JP2010007011A - Thermoplastic elastomer composition and method for producing it - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a thermoplastic elastomer composition, which has excellent mechanical properties, heat resistance, oil resistance, and flexibility and can give a molded product with good appearance, a method for producing the thermoplastic elastomer composition, and tubes, electric wires and cables obtained by using the thermoplastic elastomer composition. <P>SOLUTION: The thermoplastic elastomer composition is obtained by mixing a thermoplastic polyester elastomer (A) with a mixture composition (D) consisting of an acrylic rubber (B) and an acrylic oligomer (C) having two or more double bonds in the molecule. A weight ratio (A)/(D) of the component (A) to the component (D) is from 60/40 to 90/10. In a continuous phase of the component (A), the cross-linked component (D) is dispersed. The method for producing the thermoplastic elastomer composition, and the tubes, electric wires and cables obtained by using the thermoplastic elastomer composition are also provided. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a thermoplastic elastomer composition used for covering an electronic control wire harness and the like and a method for producing the same.

  Electronic control wire harnesses in automobiles, aircraft, and the like are used in environments exposed to various oils such as insulating oil and machine oil at high temperatures. For this reason, insulation wires, heat-shrinkable tubes, etc. used for covering the wires and cables that make up the wire harness, bundling wires and cables, protecting wires and cable ends, etc. (hereinafter referred to as “thin molded products”) As a material, a molded article of a thermoplastic polyester elastomer having excellent mechanical properties and heat resistance and oil resistance is used.

  The thermoplastic polyester elastomer has a crystalline hard segment formed by repeating units of aromatic polyester and the like, and a soft segment formed by repeating units of aliphatic polyether and aliphatic polyester in the polymer main chain. It is a multiblock copolymer having. Thermoplastic polyester elastomers are rich in moldability, and the molded product has excellent mechanical properties, heat resistance and oil resistance. In particular, when a thermoplastic polyester elastomer is crosslinked by irradiation or the like, high heat resistance and oil resistance can be imparted. On the other hand, however, there is a problem that the hardness is high and the flexibility is poor.

  Therefore, methods for increasing the soft segment content in the polyester elastomer (Non-patent Document 1) and adding a softener such as a plasticizer are known for improving flexibility (Patent Document 1). . However, in the method of increasing the content of the soft segment in the polyester elastomer, the melting point of the obtained resin composition is decreased, the elastic modulus is greatly decreased at high temperature, and the high temperature usable temperature range is decreased. There's a problem. In addition, the method of adding a softener such as a plasticizer has a problem that the softener is extracted or volatilized over time and the flexibility is lowered. Furthermore, there is also a problem that the surface condition of the molded product is deteriorated and the appearance is deteriorated by bleeding of the plasticizer.

Patent Document 2 discloses a thermoplastic elastomer composition comprising a thermoplastic polyester elastomer and a dynamically crosslinked rubber component. According to this composition, it is stated that flexibility and the like can be improved while maintaining the mechanical properties and heat resistance which are the characteristics of the polyester elastomer. Here, as the rubber component, a mixture of a diene rubber and an acrylic rubber is used.
Japanese Patent Laid-Open No. 10-330605 JP-A-7-97507 Yasuhiro Nishihara, “The Journal of Japan Rubber Association”, 299-303, Vol. 76, No. 8 (2003)

  However, the rubber component has low dispersibility in the polyester elastomer. In particular, acrylic rubber has low viscosity and thus has low dispersibility during mixing. Thus, a thermoplastic elastomer composition comprising a rubber component dynamically crosslinked with a polyester elastomer tends to be in a state where relatively large rubber lumps are dispersed non-uniformly in the polyester elastomer. And the unevenness | corrugation arises on the surface of a molded product, and the problem that the external appearance of a molded product is impaired tends to arise. In particular, when a thin-walled molded product such as an insulating tube is manufactured by extrusion molding at a high speed, the thickness of the molded product tends to vary and the appearance tends to deteriorate, and this problem is remarkable.

  The present invention provides a molded article with improved flexibility and good appearance, such as an insulating tube and a heat shrinkable tube, without impairing the excellent mechanical properties, heat resistance, and oil resistance of the thermoplastic polyester elastomer. It is an object of the present invention to provide a thermoplastic elastomer composition that can be manufactured and a method for producing the same. The present invention further provides a tube, an electric wire / cable obtained from the thermoplastic elastomer composition.

  As a result of intensive studies to solve the above problems, the present inventors finely dispersed a mixture of acrylic rubber and an acrylic oligomer having two or more double bonds in the molecule in the thermoplastic polyester elastomer, Moreover, by crosslinking this mixture, a so-called sea-island structure in which the crosslinked acrylic rubber is uniformly and finely dispersed in the polyester elastomer is obtained, giving a molded article having a good appearance, and further, this molded article is ionized. It discovered that the thermoplastic elastomer composition which was further excellent in mechanical characteristics, heat resistance, oil resistance, and a softness | flexibility by bridge | crosslinking by irradiation of a radiation was obtained, and completed this invention.

The present invention
Heat obtained by mixing a thermoplastic polyester elastomer (A) and an acrylic rubber (B) and a mixed composition (D) comprising an acrylic oligomer (C) having two or more double bond groups in the molecule. A plastic elastomer composition comprising:
The weight ratio (A) / (D) of (A) and (D) is 60/40 to 90/10,
Furthermore, a thermoplastic elastomer composition is provided in which the crosslinked phase (D) is dispersed as a dispersed phase having an average diameter of 50 μm or less in the continuous phase (A) (Claim 1).

  In this thermoplastic elastomer composition, since the crosslinked mixed composition (D) exists as a fine dispersed phase in the continuous phase of the thermoplastic polyester elastomer (A), the melt viscosity of the composition is continuous. A low value close to that of the thermoplastic polyester elastomer (A) alone forming the phase is exhibited. For this reason, deterioration of the appearance of the molded product can be suppressed, and a thin molded product such as an insulating tube can be manufactured by high-speed extrusion molding without causing variations in thickness and deterioration of the appearance.

  Here, the fine dispersed phase preferably has an average diameter of 50 μm or less, more preferably 10 μm or less, and particularly preferably 5 to 0.01 μm or less. If the average diameter is larger than the above range, the appearance of the molded product may be deteriorated.

  Furthermore, the thermoplastic elastomer composition of the present invention retains the excellent properties of the thermoplastic polyester elastomer. For example, it is possible to provide a molded product having lightness and excellent mechanical characteristics, heat resistance, and oil resistance. Moreover, the compounding | blending of a rubber component (mixed composition (D)) can give the molded article which is excellent also in a softness | flexibility. Therefore, by using the thermoplastic elastomer composition of the present invention, a lightweight tube having excellent mechanical properties, heat resistance, oil resistance, flexibility and appearance, and a coating with such excellent properties Can be provided by extrusion molding with high production efficiency.

  Here, the “thermoplastic polyester elastomer (A)” is a polyester block copolymer, and a crystalline high-melting hard segment (A-1) mainly composed of an aromatic polyester unit in the polymer main chain. ) (Hard segment) and a soft segment (A-2) (soft segment) having a low melting point mainly composed of an aliphatic polyether unit (a) and / or an aliphatic polyester unit (b).

  The aromatic polyester unit forming the hard segment (A-1) is a condensate of an acid component and a glycol component. As the acid component, substantially from terephthalic acid and / or 2,6-naphthalenedicarboxylic acid. The thing which becomes. However, in addition to these, a small amount of other aromatic dicarboxylic acids such as isophthalic acid or aliphatic dicarboxylic acids such as adipic acid, sebacic acid, cyclohexane-1,4-dicarboxylic acid, and dimer acid may be used in combination.

  Moreover, as a glycol component which forms an aromatic polyester unit, C2-C12 glycol, for example, ethylene glycol, propylene glycol, tetramethylene glycol, neopentyl glycol, hexanediol, decanediol, etc. are mentioned. In addition, although the minimum of melting | fusing point of a hard segment (A-1) is not specifically limited, Generally it is 150 degreeC or more, Preferably it is 170 degreeC or more.

  Examples of the aliphatic polyether unit (a) constituting the soft segment (A-2) include those formed of polyalkylene glycol having an average molecular weight in the range of about 400 to 600. Examples of the polyalkylene glycol include polyethylene glycol, polypropylene glycol, polytetramethylene glycol, polyethylene glycol-polypropylene glycol block copolymer, and the like. Polytetramethylene glycol is particularly preferable. A carbon number: oxygen ratio of 2 to 4.5 is preferably used. The aliphatic polyether unit (a) can be used not only as one type but also as a mixture of two or more types.

  The aliphatic polyester unit (b), which is another unit constituting the soft segment (A-2), can be obtained by polycondensation of an acid component mainly composed of an aliphatic dicarboxylic acid and a glycol component. It may be a homopolyester or a copolyester. Examples of the aliphatic dicarboxylic acid include succinic acid, adipic acid, sebacic acid, and decanedicarboxylic acid. As the acid component, in addition to these aliphatic dicarboxylic acids, a small amount of an aromatic dicarboxylic acid such as isophthalic acid may be used in combination.

  As a glycol component which forms the said aliphatic polyester unit (b), a C2-C12 glycol component can be mentioned, and it illustrated as a glycol component which forms the aromatic polyester unit of a hard segment (A-1). The thing similar to a thing can be used.

  The aliphatic polyester unit (b) may be a polylactone (for example, poly-ε-caprolactone) obtained by ring-opening polymerization of a cyclic lactone. The upper limit of the melting point of the aliphatic polyester unit (b) is not particularly limited, but is generally preferably 130 ° C. or lower, and particularly preferably 100 ° C. or lower.

  The composition ratio of the hard segment (A-1) and the soft segment (A-2) in the thermoplastic polyester elastomer (A) depends on the structural units of the hard segment and the soft segment, but is usually preferably a weight ratio. It is 95/5 to 5/95, and more preferably 70/30 to 30/70. When the composition ratio of the hard segment (A-1) is higher than the above range, the melting point of the thermoplastic polyester elastomer (A) is improved, and even the reaction temperature of the crosslinking agent used for dynamic crosslinking does not sufficiently melt and disperse. It becomes easy to become defective. On the other hand, when the composition ratio of the hard segment (A-1) is lower than the above range, the heat resistance tends to decrease. As the thermoplastic polyester elastomer (A), an elastomer having a softening point of 100 ° C. or higher is particularly suitable.

  The polyester block copolymer particularly preferably used as the thermoplastic polyester elastomer (A) uses polytetramethylene terephthalate or polytrimethylene terephthalate-2,6-naphthalate as the hard segment (A-1), and a soft segment (A- As 2), it is formed by using a polyether such as polytetramethylene glycol, an aliphatic polyester such as polytetramethylene adipate and poly-ε-caprolactone.

  As a part of the dicarboxylic acid or glycol, a polycarboxylic acid, a polyfunctional hydroxy compound, or a polyfunctional component such as oxyacid may be copolymerized. The polyfunctional component effectively acts as a viscosity-increasing component by copolymerizing in the range of 3 mol% or less. Examples of the polyfunctional component include trimellitic acid, trimesic acid, pyromellitic acid, benzophenone tetracarboxylic acid, butanetetracarboxylic acid, glycerin, pentaerythritol, or esters or acid anhydrides thereof.

  The “acrylic rubber (B)” is obtained by copolymerizing a monomer mixture containing at least one selected from an alkyl acrylate ester and an alkoxyalkyl acrylate ester and containing a crosslinkable monomer (B -1), and an olefin-acrylic acid alkyl ester copolymer rubber (B-2) containing a polymerized unit of a crosslinkable monomer. By including a polymerized unit of a crosslinkable monomer, a crosslinking active group can be introduced into the acrylic rubber (B), and the mixed composition (D) containing the acrylic rubber (B) can be crosslinked.

  Examples of the alkyl acrylate that can be used in the production of (B-1) include methyl acrylate, ethyl acrylate, acrylic acid-n-propyl, isopropyl acrylate, acrylic acid-n-butyl, acrylic acid isobutyl, acrylic acid- tert-butyl, acrylate-n-pentyl, acrylate-n-hexyl, acrylate-n-heptyl, acrylate-n-octyl, acrylate-2-ethylhexyl, nonyl acrylate, decyl acrylate, dodecyl acrylate Etc. Among these, an alkyl acrylate ester having 2 to 4 carbon atoms in the alkyl group is preferable in that it can exhibit excellent flexibility and oil resistance.

  Examples of the alkoxyalkyl acrylates that can be used for the production of (B-1) include alkoxyalkyl acrylates having 2 to 4 carbon atoms in the alkyl group, such as 2-methoxyethyl acrylate and 2-ethoxyethyl acrylate And 2-butoxyethyl acrylate. Among these, 2-methoxyethyl acrylate is preferable because it can exhibit excellent oil resistance. For the production of (B-1), one or more of the above exemplified monomers can be appropriately selected and used.

  In the production of (B-1), the above-exemplified monomers are used as main components, and a crosslinkable monomer is further used. In addition to these, physical properties such as oil resistance, molding processability and flexibility. Methacrylic acid alkyl esters such as methyl methacrylate and ethyl methacrylate; methacrylic acid alkoxyalkyl esters such as methacrylic acid-2-methoxyethyl and methacrylic acid-2-ethoxyethyl; (meth) acrylic acid-2 -Hydroxyl group-containing monomers such as hydroxyethyl and (meth) acrylic acid-2-hydroxypropyl; active chlorine-containing monomers such as 2-chloroethyl vinyl ether, vinyl monochloroacetate and allyl chloroacetate; (meth) acrylic acid Fluorine such as trifluoromethylmethyl and (meth) acrylic acid-2-trifluoromethylethyl (Meth) acrylic acid esters; aromatic vinyl compounds such as styrene and α-methylstyrene; vinyl nitriles such as acrylonitrile and methacrylonitrile; vinylamides such as acrylamide, methacrylamide and N-methylolacrylamide; ethylene, propylene, isobutene and the like α-olefins; conjugated dienes such as butadiene, isoprene and chloroprene; bifunctional (meth) acrylates, trifunctional (meth) acrylates and copolymerizable monomers such as vinyl acetate and vinyl chloride It can also be used and copolymerized within the range not impairing the gist of the invention.

  The copolymerization amount of these copolymerizable monomers is preferably 40% by mass or less, and more preferably 30% by mass or less. When this copolymerization amount exceeds 40 mass%, the balance of physical properties, such as a softness | flexibility of a rubber | gum rubber (B-1), oil resistance, a low temperature characteristic, and moldability, may be impaired.

  As the crosslinkable monomer used in the production of (B-1) and (B-2), the reaction of the carboxyl group-containing monomer with the crosslinking agent used in dynamic crosslinking proceeds relatively quickly. ,preferable. By using a carboxyl group-containing monomer as the crosslinkable monomer, a thermoplastic elastomer composition (Claim 2) in which the acrylic rubber (B) is an acrylic rubber containing a carboxyl group in the molecule can be obtained.

  Examples of the carboxyl group-containing monomer include (meth) acrylic acid, crotonic acid, maleic acid and the like. Further, the ratio of the polymerized units of the crosslinkable monomer in (B-1) or (B-2) is preferably in the range of 0.5 to 15% by mass. If it is less than 0.5%, the mixed composition (D) may not be sufficiently crosslinked. On the other hand, when it exceeds 15%, the mixture composition (D) is excessively cross-linked, so that good moldability of the thermoplastic elastomer composition may not be obtained.

  On the other hand, (B-2) olefin-acrylic acid ester copolymer rubber is an olefin constituting (B-2) which can be obtained by copolymerizing an olefin, an acrylic acid ester and a crosslinkable monomer by a known method. Can include ethylene, propylene, butene-1, isobutylene, pentene, heptene, octene, and the like. Among these, C1-C4 α-olefins are preferable, and ethylene is particularly preferable. It may be a mixture of two or more olefins.

  A thermoplastic elastomer composition in which the acrylic rubber (B) is an ethylene acrylic rubber containing a carboxyl group in the molecule by using a carboxyl group-containing monomer as the crosslinkable monomer and using ethylene that is particularly preferable as the olefin (claim) Item 3) can be obtained.

  Examples of the alkyl acrylate ester constituting (B-2) include methyl acrylate, ethyl acrylate, t-butyl acrylate, n-butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, and the like C1 -C12 alkyl (meth) acrylate can be mentioned, Among these, C1-C4 alkyl (meth) acrylate is preferable, and methyl acrylate is particularly preferable.

  As a ratio of crosslinkable monomers such as olefin, acrylic acid alkyl ester, and carboxyl group-containing monomer in (B-2), olefin 30 to 89.5 mass%, acrylic acid alkyl ester 69.5 to 10 The mass% and the crosslinkable monomer 0.5-15 mass% are preferable. More preferably, the olefin is 30 to 80% by mass, the acrylic acid ester is 69.5 to 10% by mass, the crosslinkable monomer is 0.5 to 10% by mass, and the olefin is 35 to 80% by mass, and the acrylic acid ester is 64 to 19%. The mass% is 1 to 8 mass% of the crosslinkable monomer.

  The acrylic oligomer (C) mixed with the acrylic rubber (B) to constitute the mixed composition (D) is an alkyl acrylate such as methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, octyl acrylate, or the like. And an acrylic methacrylate (or alkyl methacrylate) polymer (oligomer) obtained by copolymerizing a monomer having a main component monomer and an alkyl methacrylate and a monomer having a double bond group such as an acryloyl group or a methacryloyl group. And having two or more double-bonding functional groups for bonding (crosslinking) with the acrylic rubber (B) in the molecule. The double bond functional group is present in a pendant form (for example, a compound represented by the following formula (1)) or at both ends (for example, represented by the following formula (2). Any of (compounds) can be preferably used.

（式中、Ｒはアルキル基を表し、Ｒ’はＨ又はアルキル基を表す。）

(In the formula, R represents an alkyl group, and R ′ represents H or an alkyl group.)

  The acrylic oligomer (C) preferably has a viscosity at 25 ° C. of 900 to 50000 mPa · s, more preferably 1000 to 20000 mPa · s. If the viscosity of the acrylic oligomer (C) is too low, bleeding from the molded product is likely to occur, causing stickiness and the like. On the other hand, if the viscosity of the acrylic oligomer (C) is too high, the effect of finely dispersing the acrylic rubber (B) is reduced, and the appearance of the molded product tends to be poor.

  In the thermoplastic elastomer composition of the present invention, the mixed composition (D) containing the acrylic rubber (B) is finely dispersed and crosslinked. Crosslinking improves elasticity and further improves heat resistance and oil resistance. Crosslinking is preferably performed by dynamic crosslinking.

  The thermoplastic elastomer composition of the present invention preferably contains a crosslinking agent for acrylic rubber in order to crosslink the mixed composition (D). As the crosslinking agent for acrylic rubber, various crosslinking agents suitable for it can be used depending on the type of crosslinking active group introduced into the molecule of acrylic rubber. For example, examples of the crosslinking agent that can be suitably used when the crosslinking active group is an epoxy group include ammonium benzoate and the like, and if necessary, a crosslinking accelerator such as a guanidine compound such as di-o-tolylguanidine is used. be able to. Examples of the crosslinking agent that can be suitably used when the crosslinking active group is a carboxyl group include epoxy compounds such as hexamethylenediamine carbamate and diglycidyl ether, and 2,2 ′-(1,3-phenylene) bis- Bisoxazoline compounds such as 2-oxazoline (PBO) are exemplified.

  When cross-linking of the mixed composition (D) is performed by dynamic cross-linking, in particular, a combination of a carboxyl group as a cross-linking active group and a bisoxazoline compound as a cross-linking agent serves as a reaction temperature and a matrix for the cross-linking reaction. Since the melting temperature of the thermoplastic polyester elastomer is well balanced, the control and operation of the crosslinking process is facilitated, which is preferable. In addition, in consideration of crosslinking the acrylic rubber without excess or deficiency, the addition amount of the crosslinking agent should be adjusted so that the theoretical equivalent of the functional group of the crosslinking agent and the theoretical equivalent of the crosslinking active group of the acrylic rubber are almost the same. It is preferable to adjust.

  The ratio of the thermoplastic polyester elastomer (A) and the mixed composition (D) constituting the thermoplastic elastomer composition of the present invention is (A) / (D) = 60/40 to 90/10 in weight ratio. is there. When the proportion of the mixed composition (D) is smaller than this range, sufficient flexibility is not imparted to a molded article produced from the composition. As a result, in the case of covering the wires / cables, there is a problem that, when a plurality of wires / cables are bundled to form a harness, handling in a narrow place becomes difficult.

  On the other hand, when the proportion of the mixed composition (D) is larger than this range, thermoplasticity in which the mixed composition (D) is finely and uniformly dispersed in the continuous phase composed of the thermoplastic polyester elastomer (A). It becomes difficult to obtain an elastomer composition, the extrusion moldability is reduced, and problems such as irregularities appearing on the surface of a molded product produced from the composition and poor appearance are likely to occur.

  For example, when cross-linking is performed by dynamic cross-linking, the mixed composition (D) (acrylic rubber component) present in a large amount in the mixture is fused when phase-separating from the thermoplastic polyester elastomer (A) by cross-linking. The dispersed particle size of the dispersed phase increases, or a large continuous phase equivalent to the continuous phase of the thermoplastic polyester elastomer (A) is produced. Even when the mixed composition (D) is crosslinked and then dispersed in the continuous phase comprising the thermoplastic polyester elastomer (A) to obtain a thermoplastic elastomer composition, the thermoplastic polyester elastomer (A) constituting the continuous phase is also obtained. Since the amount of is relatively insufficient, aggregation of the dispersed phase tends to occur.

  Therefore, in any case, the fine dispersed phase composed of the crosslinked product of the mixed composition (D) is uniformly dispersed in the continuous phase composed of the thermoplastic polyester elastomer (A) without causing aggregation or the like. It is difficult to obtain a thermoplastic elastomer composition having a different structure. As a result, the extrudability of the resin composition is lowered, and for example, it becomes difficult to produce a thin molded product having a good appearance with a thickness of about 0.3 to 1.0 mm by extrusion molding at high speed.

  Furthermore, since the crosslinked rubber phase becomes coarse, there is also a problem that the wear resistance of the thin molded product is greatly reduced. When the dispersed particle size of the cross-linked product of the mixed composition (D) is large, or when the mixed composition (D) produces a large continuous phase equivalent to the continuous phase of the thermoplastic polyester elastomer (A), Since the volume resistivity of the molded product is lowered, there may be a case where sufficient insulation suitable for each application described above cannot be imparted to the thin molded product.

  Therefore, in order to prevent the above problems, the ratio of the thermoplastic polyester elastomer (A) and the mixed composition (D) should be in the range of (A) / (D) = 60/40 to 90/10 in weight ratio. There is.

  In the invention according to claim 4, the weight ratio (B) / (C) of the acrylic rubber (B) and the acrylic oligomer (C) constituting the mixed composition (D) is 96/4 to 80/20. The thermoplastic elastomer composition according to any one of claims 1 to 3, wherein the composition is a thermoplastic elastomer composition. It is.

  When (B) / (C) is larger than 96/4, the extrusion moldability is deteriorated and the appearance of the molded product tends to be poor, and a tube, electric wire or cable having a good appearance can be obtained by high-speed extrusion. It tends to be difficult to obtain. On the other hand, when (B) / (C) is smaller than 80/20, the component (C) tends to remain in the molded product, and bleeding of the component (C) from the molded product tends to occur.

  The thermoplastic elastomer composition of the present invention comprises a thermoplastic polyester elastomer (A), a mixed composition (D) composed of acrylic rubber (B) and acrylic oligomer (C), and further mixed composition (D). It can be produced by crosslinking. Mixing of the thermoplastic polyester elastomer (A) and the mixed composition (D) is performed after the acrylic rubber (B) and the acrylic oligomer (C) are mixed to produce the mixed composition (D). A composition in which the mixed composition (D) is dispersed in a fine and uniform phase is obtained by mixing the acrylic rubber (B) and the acrylic oligomer (C) in advance and then mixing with the thermoplastic polyester elastomer (A). It is done. Further, as the crosslinking of the mixed composition (D), dynamic crosslinking using a crosslinking agent for acrylic rubber is preferable.

Invention of Claim 5 corresponds to the said preferable aspect of the manufacturing method of the thermoplastic-elastomer composition of this invention,
A mixed composition (D) comprising the thermoplastic polyester elastomer (A) and the acrylic rubber (B) and the acrylic oligomer (C) having two or more double bond groups in the molecule, (A) / (D) = A method for producing a thermoplastic elastomer composition containing a weight ratio of 60/40 to 90/10, comprising:
A first step of producing a mixed composition (D) by mixing the acrylic rubber (B) and the acrylic oligomer (C);
A second step of dynamically crosslinking the mixed composition (D) while mixing the thermoplastic polyester elastomer (A), the mixed composition (D) produced in the first step and the crosslinking agent for acrylic rubber; The present invention provides a method for producing a thermoplastic elastomer composition characterized by comprising:

  The mixing in the first step is carried out by kneading the above components with an open roll mixer, a Banbury mixer, a pressure kneader, a single-screw or multi-screw extruder type mixer, or a combination thereof. . From the viewpoint of productivity, a method using a twin screw extruder is preferable as a continuous production method.

  In addition, the dynamic crosslinking referred to here means that the mixed composition (D) is advanced while mixing (kneading) the thermoplastic polyester elastomer (A) and the mixed composition (D) together with a crosslinking agent for acrylic rubber. And a cross-linking method in which a cross-linked product is finely dispersed. In the method in which the mixed composition (D) is crosslinked and then dispersed in (A), the amount of the thermoplastic polyester elastomer (A) constituting the continuous phase is relatively insufficient, so that the mixed composition (D) is dispersed. Phase aggregation tends to occur, but in the case of dynamic crosslinking, a composition in which crosslinked (D) is dispersed in a fine and uniform phase is obtained.

  The mixing in the second step is performed by an open roll mixer, a Banbury mixer, a pressure kneader, a single-screw or multi-screw extruder type mixer, or a combination of these in the same manner as the mixing in the first step. Of these, the method using a twin screw extruder is preferred.

  The twin screw extruder used at this time is preferably one with L / D = 30 or more. The method of adding each component at the time of dissolution kneading is any of (A) and (D) the method of adding both components and a crosslinking agent at the same time, and the method of adding the crosslinking agent halfway after kneading both components. However, a method of adding a crosslinking agent after kneading both components (A) and (D) is preferable from the viewpoint of the dispersibility of the crosslinked rubber. In this case, a plasticizer and a crosslinking agent are added from the middle of the extruder.

  The thermoplastic elastomer composition of the present invention produced as described above is an insulating tube used for coating of electric wires / cables, bundling of electric wires / cables, protection of electric wires / cable ends, etc. by extrusion molding or the like. , Processed into thin-walled molded products such as heat-shrinkable tubes. Extrusion molding is performed by mixing into the mold after the mixing in the second step, but the thermoplastic elastomer composition of the present invention has good extrudability, for example, about 0.3 to 1.0 mm. Even a thin-walled molded product having a small thickness can be easily manufactured by extrusion molding at a high speed, and a product having a uniform thickness and a good appearance can be efficiently manufactured. In addition, this product satisfies high heat resistance and oil resistance, and is compatible with flexibility, so it is suitable for use as thin-walled molded products such as wire / cable coatings, insulation tubes, and heat-shrinkable tubes. .

  Here, as the coating of the electric wire / cable, the surface of the conductor is directly coated to insulate the conductor, or the sheath (protective layer) covering the outer side of the insulated single-core or multi-core conductor. Etc. Among these, the insulating coating can be formed by coating the outer circumference of the thermoplastic elastomer composition of the present invention while continuously extruding the conductor while feeding the conductor at a constant speed. .

  After coating, when the thermoplastic polyester elastomer (A) in the thermoplastic elastomer composition is crosslinked, higher heat resistance and oil resistance can be imparted. Therefore, preferably, after coating, the thermoplastic polyester elastomer (A) is crosslinked. Is done. As a crosslinking method, a method of irradiating ionizing radiation such as an accelerated electron beam or gamma ray is preferable, and a method of irradiating an electron beam is particularly preferable because of its easy control.

  According to a sixth aspect of the present invention, a preferred embodiment of the production method, that is, after the second step, the mixture of the thermoplastic polyester elastomer (A), the mixed composition (D) and the acrylic rubber crosslinking agent is further subjected to ionizing radiation. It has the process of irradiating, The manufacturing method of the thermoplastic-elastomer composition of Claim 5 characterized by the above-mentioned is provided.

  Furthermore, the present invention provides, as a seventh aspect, the above-described preferable electric wire or cable, that is, a coating made of the thermoplastic elastomer composition according to any one of the first to fourth aspects, and is irradiated with ionizing radiation. An electric wire or cable is provided.

As the conductor, a soft copper twisted conductor having a cross-sectional area of about 0.35 to 1.0 mm ² is generally used from the viewpoint of allowable current value, tensile strength, vibration resistance, and the like. Moreover, the thickness of the insulation coating for covering the twisted conductor is about 0.3 to 1.0 mm. The sheath is formed in the same manner.

  The invention according to claim 8 is a tube obtained by molding the thermoplastic elastomer composition according to any one of claims 1 to 4 into a tube shape and irradiating with ionizing radiation. Yes, it can be used as an insulating tube.

  This tube can be formed by continuously extruding the thermoplastic elastomer composition of the present invention into a tube shape using an extruder. Since high heat resistance and oil resistance can be imparted by crosslinking the thermoplastic polyester elastomer (A) in the thermoplastic elastomer composition after coating, irradiation with ionizing radiation such as accelerated electron beams and gamma rays is preferable. Etc., the crosslinking of (A) is performed. In particular, a method of irradiating with an electron beam is preferable from the viewpoint of easy control. The thickness of the tube is about 0.3 to 1.0 mm.

  Since this tube is formed from the thermoplastic elastomer composition of the present invention, it has excellent mechanical properties, heat resistance, oil resistance, excellent flexibility and therefore flexibility, and good appearance. And is suitably used as an insulating tube.

  The invention according to claim 9 is the tube according to claim 8, which is further expanded in the radial direction to impart heat shrinkability.

  A heat-shrinkable tube, after forming the tube according to claim 8, rapidly heats the tube in a radially expanded state while being heated and softened to impart heat-shrinkability to the insulating tube. Manufactured by. Conditions and methods for expanding the tube in the radial direction, cooling conditions, and the like can be performed under the same conditions as in the manufacture of known heat-shrinkable tubes.

  Since the thermoplastic elastomer composition of the present invention is excellent in extrusion moldability, it can be molded by extrusion molding with high production efficiency, etc., and has excellent mechanical properties, heat resistance, oil resistance and flexibility. A thin-walled molded article having a good appearance can be obtained. A thermoplastic elastomer composition having such excellent properties can be easily produced by the method for producing a thermoplastic elastomer composition of the present invention. In addition, since the thermoplastic elastomer composition of the present invention has the above-mentioned excellent properties, it is obtained by crosslinking with the electric wire, cable or tube of the present invention obtained using this composition as a raw material, particularly by irradiation with ionizing radiation. Wires or cables and tubes to be produced are excellent in mechanical properties, heat resistance, oil resistance and flexibility, and have a good appearance, covering the wires and cables that make up the electronic control wire harness in automobiles, aircraft, etc. It is suitably used for bundling electric wires and cables, protecting electric wires and cable ends, and the like.

  Hereinafter, embodiments of the present invention will be described by way of examples. In addition, this invention is not limited to a following example. Various changes can be made without departing from the spirit of the present invention.

(Materials used for manufacturing thermoplastic elastomer composition)
The following materials were used as materials for producing the thermoplastic elastomer compositions of Examples and Comparative Examples.
Polyester elastomer ((A) in claim 1): Hytrel 4056 (manufactured by DuPont)
Ethylene acrylic rubber (AEM) ((B) in claim 1): Baymac GLS (manufactured by DuPont)
Acrylic oligomer ((C) in claim 1): EBECRYL745 (manufactured by Daicel Cytec)
・ Filler: Carbon black ・ Crosslinking aid: Triacyl cyanurate (TAIC, Nippon Kasei Co., Ltd.)
Antioxidant: 4,4′-bis (α, α′-dimethylbenzyl) diphenylamine Hydrolysis inhibitor: polycarbodiimide (reagent)
・ Crosslinking agent: 1,3-phenylenebisoxazoline (1,3-PBO) (reagent)

(Method for producing thermoplastic elastomer composition)
First, ethylene acrylic rubber (AEM) and a predetermined amount (described in Table 1) of an acrylic oligomer were mixed in advance with an open roll. The mixing temperature was 100-120 ° C., and the mixing time was 5 minutes.

  A mixed composition obtained by the mixing ((D) in claim 1) and a predetermined amount of other raw materials excluding the crosslinking agent (described in Table 1) are charged into a pressure kneader for 5 to 10 minutes. After mixing at 100 to 170 ° C., a crosslinking agent was added and mixed at 200 ° C. for 10 minutes, and finally a hydrolysis inhibitor was added and kneaded. After adjusting the shape of the obtained mixture to form a pellet, it was continuously extruded into a tube shape with a single screw extruder. The single screw extruder used was a cylinder diameter: 30 mmφ, L / D = 24, C / R = 2.6, screw shape: full flight. The set temperature of the extruder was 1800C for the supply unit, 200C for the compression unit, 200C for the weighing unit, and 220C for the head and die. The extrusion linear velocity was 20 m / min.

  After extrusion molding into a tube shape, an accelerated electron beam with an acceleration voltage of 1 MeV was irradiated so that the irradiation dose was 150 kGy to crosslink the thermoplastic polyester elastomer to obtain an insulating tube. The design shape of the insulating tube was set to an inner diameter of 2.1 mmφ and a thickness of 0.75 mm.

  The insulating tube thus obtained was observed for the surface state, and the surface state was slightly exaggerated when it was “extruded appearance defect”, and when the surface was smooth, “extruded appearance was good” The results are shown in the column of “Extrudability” in Table 1. The presence or absence of bleed was also observed visually and the results are shown in Table 1.

なお、表１中のＰＥ（Ａ）はポリエステルエラストマーを、ＡＥＭ（Ｂ）はエチレンアクリルゴムを、ＡＣ（Ｃ）はアクリルオリゴマーを、ＣＢはカーボンブラックを示す。

In Table 1, PE (A) indicates a polyester elastomer, AEM (B) indicates an ethylene acrylic rubber, AC (C) indicates an acrylic oligomer, and CB indicates carbon black.

  As shown in Table 1, the tubes of the examples all had a good appearance after extrusion, and no bleed was observed. On the other hand, Comparative Example 1 had a poor appearance, and bleeding was also observed. Further, in Comparative Example 2, the acrylic oligomer was too much and oozed out during extrusion, so that the screw could not be continuously extruded. That is, in Comparative Example 2, extrusion itself was unstable, and it was difficult to produce a tube having a firm shape.

Claims (9)

Heat obtained by mixing a thermoplastic polyester elastomer (A) and an acrylic rubber (B) and a mixed composition (D) comprising an acrylic oligomer (C) having two or more double bond groups in the molecule. A plastic elastomer composition comprising:
The weight ratio (A) / (D) of (A) and (D) is 60/40 to 90/10,
Furthermore, the thermoplastic elastomer composition, wherein the crosslinked phase (D) is dispersed as a dispersed phase having an average diameter of 50 μm or less in the continuous phase (A).   The thermoplastic elastomer composition according to claim 1, wherein the acrylic rubber (B) is an acrylic rubber containing a carboxyl group in the molecule.   The thermoplastic elastomer composition according to claim 2, wherein the acrylic rubber (B) is an ethylene acrylic rubber containing a carboxyl group in the molecule.   The weight ratio (B) / (C) of the acrylic rubber (B) and the acrylic oligomer (C) constituting the mixed composition (D) is 96/4 to 80/20. The thermoplastic elastomer composition according to any one of claims 1 to 3. A mixed composition (D) comprising the thermoplastic polyester elastomer (A) and the acrylic rubber (B) and the acrylic oligomer (C) having two or more double bond groups in the molecule, (A) / (D) = A method for producing a thermoplastic elastomer composition containing a weight ratio of 60/40 to 90/10, comprising:
A first step of producing a mixed composition (D) by mixing the acrylic rubber (B) and the acrylic oligomer (C);
A second step of dynamically crosslinking the mixed composition (D) while mixing the thermoplastic polyester elastomer (A), the mixed composition (D) produced in the first step, and the crosslinking agent for acrylic rubber; A method for producing a thermoplastic elastomer composition.   The heat according to claim 5, further comprising a step of irradiating the mixture of the thermoplastic polyester elastomer (A), the mixture composition (D) and the crosslinking agent for acrylic rubber with ionizing radiation after the second step. A method for producing a plastic elastomer composition.   An electric wire or cable having a coating made of the thermoplastic elastomer composition according to any one of claims 1 to 4 and being irradiated with ionizing radiation.   A tube obtained by molding the thermoplastic elastomer composition according to any one of claims 1 to 4 into a tube shape and irradiating with ionizing radiation.   The tube according to claim 8, further expanded in the radial direction and imparted with heat shrinkability.