JP2989136B2 - Thermoplastic 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 an airbag cover for an airbag system used as a safety device for automobiles and the like, which is excellent in the deployability of the airbag, the splash resistance at the time of deployment, and the thermoplastic resin which does not require painting. The present invention relates to an elastomer composition.

[0002]

2. Description of the Related Art Conventionally, an airbag cover has been made of urethane having a reinforcing nylon net inserted therein, and there is no reinforcing nylon net due to inflation and deployment of an airbag folded and stored inside. It is designed to burst at the thin part. However, when such an airbag cover does not use a reinforcing nylon-based net, there occurs a problem that a crack is generated in addition to a thin-walled rupture portion at the time of rupture or a cover is scattered, and the reinforcing nylon-based net is used. In this case, although the problem of tearability during deployment of the airbag is solved, it takes time to align the reinforcing net when molding the airbag cover, and the defect rate due to misalignment of the reinforcing nylon net increases. Alternatively, there is a disadvantage that productivity is reduced due to urethane RIM molding.

A number of airbag covers made of a thermoplastic resin which does not require a nylon net for reinforcement have also been studied. However, these airbag covers have a hardness of 60 to 99 and have a softness that is not unpleasant for humans as an automobile interior part. The airbag is reliably deployed at a temperature of -40C to 90C,
It was very difficult for the airbag cover to crack other than the cleaved portion when the airbag was deployed, and for the fragments to never scatter. Among them, in some polyolefin-based thermoplastic resins, in a state immediately after molding, the temperature is −40 ° C. to 9 ° C.
Although these materials have good development performance at 0 ° C., due to changes in physical properties accompanying changes in the phase structure such as changes in the crystallinity of the polyolefin-based thermoplastic resin after a high-temperature aging test or a weather resistance test, these high-temperature aging tests and weather resistance After the water resistance 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 60 to 99 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.

Further, most of these air bag covers which are currently being studied are coated in order to suppress discomfort such as scratches due to nails and clothes, unpleasant touch such as stickiness, and discoloration due to sunlight. -An airbag cover that does not require painting has been demanded from the viewpoint of economy. Up to now, organic lubricants such as higher fatty acids, higher fatty acid esters, and higher fatty acid amides, and low-viscosity silicone oil have been added to improve the scratch resistance or to prevent stickiness, and to increase the surface slipperiness of molded products. Attempts have been made to improve it. However, these materials are remarkably transferred to the surface with the passage of time or heat, so that there is a problem that the appearance of the molded product is impaired or the scratch resistance is reduced.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art, and provides a urethane-coated product in which a reinforcing nylon net is inserted in an airbag cover of an airbag system used as a safety device for an automobile or the like. JIS that does not require a nylon net for reinforcement that could not be done
An object of the present invention is to provide a novel thermoplastic elastomer composition used for an unpainted airbag cover having a K6301 spring hardness (hardness) of 60 to 99.

[0006]

As a result of various studies, the present inventors have found that among styrene elastomers known as hydrogenated block copolymers of the component a, those having a number average molecular weight of 50,000 or more are particularly desirable. As a main component, by adding a copolymer rubber of the d component or a thermoplastic elastomer of the e component and alloying it to improve the developing performance on the low temperature side,
By adding and alloying a copolymer of propylene of the component b and an α-olefin having 2 to 8 carbon atoms, the developing performance on the high temperature side is improved, and the viscosity of the component f is at least 50,000 centistokes or more by a silicone oil. The compounding design concept of improving scratch resistance and stickiness is -40.
It is possible to obtain an airbag cover excellent in deployability and splash resistance during deployment in a wide temperature range of ℃ to 90 ° C, and by the optimal combination of these, not only immediately after molding but also a high-temperature aging test and a weather resistance test Later, it was found that an airbag cover that does not require painting with excellent deployability and excellent splash resistance during deployment in a wide temperature range of −40 ° C. to 90 ° C.
The present invention has been completed.

That is, the present invention relates to the following components a, b,
Excellent in high-temperature and low-temperature deployability suitable for an airbag cover obtained by melting and kneading c, d, f or components a, b, c, e, f, and components a, b, c, d + e, f, and pelletizing. It is intended to provide a thermoplastic elastomer composition. (A) A hydrogenated 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 number average molecular weight of 50,000 or more 5
(B) a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms having a heat distortion temperature of 90 ° C. or more;
60% by weight (c) Paraffin-based oil 5 to 50% by weight (d) Glass transition point of -30 ° C among ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber (E) a blend of a dynamically vulcanized ethylene-α-olefin copolymer rubber and a polyolefin resin, or
An embrittlement temperature of a thermoplastic elastomer composed of a blend of a dynamically vulcanized ethylene-α-olefin-nonconjugated diene copolymer rubber and a polyolefin-based resin has a brittle temperature of -50
° C or less, and (d) and / or (e) are 5-70
% By weight (f) Viscosity (JIS Z8803, 25 ° C) is 5000
0.1 to 10% by weight of silicone oil that is not less than 0 centistokes (hereinafter abbreviated as cst)

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION 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) The hydrogenated block copolymer has a hardness of 99 or less, preferably 90 or less, and is a vinyl aromatic compound having a hardness of 5 to 50.
% By weight, preferably 10 to 40% by weight, and when the block structure is further referred to, the terminal polymer A mainly composed of a vinyl aromatic compound contains 50% by weight of a vinyl aromatic compound polymer block or a vinyl aromatic compound. Having a structure of a copolymer block of a vinyl aromatic compound and a hydrogenated conjugated diene compound containing at least 70% by weight and a hydrogenated conjugated diene compound. The polymer block B contains a hydrogenated conjugated diene compound polymer block or a hydrogenated conjugated diene compound in an amount of more than 50% by weight, preferably 70% by weight or more, and a vinyl aromatic compound. It has a structure of a copolymer block with a compound. 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 be different. It may have a structure.

As the vinyl aromatic compound constituting the hydrogenated block copolymer, one or more of styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like can be selected. Among them, styrene is preferred. As the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound, for example, one or more selected from butadiene, isoprene, 2.3-dimethyl-1.3-butadiene and the like are selected. Among them, butadiene, isoprene and a combination thereof are preferred. 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 50.
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 50,000,
Sufficient heat resistance cannot be provided. If the molecular weight distribution exceeds 10, the strength and heat resistance decrease. The amount of the component a is 5 to 50% by weight, preferably 10 to 45% by weight.
% By weight. If the amount of the component (a) is less than 5% by weight, sufficient strength or impact resistance cannot be imparted at both high and low temperatures. A molded article having a good appearance cannot be obtained. Further, the hydrogenated block copolymer of the component a has a large number average molecular weight, so as to improve workability,
An oil extension of a paraffinic oil of the component c described below can be used as appropriate.

Next, a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms, which is used as the component b 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 propylene-ethylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1pentene copolymers, and propylene- Polybutene-1 and the like can be mentioned, and among them, a propylene-ethylene block copolymer is preferable, and among them, those having an ethylene content of 2 to 30% by weight are preferable. 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 60 g / 10 min, particularly 0.5
Those having a range of ５０50 g / 10 min can be suitably used. If the melt flow rate is less than 0.1 g / 10 min, the fluidity during molding deteriorates, and if it is greater than 60 g / 10 min, the heat resistance decreases, which is not preferable. In addition, the reason why the heat distortion temperature (JIS K7207 4.6 kgf / cm ² ) is limited to 90 ° C. or higher is that if it is lower than 90 ° C., there is no effect in improving heat resistance. As the compounding amount of the component b, 20 to 60
%, Preferably 30 to 50% by weight. b
If the compounding amount of the component is less than 20% by weight, sufficient heat resistance cannot be imparted, and if it exceeds 60% by weight, the impact resistance at low temperatures is remarkably reduced. Good deployment performance cannot be exhibited during deployment.

The paraffinic oil of the component c used in the present invention is an essential component having an effect of adjusting the hardness of the resulting 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 aromatic rings, naphthene rings, and paraffin chains. The paraffin chain has all carbon atoms. 50% of the number
Those occupying the above are called paraffinic, those having a naphthene ring carbon number of 30 to 45% are naphthenic, and those having an aromatic ring carbon number exceeding 30% are aromatic. The oil used as the component c of the present invention is 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 17
0 to 300 ° C. The compounding amount of the paraffinic oil of the component c is 5 to 50% by weight, preferably 10 to 30% by weight. If the amount of the component (c) is less than 5% by weight, the resulting composition is close to the resin composition, so that the hardness is increased, the flexibility is lost, and it is not preferable from an economic viewpoint. If the amount of the component (c) is more than 50% by weight, the softener tends to bleed out and may cause tackiness in the final product, which is not preferable because it lowers the mechanical properties.

Further, the copolymer rubber used as the component d 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 d 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 d is 5-7.
0% by weight, preferably from 10 to 6% by weight.
5% by weight. When the amount of the component d is less than 5% by weight, 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 (d) exceeds 70% by weight, the obtained elastomeric composition cannot maintain the strength at a high temperature, and not only is the airbag deployability at 90 ° C unfavorable, but also the heat-resistant shape retention at a high temperature is significantly deteriorated. Does not withstand use as a molded product.

The thermoplastic elastomer used as the component e in the present invention is a component for improving the air bag expandability 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. Therefore, the ethylene-α-olefin-non-conjugated diene copolymer rubber in the component e 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. In particular, an organic peroxide such as alkylphenol / formaldehyde resin and dicumyl peroxide is particularly preferably used in addition to sulfur. 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 e.
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 e can be selected in the range of 5 to 70% by weight, and preferably in the range of 10 to 65% by weight. If the content of the component e is less than 5% by weight, no improvement in the airbag expandability at -40 ° C as an effect of adding the copolymer rubber is recognized, which is not preferable. If the component e exceeds 70% by weight, the obtained elastomeric composition cannot maintain the strength at a high temperature, the airbag expandability at 90 ° C. is not favorable, and the heat-resistant shape retention at a high temperature is significantly deteriorated. Does not withstand use as a molded product. Further, the d component and the e component may be used as a mixture. In that case, the added amount is in the range of 5 to 70% by weight in total of both components.

The silicone oil, which is the component f used in the present invention, is a component that imparts scratch resistance and prevents the stickiness peculiar to the elastomer. The type of the substituent to which the siloxane main chain is bonded in the molecular structure of the silicone oil is not particularly limited. Among them, dimethyl silicone oil, methylphenyl silicone oil, or alkyl-modified silicone oil is preferably used. The viscosity of the silicone oil as the component f is at least 50,000 cst, preferably at least 100,000. The viscosity of silicone oil is 50,000 cst
If it is less than 1, the initial scratch resistance and stickiness are improved, but the transfer of the molded article surface due to aging or heat becomes remarkable, which is not preferable. The amount of the component f is 0.1 to 10
%, Preferably 0.5 to 5% by weight. If the amount of the component (f) is less than 0.1% by weight, the scratch resistance and stickiness cannot be sufficiently improved. If the amount exceeds 10% by weight, the mechanical strength of the obtained composition is reduced, and the cost is further reduced. It is not preferable from the viewpoint. Also, when using this silicone oil, the dispersibility of the silicone oil should be improved,
To improve workability, it is not a problem to use a material kneaded in advance with a thermoplastic resin.

In addition to the above components (a) to (f), the composition of the present invention may 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 the inorganic filler include calcium carbonate, carbon black, talc, magnesium hydroxide, mica, barium sulfate, natural silicic acid, synthetic silicic acid (white carbon), titanium oxide, and the like. 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 10,000.
２００200,000, and the molecular weight distribution Mw /
Mn is preferably 5 or less. Further, if necessary, a nucleating agent, an outer lubricant, an inner lubricant, an ultraviolet absorber, a hindered amine light stabilizer, a hindered phenol antioxidant, a coloring agent, 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, in which a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders, Brabender, rolls and the like are used. At this time, the order of addition of each component is not limited.For example, all components are pre-mixed by a mixer such as a Henschel mixer or a blender and melt-kneaded by the above-described kneader, or any component is pre-mixed by 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 50 ° 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.

[0017]

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-1> Septon 4055 manufactured by Kuraray: having a structure of polystyrene-hydrogenated polyisoprene-polystyrene, a bound styrene content of 30% by weight and a number average molecular weight of about 170,000 <Component a-2> Asahi Kasei Kogyo Co., Ltd. H1272: 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 12
0000 (paraffin oil, Diana Process Oil PW-380 manufactured by Idemitsu Kosan Co., Ltd. [Kinematic viscosity: 381.6 cst]
(40 ° C), 30.1 (100 ° C), average molecular weight 74
6. Ring analysis value: CA = 0%, CN = 27%, CP = 73
%], 35% by weight oil extension) <Component a-3> 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 70.
000 <Component a-4> (for comparison) Septon 2007 manufactured by Kuraray: having a structure of polystyrene-hydrogenated polyisoprene-polystyrene, a bound styrene content of 30% by weight, and a number average molecular weight of about 40000 <Component b-1 > Asahi Kasei Kogyo ethylene-propylene block copolymer:
Asahi Polypropylene M7646: Melt flow rate 15dg /
min (ASTM D1238), heat deformation temperature 120 ° C
(ASTM D648 (4.6 kgf / cm ² )) <Component b-2> (for comparison) Asahi Kasei Kogyo polypropylene: Asahi Polypro M1700:
Melt flow rate 31 dg / min (ASTM D1
238), heat deformation temperature 119 ° C (ASTMD648 (4.
6kgf / ^cm 2))

<Component c> Diana Process Oil PW-380 manufactured by Idemitsu Kosan [paraffin-based process oil, kinematic viscosity: 381.6 cst (40 ° C.), 30.1 (100)
° C), average molecular weight 746, ring analysis: CA = 0%, CN =
27%, CP = 73%] <Component d> Ethylene-propylene copolymer rubber EP07P made by Japan Synthetic Rubber [propylene content: 25% by weight MF
R (230 ° C.) = 0.7 g / 10 min Tg: −38 ° C.] <Component e> 100 parts of an ethylene-propylene-ethylidene norbornene copolymer (propylene content: 28% by weight, iodine value: 15), polypropylene ( MFR: 8 g /
(10 minutes, heat distortion temperature: 115 ° C.) 40 parts of a thermoplastic elastomer dynamically vulcanized by a twin-screw kneader with 40 parts of dicumyl peroxide (organic peroxide) as a vulcanizing agent Temperature: -60 ° C or less] <Component f-1> Silicone oil KF96 manufactured by Shin-Etsu Chemical
H-100000 [silicone oil, viscosity 10000
0 cst (25 ° C) Specific gravity 0.977 (25 ° C) Refractive index 1.403 (25 ° C) Pour point -50 ° C or less] <Component f-2> (for comparison) Silicone oil KF96H-10000 manufactured by Shin-Etsu Chemical
[Straight silicone oil, viscosity 10,000 cst
(25 ° C) Specific gravity 0.975 (25 ° C) Refractive index 1.403
(25 ° C.) Pour point −50 ° C. or less]

Examples 1 to 12 and Comparative Examples 1 to 12 are shown in Table 1.
After sufficiently dry-blending the compositions having the compounding ratios shown in Nos. 1 to 4, the mixture was melt-kneaded using a twin-screw kneader under conditions such that the resin temperature was 180 to 270 ° C, and extruded into pellets.
The following evaluation was performed using this pellet. (1) Spring hardness (JIS K6301): A press sheet was prepared from the pellets and measured. (2) Appearance: A molded product of the airbag cover having a thickness of 0.5 mm at the cleaved portion of the airbag cover and a thickness of 2 to 5 mm other than the cleaved portion of the airbag cover was prepared from the pellets using an injection molding machine, and visually observed. The appearance such as flow mark and gloss was observed immediately after molding and after a high-temperature aging test at a temperature of 110 ° C. for 400 hours. Good samples were evaluated as ○, slightly poor samples as Δ, and poor samples as ×. (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, a sample having good shape retention was evaluated as ○, and a sample having deformation or the like was evaluated as ×.

(4) Deployment test: (4) -1. Normal condition: This airbag cover molded product was subjected to an environmental 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. (5) Scratch resistance test: Kanakin No. 3 cloth (JIS) having a vertical load of 100 gf on the upper surface of this airbag cover molded product and a contact area with the molded product surface of about 1 square centimeter.
According to L0803), reciprocation was performed 10 times at a reciprocation distance of 100 millimeters at 100 millimeters per second. The surface of the molded article after the test was visually observed, and those with almost no noticeable scratches were marked with “○”, those with slightly noticeable damage were marked with “△”, and defects with “x”.

The results are shown in Tables 1 and 2 as examples, and in Tables 3 and 4 as comparative examples. The numerical value of the component a-2 in the table is% by weight excluding the oil-extended oil component in the component a-2. When the component a-2 is used, the numerical value of the component c in the table is a number obtained by adding the weight% of the oil-extended oil component in the component a-2 to the weight% of the component c. From these results, the airbag cover molded from the composition obtained in the present invention has a hardness of 60 to 99 and a temperature of -40C to 90C.
It can be seen that the airbag is excellent in deployability.

[0022]

[Table 1]

[0023]

[Table 2]

[0024]

[Table 3]

[0025]

[Table 4]

[0026]

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.

Claims (3)

(57) [Claims] 1. A thermoplastic elastomer composition comprising the following components: (A) A hydrogenated 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 number average molecular weight of 50,000 or more 5
(B) a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms having a heat distortion temperature of 90 ° C. or more;
60% by weight (c) Paraffin-based oil 5 to 50% by weight (d) Glass transition point of -30 ° C among ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber The following 5-70
% By weight (f) Viscosity (JIS Z8803, 25 ° C) is 5000
Silicon oil 0.1 which is 0 centistoke or more
-10% by weight 2. A thermoplastic elastomer composition comprising the following components: (A) A hydrogenated 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 number average molecular weight of 50,000 or more 5
(B) a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms having a heat distortion temperature of 90 ° C. or more;
60% by weight (c) Paraffin oil 5-50% by weight (e) A blend of a dynamically vulcanized ethylene-α-olefin copolymer rubber and a polyolefin resin, or
An embrittlement temperature of a thermoplastic elastomer composed of a blend of a dynamically vulcanized ethylene-α-olefin-nonconjugated diene copolymer rubber and a polyolefin-based resin has a brittle temperature of -50
5 ° C to 70% by weight (f) Viscosity (JIS Z8803, 25 ° C) is 5000
Silicon oil 0.1 which is 0 centistoke or more
-10% by weight 3. A thermoplastic elastomer composition comprising the following components: (A) A hydrogenated 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 number average molecular weight of 50,000 or more 5
(B) a copolymer of propylene and an α-olefin having 2 to 8 carbon atoms having a heat distortion temperature of 90 ° C. or more;
60% by weight (c) Paraffin-based oil 5 to 50% by weight (d) Glass transition point of -30 ° C among ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber Or (e) a blend of a dynamically vulcanized ethylene-α-olefin copolymer rubber and a polyolefin resin, or
An embrittlement temperature of a thermoplastic elastomer composed of a blend of a dynamically vulcanized ethylene-α-olefin-nonconjugated diene copolymer rubber and a polyolefin-based resin has a brittle temperature of -50
(D) + (e): 5 to 70% by weight (f) Viscosity (JIS Z8803, 25 ° C.): 5000
Silicon oil 0.1 which is 0 centistoke or more
-10% by weight