JPH0596997A - Manufacture of hot flow mold having hinge structure - Google Patents

Abstract

PURPOSE:To obtain a hot flow mold which has hinge structure whose bending performance and durability at a hinge part is excellent by casting a molted resin in a lower die provided with a projection part forming a notch in the groove state, mounting a surface material on it and putting an upper die to close them and by pushing and cutting the molten resin at the projection part. CONSTITUTION:A hot flow mold is constituted of a backup resin layer 1 and a porous surface layer 2 integrally laminated on it and has a hinge part 3 in which a notch 4 in the groove state is formed integrally on the back of the resin layer 1. A lower die 32 provided with a projection part 32 to produce the notch 4 in the groove state is used as a hot flow forming die, a molten resin 34 to be the resin layer 1 is cast in the lower die 32, a surface material 35 constituting the surface layer 2 is mounted on it, and an upper die 31 is put together and closed for forming. At this time, the molten resin 34 is pushed and cut at the projection part 33 to obtain a mold in which a layer substantially made only of the resin does not exist at the bottom of the notch 4 in the groove state.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a hot flow molded product having a hinge structure.

[0002]

2. Description of the Related Art A molded article integrally formed with a hinge structure is, for example, a rear parcel used in an automobile as described in Japanese Utility Model Publication No. 57-199149.

A rear parcel in an automobile is a thin plate-like member which is provided so as to be rotatable and removable so as to cover an upper portion of a luggage compartment between a rear seat and a back door of the automobile.

FIG. 4 is a perspective view of the rear parcel described in the above publication, and FIG. 5 is an enlarged sectional view of a hinge structure portion thereof.

4 to 5, reference numeral 21 is a backup resin layer such as polypropylene resin, and a skin layer 22 is integrally laminated on the resin layer. Reference numeral 23 is a hinge portion, and in the hinge portion 23, a thin portion 24 is formed on the resin layer 21. The rear parcel is divided into two parts, a front part A and a rear part B, by the hinge part 23, and the front part A and the rear part B can be opened and closed relatively.

When a molded product having the hinge structure as described above is to be molded, it is conceivable to carry out hot flow molding as shown in FIG. In FIG. 6, 31 is an upper mold and 32 is a lower mold. The lower die 32 has a thin part 24 of the hinge part.
Is provided with a convex portion 33. Extruded molten resin 34 such as polypropylene resin with an extruder
Pour into 32 and put the skin material 35 on it. Next lower mold
The upper mold 31 is matched with 32, the mold is closed, and the molten resin is further poured into a necessary portion, and after cooling, the mold is opened and the molded product is taken out.

[0007]

However, in the hinge structure of the rear parcel, since the thin resin portion 24 is present below the skin layer 22, the flexibility of the hinge portion is not sufficient, and the hinge portion is opened and closed. There is a problem that cracks occur in the thin portion during repeated operation, which damages the skin layer in this portion and impairs the hinge function.

An object of the present invention is to solve the above-mentioned problems and to provide a method for producing a hot-flow molded article having a hinge structure in which the hinge portion has both excellent flexibility and durability.

[0009]

According to the present invention, a backup resin layer and a porous skin layer integrally laminated thereon are provided, and a groove-shaped notch is integrally formed on the back surface side of the resin layer. When manufacturing a hot-flow molded product having a hinge structure formed as a hinge part, the lower mold of the hot-flow mold is provided with a convex part for forming the groove-shaped notch, The molten resin to be the resin layer is poured into the lower mold, the skin material that constitutes the skin layer is placed on the lower mold, and the upper mold is combined to mold and mold, and the molten resin is formed at the convex portions during molding. The present invention relates to a method for producing a hot-flow molded product having a hinge structure, which is characterized in that a molded product in which a layer made only of a resin does not substantially exist at the bottom of the groove-shaped notch is pressed.

[0010]

The present invention will be described below with reference to the drawings.

FIG. 1 is a partial sectional view showing an embodiment of a hinge structure in a hot flow molded product obtained by the method of the present invention.

In FIG. 1, 1 is a backup resin layer,
2 is a porous skin layer, and the resin layer 1 and the skin layer 2 are integrally laminated by hot flow molding.

Reference numeral 3 is a hinge portion, and in the hinge portion 3, a notch portion 4 is formed in the resin layer 1.

In the present invention, when the hot flow molded product having the hinge structure as described above is formed, the notch 4 is formed.
It was found that it is important that there is no thin portion of the resin layer at the bottom of the resin layer as in the conventional example.

Further, in the present invention, the width d of the bottom portion of the cutout portion 4 is in the range of 0.5 to 3 mm, and the angle θ formed by the resin end surface 5 in the cutout portion 4 with the joint surface between the resin layer 1 and the skin layer 2. It has been found to be important that is in the range of 30-80 degrees.

As described above, the skin layer 2 in the hinge portion
If the resin-only layer is present underneath, the flexibility of the hinge portion is impaired and cracks are likely to occur.

However, in the present invention, since the resin layer does not exist below the skin layer 2 in the hinge portion, the hinge portion is excellent in flexibility and does not cause defects such as cracks.

In the present invention, it is preferable to define the width d and the angle θ within the specific range as described above in order to prevent formation of a layer made of only the resin in the hinge portion 3.

In order to prevent the resin-only layer from existing below the skin layer 2 of the hinge portion, the space between the upper surface of the convex portion 33 of the lower mold 32 and the skin material 35 is set at the time of mold closing in hot flow molding. It is necessary to push out the molten resin 34 existing in 1) by the convex portion 33.

In the present invention, by setting the angle θ in the range of 30 to 80 degrees, that is, by setting the angle of the inclined surface of the convex portion 33 of the lower mold 32 within the above range, the convex portion when the mold is closed. It was found that the molten resin was pushed off by 33, and in the resulting molded product, the resin-only layer did not exist below the skin material 2 of the hinge portion. However, if the angle θ is out of the above range, it is difficult to push the molten resin off, and a layer of only the resin is formed at the site, which is not preferable.

It is important that the skin layer 2 in the hinge portion is appropriately impregnated with resin to achieve the reinforcing effect.

From this viewpoint, the width d in the hinge portion is
Is too wide, that is, if the width of the upper end of the convex portion 33 of the lower mold 32 is too wide, it becomes difficult to cut off the molten resin described above, and there is a tendency that a resin-only layer is formed at the site as well. Since the amount of the molten resin remaining in the upper portion of the portion 33 is large, the amount of the molten resin impregnated into the skin material causes excessive impregnation, which tends to exude to the surface of the skin material, resulting in poor appearance.

On the other hand, if the width d is too narrow, as shown in FIG. 2 (in the extreme case of width d = 0 in FIG. 2), although the molten resin is cut off, most of the resin is left on the skin material. Since it is not impregnated, it is difficult to obtain a reinforcing effect, and since the width of the bent portion of the hinge portion is narrow, the bendability is poor, and the risk of cracking due to the notch effect increases. When the notch 4 of the hinge portion shown in FIG. 3 has an arcuate cross section, the same problem as in the hinge structure shown in FIG. 2 occurs.

From the above point of view, in the present invention, by setting the width d to 0.5 to 3 mm, only the portion 6 corresponding to the hinge of the skin layer 2 is appropriately impregnated with the resin, and the flexibility and durability are good. There is also a hinge structure with a good appearance.

In the present invention, as the resin used for forming the resin layer 1, for example, polyolefin resins such as polypropylene, polyethylene, ethylene-propylene copolymer, and blends of these with rubber can be appropriately used.

The porous skin material used for forming the skin layer 2 is not particularly limited as long as it can be impregnated with a resin and has good bending resistance, and for example, a nonwoven fabric, a knit or the like can be appropriately used.

The method of the present invention is not limited to the above-mentioned rear parcel in an automobile, and any hot flow molded article including a skin layer having a hinge structure and a backup resin layer can be applied.

[0028]

EFFECTS OF THE INVENTION With the above structure, in a hot-flow molded product having a hinge structure and comprising a skin layer and a backup resin layer, a hinge structure having a good bendability at the hinge portion and excellent durability can be obtained.

[Brief description of drawings]

FIG. 1 is a partial sectional view showing an embodiment of a hot-flow molded product having a hinge structure obtained by the method of the present invention.

FIG. 2 is a partial cross-sectional view showing a hinge structure outside the scope of the present invention.

FIG. 3 is a partial cross-sectional view showing a hinge structure outside the scope of the present invention.

FIG. 4 is a perspective view showing a molded product having a conventional hinge structure.

5 is a partially enlarged sectional view showing a hinge portion of the molded product shown in FIG.

FIG. 6 is an explanatory diagram of a hot flow molding method.

[Explanation of symbols]

 1 Backup resin layer 2 Skin layer 3 Hinge part 4 Notch part d Width θ angle

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location B32B 3/02 6617-4F B29L 31:22 4F

Claims (1)

[Claims] 1 has a back-up resin layer and a porous skin layer integrally laminated thereon, and has a hinge structure in which a groove-shaped notch is integrally formed on the back surface side of the resin layer to serve as a hinge portion. When manufacturing a hot-flow molded article, a hot-flow molding die having a convex portion for forming the groove-shaped notch is used as a lower die, and a molten resin to be the resin layer is poured into the lower die. , On which the skin material constituting the skin layer is placed, the upper mold is joined and molded by binding, and the molten resin is pushed out by the convex portion at the time of molding, and substantially at the bottom of the groove-shaped cutout portion. A method for producing a hot-flow molded product having a hinge structure, which is characterized in that a molded product free of a layer consisting of only a resin is obtained.