JPS6010904B2 - Resin injection molding method for reinforced plastics - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in a resin injection molding method for reinforced plastics (hereinafter referred to as FRP).

In general, the resin injection molding method, as explained in Figure 1, involves first cleaning and releasing the mold as part of mold preparation, then
Two or more sheets of the same type of mat-like reinforcing material made of glass fiber are stacked and spread on the lower mold, and then the mold is closed to the required extent.

Generally, both the upper and lower molds are heated to a predetermined temperature beforehand, and catalysts, accelerators, etc.
A resin mixed with an internal mold release agent, coloring agent, etc. is applied to a soft pinch-off part of the mold (packing provided around the entire circumference of the balancing part of the upper mold and lower mold to prevent resin from getting wet). The injection is continued until the air in the gap between the upper and lower molds escapes from the pores, and then the deaeration holes and the injection port are plugged. The mold is heated and hardened for a required period of time while the mold is closed, and the molded product is removed by demolding. However, since this conventional method requires a long time to inject the resin, it has not been fully satisfactory in terms of efficient use of molds and production efficiency of molded products.

As a result of various studies to improve this drawback, the present inventors used two or more types of reinforcing materials with different high specific gravity in combination so that the one with the smaller high specific gravity becomes the outer layer on the resin injection port side. It was discovered that the time required for resin injection can be shortened by stacking the materials.

That is, in the present invention, resin is injected toward the reinforcing material loaded into the gap between a pair of balanced molds, and the FR is cured by heating.
In the P resin injection molding method, two or more types of fiber sheets with different high specific gravity are used as reinforcing materials, and among them, the one with the highest bulk specific gravity is used as the outer layer facing the resin injection port provided in the mold. This is a resin injection molding method for FRP characterized in that the sheet is loaded in a thin layer between molds so as not to be disposed in the mold.

Below, embodiments of the present invention will be described in detail with reference to the drawings.
As shown in Figure 2 A, the upper mold 1 and lower mold 2 are prepared in advance for 50~
Heat it to 60℃ and add high specific gravity to the lower mold as a reinforcing material.
．． 214 poly/c fin glass chopped strand mat 3
One sheet of long glass fiber mat 4 with a high specific gravity of 0.125 yen/ground was placed on top of it.

Therefore, the side facing the resin injection port 5 becomes a mat with a low specific gravity. Next, the mold is closed as shown in the figure, and then, as shown in figure C, using a resin injector 8, inject 100 parts of unsaturated polyester resin, 0.7 part of catalyst, A mixture of 0.2 part of agent, 0.3 part of internal mold release agent, and others was injected in the required amount at an injection pressure of 3k9/m. The injection of the resin was continued until it was confirmed that the air inside the mold was sufficiently pushed out by the injected resin using a degassing row. Note that injection of the resin required about 15 minutes from start to finish. Next, as shown in Figure 2, the inlet and deaeration port each have plugs 9.
, 10 and heated at the same temperature of 50 to 60 CO for about 60 minutes. Thereafter, the mold was removed and the product 11 was taken out as shown in the diagram. In addition, in addition to this example, there are two types with different bulk specific gravity.
For example, as shown in Fig. 3, the laminated structure of the reinforcing material is as shown in Figure 3.
Medium b, large c, high specific gravity as shown in the diagram, small a, medium b, small a, high specific gravity as shown in the diagram, medium b, small a, large c, high specific gravity as shown in the second diagram, small a, medium b, medium b , bulk density small a, medium b, as shown in Fig.
Of course, you can stack them so that they are large c and small a, or you can place high specific gravity 4・a only near the inlet and place high specific gravity c in other parts, as shown in the diagram. The effect of the present invention is produced.

In addition, in order to apply the reinforcing material to the mold, one may layer the reinforcing material one by one, or two or more reinforcing materials may be glued together and applied at the same time. Furthermore, although a pair of molds generally has one resin injection port, even if there are two or more resin injection ports, the effect of the present invention can be achieved by placing a material with a high specific gravity and a small amount on the outer layer facing the injection ports. Of course, this will occur. The following table shows the results of a comparison between the present invention and the conventional method using the same mold.

This table shows that the time required for resin injection in the present invention was reduced to about 1/4 compared to the conventional method.

This is because when using the conventional method of stacking two or more sheets of the same high specific gravity, the injected resin almost fills the gaps in all directions between the fibers that make up the reinforcing material layer, as shown by the arrows in Figure 4. In contrast, in the present invention, resin with low bulk specific gravity is injected into the layer with low bulk specific gravity after layering one with low high specific gravity and one with high specific gravity, so the injected resin first penetrates and spreads at the same speed. As shown by the arrow in the opening diagram in Figure 4, it quickly and evenly spreads to the gaps within the layer with low bulk specific gravity, and then, as shown in the arrow in Figure C, the boundary between this layer and the adjacent layer with high specific gravity. This is thought to be due to the difference in the flow of the injected resin between the two, in that it penetrates from the entire surface to the layer with high bulk specific gravity. As described above, since the resin penetrates quickly in the present invention, the resin injection time can be shortened, and therefore the production efficiency of molded products can be greatly improved.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the steps of the resin injection molding method, FIG. 2 is an explanatory diagram showing each state of the process in an embodiment of the present invention,
FIG. 3 is a sectional view showing the laminated structure of the reinforcing material in the present invention, and FIG. 4 is an explanatory view showing the flow state of the injected resin. 1...Top mold, 2...Bottom mold, 3...
...Large reinforcing material with high specific gravity, 4...Small reinforcing material with high specific gravity, 5...Resin injection port. Figure 2 Figure 3 Figure 44

Claims (1)

[Claims] 1 In the resin injection molding method for reinforced plastics, in which resin is injected into the reinforcing material loaded into the gap between a pair of abutting molds and cured by heating, two or more types of fibers with different bulk specific gravity are used as the reinforcing material. The sheet-like materials are stacked and loaded between the molds so that the material with the highest bulk specific gravity is not placed on the outer layer facing the resin injection port provided in the mold. A resin injection molding method for reinforced plastics.