JPS6212248B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to an improved method for producing polyolefin resin molded articles. Generally, when molding polyolefin resin, an organic reinforcing agent such as wood flour is added along with a coloring agent for the resin to improve the physical properties, but during the molding process, the organic reinforcing agent has a low affinity with polypropylene and is not colored. Therefore, if a scratch occurs on the molded product, the uncolored organic reinforcing agent inside will be noticeable.
This results in so-called whitening scratches, which reduce the commercial value of the molded product. This whitening flaw is particularly noticeable when the molded article is darkly colored, for example, black. The purpose of the present invention is to eliminate the drawback of whitening scratches in polyolefin resin moldings containing colorants and organic reinforcing agents, and to solve the problem of whitening scratches on polyolefin resin moldings that do not stand out as whitening scratches even when scratched. The purpose is to provide a manufacturing method. In the present invention, when obtaining a colored resin molded article by injection molding a polyolefin resin containing a colorant and an organic reinforcing agent, the organic reinforcing agent is previously dyed in a similar color to the coloring agent. This is a method for producing a polyolefin resin molded article. As the polyolefin resin, resins used in ordinary injection molding such as polyethylene, polypropylene (isotactic polypropylene), and derivatives thereof are used. The coloring agent used is an ordinary inorganic or organic pigment such as carbon black, which has a high affinity for polyolefin resins, and the coloring agent of the prescribed color and its usage amount are appropriately selected so that the molded article has a prescribed color. be done. As the organic reinforcing agent, ordinary organic materials such as wood flour, rice husk flour, waste paper flour, etc. are selected according to the required physical properties, and a predetermined amount is used. In addition, inorganic reinforcing agents such as calcium carbonate, plasticizers to improve moldability, stabilizers to prevent aging, etc. can be added to the formulation of polyolefin resin, but they should be used in small amounts to prevent whitening of the molded product. is preferred. Organic reinforcing agents are pre-dyed before use. Dyeing of organic reinforcing agents can be easily done by immersing a synthetic dye (especially metal-containing acid dyes are preferred) in a dye solution dissolved in water or a volatile organic solvent, or by spraying the dye solution to impregnate the dye. It can be dyed. In the case of metal-containing acid dyes, one dye molecule is coordinated to one metal atom.
There are type 1 type and 1:2 type where two dye molecules are coordinated to one metal atom, but 1:2 type has a sulfonamide group or alkyl group as a hydrophilic group. It has a sulfone group and is suitable for dissolving in neutral solvents. Examples of metal-containing acid dyes include those commercially available under trade names such as Eizenspiron (metal-containing acid dye manufactured by Hodogaya Chemical Co., Ltd.) and Lanafast (metal-containing acid dye manufactured by Mitsui Toatsu Chemical Co., Ltd.). Colors can be used. The synthetic dye used for dyeing the organic reinforcing agent has a similar color tone to that of the molded article. Suitable solvents for the dye are water or volatile organic solvents such as methanol, ethanol, methyl acetate, ethyl acetate, and acetone. In addition, regarding the dyeability of the organic reinforcing agent, when the above-mentioned organic solvent is used, the impregnating property of the dye is better than when using water, and the dyeing finish is better.
For dyeing with organic reinforcement, first dye the organic reinforcement with e.g.
After drying at 80 to 100℃, immerse it in a synthetic dye solution for about 5 minutes, take it out, and dye it with, for example, 60℃.
This is done by drying at ~80°C for about 1 hour. The dyed organic reinforcing agent may be blended with the polyolefin resin as it is, or may be directly fed to an injection molding machine at a constant ratio for use in molding a molded article. In addition, the dyed organic reinforcing agent is extruded with a polyolefin resin in an extruder to form pellets.
This may be used for injection molding. Injection molding can be carried out in the same manner as normal injection molding. However, in the present invention, when injection molding polyolefin resin, a pre-dyed organic reinforcing agent is used, so even if scratches occur on the surface of the molded product, they do not turn into whitening scratches and are not noticeable. It does not reduce the commercial value of the body. Next, examples of the present invention will be described. According to the compounding ratio shown in Table 1, each raw material was mixed uniformly in a tumbler, and this mixture was supplied to the hopper of an injection molding machine (IS90BV manufactured by Toshiba Machine Co., Ltd.) at a resin temperature of 200℃ and an injection pressure of 50Kg. /cm ² , respectively, to make control ~ as a control section and test ~ as a test section. In addition,
As raw materials for this example, the polypropylene used is BJH (product name: pellet form) manufactured by Mitsui Toatsu Kagaku, and the talc has an average particle size of 10μ, a moisture content of 0.1%, and a pH of 9.3.
The mica used had a true specific gravity of 2.63 and a whiteness of 88, and the mica had an average particle size of 90 μm and an aspect ratio of 50. Wood flour and rice husk powder are 1:2 after drying at 80℃ for 1 hour.
A type of metal-containing acid dye Eisenspiron S-Liquid (manufactured by Hodogaya Chemical, trade name, for black dyeing) was added to a 20% dye solution dissolved in methanol.
It was soaked for 1 minute, taken out, dried at 60°C for 30 minutes, and sieved.The dyed wood flour was 100 mesh passes, and the dyed rice husk powder was 60 mesh passes. The coloring agent is a colored pellet master-batched with polypropylene BJH/carbon black in a ratio of 70 parts by weight/30 parts by weight. As a control, a two-component reactive urethane paint (manufactured by Kashiyu Co., Ltd., Micron #3000G01) was applied to the surface of the injection molded plate.
1, trade name, black) was sprayed at 50 g/m ² and dried at 80°C for 20 minutes to form a black hard film on the surface. As a control, a mold with a textured surface during injection molding was used, and a pear-shaped texture was formed on the surface of the plate to prevent scratches from becoming noticeable.

[Table] Table 2 shows the results of the scratch test on the boards in the control section and the boards in the test section. The condition of the plate surface when the plate surface was subjected to a scratch test under a load of 300 g is as shown in FIGS. 1 to 8. The symbols ~ and ~ in each figure indicate each black board for testing, and A ~ A and ~
The symbol A indicates an arc-shaped white scratch made on each plate. Each actual board ~
and ~ are black, scratches A~A
and A to A are white, but in FIGS. 1 to 8, the colors of the plate and the scratches are reversed due to the drawing limitations. Control shown in Figure 1, Control shown in Figure 2, Control shown in Figure 3, Control shown in Figure 4, Control shown in Figure 5, Control shown in Figure 6, Test shown in Figure 7, Test shown in Figure 8. It can be seen that the scratches in the test and tests are less noticeable than those of each control.

[Table] The scratch test shown in Table 2 was conducted on a molded plate with a thickness of 2 mm according to JIS-A5705. That is, a plate is fixed to the turntable of a tapered scratch tester (manufactured by Toyo Seiki Seisakusho), a loaded cutting blade is applied, the turntable is rotated, and an arc-shaped scratch is made on the plate surface. The condition was visually determined. In addition, the rotational speed of the turntable is 1r.pm, the cutting blade shape is 25Rmm,
Shear angle 22°, load 100g, 200g and 300g
It was carried out in three stages. The visual judgment of the scratches was A: Not noticeable B: Slightly noticeable C: Conspicuous D: Very noticeable. It was evaluated in four stages. As is clear from Table 2, the scratches on all of the control samples were noticeable, and the scratches under a load of 300 g were particularly noticeable. On the other hand, in the tests using pre-dyed wood flour or rice husk powder, there was no whitening of the scratches and the scratches were not noticeable, which was preferable for practical use.

[Brief explanation of the drawing]

The drawing shows the state of scratches on the plate surface when the plate of the example was subjected to a scratch test with a load of 300 g, and each arc-shaped scratch is drawn at the same size as the actual test piece. FIG. 1 is an explanatory diagram of scratches made on the surface of a control plate, FIG. 2 is an explanatory diagram of scratches made on the surface of a control plate, and FIG. 3 is an explanatory diagram of scratches made on the surface of a control plate. Figure 4 is an illustration of a control scratch, Figure 5 is an illustration of a control scratch, Figure 6 is an illustration of a control scratch, Figure 7 is an illustration of a test scratch, and Figure 8 is an illustration of a test scratch. The figure is an illustration of test scratches.

Claims (1)

[Claims] 1. When obtaining a colored resin molded article by injection molding a polyolefin resin containing a colorant and an organic reinforcing agent, the organic reinforcing agent is pre-dyed with a synthetic dye in a similar color to the coloring agent. A method for producing a polyolefin resin molded article.