JP2787844B2 - Hydrogenated block copolymer elastomer composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a hydrogenated block copolymer elastomer which is excellent in the deployability of an airbag and the splash resistance upon deployment in an airbag cover of an airbag system used as a safety device for automobiles and the like. It relates to a composition.

[0002]

2. Description of the Related Art Conventionally, an airbag cover is made of urethane containing a nylon net for reinforcement, and is inflated and deployed by folding an airbag stored inside.
It is designed to burst at a thin wall without a reinforcing nylon net. However, when such an airbag cover does not use a reinforcing nylon-based net, there is a problem that a crack is generated at the time of rupture other than a thin cleavage portion or the cover is scattered, and the reinforcing nylon-based net is used. In such a case, although the problem of cleavability during deployment of the airbag is solved, it takes time to align the reinforcing net during molding of the airbag cover, and the defect rate due to misalignment of the reinforcing nylon-based net increases or Due to the urethane RIM molding, there is a disadvantage that productivity is reduced. In addition, many airbag covers made of a thermoplastic resin that does not require a reinforcing nylon-based net have been studied.
It was very difficult for the airbag to reliably deploy at 40 ° C to 90 ° C, and for the airbag cover to not crack other than at the cleaved portion when the airbag was deployed and for the fragments to never scatter. Among them, some polyolefin-based thermoplastic resins have a temperature of −40 ° C. to 90 ° immediately after molding.
Despite having good development performance at ℃, the high-temperature aging test, or the high-temperature aging test, due to changes in physical properties due to changes in the phase structure such as changes in the crystallinity of the polyolefin-based thermoplastic resin after the weather resistance test, After the test, the deployability of the airbag at a temperature of −40 ° C. to 90 ° C. and the scatter resistance during the deployment are not satisfactory. As described above, an airbag cover having a hardness of 40 to 90 and having excellent deployment performance not only immediately after molding but also after a high-temperature aging test and a weather resistance test has not been developed.

[0003]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and cannot be achieved with urethane containing a reinforcing nylon net in an airbag cover of an airbag system used as a safety device for automobiles and the like. JISK63 that does not require a reinforced nylon net
An object of the present invention is to provide a novel hydrogenated block copolymer composition used for an airbag cover having a spring hardness (hardness) of 40 to 90. As a result of various studies, the inventors of the present invention have found that the hydrogenated block copolymer of the component a is used as a main component, and the developing performance on the low-temperature side is improved with the hydrogenated block of the component b, which has a higher molecular weight than the component a. It is improved by adding and alloying a copolymer rubber of the polymer and the component e or a thermoplastic elastomer of the component f, and the developability on the high temperature side is a hydrogenated block copolymer composition of the component b having a higher molecular weight than the component a. A blend design concept that improves by adding and alloying a copolymer of propylene of the component and propylene of component c and an α-olefin having 2 to 8 carbon atoms, and develops and develops in a wide temperature range of -40 ° C to 90 ° C. It is possible to obtain an airbag cover with excellent splash resistance at the time, and by an optimal combination of these, not only immediately after molding but also after a high temperature aging test and a weather resistance test, in a wide temperature range of −40 ° C. to 90 ° C. Deployment , I found that to obtain an air bag cover having excellent scattering property during deployment, in which the present invention has been completed.

[0004]

That is, the present invention relates to a method for preparing a component a, b, c, d, e or a, b, c,
This is a hydrogenated block copolymer elastomer composition for an airbag cover obtained by melting and kneading d and f to form a pellet. (A) hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly composed of a vinyl aromatic compound and at least one intermediate polymer block B mainly composed of a conjugated diene compound; The obtained hydrogenated block copolymer having a spring hardness (JIS K6301) of 99 or less and a number average molecular weight of 20000 to 100000 100 parts by weight (b) Mainly at least two vinyl aromatic compounds A hydrogenated block copolymer obtained by hydrogenating a block copolymer consisting of a terminal polymer block A to be converted and an intermediate polymer block B mainly composed of at least one conjugated diene compound, has a spring hardness (JIS K6301). ) Is 99 or less and has a number average molecular weight of 10,000 to 200,000 10 to 150 parts by weight (c) propylene and carbon Copolymers with 2 to 8 α-olefins having a heat distortion temperature of 90 ° C. or higher 10 to 300 parts by weight (d) Paraffinic oil 2 to 300 parts by weight (e) Ethylene-α-olefin copolymer A rubber having a glass transition point of -30 ° C. or less from 2 to 100 parts by weight of a coalesced rubber and / or an ethylene-α-olefin-non-conjugated diene copolymer rubber; A brittle thermoplastic elastomer composed of a blend of an olefin copolymer rubber and a polyolefin resin or a blend of a dynamically vulcanized ethylene-α-olefin-nonconjugated diene copolymer rubber and a polyolefin resin. Those having an oxidation temperature of -50 ° C or less 2 to 100 parts by weight

Hereinafter, the present invention will be described in detail. The hydrogenated block copolymer used in the present invention comprises at least two terminal polymer blocks A mainly composed of a vinyl aromatic compound and at least one intermediate polymer block B mainly composed of a conjugated diene compound. Is obtained by hydrogenating a block copolymer having the structure represented by the following general formula, which is obtained by hydrogenating a block copolymer of a vinyl aromatic compound and a conjugated diene compound. A- (BA) n (1 ≦ n ≦ 5) In order to obtain a hydrogenated block copolymer elastomer composition, a hydrogenated block copolymer having a hardness of 99 or less, preferably 90 or less is used. Therefore, when the vinyl aromatic compound is contained in an amount of 5 to 50% by weight, preferably 10 to 40% by weight, and the block structure is mentioned, the terminal polymer A mainly composed of the vinyl aromatic compound is A compound polymer block or a copolymer block of a vinyl aromatic compound containing more than 50% by weight, preferably 70% by weight or more of a vinyl aromatic compound and a hydrogenated conjugated diene compound, Further, the intermediate polymer block B mainly composed of a hydrogenated conjugated diene compound is used as a hydrogenated conjugated diene compound polymer block or a hydrogenated conjugated diene compound. The emissions Compound 5
It has a structure of a copolymer block of a hydrogenated conjugated diene compound and a vinyl aromatic compound containing more than 0% by weight, preferably 70% by weight or more. When there are two or more polymer blocks mainly composed of a vinyl aromatic compound and two or more polymer blocks mainly composed of a hydrogenated conjugated diene compound, each of the polymer blocks may have the same structure or may have different structures. It may have a structure. Examples of the vinyl aromatic compound constituting the hydrogenated block copolymer include styrene, α-methylstyrene, vinyltoluene, and p-tert-butylstyrene.
The species or two or more species can be selected, and among them, styrene is preferred. Examples of the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound include, for example, butadiene,
One or more kinds are selected from isoprene, 2.3-dimethyl-1.3-butadiene and the like, and among them, butadiene, isoprene and a combination thereof are preferable.
Further, the molecular structure of the hydrogenated block copolymer may be linear, branched, radial, or any combination thereof.

The number average molecular weight (Mn) of the hydrogenated block copolymer of the component a used in the present invention is from 20,000 to 10
The molecular weight distribution Mw / Mn is 10 or less (Mw: weight average molecular weight), preferably 5 or less, more preferably 2 or less. When the number average molecular weight is less than 20,000, sufficient heat resistance cannot be imparted, and when it is more than 100,000, when combined with the component b, the fluidity during molding is significantly impaired. If the molecular weight distribution exceeds 10, strength,
Heat resistance decreases.

The hydrogenated block copolymer (b) has a number average molecular weight (Mn) in the range of 100001 to 200,000, preferably 1100 to 150,000, and a molecular weight distribution M
w / Mn is 10 or less (Mw: weight average molecular weight);
The compounding amount is 10 to 15 with respect to 100 parts by weight of the component a.
0 parts by weight, preferably 20 to 100 parts by weight. When the number average molecular weight is less than 100001, when combined with the component a, sufficient heat resistance cannot be imparted,
If it is larger than 200,000, the fluidity during molding is significantly impaired. If the molecular weight distribution exceeds 10, the strength and heat resistance decrease. If the blending amount of the component (b) is less than 10 parts by weight with respect to 100 parts by weight of the component (a), good deployment performance cannot be exhibited when the airbag cover is deployed at -40 ° C.
If it exceeds 0 parts by weight, the fluidity during molding is significantly impaired. In addition, since the hydrogenated block copolymer of the component b has a large number average molecular weight, in order to improve workability, an oil-extended paraffinic oil of the component d described below can be appropriately used.

Next, a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, which is used as the component c of the present invention, is effective for improving the processability and heat resistance of the obtained composition. Random or block copolymers of propylene and other small amounts of α-olefins, specifically polypropylene-ethylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1pentene copolymers, and poly4 -Methyl-1-pentene, polybutene-1, etc., among which ethylene-propylene block copolymers are preferred, and those having an ethylene content of 2 to 30% by weight are preferred. Further, a nucleating agent is preferably added in order to suppress a change in physical properties in a high-temperature aging test and a weather resistance test. The melt flow rate of the copolymer of propylene and an α-olefin having 2 to 8 carbon atoms (ASTM-D-1238L conditions, 230 ° C.) is 0.1 to 50 d.
g / min, especially those in the range of 0.5 to 30 dg / min can be suitably used. Melt flow rate is 0.1dg
If it is less than / min, the fluidity at the time of molding is deteriorated, and
If it is larger than / min, the heat resistance is undesirably reduced. Here, the heat distortion temperature (JIS K7207 4.6kgf / cm ² )
Is limited to 90 ° C. or higher because if the temperature is lower than 90 ° C., there is no effect on improving heat resistance. The amount of the component (c) is 10 to 300 parts by weight, preferably 40 to 150 parts by weight, per 100 parts by weight of the component (a). If the amount of the component (c) is less than 10 parts by weight based on 100 parts by weight of the component (a), sufficient heat resistance cannot be imparted. Deployment performance cannot be demonstrated.

[0009] The paraffinic oil of the d component used in the present invention is an essential component having an effect of adjusting the hardness of the obtained composition and giving flexibility. Generally, rubber softening, volume expansion,
The mineral oil-based rubber softener called process oil or extender oil used for improving processability is a mixture of an aromatic ring, a naphthene ring, and a paraffin chain. Those occupying 50% or more of the number are called paraffinic, those having 30 to 45% naphthenic ring carbon are naphthenic, and those having more than 30% aromatic ring carbon are aromatic. The oil used as the component b in the present invention is preferably a paraffinic oil in the above category, and a naphthenic or aromatic oil is not preferred in terms of dispersibility and solubility. The paraffin rubber softener has a kinematic viscosity at 37.8 ° C. of 20 to 50.
0 cst, pour point -10 to -15 ° C and flash point 1
Indicates 70 to 300 ° C. The amount of the paraffinic oil of the component d is 2 to 300 parts by weight, preferably 5 to 100 parts by weight, per 100 parts by weight of the component a. When the amount of the component (d) is less than 2 parts by weight per 100 parts by weight of the component (a), the resulting composition is close to the resin composition, so that the hardness is increased and the flexibility is lost. Absent. The amount of the component d is 30 per 100 parts by weight of the component a.
If the amount exceeds 0 parts by weight, the softener tends to bleed out and may cause tackiness in the final product.
Decreases mechanical properties.

Further, the copolymer rubber used as the component e in the present invention is an essential component for improving the airbag expandability at -40 ° C. As the α-olefin in the ethylene-α-olefin copolymer rubber and / or the ethylene-α-olefin-nonconjugated diene copolymer rubber, one having 3 to 15 carbon atoms is suitable. As the non-conjugated diene, dicyclopentadiene, 1,4-hexadiene, ethylidene norbornene, methylene norbornene and the like can be used. In the present invention, polypropylene is suitable as the α-olefin from the viewpoint of easy availability and improvement of impact resistance. Therefore, as the e component, so-called EPR, EPDM
Is suitable. The ethylene / α-olefin ratio of the copolymer rubber is preferably 50/50 to 90/10 by weight, more preferably 60/40 to 80/20. Here, the reason why the glass transition point is specified to be −30 ° C. or lower is that those having a glass transition point exceeding −30 ° C. cannot improve the airbag deployability at −40 ° C. The amount of the component (e) can be selected in the range of 2 to 100 parts by weight, preferably 5 to 80 parts by weight, per 100 parts by weight of the component (a). When the amount of the component e is less than 2 parts by weight based on 100 parts by weight of the component a, the improvement of the airbag expandability at -40 ° C as an effect of adding the copolymer rubber is not recognized, which is not preferable. If the amount of the component (e) exceeds 100 parts by weight based on 100 parts by weight of the component (a), the strength of the obtained elastomeric composition at a high temperature cannot be maintained, and 9
Not only is the airbag expandability at 0 ° C unfavorable, but also the heat-resistant shape retention at high temperatures is significantly deteriorated, making it unsuitable for use as a molded product.

The thermoplastic elastomer used as the component f in the present invention is a component for improving the expandability of the airbag at -40 ° C., and the α-olefin in the copolymer rubber has 3 to 15 carbon atoms. Suitable. Non-conjugated dienes include dicyclopentadiene, 1,4-hexadiene,
Ethylidene norbornene, methylene norbornene and the like can be used. In the present invention, polypropylene is suitable as the α-olefin from the viewpoint of easy availability and improvement of impact resistance. Accordingly, the ethylene-α-olefin-nonconjugated diene copolymer rubber in the f component is a so-called EP
DM is preferred. The ethylene / α-olefin ratio of the copolymer rubber is preferably 50/50 to 90/10, more preferably 60/40 to 80/20 by weight. As the vulcanizing agent, an ordinary vulcanizing agent for rubber can be used, and in addition to sulfur, an organic peroxide such as an alkylphenol / formaldehyde resin and dicumyl peroxide is particularly preferably used. In addition to the vulcanizing agent, a vulcanizing aid, an antioxidant and the like may be used in combination. The amount of the alkylphenol-formaldehyde resin to be added is 0.1 to 100 parts by weight of the copolymer rubber.
The range of 5 to 15 parts by weight is preferable from the viewpoint of balance between strength and workability. In the case of an organic peroxide, copolymer rubber 100
The range of 0.05 part by weight to 1 part by weight with respect to part by weight is preferable from the viewpoint of balance between strength and workability. Copolymer rubber 10
It is indispensable to contain 5 parts by weight or more of the polyolefin resin with respect to 0 parts by weight in order to maintain processability. While dynamically blending and kneading a blend of a copolymer rubber and a polyolefin resin, a vulcanizing agent is added and vulcanized to form the component f.
Can be obtained. The reason for setting the embrittlement temperature of the thermoplastic elastomer to -50 ° C or lower is that those having a higher embrittlement temperature cannot improve the airbag deployability at -40 ° C. The amount of the component f can be selected in the range of 2 to 100 parts by weight, and preferably in the range of 5 to 80 parts by weight, per 100 parts by weight of the component a. If the amount of the component f is less than 10 parts by weight based on 100 parts by weight of the component a, no improvement in the airbag deployability at -40 ° C. as an effect of adding the copolymer rubber is recognized, which is not preferable. f component is a
If the amount is more than 100 parts by weight with respect to 100 parts by weight of the component, the strength of the obtained elastomeric composition at high temperature cannot be maintained, and not only the airbag expandability at 90 ° C. is not favorable, but also the heat-resistant shape retention at high temperature Its properties are remarkably deteriorated and it cannot be used as a molded product.

In addition to the above-mentioned components (a) to (e), the composition of the present invention can further contain an inexpensive resin such as an inorganic filler and a polystyrene resin, if necessary. . These not only have the benefit of reducing product costs as extenders, but also have a positive effect on quality improvement (inorganic fillers: heat-resistant shape retention, flame retardancy, etc. Polystyrene resins: processability improvement, etc.) There are also advantages to give. Examples of inorganic fillers include calcium carbonate, carbon black, talc, magnesium hydroxide, mica, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon),
There are titanium oxide and the like, and as the carbon black, channel black, furnace black and the like can be used. Of these inorganic fillers, talc and calcium carbonate are economically advantageous and preferred. Further, as the polystyrene resin usable for this purpose, those obtained by a radical polymerization method or an ionic polymerization method can be suitably used, and the number average molecular weight thereof is 5,000 to 500,000, preferably 1,000.
The molecular weight distribution Mw can be selected from the range of 0 to 200,000.
/ Mn is preferably 5 or less. Further, if necessary, a nucleating agent, an outer lubricant, an inner lubricant, a hindered amine light stabilizer, a hindered phenol antioxidant, a coloring agent, a silicone oil and the like may be added.

The method for producing the composition of the present invention includes:
A general method used for producing a usual resin composition or rubber composition can be employed. Basically, it is a mechanical melt-kneading method, and a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders, Brabender, rolls and the like are used for these. At this time, the order of addition of each component is not limited.For example, all components are premixed by a mixer such as a Henschel mixer or a blender and melt-kneaded by the above-described kneader, or any component is premixed and master batch It is possible to employ an addition method in which the components are melt-kneaded, the remaining components are added, and the mixture is melt-kneaded. At this time, the melting and kneading temperature is 1
It can be suitably selected from 80 ° C to 300 ° C. The hydrogenated block copolymer composition obtained here is further supplied to an injection molding machine provided with a mold for an airbag cover, and injection molded in a short time to obtain an airbag cover. Unnecessary burrs, runner portions, and spool portions of the injection-molded product can be recycled because the composition of the present invention is thermoplastic, and can be reused as a material for an airbag cover.

[0014]

EXAMPLES Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples. The components blended in the following Examples and Comparative Examples are as follows. <Component a> Tuftec H1071 manufactured by Asahi Kasei Kogyo Co., Ltd. It has a polystyrene-hydrogenated polybutadiene-polystyrene structure, a bound styrene content of 20% by weight, and a number average molecular weight of about 70000 [Hardness: 67 (JIS K630)
1)] <Component b> Tuftec H1272 manufactured by Asahi Kasei Kogyo Co., Ltd .: having a structure of polystyrene-hydrogenated polybutadiene-polystyrene, having a bound styrene content of 35% by weight and a number average molecular weight of about 120,000 (paraffin oil [Diana, manufactured by Idemitsu Kosan Co., Ltd. Process oil PW-380 [paraffinic process oil, kinematic viscosity: 381.6 cst (40 ° C.),
30.1 (100 ° C.), average molecular weight 746, ring analysis value:
CA = 0%, CN = 27%, CP = 73%]] 35% by weight
Oil hardness) [Hardness: 40 (JIS K6301)] <Component c-1> Asahi Kasei Kogyo's ethylene-propylene block copolymer: Asahi Polypro M7646: Melt flow rate 15 dg / min (ASTM D1238), heat distortion temperature 120 ° C (ASTM D648 [4.6 f /
2]) <Component c-2> Polypropylene manufactured by Asahi Kasei Kogyo: Asahi Polypro M1700: Melt flow rate 31 dg / min
(ASTM D1238), heat deformation temperature 119 ° C (AS
TM D648 [4.6 f / 2]) <Component d> Diana Process Oil PW-3 manufactured by Idemitsu Kosan
80 [paraffinic process oil, kinematic viscosity: 381.
6 cst (40 ° C.), 30.1 (100 ° C.), average molecular weight 746, ring analysis: CA = 0%, CN = 27%, CP =
<Component e-1> Ethylene-propylene copolymer rubber EP07P made by Japan Synthetic Rubber [propylene content: 25% by weight]
MFR (230 ° C.) = 0.7 g / 10 min Tg: −38
° C] <Component e-2> Ethylene-propylene made by Japan Synthetic Rubber
Ethylidene norbornene copolymer rubber EP57P [propylene content: 28% by weight MFR (230 ° C.) = 0.4 g
/ 10 min Iodine value: 15.0 Tg: -40 ° C] <Component f> Sumitomo Chemical Sumitomo TPE3570 [vulcanizing agent: organic peroxide embrittlement temperature: -60 ° C>]

In Examples 1 to 8 and Comparative Examples 1 to 5, the components having the mixing ratios shown in the table were sufficiently dry-blended, and then melted using a twin-screw kneader under the condition that the resin temperature reached 220 to 270 ° C. It was kneaded and extruded to pelletize. The following evaluation was performed using this pellet. (1) Hardness (JIS K6301): A press sheet was prepared and measured. (2) Appearance: Using an injection molding machine, a molded product of the airbag cover having a thickness of 0.5 mm at the cleavage portion of the airbag cover and a thickness of 2 to 5 mm other than the cleavage portion of the airbag cover is produced.
The appearance such as flow mark and gloss was visually observed. Good was evaluated as O, slightly poor as Δ, and poor as X. (3) Heat-resistant shape retention: This airbag cover molded product is heated to a temperature of 1
A heat-resistant shape retention test was performed in an environment of 10 ° C. After 24 hours, the sample having good shape retention and no sagging, etc. was evaluated as ○, and the sample having sagging, etc. was evaluated as ×. (4) Deployment test: (4) -1. Normal condition: This airbag cover molded product was placed at an ambient temperature of 9
An airbag deployment test was performed at 0 ° C, 23 ° C, and -40 ° C. The sample that satisfactorily expanded from the cleaved portion of the airbag cover was rated as ○, and the sample that cracked or scattered the cover other than the cleaved portion of the airbag cover, and the sample that did not deploy the airbag satisfactorily was rated as x. (4) -2. After high-temperature aging test: This molded airbag cover was subjected to a high-temperature aging test in an environment at a temperature of 110 ° C. After 400 hours of high temperature aging test, environmental temperature 90 ° C, 23 ° C and -4
An airbag deployment test was performed at 0 ° C. The sample that satisfactorily expanded from the cleaved portion of the airbag cover was rated as ○, and the sample that cracked or scattered the cover other than the cleaved portion of the airbag cover, and the sample that did not deploy the airbag satisfactorily was rated as x. The results are shown in Tables 1 and 2 as examples, and in Table 3 as comparative examples. The composition ratios in the table are parts by weight,
The numerical value in parentheses of component b in the table is the number of parts excluding the oil-extended oil component in component b, and the numerical value in parentheses of component d in the table is the number of parts of the oil-extended oil component in component b. This is the number of copies added to the number of copies of the component d. From these results, it can be seen that the airbag cover formed from the composition obtained in the present invention has a hardness of 40 to 90 and is excellent in airbag deployability at -40 to 85 ° C.

[0016]

[0017]

[0018]

[0019]

The airbag cover molded from the composition of the present invention has a good airbag deployment without cracking or scatter of the cover other than at the cracked portion when the airbag is deployed between -40 ° C and 90 ° C. Is obtained. In addition, it has excellent long-term reliability such as high-temperature aging resistance and weather resistance. Moreover, compared to conventional urethane and reinforcing nylon nets, the utility value thereof is very large, such as good moldability, good productivity, simple color matching, and low cost.

──────────────────────────────────────────────────続 き Continuation of the front page (51) Int.Cl. ⁶ identification code FI C08L 91/08 C08L 91/08 (58) Investigated field (Int.Cl. ⁶ , DB name) C08L 23/00-23/36 C08L 53/00-53/02

Claims (1)

(57) [Claims] 1. A hydrogenated block copolymer elastomer composition comprising the following components a, b, c, d and e or f. (A) hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly composed of a vinyl aromatic compound and at least one intermediate polymer block B mainly composed of a conjugated diene compound; The obtained hydrogenated block copolymer has a spring hardness (JIS K6301) of 99 or less and a number average molecular weight of 20000 to 100000 100 parts by weight (b) Mainly at least two vinyl aromatic compounds A hydrogenated block copolymer obtained by hydrogenating a block copolymer composed of a terminal polymer block A and at least one intermediate polymer block B mainly composed of a conjugated diene compound, and having a spring hardness (JIS K6301) Is not more than 99 and has a number average molecular weight of 10,000 to 200,000 10 to 150 parts by weight (c) propylene and carbon number Copolymers with α-olefins having a heat distortion temperature of 90 ° C. or higher 10 to 300 parts by weight (d) Paraffinic oil 2 to 300 parts by weight (e) Ethylene-α-olefin copolymer Rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C or less 2 to 100 parts by weight (f) Dynamically vulcanized ethylene-α-olefin Embrittlement of thermoplastic elastomers consisting of a blend of copolymer rubber and polyolefin resin or a blend of dynamically vulcanized ethylene-α-olefin-non-conjugated diene copolymer rubber and polyolefin resin Those having a temperature of -50 ° C or less 2 to 100 parts by weight