JPH11227542A - Skin for vehicular interior trim and airbag door structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To progress the expansion of an airbag smoothly and surely and dissolve the drop of an appearance quality by forming a multi-layer structure consisting of an other layer with a specific tensile elongation and an inner layer, integrally piled on the inside surface of this outer layer, whose tensile elongation is higher than that of the outer layer and giving a brittle part to the inner layer. SOLUTION: An instrument panel is composed of a base material 1 made of polypropylene, a foaming body layer 2 consisting of a polyurethane foaming body piled on the surface of the base material 1 and a skin 3 piled on the surface of the foaming body layer 2. On the inner layer 31, a H-shaped slit (brittle part) 32 is formed on a position corresponding to a slit 10 and the foaming body layer 2 is filled in the slit 32. When a big tensile stress is exerted on the inner layer at the airbag expansion time, the inner layer is cleaved easily at the brittle part 32. When a force is transmitted to the outer layer, as the tensile elongation of the outer layer is low like 70 to 170%, the inner layer is broken easily at the position of the brittle part 32. Thereby, the airbag is expanded in a car room.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a skin used on a surface of a vehicle interior component containing an airbag and a structure of an airbag door using the skin.

[0002]

2. Description of the Related Art In recent years, airbags have been used in automobiles in order to cope with traffic accidents caused by an increase in traffic volume and to improve occupant safety. For example, an airbag for a driver is housed in a steering wheel, inflated by the generation of gas due to an impact at the time of a collision, and deployed in a vehicle cabin, thereby preventing the driver from colliding with the steering and windshield. An airbag is also stored on the back side of the instrument panel to prevent a passenger in the passenger seat from colliding with the instrument panel and the windshield. Furthermore, in recent years, it has been recommended that an airbag be provided on the back side of the door trim so that a collision from the side can be dealt with.

[0003] Instrument panels and door trims are generally composed of a resin base material and a skin.
In order to maintain the shape, a substrate having high rigidity is used. However, when an airbag is arranged on the back side of the interior component, various measures have been taken because the rigidity of the base material hinders smooth expansion of the airbag upon impact.

For example, when an airbag is housed on the back side of an instrument panel or door trim, an opening for deploying the airbag is provided in the base material, and an airbag door covering the opening is provided in order to maintain the appearance quality. That is being done. If the interior component and the airbag are separated as described above, the resin base material of the interior component does not hinder deployment of the airbag in the vehicle interior. However, in this case, the boundary with the airbag door is exposed on the surface of the interior product, so considering the appearance quality and strength quality of the interior product, the airbag door may be integrated with the interior product body. desirable.
However, if the airbag is integrated, it will hinder the deployment of the airbag into the vehicle interior. Therefore, in order to deploy the airbag instantaneously upon impact, it is desirable that the bonding strength between the airbag door and the interior component body be as low as possible.

In order to solve this contradiction, conventionally, a fragile portion such as a slit or a slit is formed on the surface of a resin base material of an interior product, and the surface is covered with a soft skin to form an airbag door. Has been done. With this configuration, the rigidity and appearance quality of the interior components are ensured in normal times, and when the airbag is inflated, the fragile portion and the skin are broken by the force of the inflation to open the airbag door, and the vehicle of the airbag is inflated. It can be deployed indoors.

As such an interior product, for example, Japanese Patent Application Laid-Open
No. 202550 discloses an airbag cover comprising a core layer made of a hard resin and a soft skin layer integrally formed on the surface of the core layer, and having an H-shaped or cross-shaped slit in the core layer. It has been disclosed. In addition, JP-A-5-294196
The publication consists of a hard core layer and a soft skin layer,
An airbag storage cover body provided with a slit on the back side of a core layer is disclosed.

In the interior parts (covers) disclosed in these publications, the rigidity of the interior parts is ensured by the core layer in normal times, and an excellent tactile sensation is obtained by the skin layer. Since the slits and the slits become fragile portions, the cover is opened along the slits and the slits by the inflation force of the airbag at the time of impact, so that the deployment of the airbag into the vehicle interior is allowed.

[0008]

A vehicle interior component such as an instrument panel or a door trim has a hard resin base material, a foam layer such as urethane foam laminated on the base material surface, and a foam layer surface. It is composed of a laminated skin made of polyvinyl chloride or the like. The rigidity of the base material maintains the shape, the foam layer improves the tactile sensation, and the skin improves the appearance quality and further improves the tactile sensation.

However, in the case where a fragile portion is provided on the base material of such an instrument panel and the portion is used as an airbag door, the airbag door is not opened due to the stiffness of the skin, making it difficult to deploy the airbag. There is fear. In particular, the skin formed by powder slush molding or the like has a large thickness, which is likely to cause this problem. Therefore, a fragile portion is formed on the base material, and a concave portion is formed on the back side of the skin, for example, at a position corresponding to the fragile portion of the base material. If the material of the skin is polyvinyl chloride, if the thickness of the recess is 0.3 mm or less, when the base material ruptures from the fragile portion when the airbag is inflated, the skin will also easily rupture in the recess by the force. The deployment of the airbag into the passenger compartment is allowed.

However, in order to form a concave portion on the back surface side of the skin, for example, as described in Japanese Patent Application Laid-Open No. HEI 4-153345, a hot blade or a high-frequency welder is used. Since this is a post-processing step after the formation, the number of steps is increased and there is a problem in cost. In order to avoid such a problem, for example, as disclosed in Japanese Patent Application Laid-Open No. 7-309188, it is conceivable to form a concave portion when molding the skin. However, in the case of powder slush molding, it is extremely difficult to precisely control and control the thickness to 0.3 mm or less.

Even if this problem is solved by improving the molding method, the thickness of the polyvinyl chloride skin is reduced.
When the thickness is reduced to 0.3 mm or less, the weather resistance and the durability are extremely reduced, and there is a problem that the appearance of the surface of the concave portion becomes different from the other portions with the passage of time, and the appearance quality is deteriorated. The present invention has been made in view of such circumstances, and an object of the present invention is to provide an airbag door in which the deployment of an airbag proceeds smoothly and reliably, and which is inexpensive and has no deterioration in appearance quality.

[0012]

According to a first aspect of the present invention, there is provided a vehicle interior part skin having a resin base material and an airbag housed on the back side. The skin to be coated, with a tensile elongation of 70 to 170%
A multilayer structure comprising an outer layer and an inner layer integrally laminated on the inner surface of the outer layer and having a higher tensile elongation than the outer layer, and having a fragile portion in the inner layer.

A feature of the airbag door structure according to claim 2 which solves the above-mentioned problem is that a resin base material having a fragile portion disposed on the surface of the stored airbag and a foam laminated on the surface of the base material are provided. The outer layer has a tensile elongation of 70 to 170%, and the inner layer has a higher tensile elongation than the outer layer. A multilayer structure is formed in which the inner layer is laminated on the surface of the foam layer and a fragile portion is formed in the inner layer.

[0014]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, the tensile elongation is 70 to 1
A multilayer structure consisting of an outer layer of 70% and an inner layer that is integrally laminated on the inner surface of the outer layer and has a higher tensile elongation than the outer layer,
An epidermis with a fragile portion formed in the inner layer is used. Therefore, when a large tensile stress acts on the inner layer during deployment of the airbag, the inner layer is easily split at the fragile portion. When the force is transmitted to the outer layer, the outer layer has a low tensile elongation of 70 to 170%, so that even if the outer layer is as thick as about 0.8 mm, it easily breaks at the position of the weak portion of the inner layer. This allows the airbag to be deployed in the vehicle interior.

[0015] When the tensile elongation of the outer layer exceeds 170%, it becomes difficult to break the airbag during deployment. Also 70%
If it is less than 1, the heat resistance is extremely reduced. Therefore, in the present invention, the tensile elongation of the outer layer is set to 70 to 170%. On the other hand, in a normal state, the outer layer has no fragile portion, and thus has excellent appearance quality. Further, since the inner layer has a sufficient strength, the physical properties at normal times are satisfied. Further, since the deployment of the airbag is not hindered even if the thickness of the outer layer is as thick as about 0.8 mm, the weather resistance and durability are satisfied even when polyvinyl chloride is used as the material of the skin.

The inner layer and the outer layer can be continuously formed by using the powder slush molding method, and the fragile portion can be formed simultaneously with the formation of the inner layer. Therefore, an inexpensive skin can be obtained without an increase in steps. As the material of the inner layer and the outer layer, resin materials such as polyvinyl chloride, thermoplastic urethane, and thermoplastic olefin can be used. FIG. 4 shows the difference in tensile elongation between polyvinyl chloride and thermoplastic urethane. FIG. 4 shows the change in the tensile elongation when the sample formed at a predetermined thickness was treated at a temperature of 110 ° C. for 1200 hours and 2400 hours. As shown in FIG. 4, it can be seen that the change shows the same tendency even if the initial tensile elongation is different if the material is the same. In addition, since the tensile elongation of polyvinyl chloride significantly decreases after thermal history, it is understood that it is preferable to use thermoplastic urethane when heat resistance is important.

Further, the thermoplastic urethane has a thickness of 0.4 to
Even if it is 0.5 mm, it can be broken by the force of inflation of the airbag. Therefore, since the control and control of the thickness of the outer layer becomes easy, the powder slush molding method can be used, and the skin can be manufactured at low cost. The inner layer and the outer layer of the skin may be made of the same material or different materials. The tensile elongation of the inner layer is not particularly limited as long as it is higher than that of the outer layer.
It is desirable to make the above.

As the resin base material, a hard resin such as polypropylene, polyethylene, nylon, AS resin, or a mixture of these resins with a reinforcing material such as glass fiber is used. Various selections are used. As a molding method, an injection molding method, a stamping molding method, or the like can be used. The fragile portion formed in the inner layer of the base material and the skin can be selected from a groove, a concave portion, a slit, a through hole, and the like. The shape of the fragile portion can be, for example, a square shape, a U shape, an H shape, a cross shape, or the like, and the fragile portion of the base material and the fragile portion of the inner layer of the skin coincide with each other at the same position. Or a different shape.

To form the airbag door structure of the present invention, first, a base material is formed by injection molding or the like, and a skin is formed by powder slush molding or the like. To form the skin, for example, double powder slush molding is used, and the outer layer is first molded. The design surface is the surface in contact with the mold surface, and then the inner layer is formed on the inner surface of the outer layer exposed in the mold. If the jig is in contact with the outer layer surface when forming the inner layer, the inner layer will not be formed on the surface where the jig abuts,
The portion can be a weak portion, and the weak portion can be formed simultaneously with the formation of the inner layer.

The preformed base material and the skin are placed in a foaming mold, and the urethane foam resin is foamed between the base material and the skin, thereby forming a foam integrated with the skin and the base material. A body layer can be formed.

[0021]

The present invention will be described below in detail with reference to examples. In this embodiment, the present invention is applied to an instrument panel of an automobile and its skin. FIG. 1 is a sectional view of a main part of an airbag door portion of an instrument panel according to the present embodiment. The instrument panel includes a polypropylene base material 1, a foam layer 2 made of polyurethane foam laminated on the surface of the base material 1, and a skin 3 laminated on the surface of the foam layer 2. I have.

An H-shaped slit 10 is formed in the substrate 1, and an airbag housing is provided below the slit 10. The outer skin 3 is made of thermoplastic urethane and has an outer layer 30 having a tensile elongation of 150% and a thickness of 0.5 mm, and a thermoplastic urethane laminated integrally on the inner surface of the outer layer 30 and having a tensile elongation of 300% and a thickness of 300%. An inner layer 31 of 0.5 mm is formed, and the inner layer 31 is integrally laminated on the surface of the foam layer 2. In the inner layer 31, an H-shaped slit 32 is formed at a position corresponding to the slit 10, and the foam layer 2 fills the inside of the slit 32.

This instrument panel was manufactured as follows. First, the substrate 1 is formed by injection molding. The slit 10 is formed simultaneously with the molding of the substrate 1. On the other hand, the skin 3 is formed separately from the formation of the base material 1. 2 and 3 show a method of manufacturing the skin 3. FIG. The first powder box 4 contains a first powder 40 made of thermoplastic urethane having a tensile elongation of 150%, and the first powder 40 and a second powder 40 described later.
The mold 5 heated above the melting point of the powder 60 is fixed to the first powder box 4 so as to close the opening. And the first powder box 4 and the mold 5
The first powder 40 adheres to the mold surface of the mold 5 and melts, and the first powder 40 adheres to the mold surface of the mold 5.
A molten layer 41 is formed.

Next, the mold 5 having the first molten layer 41 adhered to the mold surface is fixed to the second powder box 6. The second powder box 6 contains a second powder 60 made of thermoplastic urethane having a tensile elongation of 300%. From the bottom of the second powder box 6, partition plates 61, 62 arranged so as to have an H-shaped cross section project, and when the mold 5 is fixed, the tips of the partition plates 61, 62 become the first molten layer 41. It is constituted so that it may contact the surface of.

By rotating the second powder box 6 and the mold 5 together, the second powder 60 adheres to the surface of the first molten layer 41 and melts, and the ends of the partition plates 61 and 62 come into contact. The second molten layer 63 is formed on the surface of the first molten layer 41 except for the portion where the melting has occurred. Then, by removing the mold 5 from the second powder box 6 and cooling, the first molten layer 41 and the second molten layer 63 are solidified, and the skin 3 having the outer layer 30 and the inner layer 31 and having the slit 32 on the surface of the inner layer 31 is formed. It is formed. By forming a grain pattern or the like on the mold surface of the mold 5, the grain pattern is transferred to the surface of the outer layer 30, and the skin 3 having a high design property is formed.

The skin 3 released from the mold 5 is arranged on one mold surface of a foaming mold (not shown) so that the outer layer 30 contacts the mold surface. The substrate 1 is arranged on the other mold surface of a foaming mold (not shown). Then, by injecting a urethane foam resin between the base material 1 and the skin 3, and performing foam molding,
The foam layer 2 integrally formed with the base material 1 and the skin 3 is formed, and an instrument panel is manufactured.

In this instrument panel, the skin 3
Since only the outer layer 30 is exposed on the design surface of the
Is not exposed and has excellent appearance quality and tactile sensation. Also inner layer 31
Accordingly, the epidermis 3 usually shows a sufficient strength. Then, when the airbag disposed below the slit 10 of the base material 1 is inflated at the time of impact, the base material 1 is torn at the slit 10 by the force of the expansion and swings toward the foam layer 2 side. The force is transmitted to the foam layer 2, and the tensile elongation of the foam layer 2 is 30 to 40%.
Therefore, the foam layer 2 is cleaved along the slit 10. This force is further transmitted to the skin 3, but the inner layer 31 has a high tensile elongation, so that the general portion does not cleave, and the slit 32
Try to cleave with. Since the outer layer 30 has a low tensile elongation, stress concentration occurs at a portion along the slit 32 and the outer layer 30
30 cleaves at that point.

As a result, the instrument panel is torn in an H-shape and the airbag door is opened, so that the airbag can be deployed in the vehicle interior.

[0029]

That is, according to the skin and the airbag door structure of the present invention, the airbag door can be reliably torn at the time of impact while maintaining the appearance quality and the strength at the normal time as usual. Can be. Further, the number of man-hours for manufacturing the skin can be reduced, and the cost can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view of a main part showing an airbag door portion of an instrument panel according to an embodiment of the present invention.

FIG. 2 is an explanatory cross-sectional view showing a state in which an outer layer of a skin is formed in one embodiment of the present invention.

FIG. 3 is an explanatory cross-sectional view showing a state in which an inner layer of a skin is being formed in one embodiment of the present invention.

FIG. 4 is a graph showing the relationship between the heating holding time at 110 ° C. and the tensile elongation.

[Explanation of symbols]

1: base material 2: foam layer
3: epidermis 30: outer layer 31: inner layer 3
2: Slit (fragile part)

Claims (2)

[Claims] 1. An outer layer having a resin base material and coated on the surface of a vehicle interior component in which an airbag is housed on the back side, the outer layer having a tensile elongation of 70 to 170%, and the inner surface of the outer layer. A skin for a vehicle interior product, which has a multilayer structure composed of an inner layer integrally laminated with the inner layer and having a higher tensile elongation than the outer layer, and having a fragile portion in the inner layer. 2. A resin base material having a fragile portion disposed on a surface of a stored airbag, a foam layer laminated on the surface of the base material, and a skin layer laminated on the surface of the foam layer. ,
The skin has a multilayer structure comprising an outer layer having a tensile elongation of 70 to 170% and an inner layer having a higher tensile elongation than the outer layer, which is integrally laminated on the inner surface of the outer layer. An airbag door structure characterized in that a fragile portion is formed in the inner layer and the inner layer is laminated.