JPH0511730B2 - - Google Patents

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is a method for producing molded products by collision-mixing raw materials stored in a plurality of raw material tanks in an injection head under high pressure and injecting the mixture into a mold. The present invention relates to a method for coloring a molded product in a reaction injection molding machine during production by reaction curing.

[Problems to be solved by conventional technology and invention]

As a method for coloring products in a urethane reaction injection molding machine, there is a raw material coloring method in which a pigment is mixed into a raw material liquid in advance. However, in this method, when handling multiple colors, the raw material storage tank,
Large-scale equipment such as pumps is required for each color. In addition, in order to ensure the physical properties of the product, there is a limit to the mixing rate of pigments, and it is not possible to freely adjust the color tone, gloss, etc.

Furthermore, there is a coating method in which the molded product is spray-painted in a separate process, but this requires a separate coating process and increases equipment costs.

Therefore, an object of the present invention is to provide a coloring method for a reaction injection molding machine that ensures molding quality in reaction injection molding and colors in an inexpensive manner.

[Means and actions for solving problems]

In order to achieve this object, the present invention stores the fluid pigment in a dedicated tank and, during injection molding, injects the fluid pigment from the side into the runner section extending from the injection head to the mold. The material was extruded toward the mold surface, and injection of the raw material was started immediately after this injection. As a result, the fluid pigment is extruded toward the mold surface, mixed with the subsequent mixed raw material to cover the mold surface, and the mixed raw material is extruded from behind to produce a molded article.

[Embodiments of the invention]

FIG. 1 shows a urethane reaction injection molding machine for carrying out the coloring method of the present invention. In the same figure, 1
1 is a tank for storing isocyanate, and 1a is a tank for storing polyol, each of which is equipped with a pump 2, 2a and a metering cylinder 3, 3a controlled by a hydraulic unit 5. Reference numeral 4 denotes an injection head controlled by a hydraulic unit 5, which collides and mixes the raw materials supplied from the measuring cylinders 3 and 3a, and extrudes the raw materials into a mold 6 consisting of fixed and movable molds 6b and 6c.

Such a structure is the same as the conventional one, but according to the present invention, there is also a pigment tank 1 that stores three types of pigments dissolved in polyol at high concentrations.
0, 10a, 10b and their respective attached pumps 11, 11a, 11b and measuring cylinder 1
Three pigment supply pipes 13, 13a, 13b are attached to the fixed side wall of the runner part 6a of the mold 6 which follows the injection head 4. And each of these parts 11 to 11b, 12
- 12b, which selectively pumps these three types of pigments to the runner section 6a, generates a main body control signal immediately after injection, and controls the original devices 2, 2a, 3, 3a, Step 4 performs the raw material injection operation.

The operation of the reaction injection molding machine configured as described above will be explained with reference to it.

Through the setting operation of the control device 14, for example, a pigment in the pigment tank 10b is selected, and the pigment pumped by the pump 11b is passed through the pipe 13b in an amount necessary for the specified surface coloring by the measuring cylinder 12b, and a small amount is transferred to the runner section 6a. Immediately after that, the original operation is performed to transfer a specified amount of raw material from the tanks 1 and 1a from the injection head 4 to the runner section 6a.
(FIG. 2a) and pressed into the mold 6.
This results in an initial injection of pigment (FIG. 2b) followed by an initial portion of raw material from behind (FIG. 2c). This portion is mixed with pigment during the extrusion process and covers the inner surface of the mold 6, and the raw material portion located at the rear is injected in turn (FIG. 2d).
Therefore, reaction curing is performed in the mold 6 including the compatible pigment from the tank 10b, and a molded product whose surface is colored only is manufactured.

When performing another coloring, the control device 14 is caused to carry out high-pressure pumping of the pigment stored in another pigment tank 10 or 10a.

It should be noted that the additional pipes for the pigment can be provided in the movable mold, and in some cases it is also conceivable to provide an adjacent part between the injection head and the mold and to provide the additional pipes vertically or radially in the same horizontal plane. The present invention is also applicable to other types of reaction injection molding machines, such as those for nylon.

〔Effect of the invention〕

As described above, according to the present invention, since it is only necessary to stock the fluid pigment for the number of colors, the equipment can be smaller than in the raw material coloring method. In addition, since only the surface layer of the product can be colored without the need for a painting process, it is possible to increase the pigment content without deteriorating the physical properties of the product due to pigments, and the color tone can be adjusted as freely as with painting, giving it a glossy appearance. You can get a product with The amount of pigment required is also small compared to raw material coloring and spray painting methods.

[Brief explanation of the drawing]

FIG. 1 is a diagram showing a schematic configuration of a urethane reaction injection molding machine that implements the coloring method according to the present invention, and FIG.
The figure is a diagram showing the operation process. 1, 1a... Raw material tank, 4... Injection head, 6...
Mold, 6a...Runner part, 10, 10a, 10b...
pigment tank.

Claims (1)

[Claims] 1. Coloring in a reaction injection molding machine that produces a molded product by reaction curing by collision-mixing raw materials stored in a plurality of raw material tanks in an injection head under high pressure and injecting the mixture into a mold. A method in which a fluid pigment is stored in a special tank, and during injection molding, the fluid pigment is injected from the side into a runner section extending from an injection head to a mold, and raw materials are injected immediately after this injection. The coloring method that started the process.