JPS59225936A - Preparation of laminated injection molded article - Google Patents

Abstract

PURPOSE:To obtain a laminated injection molded article having a uniform laminated structure even in the vicinity of a welded part, by providing an extended part capable of being filled with a skin layer and a core layer forming resins to the welded part of an objective molded article. CONSTITUTION:A skin layer forming resin is injected into a mold having an extended part provided to the welded part thereof in an amount insulfficient for filling the space of the mold and, before the inner surface of the skin layer forming resin is solidified, a core layer forming resin containing a blowing agent is succeedingly injected into the mold. After the resins are solidified, the laminated injection molded article molded in the extended part is cut off along the outer periphery of an objective molded article by a knife. The volume of the extended part is affected by the properties of the resin materials and the shape and size of the molded article but can be experimentally and easily determined by the volume adjustable extended part.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a core 7 for a long article such as a steering wheel for an automobile.
The present invention relates to a method for manufacturing a laminated injection molded product comprising a skin layer and a skin layer.

The present invention provides a laminated injection molded product that is very lightweight and has the same flexibility in all parts because the core layer is uniformly distributed even in the weld part.

Conventionally, in laminated injection molding of long objects such as automotive nozzles, the skin layer forming resin is pushed from two directions by the core layer forming resin in the welded part of the molded product, and there is no place for escape, so the skin layer forming resin is mostly used. It consisted of This has been a major problem in reducing the weight and achieving a uniform feel of laminated injection molded products. Particularly in the case of multi-point gates and a large number of welds, a lightweight laminated injection molded product cannot be obtained at all, which is a very serious drawback in terms of the marketability of the laminated injection molded product. In particular, in order to make a flexible and soft foam by injection molding a foamable resin in the core layer, it is necessary to make a shorter shot than when injection molding a non-foamable resin. It is difficult to form a uniform foam core layer even in the weld area because the foam expands sufficiently under the foaming pressure. In other words, in the weld area, there is less foam core layer and the pressure is not sufficient, so the foam cells are larger than in the gate area and cause local wobbling in the molded product, resulting in a uniform molded product. It had the disadvantage of not becoming

Although the basic manufacturing method for laminated injection molded products was invented more than 15 years ago, commercialization is still delayed, partly due to the unresolved problem of the weld area. This is because

The present invention compensates for these drawbacks and provides a laminated injection molded product that is much lighter and has the same flexibility in all parts.

In the method for manufacturing a laminated injection molded product, the present invention provides a skin and a core in the weld part of the target molded product when molding a long product with a large L/T such as an automobile steering wheel that is difficult to fill with a core layer. Providing an extension that can be filled with layer-forming resin,
After forming a laminated injection molded product of the skin and core layers on the target molded product part and the extension part, and solidifying the resin, the laminated injection molded product molded in the extension part is removed from the target molded product. This is a method for manufacturing an lfR layer injection molded product characterized by having a uniform laminated structure even near the weld portion.

The mold extension used in the present invention can be easily separated from the molded product even after the molded product and the extension are removed from the mold or during the molding process while they are in the mold. . For example, the resin is guided into the extension part through a hole of about 1216 (fin) size, and when the mold is opened, the movable plate moves and the resin is torn off, and after the molded product is removed from the mold, it is applied to the outer periphery of the molded product. Then, it can be cut out with a knife or the like. The filling amount of the molded part and extension part is
The amount is such that the molded part has a laminated structure with as many core layers as possible, and the extension part also has a laminated structure consisting of a skin layer and a core layer. The volume of the extension depends on the nature of the resin material used and the shape and size of the molded article produced. However, since the extension part is recycled or disposed of, it is desirable that the extension part be as small as possible while still providing a satisfactory molded product. This size can be easily determined experimentally by a possible extension of the volume. The shape of the extension is not particularly limited as long as it is sufficiently filled with the core layer. In addition, by providing an extension, a part of the outer circumferential surface of the molded product will be scratched to prevent cutting, so the core layer must be sufficiently filled in the extension at low pressure in the cross-sectional area of the connection between the molded product and the extension. It is desirable that the size be as small as possible within the range that allows a satisfactory molded product to be obtained. Furthermore, it is necessary to ensure that the gate and weld are located in inconspicuous locations from the time of designing the mold. Of course, it is also possible to use a non-foamed material for the core layer.

Furthermore, the method of the present invention can be used without any problems and is not limited to any resin as long as it is based not only on vinyl chloride resin but also on thermoplastic resin.

Next, typical examples of the present invention will be explained.

An automotive nozzle with an iron core was molded using an injection molding machine for laminated product molding with a mold clamping force of 200 tons, which has two cylinder units that meet at the nozzle. An insufficient amount of polyvinyl chloride skin layer-forming resin is injected into the mold to fill the mold space, and before the inner surface of the skin layer-forming resin solidifies, a blowing agent containing foaming agent is injected into the mold. Subsequently, the core layer forming resin of polyvinyl chloride is injected 7'i).

As a result, a handle was obtained in which the skin layer of the molded product containing the iron core was made of polyvinyl chloride and the core layer was made of foamed polyvinyl chloride. Diameter g from the back of the outer periphery of the weld part
8 (nr + n), length 10 (M) hole, length 30 (recess)
, Width 30 (Ki), Height 30 (Kai), Volume 270 (mJ)
The resin was guided to the extension of the mold, and was torn off as the movable plate moved when the mold was opened.After the handle was removed from the mold, it was processed with a knife along the outer periphery of the molded product.

Of course, after the molded article has been removed from the mold, it may be treated with a suitable cutting instrument such as a knife. The extension made of the polyvinyl chloride skin layer and the foamed polyvinyl chloride core layer was cut into pellets, mixed with the foamed polyvinyl chloride core layer forming resin, and recycled.

The materials used in this example had the following composition, and were mixed in a super mixer and then made into a cross-wire pellet in a Banbury mixer.

Skin layer forming resin polyvinyl chloride (P=1100) 100DOP

80 Epoxidized dog bean oil 3Ba
-Zn- based stabilizer 2 core layer forming resin polyvinyl chloride (P = 1400) 100DOP
5゜Epoxidized soybean oil 5Ba-Zn stabilizer
3ADCA (foaming agent)
3 The dimensions of the nozzle obtained in this example are as follows.

Diameter of handle: 380 (w) Diameter of outer grip portion: 28 (tone) Diameter of core material (iron): 14 (fin) Table 1 shows a comparison of molded products with and without extensions. .

Table-1 0・・・・・・・・・恢艮△・・・・・・・・・Slightly bad ×・・・・・・RL、As shown in this example, the manufacturing method according to the present invention is , which further improves the field and performance of laminated products.

Claims (1)

[Claims] A core layer containing a foaming agent is formed by injecting an insufficient amount of skin layer forming resin into the mold to fill the mold space, and before the inner surface of the skin layer forming resin hardens. In a method of manufacturing a laminated injection molded product in which resin is continuously injected, an extension part that can be filled with the skin and core layer forming resin is provided in the weld part of the target molded product, and the skin is injected into the target molded part and the extension part. , by forming a laminated injection molded product of the core layer and solidifying the resin, the laminated injection molded product molded in the extension part is removed from the desired molded product, thereby creating a uniform layer even near the weld area. A method for manufacturing a laminated injection molded product characterized by having a laminated structure.