JPH0511734B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Field of Application] The present invention relates to an injection molding device capable of coloring a resin during injection molding.

[Prior art] In injection molding, colored synthetic resin or non-colored resin in a hopper and coloring agent are melted and kneaded by a screw in an injection heating cylinder, and this is injected into a mold to produce colored synthetic resin products. is being molded. Therefore, the coloring of the molded product is determined by the coloring of the material resin injected into the mold, and when molding a molded product with a different color, after replacing the material resin or colorant in the hopper, The residual resin inside the injection heating cylinder is discharged by emptying and replaced with new resin material.

[Problem to be solved by the invention] In order to completely change the material, several to several dozen shots of actual molding are required after emptying, and the work takes several tens of minutes and requires a large amount of resin and material. Energy is consumed.

Furthermore, in multi-cavity molds, the material resin that has accumulated in the hot runner block must be replaced with new material resin, so there is a lot of waste when changing colors, which is uneconomical, especially in high-mix, low-volume production. It is also a cause of high costs for molded products.

This invention was devised to solve the above-mentioned problems, and its purpose is to make it possible to color the resin after injecting the resin from the injection device to the hot runner, and to change the color with a slight reduction in the emptying of the resin. It is an object of the present invention to provide a new injection mold device which can injection mold molded products with different colors for each cavity using the same resin.

[Means for Solving the Problems] The feature of the present invention according to the above object is that in the nozzle part of the hot runner block provided on the fixed mold side,
A kneading member is provided close to the nozzle opening, and a colorant supply pipe is provided at the rear of the kneading member.

[Function] In the above mold device, when the molten material and coloring agent filled in the hot runner pass through the kneading member under injection pressure and are injected and filled into the mold from the nozzle part, they are mixed in the kneading member. The molten material is uniformly colored and fills the cavity.

[Example] Hereinafter, the present invention will be described in more detail by taking as an example the case of a plurality of molds.

In the figure, 1 is a movable plate that moves forward and backward to open and close the mold by a mold clamping device (not shown).A movable mold 2 is attached to the mold mounting surface, and a fixed mold is mounted to the opposing mold mounting surface of the stationary plate 3. 4 is installed.

Recesses 5 and 6 for inserting nested molds are provided on the contact surface (parting surface) of the movable mold 2 and the fixed mold 4,
A pair of fixed nesting molds 1 are formed in the nesting mold insertion recess 6 of the fixed mold 4, and a cavity 8 that forms the outer shape of the molded product 7, and a resin path 9 communicating with the cavity 8 are carved.
0 and 10 are embedded. Further, a pair of movable nesting molds 13, 13 each having a core 11 forming the inner shape of the molded product 7 and a molded product ejection mechanism 12 are embedded in the nesting mold insertion recess 5 of the movable mold 2.

The fixed mold 4 is connected to an injection device 14 provided on the back side of the fixed plate, and the natural color molten resin injected from the injection device 14 is branched and supplied to the cavities 8 of each nested mold while maintaining the molten state. A hot runner block 15 is installed inside through a heat insulating material 16, and the hot runner block 1
5, a nozzle portion 17 connected to each cavity 8, 8,
Kneading members 18, 18 called static mixers are inserted into the inside of 17, and each kneading member 1
8, 18 rear hot runners 15a, 15a
Inside, colorant supply devices 19, 19 supply liquid colorant in synchronization with the injection operation of the injection device 14.
The colorant supply pipes 20, 20 are arranged with their discharge ports facing the kneading member side.

The colorant supply devices 19, 19 are provided in the number of nested types, and colorants of the same color or different colors are supplied to each colorant supply device as necessary.

In such a mold device, a coloring agent is mixed into the natural colored molten resin injected from the injection device 14 at the rear of the nozzle portion of the hot runner block 15, and the coloring agent is further mixed in while passing through the kneading members 18, 18. and molten resin are uniformly kneaded and filled into each cavity 8,8. Therefore, in each cavity 8, 8, a molded article 7, 7 colored in the color of the coloring agent supplied corresponding to that cavity is molded.

Also, if you want to change the color of molded products 7, 7,
After replacing the colorant in the colorant supply device 19, several shots are molded, and the hot runner 15 is
The coloring agent and colored resin remaining in a, 15a and the nozzle portion are discharged. In this case, only a small amount of colored resin remains inside the nozzle,
Since there is no retention amount, colors can be changed in a short time and with a small amount of resin.

In the above embodiment, a static mixer is used as the kneading material, but the kneading member 18,
18 may be a dynamic kneading member such as a rotating screw, and the number of cavities 8 is not limited to two, but may be one or three or more. Furthermore, the molded products 7, 7 formed by the plurality of cavities 8, 8 may be of the same shape or of different shapes, and it is more suitable to use a telescoping type mold from the viewpoint of responding to diversification. However, this may be a mold with a normal structure.

[Effects of the Invention] As described above, the present invention has a mold device configured so that the molten resin can be colored within the nozzle portion of the hot runner block.
It is economical because there is no need to replace or empty the resin in the injection device each time a molded product with a different color is molded, color changes can be done in a short time, and there is less waste of resin materials, colorants, energy, etc. There is also. Furthermore, since the molded product molded in one cycle can have a different color for each cavity, it has the advantage of being suitable for high-mix, low-volume production due to diversifying user needs.

[Brief explanation of the drawing]

The drawing is a schematic longitudinal cross-sectional view of an embodiment of an injection mold according to the present invention. 1... Movable plate, 2... Movable mold, 3... Fixed plate, 4... Fixed mold, 7... Molded product, 8... Cavity, 10... Fixed insert mold, 11... Core, 13... Movable insert mold, 15...
Hot runner block, 15a... Hot runner, 17... Nozzle section, 18... Kneading member, 19... Colorant supply device, 20... Colorant kneading member.

Claims (1)

[Claims] 1. For injection molding, characterized in that a kneading member is provided in the nozzle portion of a hot runner block provided on the fixed mold side, close to the nozzle opening, and a colorant supply pipe is provided at the rear of the kneading member. Mold equipment.