JPH0674551B2 - Colorant for thermoplastic resin molded products - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial field of application) The present invention relates to a specific colorant for producing patterns, particularly speckled and 1 or flow patterns (marble) on the surface of a thermoplastic synthetic resin molded article. Regarding

(Prior Art) In various plastic molded products, it has already been performed to give characteristics by changing the shape and the like and to give specificity to colors in order to improve the performance. However, until now, the coloring of thermoplastic resin moldings varies depending on the type of product, but most monochromatic products consisting only of dyes and pigments produce unevenness by providing unevenness on the surface. Good time.

On the other hand, it has been generally known and carried out to produce a spotted pattern, but the method is, for example, using an aluminum foil and its colored product cut to a size of about 0.5 × 0.5 mm or a mica powder. The coloring matter is added, and the case where an inorganic coloring material is used is mainly used.

However, this aluminum foil cut product is very expensive,
Further, the mica powder has a drawback that the peeling bleeding of the coloring material and the particle size become unstable due to insufficient surface strength.

In addition, as a method of producing a marble-like flow pattern, conventionally it was necessary to use a plunger type molding machine and further increase the size of the mold's gaiter, which is a commonly used inline screw type Was unusable.

In this case, a colorant having a high melting point is used,
A master batch is made of a resin that has a lower MI (melt index) than the molding resin and does not flow easily (not a resin that is crosslinkable, of course), and coloring and pattern development are performed using the special machine described above. However, there was a drawback that it was difficult to control the coloring and pattern flow.

As an alternative method, use a molding machine with two screws to make the mold on two sides, mold one color with one screw, then transfer the mold to the other screw side and double mold another color. There is a way to do it. In any case, the colorant has no peculiarity, and it can be said that such a pattern has been produced only by the peculiarities of the molding method and the molding machine.

(Problems to be Solved by the Invention) As described above, there are various problems in the colorant for developing the spot pattern, and on the other hand, in the commonly used screen type molding machine, a marble-like flow pattern is provided. Although no excellent coloring agent has been found, the present invention has been completed as a result of intensive studies focusing on this drawback, and the purpose thereof is that it is inexpensive especially for thermoplastic resin molded products. Another object of the present invention is to provide a colorant that can easily produce spot patterns or flow patterns on a general molding machine without changing the molding conditions.

(Means for Solving the Problems) That is, the colorant of the present invention is a thermoplastic resin or elastomer that undergoes a cross-linking reaction with an organic oxide, in which a dye / pigment and an organic peroxide are blended. Although mainly used for spot patterns, an appropriate amount of ordinary thermoplastic resin having no cross-linking reactivity can be added to this composition, and various flow patterns can be obtained by adjusting the addition amount. You can also

The colorant can be added to the thermoplastic resin for molding at a ratio of 5% by weight or less and molded to form a pattern on the surface of the molded product. Regarding the colorant and the production thereof, various kinds of thermoplastic resins or elastomers can be used, and the main point is that they have a crosslinking reactivity with an organic peroxide.

Regarding this thermoplastic resin or elastomer, a resin having a relatively large molecular weight, which is equivalent to or close to that of the molding resin, is suitable mainly for the appearance of spotted patterns, and as the molecular weight becomes lower, it is suitable for flow patterns. In this case, for example, those having a relatively small molecular weight have a low softening point and are easy to handle, but those which do not decompose at the molding temperature, that is, the molding temperature of the resin is about 250 ° C., so it is necessary to select a material having a higher temperature. Incidentally, in order to obtain the flow pattern, of course, there is also an aspect in which a resin having no crosslinkability is added as described later.

The above colorant resin or elastomer is used in any form of a homopolymer (homopolymer) copolymer (copolymer) and a mixture thereof.

Examples of the types thereof include high-pressure medium-low-pressure polyethylene, ethylene-propylene rubber (EPR), ethylene vinyl acetate copolymer (EVA), and ethylene butadiene elastomer.

An organic peroxide is used as a crosslinking agent for these resins. Examples of the organic peroxide include ketone peroxides, alkyl peroxides, hydroperoxides, dialkyl peroxides, alkylaryl peroxides, peroxyketals,
Alkyl peresters, peroxycarbonates and the like are available, but dicumyl peroxide, tributylbenzyl peroxide and the like are particularly preferably used.

The degree of crosslinking of the resin can be adjusted by the amount of the crosslinking agent used. As one example, the following table (Table 1) shows the ratio of the resin of the coloring agent having spots and the organic peroxide.

In addition, the amount of the peroxide added is more than the maximum amount, which is useless, and becomes liquid (paste-like) in the roll and the extruder, which makes it difficult to process, and when the amount is less than the minimum amount, all are compatible and do not form a spot pattern.

Next, regarding dyes and pigments, commercially available products for plastics can be widely used, and the amount thereof can be appropriately increased or decreased depending on the shade of the pattern or the like to be obtained.

In addition, in the production of the colorant, for example, a resin that is solid at room temperature,
After adding an organic peroxide and dyes and pigments and kneading with a heating roll, an extloader, etc., a method of pulverizing or pelletizing into 10 to 20 mesh is used. Fillers can be added.

Above, the blending of the colorant for spotted pattern development was mainly described, but in the present invention, the flow pattern is developed by adding an appropriate amount of a normal thermoplastic resin having no crosslinking reactivity to the formulation. Can be done. An example of the composition is shown in the following table (Table 2).

Next, in the method of developing a pattern on the surface of a molded article using this colorant, the range of molding thermoplastic resin used is soft and hard polyethylene, polypropylene, methacrylic resin, ABS resin, nylon resin, chloride Vinyl resins, polyethylene terephthalate (PET), polybutylene terephthalate (PBT), polycarbonate resins and the like are a group of resins having a high molecular weight (average molecular weight of 20,000 to 150,000) generally used for molding. It is shown in Table 3 when displayed.

Then, in order to reveal the pattern, the colorant is added to the molding resin in a ratio of 5% by weight or less, and molding is performed.
Here, the reason for the content within 5% by weight is that the colorant has almost no compatibility with the molding resin due to crosslinking, and if the amount is more than this, separation, peeling and This is because the physical properties are deteriorated, but when used in an amount of 5% by weight or less, the peeling phenomenon does not occur and the physical properties are not deteriorated.

Depending on the degree of compatibility of the colorant with the molding resin, a spot pattern or a flow pattern is formed. Therefore, the pattern can be easily adjusted by appropriately selecting the combination of the two.

For example, the appearance of a spotted pattern is one that is completely incompatible with the molding resin and does not decompose and melt at the molding temperature, and the particle size is preferably 10 to 20 meshes and more scaly than spherical, but the flow pattern is In order to obtain it, a resin that is somewhat compatible with the molding resin but is incompatible with most (80% to 90%) is required.

In the present invention, this compatibility problem is caused by the cross-linking agent and the degree of cross-linking (such as partial cross-linking or complete cross-linking) during the production of the colorant as described above.
It is possible to change it by adjusting appropriately.

The preferable molding method used in the pattern expression of the present invention is injection molding, blow (hollow) molding, and extrusion molding, and all can be carried out by a conventional method using a known model.

In addition, in the case of only the spotted pattern, the molding can be carried out only by adding the coloring agent to the molding resin, but as an alternative method, it is also possible to carry out the molding after forming the colored pellet from the coloring agent and the molding resin.

(Example) The present invention will be described in more detail with reference to the above examples.

Example 1 Dicumyl peroxide was added to high-pressure polyethylene (Nippon Yunika F-161) in an order of 0.02 to 2% by weight, and 10% of pigments such as carbon black, titanium oxide and cyanine blue were mixed. , Heating roll 180 ° ~ 2
Kneaded at 20 ° C. After cooling, it was pulverized into 3 to 5 mm square to prepare a coloring agent. 0.5 parts of this colorant and 1 part of white dry color were added to 100 parts of the molding resin described below, and injection molding was carried out to reveal a pattern.

As a result, when dicumyl peroxide was 0.2 to 2%, a clean small speckled pattern appeared, and
At 0.02 to 0.2%, the pattern flow occurred due to the mixed state with the material compatible with the spots.

Example 2 A medium- and low-pressure polyethylene (Nippon Unica M-680) was used to prepare a colorant under the same conditions as in Example 1 and injection molding was performed to reveal a pattern. The results showed almost the same tendency as in Example 1. It was

Example 3 Ethylene-propylene rubber (Nippon Synthetic Rubber EP-579)
On the other hand, a colorant was prepared under the same conditions as in Example 1 except that the ratio was sequentially changed so that dicumyl peroxide was 0.02 to 2.5% by weight, and injection molding was performed to reveal a pattern. , Dicumyl peroxide 0.5-2.5%, a small speckled pattern appears, and the same peroxide 0.02-
When it was 0.5%, the spots and the compatible material were mixed, and some pattern flow occurred.

Example 4 Coloring under the same conditions as in Example 1 except that the ratio of dicumyl peroxide to ethylene-vinyl acetate copolymer (Mitsui Polychemical EVA) was sequentially changed so as to be 0.02 to 3% by weight. When the agent was made and injection molding was performed to reveal the pattern, the result was that a clean speckled pattern was revealed when the concentration of dicumyl peroxide was 0.6 to 3%, and in other cases, mixing of the speckle and partial compatibility was observed. A pattern flow occurred.

Example 5 Example 1 except that the ratio of dicumyl peroxide to styrene-butadiene elastomer A (Asahi Kasei Tuffprene A) was sequentially changed to 0.01 to 1.5% by weight.
A colorant was prepared under the same conditions as described above. 0.5 parts of this colorant and 1 part of white dry color were added to 100 parts of the molding resin described below, and injection molding was performed to reveal a pattern.

As a result, a small speckled pattern appeared when dicumyl peroxide was 0.7 to 1.5%, and the peroxide was 0.01 to 0.
At 7%, the mixture with the spots and the compatible material became mixed.

Example 6 A colorant was prepared under the same conditions as in Example 5 with respect to ethylene butadiene elastomer B (Asahi Kasei Sorprene T-414), and injection molding was performed to reveal a pattern. The results were also as in Example 5. It showed a similar tendency.

Example 7 100 parts of each formulation of Example 3 and 10 parts of pigments 100 parts, 200 parts, and 400 parts of calcium carbonate were prepared as additive colorants, respectively.
The results of injection molding were almost the same as in Example 3.

Example 8 A colorant was prepared based on the compounding formulation of Example 4 under the conditions of Example 7, and the result of injection molding was almost the same as that of Example 4.

Example 9 1% by weight of dicumyl peroxide and 35% by weight of polypropylene based on high-pressure polyethylene (Nippon Unica F-161)
And the pigment is added and mixed at a ratio of 10% by weight, and heated roll 180
After kneading at a temperature of ° to 220 ° C, the mixture was cooled and pulverized to about 3 to 5 mm square to prepare a coloring agent. 100 parts of the same resin as used in Example 1 was mixed with 1 part of the colorant and 1 part of the white pigment and injection-molded to reveal the pattern. As a result, a clean flow pattern was obtained.

Example 10 A medium- and low-pressure polyethylene (Nippon Unica M-680) was prepared with a colorant under the same conditions as in Example 9 and injection-molded to reveal a pattern. Got

Example 11 A colorant was prepared under the same conditions as in Example 9 except that dicumyl peroxide was used at a ratio of 1.3% by weight with respect to ethylene propylene rubber (Nippon Synthetic Rubber EP-579), and an injection molded pattern was obtained. As a result, the flow pattern was obtained in the same manner as in Example 9.

Example 12 A colorant was prepared under the same conditions as in Example 9 except that dicumyl peroxide was used in a ratio of 1.7% by weight with respect to an ethylene vinyl acetate copolymer (Mitsui Polychemical EVA), and injection molding was performed. When it was exposed, a pattern was obtained as in Example 9.

Example 13 Styrene butadiene elastomer A (Asahi Kasei Toughprene A) was added with 25% by weight of styrene resin and polypropylene 35.
A colorant was prepared under the same conditions as in Example 9 except that the amount was replaced by weight%, and injection molding was performed to reveal a pattern.
A flow pattern was obtained in the same manner as in Example 9.

Example 14 A styrene-butadiene elastomer B (Asahi Kasei Sorprene T) was mixed with 25% by weight of an acrylic resin and 35% of polypropylene.
A colorant was prepared under the same conditions as in Example 9 except that the amount was replaced by weight%, and injection molding was performed to reveal a pattern.
A flow pattern was obtained in the same manner as in Example 9.

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Claims (2)

[Claims] 1. A coloring agent for producing a pattern in a thermoplastic synthetic resin molded article, which comprises a dye or pigment and an organic peroxide blended with a thermoplastic resin or an elastomer which undergoes a crosslinking reaction with an organic peroxide. 2. A coloring agent for pattern appearance of a thermoplastic resin molded product, which is obtained by adding a thermoplastic resin having no cross-linking reactivity to the composition of claim 1.