JP5097561B2 - High heat aging thermoplastic elastomer composition - Google Patents

Description

  The present invention relates to a thermoplastic elastomer composition, and more particularly to a thermoplastic elastomer composition that can provide a molded article having excellent heat aging resistance.

  Conventionally, soft vinyl chloride resin has been the mainstream for interior skin materials such as instrument panels and door trims for automobiles, but in recent years, olefinic thermoplastic elastomers have begun to be used from the viewpoint of reducing the weight of materials.

  In the case of a passenger car, the temperature inside the closed car becomes quite hot especially in the hot weather in summer, but recently, the windshield etc. tends to be larger in the design of a passenger car. As the temperature rises, higher heat aging resistance has been demanded.

  In order to improve the heat aging resistance, a heat stabilizer (antioxidant) is usually blended, but depending on the blending amount, the heat stabilizer may come out from the inside and damage the appearance, so-called “bleed out” Is a problem.

  The present invention solves the problems associated with the prior art as described above, and a first object of the present invention is to provide a thermoplastic elastomer composition capable of giving a molded article excellent in heat aging resistance. It is to provide. The second object of the present invention is to provide a thermoplastic elastomer composition in which the bleed-out phenomenon is suppressed.

The present invention includes the following inventions.
(1) 10 to 60 parts by weight of polyolefin (A), 30 to 87 parts by weight of crosslinked rubber (B) and 3 to 50 parts by weight of softener (C) [provided that (A), (B) and (C) The total amount is 100 parts by weight] and phenolic heat stabilizer (D) 0.02 to 0.3 parts by weight, and the elongation at break after aging in an air oven at 130 ° C. for 500 hours is A thermoplastic elastomer composition that retains 80% or more of the value.
(2) The thermoplastic elastomer composition according to (1), wherein the softening agent (C) is a paraffinic mineral oil.
(3) The thermoplastic elastomer composition according to (1) or (2), wherein the softening agent (C) has an aniline point of 140 ° C. or lower and a sulfur content of 20 ppm or higher.
(4) The thermoplastic elastomer composition according to any one of (1) to (3), wherein the softening agent (C) has a kinematic viscosity at 40 ° C. of 150 to 1000 centistokes.
(5) The thermoplastic elastomer composition according to any one of (1) to (4), further comprising 0.02 to 0.3 parts by weight of a heat-resistant stabilizer other than phenol.
(6) The thermoplastic elastomer composition as described in (5) above, wherein the heat-resistant stabilizer other than phenol-based is a sulfur-based heat-resistant stabilizer.
(7) The above (1) to (6) produced by dynamically heat-treating at least all of the crosslinked rubber (B) and part or all of the polyolefin (A) in the presence of a crosslinking agent. The thermoplastic elastomer composition according to any one of the above.
(8) The crosslinked rubber (B) is an ethylene / α-olefin / non-conjugated polyene copolymer rubber, ethylene / α-olefin copolymer rubber, isoprene rubber or hydrogenated product thereof, butadiene rubber or hydrogenated product thereof. , Styrene / butadiene rubber or hydrogenated product thereof, styrene / isoprene rubber or hydrogenated product thereof, chloroprene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile / butadiene rubber, chlorinated polyethylene rubber, fluorine rubber, silicone rubber, polysulfide rubber And the thermoplastic elastomer composition according to any one of (1) to (7), which is at least one rubber selected from the group consisting of urethane rubber.
(9) Any of the above (1) to (8), wherein the polyolefin (A) is a propylene-based polymer resin, and the crosslinked rubber (B) is an ethylene / α-olefin / non-conjugated polyene copolymer rubber A thermoplastic elastomer composition according to claim 1.
(10) The thermoplastic elastomer composition according to any one of (1) to (9), wherein the rubber is crosslinked with an organic peroxide.
(11) The thermoplastic elastomer composition according to any one of (1) to (10), which is produced using a twin-screw extruder.
(12) 10 to 60 parts by weight of polyolefin (A), 30 to 87 parts by weight of rubber (B ′) and 3 to 50 parts by weight of softening agent (C) (provided that (A), (B ′) and (C) are total) The amount is 100 parts by weight] and the phenol-based heat stabilizer (D) 0.02 to 0.3 parts by weight is dynamically heat-treated in the presence of a crosslinking agent.

  By using the thermoplastic elastomer composition of the present invention, a molded article having excellent heat aging resistance can be provided.

Hereinafter, the thermoplastic elastomer composition of the present invention will be specifically described.
The thermoplastic elastomer composition of the present invention comprises a polyolefin (olefin resin) (A), a crosslinked rubber (B), a softening agent (C), a phenolic heat stabilizer (D), and optionally a phenolic resin. A heat-resistant stabilizer (E) other than the above, for example, a composition comprising a sulfur-based heat-resistant stabilizer.

Polyolefin (olefin resin) (A)
The polyolefin (olefin resin) (A) used in the present invention is usually composed of a high molecular weight solid product obtained by polymerizing one or more monoolefins by a high pressure method or a low pressure method. Examples of such a resin include isotactic and syndiotactic monoolefin polymer resins. These representative resins are commercially available.

  The suitable raw material olefin of the polyolefin (A) is preferably an α-olefin having 2 to 20 carbon atoms, specifically, ethylene, propylene, 1-butene, 1-pentene, 1-hexene, 1-octene, Examples include 1-decene, 2-methyl-1-propene, 3-methyl-1-pentene, 4-methyl-1-pentene, 5-methyl-1-hexene and the like. These olefins are used alone or in combination of two or more.

The polymerization mode may be random type or block type as long as a resinous material is obtained.
These polyolefins may be used alone or in combination of two or more.

  Among these polyolefins, propylene-based polymers, specifically, propylene homopolymer, propylene / ethylene block copolymer, propylene / ethylene random copolymer, propylene / ethylene / butene random copolymer, and the like are particularly preferable.

  The polyolefin (A) used in the present invention has an MFR (ASTM D1238-65T, 230 ° C., 2.16 kg) usually in the range of 0.01 to 100 g / 10 minutes, particularly 0.05 to 50 g / 10 minutes. Is preferred.

  The polyolefin (A) has a role of improving the fluidity and heat resistance of the composition.

  In the present invention, the polyolefin (A) is 10 to 60 parts by weight, preferably 15 to 50 parts by weight based on 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softening agent (C). Used in parts by weight. When the polyolefin (A) is used in such a proportion, a thermoplastic elastomer composition having excellent flexibility and rubber elasticity and excellent molding processability can be obtained.

Cross-linked rubber (B)
As the crosslinked rubber (B) used in the present invention, usually, ethylene / α-olefin / non-conjugated polyene copolymer rubber, ethylene / α-olefin copolymer rubber, isoprene rubber or hydrogenated product thereof, butadiene Rubber or hydrogenated products thereof, styrene / butadiene rubber or hydrogenated products thereof, styrene / isoprene rubber or hydrogenated products thereof, chloroprene rubber, butyl rubber, halogenated butyl rubber, acrylonitrile / butadiene rubber, chlorinated polyethylene rubber, fluorine rubber, silicone At least one rubber selected from the group consisting of rubber, polysulfide rubber and urethane rubber is used. Here, the “hydrogenated product” refers to a product in which all or part of the double bond is saturated by hydrogenation treatment.

Among these, ethylene / α-olefin / nonconjugated polyene copolymer rubber is preferable, and ethylene / propylene / nonconjugated diene rubber having the following physical properties is particularly preferable.
Ethylene / propylene ratio: 50/50 to 90/10 (molar ratio)
Iodine number: 3-30 (g / 100g)
Mooney viscosity ML _{1 + 4} (100 ° C.): 15 to 250

  Specific examples of the nonconjugated diene used in the ethylene / propylene / nonconjugated diene rubber include dicyclopentadiene, cyclooctadiene, methylenenorbornene (for example, 5-methylene-2-norbornene), and ethylidenenorbornene (for example, 5 -Ethylidene-2-norbornene), cyclic dienes such as methyltetrahydroindene, 5-vinyl-2-norbornene, 5-isopropylidene-2-norbornene, 6-chloromethyl-5-isopropenyl-2-norbornene, norbornadiene; 1 , 4-Hexadiene, 3-methyl-1,4-hexadiene, 4-methyl-1,4-hexadiene, 5-methyl-1,4-hexadiene, 4,5-dimethyl-1,4-hexadiene, 6-methyl -1,6-octadiene, 7-methyl-1,6- Ttadiene, 6-ethyl-1,6-octadiene, 6-propyl-1,6-octadiene, 6-butyl-1,6-octadiene, 6-methyl-1,6-nonadiene, 7-methyl-1,6- Nonadiene, 6-ethyl-1,6-nonadiene, 7-ethyl-1,6-nonadiene, 6-methyl-1,6-decadiene, 7-methyl-1,6-decadiene, 6-methyl-1,6- Examples thereof include chain dienes such as undecadiene and 7-methyl-1,6-octadiene.

  In the present invention, the crosslinked rubber (B) is 30 to 87 parts by weight, preferably 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softening agent (C), Used in a proportion of 35 to 70 parts by weight.

Softener (C)
As the softener (C) used in the present invention, a softener usually used for rubber can be used. Specifically, petroleum-based softeners such as process oil, lubricating oil, paraffin oil, liquid paraffin, petroleum asphalt, and petroleum jelly; coal-tar softeners such as coal tar and coal tar pitch; castor oil, linseed oil, rapeseed oil Fat oils such as soybean oil and coconut oil; tall oils; waxes such as beeswax, carnauba wax and lanolin; fatty acids such as ricinoleic acid, palmitic acid, stearic acid, barium stearate, calcium stearate, zinc laurate or metals thereof Salts: Synthetic polymer materials such as terpene resin, petroleum resin, coumarone indene resin, atactic polypropylene; ester softeners such as dioctyl phthalate, dioctyl adipate, dioctyl sebacate; microcrystalline wax, sub (factis), liquid polybutadiene , Modified liquid poly Tajien, liquid Thiokol, and the like.

  Of these softeners, hydrocarbon softeners are preferred, mineral oils such as paraffinic mineral oils, naphthenic mineral oils and aromatic mineral oils are more preferred, and paraffinic mineral oils are most preferred.

  Paraffinic mineral oil is a paraffinic process oil generally used as a rubber softener, and is a paraffinic lubricating fraction obtained by refining mineral oil.

  The paraffinic mineral oil preferably used in the present invention has a% CP in ring analysis of 50 or more, more preferably 60 to 80, and a total acid value of 0.05 (mgKOH / g) or less, more preferably 0.01 or less. Suitable are those having an aniline point of 100 to 160 ° C., more preferably 120 to 150 ° C. and a kinematic viscosity at 40 ° C. of 150 to 1000 centistokes, more preferably 200 to 500 centistokes.

  In addition, when a paraffinic mineral oil having an aniline point of 140 ° C. or lower and a sulfur content of 20 ppm or higher is used as the softener (C), the occurrence of a bleed-out phenomenon is particularly suppressed. From the viewpoint of suppressing the bleed-out phenomenon, the aniline point is preferably 100 to 140 ° C, more preferably 120 to 140 ° C, and the sulfur content is preferably 20 to 10,000 ppm, more preferably 100 to 5,000 ppm. It is. Suppression of such a bleed-out phenomenon is recognized because the softening agent satisfying the above parameters has a high affinity with a phenol compound that is a polar substance used as the phenol heat resistance stabilizer (D), and the phenol It is considered that the heat stabilizer is strongly fixed in the elastomer composition.

  Further, when a heat-resistant stabilizer other than phenolic is a polar substance, the bleed-out phenomenon of these heat-resistant stabilizers other than phenolic will be suppressed by the same mechanism.

  Naphthenic mineral oil refers to those having a% CP in ring analysis of 50 or less and% CN of about 35 or more, and aromatic mineral oils having% CP of 50 or less and% CA of about 35 or more. Say things.

  In the present invention, the softener (C) is 3 to 50 parts by weight, preferably 10 to 10 parts by weight with respect to 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softener (C). Used in a proportion of 40 parts by weight.

  In the present invention, the softening agent (C) may be added during the production of the thermoplastic elastomer, or may be previously oil-extended on the raw rubber.

  In addition, the value of the aniline point of the softening agent (C) in this specification shows the value measured by the test tube method prescribed | regulated to JISK2256, and the value of sulfur content is the microcoulometric titration oxidation method prescribed | regulated to JISK2541. The value measured in.

Phenolic heat stabilizer (D)
The phenol-based heat stabilizer (D) used in the present invention is an organic compound having a phenol structure in the molecule and has a radical scavenging function. Specific examples of the phenol-based heat stabilizer (D) used in the present invention include 2-tert-butyl-4-methoxyphenol, 2-tert-butyl-4,6-dimethoxyphenol, and 3,5-dithiol. -Tert-butyl-4-hydroxytoluene, 4-hydroxymethyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol, 2,2'-methylene-bis (4-ethyl- 6-tert-butylphenol), 4,4′-butylidene-bis (6-tert-butyl-m-cresol), 2,2′-methylene-bis (4-methyl-6-cyclohexylphenol), 4,4 ′ -Bis (2,6-di-tert-butylphenol), 2,2'-dihydroxy-3,3'-bis (α-methylcyclohexyl) -5,5'-di Tildiphenylmethane, 4,4′-methylene-bis (2,6-di-tert-butylphenol), d, l-α-tocopherol (vitamin E), 2,6-bis (2-hydroxy-3-tert-butyl) -5-methylbenzyl) -4-methylphenol, 3- (4-hydroxy-3,5-di-tert-butylphenyl) propionate n-octadecyl, 1,3,5-tris (4-tert-butyl- 3-hydroxy-2,6-dimethylbenzyl) -s-triazine-2,4,6- (1H, 3H, 5H) -trione, 1,3,5-trimethyl-2,4,6-tris (3 5-di-tert-butyl-4-hydroxyphenyl) benzylbenzene, 1,3,5-tris (4-hydroxy-3,5-di-tert-butylbenzyl) -s-tria -2,4,6- (1H, 3H, 5H) -trione, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane, decamethylene dicarboxylic acid dissari Tyroyl hydrazide, N, N′-bis [3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionyl] hydrazine, 2,2′-oxyamido-bis-ethyl-3- (3,5 -Di-tert-butyl-4-hydroxyphenyl) propionate, 4,4'-thiobis (3-methyl-6-tert-butylphenol), 2,2'-thiobis (4-methyl-6-tert-butylphenol), bis ( 3-methyl-4-hydroxy-5-tert-butylbenzyl) sulfide, 4,4'-butylidene-bis (2-methyl-4- Droxy-5-tert-butylphenyl) -2-laurylthioether, 6- (4-hydroxy-3,5-di-tert-butylanilino) -2,4-bis (octylthio) -1,3,5-triazine, Examples include 2,4-bis (4-hydroxy-3,5-di-tert-butylanilino) -6- (n-octylthio) -1,3,5-triazine. Among these, tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane is particularly preferably used.

  In the present invention, the phenol-based heat stabilizer (D) is 0.02 to 0.3 with respect to 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softening agent (C). Part by weight, preferably 0.05 to 0.2 part by weight is used.

Non-phenol heat stabilizer (E)
The thermoplastic elastomer composition of the present invention can further improve the heat aging resistance by using a phenol heat stabilizer (D) and a heat stabilizer other than phenol. As heat-resistant stabilizers other than phenol-based ones, known heat-resistant stabilizers such as sulfur-based, phosphorus-based, and amine-based ones can be used, and among them, sulfur-based heat stabilizers are most preferable.

  The sulfur-based heat stabilizer used in the present invention is an organic compound containing a sulfur atom in the molecule and having a peroxide decomposition function. Specific examples of the sulfur-based heat stabilizer used in the present invention include 2-mercaptobenzimidazole, N, N′-diphenylthiourea, tetramethylthiuram disulfide, N-oxydiethylene-2-benzothiazolylsulfenamide. N-cyclohexyl-2-benzothiazolylsulfenamide, cyclohexylamine salt of 2-mercaptobenzothiazole, N, N-diisopropyl-2-benzothiazolylsulfenamide, 2- (N, N-diethylthiocarbamoylthio ) Benzothiazole, tetraethylthiuram disulfide, dibenzothiazyl disulfide, zinc diethyldithiocarbamate, zinc ethylphenyldithiocarbamate, zinc di-n-butyldithiocarbamate, dilaurylthiodipropionate, dilauri Thiodi-1,1'-methylbutyrate, Jimirisuchiru 3,3'-thiodipropionate, lauryl stearyl thiodipropionate, distearyl thiodipropionate, distearyl dibutyrate, dioctadecyl disulfide, and the like. Of these, zinc di-n-butyldithiocarbamate, distearyl thiodipropionate, distearyl thiodibutyrate and dioctadecyl disulfide are particularly preferably used.

  In the present invention, the heat-resistant stabilizer (E) other than phenolic, preferably the sulfur-based heat stabilizer, is added to 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softening agent (C). On the other hand, it is usually used in a proportion of 0.02 to 0.3 parts by weight, preferably 0.05 to 0.2 parts by weight.

Other components The thermoplastic elastomer composition of the present invention includes polyolefin (A), crosslinked rubber (B), softener (C), phenol-based heat stabilizer (D), and a heat-resistant stabilizer other than phenol ( In addition to E), an inorganic filler or the like can be blended.

  Specific examples of the inorganic filler include calcium carbonate, calcium silicate, clay, kaolin, talc, silica, diatomaceous earth, mica powder, asbestos, alumina, barium sulfate, aluminum sulfate, calcium sulfate, and basic magnesium carbonate. , Molybdenum disulfide, graphite, glass fiber, glass sphere, shirasu balloon, basic magnesium sulfate whisker, calcium titanate whisker, aluminum borate whisker, and the like.

  In the present invention, the inorganic filler is a total amount of polyolefin (A), cross-linked rubber (B) and softener (C) from the viewpoint of rubber elasticity and moldability of the thermoplastic elastomer composition obtained. It is usually used at a ratio of 100 parts by weight or less, preferably 2 to 50 parts by weight with respect to parts by weight.

  Furthermore, in the present invention, conventionally known weather resistance stabilizers, antistatic agents; lubricants such as metal soaps, waxes, silicone oils, and the like are added to the thermoplastic elastomer composition as long as the object of the present invention is not impaired. be able to.

  The thermoplastic elastomer composition of the present invention is blended with the above-described polyolefin (A), raw rubber (B ′) of a crosslinked rubber (B), a softener (C) and a predetermined heat stabilizer, as necessary. After mixing with an inorganic filler or the like, it is obtained by dynamically heat-treating in the presence of a crosslinking agent. Here, “dynamically heat-treating” means kneading in a molten state.

  Examples of the crosslinking agent used in the present invention include organic peroxides, phenol resins, sulfur, hydrosilicone compounds, amino resins, quinones or derivatives thereof, amine compounds, azo compounds, epoxy compounds, isocyanates, etc. Examples of the crosslinking agent generally used in mold rubbers. Of these crosslinking agents, organic peroxides are particularly preferred.

  Specific examples of the organic peroxide used in the present invention include dicumyl peroxide, di-tert-butyl peroxide, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2, 5-Dimethyl-2,5-di- (tert-butylperoxy) hexyne-3, 1,3-bis (tert-butylperoxyisopropyl) benzene, 1,1-bis (tert-butylperoxy) -3,3 5-trimethylcyclohexane, n-butyl-4,4-bis (tert-butylperoxy) valerate, benzoyl peroxide, p-chlorobenzoyl peroxide, 2,4-dichlorobenzoyl peroxide, tert-butylperoxybenzoate, tert-butylperoxyisopropyl Carbonate, diacetylpe Oxides, lauroyl peroxide, etc. tert- butyl cumyl peroxide.

  Among these, in terms of odor and scorch stability, 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane, 2,5-dimethyl-2,5-di- (tert-butyl) Peroxy) hexyne-3,1,3-bis (tert-butylperoxyisopropyl) benzene is preferred, and 2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane is most preferred.

  Such organic peroxides are polyolefin (A), crosslinked rubber (B), and softening agent in terms of heat resistance, tensile properties, elastic recovery, impact resilience, and moldability of the thermoplastic elastomer composition obtained. The total amount of (C) is usually 0.02 to 3 parts by weight, preferably 0.05 to 1.5 parts by weight, based on 100 parts by weight.

  In the crosslinking treatment with the organic peroxide, sulfur, p-quinonedioxime, p, p'-dibenzoylquinonedioxime, N-methyl-N-4-dinitrosoaniline, nitrosobenzene, diphenylguanidine, trimethylolpropane Crosslinking aids such as -N, N'-m-phenylene dimaleimide, divinylbenzene, triallyl cyanurate, or ethylene glycol dimethacrylate, diethylene glycol dimethacrylate, polyethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate Polyfunctional methacrylate monomers such as these; polyfunctional vinyl monomers such as vinyl butyrate and vinyl stearate can be blended.

  By using such a compound, a uniform and mild crosslinking reaction can be expected. In particular, divinylbenzene is most preferred in the present invention. Divinylbenzene is easy to handle, has good compatibility with the olefin resin (A), which is the main component of the cross-linked product, and rubbers such as ethylene / α-olefin / non-conjugated polyene copolymer rubber, and Because it has the action of solubilizing organic peroxides and acts as a dispersant for organic peroxides, a thermoplastic elastomer composition having a uniform crosslinking effect by heat treatment and a balance between fluidity and physical properties can be obtained. It is done.

  The crosslinking aid or the compound such as the polyfunctional vinyl monomer is usually 2 parts by weight with respect to 100 parts by weight of the total amount of the polyolefin (A), the crosslinked rubber (B) and the softening agent (C). Hereinafter, it is preferably used in an amount of 0.3 to 1 part by weight.

  In order to accelerate the decomposition of organic peroxide, tertiary amines such as triethylamine, tributylamine, 2,4,6-tri (dimethylamino) phenol, aluminum, cobalt, vanadium, copper, calcium, zirconium, Decomposition accelerators such as naphthenates such as manganese, magnesium, lead, and mercury may be used.

The dynamic heat treatment in the present invention is preferably performed in a non-open type apparatus, and is preferably performed in an atmosphere of an inert gas such as nitrogen or carbon dioxide. The temperature of heat processing is the range of 300 degreeC from melting | fusing point of polyolefin (A), and is 150-280 degreeC normally, Preferably it is 170-270 degreeC. The kneading time is usually 1 to 20 minutes, preferably 1 to 10 minutes. Further, the shear force applied is, 10～50,000Sec ^-1 shear rate, preferably in the range of 100~20,000sec ^-1.

  As a kneading apparatus, a mixing roll, an intensive mixer (for example, a Banbury mixer, a kneader), a single-screw or twin-screw extruder can be used, and a non-open type apparatus is preferable, and a twin-screw extruder is particularly preferable.

According to the present invention, a thermoplastic elastomer composition comprising a polyolefin (A), a crosslinked rubber (B) and the like is obtained by the dynamic heat treatment described above.
In the present invention, that the rubber in the thermoplastic elastomer composition is crosslinked means that the gel content measured by the following method is 20% by weight or more, preferably 30% by weight or more, More preferably, it is at least% by weight.

[Measurement method of gel content]
100 mg of a sample of the thermoplastic elastomer composition was sampled, and this sample cut into 0.5 mm × 0.5 mm × 0.5 mm strips was immersed in 30 ml of cyclohexane at 23 ° C. for 48 hours in a sealed container. Thereafter, the sample is taken out on a filter paper and dried at room temperature for 72 hours or more until a constant weight is obtained.

The value obtained by subtracting the weight of all cyclohexane-insoluble components (fibrous filler, filler, pigment, etc.) other than the polymer component and the weight of polyolefin (A) in the sample before cyclohexane immersion from the weight of this dry residue, The corrected final weight (Y) ”.
On the other hand, the weight of the rubber in the sample is defined as “corrected initial weight (X)”.

Here, the gel content is determined by the following formula.
Gel content [wt%]
= [Corrected final weight (Y) / corrected initial weight (X)] × 100

  The thermoplastic elastomer composition of the present invention is a highly heat-resistant aging thermoplastic elastomer composition in which the elongation at break after aging in an air oven at 130 ° C. for 500 hours retains 80% or more before aging.

EXAMPLES Hereinafter, although an Example demonstrates this invention, this invention is not limited to these Examples.
In addition, the measuring method of the physical property performed about the thermoplastic elastomer composition and its raw material in an Example and a comparative example is as follows.

[Measurement method of physical properties]
Tensile strength and elongation at break: measured according to JIS K6301. However, the tensile speed was 200 mm / min.
Bleed-out property: After aging the pressed sheet in a thermo-hygrostat kept at 40 ° C and 95% humidity, the bleed-out property of the stabilizer was evaluated according to the following criteria.

3: No bleed out of the stabilizer is observed.
2: The sheet surface is slightly whitened, and a slight bleedout of the stabilizer is observed.
1: The sheet surface is markedly whitened and the bleedout of the stabilizer is clearly observed.
Kinematic viscosity of softener: Measured according to JIS K2283.
Aniline point: Measured by a test tube method defined in JIS K2256.
Sulfur content: Measured by a microcoulometric titration method defined in JIS K2541.
% CP in ring analysis: Measured according to JIS K2536.
Total acid value: measured in accordance with JIS K2501.
Iodine value: The iodine value of the copolymer rubber was determined by a titration method.
Mooney viscosity: measured in accordance with JIS K6300.

The main raw materials used in Examples and Comparative Examples are as follows.
(A-1) Propylene homopolymer; MFR (ASTM D1238-65T, 230 ° C., 2.16 kg) 10 (g / 10 min)
(B-1) Oil-extended ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber: molar ratio of units derived from ethylene to units derived from propylene (ethylene / propylene) 79/21, iodine _No. 13, Mooney viscosity ML _{1 + 4} (100 ° C.) 140 parts by weight of polymer with 100 parts by weight of paraffinic mineral oil (C-1, Idemitsu Kosan Co., Ltd. PW-380; ring analysis% CP73, total acid value 0.01 ( mgKOH / g), ethylene / propylene / dicyclopentadiene copolymer rubber with 50 parts by weight of oil extended (B-2) oil-extended (aniline point 144 ° C., sulfur content 6 ppm, kinematic viscosity 382 centistokes at 40 ° C.) : Mole ratio of units derived from ethylene to units derived from propylene (ethylene / propylene) 80/20, iodine Valence 6, Mooney viscosity _{ML 1 + 4 (100 ℃)} 140 100 parts by weight of the polymer to the paraffinic mineral oil (C-2, manufactured by Idemitsu Kosan (Ltd.) PS-430;% in ring analysis CP72, total acid number 0.01 ( mgKOH / g), aniline point 133 ° C., sulfur content 1600 ppm, kinematic viscosity 438 centistokes at 40 ° C.) 40 parts by weight oil-extended (B-3) oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber: The ratio of units derived from ethylene to units derived from propylene (ethylene / propylene) 80/20, iodine number 6, Mooney viscosity ML _{1 + 4} (100 ° C.) 140 parts by weight of polymer was added to paraffinic mineral oil (C− 1, Idemitsu Kosan Co., Ltd. PW-380;% CP73 in ring analysis, total acid value 0.01 (mgKOH / g) or less , Aniline point 144 ° C., sulfur content 6 ppm, 40 kinematic viscosity 382 centistokes at ° C.) 40 parts by weight oil-extended

Example 1
25 parts by weight of propylene homopolymer (A-1) pellets, 75 parts by weight of oil-extended ethylene / propylene / 5-ethylidene-2-norbornene copolymer rubber (B-1) (50 parts by weight of rubber polymer) , Paraffin-based mineral oil 25 parts by weight) and phenol-based heat stabilizer tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane (product name: Irganox 1010, manufactured by Ciba Geigy) ) 0.1 part by weight, sulfur-based heat stabilizer zinc di-n-butyldithiocarbamate 0.1 part by weight, organic peroxide [2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane ] After adding 0.4 parts by weight and 0.6 parts by weight of divinylbenzene (DVB) and mixing well in a Henschel mixer, the biaxial And fed to extruder for dynamic heat treatment under the following conditions to obtain pellets of a thermoplastic elastomer.

Dynamic heat treatment condition extruder: Werner & Freder ZSK-53, screw diameter 53mm
Temperature setting: C1 / C2 / C3 / C4 / C5 / D = 140/160/180/220/220/200 (° C.)
Maximum shear rate: 2800 (sec ⁻¹ )
Extrusion amount: 50 (kg / hour)

  Next, this pellet was press-molded at 190 ° C. (preheating 6 minutes, pressure 4 minutes, cooling 5 minutes) to produce a sheet having a thickness of 1 mm, and punched out to produce a JIS-3 test piece, A tensile test was performed according to the measurement method to measure the tensile strength and elongation at break. Furthermore, the punched JIS-3 dumbbell was aged in an air oven maintained at 130 ° C. for 500 hours, and then the tensile strength and elongation at break were measured in the same manner. Further, the appearance change was visually confirmed after aging, and the color difference (ΔE) of the sample before and after aging was measured with a hunter color difference meter to evaluate discoloration due to heat aging. Further, the gel content was measured by the method described above and the bleed-out property was evaluated. The results are shown in Table 1.

(Example 2)
30 parts by weight of propylene homopolymer (A-1) pellets, 70 parts by weight of oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) (50 parts by weight of rubber polymer, paraffin mineral) Oil 20 parts by weight) and phenol-based heat stabilizer tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane (Ciba Geigy, trade name Irganox 1010) 0.1 Parts by weight, sulfur heat-resistant stabilizer distearyl thiodipropionate 0.1 parts by weight, organic peroxide [2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane] 0.2 parts by weight In addition, a dynamic heat treatment was carried out in a twin-screw extruder in the same manner as in Example 1 from 0.3 part by weight of divinylbenzene (DVB), and a thermoplastic elastomer It was obtained over the pellet.

  Next, this pellet was press-molded in the same manner as in Example 1 to prepare a JIS-3 test piece, and the tensile strength and elongation at break were measured in the same manner as in Example 1. Further, after aging in an air oven maintained at 130 ° C. for 500 hours as in Example 1, the tensile strength, elongation at break, appearance, and color difference were similarly measured. Further, the gel content was measured by the method described above and the bleed-out property was evaluated. The results are shown in Table 1. The results are shown in Table 1.

(Example 3)
In Example 2, 0.1 parts by weight of bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-di-phosphite was added as a phosphorus heat stabilizer in place of the sulfur heat stabilizer. Except for the above, thermoplastic elastomer pellets were prepared in the same manner as in Example 2 and evaluated in the same manner as in Example 2. The results are shown in Table 1.

Example 4
30 parts by weight of propylene homopolymer (A-1) pellets, 70 parts by weight of oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) (50 parts by weight of rubber polymer, paraffin mineral) Oil 20 parts by weight) and phenol-based heat stabilizer tetrakis [methylene-3- (3,5-di-tert-butyl-4-hydroxyphenyl) propionate] methane (Ciba Geigy, trade name Irganox 1010) 0.1 Parts by weight, sulfur-based heat stabilizer zinc di-n-butyldithiocarbamate 0.1 parts by weight, organic peroxide [2,5-dimethyl-2,5-di- (tert-butylperoxy) hexane] 0.2 Add parts by weight and 0.3 parts by weight of divinylbenzene (DVB) and mix thoroughly in a Henschel mixer. De to perform dynamic heat treatment under the following conditions to obtain pellets of a thermoplastic elastomer.

Dynamic heat treatment condition extruder: Werner & Freder ZSK-53, screw diameter 53mm
Temperature setting: C1 / C2 / C3 / C4 / C5 / D = 140/160/180/220/220/200 (° C.)
Maximum shear rate: 2800 (sec ⁻¹ )
Extrusion amount: 50 (kg / hour)

  Next, this pellet was press-molded at 190 ° C. (preheating 6 minutes, pressure 4 minutes, cooling 5 minutes) to produce a sheet having a thickness of 1 mm, and punched out to produce a JIS-3 test piece, A tensile test was performed according to the measurement method to measure the tensile strength and elongation at break. Furthermore, the punched JIS-3 dumbbell was aged in an air oven maintained at 130 ° C. for 500 hours, and then the tensile strength and elongation at break were measured in the same manner. Further, the appearance change was visually confirmed after aging, and the color difference (ΔE) of the sample before and after aging was measured with a hunter color difference meter to evaluate discoloration due to heat aging. Further, the gel content was measured by the method described above and the bleed-out property was evaluated. The results are shown in Table 1.

(Example 5)
In Example 4, 0.1 parts by weight of bis (2,6-di-tert-butyl-4-methylphenyl) pentaerythritol-di-phosphite was added as a phosphorus heat stabilizer in place of the sulfur heat stabilizer. Except for the above, thermoplastic elastomer pellets were prepared in the same manner as in Example 4 and evaluated in the same manner as in Example 4. The results are shown in Table 1.

(Example 6)
A pellet of thermoplastic elastomer was prepared in the same manner as in Example 4 except that the addition amount of the phenol-based heat stabilizer was 0.2 parts by weight in Example 4 and the sulfur-based heat stabilizer was not added. Evaluation was performed in the same manner. The results are shown in Table 1.

(Example 7)
Instead of the oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) in Example 4, an oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-3) was used. Except for the above, thermoplastic elastomer pellets were prepared in the same manner as in Example 4 and evaluated in the same manner as in Example 4. The results are shown in Table 1.

(Example 8)
The oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) was used in place of the oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) in Example 5. Except for the above, thermoplastic elastomer pellets were prepared in the same manner as in Example 5 and evaluated in the same manner as in Example 4. The results are shown in Table 1.

Example 9
In place of the oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-2) in Example 4, the oil-extended ethylene / propylene / dicyclopentadiene copolymer rubber (B-3) was used. Further, a thermoplastic elastomer pellet was prepared in the same manner as in Example 4 except that the addition amount of the phenol-based heat stabilizer was 0.2 parts by weight and the sulfur-based heat stabilizer was not added. Evaluation was made in the same manner as in Example 4. did. The results are shown in Table 1.

(Comparative Example 1)
Except that the phenol-based heat stabilizer and the sulfur-based heat stabilizer were not added in Example 1, thermoplastic elastomer pellets were prepared in the same manner as in Example 1 and evaluated in the same manner as in Example 1. The results are shown in Table 1.

(Comparative Example 2)
A pellet of thermoplastic elastomer was prepared in the same manner as in Example 2 except that the phenol-based heat stabilizer and sulfur-based heat stabilizer were not added in Example 2, and evaluation was performed in the same manner as in Example 2. The results are shown in Table 1.

(Comparative Example 3)
Except that no phenol-based heat stabilizer was added in Example 2, thermoplastic elastomer pellets were prepared in the same manner as in Example 2, and evaluated in the same manner as in Example 2. The results are shown in Table 1.

(Comparative Example 4)
A pellet of thermoplastic elastomer was prepared in the same manner as in Example 4 except that the phenol-based heat stabilizer and the sulfur-based heat stabilizer were not added in Example 4, and evaluation was performed in the same manner as in Example 4. The results are shown in Table 1.

(Comparative Example 5)
A pellet of thermoplastic elastomer was prepared in the same manner as in Example 4 except that the addition amount of the sulfur-based heat stabilizer was changed to 0.2 parts by weight without adding the phenol-based heat stabilizer in Example 4, and Example 4 and Evaluation was performed in the same manner. The results are shown in Table 1.

Claims (9)

10 to 60 parts by weight of polyolefin (A), at least one crosslinked rubber (B) selected from the group consisting of ethylene / α-olefin / non-conjugated polyene copolymer rubber and ethylene / α-olefin copolymer rubber 30 to 87 parts by weight and softener (C) 3 to 50 parts by weight (provided the total amount of (A), (B) and (C) is 100 parts by weight) and phenolic heat stabilizer (D) 0.02 to JIS after containing 0.3 part by weight and 0.02-0.3 part by weight of a heat stabilizer other than phenol selected from sulfur and phosphorus , after aging in an air oven at 130 ° C. for 500 hours A thermoplastic elastomer composition in which the elongation at break measured according to K6301 at a tensile rate of 200 mm / min holds 80% or more of the value before aging, wherein the softener (C) is JIS 2256 to a defined aniline point 120 to 140 ° C. as measured by a test tube method is, the thermoplastic elastomer composition is a sulfur 100~5,000ppm measured at trace coulometric drop formulation oxidation method specified in JIS K2541.   The thermoplastic elastomer composition according to claim 1, wherein the softener (C) has a kinematic viscosity at 40 ° C measured in accordance with JIS K2283 of 150 to 1000 centistokes. The thermoplastic elastomer composition according to claim 1 , wherein the heat-resistant stabilizer other than phenolic is a sulfur-based or phosphorus-based heat stabilizer. The thermoplastic elastomer composition according to claim 1 , wherein the heat-resistant stabilizer other than phenolic is a sulfur-based heat stabilizer.   The thermoplastic elastomer composition according to claim 1, wherein the crosslinked rubber (B) is an ethylene / α-olefin / non-conjugated polyene copolymer rubber.   The thermoplastic elastomer composition according to claim 1, wherein the polyolefin (A) is a propylene-based polymer resin and the crosslinked rubber (B) is an ethylene / α-olefin / non-conjugated polyene copolymer rubber. .   The thermoplastic elastomer composition according to claim 1, wherein the rubber is crosslinked with an organic peroxide.   The thermoplastic elastomer composition according to claim 1, which is produced using a twin-screw extruder. 10 to 60 parts by weight of polyolefin (A), at least one rubber (B ′) selected from the group consisting of ethylene / α-olefin / non-conjugated polyene copolymer rubber and ethylene / α-olefin copolymer rubber 30 to 30 Softener (87 parts by weight and an aniline point of 120 to 140 ° C. measured by a test tube method defined in JIS K2256, and a sulfur content of 100 to 5,000 ppm measured by a microcoulometric titration method defined in JIS K2541 C) 3 to 50 parts by weight [however, the total amount of (A), (B ′) and (C) is 100 parts by weight] and phenol-based heat stabilizer (D) 0.02 to 0.3 parts by weight , and sulfur the thermoplastic elastomer composition, characterized in that the system and heat stabilizers 0.02-0.3 parts by weight of the non-phenolic selected from the phosphorus-based heat-treating dynamically in the presence of a crosslinking agent The method of production.