JPS642487B2 - - Google Patents

Description

[Detailed description of the invention]

INDUSTRIAL APPLICATION FIELD The present invention relates to a method for manufacturing engineering plastic molded products such as polyphenylene oxide, polycarbonate, etc., and in particular to a method for manufacturing engineering plastic molded products that can be molded without causing cracks in the molded product at low mold temperatures. Regarding the manufacturing method. Prior Art and its Problems Recently, engineering plastic molded products such as polyphenylene oxide and polycarbonate have been increasingly used for industrial parts such as structural parts and mechanical parts. These engineering plastic molded products are light and
In addition to having the same advantages as general plastic materials, such as high corrosion resistance, it also has excellent mechanical properties such as impact resistance and thermal properties, making it suitable for use as industrial parts. However, in order to fully demonstrate these characteristics,
It is necessary to eliminate inconveniences such as generating large residual stress in the molded product during molding, and to mold a good molded product without defects. For this purpose, conventionally, the shape of the molded product, the gate position, etc. have been devised so that the molten resin supplied into the mold can flow smoothly, and when the mold temperature is low, the molten resin supplied into the mold has been devised. is rapidly cooled and solidified, and large residual stress is generated inside the molded product, which may cause cracks in the molded product.To prevent thermal stress from occurring due to rapid cooling of the molten resin, the mold is usually heated to 80°C. Keep the mold temperature above ℃ and keep the mold temperature at 80℃.
Molding was carried out while keeping the temperature above ℃.
However, performing molding while keeping the mold at a fairly high temperature in this manner causes problems in molding workability, inefficiently molding, and increases molding cost. SUMMARY OF THE INVENTION The present inventors have improved the above-mentioned circumstances, and have made it possible to produce engineering plastic molded products such as polyphenylene oxide without causing defects such as cracks without taking any special heat-insulating measures for the mold. As a result of intensive research on the method, we used a mold with a composite plating coating in which a fluorine-based polymer material was eutectoidally dispersed on the cavity surface, and supplied molten resin to the cavity of this mold. We have discovered that when molding is carried out, even if the mold temperature is low, it is possible to reliably produce engineering plastic molded products with low internal residual stress and the occurrence of cracks, etc. being prevented as much as possible, The present invention has been accomplished. That is, in the present invention, a molten engineering plastic molding material is supplied to the cavity of a mold in which a composite plating film in which a fluorine-based polymer substance is dispersed and eutectoid is formed on the cavity surface, and the mold temperature is 10 to 60°C.
The present invention provides a method for manufacturing an engineering plastic molded article, which comprises molding an engineering plastic molded article. According to the present invention, by forming a composite plating film in which a fluorine-based polymer substance is eutectoidally dispersed on the cavity surface, it has an excellent heat insulation effect or heat retention effect, and molding can be performed without special heat insulation of the mold. By slowing down the cooling rate of the product, the generation of thermal stress can be prevented as much as possible, and residual stress in the molded product can be reduced.
Therefore, it can be molded at a low mold temperature,
For example, there is no need to take special measures such as installing a heat insulating device in the mold, and the mold at room temperature can be used as is for molding. In addition, the mold described above has very good mold release properties, which reduces mold release resistance during mold release (demolding), resulting in extremely low distortion during mold release, and in this respect also reduces residual stress. Therefore, by employing the method of the present invention, it is possible to reliably and efficiently mold good engineering plastic molded products without cracks or the like. Further, according to the present invention, it is possible to omit or simplify the need to keep the mold warm, resulting in good workability. The present invention will be explained in more detail below. Structure of the Invention The present invention relates to a method for manufacturing an engineering plastic molded article, but the engineering plastics to which the method of the present invention can be applied include, but are not limited to, polyphenylene oxide, polycarbonate, polyacetal, Examples include polyamide, polyethylene terephthalate, polybutylene terephthalate, polyphenylene sulfide, polysulfone, polyether sulfone, polyether ether ketone, polyarylate, polyetherimide, polyoxybenzylene, and the like. Among these, polyphenylene oxide, polycarbonate, polysulfon, polyether sulfon,
Polyarylate, polyetherimide, etc. are preferred, and the method of the present invention is suitably employed for producing these engineering plastic molded products. The manufacturing method of the present invention includes, as a mold to which the molten resin of the engineering plastic is supplied,
A composite plating film in which a fluorine-based polymer substance is eutectoidally dispersed is formed on the cavity surface. Here, there is no particular restriction on the material of the mold or the material of the cavity surface, and for example, ordinary materials for manufacturing molds such as steel and aluminum may be used. Further, the composite plating film formed on the cavity surface of this mold is one in which a fluorine-based polymer substance is uniformly eutectoid-dispersed in the plating film matrix. In this case, the fluorine-based polymer substances include polytetrafluoroethylene, polychlorotrifluoroethylene, polyvinylidene fluoride, tetrafluoroethylene-hexafluoropropylene copolymer, tetrafluoroethylene-ethylene copolymer, and chlorotrifluoroethylene. Fluoroethylene-alkylene copolymer, vinylidene fluoride-hexafluoropropylene copolymer, vinylidene fluoride-chlorotrifluoroethylene copolymer, vinylidene fluoride-pentafluoropropylene copolymer, and other fluororesin powders , short fibers, and fluorinated graphite particles. In addition, when using powder as the above-mentioned polymer substance, the average particle size is 0.01 to 200 μm, especially
The length is preferably 0.1 to 20 μm, and when a fibrous material is used, the length is 0.01 to 2000 μm,
In particular, it is preferably 0.1 to 60 μm. Examples of the plating film that serves as the parent phase in which the above-mentioned fluorine-based polymer substances are eutectoidally dispersed include plating films made of nickel, nickel alloys such as nickel-phosphorus alloys, iron, iron alloys, copper, and copper alloys. However, nickel and nickel alloy plating films are particularly suitable. As a method for forming such a composite plating film in which a fluorine-based polymer substance is eutectoidally dispersed in the plating film, an electroplating method or an electroless plating method may be used. A known composite plating method involves preparing a composite plating solution in which a fluorine-based polymer substance is suspended in an appropriate plating solution capable of forming a desired matrix, and performing plating using this plating solution. Can be adopted. In this case, the amount of fluorine-based polymer substance in the composite plating film to be formed is 2 to 65% by volume, especially 15 to 40% by volume, and the thickness of the plating film is 0.1 to 1000 μm, especially 5 to 30 μm. This is preferable in order to more reliably achieve the object of the present invention. The present invention uses the above-mentioned composite plating film forming mold, and supplies the above-mentioned molten resin of the engineering plastic into the mold cavity by an injection method or the like, and the mold temperature is 10-60°C, preferably 30-60°C.
Molding is carried out at 50°C. In this case, other molding conditions may be known molding conditions depending on the molding method such as injection molding, the type of plastic to be molded, the use of the molded product, etc. Furthermore, the molding material supplied to the cavity may also have appropriate components such as fillers added and kneaded in addition to the resin component. Effects of the Invention As mentioned above, the molded product obtained by employing the manufacturing method of the present invention has low residual stress and
Since it has very few defects such as cracks, the original characteristics of engineering plastics can be effectively exhibited, and therefore it is suitable for use in various industrial parts. EXAMPLES Hereinafter, the present invention will be specifically explained by showing examples and comparative examples, but the present invention is not limited to the following examples. [Example 1, Comparative Example 1] A composite plating solution in which polytetrafluoroethylene particles were uniformly dispersed in a nickel plating film was prepared by using a composite plating solution with the following composition on the steel insert cavity surface of a rib plate mold. A plating film was formed. Composite plating solution composition Nickel sulfamate 500ml / Nickel chloride 30g / Boric acid 35 Polytetrafluoroethylene 70 Dispersion aid 2 PH 4.0 Composite plating conditions Cathode current density 2A/dm ² Bath temperature 45℃ Composite plating film Film thickness: 15 μm Composition: Contains 35 vol% polytetrafluoroethylene Next, using the above mold, polyphenylene oxide was molded at a mold temperature of 40°C using a NETSTAL75T manufactured by Sumitomo Heavy Industries, Ltd. as a molding machine. , molded product (rib plate shown in Figures 1 and 2)
After heat-treating at 90°C for 24 hours, the degree of crack generation was evaluated. The results are shown in Table 1. Note that a in the figure is a gate. Table 2 also shows the results of measuring the temperature of the molded product. Here, to evaluate cracks, observe the molded product with a 10x magnifying glass to confirm the presence or absence of cracks, and evaluate the cracks as 3 points for large cracks, 2 points for medium cracks, and 1 point for small cracks. Scored.
The temperature of the molded product was measured at the point b in FIG. 1 for the 15th shot of the molded product. For comparison, polyphenylene oxide was molded in the same manner using a steel insert cavity surface coated with ceramic and an aluminum insert, respectively, and the degree of cracking in the molded product was examined. The results are also listed in Table 1.

【table】

[Example 2, Comparative Example 2]

In the same manner as in Example 1, nickel plating films with various polytetrafluoroethylene eutectoid amounts and film thicknesses shown in Table 3 were applied to the steel (SCM-4) insert cavity surface of the rib plate mold as the matrix. A composite plating film was formed.

[Table] Next, using the above mold and the same molding machine as in Example 1, polyphenylene oxide (PPO) and polycarbonate (PC) were molded at a mold temperature of 30°C.
The molding process was carried out. The obtained PPO molded product was heated to 90℃.
After heat treatment for 24 hours, the degree of crack generation was evaluated in the same manner as in Example 1, and the results shown in Table 4 were obtained. In addition, the mold temperature was measured during molding of the PPO molded product and the PC molded product, and the degree of temperature rise (temperature difference Δt) after 30 shots was examined to evaluate the degree of heat insulation of the cavity. The results for molding PPO molded products are shown in Table 5, and the results for molding PC molded products are shown in Table 6.

【table】

【table】

[Table] From the results in Table 4, forming a polytetrafluoroethylene eutectoid composite plating film on the cavity surface can greatly improve crack resistance, and the molded product will not crack even if the mold temperature is lowered. It was found that molding could be carried out satisfactorily without causing any problems. The results in Table 4 are the results of examining the degree of crack occurrence after heat treatment of molded products, but the results are for molded products that were molded using a composite plating film forming mold without subsequent heat treatment. No cracks were recognized. As mentioned above, there are various possible reasons why the formation of a composite plating film can significantly improve crack resistance.
As shown in the table, the heat insulation effect of the composite plating film forming mold is high, and the rapid cooling process of the injected resin when it comes into contact with the mold cavity surface is alleviated.
This was thought to be due to the relaxation of internal residual stress. In addition, according to polarized photographs of PC molded products, it was observed that the residual stress near the protruding pins was considerably reduced in the case of molded products using composite plating film forming molds, and therefore the composite plating film It has been recognized that mold release resistance can be reduced by using a forming mold, and the reduction in strain during mold release due to such a reduction in mold release resistance is also thought to be one of the causes of improved crack resistance. Ta.

[Brief explanation of drawings]

FIGS. 1 and 2 each show a molded product used to examine the degree of crack occurrence, with FIG. 1 being a perspective view of the back side, and FIG. 2 being a perspective view of the front side.

Claims (1)

[Claims] 1. A molten engineering plastic molding material is supplied to the cavity of a mold in which a composite plating film in which a fluorine-based polymer substance is dispersed and co-deposited is formed on the cavity surface, and an engineering plastic molded product is formed at a mold temperature of 10 to 60°C. A method for manufacturing an engineering plastic molded product, characterized by molding.