JPH06227356A - Air bag door automobile - Google Patents

Abstract

PURPOSE:To provide an automobile air bag door that is excellent in lightweightiness and safety as satisfying various physical properties being required to the air bag door, and simply manufactuable. CONSTITUTION:A door body part 16 and a mounting part 18 both are composed of a sandwich structural plastic between an inner layer 12 and an outer layer 14 surrounding this inner layer and covering it. This inner layer 12 consists of thermoplastic resin larger in Izod impact strength (23 deg.C notched, ASTM-D256 based) than 10kg.cm/cm. In addition, the outer layer 14 consists of thermoplastic resin, larger in bending elastic modulus (23 deg.C, ASTM-D790 based) than 10000kg/cm<2>, larger Izod impact strength (-40 deg.C notched, ASTM-D256 based) than 20kg.cm/cm, also larger in heat deformation temperature (4.6kg load, ASTM-D648 based) than 120 deg.C, respectively, thus this is automobile air bag door consisting of some resign different from the inner layer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an automobile airbag door.

[0002]

2. Description of the Related Art As shown in FIG. 6, a vehicle airbag door 50 includes an instrument panel 5 on the passenger side.
It is attached to an airbag deployment opening 54 formed on the second and other parts, and normally closes the deployment opening 54, and at the same time as an airbag (not shown) in an instrument panel or the like is inflated at the time of a vehicle collision. The opening 54 for deployment is opened so that the airbag can be deployed. It should be noted that a thin portion for breaking or a breakable locking piece is provided at a predetermined position of the airbag door 50, and when the airbag is inflated, the thin portion or the locking piece breaks to break the airbag door. It is supposed to open.

[0003] Conventionally, as the above-mentioned airbag door, as shown in FIG.
Alternatively, the airbag doors 60 and 70 shown in FIG. 8 are known. The former airbag door 60 includes a core layer 62 made of an aluminum plate, a foam layer 64 made of polyurethane foam, and a skin layer 66 made of vinyl chloride resin. The latter airbag door 70 is made of a single layer of resin, and the resin may be a simple substance of an elastomer or a composite resin of polyphenylene oxide and polyamide (P
PO / PA resin), composite resin of polyamide and modified polyolefin (PA / modified PO resin), composite resin of polycarbonate and acrylonitrile-butadiene-styrene copolymer (PC / ABS resin) and the like are used.
The term composite resin means a polymer alloy. In the figure, 68 and 72 are attachment parts to the opening for deployment, 69 is a locking piece for breaking, 74 is a thin part for breaking, and 76 is a hinge part.

[0004]

However, in the former airbag door 60, the core layer 62 of an aluminum plate is used.
Has a heavy problem. Further, when the airbag door 60 is opened, the mounting portion 68 made of aluminum is not deformed and restored, so that the airbag door remains in the maximum opened state, and the hand can be inserted into the deployment opening. There is a risk of getting burned. In addition, there is a problem that a lot of man-hours are required when forming the airbag door, and the work is time-consuming.

On the other hand, the latter airbag door 70 has the following problems. First, when an elastomer is used, since it has low rigidity, it is necessary to make it thicker or to provide ribs so as to have a predetermined rigidity. However, due to the thick wall or ribs, the airbag door becomes heavy,
Alternatively, there is a problem that deformation such as sink marks and warpage is likely to occur on the surface. When it is made of PPO / PA resin, it has poor heat aging resistance, and there is a problem that the airbag door is easily cracked when the airbag expands and expands after aging. Further, when it is composed of PA / modified PO resin, there is a problem that the hygroscopicity is high and the dimensional stability after water absorption is poor. When it is made of PC / ABS resin, it has poor chemical resistance and stress cracks.
There is a problem that is likely to occur.

The present invention solves the above-mentioned various problems and provides an automobile airbag door that satisfies various physical properties required for an airbag, is excellent in lightness and safety, and can be easily manufactured. Is.

[0007]

SUMMARY OF THE INVENTION The present invention provides an airbag door having a door main body and a mounting portion partially formed with a hinge, wherein the door main body and the mounting portion are an inner layer and an inner layer. It is made of a resin having a sandwich structure with an outer layer which surrounds and covers the inner layer, and the inner layer has an Izod impact strength (23 ° C. notched, according to ASTM-D256).
Is greater than 10 kg · cm / cm, and the outer layer has a flexural modulus (23 ° C., conforming to ASTM-D790) of more than 10,000 kg / cm ² , Izod impact strength (-40 ° C. notched, ASTM -D256 compliant) is 20
Greater than kgcm / cm, heat distortion temperature (4.6 kg load, AST
M-D648) is a thermoplastic resin having a temperature higher than 120 ° C. and is made of a resin different from the inner layer, and relates to an automobile airbag door.

[0008]

In the airbag door of the present invention, the door body and the mounting portion have a sandwich structure of an inner layer and an outer layer surrounding and covering the inner layer, and the inner layer has an Izod impact strength (23 ° C. notched, ASTM- D25
6 compliant) is made of a thermoplastic resin of greater than 10 kgcm / cm, and the outer layer has a flexural modulus (23 ° C, ASTM
-D790 compliant) is greater than 10,000 kg / cm ² , Izod impact strength (-40 ° C notched, ASTM-D256)
Conformity) is greater than 20 kgcm / cm, heat distortion temperature (4.6 kg
It is a thermoplastic resin whose load, ASTM-D648) is higher than 120 ° C and is made of a resin different from the inner layer, so that the physical properties and properties of the inner layer and the outer layer complement each other, and it is necessary for the airbag door as a whole. Holds various physical properties.

Moreover, the air bag door of the present invention is light in weight because it does not have an aluminum core layer as in the prior art and is made of resin. Further, since the mounting portion is also made of resin, the hinge portion formed on the mounting portion has resilience, and tends to close the door body portion after the airbag is deployed, that is, after the airbag door is opened.

In the present invention, the resin for the inner layer is Izod impact strength (notched at 23 ° C., ASTM-D256).
(Compliance) was set to be larger than 10 kg · cm / cm in order to prevent the airbag door from cracking when the airbag is deployed.
The flexural modulus of the resin for the inner layer is not particularly limited, but it is 15000 kg / cm ² (23 ° C,
It is more preferably larger than ASTM-D790).

The resin for the outer layer is made to have a flexural modulus (23
℃, according to ASTM-D790) was greater than 10000 kg / cm ^{2 in} order to give the airbag door self-shape retention, and Izod impact strength (notched at -40 ° C, according to ASTM-D256). The reason why the pressure is larger than 20 kg · cm / cm is to prevent the airbag door from breaking and scattering when the airbag is deployed at low temperature, and the thermal deformation temperature (4.6 kg load, ASTM-D648 compliant). Is set to more than 120 ° C. in order to prevent the airbag door from being deformed even when the airbag door becomes hot due to direct sunlight during parking in summer and the like.

The following may be mentioned as resins that can be used in the present invention. First, as the resin for the inner layer, a composite resin of polyphenylene oxide and polyamide (PPO / PA resin), a composite resin of polyamide and modified polyolefin (PA / modified PO resin), a polycarbonate and an acrylonitrile-butadiene-styrene copolymer are used. Composite resin (PC / ABS resin), polypropylene (PP) resin, acrylonitrile-styrene (A
An S) resin or the like having the above-mentioned physical properties required for the inner layer resin is used.

The polyphenylene oxide (P
Polyamide (PA) compounded with PO) is 6-
Nylon, 6,6-nylon, 11-nylon, 12-
Polymers such as nylon, copolymers of raw materials thereof, polyester polyamide obtained by condensation polymerization of polymer polyester having a carboxyl group at both ends obtained from glycol and diol compound, and diamine compound,
Alternatively, there are composite resins thereof.

Examples of the polyamide in the composite resin of polyamide and modified polyolefin (PA / modified PO resin) include 6-nylon and / or 6,6-nylon. Examples of the modified polyolefin include a polyolefin resin having a carboxyl group introduced. Further, the polyamide and the modified polyolefin may or may not be chemically bonded, and when they are bonded, a chemical reaction between the terminal amine in the polyamide and the carboxyl group introduced into the polyolefin results in It consists of the resulting amide bond.

The composite resin (PC / ABS resin) of polycarbonate (PC) and acrylonitrile-butadiene-styrene copolymer (ABS) is not particularly limited.

The polypropylene (PP) resin includes
Although not particularly limited, a filler such as talc may be added. The acrylonitrile-styrene (AS) resin is a resin containing acrylonitrile and styrene as essential components, and includes acrylonitrile-styrene block copolymer (AS), acrylonitrile-butadiene-styrene copolymer (ABS), and acrylonitrile-ethylene-styrene. Examples thereof include a copolymer (AES) and an acrylonitrile-acrylic rubber-styrene copolymer (AAS) resin.

On the other hand, as the resin for the outer layer, the above-mentioned PPO / P is used.
A resin, such as A resin, PA / modified PO resin, PC / ABS resin, etc., which satisfies the above-mentioned physical properties required for the resin for the outer layer and is different from the resin for the inner layer is used.

Additives are appropriately added to the resin for the inner layer or the outer layer. As additives, antioxidants,
Examples thereof include UV absorbers, fluidity improvers, reinforcing materials (fillers, fibers), and the like.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to the accompanying drawings. 1 is a sectional view showing an embodiment of the present invention, FIG.
Is a perspective view of the same embodiment, FIGS. 3 and 4 are cross-sectional views showing the airbag door in the same embodiment at the time of molding, and FIG. 5 is a cross-sectional view showing another embodiment.

The airbag door 10 shown in FIGS. 1 and 2 is attached to an airbag deployment opening formed on the passenger side of an instrument panel of an automobile, and surrounds the inner layer 12 and the inner layer 12. Outer layer 14 for coating
And a door body 16, a mounting portion 18, and a locking component mounting seat 2
It consists of zero.

The inner layer 12 has an Izod impact strength (2
Notched at 3 ° C, conforming to ASTM-D256) 10kgcm
/ Cm, outer layer 14 has a flexural modulus (23 ° C, AST
M-D790 compliant> 10,000 kg / cm ² , Izod impact strength (-40 ° C notch, ASTM-D25)
6) is greater than 20 kgcm / cm, heat distortion temperature (4.6
It is made of a thermoplastic resin having a load of kg, conforming to ASTM-D648) of more than 120 ° C.

The door body 16 is a plate-like member having a size capable of closing the opening for deploying the airbag. The attachment portion 18 is for attaching the airbag door 10 to the edge of the opening for expanding the airbag, and is formed to continuously project from the door body portion 16 to the edge of the back surface of the door body portion 16. A hinge 19 for enabling the opening of the airbag door 10 is provided at a part of the mounting portion 18. The hinge 19 part is formed thinner than the other parts of the attachment part 18.

The locking component mounting seat 20 is bent in a substantially L-shape and has a forked end 21, and is formed to project on the edge of the back surface of the airbag door body 16. A fork 21 at the tip of the mounting seat 20 has a locking piece 22 made of synthetic resin.
Is locked. The locking piece 22 is locked inside the opening for expanding the airbag, and normally closes the airbag door 10. When the airbag is inflated and expanded, the locking piece 22 is broken at the neck portion 23 so that the airbag door 10 can be opened. It is made of polyester elastomer or the like.

The airbag door 10 of this embodiment is shown in FIG.
Using the molding die 30 shown in FIG. 4 and the conventional sandwich molding method, it is obtained as follows. First,
As shown in FIG. 3, the resin A for outer layer in a heat-melted state is injected into the cavity 32 of the molding die in a somewhat smaller amount than the internal volume of the cavity 32 (so-called short shot state). The injection amount at this time is an amount capable of forming a resin layer of about 2 to 3 mm on the inner wall surface of the cavity 32.

Immediately after that, in place of the outer layer resin A, the inner layer resin B in a heated and melted state is injected to fill the cavity 32 with the outer layer resin A and the inner layer resin B. At this time, the inner layer resin B injected later advances in the outer layer resin A while pushing the previously injected outer layer resin A.
Finally, the inside of the cavity 32 is filled with the outer layer resin A and the inner layer resin B surrounded and covered with the outer layer resin A. Then, after waiting for the resin to cool and cure, the molded product is released from the mold to obtain the airbag door 10.

Table 1 shows the airbag door 10 having the above construction.
5 shows the physical properties of the inner layer and the outer layer, and the test results of the airbag door for Examples 1 to 5, which are formed by changing the combination and types of the resins forming the inner layer 12 and the outer layer 14. Moreover, Table 2 shows a comparative example.

The test method is as follows. Flexural modulus at room temperature (23 ° C) conforms to ASTM-D790, Izod impact strength is ASTM-D25 with inner layer notched at 23 ° C
6-compliant, outer layer is -40 ° C with notch ASTM-D25
6 (outer layer), heat distortion temperature is AST with 4.6kg load
It measured based on M-D648.

In the airbag deployment test at -40 ° C, the airbag door is attached to a canister (airbag case), left at an ambient temperature of -40 ° C for 1 hour, and released from the atmosphere within 1 minute. It was carried out by deploying the bag and observing the damaged state and the operating state of the airbag door. The evaluation was conducted when the airbag door was cracked and did not operate normally (x), when the airbag operated normally, but cracks and whitening were observed (△), and when the airbag operated without any damage (○) ). Also, the hinge restoration property is that if the airbag door is left open after opening the airbag and the canister opening is visible (×), the airbag door blocks the canister opening due to the hinge restoration and the canister opening is not visible. In case (○).

In the heat aging expansion test, the airbag door is left in an oven at an atmospheric temperature of 110 ° C. for 1200 hours, taken out and left at room temperature (23 ° C.) for 1 day, and then attached to a canister at -40 ° C. The airbag was deployed in the same manner as in the deployment test of 1., and the damaged state and the operating state of the airbag door were observed.
The evaluation was made when the airbag door was cracked and did not operate normally (x), and when the airbag door operated normally without any cracks or damage (◯).

In the deployment test after the chemical test, after applying gasoline on the surface of the airbag door, the airbag door is left at room temperature (23 ° C.).
After being left for 1 week, it was attached to a canister and subjected to a development test and evaluation in the same manner as the development test after heat aging.

The rate of water absorption dimensional change was 23 for the airbag door.
After leaving it in water at ℃ for 100 hours, take it out and measure its dimensions.
The rate of change from the original dimensions was calculated.

The heat deformability of the air bag door is 110 ° C.
After being left in the oven for 1200 hours and then taken out, the appearance of the airbag door was observed, and when the deformation was observed (x), the case where no deformation was observed (o) was evaluated. Regarding the weight, the weight of Comparative Example 6 was defined as 100%, and the percentage was shown.

(Example 1) PPO / P as the resin for the outer layer
PA / modified PO composite resin [Product name: Toray Nylon U] as the resin for the inner layer using A composite resin [Product name: "Noryl GTX" (manufactured by Japan GE Plastics Co., Ltd.)]
TN "(manufactured by Toray Industries, Inc.)] was used.

(Example 2) PA / modified PO composite resin [trade name; "Toray Nylon UTN" (manufactured by Toray Industries, Inc.)] was used as the resin for the outer layer, and PC / ABS was used as the resin for the inner layer.
A composite resin [trade name; "Multilon" (manufactured by Teijin Kasei Co., Ltd.)] was used.

Example 3 PA / modified PO composite resin [trade name; "Toray Nylon UTN" (manufactured by Toray Industries, Inc.)] was used as the resin for the outer layer, and talc-containing P was used as the resin for the inner layer.
P resin [trade name; "UBE Polypro" (manufactured by Ube Industries, Ltd.)] was used.

Example 4 PC / AB as the resin for the outer layer
S composite resin [trade name; "Multilon" (manufactured by Teijin Kasei Co., Ltd.)] and ABS resin as a resin for the inner layer [trade name: "Superlex M" (manufactured by Mitsubishi Kasei Co., Ltd.)]
Was used.

Example 5 PC / AB as the resin for the outer layer
Use S composite resin [trade name; "Multilon" (manufactured by Teijin Kasei Co., Ltd.)] and use PPO / PA composite resin [trade name; "Noryl GTX" (manufactured by GE Plastics Co., Ltd.)] for the inner layer resin. I was there.

Comparative Example 1 PPO / as a constituent resin raw material
A single layer airbag door was molded by ordinary injection molding using PA composite resin [trade name: "Noryl GTX" (manufactured by Japan GE Plastics Co., Ltd.)]. The outer shape is the same as that of the first to fifth embodiments.

(Comparative Example 2) A PA / modified PO composite resin [trade name; "Toray Nylon UTN" (manufactured by Toray Industries, Inc.)] was used as a constituent resin raw material and molded in the same manner as in Comparative Example 1. (Comparative Example 3) PC / ABS composite resin [trade name; "Multilon" (manufactured by Teijin Kasei Co., Ltd.)] was used as a constituent resin raw material and molded in the same manner as in Comparative Example 1.

(Comparative Example 4) A polyamide elastomer [trade name; "DAIAMID" (manufactured by Daicel Hüls Ltd.)] was used as a constituent resin raw material and molded in the same manner as in Comparative Example 1. (Comparative Example 5) An olefinic elastomer [trade name; "Milastomer" (manufactured by Mitsui Petrochemical Industries, Ltd.)] was used as a constituent resin raw material and molded in the same manner as in Comparative Example 1.

Comparative Example 6 A three-layer structure having a core layer made of an aluminum plate, a foam layer made of a polyurethane foam, and a skin layer made of vinyl chloride resin was molded into the same shape as that of the example.

[0042]

[Table 1]

[0043]

[Table 2]

As can be seen from Tables 1 and 2, the airbag door of the present invention is not easily damaged at low temperatures, has excellent heat aging resistance, chemical resistance, water absorption dimension stability, and heat deformation resistance, and has a hinge. And has a lighter weight than the conventional airbag door (Comparative Example 6) having the aluminum core layer.

The airbag door of the present invention is not limited to the one using the locking piece 22 as described above, but is attached to both edges of the door main body 42 like the airbag door 40 shown in FIG. It may have the portions 44 and 46, and the thin portion 48 for breaking is formed on one of the attachment portions 46. Reference numeral 45 is an inner layer, 47 is an outer layer, and 49 is a hinge.

[0046]

Since the airbag door of the present invention is constructed as described above, it not only satisfies the physical properties required for the airbag door and is highly safe, but it is also lightweight. Further, when forming an airbag door, there is an advantage that it can be formed extremely easily by a known sandwich forming method.

[Brief description of drawings]

FIG. 1 is a sectional view showing an embodiment of the present invention.

FIG. 2 is a perspective view of the same embodiment.

FIG. 3 is a cross-sectional view of the airbag door in the same embodiment at the time of molding, showing an outer layer injection time.

FIG. 4 is a cross-sectional view showing the injection of the inner layer in the example.

FIG. 5 is a sectional view showing another embodiment.

FIG. 6 is a perspective view of an instrument panel in the vicinity of a passenger seat airbag door.

FIG. 7 is a sectional view of a conventional airbag door.

FIG. 8 is a sectional view showing another example of a conventional airbag door.

[Explanation of symbols]

 10 Airbag Door 12 Inner Layer 14 Outer Layer 16 Door Main Body 18 Attachment Part 19 Hinge A Outer Layer Resin B Inner Layer Resin

Claims (1)

[Claims] 1. An automobile airbag door having a door main body and a mounting portion partially formed with a hinge, wherein the door main body and the mounting portion cover an inner layer and surround the inner layer. It is made of a resin having a sandwich structure with an outer layer, and the inner layer has an Izod impact strength (23 ° C notched, A
STM-D256 compliant) is composed of a thermoplastic resin having a size of more than 10 kg · cm / cm, and the outer layer has a flexural modulus (23 ° C., ASTM-D790).
Compliant) is greater than 10000 kg / cm ² , and Izod impact strength (-40 ° C notched, ASTM-D256 compliant) is 2
Greater than 0 kg / cm / cm, heat distortion temperature (4.6 kg load, AS
TM-D648) is a thermoplastic resin having a temperature of higher than 120 ° C. and is made of a resin different from the inner layer.