JP2007169564A - Thermoplastic elastomer composition and molded product thereof - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a flexible thermoplastic elastomer excellent in rubber elasticity at elevated temperatures and heat resistance, and giving an extrusion molded product of good surface appearance, and to provide such a molded product. <P>SOLUTION: The thermoplastic elastomer composition comprises 100 pts.mass of (I) an addition polymerization-based block copolymer having at least one polymer block (A) composed of vinyl aromatic compound units and at least one polymer block (B) composed of (hydrogenated) conjugated diene compound units, wherein this block copolymer is ionomer-crosslinked at least the polymer block (A), 10-300 pts.mass of (II) a polyolefin and 300 pts.mass or less of (III) a flexibilizer for rubber. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a thermoplastic elastomer composition containing a specific cross-linked addition polymerization block copolymer and a polyolefin, and a molded article thereof. The thermoplastic elastomer composition of the present invention is excellent in strain recovery at high temperatures and can provide a molded product having a good surface appearance.

  In recent years, various thermoplastic elastomers are widely used in the fields of automobiles, medical / pharmaceuticals, foods, and the like. Among such thermoplastic elastomers, a hydrogenated block copolymer having a polymer block made of a vinyl aromatic compound and a polymer block made of a conjugated diene compound (hereinafter referred to as “hydrogenated block copolymer”) There are proposals of compositions using (sometimes abbreviated) (see Patent Documents 1 and 2). For example, an elastomeric composition obtained by blending a hydrogenated block copolymer with a hydrocarbon oil, an olefin polymer, or the like is crosslinked using a crosslinking agent such as an organic peroxide and a crosslinking aid, and the resulting elastomeric composition is obtained. Proposals have been made to improve the rubber elasticity (compression set) at high temperatures.

  However, in the above composition, only the soft segment composed of the conjugated diene compound block of the hydrogenated block copolymer is crosslinked, so that the rubber elasticity at 100 ° C. or higher is insufficient, and vulcanized rubber is used. The level of low compression set at high temperatures that has been achieved has not been reached. This is because, when the compression set test temperature is equal to or higher than the glass transition point (Tg) of the vinyl aromatic block, the binding force of the polymer block made of the vinyl aromatic compound is weakened. This is because the contribution of the hard segment to the rubber elasticity decreases.

  Further, when the above composition contains a coarse crosslinked product made of a hydrogenated block copolymer, there is a problem that the surface property of a molded product obtained by extrusion molding is deteriorated. The crosslinked product is produced by crosslinking in an insufficiently dispersed state in the olefin polymer during the production of the thermoplastic elastomer composition. Once the crosslinked structure is formed, the crosslinked product is incorporated into the olefin polymer. It has the property that dispersion | distribution of it becomes more difficult.

In addition, some of the essential components of the thermoplastic elastomer composition of the present invention described in detail below are disclosed in, for example, Patent Document 3 regarding the basic structure.
JP 59-131613 A JP 2000-109640 A JP 2003-20383 A

  An object of the present invention is to provide a thermoplastic elastomer composition which is flexible and excellent in rubber elasticity and heat resistance at high temperature and excellent in the surface appearance of an extrusion-molded product, and a molded product thereof.

  The present inventors have intensively studied to solve the above problems. As a result, in a block copolymer having one or more polymer blocks composed of vinyl aromatic compound units and one or more polymer blocks composed of conjugated diene compound units, a heavy segment comprising a hard segment composed of vinyl aromatic compound units is formed. When it is made into a structure that is at least ionomer-crosslinked in the coalesced block portion, it is found that the surface property of the molded product is improved by being excellent in strain recovery at high temperatures (heat resistance) and excellent in fluidity during melt molding, The present invention has been completed.

That is, the present invention
[1] At least one polymer block (A) composed of a vinyl aromatic compound unit having 1% by mass or more of an alkylstyrene derivative unit (a) having at least one alkyl group bonded to a benzene ring and hydrogenated. An addition polymerization block copolymer having at least one polymer block (B) composed of a good conjugated diene compound unit, wherein at least the polymer block (A) is ionomer-crosslinked. 100 parts by mass of (I);
10 to 300 parts by mass of polyolefin (II); and
300 parts by mass or less of rubber softener (III);
A thermoplastic elastomer composition comprising:
[2] At least one polymer block (A) composed of a vinyl aromatic compound unit having 1% by mass or more of an alkylstyrene derivative unit (a) having at least one alkyl group bonded to a benzene ring and hydrogenated. 100 parts by mass of an addition polymerization type block copolymer (I ₀ ) having one or more polymer blocks (B) composed of good conjugated diene compound units;
10 to 300 parts by mass of polyolefin (II);
300 parts by mass or less of rubber softener (III);
0.01 to 20 parts by mass of radical initiator (IV); and
0.01 to 20 parts by mass of a divalent or higher metal unsaturated organic acid salt (V);
The thermoplastic elastomer composition according to the above [1], which is obtained by dynamically treating a mixture containing the molten mixture,
[3] The thermoplastic elastomer composition according to the above [1] or [2], wherein the alkylstyrene derivative unit (a) is a p-methylstyrene unit,
[4] The thermoplastic elastomer composition according to the above [2] or [3], wherein the unsaturated organic acid salt (V) of a divalent or higher metal is zinc dimethacrylate or zinc diacrylate,
[5] A molded product comprising the thermoplastic elastomer composition according to any one of [1] to [4], and [6] a molded product according to [5], which is an extrusion molded product,
About.

  According to the present invention, there are provided a thermoplastic elastomer composition which is flexible and excellent in rubber elasticity and heat resistance at high temperature and excellent in the surface appearance of an extruded molded product, and a molded product thereof.

The present invention is described in detail below.
The addition polymerization block copolymer (I) constituting the base component in the thermoplastic elastomer composition of the present invention comprises a polymer block (A) composed of vinyl aromatic compound units and a polymer composed of conjugated diene compound units. It is a block copolymer having one or more combined blocks (B), and at least ionomer cross-linking is performed at the polymer block (A) portion forming a hard segment.

  The addition polymerization block copolymer (I) may not be crosslinked at the polymer block (B) portion but may be ionomer-crosslinked only at the polymer block (A) portion, or the polymer block (A). Both the portion and the polymer block (B) portion may be ionomer-crosslinked.

The addition polymerization block copolymer (I) that is ionomer-crosslinked at least in the polymer block (A) portion has 1% by mass or more of an alkylstyrene derivative unit (a) in which at least one alkyl group is bonded to a benzene ring. Addition-polymerization block copolymer having one or more polymer blocks (A) composed of vinyl aromatic compound units and one or more polymer blocks (B) composed of conjugated diene compound units optionally hydrogenated ( It is preferable that an ionomer crosslinked structure is formed by dynamically treating a radical initiator (IV) and an unsaturated organic acid salt (V) of a divalent or higher metal with I ₀ ) under melting conditions.

  In the addition polymerization block copolymer (I), the polymer block (A) composed of vinyl aromatic compound units constitutes a hard segment, and the polymer block (B) constitutes a soft segment. The addition polymerization block copolymer (I) suitably used in the thermoplastic elastomer composition of the present invention has a polymer block by having an alkylstyrene derivative unit (a) in a polymer block (A) forming a hard segment. Since the (A) portion is ionomer-crosslinked, the thermoplastic elastomer composition of the present invention containing such an addition-polymerized block copolymer (I) has excellent strain recovery at high temperatures and good rubber. Characteristics and good moldability.

The addition polymerization block copolymer (I) is a diblock copolymer (AB) having one polymer block (A), and a triblock copolymer (B-) having one polymer block (A). In the case of AB) or a hydrogenated product thereof, the alkylstyrene derivative unit (a) is present in the one polymer block (A), and an ionomer crosslink is formed at that portion.
In addition, when the addition polymerization block copolymer (I) is a triblock having two or more polymer blocks (A), a tetrablock or more multiblock copolymer or a hydrogenated product thereof, two or more Alternatively, the alkyl styrene derivative unit (a) may be present in all the polymer blocks (A), and a plurality of polymer blocks (A) may be ionomer-crosslinked.

The polymer block (A) not having the alkylstyrene derivative unit (a) is A ₀ , the polymer block (A) having the alkylstyrene derivative unit (a) is A ₁ , and the polymer block (B) is B In other words, when the addition polymerization block copolymer (I) is the above-described diblock copolymer, triblock copolymer or hydrogenated product thereof having only one polymer block (A), addition polymerization is performed. The system block copolymer (I) is a diblock copolymer represented by A ₁ -B, which is crosslinked at least in the polymer block A ₁ portion, or a triblock represented by B-A ₁ -B. It is a block copolymer or its hydrogenated product. In this case, the addition polymerization block copolymer (I) is desirably crosslinked at the polymer block (B) portion from the viewpoint of improving rubber elasticity.

In addition, when the addition polymerization block copolymer (I) is a triblock or more multiblock copolymer having two or more polymer blocks (A), for example, A cross-linked 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 -B-a 1 -A} 0, a 1 -B-a 0 -B-a 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. May be.

Among them, the addition polymerization block copolymer (I) is a hydrogenated product of a triblock copolymer represented by A ₁ -B-A ₁ crosslinked at least in the block A ₁ portion. The effect of improving physical properties due to the introduction of bonds is high, and the thermoplastic elastomer composition of the present invention is preferable because of high strain recovery properties at high temperatures and good rubber-like properties.

Examples of the alkyl styrene constituting the alkyl styrene derivative unit (a) in the polymer block (A) include o-alkyl styrene, m-alkyl styrene, p-alkyl styrene, 2,4-dialkyl styrene, 3, 5 -Dialkyl styrene, 2,4,6-trialkyl styrene, halogenated alkyl styrenes in which one or more hydrogen atoms of the alkyl group in the above alkyl styrenes are substituted with halogen atoms, etc. .
More specifically, examples of the alkylstyrene derivative constituting the alkylstyrene derivative unit (a) include o-methylstyrene, m-methylstyrene, p-methylstyrene, 2,4-dimethylstyrene, 3,5- Dimethylstyrene, 2,4,6-trimethylstyrene, o-ethylstyrene, m-ethylstyrene, p-ethylstyrene, 2,4-diethylstyrene, 3,5-diethylstyrene, 2,4,6-triethylstyrene, o-propylstyrene, m-propylstyrene, p-propylstyrene, 2,4-dipropylstyrene, 3,5-dipropylstyrene, 2,4,6-tripropylstyrene, 2-methyl-4-ethylstyrene, 3-methyl-5-ethylstyrene, o-chloromethylstyrene, m-chloromethylstyrene, p-chloro Methylstyrene, 2,4-bis (chloromethyl) styrene, 3,5-bis (chloromethyl) styrene, 2,4,6-tri (chloromethyl) styrene, o-dichloromethylstyrene, m-dichloromethylstyrene, Examples thereof include alkylstyrene derivatives in which the α-position carbon of the alkyl group such as p-dichloromethylstyrene is a methyl group or a methylene group.

  The polymer block (A) can have a unit composed of one or more of alkyl styrene and halogenated alkyl styrene as the alkyl styrene derivative unit (a).

  Among them, as the alkylstyrene derivative unit (a), the hydrogen atom of the α-position carbon atom of the alkyl group bonded to the benzene ring is excellent in reactivity with the radical initiator (IV), and is a divalent or higher metal. Since an ionomer crosslinked structure can be reliably introduced into the polymer block (A) via the unsaturated organic acid salt (V), a p-methylstyrene unit is preferred.

  The content ratio of the alkylstyrene derivative unit (a) in the polymer block (A) of the addition polymerization block copolymer (I) is the mass of the polymer block (A) [addition polymerization block copolymer (I) is In the case of having two or more polymer blocks (A), the total mass] is preferably 1% by mass or more, more preferably 5% by mass or more, and more preferably 10% by mass or more. Further preferred. In some cases, all the units constituting the polymer block (A) may be composed of the alkylstyrene derivative unit (a). When the content ratio of the alkylstyrene derivative unit (a) is less than 1% by mass with respect to the mass of the polymer block (A), it is difficult to form an ionomer cross-linking bond in the polymer block (A) portion, The thermoplastic elastomer composition containing the addition polymerization block copolymer (I) tends to be inferior in strain recovery at high temperatures.

  The addition polymerization block copolymer (I) can have other vinyl aromatic compound units other than the alkylstyrene derivative unit (a) as the vinyl aromatic compound units constituting the polymer block (A). Examples of other vinyl aromatic compound units include styrene, α-methylstyrene, β-methylstyrene, monofluorostyrene, difluorostyrene, monochlorostyrene, dichlorostyrene, methoxystyrene, vinylnaphthalene, vinylanthracene, indene, and acetonaphthylene. The unit which consists of these can be mentioned, and can have these 1 type, or 2 or more types of units. Of these, styrene units are preferred as other vinyl aromatic compound units.

  When the polymer block (A) has another vinyl aromatic compound unit together with the alkyl styrene derivative unit (a), the bonding form of the alkyl styrene derivative unit (a) and the other vinyl aromatic compound unit is random. The shape may be any of a block shape, a tapered block shape, and the like.

  The polymer block (A) may have a small amount of a structural unit composed of another copolymerizable monomer as necessary, together with the structural unit derived from the vinyl aromatic compound. In that case, the proportion of the structural units composed of other copolymerizable monomers is preferably 30% by mass or less, more preferably 10% by mass or less, based on the total mass of the polymer block (A). preferable. 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, or a tapered block form.

  In the addition polymerization block copolymer (I), the conjugated diene compound units constituting the polymer block (B) include isoprene, butadiene, hexadiene, 2,3-dimethyl-1,3-butadiene, 1,3- Mention may be made of units composed of pentadiene and the like. The polymer block (B) may be composed of only one kind of these conjugated diene compound units or may be composed of two or more kinds. 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 saturated bonds are hydrogenated is preferable from the viewpoint of weather resistance, heat resistance, etc., and the above-mentioned polyisoprene block, polybutadiene block or isoprene / butadiene copolymer is preferable. The And more preferably Tsu a hydrogenated block of click. In particular, 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 the effect of improving rubber properties, and is preferably 3: 7 to 7: 3. It is more preferable.

  The polymer block (B) of the addition polymerization block copolymer (I) from the viewpoint that the heat resistance and weather resistance of the thermoplastic elastomer composition containing the addition polymerization block copolymer (I) are good. It is preferable that a part or all of the unsaturated double bonds in is hydrogenated (hereinafter sometimes referred to as “hydrogenation”). The hydrogenation rate of the conjugated diene polymer block at that time is preferably 60 mol% or more, more preferably 80 mol% or more, and further preferably 95 mol%.

  The polymer block (B) may have a small amount of a structural unit composed of another copolymerizable monomer as necessary, together with a structural unit composed of a conjugated diene. In that case, the ratio 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 (I). 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 molecular weight of the addition polymerization block copolymer (I) is not particularly limited, but the number average molecular weight of the polymer block (A) is 2,500 to 75, in the state (I ₀ ) before the dynamic ionomer crosslinking treatment. 000, preferably 5,000 to 50,000, and the polymer block (B) has a number average molecular weight of 10,000 to 300,000, preferably 30,000 to 250,000. The total number average molecular weight of the addition polymerization block copolymer (I ₀ ) is 12,500 to 2,000,000, preferably 50,000 to 1,000,000. The thermoplastic elastomer composition is suitable in terms of mechanical properties, moldability, and the like. 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.

  In the addition polymerization block copolymer (I), the degree of crosslinking, that is, the proportion of the alkylstyrene derivative unit (a) and the reaction with the radical initiator (IV) and the unsaturated organic acid salt (V) of a divalent or higher metal. The degree can be adjusted according to the polymer composition and use of the thermoplastic elastomer composition containing the addition polymerization block copolymer (I), but in general, the addition polymerization block copolymer after ionomer crosslinking is used. Was subjected to Soxhlet extraction treatment with tetrahydrofuran for 1 hour, and the mass ratio (gel fraction) of the gel remaining without being dissolved in tetrahydrofuran was determined by the addition-polymerized block copolymer (I) after crosslinking before the extraction treatment. It is preferable that the degree of crosslinking is 80% or more with respect to the mass from the viewpoint of excellent strain recovery at high temperatures.

  The addition polymerization type block copolymer (I) in the thermoplastic elastomer composition of the present invention has a conjugated diene-based heavy polymer in that an ionomer cross-linking bond is formed in the polymer block (A) portion forming the hard segment. This is different from a conventional crosslinked product of a block copolymer comprising a polymer block comprising a polymer block comprising a conjugated diene compound unit / a polymer block comprising a vinyl aromatic compound unit having a crosslinked polymer block portion. In the thermoplastic elastomer composition of the present invention, by using the addition polymerization block copolymer (I) that is at least ionomer-crosslinked at the polymer block (A) part forming the hard segment, as described above, at a high temperature. The present invention makes it possible to provide a thermoplastic elastomer composition excellent in strain recovery, flexible and good rubber properties, and excellent in molding processability, and a molded product thereof.

  Examples of the polyolefin (II) used in the thermoplastic elastomer composition of the present invention include an ethylene polymer, a propylene polymer, polybutene-1 and poly-4-methylpentene-1, and one of these or Two or more kinds can be used. Among them, as the polyolefin (II), an ethylene polymer and / or a propylene polymer are preferably used, and a propylene copolymer is more preferably used from the viewpoint of moldability.

  Examples of the ethylene polymer that is preferably used as the polyolefin (II) 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 an ethylene copolymer such as a polymer, an ethylene / methacrylic acid copolymer, and an ethylene / methacrylic acid ester copolymer. Among these, high-density polyethylene, medium-density polyethylene, and / or low-density polyethylene are more preferably used from the viewpoint of moldability.

  Examples of the propylene polymer preferably used as polyolefin (II) 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. Among these, a propylene homopolymer, an ethylene / propylene random copolymer and / or an ethylene-propylene block copolymer are more preferably used from the viewpoint of moldability.

  The thermoplastic elastomer composition of the present invention needs to contain 10 to 300 parts by mass of polyolefin (II) with respect to 100 parts by mass of the addition polymerization block copolymer (I). By containing the polyolefin (II) in the proportion of 10 to 300 parts by mass, the polyolefin (II) forms a continuous phase in the thermoplastic elastomer composition, and at least the polymer block (A) is contained in the continuous phase. Addition-polymerization block copolymer (I) formed by ionomer cross-linking at the part has a morphology in which it is dispersed in the form of fine particles, and has high strain recovery at high temperatures, flexible rubber characteristics, and good moldability. Applied to the plastic elastomer composition.

  If the content of the polyolefin (II) is less than 10 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I), the thermoplastic elastomer composition to be obtained has insufficient thermoplasticity, and molding processing is performed. It 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 is a ratio of 12 to 200 parts by mass of polyolefin (II) with respect to 100 parts by mass of addition polymerization block copolymer (I) from the viewpoint of moldability and flexibility. It is preferable to contain in the ratio of 14-100 mass parts, and it is more preferable to contain.

  The kind of rubber softener (III) contained in the thermoplastic elastomer composition of the present invention as needed 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 contains a rubber softener (III) in a proportion of 300 parts by mass or less with respect to 100 parts by mass of the addition polymerization block copolymer (I), and 50 to 250 It is preferable to contain in the ratio of a mass part. When the content of the rubber softener (III) with respect to 100 parts by mass of the addition polymerization block copolymer (I) exceeds 300 parts by mass, the rubber softener (III) bleed-out, and the thermoplastic elastomer composition and The mechanical properties of the molded product made from it are lowered.

  As the radical initiator (IV) preferably used for the ionomer cross-linking treatment of the addition polymerization block copolymer (I), it acts on the alkylstyrene derivative unit (a) present in the polymer block (A) to react with benzyl. It is not particularly limited as long as it can form a radical and can be added to a double bond in an unsaturated organic acid salt (V) of a metal having a valence of 2 or more, and examples thereof include organic peroxides.

  Examples of the organic peroxide include dicumyl peroxide, di-t-butyl peroxide, α, α′-bis (t-butylperoxy) diisopropylbenzene, 2,5-dimethyl-2,5-di (t-butyl). Peroxy) hexane, 2,5-dimethyl-2,5-di (t-butylperoxy) hexyne-3, 1,3-bis (t-butylperoxyisopropyl) benzene, 1,1-bis (t-butylperoxy) -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 Royl peroxide, t-butylcumyl peroxide and the like can be mentioned, and one or more of these can be used. Among these, α, α'-bis (t-butylperoxy) diisopropylbenzene and 2,5-dimethyl-2,5-di (t-butylperoxy) hexane are preferably used from the viewpoint of reactivity and odor.

The amount of the radical initiator (IV) is an addition polymerized block copolymer _(I 0) 0.01 to 20 parts by weight per 100 parts by weight, is preferably from 0.01 to 10 parts by weight . When the amount of the radical initiator (IV) used is less than 0.01 parts by mass as described above, sufficient radicals cannot be generated in the alkylstyrene derivative unit (a) in the polymer block (A). When the amount is more than 20 parts by mass, bleeding out of the rubber softening agent (III), a decrease in mechanical properties of the thermoplastic elastomer composition and a molded product made of the same occur.

  Examples of the metal constituting the unsaturated organic acid salt (V) of a divalent or higher metal preferably used in the thermoplastic elastomer composition of the present invention include divalent alkalis such as calcium, magnesium, strontium and barium. Examples include earth metals, divalent transition metals such as zinc, copper, manganese, nickel, and cobalt, trivalent alkaline earth metals such as aluminum, and trivalent transition metals such as cobalt, iron, and chromium. It is done. On the other hand, an ethylenically unsaturated carboxylic acid is mentioned as an unsaturated organic acid which comprises the unsaturated organic acid salt (V) of a bivalent or more metal. Of these, zinc dimethacrylate and zinc diacrylate are preferred from the viewpoint of reactivity.

The amount of the divalent or higher metal unsaturated organic acid salt (V) used is 0.01 to 20 parts by mass with respect to 100 parts by mass of the addition polymerization block copolymer (I ₀ ), and 0.01 to It is preferably 10 parts by mass. When the amount of the unsaturated organic acid salt (V) of the metal having a valence of 2 or more is less than 0.01 parts by mass, the strain recovery at a high temperature is insufficient, while it is more than 20 parts by mass. As a result, the rubber softener (III) bleeds out.

The thermoplastic elastomer composition of the present invention can contain other 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 resins; ethylene-propylene copolymer rubber (EPM), ethylene-based elastomers such as ethylene-propylene-nonconjugated diene copolymer rubber (EPDM); styrene-butadiene copolymer rubber, styrene-isoprene copolymer rubber, etc. Styrenic elastomer and hydrogenated product or modified product thereof; natural rubber; synthetic isoprene rubber, liquid polyisoprene rubber and hydrogenated product or modified 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, and the like.
The content of the other thermoplastic polymer is preferably within the range in which the flexibility and mechanical properties of the thermoplastic elastomer composition are not impaired, and is 200 mass with respect to 100 mass parts of the addition polymerization block copolymer (I). It is preferably less than or equal to parts.

  Moreover, the thermoplastic elastomer composition of this invention can contain an inorganic filler as needed. 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 is generally 50 parts by mass or less with respect to 100 parts by mass of the addition polymerization block copolymer (I). Is preferred.

  Furthermore, the thermoplastic elastomer composition of the present invention is optionally a crosslinking aid, light stabilizer, heat stabilizer, antifogging agent, pigment, flame retardant, antistatic agent, lubricant, silicone oil, antiblocking agent, 1 type (s) or 2 or more types, such as a ultraviolet absorber and antioxidant, can be contained. Among these, examples of the crosslinking aid include triallyl isocyanurate, and examples of the antioxidant include hindered phenols, hindered amines, phosphorus and sulfur.

In the thermoplastic elastomer composition of the present invention, an addition polymerization block copolymer (I) in which a continuous phase (matrix phase) composed of thermoplastic polyolefin (II) is ionomer-crosslinked at least in the polymer block (A) portion. ), Or a flexible phase consisting of the addition polymerization block copolymer (I) and the rubber softener (III) has a unique morphology (dispersed form) finely dispersed. It is preferable. 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 to this, and the phase composed of the addition polymerization block copolymer (I) and the rubber softener (III) and the phase composed of the polyolefin (II) may form a co-continuous phase. .

  The thermoplastic elastomer composition of the present invention is prepared by previously preparing an addition polymerization block copolymer (I) crosslinked at least with an ionomer at the polymer block (A) portion, and then crosslinking the addition polymerization block copolymer (I). To 100 parts by mass, 10 to 300 parts by mass of polyolefin (II), 300 parts by mass or less of rubber softener (III) and optionally other polymers and additives described above are mixed and heat-kneaded. May be manufactured.

However, the thermoplastic elastomer composition of the present invention has one or more polymer blocks (A) composed of vinyl aromatic compound units and one or more polymer blocks (B) composed of conjugated diene compound units, and At least one addition polymerization block copolymer (I ₀ ) selected from a block copolymer having an alkylstyrene derivative unit (a) in the polymer block (A) and a hydrogenated product thereof (addition polymerization system before crosslinking) 10 to 300 parts by mass of polyolefin (II), 300 parts by mass or less of rubber softener (III), and 0.01 to 20 parts by mass of radical initiator (IV) with respect to 100 parts by mass of block copolymer) And an unsaturated organic acid salt (V) of a divalent or higher metal in a proportion of 0.01 to 20 parts by mass, and optionally further mixed with other polymers and additives described above. It is preferred that the mixture be produced by a method of dynamically processed in the molten condition. By adopting such a method, each component is uniformly mixed, and further contains an addition polymerization block copolymer (I) ionomer-crosslinked with an alkylstyrene derivative unit (a) in the polymer block (A). The thermoplastic elastomer composition of the present invention can be produced smoothly.

  Here, “dynamically treated under melting conditions” in the present specification means that the mixture in a molten state is reacted while applying a shear stress by kneading.

The above addition-polymerization block copolymer (I ₀ ) used for the production of the thermoplastic elastomer composition of the present invention comprises a metal block having an alkylstyrene derivative unit (a) in the polymer block (A) that is still divalent or higher. Except for the point that it is an addition polymerization block copolymer that is not radically reacted with the saturated organic acid salt (V), the addition polymerization after crosslinking described above constituting the thermoplastic elastomer composition of the present invention. It is the same in the system block copolymer (I) and its contents (for example, the kind and composition of monomers constituting the block copolymer, molecular weight, etc.).

The production method of the addition polymerization type block copolymer (I 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 an alkylstyrene derivative unit (a). Any method may be adopted as long as the method can produce the addition polymerization block copolymer (I ₀ ). For example, the addition polymerization block copolymer (I 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 (I ₀ ) having an alkylstyrene derivative unit (a) in the polymer block (A) is used for producing the polymer block (A) in performing the above-described known polymerization method. It can manufacture by using the alkylstyrene which has the alkyl group couple | bonded with the benzene ring as at least one part of a vinyl aromatic compound at a superposition | polymerization process.

The dynamic processing step under melting conditions for producing the thermoplastic elastomer composition of the present invention includes addition polymerization block copolymer (I ₀ ) and polyolefin (II), or softening for rubber with these two. The agent (III) is melt-kneaded and finely and uniformly dispersed, and the addition polymerization block copolymer (I ₀ ) is further added by the radical initiator (IV) and the unsaturated organic acid salt (V) of a metal having a valence of 2 or more. In which at least the polymer block (A) is ionomer-crosslinked with each other, and the addition polymerization block copolymer (I ₀ ) is at least ionomer-crosslinked with the hard segment [polymer block (A)]. It is converted into the system block copolymer (I).

  As an apparatus for performing dynamic processing under melting conditions for producing the thermoplastic elastomer composition of the present invention, any of melt-kneading apparatuses capable of uniformly mixing each component can be used, for example, uniaxial Examples thereof include an extruder, a twin screw extruder, a kneader, and a Banbury mixer. 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 dynamic processing method at the time of manufacturing the thermoplastic elastomer composition of this invention using an extruder.
First, the addition polymerization block copolymer (I ₀ ) and polyolefin (II) are mixed and charged into a hopper of an extruder. At that time, the polyolefin (II), the radical initiator (IV), the rubber softener (III), and the unsaturated organic acid salt (V) of a divalent or higher metal were added to the addition polymerization block copolymer (I _0). ) From the beginning, or part or all of them are added from the middle of the extruder and 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 the range of ± 30 ° C. of the 1-minute half-life temperature of the radical initiator (IV) when the addition polymerization block copolymer (I ₀ ) and the polyolefin (II) are melted. 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 treatment under the melting conditions as described above contains at least a polymer block (A) in a continuous phase (matrix phase) composed of thermoplastic polyolefin (II). ) Part of the addition polymerization block copolymer (I) cross-linked with an ionomer, or a flexible phase consisting of the addition polymerization block copolymer (I) and the rubber softener (III), It generally has a unique morphology (dispersed form) that is dispersed. The dispersed particle diameter 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 to this, and the phase composed of the addition polymerization block copolymer (I) and the rubber softener (III) and the phase composed of the polyolefin (II) may form a co-continuous phase. . In this case as well, the composition obtained is excellent in thermoplasticity by appropriately selecting the amount of radical initiator (IV) or divalent or higher metal unsaturated organic acid salt (V) used and kneading conditions. It can be.

  The thermoplastic elastomer composition obtained as described above can be molded by using a method such as injection molding, extrusion molding or subsequent blow molding, for example, to obtain a molded product. Among these, the thermoplastic elastomer composition of the present invention can exhibit the features of the most favorable surface appearance in extrusion molding.

  In extrusion molding, the thermoplastic elastomer composition used in the present invention is usually melted, given a shape through a die, and then water-cooled or air-cooled to form a molded product. As the extruder, a single-screw or multi-screw extruder can be used, and a multilayer sheet obtained by multilayer extrusion using a plurality of extruders can be formed. Moreover, it can also shape | mold directly from the extruder at the time of thermoplastic elastomer composition manufacture.

  Molded articles made of the thermoplastic elastomer composition of the present invention include various vehicle fields such as automobiles, construction machinery vehicles, agricultural machinery vehicles, railway vehicles, and ship fields; machine tools, construction machinery, agricultural machinery, mining machinery, industrial robots, It can be suitably used in the fields of chemical plants, chemical transfer machines, food industry machines, various engineering and mining machines such as hydraulic tools, and medical and pharmaceutical fields.

  EXAMPLES Hereinafter, although an Example etc. demonstrate this invention concretely, this invention is not limited by it at all. Moreover, the measurement and evaluation in the following examples etc. 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 the A hardness was measured according to JIS K6253.

(2) Measurement of tensile strength at break, tensile elongation at break, 100% modulus, 300% modulus:
The press sheet obtained in the example or comparative example was punched into No. 3 dumbbell shape, and using an autograph (manufactured by Shimadzu Corporation), the tensile breaking strength and the tensile breaking at 500 mm / min according to JIS K6253 The elongation was measured.

(3) Measurement of compression set:
Compression set after being left for 22 hours under the conditions of a temperature of 120 ° C. and a compression deformation of 25% in accordance with JIS K6253 using a press sheet comprising the thermoplastic elastomer composition obtained in the examples or comparative examples. Was measured.

(4) Evaluation of molded product appearance:
The height difference of the irregularities on the surface of the cut cross section perpendicular to the surface of the molded product obtained in the example or the comparative example was observed using an optical microscope and evaluated according to the following evaluation criteria.
A: Height difference is less than 10 μm ○: Height difference is 10 μm or more and less than 20 μm ×: Height difference is 20 μm or more

(5) Measurement of gel fraction:
1 g of the sample obtained in the reference example is subjected to Soxhlet extraction treatment with tetrahydrofuran for 1 hour. After the extraction treatment, the extraction residue is separated and dried in vacuum, the mass of the extraction residue is measured, and the mass of the sample before the extraction treatment is measured. The mass% was determined and used as the gel fraction.

(7) Measurement of tear strength:
Using the press sheet made of the thermoplastic elastomer composition obtained in the examples or comparative examples, the tear strength was measured by a right angle tearing method according to JIS K7128-3.

Addition polymerization block copolymer (I), polyolefin (II), rubber softener (III), radical initiator (IV), and divalent or higher unsaturated metal used in the following Examples and Comparative Examples The contents of the acid salt (V) are as follows.
○ Addition polymerization block copolymer (I ₀ ):
Poly (p-methylstyrene) -hydrogenated polybutadiene-poly (p-methylstyrene) type triblock copolymer [Mn = 230,000; ratio of each polymer block = 15/70/15 (mass ratio); polybutadiene Hydrogenation rate of block = 99 mol%]
○ Polyolefin (II):
Polypropylene (Random copolymer) [Sumitomo Mitsui Polyolefin "Grand Polypro B101", melt flow rate = 1 g / 10 min]
○ Rubber softener (III):
Paraffinic process oil (“PW-380” manufactured by Idemitsu Kosan Co., Ltd.)
○ Radical initiator (IV):
α, α′-bis (t-butylperoxy) diisopropylbenzene [“Perbutyl P” manufactured by NOF Corporation]
○ Unsaturated organic acid salt (V) of bivalent or higher metal:
Zinc dimethacrylate (Sartomer SR-708, manufactured by Sartomer)
○ Poly (p-methylstyrene):
Mn = 60,000
○ Crosslinking aid:
Triallyl isocyanurate (Nippon Kasei Co., Ltd.)
○ Crosslinking agent:
Neopentyl glycol dimethacrylate (Wako Pure Chemical Industries, Ltd.)

<< Examples 1 and 2 and Comparative Examples 1 and 2 >>
Addition polymerization block copolymer (I ₀ ), polyolefin (II), rubber softener (III), radical initiator (IV), divalent or higher metal unsaturated organic acid salt (V) and crosslinking aid Are premixed at the ratios shown in Table 1 below, and then supplied to a twin screw extruder (manufactured by Technobel) and melt-kneaded at a temperature of 160 to 200 ° C. and a rotation speed of 200 rpm to produce thermoplastic elastomer compositions, respectively. did.
The obtained thermoplastic elastomer composition was molded using a press molding machine (single-acting compression molding machine “NSF-37” manufactured by Shin-Fuji Metal Industry Co., Ltd.) at a mold temperature of 210 ° C. and 150 mm × When a molded product (press sheet) of 150 mm × 1 mm was produced and each physical property of the obtained molded product was measured by the method described above, it was as shown in Table 1 below.
Moreover, the obtained thermoplastic elastomer composition is extruded from a Garvey extrusion test die according to ASTM-D2230 under a condition of 200 ° C. using a single screw extruder to produce an extruded product having a wedge-shaped cross-sectional shape. Then, when the surface of the obtained extruded product was evaluated, it was as shown in Table 1 below.

<< Reference Example 1 >>
After pre-mixing poly (p-methylstyrene), radical initiator (IV) and unsaturated organic acid salt (V) of a metal having a valence of 2 or more in the proportions shown in Table 1 below, a batch kneader (Toyo The sample was manufactured by melting and kneading at a temperature of 200 ° C. and a rotation speed of 200 rpm, and the gel fraction of the sample was measured by the method described above. It was as shown.

  As can be seen from the results in Table 1 above, the molded article made of the thermoplastic elastomer composition obtained in Examples 1 and 2 was softer than the molded article made of the thermoplastic elastomer composition obtained in Comparative Example 2. It is understood that the surface properties are excellent. Further, from Reference Example 1, it was confirmed that poly (p-methylstyrene) was ionomer-crosslinked by kneading with a radical initiator (IV) and an unsaturated organic acid salt (V) of a metal having a valence of 2 or more. .

  The thermoplastic elastomer composition of the present invention is excellent in strain recovery (heat resistance) at high temperatures, is flexible and has good rubber properties, and has good surface properties of molded articles. Various industrial vehicles such as construction machinery vehicles, agricultural machinery vehicles, railway vehicles, machine tools, construction machinery, agricultural machinery, mining machinery, industrial robots, chemical plants, chemical transfer machinery, food industry machinery, hydraulic tools, etc. It can be suitably used in fields such as mining machinery and ships.

Claims (6)

One or more polymer blocks (A) comprising a vinyl aromatic compound unit having 1% by mass or more of an alkylstyrene derivative unit (a) in which at least one alkyl group is bonded to a benzene ring, and a hydrogenated conjugate An addition polymerization block copolymer having at least one polymer block (B) comprising a diene compound unit, wherein the addition polymerization block copolymer (I) is ionomer-crosslinked at least in the polymer block (A) portion. 100 parts by mass;
10 to 300 parts by mass of polyolefin (II); and
300 parts by mass or less of rubber softener (III);
A thermoplastic elastomer composition comprising the composition. One or more polymer blocks (A) comprising a vinyl aromatic compound unit having 1% by mass or more of an alkylstyrene derivative unit (a) in which at least one alkyl group is bonded to a benzene ring, and a hydrogenated conjugate 100 parts by mass of an addition polymerization block copolymer (I ₀ ) having at least one polymer block (B) comprising a diene compound unit;
10 to 300 parts by mass of polyolefin (II);
300 parts by mass or less of rubber softener (III);
0.01 to 20 parts by mass of radical initiator (IV); and
0.01 to 20 parts by mass of a divalent or higher metal unsaturated organic acid salt (V);
The thermoplastic elastomer composition according to claim 1, wherein the mixture is dynamically processed under melting conditions.   The thermoplastic elastomer composition according to claim 1 or 2, wherein the alkylstyrene derivative unit (a) is a p-methylstyrene unit.   The thermoplastic elastomer composition according to claim 2 or 3, wherein the divalent or higher metal unsaturated organic acid salt (V) is zinc dimethacrylate or zinc diacrylate.   A molded article comprising the thermoplastic elastomer composition according to any one of claims 1 to 4. The molded product according to claim 5, which is an extruded product.