JPS6258291B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to so-called bath and toiletry products for use around water, which are made of a thermoplastic resin containing a filler and are injection molded with a good appearance. Bath and toiletry items include towel hangers, soap trays, vanity shelves, toothbrush holders,
Bath products such as bathtubs, hand showers, wash bowls, toilet seats, toilet lids, toilet paper holders,
A general term for toiletry items such as water tanks. Thermoplastic resins have the general properties of being easy to mold, can be easily molded into complex shapes, and can be mass-produced in the same shape, as well as having the advantage of being water resistant. Therefore, it has been used as injection molded products in bath and toiletry products. However, such plastic injection molded products have poor appearance (absolute value and uniformity of gloss), rigidity, heat resistance, etc. compared to ceramics, tiles, or gel-coated FRP products that have traditionally been used for this purpose. Because of its inferiority, the scope for practical use was limited. On the other hand, thermoplastic resins containing fillers are available as materials that improve the rigidity and heat resistance required for this application.
Since the filler is not thermoplastic and the compatibility between the filler and the thermoplastic resin is poor, voids are created between the respective materials. Therefore, when injection molding is performed, the surface of the molded product is rough and the appearance is poor, so it is not used for this purpose. The present invention has focused on this point, and aims to provide injection molded bath and toiletry products that use a filled thermoplastic resin that inherently has excellent properties and that have improved appearance. That is, the present invention provides bath and toiletry products made by injection molding of filled thermoplastic resin that require a good appearance, in which the filled thermoplastic resin has a water absorption rate of 0.5% or less, and substantially A bath/toiletry article characterized in that a skin layer of the thermoplastic resin containing no filler is formed. According to the present invention, in combination with the selection of a thermoplastic resin that inherently has a low water absorption rate, the relatively high water absorption rate found in conventional filled thermoplastic resins is significantly reduced. The reason for this is not clear, whether it is because the surface becomes smooth and the water absorption surface area is reduced, or because the vicinity of the surface is substantially covered with the thermoplastic resin, but it is significant for this purpose. The present invention will be described in further detail below with reference to 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 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. Thermoplastic resins for injection molding include, for example, acrylonitrile-styrene copolymer (AS resin),
Acrylonitrile-butadiene-styrene copolymer, acrylonitrile-butadiene-styrene
α-Methylstyrene, acrylonitrile-methylmethacrylate-butadiene-styrene (ABS
thermoplastic resins with a water absorption rate of 0.5% or less, such as styrene resins such as polystyrene, and polyphenylene ether (PPE). In addition, the filler mixed in with this is 5 to 20 mm in diameter.
5-40% by weight of μ glass fiber, preferably 10-40% by weight
30% by weight. Furthermore, as another filler,
CaCO ₃ , inorganic substances such as glass beads, and Fe,
Examples include metals and alloys such as 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 100μ.
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, the temperature only 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. After that, the molds 4 and 5 are opened once, the inductor 2 is extracted from between the fixed side and movable side molds 4 and 5, the mold is closed again, and the above-mentioned heat-filled filler is heated in the same manner as normal injection molding. Performs injection molding of plastic resin. 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 glass fiber, and the horizontal line is the surface of the molded product. As is clear from comparing Figures 4 and 5,
In the case of molded products according to the present invention, filler glass fiber
It can be seen that A' does not appear on the surface of the molded product, and that an amorphous thermoplastic resin B' layer of at least 1 to 30 μm is formed on the surface of the molded product. Furthermore, as shown in Fig. 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', the surface layer slightly changes. Even if the unevenness is formed, the unevenness is gentle compared to the case shown in FIG. 5, so that a molded product having 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 A' is near the surface layer, that is, the resin flows on the mold surface. Perhaps due to the alienation of silver streak-like irregularities on the surface, only molded products with so-called dull and rough surfaces can be obtained. In order to quantify the appearance and gloss of the molded product of the present invention, the gloss level Gs (60
As a result of measuring ゜), it was 98%. On the other hand, the molded product produced at a mold temperature of 60° C. had a gloss level of 45%, indicating that the molded product of the present invention had a smooth appearance and good gloss. In addition, the molded product of the present invention has less flow resistance during injection molding and is less prone to orientation distortion.
When we measured the heating deformation temperature specified in JIS K6871, we found that the heating deformation temperature was 3.
As a result of comparing the drop strength of molded products, the so-called practical heat resistance temperature is improved by ~5°C, and the practical toughness is also improved. Example 1 A heated toilet seat shown in FIG. 6 was made by injection molding using ABS resin to which 20% by weight of glass fiber was added. The mold uses NAK material (super hardened alloy mold steel), and the molded product forming surface of the mold has a mirror finish. The inductor is made by arranging 5 mm diameter steel pipes in a spiral or flat shape to match the shape of the mirror-finished part of the mold, and then casting and solidifying it with a non-magnetic resin (epoxy resin) to fix the shape. did. As for the injection molding conditions, the cylinder temperature was set so that the temperature of the glass fiber reinforced ABS resin was 240°C. Before injecting the glass fiber reinforced ABS resin into the mold, the above-mentioned inductor is inserted between the molds, oscillated for 15 seconds by a 400KHz, 75KW high frequency oscillator, then the mold is opened, and the inductor is inserted between the molds. It was pulled out and the mold was closed 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 selectively increase the temperature of the surface of the mold just before the resin is injected into the mold. The temperature was 120°C to 130°C to heat the mold, but the mold temperature within 3 to 5 cm from the mold surface was 50 to 60°C. Then, like normal injection molding, the resin was injected into the mold at an injection pressure of 60 kg/cm ² for 15 seconds.
The molded product was taken out after a cooling time of 50 seconds. The entire molding cycle was 90-95 seconds. Table 1 shows the results of comparing the practical performance of this toilet seat. As shown in Table 1, it has excellent practical performance such as rigidity and heat resistance, has good practical test results, and has a high gloss and uniform appearance, making it a practical product that does not look out of place with other ceramic parts. I also got an excellent toilet seat. Comparative Example 1 Using the same resin, the same mold, and the same molding machine as in Example 1, the performance of the heated toilet seat was evaluated in the same manner as in Example 1. Shown in the table. Comparative Example 2 The performance of a heated toilet seat molded under the same conditions as Comparative Example 1 except that ordinary ABS resin without glass fibers was used instead of the glass fiber-reinforced ABS resin of Comparative Example 1 was evaluated. It is shown in Table 1.

[Table] Example 2 A housing for a bubble generator that generates bubbles in a bathtub was manufactured using glass fiber-containing AS resin by injection molding using the method described in Example 1, in which the mold surface was heated by high-frequency induction heating. Ivy. As a control, products with the same shape were made using conventional injection molding using polypropylene (PP), ABS resin, and glass fiber-containing AS resin, and their performance was compared. The results are shown in Table 2.

【table】

[Table] Example 3 A marble-like heavy-walled soap saucer shown in Figure 7 (height 12cm, width 15cm, height 3cm, maximum wall thickness 15cm)
mm, average wall thickness 8 mm) was made using glass fiber-containing AS resin by injection molding using the method described in Example 1 in which the mold surface was heated by high-frequency induction heating. As a control, products with the same shape were made using conventional injection molding using AS resin, ABS resin, and glass fiber-containing AS resin, and their performance was compared. The results are shown in Table 3.

Table 4 Generally, the performance of the bath and toiletry products according to the present invention and conventional injection molded bath and toiletry products is compared in Table 4.

【table】 [Brief explanation of the drawing]

FIG. 1 is a conceptual side view of an inductor insert type injection molding machine used for manufacturing the product of the present invention.
Figure 2 is a vertical sectional view of the mold and the inductor, Figure 3 is a graph showing the temperature distribution of the mold in the injection molding machine shown in Figures 1 and 2, and Figure 4 is the product of the present invention. 5 is a similar drawing of a conventional part, FIG. 6 is a back view of a toilet seat embodying the present invention, and FIG. 7 is a perspective view of a soap tray embodying the present invention. 1... High frequency oscillator, 2... Inductor,
3... Injection cylinder part, 4, 5... Mold.

Claims (1)

[Scope of Claims] 1. Bath and toiletry products made by injection molding of filled thermoplastic resin that require good appearance, in which the water absorption rate of the filled thermoplastic resin is 0.5.
% or less, and the skin layer of the thermoplastic resin substantially free of filler is integrally formed during injection molding without a bonding interface. 2. The bath/toiletry 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 bath/toiletry product 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. Bath and toiletry products 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, ZnO, or an oxide thereof. . 5. The bath/toiletry article according to claim 1, wherein the thermoplastic resin is a styrene resin such as polystyrene, acrylonitrile-butadiene-styrene resin, or acrylonitrile-styrene resin. 6. The bath/toiletry article according to claim 1, wherein the thermoplastic resin is polyphenylene ether. 7 Surface glossiness (Gs (60°)%/ASTM D523)
80% or more of the bath and toiletry products according to claim 1.