JPH0674550B2 - Colorant for thermoplastic resin molded products - Google Patents

Description

TECHNICAL FIELD The present invention relates to a colorant for causing a pattern, particularly a spot or a thread pattern, to appear on the surface of a thermoplastic synthetic resin molded product.

[Prior Art] Conventionally, pigments or dyes such as pearl pigments, aluminum powder and foil fluorescent pigments have been used as colorants in order to give plastic molded articles color characteristics. However, these have not reached the point where a speckled pattern appears in a single color.
In recent years, it has become necessary to enhance the commercial value and respond to the needs of consumers by displaying not only color characteristics of a single color but also spots or thread patterns.

Generally, as a method of applying a pattern to a plastic molded product, a pattern printed on a film such as polyester or polyethylene is transferred to the surface of the plastic molded product to reveal the pattern of flowers or dolls, or screen printing is performed. It was Also, polka dots and spots were made to appear by handwriting with paint using human paint. The above-described method for displaying the pattern of the plastic molded product has complicated steps and is expensive.

At present, the only commercially available colorant for pattern appearance of plastic molded products is a colorant that uses aluminum foil cut to 0.5 mm or less in each length and width, and causes a spotted pattern to appear. However, aluminum foil is extremely expensive and opaque, and when it is used as a coloring agent for pattern appearance in plastic molded products, aluminum foil pieces are arranged vertically, horizontally or obliquely with respect to the plastic surface. However, there was an aesthetic problem as a pattern.

[Problems to be Solved by the Invention] As described above, the patterning method such as transfer and screen printing and the spot pattern colorant using an aluminum foil have various problems. As an alternative to this, colored paper or the like can be considered, but plastic molding is performed at 200 to 250 ° C and cannot be used because it carbonizes during molding. The cellulosic derivative cellophane film or viscose rayon is a composition of 65 to 96% by weight of cellulose, 0 to 25% by weight of a softening agent, and 4 to 10% by weight of water, particularly a large amount in the cellulose.
When used in a plastic molded product containing an OH group and subjected to high-temperature molding as described above, -OH in the cellulose is hygroscopic, so even if it is sufficiently dried and added to the resin, it is mixed and molded from the atmosphere. Since the adsorbed water causes flashing on the surface of the molded product, its use has never been considered. The present inventor has conducted intensive studies paying attention to such a point, is inexpensive, and is a simple process that does not change the plastic molding process and conditions. The pattern of a thermoplastic resin molded product having a transparent pattern. The purpose is to provide a coloring agent for development.

[Means for Solving the Problems] As described above, cellophane film or viscose rayon, which is a conventional viscose derivative, has a large OH group content and is hygroscopic. Although it was thought to be unsuitable as an agent, as a result of earnest research, it was dyed with a reactive dye among various dyes to block a large amount of viscose OH groups by reaction. The inventors have completed the present invention, finding that it is possible to prevent the occurrence of flashing due to adsorbed moisture on the surface of molded articles.

That is, the present invention is to provide a coloring agent for pattern appearance of a thermoplastic resin molded article, which is composed of cellophane film or viscose rayon which is a viscose derivative dyed with a reactive dye.

The configuration of the present invention will be described in detail below.

As the viscose derivative cellophane, a commercially available undyed product is used. Viscose rayon is a viscose fiber and has the same composition as cellophane.
For rayon, use undyed products of 150 denier or less. 150
A denier or more is not preferable because when it is added to the thermoplastic resin, the surface of the molded article becomes rough. Cellophane and viscose rayon each preferably have a length and width of 6 mm or less. If the size exceeds 8 mm, it will be bent or twisted when mixed with resin, which is not preferable.

Commercially available products of various colors are used as the reactive dye. A method for dyeing cellophane film or viscose rayon with a reactive dye is performed by a person skilled in the art. That is, warm water is added to the reactive dye and the pH is adjusted with sodium carbonate, etc.
Is made slightly alkaline to about 8 and mirabilite is added to enhance the dyeing effect. The cut cellophane or viscose rayon is added to this solution, and the mixture is stirred, dehydrated, washed with water, dried and dyed. In this case, the reactive dye is added in an amount of about 2 to 5% by weight for dyeing. If it is within this range, the -OH group in cellophane film or viscose rayon can be blocked.

The reaction in this case is represented as a model as follows.

Examples of the thermoplastic resin include polystyrene, acrylo-styrene, acryl, ABS, polycarbonate, polyvinyl chloride, polyethylene, polypropylene, polyethylene terephthalate, and polybutylene terephthalate.

Before molding these thermoplastic resins, the colorant for pattern expression of the present invention is added to the thermoplastic resin heated to 200 to 250 ° C., and after mixing, injection molding or hollow extrusion molding is performed. In this case, since cellophane or viscose rayon is light and easily scattered, it is preferable to add oil or the like when mixing with the resin to prevent the scattering. The addition amount of cellophane or viscose rayon to the resin is preferably 5% by weight or less. If the amount added exceeds 5% by weight, the cut pieces will overlap and it will be difficult to form a single pattern.

(Example) Next, although the aspect of this invention is demonstrated using an Example, these do not limit this invention to them.

Example 1 (Production of colorant for pattern appearance) Cellophane: Nimura Chemical Co., Ltd. product cut into 3 mm square and 0.5 mm square viscose rayon: Asahi Kasei Co. product 100D, 50D, 15
Cut D, 5D to each length of 5mm, 2mm, 0.5mm.

Each substance was added to these in the following composition ratios.

Each of the above cut products 100g Sodium carbonate 7 Glauber's salt 5 Reactive dye (Nippon Kayaku Co., Ltd. product Mikasion Orange G
S, Red GS Blue RS) 6 Warm water (40 ° C) 400cc Mixing and stirring the above mixture at 40 ° C for 15 minutes, dyeing treatment,
Dehydration, washing with water (three times), and drying were performed to obtain a coloring agent for pattern expression.

Example 2 (Manufacture of Thermoplastic Resin Molded Product with Pattern-Use Case of Cellophane) (1) 100 parts of styrene resin (product of Nippon Steel Co., Ltd.) Colorant for pattern development 1 (Cellophane) Fluid Paraffin 1 The mixture was mixed by a drum tumbler machine for 15 minutes and then injection molded to produce a molded product.

(2) Acrylic resin 100 parts Colorant 1 for pattern appearance 1 (cellophane 3 mm square, red, yellow, and blue in a ratio of 1: 1: 1) Liquid paraffin 1 A molded product was produced in the same manner as (1).

(3) Polypropylene resin 100 parts (product of Tokuyama Soda Co., Ltd.) Colorant for pattern appearance 1 (cellophane 0.5 mm square) titanium oxide 0.5 fluid paraffin 1 A molded product was manufactured in the same manner as (1).

In (3), a white opaque molded product and a powdered cellophane colored product became a wonderful molded product with a spotted pattern and a warm taste.

As a result of visually observing the above-mentioned molded product, both (1) and (2) clearly showed cellophane transparent coloring matter inside the transparent molded product and expressed a satisfactory pattern.

Example 3 (Production of thermoplastic resin molded product with pattern-use case of viscose rayon) ABS, styrene or PP resin 100 parts Colorant for appearance of the above pattern (viscose rayon, black, red) Titanium oxide 1 Fluid paraffin 1 A molded product was produced by injection molding a drum tumbler in the above proportion.

The results are shown in Table 1.

No flashing due to adsorbed water was observed in any of the molded products.

Like cellophane, rayon can be mixed into a master batch or processed into granules.

[Effects of the Invention] Although the effects of the present invention are excellent and are extremely useful, the specific examples are apparent from the above-mentioned examples, but they are summarized as follows.

(1) By using the colorant of the present invention in a thermoplastic resin molded product, a spot or a thread-like pattern can be revealed.

(2) The colorant for showing the pattern of the thermoplastic resin molded product of the present invention is extremely inexpensive as compared with the conventional colorant using an aluminum foil or the like.

(3) Compared with the conventional pattern revealing method, the pattern can be revealed in a simple process without changing the plastic molding process and conditions.

(4) Blocking OH groups in cellophane film or viscose rayon by dyeing with a reactive dye,
It was possible to prevent flushing due to adsorbed moisture on the surface of the molded product.

Although it was considered to be unsuitable as a coloring agent for conventional pattern appearance due to this, this has been solved.

(5) Compared to the conventional aluminum foil colorant, the colorant of the present invention is characterized by being transparent and having a very clear color tone.

(6) With conventional aluminum foil colorants, the arrangement state was not constant in the vertical, horizontal or oblique directions with respect to the plastic surface. However, when the colorant of the present invention is used in a thermoplastic resin, cellophane or Viscose rayon is aligned horizontally with the plastic surface and shows a uniform arrangement, which is aesthetically superior. The reason for this is not clear, but it is presumably because cellophane or viscose rayon is easily aligned horizontally on the plastic surface due to the gravity of compression during molding.

Claims (1)

[Claims] 1. A viscose derivative cellophane film or viscose rayon dyed with a reactive dye.
Colorant for the appearance of patterns in thermoplastic resin moldings.