JPH02170847A - Granite-like acryl resin molded article - Google Patents

Abstract

PURPOSE:To obtain a beautiful granite-like acryl resin molded article having high productivity and good mechanical strength by blending a specific amount of white based inorganic pigment and aluminum foil powder with a methyl methacrylate polymer and subjecting the blend to injection molding. CONSTITUTION:The aimed molded article obtained by blending (A) 100 pts.wt. (co)polymer containing >=80% methyl methacrylate and having 50000-500000, preferably 70000-300000 molecular weight with (B) 0.1-3 pts.wt., preferably 0.5-2 pts.wt. white based inorganic pigment (e.g. titanium oxide or barium sulfate) and (C) 0.1-1.5 pts.wt., preferably 0.2-1 pts.wt. aluminum foil powder being 1-50mum, preferably 6-20mum in thickness of foil, 0.03-0.8mm, preferably 0.05-0.5mm in size of side and 50-250mum, preferably 60-200mum in weight-average particle size and subjecting the blend to injection molding and having <=10%, preferably <=5% total light transmittance.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an acrylic resin molded article having a granite texture.

[Conventional technology]

Conventionally, in order to add speckled patterns to acrylic resin molded products to create a granite-like shade, it is necessary to use rocks that are colored black or other colors.
A method of incorporating pulverized particles of glass, ceramics, etc., inorganic fiber microfillers such as colored glass (Unexamined Japanese Patent Publication No. 1983-1982)
86729), or a method of making a black-colored molded product with the same composition as the plastic molded product and incorporating crushed particles thereof (such as JP-A-62-197346).

(Problems to be Solved by the Invention) However, since the conventional method is mainly applied by a casting method, productivity is low and costs are inevitably high. There is a problem that there is a large difference in specific gravity between the resin and the inorganic filler, which tends to cause defects such as uneven dispersion, or when using a colored resin pulverized product, it is difficult to obtain the solid feeling of an inorganic material like granite. Ta.

Therefore, in order to solve the above-mentioned problems, the present invention provides a beautiful brown-grained acrylic resin molded product having high productivity and good mechanical strength, which is made by injection molding a resin containing an inorganic pigment and an inorganic filler. The purpose is to obtain.

[Means for solving problems]

As a result of intensive study to solve the above problems, the present inventors found that
It was discovered that by injection molding an acrylic resin blended with a white inorganic pigment and aluminum foil powder so as to have a low total light transmittance, a granite-like acrylic resin molded product that satisfies the above objectives could be obtained, and the present invention was developed. completed.

According to the present invention, the above object is achieved by injection molding by blending 0.1 to 3 parts by weight of a white inorganic pigment and 0.1 to 1.5 parts by weight of aluminum foil powder to 100 parts by weight of a methyl methacrylate polymer. This is achieved using a mauve-like acrylic resin molded product with a total light vA transmittance of 10% or less.

The methyl methacrylate polymer used in the present invention refers to a copolymer or homopolymer containing 80% or more of methyl methacrylate, and includes ultraviolet absorbers, heat stabilizers, colorants,
There is no problem in containing additives such as fillers. Further, the molecular weight is not particularly limited in the present invention, but is generally from 50,000 to 500,000, preferably from 70,000 to 300,000, from the viewpoint of ease of kneading during injection molding or physical properties. .

As the white inorganic pigment used in the present invention, those normally used as bone white pigments and milky white pigments can be used, such as titanium oxide, barium sulfate, and the like. The amount added is 0 to 100 parts by weight of methyl methacrylate.
．． The amount is 1 to 3 parts by weight, preferably 0.5 to 2 parts by weight.

If the amount of the white inorganic pigment added is less than 0.1 parts by weight, it will become transparent and the total light VA transmittance will increase, which is undesirable.On the other hand, if the amount added exceeds 3 parts by weight, the molded product Physical properties such as mechanical strength tend to deteriorate, which is undesirable.

Further, the aluminum foil powder used in the present invention has a thickness of 1 to 50 pm, preferably 6 to 2011 m.
- It refers to a crane with a side size of 0.03 to 0.8 mm, preferably a square with a side size of 0.05 to 0.5 mm, or a polygon shape of an equivalent size cut or punched. It is also possible to use a mixture of foil powder bundles of different sizes, and it is also possible to mix and use a small amount of foil powder bundles larger than the above-mentioned size in order to better reproduce the shadow tone of rocks. If we were to express the size of these aluminum foil powders in terms of particle diameter, it would be measured by the gravimetric sedimentation method ((
Seishin Enterprise Co., Ltd. Transmission 2 particle size distribution analyzer SKA 5
000) L, weight average particle diameter is 50-250 μm1
Preferably it is 60 to 200 μm.

If the size of the foil powder bundle exceeds 0.81, the unevenness on the surface of the molded product will become large, which is undesirable.
If it is less than 3n, the tendency for a granite tone will become faint, which is not preferable. The blending amount varies depending on the intended use, but in order to obtain a beautiful granite-like molded product, the blending amount is 0.1 to 1.5 parts by weight per 10 g of methyl methacrylate polymer.
Parts by weight, preferably 0.2 to 1.0 parts by weight. If the amount is less than 0.1 parts by weight, a granite-like texture will not be produced, while if it exceeds 1.5 parts by weight, unevenness will occur on the surface and the appearance of the molded product will be easily damaged. In addition, there is no economic advantage and it is not desirable. The aluminum foil powder of the present invention can be coated with a modified acrylic resin on the foil surface for the purpose of not reducing the mechanical strength of the molded product or for the purpose of coloring, thereby further improving chemical resistance and gloss. Improvements can be made.

The shade-like acrylic resin molded product of the present invention is produced as described above (
, is made by blending 0.3 to 3 parts by weight of a white inorganic pigment and 0.1 to 1.5 parts by weight of aluminum foil powder to 100 parts by weight of methyl methacrylate polymer. Since the surface is uneven, it is necessary to injection mold it from the viewpoint of surface gloss or beauty. To give an example of a manufacturing method, for example, the above-mentioned methyl methacrylate polymer, aluminum foil powder, and inorganic pigment are stirred and mixed using a Henschel mixer, or after stirring and mixing, the mixture is formed into a pellet by an extrusion molding machine, etc. A molded product is obtained by injection molding. The injection molding conditions in the present invention are not essential constituent conditions of the present invention, and by injection molding using a normal injection molding machine and under normal injection conditions, an acrylic resin molded product with a granite finish can be obtained. .

Further, it is desirable that the shaded acrylic resin molded article of the present invention produced as described above has a total light transmittance of 10% or less, preferably 5% or less. Total light transmittance is 1
If it exceeds 0%, the amount of light transmitted increases, so that the aluminum foil powder shines and a speckled pattern texture such as a granite-like black color cannot be obtained. This point is one of the major points of the present invention, and the synergistic effect with the concealing effect of the white pigment creates a shaded look that cannot be obtained with aluminum foil alone.

〔Example〕

Hereinafter, the present invention will be explained in more detail with reference to Examples.

Note that all "parts" in Examples and Comparative Examples refer to "parts by weight," and the performance of the acrylic resin molded products obtained in Examples and Comparative Examples was measured and evaluated by the following method.

Surface conditions The conditions visually observed by reflecting a fluorescent light onto the sample in the chamber are shown below using symbols.

○...Beautiful granite tone is recognized △...Beautiful granite tone, but fine irregularities are observed ×・
...It has a granite tone, but the surface has many irregularities and lacks beauty. Light transmittance measurement Integrating sphere type light transmittance measuring device (Murakami Color Research Institute: Light transmittance/reflectance) in accordance with JIS 7105 Total RM-5)
The total light transmittance and parallel light transmittance were calculated.

Surface Roughness The ten-point average roughness (Rz) was measured using a surface roughness meter (Koita Institute Co., Ltd.: Universal Surface Profile Measuring Instrument 5E-3C) in accordance with JISBO601.

Whiteness was measured using SM Power Computer: 5M-2 manufactured by Suga Test Instruments.

Mechanical strength AST? Tensile strength (Shimadzu Autograph Model 055-5000) was measured in accordance with 1D638 and AS
It was measured by Izotsu impact strength (Toyo Seiki Izotsu impact tester) in accordance with TMD256.

Example 1 Contains 12% methyl acrylate and has a molecular weight of 120.00
Aluminum foil powder (thickness 12 μm, size 0.05×0
．． 08n weight average particle size 70 μl) 0.4 parts, 1.0
After adding 1.0 parts of 0.3μ titanium oxide to each part and 2.0 parts and stirring and mixing with a Henschel mixer, each mixture was pelletized with an extruder and molded with an injection molding machine, and the thickness was A flat plate molded product of 2 dragons was obtained. Table 1 shows the performance evaluation results of these molded products. A molded product with a beautiful magenta finish was obtained.

Example 2, Comparative Example 1 Aluminum foil powder of different sizes (thickness 12
μm1 size 0. I X O, 14 dragon weight average particle diameter 95 μm; thickness 12 μm, size 0, 2 X O,
Weight average particle diameter 140μm at 28m; thickness 12μ silk;
Size 0.4 x O, weight average particle diameter 185μ at 5m
l; Thickness 12μ11 Size 0.9 x 1.0 Tsuru weight average particle diameter 260μm) 0.4 parts added, and 0.3μ
1.0 part of titanium oxide was added to each, mixed and stirred with a Henschel mixer, pelletized with an extruder, and injection molded in the same manner as in Example 1 to obtain a flat plate with a thickness of 2 fl.Performance evaluation of these molded products. The results are also shown in Table 1. A molded product with a beautiful granite finish and a surface with many irregularities was obtained.

Comparative Example 2 1.0 part of 0.3 μm titanium oxide was added to 100 parts of the same methyl methacrylate polymer as in Example 1, mixed and stirred with a Henschel mixer, and then pelletized with an extruder.
Injection molding was performed in the same manner as in Example 1 to obtain a flat plate molded product with a thickness of 2 fl. The performance evaluation results of this molded product are shown in Table 1, and the mechanical strength was almost the same as that of the molded product of Example 1.

Comparative Example 3 To 100 parts of the same methyl methacrylate polymer as in Example 1, 1.0 part of 0.3μ titanium oxide and 0.4 part of black colored glass fiber powder were added, and the mixture was mixed with a Henshil mixer. When the mixture was mixed and stirred, the metal wall of the mixer was worn away by the glass fiber powder, so molding was abandoned because it was thought that the mold and molding machine would be worn out.

Comparative Example 4 1.0 parts of calcium carbonate and a weight average particle diameter of 7 were added to 100 parts of the same methyl methacrylate polymer as in the example.
1.6 parts of 0 μN aluminum foil powder was added, mixed and stirred with a Henshil mixer, pelletized with an extruder, and injection molded in the same manner as in Example 1 to obtain a flat plate molded product with a thickness of 21 mm. The performance evaluation results of this molded product are shown in Table 1, and the total light transmittance of this molded product was high, and the aluminum foil powder, which did not exhibit any granite tone, was in a shining state.

〔Effect of the invention〕

As explained above, in the present invention, 0.1 to 3 parts by weight of a white inorganic pigment and 0.1 to 1.5 parts by weight of aluminum foil powder are blended to 100 parts by weight of a methyl methacrylate polymer, and the mixture is injection molded. Since it is an acrylic resin acid shaped product with a total light transmittance of 10% or less, it can be injection molded without damaging the mold, and it does not reduce mechanical strength, allowing for high production. It is possible to provide a beautiful magenta-like acrylic resin molded product having good durability and mechanical strength at a low cost, and it is useful for uses such as sculptures, bathroom utensils, and miscellaneous goods.

Claims (1)

[Claims] 100 parts by weight of methyl methacrylate polymer, 0.1 to 3 parts by weight of white inorganic pigment and 0.1 to 1.5 parts by weight of aluminum foil powder are blended and injection molded, and the total light transmittance is 10. % or less.