JPS6345287B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (1) Field of the Invention The present invention relates to a method for molding an automobile interior material formed by laminating a core material, a foam layer, and a skin layer.

(2) Prior art and its problems There are three types of molding methods for automobile interior materials that have this type of foam layer in the middle: (A) welding method, (B) vacuum method, and (C) foaming method. The construction method is known.

The above (A) welding method is a method mainly for forming flat interior materials, in which an open-cell low-density foamed urethane slab material is laminated on a core material, and the surface of this slab material is coated with chloride. Skin materials such as vinyl are laminated, and this is placed in a welder mold to form a welder groove pattern on the surface, and the three parts are fixed together through the welded part, that is, the welder groove pattern part. It was designed to do so.

(B) In the case of the Baquium construction method, the foam layer and skin material are laminated in advance in order to attach the foam layer and skin material along the curved surface of the core material, which has been preformed into the required three-dimensional curved surface. This laminated product is molded by vacuum suction to match the curved shape of the core material, and is adhered onto the core material via an adhesive.

Furthermore, in the (C) foaming method, unfoamed resin is injected between the core material, which has been previously molded into the required curved surface, and the skin material, and then this is foamed in the mold between the core material and the skin material. In this method, the above-mentioned skin material is a baculum-shaped skin or a spray skin in which a coating film-like skin is previously formed on the surface of the mold by spraying or the like.

However, in the method (A) above, the foam layer interposed between the core material and the skin material enables welding between the core material and the skin material.
The thickness is extremely thin, and only open-cell, low-specific-gravity materials can be used, and the finished product has poor cushioning properties, lacks firmness, easily collapses, and lacks overall tension, resulting in an unsightly appearance. The problem with the welding method is that the uneven shape of the product surface is only formed by the compressive recovery force of the foam layer corresponding to the part crushed by the welding process. However, there are problems such as the fact that the curved surface of that part cannot be arbitrarily set.

In addition, in method (B), since the pre-laminated product of the skin material and cushion material is vacuum-formed into the curved shape of the core material, both the foam layer and the skin material are stretched in response to the vacuum suction. I got lost,
The thickness of the cushion material is thinner than the original fabric, and this material also lacks cushioning properties after processing. In addition, since this method uses a laminated skin, when it is pasted to the core material and its edges are wrapped around the back side of the core material, the thickness of this part is reduced by the foam layer. This results in a large dimensional error when assembling it to the car body, so it is necessary to peel off the pad material from the folded end part and then wrap it around the back side. This causes a lot of man-hours.

Furthermore, in method (C), if a spray skin layer or the like is used as the skin material, this molding method itself involves a wet manufacturing process, which not only causes pollution of the working environment, but also extremely high raw material costs. It is expensive, requires many molds such as metal molds or silicone molds, and has drawbacks such as extremely long cycle time for molding, and for this reason, it is only used for relatively high-grade products.

(3) Purpose of the Invention The purpose of the present invention is to enable molding of this type of foam interior material with a three-layer structure by press molding, and to prevent cell destruction and loss of elasticity of the foam material as described above during press molding. This was done to prevent such incidents from occurring.

(4) Structure and Effects of the Invention In order to achieve the above object, the present invention provides an interior material for an automobile, which is formed by laminating a foam layer and a skin layer on the surface of a core material formed into a desired molded product shape. , A foamable resin sheet of a required thickness made of a sheet-like extrusion molded product containing a foaming agent is used as the material constituting the foam layer, and this foamable resin sheet is heated above its melting point to plasticize it, and at the same time, a foaming reaction is caused. Under this foaming state, it is laminated together with the core material and skin material on the mold surface of the cold press lower mold,
After that, a cold press upper mold with a required mold surface carved thereon is lowered and engaged with the lower mold, and the skin material and the foamable resin sheet are compressed to match the mold surface shape of the upper mold, Moreover, the compressed end is welded onto the core material, internally foamed, and then, after cooling, the upper mold is separated from the lower mold.

By the above method, the present invention has the advantage of the press molding method that an arbitrary shape can be obtained along the mold surface, and a desired molded product can be obtained with a single molding process. Even if you want to create different parts, you can do it easily, and if you use vinyl chloride as the surface material, the grain on the surface will not disappear, and it is comparable to the most high-class conventional foaming method. You can get the appearance performance that you want.

In other words, before foaming, some thermoplastic foam resin sheets are extruded into a sheet shape and contain a foaming agent inside, and by putting it in a heating furnace, the sheet can be heated As the plastic resin is heated and plasticized, foaming is started by the action of the foaming agent, resulting in a foamed resin sheet with the required thickness, which is usually used as a primary product for secondary processing. However, in the present invention, by heating unfoamed resin having such characteristics in advance and foaming it in the mold by cold press molding, it is possible to obtain a foamed product corresponding to the cavity thickness of the mold, and This is integrated with a skin material and a core material.

(5) Description of Examples First, regarding the materials, conventional materials cannot be used for the core material and the skin material.

For example, in the case where the interior material is made of a flat plate, the core material may be pressboard trimmed to fit the shape of the vehicle body panel;
Alternatively, this pressboard can be combined with metal parts. In addition, when molding into a curved surface, the outer periphery of a material suitable for molding along the curved shape, such as a synthetic resin board or a composite resin board containing wood powder, is trimmed in advance by press molding in a separate process. Additionally, a material having a required curved shape formed on the surface can be used.

Next, as the skin material, a vinyl chloride skin with a textured surface is used as the most common material. In addition, decorative sheets such as nonwoven fabrics or carpets, and combinations of these vinyl chloride skins, nonwoven fabrics, and carpets can also be used.

An adhesive may be applied or a hot melt film may be interposed on the bonding surfaces of the skin material and the core material with the foam layer to improve the adhesion with the foam layer.

Next, the above-mentioned thermoplastic foamable resin sheet is used as the constituent material of the foam layer. More specifically, this foamable resin sheet is made by mixing an appropriate amount of azohexahydrobenzonitrile as a blowing agent into polyethylene and ethylene vinyl acetate as a base resin, and adding a small amount of an initiator and other additives and kneading them. Examples include those extruded into a sheet at a temperature below the foaming start temperature.

A molding method using each of the above-mentioned materials will be explained below with reference to the drawings.

(A) First, each of the above-mentioned materials is trim-cut in advance to an outer shape corresponding to the shape of the molded product, and if the core material is required to have a curved surface shape, press molding is first performed.

(B) Next, the unfoamed thermoplastic resin sheet 3 thus trim-cut is placed into an infrared heater device 10 as shown in FIG. 1, and heated to a temperature higher than the melting temperature of the base resin inside.

By this heating, the base resin of the resin sheet 3 is plasticized, and at the same time, the temperature of the foaming agent contained therein is raised above its foaming start temperature, and as a result, the resin sheet 3 is in the state shown by the imaginary line in the thickness direction. swells into

(C) Next, as shown in FIG. 2, the above-mentioned core material 2 is placed on the mold surface 1a of the cold press lower mold 1, and on the upper part of this core material 2, the foamed material which has been heat-plasticized and expanded as described above is placed. A foamable resin sheet 3 is laminated, and a skin material 4 is further placed on top of the foamable resin sheet 3.
Set it up.

(D) From this state, immediately engage the cold press upper die 5 onto the lower die 1.

A mold surface for configuring the surface of the molded product, that is, an uneven surface 5a is formed on the lower surface of the upper mold 5, and as shown in FIG. Resin sheet 3
Both are compressively deformed along the shape of the mold surface.

FIG. 4 shows the main part of the resin sheet 3. In the initial stage of engagement with the upper mold, the resin sheet 3 remains in an expanded state, and due to the foaming pressure, it conforms to the shape of the uneven surface 5a of the upper mold 5. Accordingly, the cells (bubbles) that were once formed due to expansion in the part where the skin material 4 is compressed together with the skin material 4 and has no clearance with the mold surface 5a move to the part where there is a gap as shown by the arrow, and the heated and melted resin sheet 3 The skin material 4 and the core material 1 are directly bonded to each other via a resin component, a hot melt sheet provided on the bonding surface of the skin material 4 and the core material 1, or an adhesive.

Further, in this state, since the surface of the skin material 4 is not heated in any way by the mold surface of the upper mold, the grains formed on the surface will not disappear.

(E) Then, over time, the resin sheet 3
is solidified in a foamed state, and as a result, a molded product in which each part is integrated can be molded in a mold. After cooling is completed in this manner, the upper mold 5 is separated from the lower mold, and the product is demolded.

In this state, the resin sheet 3 is cooled and solidified while maintaining the expansion ratio corresponding to the cavity thickness, and is maintained in a shape corresponding to the compression ratio.

Therefore, the automobile interior material constructed in this way can be molded into a curved surface that corresponds to the mold surface of the cold press mold, and its elasticity is determined by the thickness of the unfoamed resin sheet material relative to the cavity thickness. It can be set variably according to the thickness ratio, and the surface feel can be obtained according to that ratio, so it is cheaper than the conventional construction method using high-density urethane foam, and has the same cushioning properties. In addition, because the so-called cushioning properties change depending on the compression ratio of the mold, it is possible to change the feel locally using the same process and the same material, thereby reducing the number of man-hours. and can be done inexpensively.

[Brief explanation of drawings]

1 to 3 are explanatory sectional views showing the molding method according to the present invention, and FIG. 4 is an enlarged sectional view of section A in FIG. 3. 1... Cold press lower mold, 1a... Mold surface, 2
... core material, 3 ... foamable resin sheet, 4 ... skin material, 5 ... cold press upper mold, 5a ... mold surface,
10...Infrared heater device.

Claims (1)

[Scope of Claims] 1. An interior material for an automobile formed by laminating a foam layer and a skin layer on the surface of a core material formed into a desired molded product shape, wherein the material constituting the foam layer contains a foaming agent. Using a foamable resin sheet of a required thickness made of a sheet-like extrusion molded product, this foamable resin sheet is heated above its melting point to plasticize it and induce a foaming reaction. Laminated with core material and skin material on the mold surface,
After that, a cold press upper mold with a required mold surface carved thereon is lowered and engaged with the lower mold, and the skin material and the foamable resin sheet are compressed to match the mold surface shape of the upper mold, A method for molding an interior material for an automobile, characterized in that the compressed end is welded onto a core material, foamed internally, and then, after cooling, the upper mold is separated from the lower mold.