JPS6257501B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention is a filler-containing material with a smooth plating surface.
Regarding ABS resin injection molded products, this plated product is characterized by its excellent appearance while having practical performance such as dimensional stability, rigidity, and heat resistance. Plating is commonly performed on ABS resin molded products, and is often used for home appliance parts (for example, knobs and handles) and automobile parts. ABS resin is a thermoplastic resin that has relatively good moldability, dimensional accuracy, and dimensional stability, but it has even higher dimensional accuracy, dimensional stability, rigidity, and heat resistance for plated parts of injection molded products. is requested. On the other hand, it is already known that adding glass fiber, metal powder, etc. to ABS resin as a filler improves dimensional accuracy, rigidity, and heat resistance. However, silver streaks occur on the surface of injection molded products made of ABS resin with added fillers, and the filler comes out on the surface of the molded product, so even if this is plated, only a plated product with a rough surface can be obtained. However, despite the availability of significant materials, the plated product was never put into practical use. In the past, attempts have been made to perform injection molding by heating the mold temperature to about 70°C. This method can considerably improve the surface roughness of filled ABS resin, but when it is etched for plating, the ABS resin near the surface may be damaged and the fibrous filler may come out, or it may be pressed and bent. The fibrous filler, which had been trapped inside the molded product due to the resin being damaged, recovers from its deformation and protrudes onto the surface. As a result, the plated surface of the molded product was only rough and rough, which was not much different from the case described above. The present invention aims to solve the above-mentioned problems and provide a filled ABS resin injection molded product having an excellent plated surface. In other words, the present invention has a smooth skin layer made of ABS resin containing a filler as a constituent material, which is formed by a mold in which only the surface is heated, and is made of only ABS resin without the filler, and on top of this skin layer. This is an injection molded filled ABS resin plated product, which is characterized by having a plated surface. According to the present invention, surface smoothness and mold surface transferability are greatly improved, resulting in dimensional accuracy, dimensional stability,
A plated product with a mirror surface with improved heat resistance was obtained. The content of the filler in the skin layer of the resin molded product of the present invention is lower than that of conventional products, the flowability during molding is improved, and the bending of the fibrous filler is small, making it easier to etch. Even when this is applied, the smoothness of the molded product surface is not impaired. The present invention will now be described in further detail with reference to the accompanying drawings. First, the injection molding process of the plated product of the present invention will be explained. An injection molding apparatus is shown in FIGS. 1 and 2. This example shows an inductor insertion method, and includes an injection molding machine and a high-frequency It consists of a high frequency induction heater consisting of an oscillating device 1 and an inductor 2 connected to the oscillating device 1 and placed near the mold surface. ABS resin for injection molding is, for example, acrylonitrile-butadiene-styrene copolymer,
Acrylonitrile-butadiene-styrene-α-
Methyl styrene, acrylonitrile-methyl methacrylate-butadiene-styrene. Also, the filler mixed in this is 5 to 20 μm in diameter.
5-40% by weight of glass fiber, preferably 10-30%
Weight%. Furthermore, as another filler,
CaCo ₃ , inorganic substances such as glass beads, and Fe,
Examples include metals and alloys such as FeO ₃ , Al, and ZnO, and their oxides. The average particle size of such an inorganic material is 1 to 100 μm, and the content of the inorganic filler is 20 to 80% by weight. When such a material is injection molded, as shown in the enlarged cross section of Fig. 2, the fixed side mold 4 is
A high-frequency induction heating inductor 2 is installed between the moving mold 5 and the movable mold 5. When the inductor 2 is inserted between the movable mold 5 and the stationary mold 4 and a high frequency is oscillated in the sandwiched state, only the mold surface (point A and point B) is oscillated as shown in Fig. 3. The temperature rises rapidly, and the temperature inside the mold (point C and point D) hardly rises due to high-frequency induction heating. In the case of the example shown in FIG. 3, the mold is not cooled with cooling water, but simply shows an example of the change over time in the temperature distribution of the mold due to high-frequency induction heating. Thereafter, the molds 4 and 5 are opened once, the inductor 2 is extracted from between the fixed and movable molds 4 and 5, the mold is closed again, and the above-mentioned thermoplastic resin with filler is injected in the same manner as in normal injection molding. Performs injection molding. FIG. 4 shows an optical microscope observation sketch of the cut surface in the thickness direction of the injection molded product thus obtained. The magnification is 440x. For reference, the same material was injection molded using the same mold at a mold temperature of 60°C without using inductor 2, and the same cross section was similarly observed and sketched.
It is a diagram. The magnification is 440x. In both drawings, the island pattern is made of glass fiber, and the horizontal line is the surface of the molded product. As is clear from comparing FIG. 4 and FIG. 5, in the case of the molded product according to the present invention, the filler glass fiber A' does not appear on the surface of the molded product, and at least 1.
It can be seen that an amorphous thermoplastic resin B' layer of ~30μ is formed on the surface layer of the molded product. Also, as shown in Figure 4, when the glass fiber A' is located relatively close to the surface of the molded product, the thermoplastic resin B' layer forms the surface layer, and at the same time, due to the influence of the glass fiber A', there is a slight difference in the surface layer. Even if unevenness is formed, the unevenness is gentle compared to the case shown in FIG. 5, so that a molded product with a glossy appearance can be obtained. On the other hand, in the case of a normal molded product, as shown in Figure 5, if the glass fiber A' protrudes from the surface of the molded product, or if the glass fiber is near the surface layer, the flow of resin on the mold surface will be hindered. Otherwise, silver streak-like irregularities are formed on the surface, and only a molded product with a so-called dull and rough surface can be obtained. In order to quantify the good appearance and glossiness of the molded product of the present invention, the glossiness G _s (60°) of the molded product was measured according to ASTM D523, and the result was 98%.
It was hot. On the other hand, a molded product with a mold temperature of 60℃ has a gloss level of 45.
%, indicating the smoothness and gloss of the molded product appearance of the present invention. Also, perhaps because the molded product of the present invention has low flow resistance during injection molding and is less likely to cause orientation distortion, when the heat distortion temperature specified in JIS K6871 was measured, the heat distortion temperature was 3. The so-called practical heat resistance temperature is improved by ~5°C, and as a result of comparing the drop strength of molded products, the practical toughness is also improved. In this way, plating is applied to the surface of a molded product with improved surface smoothness and enhanced performance. We will also explain in detail the processing method. Example 1 A concave mirror type Fresnel lens type solar heat reflective heat collecting plate was injection molded using the above-mentioned apparatus using ABS resin to which 30% by weight of glass fiber was added. The mold was made of NAK material (cemented carbide mold steel) and was able to form a heat collector plate with outer dimensions of approximately 20 cm x 20 cm x depth of approximately 2 cm and an average wall thickness of 6 mm. The molded product forming surface of the mold has a mirror finish. The gate is a center direct gate mold. The inductor was made by arranging copper tubes with a diameter of 5 mm in a spiral disk shape at 10 mm intervals, and in order to fix it in this shape, it was cast with a non-magnetic resin (epoxy resin) and hardened into a flat plate. As for the injection molding conditions, the cylinder temperature was set so that the temperature of this glass fiber reinforced ABS resin was 240°C. Before injecting this glass fiber reinforced ABS resin into the mold, the above-mentioned inductor was sandwiched between the molds, and a high frequency oscillator of 7 KHz and 50 kW was used to
After oscillating for a second, the mold was opened, the inductor was pulled out from between all the molds, and the mold was closed again. In other words, just before injection molding the resin through this process,
The mold surface temperature was selectively heated to 120-130°C only near the mold surface by high-frequency induction heating.
This temperature is higher than the heating deformation temperature of the glass fiber-containing ABS resin, 103°C. However, the mold temperature within 3 to 5 cm from the mold surface was 50 to 60°C. The above-mentioned glass fiber-containing ABS resin was then injected into the mold with only the surface heated in this way at an injection pressure of 60 kg/cm ² for 10 seconds, and then cooling water was passed through the mold and cooled for 90 seconds. I took out the molded product. The entire molding cycle was 130 seconds. The surface of this molded product is extremely glossy, with a gloss level of G _s (60°)%.
It had a gloss level equivalent to that of a 98-100% molded product. Moreover, the R of the most important reflective surface of this molded product reproduced the R of the mold which had the designed R. In other words, the molded product had good mold surface transferability. The thus obtained molded product was plated in the next step using almost the same plating liquid as used for ABS resin plating. (1) Etching 70℃ 10 minutes (2) Neutralization 1 minute (3) Catalyst 1 minute (4) Acceleration 5 minutes (5) Chemical nickel 10 minutes (6) Activation 30 seconds (7) Strike nickel 1 minute ( 8) Electrolytic copper 40 minutes (9) Chrome plating 5 minutes The thickness of the plating layer was approximately 40μ. The performance of the heat collecting plate thus obtained was as shown in Table 1. As is clear from this table,
This heat collecting plate has good dimensional accuracy and dimensional stability. Therefore, there is little dimensional change whether the temperature is low or high, and the heat collection efficiency is stable and high. Also, due to the addition of glass fiber, the coefficient of linear expansion has increased from 8 to 10×10 ^-5 /℃ to 2×
10 ^-5 /℃, which is almost the same as the coefficient of linear expansion of copper, which is the main component of plated metal (1.9 x 10 ^-5 /℃). Reflector surface temperature during the day in midsummer
The plated layer does not peel off, even at temperatures of 120℃ and -30℃ at night in the middle of winter, resulting in a heat collection plate with excellent heat collection efficiency. The surface roughness of JIS B0601 was 12-S or less, and the best one was 1.5S or less. Comparative Example 1 A molded article having the same shape as in Example 1 was formed using an ABS resin containing no glass fiber by a conventional injection molding method (without heating the mold surface), and plated in the same manner. Its performance is shown in Table 1. Comparative Example 2 Same material as Example 1 (30% glass fiber mixed)
ABS resin) was injection molded using the same machine, but without the use of an inductor to heat the mold surface, and the resulting molded product was plated in the same way.
Its performance is shown in Table 1.

[Table] Example An automobile foil cap center was molded using the same material as in Example 1 using an injection molding machine using the mold heating method using the same inductor, and was plated using the same plating process. Its performance is shown in Table 2 along with comparative examples.

【table】 [Brief explanation of the drawing]

Fig. 1 is a conceptual side view of an injection molding machine that inserts an inductor used to manufacture the product of the present invention, Fig. 2 is a vertical sectional view of the mold and inductor, and Fig. 3 is the same as Fig. 1 and Fig. 3. FIG. 2 is a graph showing the temperature distribution of a mold in an injection molding machine, FIG. 4 is an enlarged sketch of a cut surface of a product of the present invention, and FIG. 5 is a similar drawing of a conventional product. 1... High frequency oscillator, 2... Inductor,
3... Injection cylinder part, 4, 5... Mold.

Claims (1)

[Scope of Claims] 1. A smooth skin layer made of ABS resin containing filler as a constituent material and formed by a mold with only the surface heated, and having a bonding interface made of only ABS resin that does not substantially contain the filler. An injection molded ABS resin plating product containing a filler, characterized by having a plating surface formed integrally during injection molding and applied on top of this skin layer. 2. The plated product according to claim 1, wherein the filler is glass fiber with a diameter of 5 to 20 μm, and the content thereof is 10 to 30% by weight. 3. The plated product according to claim 1, wherein the filler is an inorganic filler with an average size of 1 to 100 microns, and the content thereof is 20 to 80% by weight. 4. The plated product according to claim 3, wherein the inorganic filler is an inorganic material such as CaCO ₃ or glass beads, a metal or alloy such as Fe, Fe ₂ O ₃ , Al, or ZnO, or an oxide thereof. 5 The plated surface has a surface roughness of 12-S (JIS
B0601) A plated product according to any one of claims 1 to 4 below.