer composition of the present invention is a polymer block comprising at least one polymer block (A) comprising an aromatic vinyl compound unit and a conjugated diene compound unit. It is a block copolymer having at least one (B) and is at least crosslinked at the polymer block (A) portion.
The addition polymerization block copolymer (II) may not be crosslinked at the polymer block (B) part but may be crosslinked only at the polymer block (A) part, or the polymer block (A) part. And the polymer block (B) part may be cross-linked.
The addition polymerization block copolymer (II) crosslinked at least in the polymer block (A) portion introduces a C1-8 alkylstyrene unit into the polymer block (A), and the C1-8 alkylstyrene unit It is suitably obtained by forming a crosslinked structure in the polymer block (A).

  In the addition polymerization block copolymer (II), the polymer block (A) composed of aromatic vinyl compound units constitutes a hard segment, and the polymer block (B) composed of (hydrogenated) conjugated diene compound units is soft. It constitutes a segment. The addition polymerization block copolymer (II) used in the thermoplastic elastomer composition of the present invention has a C1-8 alkylstyrene unit in the polymer block (A) forming a hard segment, and a C1-8 alkylstyrene unit. Since the polymer block (A) is crosslinked by the thermoplastic elastomer composition of the present invention containing such an addition polymerization type block copolymer (II), the strain recovery at high temperature is excellent. And has good rubber-like properties.

  In the polymer block (A) having a C1-8 alkyl styrene unit, the C1-8 alkyl styrene unit may be present at the terminal of the polymer block (A), or the molecular chain of the polymer block (A). May exist in the middle of the polymer block (A), and may exist in both the terminal of the polymer block (A) and the middle of the molecular chain. Therefore, the polymer block (A) may be crosslinked at the terminal portion of the polymer block (A), may be crosslinked in the middle of the molecular chain of the polymer block (A), or may be heavy. It may be cross-linked both at the end of the combined block (A) and in the middle of the molecular chain.

Addition polymerization block copolymer (II) is a diblock copolymer (AB) having one polymer block (A) and one polymer block (B), and one polymer block (A). In the case of a triblock copolymer (B-A-B) having two polymer blocks (B) or a hydrogenated product thereof, the C1-8 alkyl styrene unit is one polymer block. It exists in (A), and a cross-linking bond is formed at that portion.
In addition, when the addition polymerization block copolymer (II) is a triblock or tetrablock multiblock copolymer having two or more polymer blocks (A) or a hydrogenated product thereof, two Only one of the above polymer blocks (A) may have a structure in which a C1-8 alkylstyrene unit is present and crosslinked at that portion, or two or more or all polymer blocks (A) A C1-8 alkylstyrene unit may be present in each of the polymer blocks, and a plurality of polymer blocks (A) may be cross-linked.

A polymer block (A) having no C1-8 alkylstyrene unit is represented by A ₀ , a polymer block (A) having a C1-8 alkylstyrene unit is represented by A ₁ , and a polymer block (B) is represented by B. When the addition polymerization block copolymer (II) is the aforementioned diblock copolymer, triblock copolymer or hydrogenated product thereof having only one polymer block (A), the addition polymerization block copolymer (II), cross-linked with at least a polymer block a ₁ moiety, or a diblock copolymer represented by a ₁ -B, triblock represented by B-a ₁ -B It is a polymer or its hydrogenated product. In this case, the addition polymerization block copolymer (II) may be cross-linked even in the polymer block (B) portion from the viewpoint that the rubber elasticity of the thermoplastic elastomer composition and the molded product made thereof is better. desirable.

In addition, when the addition polymerization block copolymer (II) is a triblock or more multiblock copolymer having two or more polymer blocks (A), for example, A crosslinked at least in the block A ₁ portion _1- B-A ₀ , A ₁ -B-A ₁ , A ₁ -B-A ₀ -B, A ₁ -B-A ₁ -B, A ₁ -A ₀ -B-A ₀ -A ₁ , A ₀ -A ₁ -BA ₁ -A ₀ , A ₁ -BA-A ₀ -BA ₁ , (A ₁ -B) j (j represents an integer of 3 or more), (A ₁ -B) k-A ₁ (k represents an integer of 2 or more), (B-A _1- ) m-B (m represents an integer of 2 or more), (A ₁ -B) nX (n is an integer of 2 or more) , X represents a coupling agent residue) and the like, and / or hydrogenated products thereof.

Among them, the addition polymerization type block copolymer (II) is a hydrogenated product of a triblock copolymer represented by A ₁ -BA ₁ and / or A ₁ crosslinked at least in the block A ₁ portion. The hydrogenated product of the pentablock copolymer represented by -A ₀ -BA ₀ -A ₁ improves the strain recovery properties at high temperatures of the thermoplastic elastomer composition and the molded article made thereof. This is preferable.

Among them, addition polymerized block copolymer (II) is to be at least a hydrogenated product of a triblock copolymer represented by A ₁ -B-A ₁ at block A ₁ moiety is crosslinked, crosslinking The effect of improving the physical properties due to the introduction of bonds is high, and the thermoplastic elastomer composition obtained and the molded article made from the composition are preferable because the strain recovery properties at high temperatures and the rubber-like properties become more excellent.

  In the polymer block (A), examples of the alkyl styrene constituting the C 1-8 alkyl styrene unit include, for example, o-alkyl styrene, m-alkyl styrene, p-alkyl styrene whose alkyl group has 1 to 8 carbon atoms. 2,4-dialkylstyrene, 3,5-dialkylstyrene, 2,4,6-trialkylstyrene, one or more of the hydrogen atoms of the alkyl group in the aforementioned alkylstyrenes are substituted with halogen atoms And halogenated alkylstyrenes. More specifically, examples of the alkylstyrene derivative constituting the C1-8 alkylstyrene unit include o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5-dimethyl. Styrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o -Propyl styrene, m-propyl styrene, p-propyl styrene, 2,4-dipropyl styrene, 3,5-dipropyl styrene, 2,4,6-tripropyl styrene, 2-methyl-4-ethyl styrene, 3 -Methyl-5-ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chlorome Styrene, 2,4-bis (chloromethyl) styrene, 3,5-bis (chloromethyl) styrene, 2,4,6-tri (chloromethyl) styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, p -Dichloromethylstyrene etc. can be mentioned.

  The polymer block (A) can have a unit consisting of one or more of the above-described alkyl styrene and halogenated alkyl styrene as C1-8 alkyl styrene units.

Among them, as the C1-8 alkylstyrene unit, a p-methylstyrene unit is preferable because it has excellent reactivity with the crosslinking agent (V) and can surely introduce a crosslinked structure into the polymer block (A).
When the number of carbon atoms of the alkyl group bonded to the benzene ring of the alkylstyrene unit is 9 or more, the reactivity with the crosslinking agent (V) is inferior and a crosslinked structure is hardly formed.

  The content ratio of C1-8 alkylstyrene units in the polymer block (A) is the mass of the polymer block (A) constituting the addition polymerization block copolymer (II) [addition polymerization block copolymer (II). Is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more with respect to the total mass of the polymer block (A) having 2 or more polymer blocks (A). Is more preferable. In the addition polymerization block copolymer (II), when the content ratio of the C1-8 alkylstyrene unit is less than 1% by mass with respect to the mass of the polymer block (A), the polymer block (A) is crosslinked at the portion. Bonds are not easily formed, and the thermoplastic elastomer composition containing such an addition polymerization block copolymer tends to be inferior in strain recovery at high temperatures. In some cases, all the units constituting the polymer block (A) may be composed of C1-8 alkylstyrene units, but the ease of production of the addition polymerization block copolymer (II), the thermoplastic elastomer From the viewpoint of molding processability of the composition, monomer cost, etc., the upper limit of the content ratio of the C1-8 alkylstyrene unit is the mass of the polymer block (A) constituting the addition polymerization block copolymer (II). It is preferably 90% by mass with respect to [the total mass when the addition polymerization block copolymer (II) has two or more polymer blocks (A)].

  The number (number) of crosslinks in the polymer block (A) portion of the addition polymerization block copolymer (II) is 2 or more per molecule of the addition polymerization block copolymer (II). preferable. The number of crosslinks in the polymer block (A) can be changed by adjusting the number of C1-8 alkylstyrene units introduced into the polymer block (A) and the amount of the crosslinking agent (V) used. it can.

  The polymer block (A) in the addition polymerization block copolymer (II) can have other aromatic vinyl compound units as well as C1-8 alkylstyrene units as the aromatic vinyl compound units constituting the block. Examples of other aromatic vinyl compound units include styrene, α-methylstyrene, β-methylstyrene, t-butylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, vinylnaphthalene, and vinylanthracene. And units derived from indene, acetonaphthylene, and the like, and may have one or more of these units. Of these, styrene units are preferred as other aromatic vinyl compound units.

  When the polymer block (A) has other aromatic vinyl compound units together with C1-8 alkylstyrene units, the bonding form of the C1-8 alkylstyrene units and other aromatic vinyl compound units is random, block Or a tapered block shape.

  The polymer block (A) has a small amount of structural units derived from other copolymerizable monomers, if necessary, together with the above C1-8 alkylstyrene units and / or other aromatic vinyl compound units. May be. In that case, the proportion of structural units derived from other copolymerizable monomers is preferably 30% by mass or less, and preferably 10% by mass or less, based on the total mass of the polymer block (A). More preferred. Examples of the other copolymerizable monomer in that case include ionic polymerizable monomers such as methacrylic acid ester, acrylic acid ester, 1-butene, pentene, hexene, butadiene, isoprene, and methyl vinyl ether. . The bonding form of these other copolymerizable monomers may be any form such as a random form, a block form, and a tapered block form.

  Examples of the conjugated diene compound constituting the polymer block (B) in the addition polymerization block copolymer (II) include isoprene, butadiene, hexadiene, 2,3-dimethyl-1,3-butadiene, and 1,3-pentadiene. Can be mentioned. The polymer block (B) may be composed of only one of these conjugated diene compounds or may be composed of two or more. When the polymer block (B) has a structural unit derived from two or more kinds of conjugated diene compounds, the bonding form thereof is random, tapered, block-like, or a combination of two or more thereof. Can be.

  Among them, the polymer block (B) is a polyisoprene block composed of monomer units mainly composed of isoprene units or a hydrogenated polyisoprene block obtained by hydrogenating a part or all of unsaturated bonds thereof; mainly composed of butadiene units. A polybutadiene block comprising monomer units or a hydrogenated polybutadiene block in which some or all of the unsaturated bonds thereof are hydrogenated; or an isoprene / butadiene copolymer block comprising monomer units mainly composed of isoprene units and butadiene units A hydrogenated isoprene / butadiene copolymer block in which part or all of the unsaturated bonds are hydrogenated is preferable from the viewpoint of weather resistance, heat resistance, and the like. In the isoprene / butadiene copolymer block, the molar ratio of isoprene unit: butadiene unit is preferably 1: 9 to 9: 1 from the viewpoint of improving the physical properties of rubber, and preferably 3: 7 to 7: 3. Is more preferable. In particular, the polymer block (B) is more preferably a hydrogenated block of the aforementioned polyisoprene block, polybutadiene block or isoprene / butadiene copolymer block.

  From the viewpoint that the heat resistance and weather resistance of the thermoplastic elastomer composition of the present invention and the molded product made from the composition are good, the addition polymerization block copolymer (II) is an unsaturated dimer in the polymer block (B). Part or all of the heavy bonds are preferably hydrogenated (hereinafter sometimes referred to as “hydrogenation”). In this case, the hydrogenation rate of the conjugated diene polymer block is preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 100 mol%.

  The polymer block (B) may have a small amount of structural units derived from other copolymerizable monomers as required, together with the conjugated diene compound unit. In this case, the proportion of the other copolymerizable monomer is preferably 30% by mass or less based on the total mass of the polymer block (B) constituting the addition polymerization block copolymer (II). More preferably, it is 10 mass% or less. Examples of other copolymerizable monomers in that case include ionic polymerizable monomers such as styrene and α-methylstyrene.

  The degree of crosslinking in the addition polymerization block copolymer (II) can be adjusted according to the polymer composition, use, etc. of the thermoplastic elastomer composition containing the addition polymerization block copolymer (II). Is a Soxhlet extraction treatment for 10 hours using cyclohexane with the addition polymerization block copolymer after crosslinking, and the mass ratio (gel fraction) of the gel remaining without being dissolved in cyclohexane is determined after the crosslinking before the extraction treatment. The degree of cross-linking is 80% or more with respect to the mass of the addition polymerization block copolymer (II), and the strain recovery property at high temperatures of the thermoplastic elastomer composition of the present invention and the molded product thereof is as follows. From the point which is excellent in it.

  The addition polymerization block copolymer (II) used in the present invention is crosslinked only at the conjugated diene polymer block portion in that a crosslink is formed in the polymer block (A) portion forming the hard segment. This is different from the conventional crosslinked product of a block copolymer comprising an aromatic vinyl compound polymer block / conjugated diene compound polymer block. In the present invention, by using the addition polymerization block copolymer (II) that is at least crosslinked at the polymer block (A) portion forming the hard segment, as described above, the strain recovery property at high temperature is improved. This makes it possible to provide a thermoplastic elastomer composition which is excellent and flexible and has good rubber properties.

The molecular weight of the addition polymerization block copolymer (II) is not particularly limited, but in a state before hydrogen addition and before dynamic crosslinking treatment [addition polymerization block copolymer (I ₀ ) before hydrogen addition] The number average molecular weight of the polymer block (A) is in the range of 2,500 to 75,000, preferably 5,000 to 50,000, and the number average molecular weight of the polymer block (B) is 10,000 to 300. The total number average of the addition polymerization block copolymer (II) [addition polymerization block copolymer (I ₀ ) before hydrogenation]] is within the range of 30,000 to 250,000 The molecular weight is in the range of 12,500 to 2,000,000, preferably 50,000 to 1,000,000, from the viewpoint of the mechanical properties and molding processability of the resulting thermoplastic elastomer composition. Suitable That. In addition, the number average molecular weight (Mn) as used in this specification says the value calculated | required from the standard polystyrene calibration curve by the gel permeation chromatography (GPC) method.

The thermoplastic elastomer composition of the present invention comprises a crosslinked olefin rubber (I) and an addition polymerization block copolymer (II), and a crosslinked olefin rubber (I): addition polymerization block copolymer (II) = 90. : 10 to 10:90 in a mass ratio, particularly 80:20 to 20:80 in a mass ratio is excellent in molding processability and flexibility, and strain after applying strain over a long period at high temperature This is preferable from the viewpoint of obtaining a thermoplastic elastomer composition and a molded article excellent in recoverability. The olefin rubber (I ₀ ), which is a precursor of the crosslinked olefin rubber (I), is larger than the addition polymerization block copolymer (II ₀ ), which is a precursor of the addition polymerization block copolymer (II). Since it is easily available and generally available at a low price, the content ratio of the crosslinked olefin rubber (I): addition polymerization block copolymer (II) in the thermoplastic elastomer composition of the present invention is 90: 10-50: 50, particularly 80:20 to 60:40, a thermoplastic elastomer composition and a molded article excellent in molding processability, flexibility, and strain recovery after being strained over a long period of time at a high temperature are more economical. Can be obtained smoothly at a reasonable cost.

The thermoplastic elastomer composition of the present invention contains a polyolefin (III) together with a crosslinked olefin rubber (I) and an addition polymerization block copolymer (II).
Examples of the polyolefin (III) include ethylene polymers, propylene polymers, polybutene-1 and poly-4-methylpentene-1, and one or more of these can be used. Among them, from the viewpoint of moldability, one or both of an ethylene polymer and a propylene polymer are preferably used as the polyolefin (III), and a propylene copolymer is particularly preferably used.

  Examples of the ethylene polymer preferably used as the polyolefin (III) include, for example, ethylene homopolymers such as high-density polyethylene, medium-density polyethylene, and low-density polyethylene, ethylene / butene-1 copolymer, and ethylene / hexene copolymer. Copolymer, ethylene / heptene copolymer, ethylene / octene copolymer, ethylene 4-methylpentene-1 copolymer, ethylene / vinyl acetate copolymer, ethylene / acrylic acid copolymer, ethylene / acrylic acid ester copolymer Examples thereof include ethylene copolymers such as a copolymer, an ethylene / methacrylic acid copolymer, and an ethylene / methacrylic acid ester copolymer, and one or more of these can be used. Of these, one or more of high density polyethylene, medium density polyethylene, and low density polyethylene is more preferably used from the viewpoint of moldability.

  Examples of the propylene polymer preferably used as polyolefin (III) include propylene homopolymer, ethylene / propylene random copolymer, ethylene / propylene block copolymer, propylene / butene-1 copolymer, and propylene. -An ethylene-butene-1 copolymer, a propylene- 4-methylpentene-1 copolymer, etc. can be mentioned, These 1 type (s) or 2 or more types can be used. Of these, one or more of a propylene homopolymer, an ethylene / propylene random copolymer, and an ethylene-propylene block copolymer are more preferably used from the viewpoint of moldability.

The thermoplastic elastomer composition of the present invention comprises 10 to 300 parts by mass of polyolefin (III) with respect to 100 parts by mass of the total of the crosslinked olefin rubber (I) and the addition polymerization block copolymer (II). It is necessary to contain. By containing 10 to 300 parts by mass of the polyolefin (III), the polyolefin (III) forms a continuous phase in the thermoplastic elastomer composition, and in the continuous phase, the crosslinked olefin rubber (I) and The addition polymerization block copolymer (II) formed by crosslinking at least in the polymer block (A) part has a fine particle dispersed morphology, strain recovery at high temperature, flexible rubber characteristics, Good moldability is imparted to the thermoplastic elastomer composition.
The thermoplastic elastomer composition obtained when the content of the polyolefin (III) is less than 10 parts by mass with respect to 100 parts by mass in total of the crosslinked olefin rubber (I) and the addition polymerization block copolymer (II) The thermoplasticity of the resin becomes insufficient, and the moldability becomes inferior. On the other hand, when it exceeds 300 parts by mass, the flexibility of the resulting thermoplastic elastomer composition is insufficient. The thermoplastic elastomer composition of the present invention comprises a crosslinked olefin rubber (I) and an addition polymerization block copolymer (II) from the viewpoint that the molding processability and flexibility of the thermoplastic elastomer composition and the molded article become better. It is more preferable that the polyolefin (III) is contained at a ratio of 12 to 200 parts by mass, particularly 14 to 100 parts by mass with respect to 100 parts by mass in total.

  The thermoplastic elastomer composition of the present invention may not contain the rubber softening agent (IV) or may contain the rubber softening agent (IV) as necessary. When the rubber softener (IV) is contained, the rubber softener (IV) is added in an amount of 300 parts by mass with respect to a total of 100 parts by mass of the crosslinked olefinic rubber (I) and the addition polymerization block copolymer (II). It is good to make it contain in the ratio below a part. When the content of the rubber softener (IV) exceeds 300 parts by mass, the rubber elastomer softening agent (IV) bleed-out, oil resistance, and mechanical properties are deteriorated in the thermoplastic elastomer composition and a molded article comprising the same. It becomes easy. The thermoplastic elastomer composition of the present invention is a cross-linked olefin from the viewpoint that the moldability and flexibility of a thermoplastic elastomer composition and a molded article comprising the same are improved, and that strain recovery and oil resistance at high temperatures are improved. Preferably, the rubber softening agent (IV) is contained in a proportion of 50 to 250 parts by mass with respect to 100 parts by mass in total of the system rubber (I) and the addition polymerization block copolymer (II). It is more preferable to contain in the ratio of 200 mass parts.

  The kind of rubber softener (IV) is not particularly limited, and any of mineral oil and / or synthetic resin can be used. Mineral oil softeners are generally a mixture of aromatic hydrocarbons, naphthenic hydrocarbons and paraffinic hydrocarbons, where the number of carbon atoms in the paraffinic hydrocarbons accounts for 50% or more of the total carbon atoms. It is called paraffinic oil, while naphthenic hydrocarbons with 30-45% carbon atoms are called naphthenic oils, and aromatic hydrocarbons with more than 35% carbon atoms are aromatic oils. is called. Among these, the rubber softener preferably used in the present invention is paraffinic oil.

  The paraffinic oil has a kinematic viscosity at 40 ° C. of 20 to 800 cst (centistokes), particularly 50 to 600 cst, a pour point of 0 to −40 ° C., particularly 0 to −30 ° C., and a flash point (COC method). Those having a temperature of 200 to 400 ° C., particularly 250 to 350 ° C. are preferably used. Examples of the synthetic resin softener include polybutene and low molecular weight polybutadiene, and any of them can be used.

The thermoplastic elastomer composition of the present invention can contain other thermoplastic polymers as long as the effects of the present invention are not impaired. Examples of other thermoplastic polymers that can be contained include polyphenylene ether resins; polyamide 6, polyamide 6 · 6, polyamide 6 · 10, polyamide 11, polyamide 12, polyamide 6 · 12, polyhexamethylenediamine terephthalamide, Polyamide resins such as polyhexamethylenediamine isophthalamide and xylene group-containing polyamide; Polyester resins such as polyethylene terephthalate and polybutylene terephthalate; Acrylic resins such as polymethyl acrylate and polymethyl methacrylate; Polyoxymethylene homopolymer, Polyoxymethylene resin such as polyoxymethylene copolymer; Styrene resin such as styrene homopolymer, acrylonitrile-styrene resin, acrylonitrile-butadiene-styrene resin Polycarbonate resin; styrene elastomer such as styrene / butadiene copolymer rubber and styrene / isoprene copolymer rubber and hydrogenated product or modified product thereof; natural rubber; synthetic isoprene rubber, liquid polyisoprene rubber and hydrogenated product thereof Chloroprene rubber; Acrylic rubber; Butyl rubber; Acrylonitrile butadiene rubber; Epichlorohydrin rubber; Silicone rubber; Chlorosulfonated polyethylene; Urethane rubber; Polyurethane elastomer; Polyamide elastomer; Polyester elastomer; Soft vinyl chloride resin, etc. Can be mentioned.
The content of the other polymer is preferably in a range where the flexibility and mechanical properties of the thermoplastic elastomer composition are not impaired, and relative to 100 parts by mass of the thermoplastic elastomer composition before adding the other polymer. The amount is preferably 200 parts by mass or less.

  The thermoplastic elastomer composition of the present invention can contain an inorganic filler as required. Examples of the inorganic filler that can be contained in the thermoplastic elastomer composition of the present invention include calcium carbonate, talc, clay, synthetic silicon, titanium oxide, carbon black, barium sulfate, mica, glass fiber, whisker, carbon fiber, and carbonic acid. Examples thereof include magnesium, glass powder, metal powder, kaolin, graphite, molybdenum disulfide, and zinc oxide, and one or more of these can be contained. The content of the inorganic filler is preferably within a range where the effects of the present invention are not impaired, and generally 50 parts by mass or less with respect to 100 parts by mass of the thermoplastic elastomer composition before adding the inorganic filler. Is preferred.

  Furthermore, the thermoplastic elastomer composition of the present invention is optionally provided with a light stabilizer, a heat stabilizer, an antifogging agent, a pigment, a flame retardant, an antistatic agent, a silicone oil, an antiblocking agent, an ultraviolet absorber, and an antioxidant. 1 type, or 2 or more types, such as an agent and a lubricant, can be contained. Among these, examples of the antioxidant include hindered phenols, hindered amines, phosphoruss, and sulfurs. Lubricants include fluorine, paraffin and hydrocarbon (paraffin wax, polyethylene wax, etc.), fatty acid (stearic acid, etc.), fatty acid amide (saturated fatty acid monoamide, unsaturated fatty acid monoamide, saturated fatty acid bisamide, unsaturated fatty acid bisamide, etc. ), Fatty acid ester (polyhydric alcohol fatty acid ester, saturated fatty acid ester, unsaturated fatty acid ester, ester wax, composite ester, etc.), metal soap, fatty acid ketone, silicone (organopolysiloxane, alkylpolysiloxane) Etc.

The thermoplastic elastomer composition of the present invention comprises an olefin rubber (I ₀ ), at least one polymer block (A) comprising an aromatic vinyl compound unit and a polymer block (B) comprising a conjugated diene compound unit. At least one addition polymerization block copolymer (II ₀ ) (crosslinking) selected from a block copolymer having at least one and having a C1-8 alkylstyrene unit in the polymer block (A) and a hydrogenated product thereof The previous addition polymerization block copolymer) is contained in a mass ratio of olefin rubber (I ₀ ): addition polymerization block copolymer (II ₀ ) = 90: 10 to 10:90, and the olefin rubber. 0 per 100 parts by weight of (I ₀₎ and the addition polymerized block copolymer (II _0), 10~300 parts by weight of the polyolefin (III), the rubber softener (IV) 00 parts by mass and a cross-linking agent (V) in a proportion of 0.1 to 20 parts by mass, and optionally by a method of dynamically cross-linking a mixture in which other polymers and additives described above are mixed under melting conditions. Can be manufactured. By adopting such a method, each component is uniformly mixed, and at least the olefin-based rubber has a cross-linking bond, and at the same time, the C1-8 alkyl in the polymer block (A) in the addition-polymerized block copolymer (II). The thermoplastic elastomer composition of the present invention having a cross-linked styrene unit can be produced smoothly.
Here, “dynamically cross-linking under melting conditions” in the present specification means cross-linking while applying shear stress to the mixture in a molten state by kneading.

The olefin rubber (I ₀ ) used in the production of the thermoplastic elastomer composition of the present invention is an olefin rubber that has not yet been crosslinked, and the crosslinked olefin rubber (I) constituting the thermoplastic elastomer composition. It is possible to use various olefin-based rubbers (particularly, the above-described ethylene / α-olefin copolymer rubber and / or ethylene / α-olefin / nonconjugated polyene copolymer rubber) before crosslinking described in the above-mentioned explanation. it can.

Olefin-based rubber (I ₀ ) has been widely sold and used as a kind of thermoplastic elastomer, and in the present invention, a commercial product may be purchased and used as it is, or an olefin-based rubber may be used for the present invention. Rubber (I ₀ ) may be produced and used.
The production method of the olefin rubber (I ₀ ) is not particularly limited, and can be produced by an appropriate method such as a gas phase polymerization method, a solution polymerization method, or a slurry polymerization method. These polymerization operations can be carried out either batchwise or continuously. In the solution polymerization method or slurry polymerization method, an inert hydrocarbon is usually used as a reaction medium. Examples of such inert hydrocarbon solvents include aliphatic hydrocarbons such as n-pentane, n-hexane, n-heptane, n-octane, n-decane, and n-dodecane; fats such as cyclohexane and methylcyclohexane. Cyclic hydrocarbons; aromatic hydrocarbons such as benzene, toluene and xylene. These hydrocarbon solvents can be used alone or in admixture of two or more. Moreover, a raw material monomer can also be utilized as a hydrocarbon solvent.

In the production of the olefin rubber (I ₀ ), for example, an olefin polymerization catalyst comprising a transition metal compound selected from V, Ti, Zr and Hf and an organometallic compound can be used as the polymerization catalyst. The transition metal compound and the organometallic compound may be used alone or in admixture of two or more. Particularly preferred examples of such an olefin polymerization catalyst include a metallocene compound composed of a metallocene compound and an organoaluminum compound or an ionic compound that reacts with the metallocene compound to form an ionic complex, or a vanadium compound and an organoaluminum compound. A Ziegler-Natta catalyst consisting of

The above-mentioned addition polymerization block copolymer (II ₀ ) used for the production of the thermoplastic elastomer composition of the present invention is an addition polymerization system in which the C1-8 alkylstyrene unit in the polymer block (A) is not yet crosslinked. Except for the point that it is a block copolymer, the addition-polymerized block copolymer (II) after the crosslinking described above constituting the thermoplastic elastomer composition and its contents (for example, constituting the block copolymer) The type and composition of the monomer to be used, molecular weight, etc.) are the same.

The production method of the addition polymerization type block copolymer (II ₀ ) before crosslinking used for the production of the thermoplastic elastomer composition of the present invention is not limited in any way, and the polymer block (A) has at least one C1-8 alkylstyrene unit. Any method may be adopted as long as it is a method capable of producing an addition polymerization block copolymer (II ₀ ) having a seed. For example, the addition polymerization block copolymer (II ₀ ) can be produced by performing a known polymerization method such as an ionic polymerization method such as anionic polymerization or cationic polymerization, or a radical polymerization method.
An addition polymerization block copolymer (II ₀ ) having a C1-8 alkylstyrene unit in the polymer block (A) is a polymer for producing the polymer block (A) in carrying out the above-mentioned known polymerization method. It can manufacture by using the alkylstyrene which has a C1-C8 alkyl group couple | bonded with the benzene ring as at least one part of an aromatic vinyl compound at a process.

As the crosslinking agent (V) for the dynamic crosslinking, it acts on the olefin rubber (I ₀ ) to form a crosslinking bond, and the polymer block (A ₀ ) of the addition polymerization block copolymer (I ₀ ) ) Are used which act on the C1-8 alkyl styrene units present in the structure to form a crosslink. As the cross-linking agent (V), during the dynamic cross-linking treatment under melting conditions, the cross-linking agent acts on the olefinic rubber (I ₀ ) to form a cross-linking bond, and the addition polymerization type block copolymer (II ₀ ) Any crosslinking agent that can act on the C1-8 alkylstyrene unit present in the polymer block (A) to form a crosslink in the polymer block (A) at that portion is not particularly limited. An appropriate crosslinking agent (V) can be selected in consideration of reactivity and the like according to the processing conditions (for example, processing temperature and processing time) during the dynamic cross-linking treatment. It is preferably used as a crosslinking agent (V).

When an organic peroxide is used as the cross-linking agent (V), the olefin rubber (I ₀ ) is cross-linked to form a cross-linked olefin rubber (I), and a polymer in the addition polymerization block copolymer (II ₀ ) An addition polymerization block copolymer (II) crosslinked with both the polymer block (A) portion and the polymer block (B) portion having block C1-8 alkylstyrene units is formed. In some cases, the polyolefin (III) is crosslinked.

Any organic peroxide can be used as the organic peroxide crosslinking agent, such as dicumyl peroxide, di-t-butyl peroxide, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, α, α′-bis (t-butylperoxy) diisopropylbenzene, 3,3,5-trimethylcyclohexane, n-butyl-4,4-bis (t-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, t-butylperoxybenzoate, t -Butylperoxyisopropyl carbonate, diacetyl peroxide, laur Peroxide, etc. can be exemplified t- butyl cumyl peroxide, may be used alone or two or more of them. Among these, 2,5-dimethyl-2,5-di (t-butylperoxy) hexane and dicumyl peroxide are preferably used from the viewpoint of reactivity.
In addition to the above-mentioned crosslinking agent (V), if necessary, a crosslinking accelerator comprising a disulfide compound such as benzothiazyl disulfide or tetramethylthiuram disulfide, tolyl isocyanurate, divinylbenzene, ethylene glycol dimethacrylate, A crosslinking aid such as a polyfunctional monomer such as triethylene glycol dimethacrylate may be used.

The amount of the crosslinking agent (V) used is preferably 0.1 to 20 parts by mass with respect to 100 parts by mass in total of the olefin rubber (I ₀ ) and the addition polymerization block copolymer (II ₀ ). More preferably, it is 0.5-10 mass parts. When the amount of the crosslinking agent (V) used is less than 0.1 parts by mass as described above, it becomes difficult to form a sufficient cross-linking bond in the olefin rubber and the polymer block (A), while the above-mentioned 20 parts by mass. If it is more than the part, bleeding out of the rubber softening agent (IV), deterioration of mechanical properties and the like are likely to occur.

The dynamic cross-linking treatment step under the melt conditions for producing the thermoplastic elastomer composition includes olefin rubber (I ₀ ), addition polymerization block copolymer (II ₀ ), polyolefin (III) or these 3 If necessary, the rubber softener (IV) and other components are melt-kneaded and finely and uniformly dispersed, and the cross-linking agent (V) causes cross-linking to the olefin rubber (I ₀ ). In the addition polymerization block copolymer (II ₀ ), at least a portion of the polymer block (A) is cross-linked, and the addition polymerization block copolymer (II ₀ ) is converted into its hard segment [polymer block ( A)] is converted into at least a cross-linked addition polymerization block copolymer (II). Even when a mixture containing an olefin rubber (I ₀ ), an addition polymerization block copolymer (II ₀ ), a polyolefin (III) and optionally a rubber softener (IV) is crosslinked, When the crosslinking treatment is performed under static conditions as in the vulcanization process, the polyolefin (III) is difficult to form a continuous phase, and thus the resulting composition tends to exhibit no thermoplasticity.

  As a device for performing dynamic crosslinking for producing the thermoplastic elastomer composition of the present invention, any of melt kneaders capable of uniformly mixing each component can be used, for example, a single screw extruder, a twin screw extruder, or the like. Machine, kneader, banbury mixer, etc. Among these, it is preferable to use a twin screw extruder that has a large shearing force during kneading and can be operated continuously.

Although not limited at all, the following method can be mentioned as a specific example of the processing process at the time of manufacturing a thermoplastic elastomer composition using an extruder. That is, an olefin rubber (I ₀ ), an addition polymerization block copolymer (II ₀ ), a polyolefin (III), and optionally a rubber softener (IV) are mixed and charged into a hopper of an extruder. At that time, polyolefin (III), rubber softener (IV) and cross-linking agent (V) are added to olefin rubber (I ₀ ) and addition polymerization block copolymer (II ₀ ) from the beginning, or Some or all of them are added from the middle of the extruder, melt kneaded and extruded. In that case, you may melt-knead sequentially in steps using two or more extruders.
The melt kneading temperature is appropriately selected within a range in which the olefin rubber (I ₀ ), the addition polymerization block copolymer (II ₀ ) and the polyolefin (III) are melted and the crosslinking agent (V) reacts. Usually, it is preferably 160 ° C to 270 ° C, more preferably 180 ° C to 240 ° C. The melt kneading time is preferably about 30 seconds to 5 minutes.

  The thermoplastic elastomer composition of the present invention obtained by the dynamic cross-linking treatment under the melting condition as described above is a cross-linked olefin-based rubber (matrix phase) in a continuous phase (matrix phase) made of thermoplastic polyolefin (III). I), a flexible phase composed of an addition polymerization block copolymer (II) crosslinked at least in the polymer block (A) portion generally has a unique morphology (dispersed form) finely dispersed. Yes. The dispersed particle size of the finely dispersed phase is preferably 0.1 μm to 30 μm, and more preferably 0.1 μm to 10 μm. However, the present invention is not limited thereto, and the phase composed of the crosslinked olefin rubber (I) and the phase composed of the addition polymerization block copolymer (II) and the phase composed of the polyolefin (III) form a co-continuous phase. Also good. Also in this case, the composition obtained can be made excellent in thermoplasticity by appropriately selecting the use amount and kneading conditions of the crosslinking agent (V).

  The thermoplastic elastomer composition of the present invention obtained as described above can be molded by using a method such as injection molding, extrusion molding or subsequent blow molding to obtain a molded product.

  EXAMPLES The present invention will be specifically described below with reference to examples and comparative examples, but the present invention is not limited to the following examples. In the following examples, measurement of each physical property and evaluation of the quality of a molded product were performed as follows.

(1) Measurement of hardness (JIS-A):
A press sheet made of the thermoplastic elastomer composition obtained in the example or the comparative example was stacked on a predetermined thickness (12 mm), and A hardness was measured according to JIS-K6253.

(2) Measurement of compression set:
After being left for 22 hours or 1000 hours under the conditions of a temperature of 120 ° C. and a compression deformation of 25% according to JIS-K6262, using a press sheet comprising the thermoplastic elastomer composition obtained in the examples or comparative examples. The compression set of was measured.

(3) Bleed out:
When the press sheet made of the thermoplastic elastomer composition obtained in Examples or Comparative Examples is left at 70 ° C. for 24 hours, and the rubber softener (IV) is not bleeded out to the sheet surface and touched by hand. The case where there was no slime was evaluated as good (O), and the case where the rubber softener (IV) bleeded out on the sheet surface and was touched by hand was evaluated as poor (x).

(4) Measurement of gel fraction 1 g of each sample obtained in Reference Examples 1 to 5 was subjected to Soxhlet extraction treatment with cyclohexane for 10 hours. After the extraction treatment, the extraction residue was separated and dried in vacuum, and the mass of the extraction residue Was measured, and the mass percentage relative to the mass (1 g) immediately before the extraction treatment was determined as the gel fraction.

The contents of the olefin rubber (I ₀ ), polyolefin (III), rubber softener (IV) and crosslinking agent (V) used in the following Examples, Comparative Examples or Reference Examples are as follows.
○ Olefin rubber (I ₀ ):
Olefin-based elastomer (ethylene / α-olefin / non-conjugated polyene copolymer rubber) [“JSR EP37F” manufactured by JSR Corporation; iodine value 8, Mooney viscosity (ML _{1 + 4,} 100 ° C.) 100]
○ Polyolefin (III):
Polypropylene (Random Copolymer) [“Grand Polypro B221” manufactured by Sumitomo Mitsui Polyolefin Co., Ltd., MFR = 1 g / 10 min (temperature 230 ° C., 2.16 kg load)]
○ Rubber softener (IV):
Paraffinic process oil [“PW-380” manufactured by Idemitsu Kosan Co., Ltd.]
○ Crosslinking agent (V-1):
2,5-Dimethyl-2,5-di (t-butylperoxy) hexane [Nippon Yushi Co., Ltd. "Perhexa 25B-40"]
○ Crosslinking agent (V-2):
N, N′-m-phenylene bismaleimide [“Barunok PM” manufactured by Ouchi Shinsei Chemical Co., Ltd.]

<< Production Example 1 >> [Production of Polymerized Block Copolymer (II ₀ )]
(1) In a pressure vessel equipped with a stirrer, 2700 g of cyclohexane, 70 g of a monomer mixture obtained by mixing p-methylstyrene / styrene = 30/70 (mass ratio), and a 1.3 mol cyclohexane solution of sec-butyllithium 2.52 ml was added and polymerized at 50 ° C. for 120 minutes, and then 326.6 g of a monomer mixture mixed at a ratio of isoprene / butadiene = 60/40 (mass ratio) was added and polymerized for 120 minutes. Further, 70 g of a monomer mixture mixed at a ratio of p-methylstyrene / styrene = 30/70 (mass ratio) was added, and after polymerization for 120 minutes, methanol was added to terminate the polymerization, and poly (p-methylstyrene) / Styrene) -poly (isoprene / butadiene) -poly (p-methylstyrene / styrene) type triblock copolymer was obtained.
(2) A cyclohexane solution of the triblock copolymer obtained in (1) above is prepared and charged into a pressure-resistant vessel that has been sufficiently purged with nitrogen, and then a Ni / Al Ziegler hydrogenation catalyst is used. A hydrogenation reaction was carried out at 80 ° C. for 5 hours in a hydrogen atmosphere, and poly (p-methylstyrene / styrene) -hydrogenated poly (isoprene / butadiene) -poly (p-methylstyrene / styrene) type triblock copolymer [ Mn = 200,000; ratio of each polymer block = 15/70/15 (mass ratio); hydrogenation rate of poly (isoprene / butadiene) block = 99 mol%] [addition polymerization block copolymer (II ₀ )] Was produced.

<< Production Example 2 >> [Production of Addition Polymerization Block Copolymer (2)]
(1) 30 kg of cyclohexane, 700 g of styrene monomer and 20 ml of 1.3 mol cyclohexane solution of sec-butyllithium were added in a pressure vessel equipped with a stirrer and polymerized at 50 ° C. for 60 minutes, and then 63 g of tetrahydrofuran and 2600 g of butadiene monomer. In addition, it was polymerized for 120 minutes. Further, 700 g of a styrene monomer was added and polymerized for 60 minutes, and then methanol was added to terminate the polymerization to obtain a polystyrene-polybutadiene-polystyrene type triblock copolymer.
(2) A cyclohexane solution of the triblock copolymer obtained in (1) above is prepared and charged into a pressure-resistant vessel that has been sufficiently purged with nitrogen, and then a Ni / Al Ziegler hydrogenation catalyst is used. A hydrogenation reaction was performed at 80 ° C. for 5 hours in a hydrogen atmosphere, and a polystyrene-hydrogenated polybutadiene-polystyrene type triblock copolymer [Mn = 260,000; the ratio of each polymer block = 17.5 / 65/17. 5 (mass ratio): hydrogenation rate of polybutadiene block = 99 mol%] [addition polymerization block copolymer (2)] was produced.

<< Production Example 3 >> [Production of poly (p-methylstyrene)]
In a pressure-resistant vessel equipped with a stirrer, 2700 g of cyclohexane, 300 g of p-methylstyrene monomer and 2.9 ml of 1.3 mol cyclohexane solution of sec-butyllithium were added and polymerized at 50 ° C. for 120 minutes, and then methanol was added for polymerization. And poly (p-methylstyrene) (Mn = 60,000) was obtained.

<< Production Example 4 >> [Polystyrene Production]
In a pressure-resistant vessel with a stirrer, 2700 g of cyclohexane, 300 g of styrene monomer and 2.9 ml of 1.3 mol cyclohexane solution of sec-butyllithium were added, polymerized for 120 minutes at 50 ° C., then methanol was added to stop the polymerization. Polystyrene (Mn = 60,000) was obtained.

<< Production Example 5 >> [Production of Hydrogenated Polybutadiene]
Add 2700 g of cyclohexane, 6.05 g of tetrahydrofuran, 300 g of butadiene monomer, and 4.35 ml of 1.3 mol cyclohexane solution of sec-butyllithium in a pressure vessel equipped with a stirrer, polymerize at 50 ° C. for 120 minutes, and then add methanol. The polymerization was stopped to obtain polybutadiene. After preparing a cyclohexane solution of this polybutadiene and charging it into a pressure-resistant vessel that has been sufficiently purged with nitrogen, a hydrogenation reaction is carried out at 80 ° C. for 5 hours in a hydrogen atmosphere using a Ni / Al Ziegler hydrogenation catalyst. Hydrogenated polybutadiene [Mn = 10,000] was obtained.

<< Examples 1-5 >>
(1) Olefin rubber (I ₀ ), addition polymerization block copolymer (II ₀ ) produced in Production Example 1, polyolefin (III), rubber softener (IV), crosslinking agent (V-1) and After preliminarily mixing the crosslinking aid (triallyl isocyanurate) at the ratio shown in Table 1 below, the mixture is supplied to a twin-screw extruder [manufactured by Technobel Corp.] and melted at a temperature of 160 to 200 ° C. and a rotation speed of 200 rpm. By kneading, thermoplastic elastomer compositions were produced.
(2) Using the thermoplastic elastomer composition obtained in (1) above, using a press molding machine [single-acting compression molding machine “NSF-37” manufactured by Shinto Metal Industry Co., Ltd.] The molded article (press sheet) of 150 mm × 150 mm × 1 mm was produced by molding at a mold temperature of 210 ° C., and each physical property of the obtained molded article was measured by the method described above. As shown in Examples 1-5.

<< Comparative Examples 1-5 >>
(1) Olefin rubber (I ₀ ), addition polymerization block copolymer (2) produced in Production Example 2, polyolefin (III), rubber softener (IV), crosslinking agent (V-1) and crosslinking An auxiliary agent (triallyl isocyanurate) was premixed at the ratio shown in Table 2 below, and then supplied to a twin-screw extruder [manufactured by Technobel Co., Ltd.] and melt kneaded at a temperature of 160 to 200 ° C. and a rotation speed of 200 rpm. Thus, a thermoplastic elastomer composition was produced.
(2) Using the thermoplastic elastomer composition obtained in (1) above, using a press molding machine [single-acting compression molding machine “NSF-37” manufactured by Shinto Metal Industry Co., Ltd.] The molded product (press sheet) of 150 mm × 150 mm × 1 mm was manufactured by molding at a mold temperature of 210 ° C., and each physical property of the obtained molded product was measured by the method described above. It was as shown.

<< Comparative Examples 6-9 >>
(1) Olefin rubber (I ₀ ), addition polymerization block copolymer (2) produced in Production Example 2, polyolefin (III), rubber softener (IV), crosslinking agent (V-1) or ( V-2) and a crosslinking aid (triallyl isocyanurate or dibenzothiazyl disulfide) were premixed at a ratio shown in Table 3 below, and then supplied to a twin-screw extruder [manufactured by Technobel Co., Ltd.] A thermoplastic elastomer composition was produced by melt-kneading at 160 to 200 ° C. and a rotation speed of 200 rpm.
(2) Using the thermoplastic elastomer composition obtained in (1) above, using a press molding machine [single-acting compression molding machine “NSF-37” manufactured by Shinto Metal Industry Co., Ltd.] The molded product (press sheet) of 150 mm × 150 mm × 1 mm was manufactured by molding at a mold temperature of 210 ° C., and each physical property of the obtained molded product was measured by the method described above. It was as shown.

  As can be seen from the results of Table 1 above, the molded articles made of the thermoplastic elastomer compositions of Examples 1 to 5 are excellent in strain recovery after being compressed at a high temperature, and particularly as long as 1000 hours at a high temperature of 120 ° C. The compression set after compression over time is as small as 38 to 45%, and the strain recovery property after applying strain over a long period at high temperature is extremely excellent. Moreover, the molded articles obtained from the thermoplastic elastomer compositions of Examples 1 to 5 have no bleeding out of the rubber softening agent (IV) and are excellent in appearance and touch.

On the other hand, as can be seen from the results in Table 2 above, the thermoplastic elastomer compositions of Comparative Examples 1 to 3 are crosslinked olefin rubber (I), polyolefin (which is a crosslinked product of olefin rubber (I ₀ ), polyolefin ( Comparative Example 4 contains III) and a rubber softener (IV), but does not contain an addition polymerization block copolymer (II) that is at least crosslinked in the polymer block (A) portion. The thermoplastic elastomer composition of -5 is a cross-linked olefin rubber (I) that is a cross-linked product of olefin rubber (I ₀ ), addition polymerization block copolymer (2), polyolefin (III), and rubber softening Contains an agent (IV) but is not cross-linked at the styrene polymer block portion of the addition polymerization block copolymer (2). Large compression set after condensation, is inferior to the strain recovery after the addition of strain for a long time at high temperatures. In addition, the molded articles made of the thermoplastic elastomer compositions of Comparative Examples 2 and 3 cause bleeding out of the rubber softener (IV).

Further, as seen in the results of Table 3 above, the thermoplastic elastomer compositions of Comparative Examples 6 to 9 are the crosslinked olefin rubber (I), which is a crosslinked product of the olefin rubber (I ₀ ), and the addition polymerization block. It contains copolymer (2), polyolefin (III), and rubber softener (IV), but is not crosslinked at the styrene polymer block portion of addition polymerization block copolymer (2). Even after being compressed at high temperature for 22 hours, the compression set is already large, and the strain recoverability after applying strain at high temperature is poor.

<< Reference Examples 1-6 >>
Olefin rubber (I ₀ ), addition polymerization block copolymer (II ₀ ) produced in Production Example 1, addition polymerization block copolymer (2) produced in Production Example 2, and poly produced in Production Example 3 (P-methylstyrene), the polystyrene produced in Production Example 4 or the hydrogenated polybutadiene produced in Production Example 5, a rubber softener (IV), a crosslinking agent (V-1) and a crosslinking aid (triallyl isocyanurate) ) Was preliminarily mixed at the ratio shown in Table 4 below, and then supplied to a lab plast mill [manufactured by Toyo Seiki Co., Ltd.] and melt-kneaded at a temperature of 200 ° C. to produce a sample.
When the gel fraction of this sample was measured by the method described above, it was as shown in Table 4 below.

As can be seen from the results of Table 4 above, the olefin rubber (I ₀ ), the addition polymerization block copolymer (II ₀ ), poly (p-methylstyrene) or hydrogenated polybutadiene and the crosslinking agent (V-1) In Reference Examples 1 to 4 and 6, which were melt kneaded and added, all had a high gel fraction, and an addition polymerization block copolymer having an olefin rubber (I ₀ ) and a C1-8 alkylstyrene unit. (II ₀ ), addition polymerization block copolymer (2), poly (p-methylstyrene) having a C1-8 alkylstyrene unit, and hydrogenated polybutadiene were all crosslinked with an organic peroxide.
On the other hand, in Reference Example 5 using polystyrene which does not have a C1-8 alkylstyrene unit (p-methylstyrene unit), a cross-linking agent (V-1) is added to perform dynamic treatment (melting). When kneading), the gel fraction is zero.
From these results, it was confirmed that the olefin rubber (I ₀ ) becomes a cross-linked olefin rubber (I) when dynamically crosslinked under melting conditions using an organic peroxide crosslinking agent. In the block copolymer of the polymer block (A) having a styrene unit and the polymer block (B) [addition polymerization block copolymer (II ₀ )], an organic peroxide cross-linking agent is used for melting conditions. It was confirmed that both the polymer block (A) and the polymer block (B) were cross-linked by dynamically cross-linking with.

The thermoplastic elastomer composition of the present invention is excellent in molding processability, strain recovery at high temperature, particularly strain recovery after applying strain over a long period of time at high temperature, and has flexible and good rubber characteristics. Therefore, for example, various industrial vehicles such as automobiles, construction machinery vehicles / agricultural machinery vehicles / railway vehicles, machine tools / construction machinery / agricultural machinery / mining machinery / industrial robots / chemical / pharmaceutical plants / chemical transfer machinery / foods It can be suitably used for a wide range of applications such as various industrial and mining machines such as industrial machines and hydraulic tools, ships, medical fields, and miscellaneous goods.

Claims (4)

(I) From a structural unit derived from a crosslinked olefin rubber (I) and at least one polymer block (A) composed of a structural unit derived from an aromatic vinyl compound and a conjugated diene compound optionally hydrogenated A block copolymer having at least one polymer block (B) and having a structure derived from alkylstyrene in which at least one alkyl group having 1 to 8 carbon atoms is bonded to the benzene ring in the polymer block (A) An addition polymerization block copolymer (II) having a unit and crosslinked at least with the polymer block (A) is converted into a crosslinked olefin rubber (I): addition polymerization block copolymer (II) = 90: In a mass ratio of 10 to 10:90; and
(Ii) For a total of 100 parts by mass of the cross-linked olefin rubber (I) and the addition polymerization block copolymer (II);
10 to 300 parts by weight of polyolefin (III); and
300 parts by mass or less of rubber softener (IV);
A thermoplastic elastomer composition characterized by comprising:   The thermoplastic elastomer composition according to claim 1, wherein the structural unit derived from alkylstyrene contained in the polymer block (A) of the addition polymerization block copolymer (II) is a structural unit derived from p-methylstyrene. A polymer comprising at least one polymer block (A) comprising a structural unit derived from an olefinic rubber (I ₀ ) and an aromatic vinyl compound and a structural unit derived from a conjugated diene compound which may be hydrogenated A block copolymer having at least one block (B), wherein the polymer block (A) has a structural unit derived from alkylstyrene in which at least one alkyl group having 1 to 8 carbon atoms is bonded to a benzene ring. The addition polymerization block copolymer (II ₀ ) is contained at a mass ratio of olefin rubber (I ₀ ): addition polymerization block copolymer (II ₀ ) = 90: 10 to 10:90, and olefinic For a total of 100 parts by mass of rubber (I ₀ ) and addition polymerization block copolymer (II ₀ );
10 to 300 parts by mass of polyolefin (III);
300 parts by weight or less of rubber softener (IV); and
0.1 to 20 parts by mass of the crosslinking agent (V);
2. The method for producing a thermoplastic elastomer composition according to claim 1, wherein the mixture containing at a ratio of 2 is dynamically crosslinked under melting conditions. A molded article comprising the thermoplastic elastomer composition according to claim 1.