JPH0490313A - Method for in-mold molding - Google Patents

Abstract

PURPOSE:To prevent a foamed layer from receiving damage due to the heat of an injected resin at in-mold molding by placing a heat-resistant film on the surface of at least a part facing to a gate. CONSTITUTION:A compression mold 5 is brought into contact with a core mold 3 and a molten resin 6 consisting of polypropylene with a predetermined quantity is injected in a cavity from a gate set on the compression mold 5. In this case, as an opening of the gate 50 is faced to an aluminum foil 4, the molten resin 6 is at first brought into contact with the aluminum foil 4. Therefore, heat of the molten resin 6 is prevented from transmitting directly to a foamed layer 11 and the foamed layer at that part is prevented from receiving damage by heat. In addition, as the vol. of the molten resin is smaller than the vol. of the cavity at that time, a pressure applied on the skin material 1 is small and there exists neither damage nor displacement of the skin material 1. Then, a compression mold 5 is relatively forwarded to compress the molten resin 6 and to perform compression molding and a semidivided body 7 with an arc- shaped crosssection is obtd.

Description

[Detailed Description of the Invention] [Industrial Application Field] The present invention relates to an in-mold molding method in which a skin material is placed in a mold, resin is injected, and then compression molded. It is used when using a skin material with a foam layer made of plastic resin.

[Prior Art] Conventionally, a molded body has been formed by placing a skin material in a cavity and integrally covering the molded body with the skin material. In this case, when injection molding is used, the injection pressure is high and the position of the skin material may shift within the cavity.
Since the skin material may be damaged, compression molding is usually used.

However, in compression molding, there are difficulties in the method of supplying the molten resin, so in recent years, injection compression molding has been used. In this injection compression molding method, a gate is provided in the compression mold,
This is a method in which a predetermined amount of resin is injected into the cavity before compression, and then compressed and molded using a compression mold. According to this injection compression molding method, supply of molten resin is extremely easy and molding can be performed at low pressure, so it is suitable for an in-mold molding method in which a skin material is placed and molded.

[Problems to be Solved by the Invention] As the skin material, a soft skin material having a skin made of vinyl chloride or the like and a foam layer made of polyethylene or polypropylene on the back side of the skin is sometimes used. If such a skin material is used, the foam layer near the compression type game 1 will be eroded by the heat of the injected resin.
In the resulting product, there were cases where depressions were formed in the epidermis of the affected area.

The present invention was made in view of these circumstances, and
In an in-mold molding method, the purpose is to prevent the foam layer from being attacked by the heat of the injected resin.

[Means for Solving the Problems 1] The in-mold molding method of the present invention involves disposing a skin material having an integral foam layer on the surface side in a mold, and pouring a predetermined amount of molten resin through a gate formed in a compression mold. This is an in-mold molding method in which a contact compression mold injected into a mold is advanced and compression molded, and a heat-resistant film is held on at least the surface of the foam layer facing the gate, and the molten resin is transferred to the heat-resistant film. It is characterized by being ejected in the opposite direction.

As the skin material, materials similar to those conventionally used can be used, and in the case of the present invention, polyethylene film 4-
It is also possible to use a foam layer made of a thermoplastic resin with low heat resistance, such as foam or polypropylene foam. The type of molten resin is also not particularly limited, and any resin that has good affinity with the foam layer, preferably the same resin as the foam layer, can be used.

The greatest feature of the present invention is that a heat-resistant film is held on the surface of at least the portion of the foam layer facing the gel 1. The material for this heat-resistant film is not particularly limited as long as it can withstand the heat of the injected molten resin, and for example, metal foil such as aluminum foil or copper foil can be used. It is desirable that it be thin and flexible so as not to interfere with the flexibility of the foam layer.

The heat-resistant film may be integrally combined with the foam layer by sewing or the like, or it may be placed separately when the skin material is placed in the mold.

[Operations and Effects of the Invention] In the in-mold molding method of the present invention, a heat-resistant film is disposed on the surface of at least the portion of the foamed layer facing the gate. Therefore, the injected molten resin first comes into contact with the heat-resistant film, and the heat of the molten resin is prevented from being directly transmitted to the foam layer at that portion. Therefore, since there is a one-cussion before the heat is transferred to the foam layer, when the heat is transferred to the foam layer, the temperature has decreased, so that damage to the foam layer is less likely to occur. By moving the compression mold relatively forward, the molten resin is compressed and spread into the cavity, and is cooled to form a molded body integrally combined with the foam layer and the heat-resistant film.

Therefore, according to the in-mold molding method of the present invention, since the foam layer is prevented from being attacked by heat, an excellent molded article without surface defects can be stably formed.

``Example'' The present invention will be described in detail with reference to an example. In this example, the present invention is applied to the manufacture of an assist grip for an automobile.

As shown in FIG. 1, a vinyl chloride skin 10 and a skin 1
A skin material 1 consisting of a polypropylene foam layer 11 integrally bonded to the back side of the 0 is prepared, and the skin material 1 is formed into a predetermined arcuate cross-sectional shape by vacuum forming.

This shaped skin material 1 is placed in the upper mold 2 of an injection compression mold, and the middle mold 3 is closed to fix the skin material 1. Here, an aluminum foil (heat-resistant film) 4 is fixed to the center of the foam layer 11 of the skin material 1 by adhesive.

Here, the mold shown in FIG. 1 includes a lower mold 2, a middle mold 3,
The lower mold 2 and the middle mold 3 are each clamped, and further clamped to the compression mold 5. The compression mold 5 is provided with a gate 50, the nozzle 51 of the injection molding machine comes into contact with the back surface of the compression mold 5, and the molten resin 6 injected from the nozzle 51 passes through the butt 50 and is injected from the tip of the compression mold 5. It is.

Next, as shown in FIG. 1, the compression mold 5 is brought into contact with the medium mold 3, and molten resin 6 made of polypropylene is injected into the cavity from the gate 50 provided on the compression mold 5 for a preset period of time. . Here, the opening of the gate 50 is made of aluminum foil 4.
As shown in FIG. 1, the molten resin 6 first comes into contact with the aluminum foil 4. Therefore, the heat of the molten resin 6 is prevented from being directly transferred to the foam layer 11, and the foam layer 11 in that area is prevented from being immersed in heat. Further, since the volume of the molten resin is smaller than the volume of the cavity at that point, the pressure acting on the skin material 1 is small, and the skin material 1 is not damaged or displaced.

Next, the compression mold 5 moves relatively forward to compress the molten resin 6 to perform compression molding, and as shown in FIG. 2, a half body 7 having an arcuate cross section is obtained. This half body 7 consists of a polypropylene base material 70, an aluminum foil 4, a foam layer 11, and a skin 1.
0 are integrally joined.

As shown in FIG. 3, this half body 7 is combined with the other half body 8 molded separately, a core material 8 is placed inside, and each is fixed by welding, gluing, etc. to form an assist grip. be done.

Therefore, according to the molding method of this embodiment, the foam layer 11 is prevented from being attacked by heat due to the presence of the aluminum foil 4, so that an assist grip with an excellent surface appearance can be easily and stably formed. I can do something.

[Brief explanation of the drawing]

The drawings relate to a molding method according to an embodiment of the present invention, in which Fig. 1 is a sectional view showing the state in which molten resin is injected, Fig. 2 is a sectional view showing the state at the end of compression molding, and Fig. 3 is a sectional view showing the state after compression molding is completed. FIG. 3 is a sectional view of the assist grip. 1...Skin material 2...Bottom mold 3...
Medium size 4... Aluminum foil (heat resistant film) 5... Compression mold 6... Molten resin 10...
Epidermis 11...Foam layer 50...Gate patent applicant Toyoda Gosei Co., Ltd.

Claims (1)

[Claims] (1) A skin material with an integral foam layer on the surface side is placed in a mold, a predetermined amount of molten resin is injected into the mold from a gate formed in a compression mold, and then the compression mold is moved forward to perform compression molding. An in-mold molding method characterized in that a heat-resistant film is held on the surface of at least a portion of the foamed layer facing the gate, and the molten resin is injected toward the heat-resistant film. Mold forming method.