JPH0847942A - Parts for mold insert - Google Patents

Abstract

PURPOSE:To bond a metal whose physical property is entirely different to a molding resin smoothly without generating crack and defective adhesion by a metal insert part for a resin molded piece wherein the surface of the part is covered with a layer of a crystal thermoplastic resin. CONSTITUTION:A cylindrical metal body is molded as an insert part. The cylindrical metal body 1 is made of brass, has an inner diameter of 4mm, an outer diameter of 8mm, and a length of 10mm. The whole outer periphery of the cylindrical metal body 1 is covered with a layer of a polypropylene (PP) 2 to a thickness of 0.8 mm or more by injection molding. As a thermoplastic resin, a polybutylene terephthalate (PBT) 2 is used. The outer periphery is covered with a layer of 1 mm, as well.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a mold insert part for encapsulating a metal member when inserting the metal member into a resin molded product.

There is an application for integrally molding various metal fittings with a resin molded product. The structure which is embedded or penetrated in a resin wall is often used for doors, housings, chassis and the like in many fields such as various electronic / electrical parts, OA equipments, daily necessities, automobiles and the like. In such various applications, there are many applications in which metal fittings suitable for mechanical or electrical applications are inserted and molded.

[0003]

2. Description of the Related Art The resin penetrating portion of such a metal insert has a drawback that a gap or a crack is generated due to shrinkage of the resin after molding. In particular, the amorphous resin has better dimensional accuracy than the crystalline resin and is suitable for large-sized parts, but it has been pointed out that when relatively large metal fittings are inserted, cracks frequently occur.

It is understood that the reason why such cracking occurs is that the expansion and contraction characteristics and the heat transfer coefficient of the metal and the resin are different.

In various applications as described above, it is required that the metal penetrating portion be kept tight and strong in order to keep airtightness between the inside and the outside or to keep mechanical stability.

Therefore, if the insert portion is cracked, these requirements cannot be satisfied, which is not desirable.

[0007]

SUMMARY OF THE INVENTION An object of the present invention is to provide a metal mold insert member for a resin molded product, which is a mold insert component which eliminates the drawbacks of the prior art.

[0008]

The problem to be solved by the present invention is a metal insert part for a resin molded product, the part for mold insert having a surface coated with a crystalline thermoplastic resin. To be done.

The crystalline resin used here can be selected from polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide, polyphenylene sulfide, etc., and can be selected according to the resin forming the mold, for example. .

[0010]

According to the mold insert component of the present invention, a layer of crystalline resin is provided in advance at a portion which penetrates or is embedded in the wall or the like of the resin molded product. As a result of providing such a layer, a metal having completely different physical properties,
The resin for molding is reasonably adhered, and cracks and poor adhesion do not occur.

In this case, the type of the crystalline resin, the thickness of the layer to be coated, etc. should be changed appropriately depending on the type of the resin forming the molded product, the presence or absence of the additive and the type, the size of the molded product, the use, etc. You can

[0012]

The present invention will be disclosed in detail below based on examples. FIG. 1 shows an example in which a tubular metal body is formed as an insert part. The tubular metal body 1 is a tubular body made of brass, having an inner diameter of 4 mm, an outer diameter of 8 mm, and a length of 10 mm.

In the first embodiment, polypropylene (PP) is layered by injection molding on the entire circumference of the cylindrical metal body shown in FIG. 1 so as to have a thickness of 0.8 mm ( (Fig. 2).

In the second embodiment, polybutylene terephthalate (PBT) was used as the thermoplastic resin, and a 1 mm layer was similarly applied to the outer circumference.

The third embodiment is the same as the first and second embodiments except that polyamide (PA) is used as the thermoplastic resin.

Using these samples, a boss-type molded product 2 as shown in FIG. 3 was prepared by using an amorphous resin, polycarbonate Lexan (trademark: manufactured by Nippon GE Plastics Co., Ltd.). As Comparative Example 1, a cylindrical metal body not coated with a resin was used, and as Comparative Example 2, the cylindrical metal body was coated with polypropylene to a thickness of 0.5 mm. A boss type molded body similar to the example was prepared and the following tests were conducted.

In the test, heat shocks of -30 ° C. to 80 ° C. were applied to the boss-type molded bodies prepared in Examples and Comparative Examples for 10 cycles, and then the presence or absence of cracks around the metal insert was evaluated. The evaluation results are as shown in Table 1.

[0018]

[Table 1]

[0019]

EFFECTS OF THE INVENTION The molded product insert-molded using the mold insert part according to the present invention not only has excellent adhesion between the metal insert and the surrounding resin,
No crack occurs even by heat shock due to a temperature difference of 100 degrees or more. Therefore, it is possible to easily obtain a molded product in which a large-sized metal body is inserted by an amorphous resin which is excellent in dimensional accuracy and is easy to obtain a large-shaped product. Molded products suitable for large-scale parts such as copiers and other office automation equipment, computer peripheral equipment housings, doors, etc. can be obtained.

Therefore, in the prior art, the restriction on the design and manufacturing for the large-sized molded product which requires the metal insert can be eliminated, and the number of parts and the manufacturing cost can be reduced.

[Brief description of drawings]

FIG. 1 is an explanatory diagram showing a basic configuration of a mold insert component according to the present invention.

FIG. 2 is a perspective view showing a state in which a crystalline resin is layered on the entire outer periphery of the mold insert component shown in FIG.

FIG. 3 is a perspective view showing a configuration example of a boss type molded product into which the mold insert component shown in FIG. 1 is inserted.

[Explanation of symbols]

 1 Metal Cylindrical Body 2 Crystalline Resin Cover Layer 3 Metal Body Inserted Boss Molded Body

Claims (3)

[Claims] 1. A mold insert component for a resin molded product, wherein a surface of the metal insert component is coated with a crystalline thermoplastic resin. 2. The mold insert component according to claim 1, wherein the thermoplastic resin layer is a layer having a thickness of 0.8 mm or more. 3. The thermoplastic resin forming the layer to be coated is one selected from polyethylene, polypropylene, polyethylene terephthalate, polybutylene terephthalate, polyamide and polyphenylene sulfide.
The mold insert component according to claim 1.