CA2031893A1 - Air bag-containing cover - Google Patents
Air bag-containing coverInfo
- Publication number
- CA2031893A1 CA2031893A1 CA002031893A CA2031893A CA2031893A1 CA 2031893 A1 CA2031893 A1 CA 2031893A1 CA 002031893 A CA002031893 A CA 002031893A CA 2031893 A CA2031893 A CA 2031893A CA 2031893 A1 CA2031893 A1 CA 2031893A1
- Authority
- CA
- Canada
- Prior art keywords
- cover
- ingredient
- air bag
- weight
- core layer
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Abandoned
Links
Classifications
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/08—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of synthetic resin
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R22/00—Safety belts or body harnesses in vehicles
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/06—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material
- B32B27/065—Layered products comprising a layer of synthetic resin as the main or only constituent of a layer, which is next to another layer of the same or of a different material of foam
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/18—Layered products comprising a layer of synthetic resin characterised by the use of special additives
- B32B27/22—Layered products comprising a layer of synthetic resin characterised by the use of special additives using plasticisers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/30—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers
- B32B27/302—Layered products comprising a layer of synthetic resin comprising vinyl (co)polymers; comprising acrylic (co)polymers comprising aromatic vinyl (co)polymers, e.g. styrenic (co)polymers
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/32—Layered products comprising a layer of synthetic resin comprising polyolefins
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B27/00—Layered products comprising a layer of synthetic resin
- B32B27/40—Layered products comprising a layer of synthetic resin comprising polyurethanes
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B5/00—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts
- B32B5/18—Layered products characterised by the non- homogeneity or physical structure, i.e. comprising a fibrous, filamentary, particulate or foam layer; Layered products characterised by having a layer differing constitutionally or physically in different parts characterised by features of a layer of foamed material
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B7/00—Layered products characterised by the relation between layers; Layered products characterised by the relative orientation of features between layers, or by the relative values of a measurable parameter between layers, i.e. products comprising layers having different physical, chemical or physicochemical properties; Layered products characterised by the interconnection of layers
- B32B7/02—Physical, chemical or physicochemical properties
- B32B7/022—Mechanical properties
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B60—VEHICLES IN GENERAL
- B60R—VEHICLES, VEHICLE FITTINGS, OR VEHICLE PARTS, NOT OTHERWISE PROVIDED FOR
- B60R21/00—Arrangements or fittings on vehicles for protecting or preventing injuries to occupants or pedestrians in case of accidents or other traffic risks
- B60R21/02—Occupant safety arrangements or fittings, e.g. crash pads
- B60R21/16—Inflatable occupant restraints or confinements designed to inflate upon impact or impending impact, e.g. air bags
- B60R21/20—Arrangements for storing inflatable members in their non-use or deflated condition; Arrangement or mounting of air bag modules or components
- B60R21/215—Arrangements for storing inflatable members in their non-use or deflated condition; Arrangement or mounting of air bag modules or components characterised by the covers for the inflatable member
- B60R21/2165—Arrangements for storing inflatable members in their non-use or deflated condition; Arrangement or mounting of air bag modules or components characterised by the covers for the inflatable member characterised by a tear line for defining a deployment opening
- B60R21/21656—Steering wheel covers or similar cup-shaped covers
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- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2250/00—Layers arrangement
- B32B2250/24—All layers being polymeric
- B32B2250/246—All polymers belonging to those covered by groups B32B27/32 and B32B27/30
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2323/00—Polyalkenes
- B32B2323/04—Polyethylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2323/00—Polyalkenes
- B32B2323/10—Polypropylene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2325/00—Polymers of vinyl-aromatic compounds, e.g. polystyrene
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2605/00—Vehicles
- B32B2605/003—Interior finishings
-
- B—PERFORMING OPERATIONS; TRANSPORTING
- B32—LAYERED PRODUCTS
- B32B—LAYERED PRODUCTS, i.e. PRODUCTS BUILT-UP OF STRATA OF FLAT OR NON-FLAT, e.g. CELLULAR OR HONEYCOMB, FORM
- B32B2605/00—Vehicles
- B32B2605/08—Cars
Abstract
ABSTRACT OF THE DISCLOSURE An air bag-containing cover comprising: a surface skin layer made Or a thermoplastic polymer containing the following ingredients A, B, C and D: ingredient A : a hydrogenated derivative of a block copolymer comprising styrene an conjugated diene, ingredient B : an olefinic resin, ingredient C : polyisobutylene with a viscosity average molecular weight of not greater than 70,000, and ingredient D : a hydrocarbon series rubber softening agent with a kinetic viscosity at 40 C of not greater than 500 cSt and/or polybutene with a number average molecular weight of not greater than 2500, in which blending ratio is : ingredient A = 40 to 80 % by weight, ingredient B = 5 to 30 % by weight, ingredient C = 2 to 30 % by weight ingredient D = O to 20 % by weight, and having a JIS-A hardness according to JIS-K6301 of from 20 to 90, and a core layer comprising an olefinic resin having a modulus in flexure according to JIS-K7203 of from 1000 to 7000 kg/cm2, in which the core layer has a higher hardness than that of the surface skin layer, and the core layer has a portion for easily bursting the cover upon initiation of the air bag operation.
Description
2~1893 AIR BAG-CONTAINING COVER
FIELD OF THE INVENTION AND RELATED ART STATEMENT
The present invention concerns a cover for containing an air bag which is actuated to expand and develop upon collision of a vehicle by sensing impact shock, deformation or the like caused by the collision.
The air bag-~ontaining cover of this kind is generally inserted with a reinforcing material such as nèts (refer, for example, to Jap~nese Patent Laid-Open Sho 62-234764, Sho 50-127336, Japanese Utility Model Laid-Open Sho 52-80928, Sho 50-43454 and Sho 51-25342).
The cover inserted with the net-like insarts is usually manufactured by preparing an entire cover with material of relatively low strength such as foamed polyurethane and inserting the reinforcing nets for the entire cover.
Lines not inserted with the reinforcing nets are generally provided so that the air bag can be developed smoothly upon expansion to easily break the cover.
On the other hand, Japanese Utility Model Laid-Open Sho 52-76042 proposes an air bag-containing cover compris-ing two layers, that is, a surface skin layer made of rigid urethane foams for finely finishing the surface and a core layer made of low density (high foaming ratio) 2~318~
urethanè foams for softening the entire cover in which slits (lines for smoothly developing the air bag upon expansion) ar~ disposed being èxtended from the cora layer to a portion of the surface skin layar.
Among the conventional air bag-containing covers described above, the air bag-containing cover provided with the n~t-like inserts involves a problem that its manufactur~ requires a number of steps and is troublesome, manufacture at high accuracy is difficult even by ths use, for example, of urethane foaming molding (RIM), thc pro-duction yield is low and the cost is expensive since the net-like rHinforcements are inserted.
Further, the cover as disclosed in Japanese Utility Model Laid-Open Sho 52-76042 has a surfacè skin layer made of rigid urethane foams (ASTM-D2240, Shore hardness: 30 -40) and, accordingly, it can not provide a soft fecling but gives unpleasant feeling when a portion of a driver's body is in contact therewith, for instance, during running Or a vehicle. Furthermore, since the urethane material has low impact shock strength and no reinforcing inserts are provided, broken pieces are scattered upon expansion of the air bag.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is to overcome the foregoing problems o~ the air bag-containing cover in the prior art and provids an air bag-containing cover of such a per~ormance that a surface skin layer is flsxibl2 and gives a soft ~eeling, a core layer retains a shape capable o~ withstanding external pressure, the cover is easily broken upon expanding operation of the air bag but is not scattered in broken pieces within a temperature range rrom -40 C to +8O C, and also shows satisfactory breaking performance with scarce change of appearance at the above-specified temperature range even a~-ter being for a long time at a high temperature o~ 110 C and 1000 hours in view of actual mounting to a vehicle, which can be supplied by means of a simple molding process such as injection molding, at a high yield in a method of not resulting in ~ailed products, at high accuracy, at high productivity and with satis~actory economical advantage.
The air bag-containing cover according to the present invention comprises:
a surface skin layer made of thermoplastic polymer containing the ~ollowing ingredients A, B, C and D, ingradient A : a hydrogenated derivative o~ a block copolymer comprising styrene and con~ugated diene, ingredient B : an ole~ini.c resin, ingredient C : a polyisobutylene with a viscosity average molecular weight o~ not greater than 70,000 and 2 ~ 3 ingredient D : a hydrocarbon series rubber sortening agent with a kinetic viscosity at 40 C Or not greater than 500 cSt and/or a polybutene with a number average molecular weight not greater than 2500, in which the blending ration is:
ingredient A = 40 to 80 % by weight.
ingredient B = 5 to 30 % by weight ingr~diant C = 2 to 30 % by weight ingredient D = 0 - 20 % by weight, and having JIS-A hardness in accordance with JIS-K6301 of from 20 to 90, and a core layer made of an olefinic resin having a modulus in flexure in accordance with JIS-K7Z03 Or f'rom 1000 to 7000 kg/cm2, in which the core layer has a higher hardness than that Or the surface skin layer snd the core layer is provided with easily bursting or tearing portions upon initiation Or the air bag operation.
The present inventors have made earnest studies for attaining the foregoing ob~ect and, as a result, have accomplishad tha prasent invention basèd on thè finding that the above-mentioned object can be attained by using a specific surface skin layer and a specific core layer and providing the core layer with easily bursting portions, for example, embrittled shapes.
In the air bag-containing cover according to the ~31~93 present invention, since the relatively rigid cora layer is covered with the sort surface skin layer, it provides softness and gives no unpleasant feeling when a driver's body is in contact with the cover. Further, since the core layer is rigid, the covsr is neither deform~d nor broken ev~n when a certain external ~orce is exerted.
In the cover according to the present invention, when the air bag in the cover is expanded, for instance, upon collision of a vehicle, within a temperature range ~rom -40 C to +80 C, the cover is bursted along the co~er burstlng embrittled shapes previously disposed to the core layer. Upon bursting Or the cover, since the rigid core layer is covered with the so~t sur~ace skin layer in close contact therewith, broken pieces of a cover upon bursting are not scattered.
Furthermore, the cover according to the present invention shows satisfactory breaking performancè and shows scarce change in the appearance within the above-mentioned temp~rature range (-40 C - +80 C) sven after the elapse of 5O0 hours at 110 C which are taken into consideration as actual mounting conditions to a vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic front elevational view partially in cross section illustrating an air bag-containing cover 2~31893 as a preferred embodiment according to the present inven-tion in a state attached to an air bag and Fig. 2 ls a rear elevational view of the air bag-containing cover.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described more in details.
Fig, 1 i8 a schematic rront elevational view partially in cross section illustrating an air bag-containing cover as a preferred embodimant according to the present inven-tion in a state attached to an air bag and Fig. 2 is a rear elevational view o~ the air bag-containing covar.
In the drawings, are shown an air bag-containing cover 1, an air bag 2, an inflator 3, a ring retainer 4, a base retainer 5, a plate 6, a rivet 7, a surface skin layer lA, a core layer lB and continuous stitch-like slits lC.
As shown in the drawings, the air bag-containing cover according to the present invention uses, as the surfaca layer lA, a surface skin layar made o~ a thermo-plastic polymer (thermoplastic elastomer) containing the ~ollowing ingredients A - D in the rollowing blending ratio and having JIS-A hardness in accordance JIS-K630 Or from 20 to 90;
Ingredient A : a hydrogenated derivative Or a block ~31~93 copolymer comprising styrene and con~ugated = 48 to 80 % by weight, Ingredient B : an ole~inic resin = 5 to 30 % by weight, Ingredient C : a polyisobutylene with a viscosity average molecular weight not greater than 70,000 = 2 to 30 % by weight, Ingredient D : a hydrocarbon series rubber softening agsnt with a kinetic viscosity at 40 C Or not greater than 500 cSt and/or a polybutene with a numbèr average molecular weight not greater than 2500 = 0 to 20 % by weight.
While on the other hand, a core layer made of an olerinic resin having a modulus inflexure in accordance with JIS-K7203 of from 1000 to 7000 kg/cm2 is used as the core layer lB.
The core layer lB has a higher hardness than that of the surface skin layer lA, and the core layer lB is pro-vided with embrittled shapes lC, ~or example, notch-like reduced thickness shapes or stitch-like slit shapes as the easily bursting portions upon initiation o~ the air bag operation.
In the present invention, as the ingredient A of the thermoplastic elastomer used as the constituent material for the surface skin layer lA, there can be mentioned a 2~31~3 hydrogenated derivative Or a styrenic block copolymer typically represented, for example, by the general formula:
X -Y
X~Y-X ) X~Y-X ~Y
where X represents a styrene polymer block, Y represents a conjugatsd diene elatomeric polymer and n is an integer oP 1 to 5.
As the monomer of the conjugated diene ror the polymer block Y in each Or the rormulae, butadiene or isoprene is suitable and a mixture thereof may also be used. Further, the ratio of the ingredient A of the styrene polymer block X in the entire block copolymer is usually ranges f rom 5 to 40 % by weight and, prersrably, from 10 to 35 % by weight. If the ratio is less than 5 % by weight, the surrace skin layer is deteriorated in the mechanical strength, easily broken upon expansion of the air bag and deformed by the external pressure to leave the traces thereof. On the other hand, if it exceeds 40 % by weight, it is not practical since the soft feeling Or the surface skin layer is poor.
It is preferred that the number average molecular weight Or the polymer block X is within a range from 5000 ~o 125000 and the number average molecular weight of the polymer block Y is within a range from 15000 to 250000.
2~3~93 Various methods have been proposed for the prepara-tion of the hydrogenated derivative of the styrenic block copolymer repres~nted by the general formula described above, and there can be mentioned typical methods as describad, for example, in Japanese Patent Publications Sho 42-8704 and 43-6636.
In the present invention, the hydrogenated derivative in which at loast 50%, preferably, more than 80% of the ola~inic double bonds in the polymer block Y are hydroge-nated and ].ess than 25% of the double bonds in the polymer block Y are hydrogenated upon preparation are pre~erred as the ingredient A. As ror the block polymer, commercially available polymer1 for example, KRATON-G (Shell Chemical Co.), KL (Kurare Co.) and TAFTEC (Asahi Kasei Co.) can be used.
As the ingrediqnt B, a homopolymer or copolymer of ~-ole~in such as ethylene, propylene and butene-1 is pre~rred.
As the ingredient C, a high molecular weight poly-isobutylene scarcely having double bonds in the molecular chain and having a bonding structure:
~C(CH3)2-CH2 ~
is preforred. The polyisobutylene for the ingredient C has a viscosity average molecular weight Or not greater than 2 ~ 9 3 70,000 and, preferably, not greater than 50,000. If the viscosity averaga molscular weight exceeds ~0,000, it is not preferred since this brings about a disadvantage that the resultant surface skin layer is poor in the so~t feeling and moldability. As a polyisobutylene suitable for the ingredient C, commercially available polymer, for example, TETRAX (Nippon Petrochemical Co.3 and BISTANEX
(Exon Chemical Co.) can be used.
The ingr~dient D is a hydrocarbon series rubber softening agent with a kinetic viscosity at 40 C of not greater than 500 cSt, specifically paraffinic or naphthenic extender oil or process oil and/or a polybutene with a number average molecular weight of not greater than 2500, preferably, not greater than 2,000, suitably, mainly com-prising isobutylene and partially copolymerized with n-butene.
If the kinetic viscosity of the hydrocarbon series rubber softening agent for the ingredient D exceeds 500 cSt, this result in a disadvantage that the moldability of the surface skin layer material is deteriorated. On the other hand, if the molecular weight of the polybutene exceeds 2500, it also leads to a disadvantage of poor moldability.
The ingredient D rnay be a mixture of a hydrocarbon series rubber softening agent and a polybutene.
2~31~93 In the present invention, the blending ratio of the ingredients A - D is as shown below:
Ingredisnt A = 40 to 80 wt%, preferably, 60 to 75 wt%
Ingredient B = 5 to 30 wt%, preferably, 10 to 20 wt%
Ingredient C - 2 to 30 wt%, preferably, 5 to 20 wt%
Ingredient D = O to 20 wt%, preferably, O to 15 wt%.
If the styrenic block polymer of th~ ingredient A is less than 40 % by weight, the resultant surface skin layer lacks in the soft feeling. On the other hand, if it e~ceeds 80 % by weight, the resultant thermoplastic elas-tomer has poor moldability.
If the olefinic resin of the ingredient B is less than 5 % by weight, the molding stability of the resultant thermoplastic elastomer and the adhesion between the sur-face skin layer and the core layer are poor. On the othar hand, if it exceeds 30 % by weight, the soft feeling of the resultant surface skin layer is poor.
If the polyisobutylene as the ingredient C is less than 2 % by weight, the soft feeling and th0 moldability are poor. If it exceeds 30 % by weight, it is not pre-ferred since the surface becomes sticky and physical strength is deteriorated.
If the hydrocarbon series rubber softening agent and/or polybuteno as the ingredient D exceeds 20 % by weight, it leads to undesirable appearance (deformation) 2~?~3 or the like after elapse Or 1000 hours at 110 C and causes ~ailure upon breaking, that is, breakage at the portions other than predetermined embrittled portions or scattering of broken pieces upon expansion of the air bag at -40 C.
In the pr0sent invention, a thermoplastic polymer constituting tha surface skin layer lA having JIS-A
hardness of 20 to 90 is selected. If the hardness is less than the above-specified range, the moldability (for example, injection moldability) and mechanical strength are poor, which results in easy destruction although the flexibility is satisfactory. On the other hand, if the hardness exceeds the above-mentioned rangè, it is not practical although since the soft feeling is poor, there is no problems in the moldability. The selècted hardness within a range from 20 to 90, although varying depending on the thickness of the surface skin layer, is preferably within a range from 30 to 70 and, more preferably, from 40 to 65.
The thermoplastic elastomer comprising the ingredients A - D for the surface skin layer lA in the present invention can be prepared by a mechanical melt-kneading. Specifically, usual melt-kneaders such as banbury mixer, various kinds of kneaders and extruders can be used. In the present invention, the constituent materials for the surface skin layer may comprise in addition to the ingredients A - D, various kinds of other resins, elastomers, various kinds 2~893 of fill~rs such as glass fibers, talc, calcium carbonate, silica and mica, pigments and stabilizers filled by a customary method, so long as the hardness is kept within the above-mentioned range.
The thickness of the surface skin layer lA usually varies dep~nding on the portions of the cover 1 and it is not quite uniform over the entire area. In the present inv0ntion, it is prefarred that those portions of more than 70 %, preferably, more than 80 % of the surface area Or the surface skin layer lA have a thickness of gr~ater than 0.5 mm. Although there is no particular restriction for the upper limit of the thickness, it is appropriate to keep the thickness to less than about 10 mm, for example in view of the design, economical property, soft feeling, oparation performanc~ and moldability of the air bag.
Further, with an aim of improving the soft feeling and r~duction Or t~ w~lg~t o~ the surrace skln layer lA, foaming at a ratio of less than about 3.0 times may be applied.
In the present invention, for the olefinic resin used as the constituent material for the core layer lB and having a modulus in rlexure according to JIS-K7203 of 1000 to 7000 kg/cm2 and having a higher hardness than of the thermoplastic polym0r for the sur~ace skin layer lA is, preferably, a homopolymer or a copolymer of ~ -olef$ns, 2~3~ ~393 ror example, ethylene and propylene. They may be used alone or as a blend of two or more of them. Furthermore, an elastomer, for example, an olefinic rubber comprising ethylene and ~ olefin may be added to the olefinic rssin with an aim of improving the softness, cold impact shock resistance or the like, so long as thc modulus in flexure and the hardnass are within the abovs specified range.
Further, various kinds of other resins, elastomers, various kind of fillers such as talc, calcium carbonate, lG silica or mica, pigments and stabilizers may be filled by a customary method so long the modulus and hardness are within the above-mentioned range.
In a case where the elastomer is contained in the material for the cors layer lB, the content is preferably not greater than 60 % by weight. If the olefinic rubber exceads 60% by weight in the blending composition of the olerinic resin and the elastomer, thare rises a problem in the moldability and the shape retainability.
In the present invention, ir the olefinic resin con-stituting the core layer lB has modulus flexure of not gr~ater than 1000 kg/cm2 or hardness lower than that of the thermoplastic elastomer for the surface skin laysr lA, it can not provide sufficient shape and is sasily deformed by external pressure and, accordingly, not suitable as an air bag-containing cover. On the other hand, if thc modulus 2Q3~3 in rlexure exceeds 7000 kg/cm , the entire softness of tha dual layer air bag cover is poor and the failure is liable to occur upon air bag operation at -40 C. Accordingly, the modulus in flexure is preferably greater than 1000 kg~cm2 and less than 7000 kg/cm2, particularly, 2000 to 5000 kg/cm2 in view of the soft feeling, operation characteristics and shape retainability of the entire cover.
There is no particular limit to the thickness of the core layer lB and it is generally about 0.5 to 5 mm and, preferably, 1 to 3 mm.
In the present invention, the core layer 1 constituted with such a thermoplastic resin is provided with embrittled shapes in order that the core layer lB is bursted upon initiation of the air bag operation. As the embrittled shapes, there can be used continuous stitch-like slit shapes lC, as well as various kinds of shapes such as notch-like shapes o~ reduced thickness. Further, there is no particular restriction to the position or range for forming the shapes, which may properly be determined depending on the shape and the strength of the core layer lB and the stresses caused upon air bag operation.
Then, description will now be made to the method of manu~acturing an air bag-containing cover according to the present invention.
As the molding m~thod for manufacturing the air bag-2 ~ 9 3 containing cover according to the prèsent invention, usual molding methods adopted for thermoplastic rssins can be mentioned and, in particular, injection molding method is pre~erred in viaw of the dasign or the like.
As the injection molding method, thera can be men-tioned, for example, a so-called insert injection method which comprises previously molding a core layer, placing the molding product to a die leaving a space for the surface skin layer and injection molding a surrace skin material comprising a thermoplastic polymer to the surface skin layer portion, or a so-called double injection method which comprises molding a core layer, aparting a cavity die, putting a nèw cavity die having a space for a sur~ace layer successively without taking the core molding product from the die and then in~ection molding the surface skin material.
In this case, it is necessary that the above-mentioned embrittled shapes are formed to the core layer lB so that air bag is easily bursted upon initiation of the operation.
As the embrittled shapes, there can be mentioned notch-li.ke shapes of reduced thickness continuous stitch-like slit shape, etc. as described above. The shapes may be applied by molding tha cover molding product with a die having such shape,s or by applying fabrication of provid-ing such shape and then laminating a surface skin layer 2~31~3 thereover a~ter molding the cover.
In the air bag cover according to the present inven-tion, the surrace skin layer lA may be applied with coating, if necessary, for providing gorgeousness in a v~hicle chamber and improving color matching with other interior parts and feeling. Coating of the surface skin layer lA
is also prererred in view of scratch resistance.
As has been described above specifically, since the surface layer in the air bag containing cover according to the present invention is soft, it provides a comfortable feeling due to its softness when a portion o~ a driver's body touches to the cover. Further, since the core layer is relatively hard, it is excellent in the shape retain-ability and highly durable. Then, upon operation Or the air bag, the cover is rapidly bursted due to the cover-bursting embrittled shapes. In addition, scattering of the core layer upon bursting of the covar can surely be prevented due to the soft surface skin layer and the cover exhibits preferable breaking per~ormance and it is excel-lent in endurance.
In addition, the air bag-containing cover according to the present invention can be manu~acturad, for example, by a rationalized molding process such as a double in~ec-tion method, simply, at high accuracy, with no occurrence of failed products, at high yield, effectively and effi-2Q3~893 ciently, which enables remarkable cost down o~ the resul-tant products.
The present invention will now be explainsd more specifically rererring to examples and comparative examples, but it should be noted that the present invention is not restricted only to the following examples unless it goes beyond the scope of the invsntion.
Examples 1 - 7, Comparative Examples 1 - 6 A core layer (1.0 - 3.0 mm thickness) applied with bursting stitch-like slits (29 slits, each of about 0.7 cm length) was molded from each of core materials shown in Table 1 by using an inline screw two-color injection molder with a die clamping pressure o~ 350 ton. Then, a surface skin layer was in~ection molded by using each Or a sur~ace skin materials shown in Table 1 to a predetermined thickness on the core layer, to obtain a module cover 1 for air bag shown in Fig. 1.
In Exampla 4, coating was applied on the surface skin layer.
The coating was applied by wiping the surface skin layer with isopropanol after injection molding of the cover, spray-coating a primer manufactured by Sakai Kagaku Co (MEX5440 and methyl ethyl ketone at 1:1 ratio) to 7 -10 um thickness, drying them at a room temperature for 10 2~3~89~
min, then coating a urathane top coat manufactured by Sakai Kagaku Co. (MEX-6047 : curing agent F-3L: thinner 58u = 100 : 10 : 50) to 20 - 25/um thickness, drying them at a room temperature for 10 min and then applying baking at 80 C for 30 - 45 min.
The resultant products wera evaluated by the method to be descrlbed later and the results are shown in Table-2.
The materials used shown in Table 1 and the manufac-turing methods are as follows.
(Core Material) P~-1 : Propylene-ethylene block copolymer resin (SPX 9800, manufactured by Mitsubushi Yuka Co.):
MFR (230 C, 2.16 kg) = 1 g/10 min, Modulus in flexure = 4500 kg/cm2 P~-2 : Propylene-athylene block copolymer resin (BC-8, manufactured by Mitsubushi Yuka Co.):
MFR (230 C, 2.16 kg) = 1.8 g/10 min, Modulus in flexure = 10800 kg/cm2 P~-3 : Ethylene-propylene rubber (EpO7p, manufactured by Nippon Synthetic Rubber Co.) ML (100 C) = 70 Propylene content = 27%
P~-4 : Low pressure polyethylene resin (JX-20, manu~actured by Mitsubushi Yuka Co.):
MFR (190 C, 2.16 kg) = 5.5 g/10 min, 2~318~3 Modulus in rlexure gooo kg/cm2 (Manufacturing method ror core ma-terial) 100 parts by weight of the core material with the blending composition as shown in Table-l was kneaded with addition of 0.2 parts of Illuganox 1010 manufactured by Ciba Geigy Co. as a stabillzer and 0.5 parts by weight o~
carbon black in a twine screw extruder at 200 C.
~Surface skin matsrial) Ingredient A
A-l: Hydrogenated dèrivative of styrene - butadiene block copolymer:
Styren8 content = 33 wt%
Number average molecular weight = 180000 A-2: Hydrogenated derivative of styrene - isoprene block copolymer:
Styrene content = 13 wt~
Number average molecular weight = 60000 Ingredient_B
B-l: The same material as P~-l used the ~or core material B-2: Propylene - ethylene block copolymer (BCl, manufactured by Mitsubishi Yuka Co.) :
MFR (230 C, 2.16 kg) = 30 g/10 min modulus in flexure = 10000 kg/cm2 2~2~893 Ingredient C
C-1 : Polyisobutylene (TETRAX 3T, manufactured by Nippon Petrochemical Co.):
Viscosity avarage molecular weight = 30000 C-2 : Polyisobutylene (TETRAX 5T, manufactured by Nippon Petrochemical Co.):
Viscosity average molecular weight = 50000 C-3 : Polyisobutynsne (VISTANEX MML-100, manu~actured by Exon Chemical) :
ln Viscosity average molecular weight = 90000 D-1: Para~inic rubber softening agent (OIL) (pw380, manufactured by Idemitsu Kosan Co.):
Kinetic viscosity at 40 C = 380 cSt D-2: Polybutene (Nisseki Polybutene HV-100, manu~actured by Nippon Petrochemical Co.) number avorage molecular weight = 970 (Manufacturing method for surface skin matsrial) 100 parts by weight of each of the ingredients in a blending composition shown in Table 1 was kneaded with addition of 0. 2 parts by weight of Illuganox 1010 and 0.5 parts by weight of carbon black used for the core ~aterial in a banbury type Xneader at 180 C for 20 min into a sheet-like form, which was then fabricated into square pellets by using a sheet cutter.
2 ~ 9~3 Comparative Example 7 For the comparison, an air bag-containing cover comprising two layers, that is, a surface skin layer made o~ high d~nsity urethane ~oams and a low density urethane core layer was manufactured and evaluated.
Molding was conducted by pr0viously molding and curing a core layer at low roaming density by a RIM urethane molding process, placing the same in a die for forming a surPace skin layer and, further, applying an insert molding process ror molding a surface skin layer in the same method. Fron gas was used as the foaming material for the molding Or the surface skin layer. The method rsqulred two curing steps and the productivity was poor.
The resultant air bag-containing cover was evaluated by the same method as in Example 1 and the results are shown in Table 2.
Comparative Example 8 For Purther comparison, an air bag-containing cover provided with reinforcing nets was manufactured and evaluated.
In this net-incorporated rim urethane molding, poly-ester fibei~s are braided into a net-like shape, which was cut by welding along the bursting shape of the cover and metal fixtures (hooks) were attached for molding two layers 2~31893 in the same way as in Comparative Example 7. They were placed in a rim die and applied with rim molding with urethane~ In this case, Fron gas was used as the foaming material and, a~ter mold releasing, cured at 100 C for 30 min. This method involves drawbacks that preparation of a safety skin layer by the insertion of nets is di~ficult and the molding cycle was not effectiv0.
The resultant air bag-containing cover was evaluated in the same method as in Example 1 and the results are shown in Table 2.
As apparent from Table 2, the air bag-containing covers according to the present invention shown in Examples 1 - 7 were 0xcellent for the soft ~eeling, shape retainability, developing test at -40 C, endurance test at 110 C for 500 hours and productivity.
(Evaluatlon Method) (1) Soft Feeling As shown in Fig. 1, a module cover incorporated with an air bag 2, an air bag-containing cover 1, retainers (attaching metal) 4, 5 and an inflator 3, or a cover 1 alone was left at -20 C - 80C such that the temperature of the sample reached atmospheric temperature and th~
covers were evaluated by means of feeling of hands of 10 persons. Evaluation was made by the number of persons who 2Q31~93 sensed soft feeling and indicated by "o" i~ ten out o~ ten persons felt soft and " ~" if 8 out of lO persons felt soft. "~" means that the number of persons who felt soft was less than 8.
(2) Shape Retainability A module cover attached with the air bag 2, the air bag-containing cover 1 and the retainer (metal fixturas) 4, 5 and the inflator 3 as shown in Fig. 1 or the cover 1 alone was left in the following heat cycles, i.e., lOO C x 4 hr -> -4O C x 4 hr ~
85 C x 98% (RH) 4 hr -~ -4O C, 4hr for lO cycles, and the state of deformation during or after the test was observed. (o) indicates suitability as the air bag-containing cover with scarce dePormation and (x) means insuitability as the air bag-containing cover with remarkable daformation.
FIELD OF THE INVENTION AND RELATED ART STATEMENT
The present invention concerns a cover for containing an air bag which is actuated to expand and develop upon collision of a vehicle by sensing impact shock, deformation or the like caused by the collision.
The air bag-~ontaining cover of this kind is generally inserted with a reinforcing material such as nèts (refer, for example, to Jap~nese Patent Laid-Open Sho 62-234764, Sho 50-127336, Japanese Utility Model Laid-Open Sho 52-80928, Sho 50-43454 and Sho 51-25342).
The cover inserted with the net-like insarts is usually manufactured by preparing an entire cover with material of relatively low strength such as foamed polyurethane and inserting the reinforcing nets for the entire cover.
Lines not inserted with the reinforcing nets are generally provided so that the air bag can be developed smoothly upon expansion to easily break the cover.
On the other hand, Japanese Utility Model Laid-Open Sho 52-76042 proposes an air bag-containing cover compris-ing two layers, that is, a surface skin layer made of rigid urethane foams for finely finishing the surface and a core layer made of low density (high foaming ratio) 2~318~
urethanè foams for softening the entire cover in which slits (lines for smoothly developing the air bag upon expansion) ar~ disposed being èxtended from the cora layer to a portion of the surface skin layar.
Among the conventional air bag-containing covers described above, the air bag-containing cover provided with the n~t-like inserts involves a problem that its manufactur~ requires a number of steps and is troublesome, manufacture at high accuracy is difficult even by ths use, for example, of urethane foaming molding (RIM), thc pro-duction yield is low and the cost is expensive since the net-like rHinforcements are inserted.
Further, the cover as disclosed in Japanese Utility Model Laid-Open Sho 52-76042 has a surfacè skin layer made of rigid urethane foams (ASTM-D2240, Shore hardness: 30 -40) and, accordingly, it can not provide a soft fecling but gives unpleasant feeling when a portion of a driver's body is in contact therewith, for instance, during running Or a vehicle. Furthermore, since the urethane material has low impact shock strength and no reinforcing inserts are provided, broken pieces are scattered upon expansion of the air bag.
OBJECT AND SUMMARY OF THE INVENTION
The object of the present invention is to overcome the foregoing problems o~ the air bag-containing cover in the prior art and provids an air bag-containing cover of such a per~ormance that a surface skin layer is flsxibl2 and gives a soft ~eeling, a core layer retains a shape capable o~ withstanding external pressure, the cover is easily broken upon expanding operation of the air bag but is not scattered in broken pieces within a temperature range rrom -40 C to +8O C, and also shows satisfactory breaking performance with scarce change of appearance at the above-specified temperature range even a~-ter being for a long time at a high temperature o~ 110 C and 1000 hours in view of actual mounting to a vehicle, which can be supplied by means of a simple molding process such as injection molding, at a high yield in a method of not resulting in ~ailed products, at high accuracy, at high productivity and with satis~actory economical advantage.
The air bag-containing cover according to the present invention comprises:
a surface skin layer made of thermoplastic polymer containing the ~ollowing ingredients A, B, C and D, ingradient A : a hydrogenated derivative o~ a block copolymer comprising styrene and con~ugated diene, ingredient B : an ole~ini.c resin, ingredient C : a polyisobutylene with a viscosity average molecular weight o~ not greater than 70,000 and 2 ~ 3 ingredient D : a hydrocarbon series rubber sortening agent with a kinetic viscosity at 40 C Or not greater than 500 cSt and/or a polybutene with a number average molecular weight not greater than 2500, in which the blending ration is:
ingredient A = 40 to 80 % by weight.
ingredient B = 5 to 30 % by weight ingr~diant C = 2 to 30 % by weight ingredient D = 0 - 20 % by weight, and having JIS-A hardness in accordance with JIS-K6301 of from 20 to 90, and a core layer made of an olefinic resin having a modulus in flexure in accordance with JIS-K7Z03 Or f'rom 1000 to 7000 kg/cm2, in which the core layer has a higher hardness than that Or the surface skin layer snd the core layer is provided with easily bursting or tearing portions upon initiation Or the air bag operation.
The present inventors have made earnest studies for attaining the foregoing ob~ect and, as a result, have accomplishad tha prasent invention basèd on thè finding that the above-mentioned object can be attained by using a specific surface skin layer and a specific core layer and providing the core layer with easily bursting portions, for example, embrittled shapes.
In the air bag-containing cover according to the ~31~93 present invention, since the relatively rigid cora layer is covered with the sort surface skin layer, it provides softness and gives no unpleasant feeling when a driver's body is in contact with the cover. Further, since the core layer is rigid, the covsr is neither deform~d nor broken ev~n when a certain external ~orce is exerted.
In the cover according to the present invention, when the air bag in the cover is expanded, for instance, upon collision of a vehicle, within a temperature range ~rom -40 C to +80 C, the cover is bursted along the co~er burstlng embrittled shapes previously disposed to the core layer. Upon bursting Or the cover, since the rigid core layer is covered with the so~t sur~ace skin layer in close contact therewith, broken pieces of a cover upon bursting are not scattered.
Furthermore, the cover according to the present invention shows satisfactory breaking performancè and shows scarce change in the appearance within the above-mentioned temp~rature range (-40 C - +80 C) sven after the elapse of 5O0 hours at 110 C which are taken into consideration as actual mounting conditions to a vehicle.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic front elevational view partially in cross section illustrating an air bag-containing cover 2~31893 as a preferred embodiment according to the present inven-tion in a state attached to an air bag and Fig. 2 ls a rear elevational view of the air bag-containing cover.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
The present invention will now be described more in details.
Fig, 1 i8 a schematic rront elevational view partially in cross section illustrating an air bag-containing cover as a preferred embodimant according to the present inven-tion in a state attached to an air bag and Fig. 2 is a rear elevational view o~ the air bag-containing covar.
In the drawings, are shown an air bag-containing cover 1, an air bag 2, an inflator 3, a ring retainer 4, a base retainer 5, a plate 6, a rivet 7, a surface skin layer lA, a core layer lB and continuous stitch-like slits lC.
As shown in the drawings, the air bag-containing cover according to the present invention uses, as the surfaca layer lA, a surface skin layar made o~ a thermo-plastic polymer (thermoplastic elastomer) containing the ~ollowing ingredients A - D in the rollowing blending ratio and having JIS-A hardness in accordance JIS-K630 Or from 20 to 90;
Ingredient A : a hydrogenated derivative Or a block ~31~93 copolymer comprising styrene and con~ugated = 48 to 80 % by weight, Ingredient B : an ole~inic resin = 5 to 30 % by weight, Ingredient C : a polyisobutylene with a viscosity average molecular weight not greater than 70,000 = 2 to 30 % by weight, Ingredient D : a hydrocarbon series rubber softening agsnt with a kinetic viscosity at 40 C Or not greater than 500 cSt and/or a polybutene with a numbèr average molecular weight not greater than 2500 = 0 to 20 % by weight.
While on the other hand, a core layer made of an olerinic resin having a modulus inflexure in accordance with JIS-K7203 of from 1000 to 7000 kg/cm2 is used as the core layer lB.
The core layer lB has a higher hardness than that of the surface skin layer lA, and the core layer lB is pro-vided with embrittled shapes lC, ~or example, notch-like reduced thickness shapes or stitch-like slit shapes as the easily bursting portions upon initiation o~ the air bag operation.
In the present invention, as the ingredient A of the thermoplastic elastomer used as the constituent material for the surface skin layer lA, there can be mentioned a 2~31~3 hydrogenated derivative Or a styrenic block copolymer typically represented, for example, by the general formula:
X -Y
X~Y-X ) X~Y-X ~Y
where X represents a styrene polymer block, Y represents a conjugatsd diene elatomeric polymer and n is an integer oP 1 to 5.
As the monomer of the conjugated diene ror the polymer block Y in each Or the rormulae, butadiene or isoprene is suitable and a mixture thereof may also be used. Further, the ratio of the ingredient A of the styrene polymer block X in the entire block copolymer is usually ranges f rom 5 to 40 % by weight and, prersrably, from 10 to 35 % by weight. If the ratio is less than 5 % by weight, the surrace skin layer is deteriorated in the mechanical strength, easily broken upon expansion of the air bag and deformed by the external pressure to leave the traces thereof. On the other hand, if it exceeds 40 % by weight, it is not practical since the soft feeling Or the surface skin layer is poor.
It is preferred that the number average molecular weight Or the polymer block X is within a range from 5000 ~o 125000 and the number average molecular weight of the polymer block Y is within a range from 15000 to 250000.
2~3~93 Various methods have been proposed for the prepara-tion of the hydrogenated derivative of the styrenic block copolymer repres~nted by the general formula described above, and there can be mentioned typical methods as describad, for example, in Japanese Patent Publications Sho 42-8704 and 43-6636.
In the present invention, the hydrogenated derivative in which at loast 50%, preferably, more than 80% of the ola~inic double bonds in the polymer block Y are hydroge-nated and ].ess than 25% of the double bonds in the polymer block Y are hydrogenated upon preparation are pre~erred as the ingredient A. As ror the block polymer, commercially available polymer1 for example, KRATON-G (Shell Chemical Co.), KL (Kurare Co.) and TAFTEC (Asahi Kasei Co.) can be used.
As the ingrediqnt B, a homopolymer or copolymer of ~-ole~in such as ethylene, propylene and butene-1 is pre~rred.
As the ingredient C, a high molecular weight poly-isobutylene scarcely having double bonds in the molecular chain and having a bonding structure:
~C(CH3)2-CH2 ~
is preforred. The polyisobutylene for the ingredient C has a viscosity average molecular weight Or not greater than 2 ~ 9 3 70,000 and, preferably, not greater than 50,000. If the viscosity averaga molscular weight exceeds ~0,000, it is not preferred since this brings about a disadvantage that the resultant surface skin layer is poor in the so~t feeling and moldability. As a polyisobutylene suitable for the ingredient C, commercially available polymer, for example, TETRAX (Nippon Petrochemical Co.3 and BISTANEX
(Exon Chemical Co.) can be used.
The ingr~dient D is a hydrocarbon series rubber softening agent with a kinetic viscosity at 40 C of not greater than 500 cSt, specifically paraffinic or naphthenic extender oil or process oil and/or a polybutene with a number average molecular weight of not greater than 2500, preferably, not greater than 2,000, suitably, mainly com-prising isobutylene and partially copolymerized with n-butene.
If the kinetic viscosity of the hydrocarbon series rubber softening agent for the ingredient D exceeds 500 cSt, this result in a disadvantage that the moldability of the surface skin layer material is deteriorated. On the other hand, if the molecular weight of the polybutene exceeds 2500, it also leads to a disadvantage of poor moldability.
The ingredient D rnay be a mixture of a hydrocarbon series rubber softening agent and a polybutene.
2~31~93 In the present invention, the blending ratio of the ingredients A - D is as shown below:
Ingredisnt A = 40 to 80 wt%, preferably, 60 to 75 wt%
Ingredient B = 5 to 30 wt%, preferably, 10 to 20 wt%
Ingredient C - 2 to 30 wt%, preferably, 5 to 20 wt%
Ingredient D = O to 20 wt%, preferably, O to 15 wt%.
If the styrenic block polymer of th~ ingredient A is less than 40 % by weight, the resultant surface skin layer lacks in the soft feeling. On the other hand, if it e~ceeds 80 % by weight, the resultant thermoplastic elas-tomer has poor moldability.
If the olefinic resin of the ingredient B is less than 5 % by weight, the molding stability of the resultant thermoplastic elastomer and the adhesion between the sur-face skin layer and the core layer are poor. On the othar hand, if it exceeds 30 % by weight, the soft feeling of the resultant surface skin layer is poor.
If the polyisobutylene as the ingredient C is less than 2 % by weight, the soft feeling and th0 moldability are poor. If it exceeds 30 % by weight, it is not pre-ferred since the surface becomes sticky and physical strength is deteriorated.
If the hydrocarbon series rubber softening agent and/or polybuteno as the ingredient D exceeds 20 % by weight, it leads to undesirable appearance (deformation) 2~?~3 or the like after elapse Or 1000 hours at 110 C and causes ~ailure upon breaking, that is, breakage at the portions other than predetermined embrittled portions or scattering of broken pieces upon expansion of the air bag at -40 C.
In the pr0sent invention, a thermoplastic polymer constituting tha surface skin layer lA having JIS-A
hardness of 20 to 90 is selected. If the hardness is less than the above-specified range, the moldability (for example, injection moldability) and mechanical strength are poor, which results in easy destruction although the flexibility is satisfactory. On the other hand, if the hardness exceeds the above-mentioned rangè, it is not practical although since the soft feeling is poor, there is no problems in the moldability. The selècted hardness within a range from 20 to 90, although varying depending on the thickness of the surface skin layer, is preferably within a range from 30 to 70 and, more preferably, from 40 to 65.
The thermoplastic elastomer comprising the ingredients A - D for the surface skin layer lA in the present invention can be prepared by a mechanical melt-kneading. Specifically, usual melt-kneaders such as banbury mixer, various kinds of kneaders and extruders can be used. In the present invention, the constituent materials for the surface skin layer may comprise in addition to the ingredients A - D, various kinds of other resins, elastomers, various kinds 2~893 of fill~rs such as glass fibers, talc, calcium carbonate, silica and mica, pigments and stabilizers filled by a customary method, so long as the hardness is kept within the above-mentioned range.
The thickness of the surface skin layer lA usually varies dep~nding on the portions of the cover 1 and it is not quite uniform over the entire area. In the present inv0ntion, it is prefarred that those portions of more than 70 %, preferably, more than 80 % of the surface area Or the surface skin layer lA have a thickness of gr~ater than 0.5 mm. Although there is no particular restriction for the upper limit of the thickness, it is appropriate to keep the thickness to less than about 10 mm, for example in view of the design, economical property, soft feeling, oparation performanc~ and moldability of the air bag.
Further, with an aim of improving the soft feeling and r~duction Or t~ w~lg~t o~ the surrace skln layer lA, foaming at a ratio of less than about 3.0 times may be applied.
In the present invention, for the olefinic resin used as the constituent material for the core layer lB and having a modulus in rlexure according to JIS-K7203 of 1000 to 7000 kg/cm2 and having a higher hardness than of the thermoplastic polym0r for the sur~ace skin layer lA is, preferably, a homopolymer or a copolymer of ~ -olef$ns, 2~3~ ~393 ror example, ethylene and propylene. They may be used alone or as a blend of two or more of them. Furthermore, an elastomer, for example, an olefinic rubber comprising ethylene and ~ olefin may be added to the olefinic rssin with an aim of improving the softness, cold impact shock resistance or the like, so long as thc modulus in flexure and the hardnass are within the abovs specified range.
Further, various kinds of other resins, elastomers, various kind of fillers such as talc, calcium carbonate, lG silica or mica, pigments and stabilizers may be filled by a customary method so long the modulus and hardness are within the above-mentioned range.
In a case where the elastomer is contained in the material for the cors layer lB, the content is preferably not greater than 60 % by weight. If the olefinic rubber exceads 60% by weight in the blending composition of the olerinic resin and the elastomer, thare rises a problem in the moldability and the shape retainability.
In the present invention, ir the olefinic resin con-stituting the core layer lB has modulus flexure of not gr~ater than 1000 kg/cm2 or hardness lower than that of the thermoplastic elastomer for the surface skin laysr lA, it can not provide sufficient shape and is sasily deformed by external pressure and, accordingly, not suitable as an air bag-containing cover. On the other hand, if thc modulus 2Q3~3 in rlexure exceeds 7000 kg/cm , the entire softness of tha dual layer air bag cover is poor and the failure is liable to occur upon air bag operation at -40 C. Accordingly, the modulus in flexure is preferably greater than 1000 kg~cm2 and less than 7000 kg/cm2, particularly, 2000 to 5000 kg/cm2 in view of the soft feeling, operation characteristics and shape retainability of the entire cover.
There is no particular limit to the thickness of the core layer lB and it is generally about 0.5 to 5 mm and, preferably, 1 to 3 mm.
In the present invention, the core layer 1 constituted with such a thermoplastic resin is provided with embrittled shapes in order that the core layer lB is bursted upon initiation of the air bag operation. As the embrittled shapes, there can be used continuous stitch-like slit shapes lC, as well as various kinds of shapes such as notch-like shapes o~ reduced thickness. Further, there is no particular restriction to the position or range for forming the shapes, which may properly be determined depending on the shape and the strength of the core layer lB and the stresses caused upon air bag operation.
Then, description will now be made to the method of manu~acturing an air bag-containing cover according to the present invention.
As the molding m~thod for manufacturing the air bag-2 ~ 9 3 containing cover according to the prèsent invention, usual molding methods adopted for thermoplastic rssins can be mentioned and, in particular, injection molding method is pre~erred in viaw of the dasign or the like.
As the injection molding method, thera can be men-tioned, for example, a so-called insert injection method which comprises previously molding a core layer, placing the molding product to a die leaving a space for the surface skin layer and injection molding a surrace skin material comprising a thermoplastic polymer to the surface skin layer portion, or a so-called double injection method which comprises molding a core layer, aparting a cavity die, putting a nèw cavity die having a space for a sur~ace layer successively without taking the core molding product from the die and then in~ection molding the surface skin material.
In this case, it is necessary that the above-mentioned embrittled shapes are formed to the core layer lB so that air bag is easily bursted upon initiation of the operation.
As the embrittled shapes, there can be mentioned notch-li.ke shapes of reduced thickness continuous stitch-like slit shape, etc. as described above. The shapes may be applied by molding tha cover molding product with a die having such shape,s or by applying fabrication of provid-ing such shape and then laminating a surface skin layer 2~31~3 thereover a~ter molding the cover.
In the air bag cover according to the present inven-tion, the surrace skin layer lA may be applied with coating, if necessary, for providing gorgeousness in a v~hicle chamber and improving color matching with other interior parts and feeling. Coating of the surface skin layer lA
is also prererred in view of scratch resistance.
As has been described above specifically, since the surface layer in the air bag containing cover according to the present invention is soft, it provides a comfortable feeling due to its softness when a portion o~ a driver's body touches to the cover. Further, since the core layer is relatively hard, it is excellent in the shape retain-ability and highly durable. Then, upon operation Or the air bag, the cover is rapidly bursted due to the cover-bursting embrittled shapes. In addition, scattering of the core layer upon bursting of the covar can surely be prevented due to the soft surface skin layer and the cover exhibits preferable breaking per~ormance and it is excel-lent in endurance.
In addition, the air bag-containing cover according to the present invention can be manu~acturad, for example, by a rationalized molding process such as a double in~ec-tion method, simply, at high accuracy, with no occurrence of failed products, at high yield, effectively and effi-2Q3~893 ciently, which enables remarkable cost down o~ the resul-tant products.
The present invention will now be explainsd more specifically rererring to examples and comparative examples, but it should be noted that the present invention is not restricted only to the following examples unless it goes beyond the scope of the invsntion.
Examples 1 - 7, Comparative Examples 1 - 6 A core layer (1.0 - 3.0 mm thickness) applied with bursting stitch-like slits (29 slits, each of about 0.7 cm length) was molded from each of core materials shown in Table 1 by using an inline screw two-color injection molder with a die clamping pressure o~ 350 ton. Then, a surface skin layer was in~ection molded by using each Or a sur~ace skin materials shown in Table 1 to a predetermined thickness on the core layer, to obtain a module cover 1 for air bag shown in Fig. 1.
In Exampla 4, coating was applied on the surface skin layer.
The coating was applied by wiping the surface skin layer with isopropanol after injection molding of the cover, spray-coating a primer manufactured by Sakai Kagaku Co (MEX5440 and methyl ethyl ketone at 1:1 ratio) to 7 -10 um thickness, drying them at a room temperature for 10 2~3~89~
min, then coating a urathane top coat manufactured by Sakai Kagaku Co. (MEX-6047 : curing agent F-3L: thinner 58u = 100 : 10 : 50) to 20 - 25/um thickness, drying them at a room temperature for 10 min and then applying baking at 80 C for 30 - 45 min.
The resultant products wera evaluated by the method to be descrlbed later and the results are shown in Table-2.
The materials used shown in Table 1 and the manufac-turing methods are as follows.
(Core Material) P~-1 : Propylene-ethylene block copolymer resin (SPX 9800, manufactured by Mitsubushi Yuka Co.):
MFR (230 C, 2.16 kg) = 1 g/10 min, Modulus in flexure = 4500 kg/cm2 P~-2 : Propylene-athylene block copolymer resin (BC-8, manufactured by Mitsubushi Yuka Co.):
MFR (230 C, 2.16 kg) = 1.8 g/10 min, Modulus in flexure = 10800 kg/cm2 P~-3 : Ethylene-propylene rubber (EpO7p, manufactured by Nippon Synthetic Rubber Co.) ML (100 C) = 70 Propylene content = 27%
P~-4 : Low pressure polyethylene resin (JX-20, manu~actured by Mitsubushi Yuka Co.):
MFR (190 C, 2.16 kg) = 5.5 g/10 min, 2~318~3 Modulus in rlexure gooo kg/cm2 (Manufacturing method ror core ma-terial) 100 parts by weight of the core material with the blending composition as shown in Table-l was kneaded with addition of 0.2 parts of Illuganox 1010 manufactured by Ciba Geigy Co. as a stabillzer and 0.5 parts by weight o~
carbon black in a twine screw extruder at 200 C.
~Surface skin matsrial) Ingredient A
A-l: Hydrogenated dèrivative of styrene - butadiene block copolymer:
Styren8 content = 33 wt%
Number average molecular weight = 180000 A-2: Hydrogenated derivative of styrene - isoprene block copolymer:
Styrene content = 13 wt~
Number average molecular weight = 60000 Ingredient_B
B-l: The same material as P~-l used the ~or core material B-2: Propylene - ethylene block copolymer (BCl, manufactured by Mitsubishi Yuka Co.) :
MFR (230 C, 2.16 kg) = 30 g/10 min modulus in flexure = 10000 kg/cm2 2~2~893 Ingredient C
C-1 : Polyisobutylene (TETRAX 3T, manufactured by Nippon Petrochemical Co.):
Viscosity avarage molecular weight = 30000 C-2 : Polyisobutylene (TETRAX 5T, manufactured by Nippon Petrochemical Co.):
Viscosity average molecular weight = 50000 C-3 : Polyisobutynsne (VISTANEX MML-100, manu~actured by Exon Chemical) :
ln Viscosity average molecular weight = 90000 D-1: Para~inic rubber softening agent (OIL) (pw380, manufactured by Idemitsu Kosan Co.):
Kinetic viscosity at 40 C = 380 cSt D-2: Polybutene (Nisseki Polybutene HV-100, manu~actured by Nippon Petrochemical Co.) number avorage molecular weight = 970 (Manufacturing method for surface skin matsrial) 100 parts by weight of each of the ingredients in a blending composition shown in Table 1 was kneaded with addition of 0. 2 parts by weight of Illuganox 1010 and 0.5 parts by weight of carbon black used for the core ~aterial in a banbury type Xneader at 180 C for 20 min into a sheet-like form, which was then fabricated into square pellets by using a sheet cutter.
2 ~ 9~3 Comparative Example 7 For the comparison, an air bag-containing cover comprising two layers, that is, a surface skin layer made o~ high d~nsity urethane ~oams and a low density urethane core layer was manufactured and evaluated.
Molding was conducted by pr0viously molding and curing a core layer at low roaming density by a RIM urethane molding process, placing the same in a die for forming a surPace skin layer and, further, applying an insert molding process ror molding a surface skin layer in the same method. Fron gas was used as the foaming material for the molding Or the surface skin layer. The method rsqulred two curing steps and the productivity was poor.
The resultant air bag-containing cover was evaluated by the same method as in Example 1 and the results are shown in Table 2.
Comparative Example 8 For Purther comparison, an air bag-containing cover provided with reinforcing nets was manufactured and evaluated.
In this net-incorporated rim urethane molding, poly-ester fibei~s are braided into a net-like shape, which was cut by welding along the bursting shape of the cover and metal fixtures (hooks) were attached for molding two layers 2~31893 in the same way as in Comparative Example 7. They were placed in a rim die and applied with rim molding with urethane~ In this case, Fron gas was used as the foaming material and, a~ter mold releasing, cured at 100 C for 30 min. This method involves drawbacks that preparation of a safety skin layer by the insertion of nets is di~ficult and the molding cycle was not effectiv0.
The resultant air bag-containing cover was evaluated in the same method as in Example 1 and the results are shown in Table 2.
As apparent from Table 2, the air bag-containing covers according to the present invention shown in Examples 1 - 7 were 0xcellent for the soft ~eeling, shape retainability, developing test at -40 C, endurance test at 110 C for 500 hours and productivity.
(Evaluatlon Method) (1) Soft Feeling As shown in Fig. 1, a module cover incorporated with an air bag 2, an air bag-containing cover 1, retainers (attaching metal) 4, 5 and an inflator 3, or a cover 1 alone was left at -20 C - 80C such that the temperature of the sample reached atmospheric temperature and th~
covers were evaluated by means of feeling of hands of 10 persons. Evaluation was made by the number of persons who 2Q31~93 sensed soft feeling and indicated by "o" i~ ten out o~ ten persons felt soft and " ~" if 8 out of lO persons felt soft. "~" means that the number of persons who felt soft was less than 8.
(2) Shape Retainability A module cover attached with the air bag 2, the air bag-containing cover 1 and the retainer (metal fixturas) 4, 5 and the inflator 3 as shown in Fig. 1 or the cover 1 alone was left in the following heat cycles, i.e., lOO C x 4 hr -> -4O C x 4 hr ~
85 C x 98% (RH) 4 hr -~ -4O C, 4hr for lO cycles, and the state of deformation during or after the test was observed. (o) indicates suitability as the air bag-containing cover with scarce dePormation and (x) means insuitability as the air bag-containing cover with remarkable daformation.
(3) Developing Test at -4O C
The assembled module in (1) and (2) above were attached to a steering wheel, left at -40 C for such a time as raaching the -temperature of the atmosphere and the developing test was applied within one min. (x) means insuitability as the air bag, not operating normally as the air bag, such as the module covar was cracked and scattered or the cover was cracked into sharp shapes to tear the bag and (o) means suitability showing that the 2~31~93 air bag operated normally.
The assembled module in (1) and (2) above were attached to a steering wheel, left at -40 C for such a time as raaching the -temperature of the atmosphere and the developing test was applied within one min. (x) means insuitability as the air bag, not operating normally as the air bag, such as the module covar was cracked and scattered or the cover was cracked into sharp shapes to tear the bag and (o) means suitability showing that the 2~31~93 air bag operated normally.
(4) Endurance Test at 110 C ror 1000 hours After aging the module cover under the above-mentioned conditions by a g0ar type thermal aging tester, -40 C
developing test was applied in accordance with the test method in (3) above and, furthar, the appearance of the module cover was compared between before and the aftar the aging. "x" means remarkable change such as warping, de-formation and blaeding of the softening agent to the core material, while "o" means with no such changes.
developing test was applied in accordance with the test method in (3) above and, furthar, the appearance of the module cover was compared between before and the aftar the aging. "x" means remarkable change such as warping, de-formation and blaeding of the softening agent to the core material, while "o" means with no such changes.
(5) Productivity 20 products wers manuractured successively and checked for the moldability (for example, mold releasability, or short shot), size and weight and, in particular, appearance Or products for the surrace skin layer (stickiness, dela-mination in the gatq portion, appearance of weld, molding sink flow mark, appearance Or grain, unevenness in luster, warping, or the like). "o" means that the are th0 products passed, " ~" means that more than 90% Or the products passes and "x" means that less than 90% Or them passed the check.
2~318~3 _ _ ~ ~V
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Claims
WHAT IS CLAIMED IS :
(1) An air bag-containing cover comprising:
a surface skin layer made of a thermoplastic polymer containing the following ingredients A, B, C and D:
ingredient A : a hydrogenated derivative of a block copolymer comprising styrene and conjugated diene, ingredient B : an olefinic resin, ingredient C : a polyisobutylene with a viscosity average molecular weight of not greater than 70,000, and ingredient D : a hydrocarbon series rubber softening agent with a kinetic viscosity at 40 C of not greater than 500 cSt and/or polybutene with a number average molecular weight of not greater than 2500, in which blending ratio is :
ingredient A = 40 to 80 % by weight, ingredient B = 5 to 30 % by weight, ingredient C = 2 to 30 % by weight ingredient D = 0 to 20 % by weight, and having a JIS-A hardness according to JIS-K6301 of from 20 to 90, and a core layer made of an olefinic resin having a modulus in flexure according to JIS-K7203 of from 1000 to 7000 kg/cm2, in which said core layer has a higher hardness than that Or said surface skin layer, and said core layer has a portion for easily bursting the cover upon initiation Or the air bag operation.
(2) A cover as defined in claim 11 wherein the portion for easily bursting the cover is notch-like thin walled portions or stitch-like slits disposed linearly.
(3) A cover as defined in claim 1, wherein the ingredient A is a hydrogenated derivative of a styrenic block copolymer typically represented, for example, by the general formula:
X-Y, X?Y-X)n or wherein X represents a polymer block Or styrene, Y is an elastomeric polymer block of conjugated diene and n is an integer of 1 to 5.
(4) A cover as defined in claim 3, wherein the monomer Or the conjugated diene for the polymer block Y in each Or the formulae described above is butadiene or isoprene.
(5) A cover as defined in claim 3, wherein the ratio Or the styrene block polymer X in the entire block copolymer of the ingredient A is from 5 to 40 % by weight.
(6) A cover as defined in claim 3, wherein the number average molecular weight of the polymer block X is from 5000 to 125000 and the number average molecular weight Or the polymer block Y is from 15000 to 250000.
(7) A cover as defined in claim 1, wherein the ingredient B is a homopolymer or copolymer of ?-olefin, for example, ethylene, propylene and butene-l.
(8) A cover as defined in claim 1, wherein the ingredient C is a high molecular weight polyisobutylene scarcely having double bonds in the molecular chain and having a bonding structure:
?C(CH3)2 CH2?n (9) A cover as defined in claim 1, wherein the hydro-carbon series rubber softening agent for the ingredient D
is a paraffinic or naphthenic extender oil or process oil.
(10) A cover as defined in claim 1, wherein the poly-butene with the number average molecular weight of not greater than 2500 for the ingredient D comprises mainly isobutylene and partially n-butene copolymerized therewith.
(11) A cover as defined in claim 1, wherein the surface skin layer 1A has a thickness from 0.5 mm to 10 mm for more than 70 % of the surface area of the surface skill layer 1A.
(12) A cover as defined in claim 1, wherein the surface skin layer 1A is applied with foaming at a ratio of less than about 3.0 times with an aim of improving the sort feeling and reduction of the weight.
(13) A cover as defined in claim 1, wherein the olefinic resin for the core layer is a homopolymer or copolymer of ?-olefin for example, ethylene and propylene.
(14) A cover as defined in claim 1, wherein the core layer further contains an elastomer.
(15) A cover as defined in claim 14, wherein the elastomer is an olefinic rubber comprising ethylene and ?-olefin.
(16) A cover as defined in claim 14, wherein the ratio Or the elastomer to the total amount of the olefinic resin and the elastomer is less than 60 % by weight.
(17) A cover as defined in claim 1, wherein the thickness of the core layer is from 0.5 to 5 mm.
(18) A cover as defined in claim 1, wherein the surface of the surface skin layer is applied with coating.
(19) An air bag device comprising:
a base retainer to be attached with an air bag, a folded air bag attached to said base retainer, an inflator attached to said base retainer so as to inject a gas into the air bag so as to rapidly develop said air bag and a cover as defined in claim 1, covering the air bag and secured to the base retainer.
(1) An air bag-containing cover comprising:
a surface skin layer made of a thermoplastic polymer containing the following ingredients A, B, C and D:
ingredient A : a hydrogenated derivative of a block copolymer comprising styrene and conjugated diene, ingredient B : an olefinic resin, ingredient C : a polyisobutylene with a viscosity average molecular weight of not greater than 70,000, and ingredient D : a hydrocarbon series rubber softening agent with a kinetic viscosity at 40 C of not greater than 500 cSt and/or polybutene with a number average molecular weight of not greater than 2500, in which blending ratio is :
ingredient A = 40 to 80 % by weight, ingredient B = 5 to 30 % by weight, ingredient C = 2 to 30 % by weight ingredient D = 0 to 20 % by weight, and having a JIS-A hardness according to JIS-K6301 of from 20 to 90, and a core layer made of an olefinic resin having a modulus in flexure according to JIS-K7203 of from 1000 to 7000 kg/cm2, in which said core layer has a higher hardness than that Or said surface skin layer, and said core layer has a portion for easily bursting the cover upon initiation Or the air bag operation.
(2) A cover as defined in claim 11 wherein the portion for easily bursting the cover is notch-like thin walled portions or stitch-like slits disposed linearly.
(3) A cover as defined in claim 1, wherein the ingredient A is a hydrogenated derivative of a styrenic block copolymer typically represented, for example, by the general formula:
X-Y, X?Y-X)n or wherein X represents a polymer block Or styrene, Y is an elastomeric polymer block of conjugated diene and n is an integer of 1 to 5.
(4) A cover as defined in claim 3, wherein the monomer Or the conjugated diene for the polymer block Y in each Or the formulae described above is butadiene or isoprene.
(5) A cover as defined in claim 3, wherein the ratio Or the styrene block polymer X in the entire block copolymer of the ingredient A is from 5 to 40 % by weight.
(6) A cover as defined in claim 3, wherein the number average molecular weight of the polymer block X is from 5000 to 125000 and the number average molecular weight Or the polymer block Y is from 15000 to 250000.
(7) A cover as defined in claim 1, wherein the ingredient B is a homopolymer or copolymer of ?-olefin, for example, ethylene, propylene and butene-l.
(8) A cover as defined in claim 1, wherein the ingredient C is a high molecular weight polyisobutylene scarcely having double bonds in the molecular chain and having a bonding structure:
?C(CH3)2 CH2?n (9) A cover as defined in claim 1, wherein the hydro-carbon series rubber softening agent for the ingredient D
is a paraffinic or naphthenic extender oil or process oil.
(10) A cover as defined in claim 1, wherein the poly-butene with the number average molecular weight of not greater than 2500 for the ingredient D comprises mainly isobutylene and partially n-butene copolymerized therewith.
(11) A cover as defined in claim 1, wherein the surface skin layer 1A has a thickness from 0.5 mm to 10 mm for more than 70 % of the surface area of the surface skill layer 1A.
(12) A cover as defined in claim 1, wherein the surface skin layer 1A is applied with foaming at a ratio of less than about 3.0 times with an aim of improving the sort feeling and reduction of the weight.
(13) A cover as defined in claim 1, wherein the olefinic resin for the core layer is a homopolymer or copolymer of ?-olefin for example, ethylene and propylene.
(14) A cover as defined in claim 1, wherein the core layer further contains an elastomer.
(15) A cover as defined in claim 14, wherein the elastomer is an olefinic rubber comprising ethylene and ?-olefin.
(16) A cover as defined in claim 14, wherein the ratio Or the elastomer to the total amount of the olefinic resin and the elastomer is less than 60 % by weight.
(17) A cover as defined in claim 1, wherein the thickness of the core layer is from 0.5 to 5 mm.
(18) A cover as defined in claim 1, wherein the surface of the surface skin layer is applied with coating.
(19) An air bag device comprising:
a base retainer to be attached with an air bag, a folded air bag attached to said base retainer, an inflator attached to said base retainer so as to inject a gas into the air bag so as to rapidly develop said air bag and a cover as defined in claim 1, covering the air bag and secured to the base retainer.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| JP1327580A JP2961780B2 (en) | 1989-12-18 | 1989-12-18 | Airbag storage cover |
| JP1-327580 | 1989-12-18 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| CA2031893A1 true CA2031893A1 (en) | 1991-06-19 |
Family
ID=18200645
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| CA002031893A Abandoned CA2031893A1 (en) | 1989-12-18 | 1990-12-10 | Air bag-containing cover |
Country Status (9)
| Country | Link |
|---|---|
| JP (1) | JP2961780B2 (en) |
| KR (1) | KR970008432B1 (en) |
| AU (1) | AU643957B2 (en) |
| CA (1) | CA2031893A1 (en) |
| DE (1) | DE4040396C2 (en) |
| ES (1) | ES2023612A6 (en) |
| FR (1) | FR2655908A1 (en) |
| GB (1) | GB2241665B (en) |
| IT (1) | IT1244471B (en) |
Families Citing this family (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CA2056206C (en) * | 1990-11-29 | 1996-02-06 | Norio Onofusa | Cover for accomodating air bag in air bag system |
| JPH04314648A (en) * | 1991-04-11 | 1992-11-05 | Takata Kk | Air bag storing cover |
| GB9115187D0 (en) * | 1991-07-13 | 1991-08-28 | Uta Clifford Limited | Crash protection device |
| TW209877B (en) * | 1991-11-04 | 1993-07-21 | Shell Internat Res Schappej B V | |
| JP2579956Y2 (en) * | 1991-12-09 | 1998-09-03 | 株式会社イノアックコーポレーション | Automotive airbag doors |
| JPH05286399A (en) * | 1992-04-08 | 1993-11-02 | Toyoda Gosei Co Ltd | Pad for air bag device |
| US5330223A (en) * | 1992-10-29 | 1994-07-19 | Toyoda Gosei Co., Ltd. | Air bag cover having reinforcing ribs |
| JPH0644652U (en) * | 1992-11-27 | 1994-06-14 | 豊田合成株式会社 | Airbag device |
| EP0646500B1 (en) * | 1993-09-29 | 1997-06-18 | Mercedes-Benz Ag | Dash-board for a motor vehicle |
| JP3020807B2 (en) * | 1994-07-22 | 2000-03-15 | 三菱化学株式会社 | Airbag storage cover |
| TW339348B (en) | 1994-11-04 | 1998-09-01 | Shell Internattonale Res Mij B V | Block copolymer containing composition suitable for used in air bag covers and air bag covers derived therefrom |
| JP3476355B2 (en) * | 1998-01-21 | 2003-12-10 | 日本プラスト株式会社 | Airbag storage case |
| DE60018355T2 (en) | 1999-11-18 | 2005-12-29 | Mitsubishi Chemical Corp. | Airbag cover for vehicles |
| DE102015220034A1 (en) * | 2015-10-15 | 2017-04-20 | Benecke-Kaliko Ag | Foil laminate and interior trim part for motor vehicles |
Family Cites Families (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4120516A (en) * | 1975-12-05 | 1978-10-17 | Nissan Motor Company, Limited | Cover member for a safety air-cushion device and a method of producing the same |
| DE3707370A1 (en) * | 1987-03-07 | 1988-09-15 | Kolbenschmidt Ag | SAFETY STEERING WHEEL |
| US4895389A (en) * | 1988-08-31 | 1990-01-23 | E. I. Dupont De Nemours And Company | Rupturable cover for a vehicle air bag compartment |
| US5110647A (en) * | 1988-12-26 | 1992-05-05 | Takata Corporation | Cover for a vehicle air bag |
| JPH0694266B2 (en) * | 1989-02-20 | 1994-11-24 | タカタ株式会社 | Airbag storage cover |
-
1989
- 1989-12-18 JP JP1327580A patent/JP2961780B2/en not_active Expired - Lifetime
-
1990
- 1990-12-06 AU AU67849/90A patent/AU643957B2/en not_active Expired - Fee Related
- 1990-12-10 CA CA002031893A patent/CA2031893A1/en not_active Abandoned
- 1990-12-10 GB GB9026807A patent/GB2241665B/en not_active Expired - Fee Related
- 1990-12-14 IT IT02239390A patent/IT1244471B/en active IP Right Grant
- 1990-12-14 KR KR1019900020638A patent/KR970008432B1/en not_active IP Right Cessation
- 1990-12-17 DE DE4040396A patent/DE4040396C2/en not_active Expired - Fee Related
- 1990-12-17 ES ES9003215A patent/ES2023612A6/en not_active Expired - Lifetime
- 1990-12-18 FR FR9015844A patent/FR2655908A1/en active Granted
Also Published As
| Publication number | Publication date |
|---|---|
| AU6784990A (en) | 1991-06-20 |
| DE4040396A1 (en) | 1991-06-20 |
| DE4040396C2 (en) | 1998-04-09 |
| JP2961780B2 (en) | 1999-10-12 |
| IT1244471B (en) | 1994-07-15 |
| GB2241665A (en) | 1991-09-11 |
| KR910011546A (en) | 1991-08-07 |
| ES2023612A6 (en) | 1992-01-16 |
| IT9022393A0 (en) | 1990-12-14 |
| FR2655908A1 (en) | 1991-06-21 |
| GB9026807D0 (en) | 1991-01-30 |
| FR2655908B1 (en) | 1995-05-12 |
| JPH03189252A (en) | 1991-08-19 |
| AU643957B2 (en) | 1993-12-02 |
| IT9022393A1 (en) | 1992-06-14 |
| GB2241665B (en) | 1993-09-29 |
| KR970008432B1 (en) | 1997-05-24 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| EEER | Examination request | ||
| FZDE | Discontinued | ||
| FZDE | Discontinued |
Effective date: 19950611 |