JPS6122914A - Integral molding method of synthetic resin and fibrous sheet - Google Patents

Abstract

PURPOSE:To prevent breaks and wrinkles from developing by a method wherein a fibrous sheet is placed in advance in a bottom force and plasticized synthetic resin is put into the sheet and finally the bottom force is closed by a top force in order to be molded integrally under pressure. CONSTITUTION:Firstly, a fibrous sheet 2 to be integral with resin is placed so as to be positioned onto the inner bottom surface of a bottom force 4b. Secondly, the extrustion nozzle of an extruder is moved to a position above the force in order to put plasticized synthetic resin 1 into the sheet. Thirdly, the bottom force is closed by a top force 4a in order to press-mold the sheet with resin. Consequently, because the resin can flow with small force during press molding, woven paper and cloth, both of which have comparatively litttle strength and rigidity, are scarce to be broken and wrinkled.

Description

[Detailed description of the invention] (a) Purpose of the invention [Field of industrial application] The present invention relates to a method for integrally molding a fibrous sheet such as paper or cloth on the surface of a synthetic resin without using adhesives or the like. The object of this invention is to obtain a molded product of this type that is firmly joined.

[Conventional technology]

In order to join other sheets to the surface of synthetic resin, it is common to use adhesives to join pre-formed and manufactured synthetic resin molded products, but this is very time-consuming and does not work well with polyethylene, polypropylene, etc. In the case of resins such as, it was difficult to obtain strong adhesive strength.

However, with the advancement of injection molding and other techniques, the insert method is used to join synthetic resin films, for example, [133-31
An integral molding method as shown in Japanese Patent No. 80 has come into use.

In this method, to form a decorative pattern, a transparent thermoplastic synthetic resin film with letters, etc. printed on the upper surface is tightly sealed upward on the inner bottom surface of the female mold.
Next, the female mold and the male mold are closed, and a molten M&+4 material of a thermoplastic synthetic resin is press-fitted between the male and female molds while cooling with water to perform integral molding.

[Problems to be Solved by the Invention] As mentioned above, the injection insert molding method is already known for synthetic resin films and sheets, but it has the drawback of tearing and wrinkles during the press-fitting stage, and the side-opening type. In some cases, the positioning of this sheet within the mold did not go well.
At the very least, this method was time-consuming and was not always successful in the case of paper or cloth.

This is precisely the problem that the present invention aims to solve, and as a result of various studies, the inventors of the present invention have solved this problem and created a new integral molding that does not tear or wrinkle even with relatively weak paper or cloth. The present invention was achieved by developing a method.

(0) Structure of the Invention [Means for Solving the Problems] One of the present inventions is, in order to improve the above-mentioned drawbacks, to place a fibrous sheet in advance in a lower mold, and to synthesize a plasticized sheet onto it. After placing the resin, the upper mold is closed and molded under pressure.
In the other method, plasticized synthetic resin is placed on top of the plasticized resin outside the mold, which is then brought into the lower mold, the upper mold is closed, and the same molding is carried out under pressure.

Synthetic resins include polypropylene, polyethylene, A
Thermoplastic materials such as BS, nylon, polystyrene, and acrylic resin can be used, but it goes without saying that this method is particularly effective for resins that are difficult to bond with adhesives, such as polypropylene, polyethylene, and tyrene. Nor. It is also possible to add fillers such as glass fiber, talc, mica, etc. to these synthetic resins, if necessary.

Examples of the fibrous sheet include paper and textiles, but also nonwoven fabrics, and the material of the fibers may be either natural fibers or synthetic fibers. It is particularly useful for items that have low strength and rigidity, are difficult to handle using conventional methods, are easily torn, and have wrinkles. It is best to use an extruder for the step of placing synthetic resin on the fibrous sheet, and the conditions for doing this are, for example, when using polypropylene, the resin heating temperature is 150-250°C.
The temperature at 40℃ is lower than that of normal injection molding, and
The pressure when closing the mold is also 50 kQ/0112-1
It is possible in the range of 000 ko/cm2.

Furthermore, in the method of placing the synthetic resin outside the mold, the resin is supplied from an extrusion nozzle of an extruder at a fixed location, but the method of conveying the resin is outside the mold using a belt conveyor. The mold temperature is controlled by taking into account the distance to the mold, etc.

To further explain the above method using drawings, first, the fibrous sheet 2 to be integrated with paper or cans, etc. is positioned and placed on the inner bottom surface of a lower mold 4b as shown in FIG. The nozzle is directed onto the mold and the plasticized synthetic resin 1 is placed thereon.

This step can also be carried out while moving the position of the extrusion nozzle (see FIGS. 6 and 7). Next, the upper mold 4a is closed and pressure molding is performed as shown in FIG.

The heating and cooling method for solidifying the mold is determined by taking into account the type of synthetic resin, the shape of the molded product, etc.

Although the case where the paper or cloth is attached to only one side of the synthetic resin has been described above, it is also possible to further place paper or cloth on the plasticized synthetic resin and attach it to both sides. In this case, it is also possible to use a method in which paper or cloth is previously held inside the upper mold 4a until the mold is clamped.

Although the explanation has been given using a flat product as an example, the present invention is not limited to this, and can of course also be used for molding a fish-shaped product.

Next, the method of applying the plasticized synthetic resin onto the Il fibrous sheet outside the mold is as shown in Fig. 8, using the conveyor belt 7.
This is carried out by an extruder 5 from a certain point above. The operation can be carried out smoothly intermittently by matching the resin placement time with the mold opening/closing time.

The peel strength of the product thus obtained is usually 370 to 560 g/am when polypropylene and Japanese paper are integrated.

〔Example〕

Examples of the present invention are as follows.

Example 1 Length 230111111, width 98ml1 and thickness 0.05
A piece of washi paper (mm) was placed on the inner bottom surface of the lower mold as shown in Figure 4, and a polypropylene resin containing 40% mica was extruded from the nozzle of the extruder on top of it to a pressure of 220 as shown in Figure 5! 7/cm (mold clamping force 50T), pressure molded at a mold temperature of 30 degrees and cooled (20
sec) It was solidified to obtain an integrally molded product. When the peel strength between the resin and Japanese paper of this product was measured, a value of 420111/C- was obtained.

Example 2 Length 230a+m, ll98+u and M [length 0.05gv
(D Washi was fed onto a conveyor belt, and while being moved intermittently, 40 sheets of Japanese paper were plasticized by an extruder from a certain point.
% of mica-containing polypropylene resin was placed thereon, and then the sheets were transferred one by one onto the open lower mold, the upper mold was closed, and pressure molded (pressure: 220 ko/cm2 (molding mold clamping force: 50
=T), mold temperature 30'C)L, and was cooled and solidified to obtain an integrally molded product.

The peel strength between the resin and Japanese paper of this product was 480 o/cm.

(c) Effects of the invention By adopting the configuration described above, the present invention has the following effects:
Of course, the synthetic resin permeates into the fibrous sheet and provides a strong bond, but unlike injection molding, it is difficult to pressurize paper or cloth, which has relatively low strength and rigidity. Since the resin has a weak flowing force, it has the advantage of being less likely to tear or wrinkle.

In addition, regarding the invention of a method for placing synthetic resin on a $111 sheet and then bringing it into the mold, operations outside the mold can be carried out in parallel to the cooling and solidification of the synthetic resin inside the mold. Molding time can be shortened, and there is no need to increase the number of molds.

By obtaining this kind of synthetic resin product in which the fibrous sheet is firmly joined, it is also easier to use the surface of the fibrous sheet to join other sheets, etc., which was difficult to join in the past. It is also extremely useful.

[Brief explanation of the drawing]

Fig. 1 is a perspective view showing an integrally molded product according to the present invention; Fig. 2 is a perspective view showing a conventional molded product; Figs. FIG. 3 shows the state in which the van quality sheet is placed on the mold (lower mold) before mold clamping, and FIG. 4 shows the step of further placing synthetic resin thereon. Figure 5 is a cross-sectional view showing the state during mold clamping, Figures 6 and 7 are process diagrams showing the supply of synthetic resin to the mold, Figure 6 is during supply, and Figure 7 is during supply. FIG. 8 is a cross-sectional view showing the subsequent state. FIG. 8 is a diagram showing an example of a case where synthetic resin is supplied outside the mold. 1... Synthetic m1L2-... Fibrous sheet, 3... Adhesive, 4... Mold (4a... Upper mold, 4b... Lower mold), 5... Extruder, 6 ···belt conveyor.

Claims (2)

[Claims] (1) Integration of a synthetic resin and a fibrous sheet characterized by placing a plasticized synthetic resin on a fibrous sheet placed in advance in a lower mold, closing the upper mold, and press-molding. Molding method. (2) A method of integrally molding a synthetic resin and a fibrous sheet, which is characterized by placing a plasticized synthetic resin on the fibrous sheet, placing it in a lower mold, closing the upper mold, and performing pressure molding. .