JPH0363932B2 - - Google Patents

Description

[Detailed description of the invention]

[Industrial Field of Application] The present invention relates to a method for injection molding two types of resin compositions having different flows and providing a good appearance on the surface of a molded product. [Prior Art] Conventionally, the molded appearance of resin compositions containing glass fiber and other inorganic fillers has been severely roughened.
For this reason, it is well known that resin compositions with reduced glass fibers and inorganic fillers are used, as it is well known that the physical properties of the material are reduced, and if poor appearance is unavoidable, surface painting or two-color molding is recommended. Methods include using a multi-color molding machine, such as a typical molding machine, and a Sanderschich molding machine, which performs integral molding at the same time with a slight time difference from the same nozzle, and using a resin that has a good appearance for covering the surface. [Object of the Invention] The present invention aims to solve these resin compositions that are prone to poor appearance without degrading the properties of the material and without relying on dedicated machines such as conventional two-color molding machines. The present invention was achieved as a result of intensive efforts to improve the appearance of molded products using a general molding machine. [Structure of the Invention] The present invention provides a thermoplastic resin composition with a flow rate of 10% compared to the thermoplastic resin composition measured under the same conditions using a Koka type flow tester.
This is an injection molding method characterized by mixing a resin composition that is twice as large and having a good appearance on the surface of a molded article before injection molding, and then molding. Resin compositions that can be used in the present invention and have a good appearance on the surface of molded products include polyethylene, polypropylene, ABS, nylon, AS, and PES.
It is an injectable molding material with good appearance based on resin such as PPS-based, PPS-based, polyacetal-based, etc., and if the flow rate is 10 times or more when measured under the same conditions with a Koka type flow tester, it can be any material. It is possible to select a material that not only has a good appearance but also has the desired surface properties. In addition, even for resin compositions that tend to have poor molded appearance, materials with required properties can be freely selected depending on the purpose. Further, any general type of injection molding machine may be used. [Effects of the Invention] According to the method of the present invention, a resin with a flow rate of 10 times or more when measured under the same conditions with a Koka type flow tester as compared to any resin composition and with a good appearance on the surface of a molded product can be obtained. The composition is mixed and molded in an arbitrary ratio before injection molding, and the surface of the finished molded product has a good appearance.The following effects can be mentioned. (1) Increased costs due to secondary processing and the use of special machines such as painting and multi-color molding machines such as two-color molding machines and special machines such as Sandersch molding machines can be avoided. (2) In addition, in the case of multi-color molding machines such as two-color molding machines and Sanderschich molding machines, different materials tend to cause differences in molding shrinkage rates and poor adhesion between different materials, but the method of the present invention is applied. In a molded product made by injection molding of an arbitrary resin composition within the molded product and a resin composition with a good appearance on the surface of the molded product, the interface between the two materials changes continuously, so the average molding shrinkage rate Deformation caused by oxidation and sufficient adhesion strength can be obtained. (3) It is possible to arbitrarily select a molding material that has surface functions and a good appearance, and it is also possible to design a material that has both internal and surface properties. Example A The following two materials were mixed before injection molding as shown in Table 1, and a test piece was prepared using a Nippon Steel N-200 injection molding machine. The glossiness and surface roughness of the molded product surface were measured. Examined. According to this, it can be seen that the surface of the molded product obtained by mixing and molding at an arbitrary ratio is covered with a resin composition that has a good appearance and flows well. All formulations hereinafter are in parts by weight.

[Table] Example B When the following five materials were mixed as shown in Table 2 and evaluated in exactly the same manner as in Example 1, one material with a good appearance and the other material had a high fluidity. It can be seen that the tester requires a difference of more than 10 times.

【table】

[Table] Example C When the following four materials were mixed as shown in Table 3 and evaluated in exactly the same manner as in Example 1, it was found that the material strength could be freely designed as the material inside the molded product.

【table】

Claims (1)

[Claims] 1. Mixing a thermoplastic resin composition with a resin composition that has a flow rate of 10 times or more when measured under the same conditions using a Koka type flow tester and has a good appearance on the surface of the molded product before injection molding, An injection molding method characterized in that the method is then molded.