JPH0699593B2 - Resin molded product - Google Patents

Description

TECHNICAL FIELD The present invention relates to a resin molded product used for an interior / exterior material such as a camera, a VTR, an OA device, an electric razor, and a cosmetic, a container, and the like.

[Prior Art] Conventionally, many molded products have been known in which, for example, metal particles are mixed and melt-molded as a filler for imparting a glossy appearance with a thermoplastic resin. There are two types of these molded products depending on the shape of the gloss-imparting particles. The first one is a molded article which is filled with fine or ultrafine metal particles as disclosed in Japanese Patent Application Laid-Open No. 58-37045 and has a uniform metallic or metallic appearance on the entire surface. .
When this molded product is manufactured by injection molding, the flow cross section of the molten resin in the mold is, as shown in FIGS. 2 and 3, in the flow process (FIG. 2), at the tip of the flow of metal particles. Since the layer 2 which is not included is formed, the weld mark 3 (FIG. 3) made of only resin is formed at the joint between the flows. Since this weld mark does not contain metal particles, it absorbs light and appears black, and the appearance is significantly impaired. Therefore, such a molded product cannot be used as a high-grade molded product such as a camera exterior cover.

The second type is an average equivalent diameter of 30 μm or more and an average shape ratio of 1 /
It uses a metal flaky powder of 10 or less. In this molded product, the flaky powder is destroyed by the shearing force during the kneading and molding of the resin and the flaky metal powder. If not destroyed
Weld marks on molded products are less noticeable, but when destroyed, as seen in the first type,
As a result, the weld mark becomes more noticeable.

Incidentally, FIGS. 4 and 5 show the particle size distribution of aluminum flaky powder having an average equivalent diameter of 50 μm and an average shape ratio of 1/10 or less before and after kneading and molding. Also in this case, the weld mark becomes conspicuous, and it is difficult to use it in a high-quality molded product having a complicated shape.

[Object and Summary of Invention]

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

A second object of the present invention is to eliminate such a defect in appearance, and to have an excellent appearance that can be used for high-quality molded products such as camera exterior covers and VTR covers, that is, to be shined by being scattered in a clear night sky. It is to provide a resin molded product having a galactic-like (hereinafter, galactic-like) appearance.

The above object is to use a composition containing 0.1 to 5.0 parts by volume of particles having a gloss of an average equivalent diameter of 30 to 250 μm and an average shape ratio of 1/8 to 1 with respect to 100 parts by volume of a thermoplastic resin. When molding with a mold, a resin molded product formed so that the compositions are combined with each other in the mold, the occupied area of the particles having the gloss as viewed from the surface of the resin molded product is 0.5 to 0.5 of the total surface area. It is achieved by the resin molded product of the present invention characterized by 16.0% and no weld mark.

[Detailed Description of the Invention and Examples] The particles having gloss (hereinafter referred to as gloss particles) used in the present invention are particles having an average equivalent diameter of 20 to 500 μm.

Here, the average equivalent diameter refers to a value obtained by averaging the equivalent diameters of the test particle groups with the arithmetic mean of the longest diameter and the shortest diameter of the gloss particles being the equivalent diameter. To measure the equivalent diameter, place the molded article or the molded article in a solvent on a glass plate,
It can be carried out using a particle distribution measuring device Luzex (trade name, manufactured by Nippon Regulator Co., Ltd.).

If the average equivalent diameter of the glossy particles is less than 30 μm, it is difficult to distinguish each glossy particle by eye, so when trying to obtain a metallic appearance, the area occupied by the glossy particles becomes too large and the weld line is Let's stand out. 250μ
When it exceeds m, each particle becomes too conspicuous and spoils the high-class feeling. The average equivalent diameter of the glossy particles is 30 to 250 μm.

The occupied area of the glossy particles viewed from the surface of the resin molded product can be measured, for example, by hanging the molded product on the LUZEX and discriminating between the glossy particles and the resin in the vicinity of the surface of the molded product.

Generally, the area occupied by the glossy particles is greatly influenced by the light transmittance of the molded product.

For example, when uncolored polycarbonate resin is filled with aluminum particles, since all the particles are visible from the surface of the molded product, the occupied area often exceeds 80%.

However, when the polycarbonate resin is colored with carbon black, the surface visible is 10 to 200 μm from the surface layer.
Limited to

Assuming that the glossy particles are spheres, the average spacing of the glossy particles is (1)
It is represented by a formula.

D: Average gap of glossy particles R: Average equivalent particle size of glossy particles V: Volume ratio of all glossy particles to total volume of thermoplastic resin and glossy particles When the light transmission range is D, the occupied area ratio is theoretically In the case of ordinary coloring, the light transmission range is about 10 to 300μ.
Since it is m, the weld line is not conspicuous if the occupied area is 16.0% or less. If it is less than 0.5%, the effect of adding glossy particles is difficult to discern. Therefore, 0.5-1
6.0% is desirable. It is preferably in the range of 2.0 to 10.0%.

In order to obtain such an area occupied by the glossy particles, the content of the glossy particles in the resin molded product is 0.1 to 100 parts by volume of the resin.
Select within the range of 5.0 parts by volume.

The average shape ratio of the glossy particles is 1/8 to 1. Here, the average shape ratio is a ratio of the longest diameter and the shortest diameter of the particles, that is, an arithmetic average of (shortest diameter) / (longest diameter). For the calculation of the average shape ratio, the particle distribution measuring device Luzex or the like can be used. If the average shape ratio is less than 1/8,
During kneading and molding, the glossy particles are likely to be broken, and the weld mark is apt to stand out. The average shape ratio is particularly preferably 1/3 to 1.

The base material of the glossy particles used in the present invention is not limited as long as it has a glossy surface. For example, at least the surface layer portion is a metal such as aluminum, tin, copper, or iron, brass using these metals as a substrate, an alloy such as stainless steel,
It is possible to use glossy particles made of mica, some kinds of shells, inorganic or organic polymer crystals that cause birefringence, and phosphors.

For example, the use of aluminum particles provides a silvery, glittery appearance, and the use of brass particles provides a golden, moistened appearance. Also, various appearances can be formed by changing the gloss appearance of the surface of the metal particles.

The resin used in the present invention is, for example, an acrylic resin,
Polystyrene resins, polyolefin resins such as polypropylene, vinyl chloride resins, methylpentene resins, polycarbonate resins, copolyesters, copolyamides, thermoplastic resins such as ABS may be mixed together or colored. Alternatively, elastomers can be used. Further, by mixing the resin molded product of the present invention with a coloring agent in an amount of 0.1 to 12.0 parts by volume with respect to 100 parts by volume of the resin, more various appearances can be formed.

Further, various stabilizers, mold release agents, antistatic agents, flame retardants and the like which can be blended with the thermoplastic resin can be added within a range that does not impair the effects of the present invention.

The resin molded product of the present invention exerts a particularly advantageous effect when manufactured by injection molding or injection compression molding, but other melt molding methods such as extrusion molding may be used.

It has been said that silver streak, which is one of the poor appearances, is likely to occur in the molding of metallic appearance, but it is necessary to set the drying time to 2 hours or more and not to lower the mold temperature. If you observe the above, silver streaks will not occur in the case of galactic appearance. Further, in the case of the metallic appearance, the pinpoint gate easily causes silver streak, but in the case of the galactic appearance of the present invention, the silver streak does not occur even in the pinpoint gate.

It is preferable to use the thermoplastic resin and the glossy particles as a composition in which the resin is melted and mixed in advance, for example, as a pellet because the glossy particles are uniformly dispersed in the molded article.

Hereinafter, the present invention will be described more specifically with reference to examples.

Example 1 A front cover of a camera shown in FIG. 1 was molded using 100 parts by volume of a polycarbonate resin containing a coloring agent (carbon black or the like) and 1 part by volume of aluminum particles (average equivalent diameter 43 μm).

The area occupied by the aluminum particles in the molding conditions Cylinder temperature 295,290,285,230 ° C. injection pressure 1450kg / cm ² type temperature 120-125 ° C. The resulting resin molded article surface was 6.2% of the total surface area. This molded product had a high-grade metallic appearance without any defective appearance such as weld lines.

Examples 2 and 3 The average equivalent diameter of the aluminum particles used was 80 μm or 210 μm.
A molded product was obtained in the same manner as in Example 1 except that the above was changed. The obtained molded product had no weld mark and had a high-grade metallic appearance as in Example 1.

Examples 4, 5 A molded product was obtained in the same manner as in Example 1 except that the content of aluminum particles was adjusted to change the occupied area viewed from the surface of the molded product to 1.2% or 14.5%. The obtained molded product had no weld mark and had a high-grade metallic appearance as in Example 1.

Comparative Example 1 100 parts by volume of a polycarbonate resin containing a colorant (such as carbon black) and aluminum particles (average equivalent diameter 2.4 μ)
m) A resin molded product was obtained in the same manner except that 6 parts by volume of the material was used.

The area occupied by aluminum particles was almost 100%, and welds were conspicuous, so that it could not be used for high-grade appearance molded products.

〔The invention's effect〕

The resin molded product of the present invention has no weld mark and has a low-tone appearance that can be used for high-grade molded products such as camera exterior covers and OA equipment exteriors, which could not be achieved conventionally, and expands the frame of plastic appearance design. Is possible. In particular, when a dye-colored thermoplastic resin is used, its effect is remarkable, and it can be applied to a product having a complicated shape.

[Brief description of drawings]

1A to 1D are a plan view, a front view, a left side view and a right side view of a camera exterior cover according to the present invention, respectively. FIG. 2 is a flow cross-sectional view of a conventional metal-filled resin, FIG. 3 is a cross-sectional view of a metal-filled resin after molding, and FIGS. 4 and 5 show the case where gloss particles having an average shape ratio of 1/10 or less are used. 6 is a graph showing a particle size distribution (frequency distribution) before and after molding. 1 ... Metal powder, 2 ... Layer of resin only, 3 ... Weld mark.

Claims (1)

[Claims] 1. A composition containing 0.1 to 5.0 parts by volume of particles having an average equivalent diameter of 30 to 250 μm and a gloss having an average shape ratio of 1/8 to 1 with respect to 100 parts by volume of a thermoplastic resin. When molding with a mold, a resin molded product formed such that the compositions are combined in the mold, the occupied area of the particles having the gloss as viewed from the surface of the resin molded product is 0.5 of the total surface area. Resin molded product characterized by ~ 16.0% and no weld mark.