JP2694501B2 - Synthetic resin composition - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION The present invention relates to a synthetic resin molded product such as an exterior plate for household electric appliances, a wall material for building interiors, a container for cosmetics, etc., and particularly, a synthetic product having a glittering and star-like appearance in the night sky. The present invention relates to a synthetic resin composition for obtaining a resin molded product.

[0002]

2. Description of the Related Art Japanese Patent Publication No. 57-40181 and Japanese Examined Patent Publication No. 4-27932 disclose a synthetic resin composition obtained by mixing fine particles of metal such as aluminum with a synthetic resin at a predetermined ratio. In such a synthetic resin composition, when the size of the metal fine particles is selected and the mixing ratio of the metal fine particles to the synthetic resin is selected, when the synthetic resin molded product thus obtained is viewed, the dispersed metal fine particles are glittered. , Which contributes to the improvement of appearance.

[0003]

In the molded product whose primary importance is the appearance as described above, the first problem is the appearance of the weld line. Generally, when a molded product has a hole, a weld line is prominent in a portion where the molten material goes around the hole and rejoins. In order to suppress the occurrence of this weld line, "molding conditions" such as increasing the cylinder temperature and mold temperature and the injection speed of the molten material, or "product design" such as changing the gate position are taken as measures. There is. That is a meaningful assumption.

However, in the resin molded product prepared by mixing the metal fine particles for the above-mentioned purpose, the weld line in this case does not protrude from the metal fine particles at the confluence of the molten material in the mold, which is applicable. A phenomenon in which a part appears dark in the appearance of a molded product. In order to prevent the occurrence of such weld lines, in addition to the above-mentioned molding conditions and product design, the size of the metal fine particles and the mixing ratio of the metal fine particles to the synthetic resin should be conditioned as in the above-mentioned conventional example. May be expected to have some effect. However, it lacks the elucidation of the decisive factor.

That is, the factors that the conventional example lacks are:
The structure or shape of the metal fine particles themselves. For example,
In the above-mentioned Japanese Patent Publication No. 4-27932, the corresponding portion is darkened because the metal fine particles do not exist at the place where the weld line is generated. However, this is a mistake in seeing the actual phenomenon of the generation of weld lines. Actually, the metal fine particles are also present at the confluence of the molten resin material, and it is confirmed by the present inventor that the corresponding place appears dark because the metal fine particles do not fall and stand up as described above. It is because it depends. In addition, in the conventional resin molded product, it is not limited to the confluence of the molten resin material as a whole, and depending on the viewing angle, etc., a dark pattern tends to appear in each part, and the brightness of the metal fine particles lacks brightness. There is.

Further, the conventional example has the following four problems. Looking at typical metal particles of aluminum, no matter how much the synthetic resin with which they are mixed is colored, the bare metal surface of the aluminum particles in the resin molded product only shows a shade. Even if the synthetic resin is transparent and clear, the silver white color of the aluminum particles and its luster only appear dispersed in appearance. That is, when aluminum fine particles are mixed with a synthetic resin containing a blue dye or pigment and molded, it is impossible to make the aluminum fine particles appear to shine red in the background blue color.

Although conventional metal fine particles have arbitrary shapes, they are actually crushed into irregular shapes. In this case, the fine metal particles are not evenly dispersed in the molten resin material in the mold. For example, small metal particles tend to gather together. Due to this, the collection of the metal fine particles may be deteriorated at the confluence of the molten resin material. In a resin molded product, it is intended to allow the viewer to recognize the glitter of the dispersed metal fine particles, but the difference in size and shape of the metal fine particles can be visually discerned as it is, which is not preferable in appearance. When mixed with a molten resin material, irregularly shaped metal fine particles are easily destroyed by heat and surface resistance, and the fragments lose neither coloration nor gloss, so that "dust" is scattered in the molded product. There is a visible disadvantage.

On the surface of the metal fine particles, the bare metal surface is exposed as it is and there is no kind of protective film. On the contrary, the oil component added at the time of manufacturing, stearic acid, oleic acid, naphtha, etc. remain on the surface, and the impact applied at the time of molding The active surface is exposed and oxidized by rubbing or rubbing, resulting in dull gloss and poor brightness. When metal fine particles having no protective film on the surface are mixed with a synthetic resin and molded, the impact resistance of the molded product (IZOT
The value) is inferior to that obtained by molding only the same synthetic resin. This is because the adhesion between the synthetic resin and the metal fine particles is poor. Therefore, there is a disadvantage that the purpose of use of the resin molded product is limited.

From this point of view, the object of the present invention is to obtain a resin molded product having an appearance like that of stars in the night sky, using metal fine particles per se which should be blended with a synthetic resin as a material. The purpose is to prevent the darkening phenomenon from occurring in each part of the resin molded product including the confluence of the molten resin material. Another object of the present invention is to obtain a synthetic resin composition which can secure the adhesion between the synthetic resin and the metal fine particles and improve the impact resistance of the resin molded product. Still another object of the present invention is to obtain a synthetic resin composition capable of developing metal fine particles in a resin molded product in a color different from the background color of the resin molded product.

[0010]

The present invention is a synthetic resin composition comprising a synthetic resin a and metal fine particles b such as aluminum blended as shown in FIG.
However, as shown in FIGS. 1 and 2, the outer peripheral surface 2 of the base foil 1 is
The heat-resistant colored coating film 5 is formed on both of the flat surfaces 3 and 4 except the above, and the flat surfaces 3 and 4 have substantially the same size and the same shape. The specific metal fine particles b may be circular or fan-shaped, but in consideration of yield and the like, they are the same quadrangle without an acute angle of 90 ° or more, and the notch 6 is provided at one corner. Make something. By forming a quadrangle having no acute angle portion of 90 ° or more, it is possible to well prevent the metal fine particles b from protruding during molding. As a concrete example of the rectangular shape, a quadrangle or a hexagon can be considered. As the base foil 1, a general-purpose aluminum foil having a thickness of 6 to 60 μm is preferable in view of mass productivity and the like, but copper, stainless steel, brass or the like may be used separately.

The synthetic resin a to which the metal fine particles b are mixed is
It widely includes polystyrene, acrylic resin, polyethylene, etc., but is desired to have a certain degree of transparency. The synthetic resin a is preferably of the same series as the synthetic resin material of the colored coating film 5 in order to secure the strength by adhering to the fine metal particles b.

The metal fine particles b of the present invention are formed by applying a colored coating film on the front and back surfaces of the extended base foil material, and then punching and cutting the base foil material into the same size and the same shape with a die cutting machine. The particle size, that is, the size of one side is 25 μm
Approximately 5 mm. On the metal fine particles b, the colored coating film 5
Serves as a protective film on both flat surfaces 3 and 4 of the base foil 1 and also contributes to the adhesion to the synthetic resin a. As the pigment 7 in the colored coating film 5, a material obtained by previously crushing the raw material into a scaly shape is used. That is, it is preferable that the pigment 7 has elasticity and transparency so as not to be crushed when crushed, and a representative example thereof is melamine cyanurate, and the mixing amount in the colored coating film 5 is 1 to 10 weight. % Is preferred.

The colored coating film 5 is a paint having good transparency and reflection brightness, and is formed to have a thickness of 0.1 to 3.0 μm. Specifically, for example, polystyrene, ABS resin, polyethylene, or the like, which may be formed by including the pigment 7 in a heat-resistant thermoplastic synthetic resin-based paint capable of withstanding the cylinder temperature and the mold temperature, It is also possible to use a baked coating of a thermosetting synthetic resin type paint, for example, an acrylic resin type paint. The heat resistance here is sufficient if it does not melt.

Adhering the metal fine particles b to the synthetic resin a without interposing bubbles helps improve the impact resistance of the synthetic resin molded product. For this purpose, the metal fine particles b are soaked in a liquid such as silicone oil in advance, mixed and stirred, and sufficiently moistened with the liquid to remove air from the surface of the metal fine particles b. Compound. The liquid for that purpose may be a volatile liquid and is not particularly limited.

[0015]

Since the metal fine particles b have the same size and the same shape, when the molten resin material flows in the cylinder and the mold,
The metal fine particles b are molded in a state in which they are uniformly dispersed. Even in the portion where the molten resin material merges, the fine metal particles are well and uniformly dispersed. The notch 6 provided in the metal fine particle b acts so as to break the weight balance of the metal fine particle b itself and disperse the metal fine particle b more uniformly. Then, when the flow of the molten resin material stops in the mold, each metal fine particle b of the same size and the same shape
Are less entangled with each other as compared with the irregular hook shape, and the weight balance is lost in the cutouts 6, and the flats easily fall down. Similarly, at the place where the original weld line is likely to occur, the metal fine particles b also fall flat.

The colored coating film 5 functions as a protective film for the base foil 1, and even when mixed in the colorless and transparent synthetic resin a, the colored coating film 5 allows various colors to appear in the resin molded product. it can. Further, by mixing and using a plurality of kinds of metal fine particles b having different colors of the colored coating film 5, it is possible to express a deep metallic feeling and also to maintain the transparency of the synthetic resin. On the other hand, when the metal fine particles b are mixed with the synthetic resin a colored with a dye or a pigment, the color of the colored coating film 5 of the metal fine particles b can be made different from the background color of the synthetic resin a. For example, when metal fine particles b having a yellow colored coating film 5 are mixed with blue synthetic resin a and molded, in the resin molded product, the scattered metal fine particles b develop green, and the white synthetic resin a If the colored coating film 5 is blended with the black fine metal particles b, it will have an appearance like marble.

In the resin molded product obtained by the synthetic resin composition of the present invention, by looking at the colored coating film 5 on the flat surfaces 3 and 4 of each metal fine particle b, this reveals the glittering like stars scattered in the night sky. Put out. At this time, a pigment 7 is included in the colored coating film 5 of each metal fine particle, and as the pigment 7, melamine cyanurate having transparency is used. The raw material of melamine cyanurate is basically available as a dry powder having a spherical shape of 2 to 3 μm, but if this kind of pigment 7 remains spherical, when a resin molded product is viewed, it may be angled, for example, in an oblique direction. , The pigment 7 itself does not reflect light in all azimuth directions, and a dark portion appears in a part, which tends to cause darkening. In this respect, if the pigment 7 is previously crushed into a scaly shape, it reflects light in all azimuth directions, and as a result, in the synthetic resin molded product, the metal fine particles b are bright without darkening when viewed from any angle. Sparkle.

When the metal fine particles b are blended with the synthetic resin a as they are, the metal fine particles b are formed in the cylinder and the mold during molding.
The air on the surface of is heated to form bubbles, and a part of the bubbles adheres to the surface of the metal fine particles b, thereby making the brightness dull,
The rest of the bubbles go out and form fine pinholes on the outer surface of the resin molded product. At the same time, in the resin molded product, the adhesion between the synthetic resin component and the fine metal particles b deteriorates, which reduces the impact resistance of the resin molded product. In order to prevent this, the outer surface of the metal fine particles b is previously wetted with a liquid such as silicone oil to remove air, and then the metal fine particles b are blended with the synthetic resin a made into pellets or powders. If the material is injected into the mold together with the cylinder, it is possible to suppress the above-mentioned generation of bubbles.

[0019]

EFFECT OF THE INVENTION According to the synthetic resin composition of the present invention, a resin molded product in which the metal fine particles b are uniformly dispersed without observing the occurrence of dark weld lines and a glittering star-like product in the night sky is obtained. Obtainable. When the synthetic resin a and the colored coating film 5 of the metal fine particles b are the same series of synthetic resin materials, the outer surfaces of the metal fine particles b are covered with a liquid such as silicone oil to remove air, and then the metal fine particles b are removed.
When is mixed with the synthetic resin a, the adhesion of the metal fine particles b to the synthetic resin a is improved, so that the impact resistance of the resin molded product can be improved. By selecting the color of the colored coating film 5 arbitrarily, it is possible to obtain a resin molded product having various glitter.

[0020]

[Example] A paint containing 5% by weight of a pigment (melamine cyanurate) mixed with polystyrene resin was applied on both the front and back smooth surfaces of an aluminum foil spread to a thickness of 30 μm to a thickness of 0.1.
After forming a colored coating film having a thickness of μm, it was precisely punched and cut into the same shape and the same size by a die-cutting machine to form rectangular flat aluminum fine particles (fine metal particles) shown in FIG. That is, as shown in FIGS. 1 and 2, the aluminum fine particles are made of an aluminum foil having a thickness of 30 μm as a base foil 1, and an outer peripheral edge 2 of the aluminum foil is left as a bare metal surface, and both flat surfaces 3 and 4 of the base foil 1 are used.
1.0 μm thick colored coating films 5 and 5 are formed on each side, and all have substantially the same rectangular shape at the time of punching and cutting, and the particle size on the long side is 1.0 mm. And a round notch 6 was formed at one corner.

Melamine cyanurate was used as the pigment 7 contained in the colored coating film 5. This melamine cyanurate is obtained as a dry powder that has a spherical shape of substantially 2.0 to 3.0 μm in the raw material, and is preliminarily rolled on a roller to have a thickness of about 1.0 μm and a diameter of about 6 μm which is substantially circular. Was crushed into scales and mixed in the paint forming the colored coating film 5.

(Example 1) In FIG. 3, 94.5 parts by weight of a transparent polystyrene resin as a synthetic resin a, 0.5 parts by weight of the aluminum fine particles having a black colored coating film 5 as metal fine particles b, and titanium oxide 2 0.0 parts by weight, silicone oil 3.0
A cosmetic container (compact) was injection-molded with a mold using a synthetic resin composition containing parts by weight. That is, first, aluminum fine particles and silicon oil are mixed and stirred to wet the surface of the aluminum fine particles with silicon oil, and then the aluminum fine particles containing silicon oil, the pelletized polystyrene resin and the titanium oxide are mixed, and thus obtained. Injection molding was performed using the obtained synthetic resin composition. In this case, the resin molded product was titanium oxide and had a white background color, and black aluminum fine particles were uniformly distributed therein, and had an excellent appearance reminiscent of marble. When the appearance was closely observed, the outer surface was finished to be a neat smooth surface without fine pinholes generated by the escape of bubbles during molding. No air bubbles were observed on the surface of each aluminum particle. This is because silicon oil has been removed beforehand so that air bubbles do not adhere to the surface of the aluminum fine particles. Then, the aluminum fine particles were uniformly dispersed throughout the entire area including the portion where the molten resin material merges in the mold, and no weld line was observed that appeared dark. In other words, the aluminum fine particles uniformly dispersed throughout the whole fell well on average without protruding, and had a good appearance in which black dots were bright and shimmering when viewed from any angle.

(Example 2) 97.5 parts by weight of a transparent polystyrene resin as a synthetic resin a, 0.5 parts by weight of the aluminum fine particles having a black colored coating film 5 as the metal fine particles b, and 2.0 parts by weight of titanium oxide. The synthetic resin composition containing was granulated into spherical pellets, and a cosmetic container (compact) was injection-molded with the pellets. That is, the addition of silicone oil in Example 1 was eliminated. In this resin molded product as well, pinholes due to the escape of bubbles during molding were observed on the outer surface under a microscope, but the same good marble pattern as in Example 1 was revealed.

Example 3 Transparent AB as synthetic resin a
A synthetic resin composition containing 98.5 parts by weight of the S resin and 1.5 parts by weight of the aluminum fine particles as the metal fine particles b was prepared.
Was injection molded. However, as the colored coating films 5 and 5 on both flat surfaces 3 and 4 of the aluminum fine particles, ones made of an ABS resin paint were used, one of which was red and the other of which was white, which were changed from the front to the back. As a result, a brilliant and novel resin molded product in which red and white were evenly and alternately scattered was obtained.

(Embodiment 4) 81.3 parts by weight of a transparent acrylic resin as a synthetic resin a and a colored coating film 5 as a metal fine particle b.
A synthetic resin composition containing 15 parts by weight of silver-colored aluminum fine particles and 4.7 parts by weight of a blue dye was prepared, and a cosmetic container (compact) was injection-molded in the same manner as in Example 2. In this resin molded product, a deep blue (navy blue color close to black) ground color appears, and glittering aluminum fine particles are uniformly distributed in the ground color, and the appearance has a high-class feeling and is excellent.

The same cosmetic container (compact) was injection-molded with polystyrene resin only without any fine metal particles and the like, and the impact resistance of the resin molded product obtained by this comparative example and the above-mentioned Examples 1 and 2 ( Looking at the IZOT value),
The comparative example is 9.5, the first embodiment is 9.4, and the second embodiment is 9.0.
Met. Therefore, if the surface of the metal fine particles is previously covered with a liquid such as silicone oil, the generation of bubbles during molding can be well suppressed, and the metal fine particles and the synthetic resin will adhere well to each other, which will improve the strength (resistance It was confirmed that the impact resistance) increased.

[Brief description of the drawings]

FIG. 1 is a perspective view of metal fine particles.

FIG. 2 is a cross-sectional view of metal fine particles.

FIG. 3 is a cross-sectional view of a synthetic resin composition.

[Explanation of symbols]

 a synthetic resin b metal fine particles 1 base foil 2 outer peripheral surface 3.4 flat surface 5 colored coating film 6 notch 7 pigment

Claims (3)

(57) [Claims] 1. A synthetic resin composition comprising a synthetic resin a and metal fine particles b, wherein the metal fine particles b are heat-resistant colored coating film on both flat surfaces 3 and 4 of the base foil 1 excluding the outer peripheral surface 2. 5 are formed and are set to have substantially the same size and the same shape, and the colored coating film 5 is a spherical melamine cyanuree which is a raw material.
Made of synthetic resin paint containing Pigment 7
The outer surface of synthetic resin a is covered with a liquid such as silicone oil.
The separated metal fine particles b are distributed in a proportion of 0.01 to 50% by weight.
A synthetic resin composition which is characterized by being mixed. 2. The fine metal particles b are made of aluminum having a size of 6 to 60 μm.
The synthetic resin composition according to claim 1 , which is a aluminum foil, is a quadrangle having no acute angle portion of 90 ° or more , and is provided with a notch 6 at one corner portion. 3. Pigment 7 is contained in colored coating film 1 in an amount of 1 to 10% by weight.
The synthetic resin composition according to claim 1, which is mixed .