JPH01122753A - Air-bag storage casing - Google Patents

Abstract

PURPOSE:To enhance the ease of breakage of an upper surface part of a casing by laminating a foamed thermoplastic resin sheet on one surface of a core member formed of a fibrous sheet impregnated with thermohardenable resin, and by making the amount of impregnation with the thermohardenable resin in the upper surface part of the core member less than that of a side surface part thereof. CONSTITUTION:Crosslinked foamed sheet 3 made of polyethylene having a foam multiplying rate of 20 with a thickness of about 4mm is jointed and bonded on the outer surface of a core member 2 formed by impregnating a fibrous sheet such as felt or the like with unsaturated polyester resin which is thereafter hardened, by a hot-melt bonding agent so as to form a box 1 having it lower surface opened. An unfoamed flexible skin layer which is formed by blending low density polyethylene and high density polyethylene in TPO (polyolefin group thermoplastic elastomers) is laminated on the outer surface of the foamed sheet 3. Further, in this arrangement, a line-like or perforated thin wall part 13 is formed in the upper surface 11 of the box 1, and the amount of impregnation with thermohardenable resin in an area (a) of an upper surface section 21 of the core member 2 is less than that of an area (b) of a side surface section 22 thereof.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an airbag storage case for an airbag device that automatically inflates to protect occupants in the event of a car crash, for example.

[Prior art]

Conventionally, various types of storage cases for airbags have been proposed1, for example, Utility Model Publication No. 58-19887 KVi has a groove that projects inwardly and has a broken thin wall at the bottom that is thinner than the general wall thickness. A cushion cover is described which is formed integrally with a resin outer skin having a sectional area and a one-piece cover containing a core material. In this case, a skin with a Fi fractured thin-walled part is produced, and then the skin and core material are placed in a predetermined mold having an inner surface that matches the outer shape of the skin, and a foaming agent is added to foam this. Manufactured by

[Problem that the invention seeks to solve]

According to the above-mentioned conventional technology, the thin-walled areas of the core material Fi, which is enclosed in order to give rigidity and strength to the cushion cover, must be separated by a predetermined distance, and the core material must be separated from the part where the car body is attached. Since the material is uniform throughout from the thin walled portion K to the thin walled portion K, it was difficult to match the strength of the core material with the breaking force that occurs when the gas generator operates and the cushion cover breaks at the thin walled portion.

[Means for solving problems]

The present invention has been made to solve the above-mentioned conventional drawbacks.1. The purpose of this study is to provide a box made of a laminate in which a thermoplastic resin foam sheet is laminated on at least one side of a core material in which a fibrous sheet is impregnated and cured with a thermosetting resin. The airbag storage case is characterized in that the lower surface of the box is open, and the upper surface of the core material constituting the box has a smaller amount of thermosetting resin impregnated than the side surfaces.

The materials of the fibrous sheet used in the present invention include natural fibers such as cotton, hemp, pulp, animal hair, asbestos, and rock wool, cellulose, polyamide, polyvinyl alcohol, polyester, polyethylene, and polypropylene. There are also synthetic fibers, drawn products of these synthetic resins, glass fibers, etc. Fibrous sheet #-i It is used as woven fabrics, knitted fabrics, non-woven fabrics, 7-elts, chopped strands of glass fibers, etc.

In order to partially strengthen or weaken the breaking strength of the fibrous sheet, the type and type of fibers are appropriate as necessary.

Thermosetting resins include unsaturated polyester, epoxy,
Phenol or the like is used, and a curing accelerator is added if necessary.

Impregnating a fibrous sheet with TLC thermosetting resin means that from a state in which the fibrous sheet is filled with thermosetting resin until no air bubbles remain between the fibers, only individual fibers are filled with thermosetting resin. Coated with fiber #1rPdKF! This term refers to all conditions in which a large number of air bubbles are present, or a large number of air bubbles communicate between the front and back surfaces of a fibrous sheet, leading to air permeability and water permeability.

The thickness of the core material formed by impregnating and curing a thermosetting resin into a fibrous sheet is suitably about 1 to 8 ff, more preferably about 3 to 6 fl. The thickness may be partially thick or thin.

In addition, lamps, polyolefin resin foam sheets, polyvinyl chloride foam sheets, polyurethane foam sheets, etc. are used as the thermoplastic resin foam sheets used in the present invention.
Polyolefin resin foam sheets are lightweight and easy to manufacture.
It is preferable because it is inexpensive and has good workability.

The above-mentioned polyolefin resin foamed sheet) K The olefin thread resins used include low density polyethylene, medium density polyethylene, high density polyethylene, and linear low density polyethylene (linear low density polyethylene; LLDP).
E), polymers such as polypropylene, or polymers containing ethylene as a main component, such as ethylene-vinyl acetate copolymer, ethylene-propylene copolymer, ethylene-
A copolymer such as an α-olefin copolymer, or a mixture of two or more of these polymers or copolymers is used,
A cross-linked foam sheet is preferred.

The foaming ratio of the foamed sheet is preferably alO to 50 times,
More preferably it is 10 to 40 times.

Further, the appropriate thickness of the foam sheet is Fi1 to 10 m01. If it is thinner than Iff, it will easily tear when laminated onto a box-shaped core material and lack a soft feel.

If it exceeds the reverse vclOff, it will not fit well into the molded core material and will be difficult to stack.

In the present invention, it is preferable that a flexible, non-foamed skin layer made of a polyolefin thermoplastic elastomer is formed on at least one surface of the foamed thermoplastic resin sheet by tRM4.

The above polyolefin thermoplastic nidistomer (hereinafter referred to as TP)
(abbreviated as O) is a partially crosslinked product or blend consisting of a resin phase of polyolefin resin such as ethylene thread polymer or propylene polymer and a rubber phase such as EPDM.As a thermoplastic elastomer, the resin phase is Compared to other thermoplastic elastomers such as styrene threads, phretanes, and esters, it has a low specific gravity, is lightweight, has good weather resistance and cold resistance, and has particularly good heat resistance and extensibility during heat molding, so it can be deep drawn. 1. The above skin R4 may be formed only of TPO, but in order to make the body cheaper and to adjust the physical properties according to the purpose, TPO can be used. If necessary, one type or two or more types of polyolefin resins such as low-density polyethylene, medium-density polyethylene, high-density polyethylene, ethylene-vinyl acetate copolymer, linear low-density polyethylene, and polypropylene are blended. preferable,.

For example, by blending low-density polyethylene or ethylene-vinyl acetate copolymer with TPOK, the heat fusion strength with the thermoplastic resin foam sheet increases, allowing heat fusion at a relatively low temperature, and generally these resins are more durable than other resins. 1. When high-density polyethylene or polypropylene is blended with TPOK, rigidity can be imparted to the laminate, and the shape retention of the molded product can be achieved. You can increase your sexuality. Furthermore, if linear low-density polyethylene is blended with TPO, the tensile strength of the laminate increases, and even when the amount of TPO blended is small, it is possible to compensate for the decrease in deep drawability in vacuum forming or press forming. In this way, the type and amount of resin to be blended can be selected based on the characteristics of each resin and depending on the application.However, in order to ensure good deep drawing formability with Vcy> during molding, It is preferable that the amount of #-tTPO blended is 10% by weight or more, more preferably 20% by weight or more.

Furthermore, inorganic or organic substances such as pigments, flame retardants, antistatic agents, and fillers can be added to the skin layer as necessary.

The thickness Fi (preferably in the range of L 1 - L 5 ynr) of the skin layer is thinner than 0.1 ff, which makes it difficult to stack on the surface of the foam sheet during extrusion, and may cause tearing during or after molding. On the other hand, if the thickness is thicker than tSa+, the weight of the molded product may be large.

In the present invention, the shape of the box made of a laminate of a core material and a thermoplastic resin foam sheet is not particularly limited, such as a cube, a rectangular parallelepiped, a dome shape, a semicylindrical shape, etc.

In the present invention, a laminate is used in which the thermoplastic resin foam sheet is laminated on at least one side of the core material impregnated and cured with a fibrous Ia K thermosetting resin. If the foam sheet is laminated on only one side of the core material, it will be laminated on the outside side of the box. Further, when the skin layer is laminated on only one side of the foam sheet, the core material Vc is laminated so that the skin layer is on the outside.

In the present invention, the lower surface of the box made of the laminate is opened, and the upper surface of the core material constituting the box, that is, the portion of the core material on the upper surface of the box is replaced by the core material on the side surface of the box. The amount of thermosetting resin impregnated is smaller than that of the wood part.

In order to reduce the amount of thermosetting resin impregnated in the upper part of the core material than in the side parts, for example, a fibrous sheet is coated on the convex shape in which the box is formed, and the fibrous sheet is heated. When applying or spraying the curable resin, the thermosetting resin can be applied or sprayed only on the upper surface of the box by applying or spraying the thermosetting resin in a slightly smaller amount than on the side surfaces.

For this reason, K suppresses the supply amount of the thermosetting resin to be coated or sprayed on the upper surface part, or by keeping the supply amount of the thermosetting resin constant and shortening the application time or spraying time. In addition, the fibrous sheet on the top surface has a mesh,
This can also be achieved by masking methods such as covering cloth etc. 3
In addition to the method of adjusting the amount of thermosetting resin supplied to the sheet MC by some means as described above, it is also possible to keep the amount of the resin supplied constant and, on the other hand, to adjust the amount of the thermosetting resin supplied to the fibrous sheet corresponding to the upper surface part. The above objective can also be achieved by reducing the basis weight of the area and reducing the amount of impregnation in that area.

Furthermore, the amount of resin impregnated may be reduced by passing a large number of small holes through the mold and reducing the pressure inside the mold to suck the resin supplied into the mold into the mold. The method of adjusting the amount of thermosetting resin supplied as described above by any means and the method of partially reducing the basis weight of the fibrous sheet may be used together.

In the present invention, the upper surface of the core material constituting the box has a smaller amount of thermosetting resin impregnated than the side surface.
Furthermore, if the weight of the KFi fibrous sheet at the lower side of the core material is increased, or the amount of thermosetting resin is increased to make the amount of resin impregnated larger than other parts, this part in particular can be improved. It is preferable because it is reinforced and will not be destroyed even when used as a vehicle body attachment part.

In order to manufacture the airbag storage case of the present invention, for example, when a split mold consisting of a convex mold and a concave mold is closed, a mold cavity is formed with a gap approximately equal to the thickness of the resin-impregnated fibrous sheet. A fibrous sheet is coated on the convex shape of the mold to be used.
As mentioned above, the fibrous sheet in the area corresponding to the top surface of the box is coated and impregnated with a thermosetting resin so that the amount of impregnation is smaller than in the area corresponding to the side surface, and then molded with a concave shape. The mold is closed, heated and pressurized to harden and cool the resin, and then the mold is opened to remove the molded core material. During this molding, the resin-impregnated fibrous sheet is not compressed in the mold, so a large number of air bubbles are formed that communicate with the front and back surfaces of the resulting core material. Next, the core material is placed in an intake device having an intake hole connected to a vacuum pump, and placed in a hot air oven together with the aforementioned crosslinked foam sheet coated with a hot melt adhesive on one side. When the cross-linked foam sheet has softened, place the foam sheet over the core material and operate the vacuum pump to degas the inside of the core material, and the foam sheet #'i will be adsorbed to the core material and bonded with a hot melt adhesive. It is obtained from K that it is integrated.

In addition to the method of laminating foam sheets by vacuum forming using the core material itself formed in this way as a mold, adhesive is applied to the inner surface of the foam sheet that has been heat-formed in advance so as to follow the outer shape of the core material, and then the core material is laminated with adhesive. It is also possible to layer the material K by covering it.1
[Function] Since the upper surface of the core material has a lower content of thermosetting resin than the side surface, its strength is low and it is easily broken by the expansion of the airbag. Also, the strength of the side parts is high. Since a thermosetting resin is used for the core material, heat resistance is imparted.

The thermoplastic resin foam sheet laminated on the outside of the core material contributes to weight reduction and co-Kl shape, and also provides a desirable appearance and soft feel.

〔Example〕

Hereinafter, uninvented embodiments will be described with reference to the drawings.

FIG. 1 is a perspective view showing one embodiment of a storage case for an airbag according to the present invention, and is a cross-sectional view taken along the line N in FIG. 11 in Figures 1 and 2! Then, lFi bottom surface 1
Reference numeral 4 denotes a sealed box body, which is made of polyethylene with a thickness of 4 ff and a foaming ratio of 20 times, on the outside of a core material 2 of about 5 ff thick, which is made of a fibrous sheet made of felt impregnated and cured with unsaturated polyester resin. A cross-linked foam sheet 3 is adhered and laminated with the present futomelt adhesive, and the foam sheet 3
The outer surface of KFiTPOK is a large blend of low-density polyethylene and high-density polyethylene for flexibility and a thickness of 0.6
The upper surface 111'j of the 1st and 13th box body 1 on which the non-foamed skin layer 4 of H is laminated is a thin walled part cast in a linear or broken line shape to make it easier to break from this part. 1° The amount of thermosetting resin impregnated is smaller in the range a of the upper surface portion 21ij of the core material 2 than in the range b of the side surface portion 22.

This is a 12Fi vehicle body mounting hole.

FIG. 3 is a sectional view showing another flow side of the present invention, in which the amount of resin impregnated in the area approximately a of the upper surface portion 21Vi is smaller than that of the area b of the side surface portion 22, and □ Book interior 13 The fibrous sheet of the fractured part 4 along the line has a lower basis weight than other parts, and the outer lower part of the side part 22 of the core material 2 has #
The embodiment is the same as the embodiment shown in FIG. 1, except that another fibrous sheet) K, a reinforcing sheet impregnated with a thermosetting resin, and sheet 3 are joined.

FIG. 4 is a sectional view showing still another embodiment of the present invention.
H
13' is a thin wall portion provided in the foamed sheet 5, and is provided along the thin wall portion 13 to make it easier to break.

[Effects of Origin 1] Since the airbag storage case of the present invention has the above-described structure, the strength of the upper surface and the side surface of the storage case is uneven, and the strength of the upper surface is higher than that of the side surface. Since the strength is lower than
When the gas generator is operated and the airbag is inflated, the pressure easily breaks the upper surface of the storage case, and the airbag can very easily pop out of the storage case.

In addition, it has the advantage of being able to freely design the basis weight of the fibrous sheet, the reinforcement of the thermosetting resin, etc. 3. Also, since thermosetting resin is used for the core material, it has excellent heat resistance, and the interior of the car can reach high temperatures. It will not deform even if

Furthermore, since thermoplastic resin foam sheets are laminated on at least the outside of the core material, the storage case has a good appearance, a soft feel, and is lightweight.

The airbag storage case of the present invention does not require large-scale manufacturing equipment, and can be manufactured with a large ftK at low cost using simple equipment.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing one embodiment of the airbag storage case of the present invention, Fig. 2 is a cross-sectional view taken along the Rolo line in Fig. 1, and Fig. 3 is a perspective view of another embodiment of the present invention. The cross-sectional view @4 is a cross-sectional view showing still another embodiment of the present invention. 1: Box body, 14: Bottom surface, 2: Core material, 21: Top surface portion, 22: Side surface portion, 3.5: Thermoplastic resin foam sheet.

Claims (1)

[Claims] 1. A box made of a laminate in which a thermoplastic resin foam sheet is laminated on at least one side of a core material made of a fibrous sheet impregnated and cured with a thermosetting resin, the lower surface of the box being open; An airbag storage case characterized in that the upper surface part of the core material constituting the box body has a smaller amount of thermosetting resin impregnated than the side part.