JP2000159926A - Aluminum flake for kneading with resin and molding product of resin - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain the subject flake having excellent brilliance, clarity, feeling of high class, feeling of uniformity and feeling of denseness free from a defective appearance caused by weld-mark, having a specific particle diameter, comprising a small amount of particles having a specific particle diameter or larger than it, having an average thickness in a specified range. SOLUTION: This flake has 2-8 μm average particle diameter by a laser diffraction method, comprises <=5 wt.% of particles having >=10 μm particle diameter and has 0.1-0.6 μm average thickness and preferably >=2.1 gradient n of line when the particle size distribution is shown by a Rosin-Rammler diagram. The flake preferably in an amount of 0.005-5 pts.wt. is added to 100 pts.wt. of a resin to give a molding product of resin. Preferably reflectance L value (d=0) of the molding product of the resin is >=60.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a novel aluminum flake for resin kneading and a resin molding.

[0002]

2. Description of the Related Art Conventionally, metal particles such as aluminum pigments have been blended to give a glossy appearance to a resin molded product. These resin molded products can be roughly classified into two types according to the particle shape of the metal particles mixed therein.

[0003] The first is a resin molded article containing general particles. For example, by filling metal particles of fine powder or ultrafine powder into a resin, a molded article having a uniform metal tone (that is, metallic tone) over the entire surface (Japanese Patent Laid-Open No.
8-37045) and the like. However,
In this molded product, a weld mark may be significantly generated. In other words, when this molded product is manufactured by injection molding, a layer containing no metal particles is formed at the tip of the molten resin in the mold, so that a weld mark composed of only the resin is formed at a portion where the flows merge. You. Since this weld mark does not contain metal particles, it absorbs light and looks like a blackish color, which significantly impairs the appearance.

[0004] The second is a resin molded article containing particles having a specific shape. For example, a molded product in which a metal flake powder having an average equivalent diameter of 30 μm or more and an average shape ratio of 1/10 or less is mixed with a resin (JP-A-5-93091) is known. However, in this molded article, the metal flake powder is broken by receiving a shearing force during the step of kneading the resin and the metal flake powder and the molding step. When the metal flakes are broken, weld marks are significantly generated as in the case of the first compact. Further, even if the metal flakes are not broken, relatively coarse particles are mixed, so that there is a possibility that the appearance is not uniform and calm and cheap.

[0005]

In recent years, in order to solve these problems, there has been proposed a method of using glossy particles having an average equivalent diameter of 30 μm or more and an average shape ratio of 1/8 to 1/1. (Japanese Patent Publication No. 6-99593).

[0006] However, in the above-mentioned technology, 1) the glitter must be sacrificed because relatively large particles are used, and 2) a relatively large amount of particles must be blended to give a high-quality metallic tone. Must not, 3)
There are problems such as insufficient prevention of weld marks.

When large particles are used, the surface roughness of the resin molded article tends to increase accordingly, and in extreme cases, the particles protrude or peel off from the surface of the molded article. These protrusions or protrusions are fatal defects when the resin molded body is used for a body of a precision small device such as a mobile phone, a portable personal computer, and an electronic organizer.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to solve these problems of the prior art, and it is a main object of the present invention to provide a resin molded article which is free from poor appearance due to weld marks and has excellent glitter and sharpness. I do.

[0009]

Means for Solving the Problems The present inventor has conducted intensive studies in order to solve the problems in the prior art, and as a result, by blending aluminum flakes whose particle size is controlled in a specific range into a resin, the above object has been achieved. Have been achieved, and the present invention has been completed.

That is, the present invention relates to the following aluminum flakes for resin kneading and resin moldings.

1. Average particle size of 2 by laser diffraction method
Aluminum flakes for resin kneading having a particle size of 8 μm, particles of 10 μm or more, 5% by weight or less, and an average thickness of 0.1 to 0.6 μm.

2. 2. A resin molded article containing the aluminum flake according to the above item 1.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION The aluminum flake of the present invention has an average particle size of usually about 2 to 8 μm, particularly preferably 3 to 7 μm, as described above. When the average particle size is less than 2 μm, it becomes difficult for each particle to be recognized, and at the same time, the particles themselves may become dark and the glitter may decrease. Also, when the average particle size is more than 8 μm, the brilliancy is reduced and the sharpness may be impaired.

In the present invention, particles having a size of 10 μm or more must be 5% by weight or less. When the particles having a particle size of 10 μm or more exceed 5% by weight, the uniformity and the denseness are lost, and the large particles are remarkably glaring and lose the sense of quality.

The average thickness is usually about 0.1 to 0.6 μm, but preferably 0.1 to 0.4 μm. When the average thickness is less than 0.1 μm, a weld mark may be significantly generated. On the other hand, when the average thickness exceeds 0.6 μm, the aspect ratio of the particles becomes small, so that the glitter and the sharpness are reduced.

The aluminum flake of the present invention further comprises:
In the case where the particle size distribution is represented by a Rosin-Rammler particle size diagram, the linear gradient n (equivalent number) is usually preferably 2.1 or more, and more preferably 2.2 to 2.6. When the above value is less than 2.1, a weld mark is easily generated in the resin molded body,
In addition, there is a possibility that a satisfactory sense of quality and uniformity may not be obtained.

The aluminum purity of the aluminum flake of the present invention is not particularly limited, and other metals may be contained as impurities or alloy components as long as the effects of the present invention are not impaired. Examples of the impurities or alloy components include Si, Fe, Cu, Mn, Mg, and Zn.

The method for producing aluminum flakes of the present invention is not particularly limited as long as the above-mentioned predetermined particle size control can be performed.
It can also be produced according to a known method for producing aluminum flakes. For example, it can be obtained by subjecting atomized powder, aluminum foil, vapor-deposited aluminum foil and the like to pulverization, grinding and the like by a ball mill, an attritor, a vibration mill, a stamp mill or the like. In particular, the aluminum flakes of the present invention can be suitably produced by grinding fine aluminum powder (average particle size of about 1 to 6 μm) obtained by the atomizing method with a ball mill.

The aluminum flake of the present invention can be suitably used for mixing resin. That is,
In the resin molded article of the present invention, the above-mentioned aluminum flakes can be suitably used.

The resin that can be applied is not particularly limited, and resins used in conventional resin moldings can also be used. Examples include polyethylene, polypropylene, chlorinated polyethylene, ethylene-vinyl acetate copolymer, polyvinyl chloride, polystyrene, acrylic resin, polycarbonate, polyamide, polyimide, ABS resin, and AS resin. These can be used alone or in combination of two or more.

The amount of the aluminum flake is usually about 0.005 to 5 parts by weight per 100 parts by weight of the resin.
Preferably, it may be 0.01 to 2 parts by weight. 0.00
If the amount is less than 5 parts by weight, the metallic feeling generally tends to be poor. If the amount exceeds 5 parts by weight, unevenness may occur or the cost may increase. However, depending on the properties of the flakes used, the type of resin, the use of the final product, and the like, there may be cases where the amount may be outside the above range.

In the resin molded article of the present invention, in addition to the above aluminum flakes, if necessary, a coloring agent (pigment / dye), a stabilizer, a dispersant, a weathering agent, an antistatic agent, a viscosity modifier, a release agent, Known additives such as a foaming agent and a flame retardant can also be appropriately compounded.

The reflectance L value (d = 0) of the resin molded article of the present invention is preferably 60 or more, particularly preferably 65 or more. The resin molded product having such an L value is particularly excellent in brilliancy and metallic feeling, exhibits a novel appearance which is not present in conventional resin molded products, and can exert an excellent effect in that the product is more conspicuous. .

The resin molded article of the present invention can be produced in the same manner as a known resin molded article. For example, a resin molded body can be obtained by uniformly kneading the resin, the aluminum flakes, and other additives, and then molding. The molding method is not particularly limited, for example, an injection molding method,
Known molding methods such as an extrusion molding method, a calendar molding method, and a blow molding method can be employed.

[0025]

The aluminum flakes of the present invention can exhibit an excellent effect for mixing resin because the particle size is controlled within a certain range.

That is, the resin molded article of the present invention containing such aluminum flakes has no appearance defect due to the weld mark (ie, the occurrence of the weld mark is suppressed to such an extent that it cannot be recognized by the naked eye, or the commercial value is not reduced. Is suppressed.)
In addition, the resin molded article of the present invention is excellent in brilliancy and sharpness, and has a sense of quality, uniformity and denseness.

In particular, since no large particles are used,
The surface roughness is small and smooth, and there is no risk that particles protrude or come off from the surface. From this point as well, it can contribute to the improvement of the sense of quality and uniformity.

The resin molded article of the present invention having the above-mentioned characteristics is used for optical equipment such as cameras and video cameras, audio equipment such as radio-cassettes and CD players, OA equipment such as personal computers, displays and printers, automobiles, motorcycles and the like. Interior and exterior goods, televisions, vacuum cleaners, refrigerators and other home appliances,
In addition, it can be suitably used for various molded articles such as sports goods and cosmetics (containers).

[0029]

Next, the features of the present invention will be specifically described with reference to examples and comparative examples.

Examples 1 to 7 and Comparative Examples 1 to 3 Aluminum flakes having the properties shown in Table 1 were used, kneaded at 230 ° C. with the ABS resin in the composition shown in Table 1, and injection-molded at the same temperature. A resin molded body having the shape and dimensions (thickness t = 2.5 mm) shown in FIG. In addition, in each molded body, titanium oxide was uniformly added as a coloring pigment in an amount of 0.2.
% By weight. The appearance and the like of each obtained molded body were observed. Table 1 shows the results. Each physical property in Table 1 was measured and evaluated by the following methods.

(1) Average Particle Size and Ratio of Particles of 10 μm or More Measured by a laser diffraction method. That is, it was measured by a laser diffraction type particle size distribution analyzer (“SALD-1100” manufactured by Shimadzu Corporation).

(2) Average Thickness The cross section of each compact was observed with a scanning electron microscope, and the thicknesses of 20 randomly selected particles were arithmetically averaged.

(3) Equal number (= linear gradient n) The linear gradient n was determined from a Rosin-Rammler particle size diagram. The Rosin-Rammler particle size diagram is given by the formula R = 100exp
FIG. 3 shows a particle size diagram showing a particle size distribution according to (−bD ⁿ ) ( ^where R is the cumulative weight% from the maximum particle size to the particle size D, D is the particle size, and b and n are constants). The gradient n corresponds to the n value of the above equation approximated by a straight line connecting the cumulative weight% from the vicinity of the maximum particle size to the particle size D in the particle size diagram.

(4) L value (reflectance) Measured according to JIS K5400 (incident angle 60 °, light receiving angle 0 °).

(5) Alcove laser type metallic feeling measuring device (“LMR-100”)
(Kansai Paint).

IV value : From the signal iv at the light receiving angle at which the maximum intensity is obtained excluding the light in the specular reflection area reflected on the clear layer surface out of the laser reflected light irradiated at an incident angle of 45 degrees, the equation IV = K1 × iv (K1 is a coefficient) is obtained by calculating the intensity (luminance,
(Brightness). Note that I
The V value can also be a guide for knowing the glitter in the present invention.

SV value : SV obtained by the equation SV = K2 × sv (K2 is a coefficient) from the signal sv at the light receiving angle at which the light intensity becomes the minimum in the specular reflection region of the laser reflected light irradiated at an incident angle of 45 degrees. The value was used as a parameter proportional to the intensity (whiteness / light scattering) of diffusely reflected light from aluminum flakes. This value correlates with a color called "watermark color" or "flop color".

FF value : This value is obtained by making the degree of change in reflected light intensity when the observation angle (light receiving angle) changes, non-dimensional by the average reflection intensity, and is expressed by the formula: FF = K3 × (iv−s)
v) / (iv + sv) (K3 is a coefficient), and the blending degree (directionality,
(Inclination distribution of flakes). Note that the FF value can also be a guide for knowing the sharpness in the present invention.

(6) Weld mark The surface condition of the molded product was visually observed. ○ indicates that the occurrence of the weld mark is not recognizable to the naked eye or has no appearance defect due to the weld mark, Δ indicates that the occurrence of the weld mark is easily recognizable, x indicates that the weld mark is conspicuous and has no commercial value. evaluated.

(7) Sharpness The surface of the molded product was visually observed.は was evaluated as excellent or good, △ as normal (same as the conventional product), and × as poor.

(8) High quality The surface of the molded product was visually observed. ○: No cheapness of plastic alone, excellent in metallic feeling and flip-flop feeling, and no roughness was observed. △: Average (same as conventional products), ×: Cheap impression, and roughness was recognized. , And evaluated.

(9) Uniformity The surface of the molded product was visually observed. ○ indicates that the particles are uniformly dispersed and the surface is smooth, Δ indicates average (same as the conventional product), and × indicates the presence of foreign matter mixed in, and some glare is observed, and lacks uniformity. The thing was evaluated.

[0043]

[Table 1]

From the results in Table 1, it is found that Examples 1 to 5 according to the present invention were used.
It can be seen that the resin molded product of No. 7 exerts an excellent effect on any of the physical properties.

[Brief description of the drawings]

FIG. 1 is a view showing shapes and dimensions (unit: mm) of molded articles produced in Examples and Comparative Examples. In addition, 20 in FIG.
A rectangular part of mm × 20 mm is hollow.

 ──────────────────────────────────────────────────続 き Continued on the front page F-term (reference) 4J002 BB031 BB061 BB121 BB241 BC031 BC061 BD041 BG031 BN151 CG001 CL001 CM041 DA096 FA016 FD030 FD080 FD090 FD100 FD130 FD160 FD200 FD206 FD320 FD330 GC00 00GG01GN00

Claims (5)

[Claims] An average particle size of 2 to 8 μm by a laser diffraction method.
m, and 5% by weight or less of particles of 10 μm or more and an average thickness of 0.1 to 0.6 μm. 2. The aluminum flake for kneading resin according to claim 1, wherein the linear gradient n is 2.1 or more when the particle size distribution is represented by a rosin-Rammler particle size diagram. 3. A resin molded article containing the aluminum flake according to claim 1. 4. The method according to claim 1, wherein the resin is 100 parts by weight.
A resin molded article containing 0.005 to 5 parts by weight of aluminum flake according to 1. 5. The resin molded product according to claim 3, wherein the reflectance L value (d = 0) is 60 or more.