JPS6018334A - Surface curing method of resin molded article - Google Patents

Abstract

PURPOSE:To improve resistance to flaw and a quality level, by applying specific heat treatment to a resin molded material made from polypropylene or propylene-ethylene copolymer and a nucleating agent. CONSTITUTION:A resin molded article obtained by making use of a resin composite made from a polypropylene or propylene-ethylene copolymer and a nucleating agent is inserted into a furnace whose temperature is higher by 5-10 deg.C than that of crystallization of a material, which has been evaluated beforehand, and left for a predetermined period of time as it is. Then a temperature in the furnace is lowered at a predetermined rate, and surface hardness is raised by making crystallinity of a skin layer of the surface of the molded article improve more than the other part. As heat treatment is applied to polymer containing the uncleating agent like this, a crystal of the polymer of that part is turned into fine, dense and uniform structure and a non-crystalline part becomes smaller, it seems that hardness of the part is improved.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention is directed to surface hardening of resin molded products in which the degree of crystallinity of the surface layer of resin molded products is improved by heat treatment, which improves the scratch resistance and quality of the resin molded products. It is about the method.

Structures of conventional examples and their problems In general, resin materials cannot be said to have superior scratch resistance compared to other materials, and olefin-based molding materials in particular have a lower scratch resistance than other Tsukuda resin materials. It is something.

However, as petroleum prices have soared, many inexpensive olefin-based materials have come into use, but they currently have poor scratch resistance and are not widely used for exterior applications. Therefore, in order to make these scratches difficult to see, we have taken measures such as providing a guard and applying matte skin texture from the product design perspective.In addition, from the material perspective, we have considered various methods such as fillers, polymers, etc. However, there is currently no method that is most suitable for exterior applications. As a result, styrene-based materials, which are more expensive than olefin-based materials, are generally used for exterior materials. As described above, the reason why olefin-based materials are not widely put into practical use for exterior packaging is that they have serious problems with scratch resistance.

OBJECTS OF THE INVENTION The present invention obviates these drawbacks of the prior art.
The method is to increase the degree of crystallinity of the surface layer of an inexpensive crystalline material such as an olefin by heat-treating the molded product using a molding material containing a predetermined amount of a specific crystallization control material. The present invention provides a method for improving scratch resistance.

Components of the Invention The method for surface curing resin molded articles of the present invention uses an apparatus having a furnace body capable of lowering the temperature at a predetermined rate, and cures molded articles made of an olefin material containing a predetermined amount of a predetermined crystallization control material. is inserted into a furnace that is 5 to 1 o'C higher than the pre-evaluated crystallization temperature of the material, and left for a certain period of time.Then, the temperature inside this furnace is lowered at a certain rate, and the surface of the molded product is The crystallinity of the skin layer is increased compared to other parts, thereby increasing the surface hardness.

Description of examples Examples of the present invention will be specifically described below.

Example 1 0.2 wt% of aluminum benzoate and 0.1 wt% of dibenzylidene sorbitol were added to homopolypropylene with M, I (melt flow index) ~16, mixed and stirred in a high-speed mixer, and then extruded in a φ30 different direction vent type. After pelletizing in a machine and drying at 80"C, put the pellets into a molding machine, resin temperature 1800-230°C 1 mold temperature 30
A product of φ50×10t was molded at ~40'C to obtain a molded product. The crystallization temperature of this molded article was determined to be 135°C by thermal analysis. Therefore, the temperature of the furnace was set to about 140
The temperature was set at ~146°C, the molded article was inserted into this furnace, and after being left for about 30 minutes, the temperature was lowered to 40°C at a rate of 2°C/10, and the surface layer was heat-treated to form a hardened layer. The crystallinity of the surface layer of the lump was measured using a water-ethanol density gradient tube method, and the crystallinity was then converted to 6
It was 76-85 compared to 5-70. When the sample thus obtained was measured using a pencil hardness test method, the results were shown in Table 1.

Example-2 The same homobolyphic virens used in Example-1 (
(does not contain nucleating agent) resin temperature 1800-230℃
A product of φ5Q×10t was molded at a mold temperature of 30 to 40°C to obtain a molded product. This molded stain was heat treated in the same manner as in Example-1 to obtain a sample. The crystallinity of this sample was 60 to 66, and the hardness measurement results are shown in Table 1.

Example-3 The molded product obtained in Example-1 was placed in a furnace at about 140-145°C, left for about 30 minutes, then heated at 120-130°C for 30 minutes, then at 110-120"C for 30 minutes. , then 90℃~
A hardened layer was formed on the surface of the molded product by standing at 100°C for 30 minutes, then at 70-8Q°C for 30 minutes, and then at 50-60°C for 30 minutes. When the sample thus obtained was measured using a pencil hardness test method, the results were shown in Table 1.

Example-4 The molded product obtained in Example-1 was inserted into a furnace at about 140 to 146°C, and after being left for about 30 minutes, the temperature at 100°Ct was 0.5°C.
The temperature was lowered at a rate of 6°C/min until it reached 60°C, and a hardened layer was formed on the surface of the molded island. The samples obtained in this way were measured using the pencil hardness test method and Table 1
The results are shown in.

Example-9 Using M, l-24 ABS resin, resin temperature 230'C~
A product of φ50×10t was molded at 240° C. and a mold temperature of 40 to 60° C. to obtain a molded product. Table 1 shows the results of hardness measurement of this sample.

Examples 6 to 8 Using an ethylene-propylene block copolymer of M and I=20, a surface hardening treatment was performed in the same manner as in Examples 1, 2, 3, and 4 to form a hardened layer on the surface. When the sample thus obtained was measured using a pencil hardness test method, the results were shown in Table 1.

Reference Example-1, 2 Homopolypropylene with M, I=-1s and M, I=20
(Table 1 shows the hardness and crystallinity measurement results of the D-r-fV no-propylene broth copolymer.

Below is the margin table -1? (As explained above, in crystalline polymers, especially polypropylene, by adding a substance that has a nucleating effect to the polymer, the degree of crystallinity can be reduced to about 8.
%improves. Furthermore, by heat treatment at a temperature higher than the crystallization temperature of this polymer, the crystallinity of the surface area is further improved by about 20%, and the scratch resistance of this polypropylene is AB
It has become clear that S is the same as Ding.

By heat-treating a polymer containing a nucleating agent in this way, the polymer crystals in that area become fine, minutely dense, and homogeneous, and the amorphous area becomes smaller, improving the hardness of that area. It seems to be the case. In this text, a homopolymer grade polypropylene is used as the polypropylene, but the same effect can be obtained with a copolymer braid.

Name of agent: Patent attorney Toshio Nakao and 1 other person-1
75')-

Claims (1)

[Claims] After heating a resin molded article using a resin composition comprising either polypropylene or propylene-ethylene copolymer and a nucleating agent at a temperature equal to or higher than the crystallization temperature of the resin composition, it is heated at a predetermined rate. A surface hardening method for resin molded products in which the temperature is lowered to increase the degree of crystallinity of the surface layer of the molded product.