JPH08319383A - Thermoplastic elastomer composition - Google Patents

Abstract

PURPOSE: To obtain a thermoplastic elastomer composition, comprising a specific hydrogenated block copolymer, a specified olefin copolymer, a specific copolymer and an oil, excellent in air bag inflating properties, high-temperature aging and weather resistances, molding processability, low cost properties, etc., and useful for automotive air bag covers. CONSTITUTION: This thermoplastic elastomer composition comprises (A) 5-50wt.% block copolymer, comprising >=2 terminal polymer blocks consisting essentially of a vinyl aromatic compound and an intermediate polymer block consisting essentially of a conjugated diene compound and having >=50000 number-average molecular weight, (B) 20-60wt.% propylene-2-8C α-olefin copolymer having >=90 deg.C heat distortion temperature, (C) 5-70wt.% ethylene-α-olefin(- conjugated diene) copolymer rubber having <=-30 deg.C glass transition temperature, (D) 5-50wt.% paraffinic oil and (E) 0.1-10wt.% silicone oil having >=50000cSt viscosity (at 25 deg.C according to JIS Z8803).

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 deployability of the airbag and resistance to scattering at the time of deployment, and which does not require painting. The present invention relates to an elastomer composition.

[0002]

2. Description of the Prior Art Conventionally, an airbag cover is made of urethane with a reinforcing nylon net inside, and there is no reinforcing nylon net due to the expansion and deployment of an airbag folded and stored inside. It is designed to burst at the thin wall. However, when such a airbag cover does not use a reinforcing nylon-based net, a problem such as cracking other than the thin-walled cleavage portion or scattering of the cover occurs at the time of rupture, and the reinforcing nylon-based net is used. In this case, although the problem of tearability at the time of deploying the airbag is solved, it takes time to align the reinforcing net when forming the airbag cover, and the defect rate due to the positional deviation of the reinforcing nylon net increases. Alternatively, there is a drawback that productivity is lowered because of urethane RIM molding.

Further, many studies have been made on airbag covers made of a thermoplastic resin which does not require a reinforcing nylon net. However, these are used as automobile interior parts having a hardness of 60 to 99, which are soft enough for humans not to feel uncomfortable. The airbag surely expands at a temperature of -40 ° C to 90 ° C,
It was very difficult for the airbag cover to have cracks other than the split portion when the airbag was deployed, and for the fragments to never fly. Among them, in some polyolefin-based thermoplastic resins, the temperature immediately after molding is -40 ° C to 9 ° C.
Although it has a good spreading performance at 0 ° C, the high temperature aging test and the weather resistance test are performed due to the change of the physical properties accompanying the change of the phase structure such as the change of the crystallinity of the polyolefin thermoplastic resin after the high temperature aging test or the weather resistance test. After the property test, the deployability of the airbag at a temperature of -40 ° C to 90 ° C and the scattering resistance at the time of deployment cannot be satisfied. As described above, at present, an airbag cover having a hardness of 60 to 99, which has 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 the air bag covers currently under study are painted in order to suppress unpleasant sensations such as scratches due to nails and clothes, stickiness, and discoloration due to sunlight.・ Airbag covers that do not require painting have been demanded from the viewpoint of economy. To improve scratch resistance or suppress stickiness, 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 increase the surface slipperiness of molded products. Attempts have been made to improve it. However, since these materials remarkably migrate to the surface with the passage of time or heat, there is a problem that the appearance of the molded product is impaired or the scratch resistance is lowered.

[0005]

SUMMARY OF THE INVENTION The present invention solves the above-mentioned problems of the prior art and provides a urethane-coated article containing a reinforcing nylon net in an airbag cover of an airbag system used as a safety device for automobiles and the like. JIS that does not require nylon net for reinforcement that could not be done
Another 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 researches, the present inventors have found that among styrene elastomers known as a-component hydrogenated block copolymers, particularly those having a number average molecular weight of 50,000 or more. As a main component, a copolymer rubber of component d or a thermoplastic elastomer of component e is added and alloyed to improve the developing performance on the low temperature side,
Improve the development performance on the high temperature side by adding and alloying the copolymer of propylene of the b component and α-olefin having 2 to 8 carbon atoms, and use the silicone oil having the viscosity of the f component of 50,000 centistokes or more. With a compounding design concept of improving scratch resistance and stickiness, -40
It is possible to obtain an airbag cover that has excellent deployability in a wide temperature range of 90 ° C to 90 ° C, and resistance to scattering during deployment, and with an optimal combination of these, not only immediately after molding but also in a high temperature aging test and weather resistance test. After that, it was found that in a wide temperature range of −40 ° C. to 90 ° C., an air bag cover having excellent deployability and scatter resistance during deployment, which does not require painting, is obtained.
The present invention has been completed.

That is, the present invention provides the following components a, b, and
c, d, f or components a, b, c, e, f, and further components a, b, c, d + e, f are melt-kneaded into pellets and are suitable for high temperature and low temperature deployment. A thermoplastic elastomer composition is provided. (A) by hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly containing vinyl aromatic compounds and intermediate polymer blocks B mainly containing at least one conjugated diene compound The resulting hydrogenated block copolymer having a number average molecular weight of 50,000 or more 5
˜50 wt% (b) A copolymer having a heat distortion temperature of 90 ° C. or higher among propylene and an α-olefin having 2 to 8 carbon atoms 20 to
60 wt% (c) Paraffin oil 5 to 50 wt% (d) Ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C. The following (e) a blend of a dynamically vulcanized ethylene-α-olefin copolymer rubber and a polyolefin resin, or
Among the thermoplastic elastomers comprising a blend of dynamically vulcanized ethylene-α-olefin-non-conjugated diene copolymer rubber and polyolefin resin, the brittleness temperature is -50.
℃ or less, (d) and / or (e) 5 to 70
Weight% (f) Viscosity (JIS Z8803, 25 ° C) is 5000
0.1 to 10% by weight of silicone oil, which is 0 centistokes (hereinafter abbreviated as cst) or more

[0008]

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described in detail below. The hydrogenated block copolymer used in the present invention comprises a terminal polymer block A mainly composed of at least two vinyl aromatic compounds and an intermediate polymer block B mainly composed of at least one conjugated diene compound. Is obtained by hydrogenating the following block copolymer, and is a hydrogenated vinyl aromatic compound-conjugated diene compound block copolymer having a structure represented by the following general formula. A- (BA) n (1≤n≤5) This hydrogenated block copolymer has a hardness of 99 or less, preferably 90 or less, and contains 5 to 50 vinyl aromatic compounds.
%, Preferably 10 to 40% by weight, and referring to the block structure, the vinyl aromatic compound-based terminal polymer A comprises a vinyl aromatic compound polymer block or a vinyl aromatic compound of 50% by weight. Having a structure of a copolymer block of a vinyl aromatic compound and a hydrogenated conjugated diene compound, the content of which exceeds 70% by weight, and which is mainly composed of 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 hydrogenated conjugated diene compound 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 containing a vinyl aromatic compound and polymer blocks mainly containing a hydrogenated conjugated diene compound, each polymer block may have the same structure or different. It may be a structure.

As the vinyl aromatic compound constituting the hydrogenated block copolymer, for example, one kind or two or more kinds can be selected from styrene, α-methylstyrene, vinyltoluene, p-tert-butylstyrene and the like. Of these, styrene is preferable. As the conjugated diene compound before hydrogenation constituting the hydrogenated conjugated diene compound, for example, one kind or two or more kinds are selected from butadiene, isoprene, 2.3-dimethyl-1.3-butadiene and the like. Among them, butadiene, isoprene and combinations 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 50.
000 or more, preferably 90,000 to 200,000, and 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,
It cannot give sufficient heat resistance. When 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. If the content of the component a is less than 5% by weight, sufficient strength or impact resistance cannot be imparted at both high temperature and low temperature, and if it exceeds 50% by weight, the fluidity is remarkably reduced and after molding. A molded product with a good appearance cannot be obtained. Further, since the hydrogenated block copolymer of the component a has a large number average molecular weight, it is necessary to improve workability.
An oil-extended product of a paraffinic oil of component c described later can be used as appropriate.

Next, it is effective for improving the processability and heat resistance of the copolymer of propylene used as the component b of the present invention and the α-olefin having 2 to 8 carbon atoms, and the resulting 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- Examples thereof include polybutene-1 and the like. 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, it is preferable to add a nucleating agent in order to suppress changes in physical properties in the high temperature aging test and the weather resistance test. The melt flow rate (ASTM-D-1238L condition, 230 ° C.) of the copolymer of propylene and α-olefin having 2 to 8 carbon atoms is 0.1 to 60 g / 10 min, especially 0.5.
Those in the range of up to 50 g / 10 min can be preferably used. If the melt flow rate is less than 0.1 g / 10 min, the fluidity at the time of molding deteriorates, and if it exceeds 60 g / 10 min, the heat resistance decreases, which is not preferable. In addition, the heat distortion temperature (JIS K7207 4.6 kgf / cm ² ) is limited to 90 ° C. or higher here because if it is lower than that, there is no effect in improving heat resistance. The blending amount of the component b is 20 to 60
%, Preferably 30 to 50% by weight. b
When the content of the components is less than 20% by weight, sufficient heat resistance cannot be imparted, and when it exceeds 60% by weight, the impact resistance at low temperature is remarkably reduced, and therefore the airbag cover at -40 ° C. Good deployment performance cannot be exhibited during deployment.

The c-component paraffinic oil used in the present invention is an essential component having a function of adjusting the hardness of the resulting composition and giving flexibility. Generally, softening, increasing volume of rubber,
The process oil or extender oil used for improving processability is a mixture of mineral oil rubber softeners, which is an aromatic ring, a naphthene ring, and a paraffin chain. 50% of the number
Those occupying the above are called paraffin type, those having 30 to 45% of naphthene ring carbon atoms are naphthene type, and those having more than 30% of aromatic ring carbon atoms are aromatic type. The oil used as the component c of the present invention is a paraffinic oil in the above category, and naphthene-based and aromatic oils are not preferable in terms of dispersibility and solubility. The paraffinic rubber softener has a kinematic viscosity of 20 to 50 at 37.8 ° C.
0 cst, pour point -10 to -15 ℃ and flash point 17
Indicates 0 to 300 ° C. The content of the paraffinic oil as the component c is 5 to 50% by weight, preferably 10 to 30% by weight. When the content of the component c is less than 5% by weight, the resulting composition is close to a resin composition, which increases hardness, loses flexibility, and is not preferable from an economical point of view. When the content of the component c exceeds 50% by weight, bleeding out of the softening agent is likely to occur, and tackiness may occur in the final product, which lowers mechanical properties and is not preferable.

Further, the copolymer rubber used as the component d of the present invention is an essential component for improving the air bag deployability at -40 ° C. The α-olefin having 3 to 15 carbon atoms is suitable for the ethylene-α-olefin copolymer rubber and / or the ethylene-α-olefin-non-conjugated diene copolymer rubber. 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, so-called EPR and EPDM are used as the d component.
Is preferred. The ethylene / α · olefin ratio of the copolymer rubber is 50/50 to 90/10 by weight, and more preferably 60/40 to 80/20. Here, the glass transition point is defined to be -30 ° C or lower because those having a glass transition point higher than -30 ° C cannot improve the airbag deployability at -40 ° C. The amount of component d is 5 to 7
It can be selected in the range of 0% by weight, preferably 10 to 6
It is 5% by weight. When the amount of the component d is less than 5% by weight, improvement of the air bag deployability at −40 ° C. as an effect of adding the copolymer rubber is not recognized, which is not preferable. When the amount of the component d exceeds 70% by weight, the strength of the obtained elastomeric composition cannot be maintained at high temperature, the airbag deployability at 90 ° C is not preferable, and the heat-resistant shape retention property at high temperature is significantly deteriorated. It cannot be used as a molded product.

The thermoplastic elastomer used as the component e of the present invention is a component for improving the air bag deployability 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, as the ethylene-α-olefin-non-conjugated diene copolymer rubber in the component e, so-called EP is used.
DM is preferred. The ethylene / α-olefin ratio of the copolymer rubber is 50/50 to 90/10 by weight, and more preferably 60/40 to 80/20. As the vulcanizing agent, a general vulcanizing agent for rubber can be used, and in addition to sulfur, an alkylphenol / formaldehyde resin and an organic peroxide such as dicumyl peroxide are particularly preferably used. In addition to the vulcanizing agent, a vulcanization aid, an antioxidant, etc. may be used in combination. The addition amount of the alkylphenol / formaldehyde resin was 0. 0 with respect to 100 parts by weight of the copolymer rubber.
The range of 5 to 15 parts by weight is preferable from the viewpoint of the balance between strength and workability. In the case of organic peroxide, copolymer rubber 100
The range of 0.05 parts by weight to 1 part by weight with respect to parts by weight is preferable in terms of balance between strength and workability. Copolymer rubber 10
It is indispensable to contain 5 parts by weight or more of a polyolefin resin with respect to 0 parts by weight in order to maintain the processability. While dynamically melting and kneading the blend of the copolymer rubber and the polyolefin resin, the vulcanizing agent is added and vulcanized to obtain the component e.
Can be obtained. The reason why the embrittlement temperature of the thermoplastic elastomer is specified to be -50 ° C or lower is that those having an embrittlement temperature higher than that cannot improve the airbag deployability at -40 ° C. The compounding amount of the e component can be selected in the range of 5 to 70% by weight, preferably 10 to 65% by weight. When the content of the component e is less than 5% by weight, improvement of the airbag deployability at −40 ° C. as an effect of adding the copolymer rubber is not recognized, which is not preferable. If the content of the e component exceeds 70% by weight, the strength of the obtained elastomeric composition cannot be maintained at high temperatures, the airbag deployability at 90 ° C. is not preferable, and the heat-resistant shape retention at high temperatures is significantly deteriorated. It cannot be used as a molded product. Further, the d component and the e component may be mixed and used. In that case, the total amount of both components added is within the range of 5 to 70% by weight.

The silicone oil which is the f component used in the present invention is a component which imparts scratch resistance and prevents stickiness peculiar to the elastomer. The kind of the substituent bonded to the siloxane main chain in the molecular structure of this silicone oil is not particularly limited, but among them, dimethyl silicone oil, methylphenyl silicone oil, or alkyl-modified silicone oil is preferably used. The viscosity of the silicone oil which is the f component is 50,000 cst or more, preferably 100,000 or more. The viscosity of silicone oil is 50,000 cst
If it is less than the above range, the initial scratch resistance and stickiness are improved, but migration of the surface of the molded product due to aging or heat is remarkable, which is not preferable. The amount of the component f is 0.1 to 10
% By weight, preferably 0.5-5% by weight. If the content of the f component is less than 0.1% by weight, scratch resistance and stickiness cannot be sufficiently improved, and if it exceeds 10% by weight, the mechanical strength of the obtained composition is lowered, and further economical It is not preferable from the aspect. When using this silicone oil, improve the dispersibility of the silicone oil,
To improve workability, it is possible to use a material which is 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 the product cost as an extender, but also have a positive effect on quality improvement (inorganic filler: heat-resistant shape retention, flame retardancy, etc., polystyrene resin: processability improvement, etc.). There is also an advantage. 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, and carbon black includes channel black, Furnace black etc. can be used. Among these inorganic fillers, talc and calcium carbonate are economically advantageous and preferable. Further, as the polystyrene resin which can be used for this purpose, those obtained by a radical polymerization method or an ionic polymerization method can be preferably used, and the number average molecular weight thereof is 5,000 to 500,000, preferably 10,000.
Can be selected from the range of up to 200,000, and the molecular weight distribution Mw /
Mn is preferably 5 or less. Further, if necessary, a nucleating agent, an external lubricant, an internal lubricant, an ultraviolet absorber, a hindered amine light stabilizer, a hindered phenol antioxidant, a colorant 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 adopted. Basically, it is a mechanical melt-kneading method, and a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders, brabenders, rolls and the like are used for these. At this time, the addition order of each component is not limited, for example, all components are premixed by a mixer such as a Henschel mixer and a blender and melt-kneaded by the above kneader, or any components are premixed to form a masterbatch. It is possible to employ an addition method in which the components are melt-kneaded, and then the remaining components are added and melt-kneaded. Further, at this time, the temperature for melt kneading is 1
It can be suitably selected from 50 ° C to 300 ° C. The hydrogenated block copolymer composition obtained here can be further supplied to an injection molding machine equipped with a mold for an airbag cover, and injection molded in a short time to obtain an airbag cover. Further, since the composition of the present invention is thermoplastic, the unnecessary burr, runner portion, and spool portion of the injection-molded product can be recycled and can be reused as a material for an airbag cover.

[0017]

The present invention will be described in more detail with reference to the following examples, but the present invention is not limited to these examples. The components blended in the examples and comparative examples shown below are as follows. <Component a-1> Kuraray Septon 4055: having a structure of polystyrene-hydrogenated polyisoprene-polystyrene, bound styrene amount of 30% by weight, number average molecular weight of about 170,000 <component a-2> Asahi Kasei Kogyo Tuftec H1272: polystyrene-hydrogenated polybutadiene-polystyrene structure, bound styrene content 35% by weight, number average molecular weight about 12
0000 (paraffin oil, Diana Process Oil PW-380 manufactured by Idemitsu Kosan [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 wt% oil-extended product) <Component a-3> Asahi Kasei Kogyo Tuftec H1071: polystyrene-hydrogenated polybutadiene-polystyrene structure, bound styrene amount 20% by weight, number average molecular weight about 70.
000 <Component a-4> (for comparison) Septon 2007 manufactured by Kuraray Co., Ltd .: having a structure of polystyrene-hydrogenated polyisoprene-polystyrene, the amount of bound styrene is 30% by weight, and the number average molecular weight is about 40,000 <Component b-1. ＞ Asahi Kasei Corporation ethylene-propylene block copolymer:
Asahi Polypro M7646: Melt flow rate 15 dg /
min (ASTM D1238), heat distortion temperature 120 ° C
(ASTM D648 (4.6 kgf / cm ² )) <Component b-2> (for comparison) Polypropylene manufactured by Asahi Kasei: Asahi Polypro M1700:
Melt flow rate 31 dg / min (ASTM D1
238), heat distortion temperature 119 ° C. (ASTM D648 (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)
℃), average molecular weight 746, ring analysis value: CA = 0%, CN =
27%, CP = 73%] <Component d> Ethylene-propylene copolymer rubber EP07P manufactured 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 ethylene-propylene-ethylidene norbornene copolymer (propylene content: 28% by weight, iodine value: 15), polypropylene ( MFR: 8g /
10 minutes, heat distortion temperature: 115 ° C.) 40 parts and dicumyl peroxide (organic peroxide) 0.5 part as a vulcanizing agent were dynamically vulcanized by a biaxial kneader to produce a thermoplastic elastomer [embrittlement] Temperature: -60 ° C or less] <Component f-1> Silicon oil KF96 manufactured by Shin-Etsu Chemical
H-100,000 [silicone oil, viscosity 10,000
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) Silicon 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 lower]

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 Tables 4 to 4, they were melt-kneaded and extruded into pellets by using a twin-screw kneader under the condition that the resin temperature was 180 to 270 ° C.
The following evaluation was performed using this pellet. (1) Spring hardness (JIS K6301): A press sheet was prepared from this pellet and measured. (2) Appearance: An injection molding machine was used to make a molded product of an 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 from the pellets and visually inspected. The appearance of flow marks, luster, etc. was observed immediately after molding and after a high temperature aging test at a temperature of 110 ° C. for 400 hours. Good ones were evaluated as ◯, somewhat poor ones as Δ, and poor ones as x. (3) Heat-resisting shape retention: This airbag cover molded product has a temperature of 1
A heat and shape retention test was conducted in an environment of 10 ° C. After 24 hours, the sample having good shape retention was evaluated as ◯, and the sample having deformation was evaluated as x.

(4) Deployment test: (4) -1. Normal condition: This air bag cover molded product is subjected to an ambient temperature of 9
An airbag deployment test was performed at 0 ° C, 23 ° C and -40 ° C. A sample that developed better than the cleaved part of the airbag cover was evaluated as ◯, and a sample that cracked other than the cleaved part of the airbag cover, the cover scatters, or the airbag that did not expand well was evaluated as x. (4) -2. After high temperature aging test: This airbag cover molded product was subjected to a high temperature aging test in an environment of a temperature of 110 ° C. After high temperature aging test for 400 hours, environmental temperature 90 ℃, 23 ℃ and -4
An airbag deployment test was performed at 0 ° C. A sample that developed better than the cleaved part of the airbag cover was evaluated as ◯, and a sample that cracked other than the cleaved part of the airbag cover, the cover scatters, or the airbag that did not expand well was evaluated as x. (5) Scratch resistance test: The upper surface of this air bag cover molded product has a vertical load of 100 gf and the contact area with the surface of the molded product is about 1 cm 2 (Kanakin 3 cloth (JIS
According to L0803), a round trip distance of 100 millimeters was repeated 10 times at 100 millimeters per second. After the test, the surface of the molded article was visually observed, and those with almost no scratches were marked with ◯, those with some noticeable scratches were marked with Δ, and defects were marked with x.

The results are shown in Tables 1 and 2 as examples, and in Tables 3 and 4 as comparative examples. In addition, 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 the number of parts 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 formed by molding the composition obtained in the present invention has a hardness of 60 to 99 and a temperature of -40 ° C to 90 ° C.
It can be seen that the airbag has excellent 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 good expansion of the airbag without cracks or scattering of the cover other than the cleavage portion when the airbag is expanded at -40 ° C to 90 ° C. Is obtained. Also, it has excellent long-term reliability such as high temperature aging resistance and weather resistance. In addition, compared to conventional urethane and nylon net for reinforcement, it has excellent molding processability, good productivity, easy color matching, low cost, and so on, its utility value is very large.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification code Internal reference number FI Technical display location C08L 23/08 C08L 23/08 23/26 LDA 23/26 LDA 53/02 LCN 53/02 LCN LCQ LCQ LLY LLY 83/04 LRT 83/04 LRT LRY LRY

Claims (3)

[Claims] 1. A thermoplastic elastomer composition comprising the following components. (A) by hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly containing vinyl aromatic compounds and intermediate polymer blocks B mainly containing at least one conjugated diene compound The resulting hydrogenated block copolymer having a number average molecular weight of 50,000 or more 5
˜50 wt% (b) A copolymer having a heat distortion temperature of 90 ° C. or higher among propylene and an α-olefin having 2 to 8 carbon atoms 20 to
60 wt% (c) Paraffin oil 5 to 50 wt% (d) Ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C. The following 5-70
Weight% (f) Viscosity (JIS Z8803, 25 ° C) is 5000
Silicone oil 0.1 which is more than 0 centistokes
-10% by weight 2. A thermoplastic elastomer composition comprising the following components. (A) by hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly containing vinyl aromatic compounds and intermediate polymer blocks B mainly containing at least one conjugated diene compound The resulting hydrogenated block copolymer having a number average molecular weight of 50,000 or more 5
˜50 wt% (b) A copolymer having a heat distortion temperature of 90 ° C. or higher among propylene and an α-olefin having 2 to 8 carbon atoms 20 to
60% by weight (c) Paraffin oil 5 to 50% by weight (e) Blend of dynamically vulcanized ethylene-α / olefin copolymer rubber and polyolefin resin, or
Among the thermoplastic elastomers comprising a blend of dynamically vulcanized ethylene-α-olefin-non-conjugated diene copolymer rubber and polyolefin resin, the brittleness temperature is -50.
5 ° C to 70% by weight (f) Viscosity (JIS Z8803, 25 ° C) is 5000
Silicone oil 0.1 which is more than 0 centistokes
-10% by weight 3. A thermoplastic elastomer composition comprising the following components. (A) by hydrogenating a block copolymer comprising at least two terminal polymer blocks A mainly containing vinyl aromatic compounds and intermediate polymer blocks B mainly containing at least one conjugated diene compound The resulting hydrogenated block copolymer having a number average molecular weight of 50,000 or more 5
˜50 wt% (b) A copolymer having a heat distortion temperature of 90 ° C. or higher among propylene and an α-olefin having 2 to 8 carbon atoms 20 to
60 wt% (c) Paraffin oil 5 to 50 wt% (d) Ethylene-α-olefin copolymer rubber and / or ethylene-α-olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C. And (e) a blend of a dynamically vulcanized ethylene-α-olefin copolymer rubber and a polyolefin resin, or
Among the thermoplastic elastomers comprising a blend of dynamically vulcanized ethylene-α-olefin-non-conjugated diene copolymer rubber and polyolefin resin, the brittleness temperature is -50.
5 to 70% by weight of (d) + (e) (f) Viscosity (JIS Z8803, 25 ° C.) of 5,000 or less
Silicone oil 0.1 which is more than 0 centistokes
-10% by weight