JPH047109A - Method for forming synthetic resin product - Google Patents

Abstract

PURPOSE:To form a synthetic resin product, which has depth in color and is full of high-class impression, by a method wherein plastic particles, the color of which is different from that of base plastic sol, is mixed with the base plastic sol without being melted so as to adhere the resultant sol in the form of film to the inner surface of a mold and, after that, gelling by heating. CONSTITUTION:Colored plastic sol is fed in each one of a plurality of pairs of molds 1, which are provided on a rotatable stand 2 and, after the closing of the molds, rotated in a heating oven so as to be adhered in the form of uniform film to the inner surface of the molds 1 and finally gelled by heating in order to form a colored synthetic resin product 3 having uniform film thickness. As the plastic sol to be fed, base plastic sol mixed with plastic particles, the color of which is different from that of the base plastic sol, is used. The plastic particle has nearly the same composition as that of the base plastic, is composed to be different from the base plastic in color by the difference between colorants, is used in the form of powder having the mean particle diameter of about 0.1 - 0.3 mm by being mixed at the mixing ratio of 50 wt.% or less with the base plastic sol.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a method for molding colored synthetic resin products that exhibit a unique color due to the mixture of plastic particles in a semi-molten state.

(Prior Art) Vehicle headrests, toys, and the like made of synthetic resin are usually molded by rotational molding or slush molding using plastic sol as a raw material.

However, when colored synthetic resin products are molded using rotational molding or slush molding using plastic sol as a raw material, the coloring agent is uniformly melted into the plastic sol, resulting in a single color with no depth and high quality. There is a problem that they tend to lack a sense of appearance, and are not suitable for colored synthetic resin products that are used as decorations and require a high-class feel, as has been the case in recent years.

(Problems to be Solved by the Invention) The present invention solves the above-mentioned conventional problems, and uses rotary molding and slush molding to produce a variety of decorative items with deep colors and a luxurious feel. This was completed with the aim of providing a method for molding synthetic resin products that can be used in other applications.

(Means for Solving the Problems) The method for molding synthetic resin products according to the present invention, which was made to solve the above problems, involves melting plastic particles of a different color into a base plastic sol. It is characterized in that it is mixed without any heat, and then it is attached to the inner surface of the mold in the form of a film and heated to gel.

(Example) Next, a case in which a rotary molding mold illustrating an example of the present invention is used will be described in detail.

(1), (1) are molds arranged in plural pairs on a rotatable table (2), and after supplying the colored plastic sol into the molds (1), (1), the second Mold (1) as shown,
(1) is rotated in a heating furnace (not shown) in a closed state to adhere it as a uniform film to the inner surface of the mold (1), (1), and then heated to gel and colored to have a uniform film thickness. This method molds a synthetic resin product (3), and the above points are similar to the conventional rotational molding method, but in the present invention, a plastic sol of a different color is added to the base plastic sol to be supplied. Use one mixed with particles. The plastic sol used as a base is DOP (
di2-ethylhexyl phthalate), DBP (dibutyl phthalate), DOA (diethylhexyl adipate)
In addition, a material consisting of 40 to 100 parts by weight of a plasticizer, 2 to 5 parts by weight of a stabilizer, 0 to 30 parts by weight of a filler, and 1 to 3 parts by weight of a colored material is used, depending on the characteristics of the raw material resin.

On the other hand, the plastic particles to be blended into the above-mentioned plastic sol are particles with an average particle size of 0.1 to 0°311II11, which have almost the same composition as the base plastic, but are blended so that only the coloring agent is different, giving them a unique color. These uniquely colored plastic particles are mixed into the base plastic sol at a weight ratio of 50% or less. In addition, if more than 50% is mixed, it becomes difficult to mix uniformly, and variations in wall thickness tend to occur, making it difficult to obtain a product with a uniform thickness.

Next, as described above, a sol-like resin raw material in which plastic particles of different colors are mixed into a base plastic sol is fed into the molds (1) and (1) for rotational molding. As shown in the figure, the plastic particles (4) are heated and gelled in the base plastic (5) so that they are not completely melted but have an unmelted part (7) covered with a melted layer (6) on the outer surface. Process. The conditions for such heating gelling treatment vary depending on the thickness of the product to be molded, the diameter of the plastic particles to be mixed, the heating temperature and heating time, etc., and are set at the actual molding site. To mold a product, the average particle size of the plastic particles should be 0.2 mm, and the heating temperature should be 180°.
C±10°C1 heating time may be about 5 minutes. Thereafter, the molds (1), (]) are cooled, and the colored synthetic resin product adhering to the inner surface of the mold in a film is taken out, and the same procedure is repeated thereafter.

The colored synthetic resin product (3) molded in this way is
The whole body is colored with a coloring agent that is completely melted in the base plastic (5), and at the same time, the surface is mixed with unmelted parts (7) of plastic particles of a different color, which is different from the conventional single color. You can get something more interesting in terms of color compared to just one color. Moreover, since a molten layer (6) in which plastic particles of a different color are melted is formed around the outer periphery of the unmelted part (7), a colored layer with a shading pattern is formed around the unmelted part (7). As a result, you can obtain a product with a deep and luxurious feel. Furthermore, since the plastic particles (4) mixed in the base plastic (5) have a similar composition to that of the base, the strength of the product deteriorates, unlike when foreign substances such as sand or metal particles are mixed in. For example, the tensile strength of 80 kg/ci, the elongation at break of 170%, and the tear strength of 30 kg/cm, which are the standards for vehicle seats, are 138 kg/cm+.
Fl, 286%, and 49.4 kg/cm were all obtained. In addition, in the examples, molding of colored synthetic resin products by rotational molding was explained, but a so-called slush molding method is used in which a large amount of plastic sol is supplied into the inside of the mold and then the excess plastic sol is discharged from the mold. You can also do that.

(Effect of the invention) As is clear from the above explanation, in the present invention,
Plastic particles of a different color are mixed into the base plastic sol without being melted, and then attached to the inner surface of the mold in a film form and heated to gel, resulting in deep colors and a luxurious feel. As a molding method for synthetic resin products that eliminates the problems of conventional methods,
The contribution to industrial development is extremely large.

[Brief explanation of drawings]

1 and 2 are process explanatory diagrams of an embodiment of the present invention, and FIG. 3 is an enlarged sectional view of a product obtained by the present invention. (4) Niblastic particles, (6): Melted layer, (7):
Unmelted part.

Claims (1)

[Claims] A method for molding synthetic resin products that involves mixing plastic particles of a different color into a base plastic sol without melting them, and then attaching them in a film form to the inner surface of a mold to heat them into a gel.