JPS6258292B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a vehicle part injection molded from a thermoplastic resin containing a filler and having a good appearance. Thermoplastic resins are easy to mold and process;
Even complex shapes can be easily formed.
Furthermore, it has the general property that objects of the same shape can be mass-produced. In particular, many vehicle parts have been made of thermoplastic resins because they offer properties such as improved vehicle fuel efficiency due to weight reduction and improved corrosion resistance (no rust). On the other hand, if the following properties of thermoplastic resin vehicle parts are improved, the use of thermoplastic resin will be further promoted.
It is expected that vehicle performance will improve. (b) Improved strength and rigidity. (b) Improved heat resistance. (c) Improved dimensional stability. (d) Improving vibration resistance specific to vehicle parts. Filled thermoplastic resin fulfills each of (a) to (d) above and is a preferable material for vehicle parts, but the filler is not thermoplastic and the compatibility between the filler and thermoplastic resin is poor. Due to the poor quality, the surface is rough when injection molded, probably due to the formation of voids between each material, and the appearance is poor, so it has not been put to practical use. Although there are some examples of instrument panels being put into practical use by painting them, the cost is high, and some components of the paint (for example, thinner)
Since the resin melts, properties such as impact resistance deteriorate. Accordingly, an object of the present invention is to provide a filled thermoplastic resin injection molded vehicle part that does not have such problems in appearance and can be used as is without painting or the like. That is, the present invention provides thermoplastic resin injection-molded vehicle parts with fillers that require good appearance, in which the thermoplastic resin is heated to HDT (Heat Distortion Temperature, JIS
K6871) Thermoplastic resin with a temperature of 80℃ or higher,
The present invention provides a vehicle component characterized in that a skin layer of the thermoplastic resin is formed which substantially contains no filler. DESCRIPTION OF THE PREFERRED EMBODIMENTS Preferred embodiments of the present invention will be described in detail below as illustrated in the accompanying drawings. 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 is constituted by a high frequency induction heating beam consisting of an oscillating device 1 and an inductor 2 connected to the oscillating device 1 and placed near the mold surface. Thermoplastic synthetic resins for injection molding include, for example, acrylonitrile-styrene copolymer (AS resin), acrylonitrile-butadiene-styrene copolymer, acrylonitrile-butadiene-styrene-α-methylstyrene, and acrylonitrile-styrene copolymer.
Methyl methacrylate-butadiene-styrene,
Acrylonitrile - ethylene propylene rubber -
Styrene copolymer, acrylonitrile-butyl acrylate rubber-styrene copolymer (generally referred to as ABS resin) polystyrene, polyphenylene ether,
Thermoplastic resins with an HDT of 80°C or higher, such as polyamide, polyoxymethylene, polycarbonate, polyethylene, polypropylene, and polybutylene terephthalate. Among these, particularly preferred are:
Styrenic resins such as AS resin, ABS resin, and PPE
It is resin. The filler to be mixed into this is 5 to 40% by weight, preferably 15 to 30% by weight of glass fibers having a diameter of 5 to 20μ. Further fillers include inorganic materials such as CaCO ₃ , glass beads, and
Examples include metals and alloys such as Ee, Fe ₂ O ₃ , Al, and Zno, and their oxides. The average particle size of such inorganic materials is 1 to 100μ, and the amount of inorganic filler is
20 to 80% by weight. Such a material is injection molded, and at this time, as shown in the enlarged sectional view of FIG. 2, an inductor 2 for high-frequency induction heating is installed between the stationary mold 4 and the movable mold 5. When the inductor 2 is sandwiched between the movable mold 5 and the stationary mold 4 and a high frequency is oscillated in the sandwiched state, the third
As shown in the figure, only the temperature on the surface of the mold (points A and B) rises rapidly, and the temperature inside the mold (points C and 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 containing filler is injected in the same manner as 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 the inductor 2, and the same cross section was similarly observed and sketched in FIG. 5. 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 of the present invention, the filler glass fibers A' do not appear on the surface of the molded product, and at least 1~
It can be seen that a 30μ thermoplastic resin B' layer is formed on the surface 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, even if the thermoplastic resin B' layer forms some unevenness on the surface layer, compared to the case in Figure 5. A molded product having a glossy appearance due to its gentle unevenness is 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 molding surface, or if the glass fiber A' is near the surface layer, the flow of resin on the mold surface will be hindered. Because of this, silver streak-like irregularities occur on the surface, and only molded products with so-called dull and rough surfaces can be obtained. In order to quantify the good appearance and gloss of the molded product of the present invention, the gloss Gs (60°) of the molded product was measured according to ASTM D523, and the result was 98%. On the other hand, the molded product produced at a mold temperature of 60°C had a gloss level of 45%, demonstrating 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 to 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. Example 1 AES resin added with 20% by weight of glass fiber (acrylonitrile-ethylene propylene rubber-styrene copolymer resin commonly known as weather-resistant ABS resin)
The fender mirror body of a passenger car shown in FIG. 6 was injection molded using the same. The mold uses NAK material (carbide mold steel), and the molded product forming surface of the mold has a mirror finish. The inductor is made of a 5mm diameter steel tube that is arranged in a spiral shape to match the shape of the mirror-finished part of the mold, and is made of non-magnetic resin (epoxy resin) to fix the shape.
It was cast and solidified. As for the injection molding conditions, the cylinder temperature was set so that the temperature of the glass fiber reinforced AES resin was 250°C. Before injecting the glass fiber reinforced AES resin into the mold, the above-mentioned inductor was inserted between the molds and oscillated for 15 seconds using a 7KHz, 25KW high frequency oscillator, then the mold was opened and the inductor was extracted from between the molds. , and closed the mold again. In this injection molding process, the surface of the mirror-finished mold on which the molded product is to be formed is heated by high-frequency induction heating to select the surface temperature of the mold surface immediately before the resin is injected into the mold. Although the temperature was 120°C to 130°C to heat the mold, the temperature within 3 to 5 cm from the mold surface was 50 to 60°C. Thereafter, the resin was injected into the mold for 10 seconds at an injection pressure of 60 kg/cm ² in the same manner as in ordinary injection molding, and the molded product was taken out after a cooling time of 40 seconds. The entire molding cycle was 75-80 seconds. A fender mirror was assembled using the fender mirror body, and the results of a vibration test were good as shown in Table 1, and the appearance was very high gloss and uniform, making it compatible with glass fiber reinforced thermoplastic resin. In addition, the fender mirror was free of flow marks, silver streaks, jet extensions, etc., and the exterior was fully usable without the need for painting. Comparative Example 1 The same resin, same mold, and molding material as in Example 1 were used, and the performance of the fender mirror was similarly evaluated in the first example when not only the process of preheating the mold surface by high-frequency oscillation but also other molding conditions were the same. Shown in the table. Comparative Example 2 The performance of a fender mirror made under the same conditions as Comparative Example 1 was also the same, except that instead of the glass fiber reinforced AES resin of Comparative Example 1, an AES resin that was not reinforced with glass fiber, that is, without glass fiber added, was used. are shown in Table 1.

【table】

[Table] Example 2 Using a resin with 20% glass fiber added to ABS with an HDT of 85°C, injection molding was carried out using the method described in Example 1 in which the mold surface was heated by high-frequency induction heating.
We manufactured a lid with a defroster nozzle for the windshield of an automobile that is 6 cm wide and 1.2 m long. As a comparative example, HDT78 was made by injection molding using the same high-frequency induction heating.
A similar molded product was obtained using a resin containing 20% glass fiber added to ABS at ℃. In addition, as another comparative example, by conventional injection molding, a glass fiber-free product was
ABS resin with HDT 90℃, resin with 20% glass fiber added to ABS with HDT 78℃, and ABS with HDT 85℃
The same molded product was made from a resin with 20% glass fiber added. The performance test results are shown in Table 2.

TABLE In general, the performance of vehicle parts according to the invention and conventional injection molded vehicle parts is compared in Table 3.

[Table] Vehicle parts here specifically include automobile parts such as instrument panels, front extension panels, door locks, front grilles, fender mirror bodies, and wind regulator handles. It generally includes parts for vehicles such as automobiles, motorbikes, buses, and trucks.

[Brief explanation of the drawing]

Fig. 1 is a conceptual side view of an inductor insert type injection molding machine used for manufacturing parts of the present invention, Fig. 2 is a vertical cross-sectional view of the mold and inductor, and Fig. 3 is a cross-sectional view of the inductor insert type injection molding machine used for manufacturing parts of the present invention. A graph showing the temperature distribution of the mold in the injection molding machine shown in the figure, Figure 4 is an enlarged sketch of the cut surface of the part of the present invention, Figure 5 is a similar drawing of the conventional part, and Figure 6 is the figure of the present invention. FIG. 2 is an exploded perspective view of a fender mirror body that has undergone the above steps. 1... High frequency oscillator, 2... Inductor,
3... Injection cylinder part, 4, 5... Mold.

Claims (1)

[Claims] 1. In a filled thermoplastic resin injection molded vehicle part that requires good appearance, the thermoplastic resin is a thermoplastic resin with an HDT of 80°C or higher, and the surface glossiness (Gs ( 60゜)%/ASTMD523)
is more than 80%, fatigue limit (ASTMD671) is 3.0Kg/
mm ² or more, preferably 3.5 Kg/mm ² or more, and the skin layer of the thermoplastic resin containing substantially no filler is integrally formed during injection molding without a bonding interface. and vehicle parts. 2. The vehicle component according to claim 1, wherein the filler is glass fiber with a diameter of 5 to 20 μm, and the content thereof is 15 to 30% by weight. 3. The vehicle component according to claim 1, wherein the filler is an inorganic filler with an average particle size of 1 to 100 μm, and the content thereof is 20 to 80% by weight. 4. The vehicle component 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 vehicle component according to claim 1, wherein the thermoplastic resin is a styrene resin such as polystyrene, acrylonitrile-styrene resin, or acrylonitrile-butadiene-styrene resin. 6. The vehicle component according to claim 1, wherein the thermoplastic resin is polyphenylene ether.