JPS6049578B2 - How to insert metal etc. into synthetic resin - Google Patents

Description

[Detailed Description of the Invention] The present invention relates to a method for inserting inorganic materials such as metals and ceramics, plastics, etc. (hereinafter sometimes abbreviated as metals, etc.) into synthetic resins. This is to prevent cracks from forming.

BACKGROUND OF THE INVENTION There have been many articles in which metal or the like has been inserted into synthetic resin, such as tableware such as knives, forks, spoons, and pot lid knobs, and parts of various devices with inserts such as bolts and ceramics.

These are useful for achieving purposes such as insulation, heat insulation, aesthetics, and texture. However, on the other hand, if the insert fitting comes off or rotates from the synthetic resin part, not only will the above purpose not be achieved, but the original function of the insert fitting will often be lost. To prevent this, the metal inserts are made into a spiral shape or have irregularities. However, no good measures have been taken to prevent cracks, which is another drawback of insert products. Cracks cause stress concentration. However, this is particularly likely to occur on the bonding surfaces between metals with different coefficients of expansion and synthetic resins, and not only does this damage the aesthetics, but if left untreated, the synthetic resin parts may become chipped or the inserts may come off. This can lead to negative effects such as As a result of intensive study on this point, the inventors of the present invention have discovered a preventive measure that is relatively simple and has the greatest effect, and has thus arrived at the invention.

That is, the present invention is a method of inserting metal or the like into a synthetic resin, in which a fibrous material is attached to an insert fitting to a certain width and height, and then insert molding is performed by a conventional method. The difference between the method of the present invention and the conventional method is whether or not a fibrous material is attached to the metal insert, and stress resulting from the adhesive surface between metal etc. and synthetic resin and the difference in expansion coefficient between metal etc. and synthetic resin. Surprisingly, cracks that occur in the conventional method do not occur in the method of the present invention, even though the underlying factors that cause cracks to occur, such as concentration, occur in the same way. The reason for this is not clear, but perhaps the fibrous material has a buffering effect.
Alternatively, it is thought that the expansion coefficients of the metal etc. and the synthetic resin become close to each other due to the mixture of these substances. The present invention is applicable to synthetic resins in general, and there is no distinction between thermoplastic resins and thermosetting resins. Since thermosetting resins are prone to cracking, the effects of the present invention are particularly noticeable on melamine resins and phenolic resins. Conventional methods such as compression molding, injection molding, and transfer molding are commonly used for insert molding. The fibrous material of the present invention may be either inorganic fibers such as asbestos, glass wool, or long cellulose fibers, or organic fibers. In order to attach these to the insert metal fitting at a certain width and height, it is possible to roll them around the insert metal fitting to a width as shown in Fig. 2b and a height as shown in h. A circular backing with a hollow center cut out of a non-woven fabric or the like having a certain thickness with intertwined fibers may be inserted into the insert fitting as shown in Fig. 3, or the insert fitting may be further wrapped as shown in Fig. 4. Methods similar to these can be used if they can achieve the same effect. In addition, when attaching the fibrous material to the insert metal fitting at a certain width and height, the fibrous material may be used as it is, or it may be impregnated with or adhered to a synthetic resin of the same quality as the synthetic resin to be molded, so that the fibrous material will not mix with the synthetic resin during molding. You can make it easier to get used to.

In the present invention, materials to be inserted into the synthetic resin include not only metals but also inorganic materials such as ceramics and ceramics, and plastics different from the synthetic resin to be inserted.

The surface of these metals and the like to be bonded to the synthetic resin may be flat as shown in 2 in FIG. 2, or it may be a rough surface, or it may be a convex surface. In addition, only insert fittings with no 2 (
For example, it can be fully applied to the case of embedding nuts, etc.). The insert method of the present invention completely prevents the occurrence of cracks in the synthetic resin part, has good adhesion, and can withstand long-term use without losing its aesthetic appearance. The present invention is widely applicable to various devices such as handles of tableware such as spoons and forks, knobs, handles of kettles, etc., as well as parts of electrical devices. The present invention will be described in detail below with reference to Examples, but the present invention is not limited thereto.

Example 1, Comparative Example 1 A circular backing-like object with a thickness of 6 TmIn, punched from an asbestos board as shown in Fig. 3, was fitted into a conventional synthetic resin knife insert fitting with a flat adhesive surface, and a melamine phenol resin ( 170℃, 20
Compression molding was performed using 0 kgIcT1 to obtain an insert knife.

On the other hand, an insert knife was made by compression molding under the same conditions as above without using a circular backing-shaped asbestos plate, and the product of the present invention and the occurrence of cracks were examined. The results were as follows. The knife was left in an atmosphere maintained at 100'C using a hot air dryer, and after drying, it was taken out and immediately placed in water at 10°C to rapidly cool it and left for 5 minutes. This cycle was taken as one cycle, and after 20 cycles, the crack occurrence rate among 50 knives made by the conventional method was 20%, but the crack occurrence rate was 0 for the knives made by the method of the present invention. Example 2, Comparative Example 2 A knife was produced in the same manner as in Example 1, except that melamine resin (Nicalet MCl, manufactured by Nippon Carbide Co., Ltd.) was used instead of the melamine-phenol resin in Example 1.

When this was compared with knives made by the conventional method in the crack generation test described in Example 1, the crack generation rate was 0 for 50 knives made by the method of the present invention, but the crack generation rate was 5 for the knives made by the conventional method.
It was 0%.

[Brief explanation of the drawing]

FIG. 1 is a front view of an insert knife, FIG. 2 is a sectional view of an embodiment of the present invention, and FIG. 3 is a perspective view of a fibrous material of the present invention. FIG. 4 shows a cross-sectional view of the metal insert wrapped in a fibrous material. DESCRIPTION OF SYMBOLS 1... Knife blade, 2... Metal body to be adhered to synthetic resin, 3... Synthetic resin handle, 4... Fibrous material, 5... Insert metal fitting.

Claims (1)

[Claims] 1 In the method of inserting metal etc. into synthetic resin,
A method of inserting metal, etc. into synthetic resin to prevent the occurrence of cracks, which is characterized by bonding a fibrous material to a certain width and height on an insert fitting and then insert molding using a conventional method.