JPH06116474A - Hydrogenated block copolymer elastomer composition - Google Patents

Abstract

PURPOSE:To obtain an elastomer composition of improved dusting resistance by mixing a specified hydrogenated block copolymer with a paraffinic oil, a crystalline olefin resin blend and an ethylene/alpha-olefin copolymer rubber. CONSTITUTION:The composition comprises 100 pts.wt. hydrogenated block copolymer of a spring hardness of 99 or below, prepared by hydrogenating a block copolymer composed of at least two terminal polymer blocks based on a vinylaromatic compound and at least one intermediate polymer block based on a conjugated diene compound, 10-300 pts.wt. paraffinic oil, 5-250 pts.wt. amorphous olefin resin or blend thereof with a crystalline olefin resin of a heat distortion temperature of 90 deg.C or above in a weight ratio of 25/75, and 5-100 pts.wt. ethylene/alpha-olefin copolymer rubber or ethylene/alpha-olefin/ nonconjugated diene terpolymer rubber of a glass transition temperature of -30 deg.C or below.

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 excellent in the deployability of the airbag and the anti-scattering property when deployed 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, urethane having a reinforcing nylon net is used for an airbag cover. The airbag cover is designed to rupture at a thin portion without a reinforcing nylon net when the airbag folded and stored inside is expanded and deployed. However, in such an airbag cover, a crack is generated in a portion other than the thin-walled cleavage portion or the cover is scattered unless a reinforcing nylon net is used. In addition, it takes time to position the reinforcing net when forming the airbag cover, and the defective rate due to the positional deviation of the reinforcing nylon net is high. The disadvantage was the low production of urethane RIM. In addition, many studies were made on airbag covers made of a thermoplastic resin that does not require a reinforcing nylon net, but the softness that humans do not feel uncomfortable as automobile interior parts with hardness of 40 to 90 and temperature of -40 to 85 ° C. In the airbag at a temperature of -40 ° C to 90 ° C, it is very difficult to surely deploy the airbag at Hardness of 40 to 40
At present, the 90 airbag cover has not been developed.

[0003]

DISCLOSURE OF THE INVENTION The present invention is a JISK630 made of a thermoplastic resin that does not require a nylon net for reinforcement, which was not possible with an airbag cover of an airbag system used as a conventional safety device for automobiles and the like.
As a result of studying to obtain an airbag cover having a spring hardness (hardness) of 40 to 90 of No. 1, a hydrogenated block copolymer composition was used as a main component, and a low temperature side developability was a copolymer of d component. It is improved by adding alloying a thermoplastic elastomer of rubber or e component, and the developability at high temperature side is improved by adding alloying of amorphous olefin resin of c component. ℃
It is possible to obtain an airbag cover which is excellent in deployability of the airbag in a particularly wide temperature range of up to 85 ° C. and resistance to scattering at the time of deployment, and based on this finding, various studies are advanced to complete the present invention. It has come.

[0004]

That is, the present invention relates to a hydrogenation block for an airbag cover, which is obtained by melt kneading components a, b, c, d or components a, b, c, e described below into pellets. It is a polymer elastomer composition. (A) Hydrogenation of a block copolymer consisting of at least two terminal polymer blocks A mainly composed of vinyl aromatic compounds and at least one intermediate polymer block B mainly composed of conjugated diene compounds Obtained hydrogenated block copolymer having a spring hardness (JIS K6301) of 99 or less 100 parts by weight (b) Paraffin oil 10 to 300 parts by weight (c) Amorphous olefin resin alone or amorphous olefin A blend of a base resin and a crystalline olefin resin having a heat distortion temperature of 90 ° C. or higher with a ratio of 25/75 or higher (weight) 5 to 250 parts by weight (d) ethylene-α / olefin copolymer rubber and Or 5 to 100 parts by weight of ethylene-α-olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C or lower (e) dynamically vulcanized Ren-.alpha. · olefin - non-conjugated diene copolymer rubber and a polyolefin thermoplastic elastomer sac Chi brittle temperature comprises a blend of the resin include the -50 ° C. or less 10 to 150 parts by weight

The hydrogenated block copolymer used in the present invention is a terminal polymer block A mainly containing at least two vinyl aromatic compounds and an intermediate polymer block mainly containing at least one conjugated diene compound. A vinyl aromatic compound having a structure represented by the following general formula, which is obtained by hydrogenating a block copolymer composed of B and
It is a hydrogenated product of a conjugated diene compound block copolymer. A- (BA) n 1 ≦ n ≦ 5 This hydrogenated block copolymer has a hardness of 99 or less, preferably 90 or less in order to obtain a hydrogenated block copolymer elastomer composition. It is necessary to contain the vinyl aromatic compound in an amount of 5 to 50% by weight, preferably 10 to 40% by weight. Further, referring to the block structure, the terminal polymer A mainly composed of the vinyl aromatic compound is a vinyl aromatic compound. Having a structure of a 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, and In addition, the intermediate polymer block B mainly composed of a hydrogenated conjugated diene compound is a hydrogenated conjugated diene compound polymer block or a hydrogenated copolymer block. The diene compound preferably exceed 50% by weight and has a structure of a copolymer block of a conjugated diene compound and a vinyl aromatic compound added hydrogen containing more than 70 wt%.
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, etc., 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. The number average molecular weight (Mn) of the hydrogenated block copolymer used in the present invention is 5,000 to 1,000,000, preferably 10,000 to 800,000, and further preferably 3
The molecular weight distribution Mw is in the range of 0000 to 500000
/ Mn is 10 or less (Mw: weight average molecular weight). Further, the molecular structure of the hydrogenated block copolymer may be linear, branched, radial or any combination thereof. Furthermore, the dynamic storage elastic modulus G ′ at 23 ° C. of the hydrogenated block copolymer of the above type is 5 × 10 ² MPa or less.

The paraffinic oil of the component b used in the present invention is an essential component which has a function of adjusting the hardness of the composition obtained and giving flexibility. Generally, softening, increasing volume of rubber,
The process oil or extender oil, which is used to improve processability, is a mixture of mineral oil-based rubber softeners for aromatic oils, naphthene rings and paraffin chains. Those which occupy 50% or more of the number are called paraffinic, those whose naphthene ring carbon number is 30 to 45% are naphthenic, and those whose aromatic ring carbon number exceeds 30% are aromatic. The oil used as the component b of the present invention is preferably a paraffinic oil in the above category, and a naphthene-based or aromatic oil is 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 1
70 to 300 ° C is shown. The blending amount of the paraffinic oil of the component b is 100 of the component a.
The amount is 10 to 300 parts by weight, preferably 20 to 250 parts by weight, relative to the parts by weight. If the content is more than 300 parts by weight, bleeding-out of the softening agent is likely to occur, stickiness may occur in the final product, and mechanical properties may be deteriorated. In addition, if the amount is less than 10 parts, the resulting composition becomes closer to the resin composition, the hardness increases, the flexibility is lost, and it is not preferable from the economical viewpoint.

Next, the amorphous olefin resin used as the component c of the present invention is not only an essential component for improving the air bag deployability at 85 ° C., but also the composition obtained. It is effective for improving processability and heat resistance, and is a polymer having a cyclic olefin structure alone or a copolymer of a cyclic olefin and an α-olefin, and can be said to be an amorphous polyolefin because of its structure and properties. Examples of the amorphous olefin resin include the following.
For example, a ring-opening polymer of dicyclopentadiene represented by the general formula (1) or a hydrogenated product thereof.

[0009]

[Chemical 1]

This ring-opening polymer can be produced by a known ring-opening polymerization method for cyclic olefins using dicyclopentadiene as a monomer. Further, the hydrogenated product of this ring-opening polymer can also be obtained by utilizing a usual hydrogenation reaction method. Also, at least one compound selected from the group consisting of unsaturated monomers represented by the general formula (2) or the general formula (3), and the like. These are easily manufactured by condensing cyclopentadiene and corresponding olefins, and cyclic olefins by the Diels-Alder reaction.

[0011]

[Chemical 2]

[0012]

[Chemical 3]

(Wherein n and m are both 0 or a positive integer, l is an integer of 3 or more, and R ₁ to R
₁₀ is a hydrogen atom, a halogen atom or a carbon hydrogen group, respectively. And (5) (R _{3 to} R ₆ ), and general formula (4) (in the formula, R ₁ represents a hydrogen atom or a methyl group, and R ₂ represents a C _{1 to} C ₂₀ hydrocarbon group). is a hydrogen atom or R _3, the R ₄ indicates an alkylidene group consisting C ₁ -C _10.) ring-opening polymerization of tetracyclododecene derivative represented by the body or its hydrogenated product, and the like. In addition, these can also be used as a mixture of 2 or more types.

[0014]

[Chemical 4]

[0015]

[Chemical 5]

The blending amount of component c is 5 to 250 parts by weight, preferably 10 to 150 parts by weight, relative to 100 parts by weight of component a.
Parts by weight. If the amount is more than 250 parts by weight, the hardness of the resulting elastomer composition becomes too high and the flexibility is lost, so that a product having a rubber-like feel cannot be obtained, and the rubber elasticity (compression set) at high temperature is not obtained. ) Is extremely worse,
The air bag deployability at 85 ° C is not preferable. Also, 5
If the amount of the component (c) is less than 85 parts by weight,
It can only exhibit airbag deployability at ℃, processability, and heat resistance. The amorphous olefin-based resin and crystalline olefin-based resin of the above-mentioned component c can be used in combination as the component c. The crystalline olefin resin used is, for example, polyethylene, isotactic polypropylene or a random or block copolymer of propylene and a small amount of other α-olefin, specifically polypropylene-.
Examples thereof include ethylene copolymers, propylene-1-hexene copolymers, propylene-4-methyl-1pentene copolymers, poly-4-methyl-1-pentene, and polybutene-1. Further, it is effective to use a cyclic olefin resin. Further, two or more crystalline olefin resins such as polyethylene and polypropylene may be used in combination. MFR (ASTM-D-1238L condition, when isotactic polypropylene or its copolymer is used as the crystalline olefin resin,
230 ° C) is 0.1 to 50 g / 10 minutes, especially 0.5 to 30 g
Those having a range of / 10 minutes can be preferably used. Further, the reason why the heat distortion temperature (JIS K72074.6 kgf / cm ² ) is limited to 90 ° C. or higher here is that if it is lower than that, there is no effect in improving heat resistance. When the component c is a blend of an amorphous olefin resin and a crystalline olefin resin having a heat distortion temperature of 90 ° C. or higher, the ratio is specified to be 25/75 or more (by weight). This is because, in the case of, the effect of adding the amorphous olefin resin (improvement of air bag deployability at 85 ° C.) is not exhibited.

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 e 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 that cannot improve the airbag deployability at -40 ° C. The blending amount of component d can be suitably selected within the range of 5 to 100 parts by weight with respect to 100 parts by weight of component a. When the content of the component e exceeds 100 parts by weight, the elastomeric composition obtained is inferior in rubber elasticity at high temperature and the airbag deployability at 85 ° C. is not preferable, and the heat-resistant shape retention property at high temperature is remarkably deteriorated. It cannot be used as a product. Further, when the content of the component d is less than 5 parts by weight, the improvement of the airbag deployability at −40 ° C. as an effect of adding the copolymer rubber is not recognized, which is not preferable.

Further, the thermoplastic elastomer used as the component e of the present invention is an essential component for improving the air bag deployability at -40 ° C, and the α-olefin in the copolymer rubber has 3 to 15 carbon atoms. The ones are 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, ethylene-
So-called EPDM is suitable as the α-olefin-non-conjugated diene copolymer rubber. Copolymer rubber ethylene /
The α / olefin ratio is 50/50 to 90/10 by weight,
More preferably, 60/40 to 80/20 is suitable. 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 is preferably 0.5 part to 15 parts by weight with respect to 100 parts by weight of the copolymer rubber in terms of the balance between strength and processability. In the case of an organic peroxide, the range of 0.05 parts by weight to 1 part by weight is preferable with respect to 100 parts by weight of the copolymer rubber in terms of the balance between strength and processability. In order to maintain processability, it is necessary to include 5 parts by weight or more of a polyolefin resin with respect to 100 parts by weight of the copolymer rubber. This component f can be obtained by dynamically vulcanizing by adding a vulcanizing agent while dynamically melting and kneading the blend of the copolymer rubber and the polyolefin resin. As a method of obtaining the e component, there is a method of obtaining a commercially available product. However, since the b component of the present invention may be added in advance in order to improve the processability in these methods, the addition amount of the b component is Correction is necessary.
Here, the embrittlement temperature of the thermoplastic elastomer is specified to be -50 ° C or less, and that of the one having an embrittlement temperature higher than that is -4.
This is because the air bag deployability at 0 ° C cannot be improved. The content of the component e is 10 to 15 with respect to 100 parts by weight of the component a.
It can be suitably selected within the range of 0 parts by weight. Component e is 1
If the amount exceeds 50 parts by weight, the resulting elastomeric composition is inferior in rubber elasticity at high temperature and the airbag deployability at 90 ° C. is not preferable, and the heat-resisting shape retention property at high temperature is remarkably deteriorated. It cannot be used. Further, when the content of the component e is less than 10 parts 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.

In addition to the components (a) to (e) described above, the composition of the present invention may further contain, if necessary, an inorganic resin and an inexpensive resin such as polystyrene resin. . 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),
There are titanium oxide and the like, and as the carbon plaque, channel black, furnace black and the like 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 1,000.
The molecular weight distribution Mw can be selected from the range of 0-200000
/ Mn is preferably 5 or less. Further, if necessary, a nucleating agent, an external lubricant, an internal lubricant, a hindered amine light stabilizer, a hindered phenolic antioxidant, a colorant, silicone oil and the like may be added. As a method for producing the composition of the present invention, all general methods used for producing ordinary resin compositions and rubber compositions can be adopted. Basically, it is a mechanical melt kneading method, and these include a single-screw extruder, a twin-screw extruder, a Banbury mixer, various kneaders,
Brabender, roll, etc. are used. 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 can be suitably selected from 180 ° 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. Also, unnecessary burrs of injection molded products,
Since the composition of the present invention is thermoplastic, the runner portion and the spool portion can be recycled and molded, and have an advantage that they can be used again as a material for an airbag cover.

[0020]

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> polystyrene-hydrogenated polybutadiene-polystyrene structure, bound styrene content 30%
Asahi Kasei Tuftec H1041 [Hardness: 86] <Component b> Idemitsu Kosan Diana Process Oil PW-3
80 [paraffin type 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%] <Component c (1)> Amorphous olefin resin manufactured by Mitsui Petrochemical, Apel 130A [heat distortion temperature: 130 ° C] <Component c (2)> Amorphous olefin resin made by Japan Synthetic Rubber , ARTON I [heat distortion temperature: 165 ° C.] <Component c (3)> Amorphous olefin resin manufactured by Nippon Zeon, ZEONEX 280 [heat distortion temperature: 150]
℃] <Component c (4)> Polypropylene resin manufactured by Sumitomo Chemical, W5
01 [MFR (230 ° C.) = 8.0 g / 10 min Heat distortion temperature: 115 ° C.] <Component c (5)> Sumitomo Chemical polypropylene resin, AV
664B [MFR (230 ° C.) = 5 g / 10 minutes heat deformation temperature temperature: 122 ° C.] <Component d (1)> Ethylene-propylene copolymer rubber EP07P manufactured by Japan Synthetic Rubber [Propylene content: 25% by weight]
MFR (230 ° C) = 0.7 g / 10 minutes Tg: -38
° C] <Component d (2)> ethylene synthetic propylene-ethylidene norbornene copolymer rubber EP57P [propylene content: 28 wt% MFR (230 ° C) = 0.4
g / 10 minutes Iodine value: 15.0 Tg: -40 ° C "<Component e (1)> Santoprene 201- manufactured by Monsanto Co.
80 [vulcanizing agent: alkylphenol-formaldehyde resin embrittlement temperature: -60 ° C>] <Component e (2)> Sumitomo Chemical Sumitomo TPE821 [vulcanizing agent: organic peroxide embrittlement temperature: -60 ° C>]

<< Examples 1 to 18 and Comparative Examples 1 to 10 >> After thoroughly dry-blending the components shown in the table,
Using a twin-screw kneader, the mixture was melt-kneaded and extruded into pellets under conditions such that the resin temperature was 260 to 275 ° C. The following evaluation was performed using this pellet. (1) Hardness (JIS K6301): A press sheet was prepared and measured. (2) Appearance: An injection molding machine is used to prepare a molded product of an airbag cover having a thickness of 0.5 mm at the tear portion of the airbag cover and a thickness of 2 to 5 mm other than the tear portion of the airbag cover,
The appearance of flow marks, gloss, etc. was visually observed, and a good one was evaluated as ◯, a slightly defective one was evaluated as Δ, and a defective one was evaluated as x. (3) Heat-resistant shape retention: This airbag cover molded product is heated to a temperature of 9
A heat and shape retention test was conducted in an environment of 0 ° C. After 24 hours, the shape retention was good and no sagging was observed, and the sagging was taken as x. (4) Deployment test: This airbag cover molded product was subjected to an airbag deployment test at ambient temperatures of 85 ° C, 23 ° C and -40 ° C. The one that developed better than the cleaved part of the airbag cover was evaluated as ◯, and the one that cracked other than the cleaved part of the airbag cover, the cover was scattered, and the one where the airbag did not expand well were evaluated as x. The results are shown in Tables 1, 2 and 3 as Examples, and as Tables 4 and 5 as Comparative Examples. From these results, it is understood that the airbag cover formed by molding the composition obtained in the present invention has a hardness of 40 to 90 and is excellent in the airbag deployability at -40 ° C to 85 ° C.

[0022]

[0023]

[0024]

[0025]

[0026]

[0027]

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. Further, it has excellent long-term reliability because it has good light aging resistance and heat aging resistance. Moreover, compared with conventional urethane and nylon net for reinforcement, it has good moldability and good productivity.
The utility value is very high, such as easy color matching and low cost.

Claims (2)

[Claims] 1. A hydrogenated block copolymer elastomer composition comprising the following components a to d. (A) Hydrogenation of a block copolymer consisting of at least two terminal polymer blocks A mainly composed of vinyl aromatic compounds and an intermediate polymer block B mainly composed of at least one conjugated diene compound The resulting hydrogenated block co-polymer has a spring hardness (JIS K6301) of 99 or less 100 parts by weight (b) Paraffin oil 10 to 300 parts by weight (c) Amorphous olefin resin alone or amorphous olefin resin A blend of a resin and a crystalline olefin resin having a heat distortion temperature of 90 ° C. or more and a ratio of 25/75 or more (by weight) 5 to 250 parts by weight (d) Ethylene-α / olefin copolymer rubber and or 5 to 100 parts by weight of ethylene-α / olefin-non-conjugated diene copolymer rubber having a glass transition point of -30 ° C or lower 2. A hydrogenated block copolymer elastomer composition comprising the following components a to c and e. (A) Hydrogenation of a block copolymer consisting of at least two terminal polymer blocks A mainly composed of vinyl aromatic compounds and an intermediate polymer block B mainly composed of at least one conjugated diene compound Obtained hydrogenated block co-polymer having a spring hardness (JIS K6301) of 99 or less 100 parts by weight (b) Paraffin oil 10 to 300 parts by weight (c) Amorphous olefin resin alone or amorphous olefin resin A blend of a resin and a crystalline olefin resin having a heat distortion temperature of 90 ° C. or more and a ratio of 25/75 or more (weight) 5 to 250 parts by weight (e) dynamically vulcanized ethylene-α Thermoplastic elastomer composed of a blend of an olefin-non-conjugated diene copolymer rubber and a polyolefin resin and having an embrittlement temperature of -50 ° C or less 10 to 150 weight Quantity part