JPS6295345A - Molded article of resin - Google Patents

Abstract

PURPOSE:A molded article useful as high-quality interior or exterior materials having a complicated shape or containers, having harmonized appearance free from weld-mark, etc., obtained by blending a thermoplastic resin with specific particles. CONSTITUTION:100pts.vol. thermoplastic resin is blended with 0.02-3.0pts.vol. particles having 10-300mum average diameter equivalent and luster with 1/8-1 average shape ratio, to give a molded article having 0.05-10.0mu Ra surface roughness. Aluminum, tin, copper, stainless steel, etc., are used as the particles having luster.

Description

[Detailed Description of the Invention] [Field of Industrial Application] The present invention is applicable to cameras, VTRs, OA equipment, electric razors,
Concerning resin molded products that can be used for interior/exterior materials, containers, etc. of cosmetics, etc.

[Conventional technology]

Many molded products have been known in which a thermoplastic resin is mixed with, for example, metal particles as a filler to give a glossy appearance and then melt-molded. There are two types of these molded products depending on the shape of the gloss imparting particles. The first is a molded product that has a uniform metallic appearance over its entire surface by filling it with fine to ultrafine metal particles, as disclosed in Japanese Patent Application Laid-Open No. 58-37045. . When manufacturing this molded product by injection molding, the flow cross section of the molten resin in the mold is as shown in Figures 4 and 5. Since a layer 2 that does not contain the resin is formed, a weld mark 3 (FIG. 5) of only resin is formed at the joint of the flows. Since this weld mark does not contain metal particles, it absorbs light and appears black, seriously detracting from its appearance. Therefore, such molded products could not be used as high-grade molded products such as camera exterior covers.

The second type has an average equivalent diameter of 30 μm or more, and in this molded product, the shearing force of the flaky powder during kneading and molding of the resin and metal flaky powder causes the support to be destroyed. Destroyed 7i-
If the weld mark is destroyed, the weld mark on the molded product will be less noticeable, but if it is destroyed, the weld mark will become more conspicuous, as seen in the first type described above.

The particle size distribution of the aluminum flake powder before and after kneading and forming is shown in the sixth figure.
As shown in FIG. In this case as well, the weld mark becomes conspicuous, making it difficult to use it for high-grade molded products with complex shapes.

In addition to erasing weld marks, another technical issue in producing high-quality molded products is accurately determining the overall tone, including color tone, which is an important element that determines the appearance of molded products. It is to adjust to. In other words, in order to give the surface of a molded product a calm and moist appearance, conventionally,
Methods such as adding a gloss remover to resin and smoothing the surface of a molding die are known. However, in the method of removing gloss, it is extremely difficult to adjust the components, and it is difficult to form an appearance that matches the color tone. In addition, the method of finishing the mold surface is an effective means for adjusting the gloss of the molded product, but due to continuous molding, mold surface wear occurs, which gradually changes the appearance, and it is difficult to repeatedly improve the appearance. It was not possible to obtain a molded product. In addition, precise adjustment of the mold surface roughness and regular maintenance of the mold are required, which causes a decrease in productivity.

Therefore, in order to accurately adjust the tone of a molded product, finishing the mold surface alone is insufficient, and optimization by adjusting the components inside the molded product is required.

[Purpose and outline of the invention]

A first object of the present invention is to provide a resin molded product that eliminates appearance defects such as weld marks that are found in conventional resin molded products filled with gloss imparting particles.

The second purpose of the present invention is to eliminate such weld marks and create a calm and moist appearance (hereinafter referred to as low-tone appearance) that resembles a faint cloud in the white evening sky, which was previously unachievable. The object of the present invention is to provide a resin molded product that is provided with the following properties.

A third object of the present invention is to provide a resin molded product that has an excellent appearance and can be used for high-grade molded products with complex shapes such as camera exterior covers and VTR covers.

A fourth object of the present invention is to provide a resin molded product that has a high-grade appearance without requiring frequent maintenance of the mold surface and has good productivity.

The above-mentioned object is a book characterized by containing 0.02 to 3.0 parts by volume of particles having a gloss of 1 per 100 parts by volume of a thermoplastic resin, and having a surface roughness of 0.05 to 10.0 μRa. This is achieved by the resin molded product of the invention.

[Detailed description and examples of the invention]

The glossy particles used in the present invention (hereinafter referred to as glossy particles) have an average equivalent diameter of 10 to 300 μm, where the average equivalent diameter is the equivalent diameter of the arithmetic mean of the longest diameter and the shortest diameter of the glossy particles, This is the average value of this equivalent diameter for the test particle group. To measure the equivalent diameter, place the molded product or the molded product dissolved in a solvent on a glass plate and use a particle distribution analyzer Luzex (trade name, Nippon Regulator Co., Ltd.).
ff). In addition, the average shape ratio is the ratio of the longest diameter to the shortest diameter of particles, that is, (shortest diameter)/(
is the arithmetic mean of the longest diameter). To calculate the average shape ratio, a particle distribution measuring device such as Lusex can be used.

Assuming that the glossy particles are spheres, in a system where the distances between the centers of the spheres are all equally distributed, the average gap between the glossy particles is calculated by the following formula (
1).

In formula (1), D: Average gap between glossy particles R: Average equivalent diameter of glossy particles ■: The volume ratio of all glossy particles to the total volume of thermoplastic resin and glossy particles is determined by the degree of conspicuous weld marks. As the reed and D become larger, the weld mark becomes less noticeable. In other words, the width of the weld mark of a metallic mold is usually 30 mm.
Since it is less than μm, if D is made larger than 35 μm, the weld mark becomes less noticeable.

The optimum average equivalent diameter for D to be 35 μm or more and to exhibit a low tone appearance is 10 to 300 μm.

If the average equivalent diameter is less than 10 μm, weld marks will be noticeable and individual particles will be difficult to distinguish visually.
It simply changes the color tone.

If the average equivalent diameter exceeds 300 μm, the glossy particles will look like foreign matter, impairing the balance of appearance and making it impossible to obtain a funnel-like appearance. A particularly preferable range of the average equivalent diameter is 20 to Z
It is ooμm.

Further, the average shape ratio of the glossy particles used in the present invention is L~1
The reason for this is that if it is less than -, the glossy particles are likely to be destroyed during kneading and molding, and weld marks are likely to be noticeable. The average shape ratio is particularly preferably L~1.

Furthermore, the content of the glossy particles needs to be 0.02 to 3.0 parts by volume per 100 parts by volume of the thermoplastic resin, but may be as small as 0.1 to 1.0 parts by volume. preferable. If the amount of gloss particles is less than 0.02 parts by volume, the particles will be too sparse to form a tone. 3.
If the amount is more than 0 parts by volume, the color tone of the particles will determine the color tone of the molded article, making it impossible to create a 90-tone appearance.

Another essential condition for obtaining a low-tone appearance in the resin molded product of the present invention is that the surface roughness Ra (center line average roughness according to Japanese Industrial Standard JIS 0601) of the resin molded product is 0. 05 to 10.0 μRa. In the case of 0.05 μRa grooves, the surface is almost mirror-like, so the surface of the molded product is glossy, sparkling, and does not have a low-tone appearance. 1
0. If it exceeds OμRa, the surface roughness of the molded product becomes too noticeable, making it difficult to understand the effect of the glossy particles. 0.05μ
If it is in the range of Ra to 10.0 μRa, the effect of the glossy particles themselves and the effect of the surface roughness are in good harmony, and a low-tone appearance can be achieved satisfactorily. The surface roughness is more preferably 0.
This is the case of 2 to 3.0 μRa.

In addition, particularly preferable ranges for combinations of the average equivalent diameter of the glossy particles and Ra are shown as a graph in FIG. 1 (the shaded area is the preferable range).

The base material of the glossy particles used in the present invention does not matter as long as the particles have a glossy surface. For example, at least the surface layer is made of metals such as aluminum, soot, copper, or iron; alloys made of these metals such as brass or stainless steel;
Glossy particles made of mica, certain shells, inorganic or organic polymer crystals that exhibit birefringence, phosphors, etc. can be used.

For example, using aluminum particles will give you a silvery, sparkling appearance, and using brass particles will give you a golden, moist appearance. Moreover, various appearances can be formed by changing the gloss appearance of the surface of the metal particles.

Thermoplastic resins used in the present invention include, for example, acrylic resins, styrene resins, vinyl chloride resins, methylpentene resins, polycargenate resins, copolymerized polyesters,
They may be mixed with resins such as copolyamide and ABS, or may be colored. Further, the resin molded product of the present invention may be coated with a coloring agent of, for example, 0.1 parts by volume per 100 parts by volume of the resin.
By mixing ~12.0 parts by volume, more diverse appearances can be formed.

Furthermore, various stabilizers, release agents, antistatic agents, flame retardants, etc. that can be added to the thermoplastic resin can be added within a range that does not impair the effects of the present invention.

The resin molded article of the present invention is particularly effective when manufactured by injection molding or injection compression molding, but other melt molding methods such as extrusion molding may also be used.

It has been said for some time that silver streaks, which are a type of appearance defect, are likely to occur when molding with a metallic appearance, but it is important to keep the drying time at least 2 hours and to avoid lowering the mold temperature. If you follow these rules, silver streaks will not occur in the case of a galaxy-like appearance. In addition, in the case of a metal-like appearance, a pinpoint gate tends to cause silver streaks, but in the case of a galaxy-like appearance of the present invention, silver streaks do not occur even with pinpoint darts.

The thermoplastic resin and the glossy particles are preferably used in a composition obtained by melting the resin in advance and mixing them, for example, in the form of pellets, or in order to uniformly disperse the glossy particles in the molded product.

EXAMPLES The present invention will be explained in more detail with reference to Examples below.

Example 1 Using 100 parts by volume of polycarnate resin containing titanium oxide, carbon black, etc. and 0.5 parts by volume of aluminum particles (average equivalent diameter 38 μm, average shape ratio V32),
Mold surface roughness: 0.56Ra, 4.2Rmax +
A camera front cover shown in FIG. 2 was molded at 3.6 Rtm.

Molding conditions Cylinder temperature 295, 290, 285, 2
30°C injection pressure 1300 kg7cm2 Total 7c degrees 110-115°C The obtained molded product had no weld marks and had a moist, low-tone appearance like a white evening sky.

Examples 2 and 3 The average equivalent diameter of the aluminum particles used was 75 μm or 210 μm.
A molded article was obtained in the same manner as in Example 1 except that the diameter was changed to μm. The obtained molded product had no weld marks as in Example 1 and had a low-tone appearance.

Examples 4 and 5 Molded articles were obtained in the same manner as in Example 1, except that the content of aluminum particles was changed to 0.1 part by volume or 1.6 parts by volume based on 100 parts by volume of polycarbonate resin.

The obtained molded product had no weld marks as in Example 1 and had a low-tone appearance.

Examples 6 and 7 Molded products were obtained in the same manner as in Example 1, except that the average shape ratio of the aluminum particles was changed to 1/7.2 or 1/1.4.

The obtained molded product had no weld marks as in Example 1 and had a low-tone appearance.

Examples 8 and 9 The surface roughness of the mold was set to (0.13 μRa, 1.2 μR
max.

9,4 μRtm) or (4,1 μRa, 21.
A molded article was obtained in the same manner as Example 1 except that the values were changed to 8 μRmax and 18.0 μRtm. The obtained molded product had no weld marks as in Example 1 and had a low-tone appearance.

Comparative Example 1 PPO resin 1 containing titanium oxide, carden black, etc.
00 parts by volume and 3.5 parts by volume of aluminum particles (average equivalent diameter 5.0 parts by volume).
The mold surface roughness was 0.02 μRa, 0.36 μRtm,
The VTR upper cover shown in FIG. 3 was molded with a value of 0.42 μRmlLX.

Molding conditions Cylinder temperature 260, 260, 255, 2
10°C Injection pressure: 870 kgf/cm2 Mold temperature: 70-75°C The obtained molded product not only did not have a sparkling metallic appearance, but also did not have the appearance of the mouth and tone required by the present invention, and also had poor welding. Also, it could not be used for high-quality appearance products.

Example 10 PPO resin 10 containing titanium oxide, cyanine blue, etc.
0 part by volume and 1.0 part by volume of brass particles (average equivalent diameter 72 μm
) with a mold surface roughness of 0.82Ra.

6.7 Rmax + 4.3 Rtm, and a VTR upper cover shown in FIG. 3 was molded.

Molding conditions Cylinder temperature 270, 270, 265.2
10°C Injection pressure: 950 kg7cm2 Total: 7°C 70-75°C The molded product obtained had no weld marks and had a moist, low-tone appearance like a white sky.

〔Effect of the invention〕

The resin molded product of the present invention has no weld marks and exhibits a low-tone appearance that can be used for high-grade molded products such as camera exterior covers and OA equipment exteriors, which was previously unachievable.
It becomes possible to expand the boundaries of glass snack exterior design. In particular, the effect is remarkable when dye-colored thermoplastic resin is used, and it can be applied to products with complex shapes.

In addition, frequent maintenance of the mold surface is reduced, productivity is improved, and the defective rate is reduced. this is,
Unlike the conventional method of creating a matte appearance only by finishing the mold surface, in the case of the present invention, by combining the adjustment of the conditions of the glossy particles and the adjustment of the surface roughness (finishing of the mold surface), This is achieved by eliminating the need for sudden changes in the appearance of the molded product due to abrasion of the mold surface. This also makes it possible to shorten the molding cycle.

[Brief explanation of drawings]

Diagram M1 is a graph showing the average equivalent diameter of glossy particles and the preferred range of molded product surface roughness in the present invention. FIGS. 2(a) to 2(d) are a plan view, a front view, a left side view, and a right side view, respectively, of a camera exterior cover according to the present invention. FIGS. 3(e) to 3(g) respectively show the VT according to the present invention.
They are a top view, a front view, and a left side view of the R exterior cover. Figure 4 shows the flow of conventional metal-filled resin, Figure 5 is a sectional view of metal-filled resin after molding, and Figures 6 and 7 show molding using glossy particles with an average shape ratio of 1/10 or less. It is a graph showing particle size distribution (frequency distribution) before and after. 1... Metal powder, 2... Layer only of resin, 3... Queld mark. @Figure 1 Surface bundle 1 Ra (4m) Figure 2 Figure 3 (8) (e)

Claims (1)

[Claims] (1) Contains 0.02 to 3.0 parts by volume of glossy particles with an average equivalent diameter of 10 to 300 μm and an average shape ratio of 1/8 to 1 per 100 parts by volume of thermoplastic resin, and has a surface roughness. A resin molded product characterized by having an Ra of 0.05 to 10.0 μRa.