JPH03200848A - Production of molded composite foam - Google Patents

Abstract

PURPOSE:To produce the title foam sufficiently crushed in all parts by placing a hollow frame having many small holes and an air-injecting hole in a mold, molding a foam integrally with the frame in the mold, and then blowing a compressed air into the foam through the small holes to break closed cells in the foam. CONSTITUTION:A hollow frame 13 having many small holes 14 and an air- injecting hole 15 is placed in a mold for molding, e.g. a set pad 11, and a foam, e.g. a polyurethane foam is molded integrally with the frame 13 in the mold. Then, a compressed air is injected into the frame 13 through the air-injecting hole 15, and is diffused through the small holes 14 in the foam to break closed cells contained in the foam, thus giving the title foam.

Description

Detailed Description of the Invention [Industrial Field of Application] The present invention is directed to the production of so-called integrally foamed synthetic resin products in which a hollow frame is embedded as an insert and integrally foamed. The present invention relates to a method for bursting bubbles.

[Conventional technology]

As described in Japanese Utility Model Application Publication No. 62-55426, closed cells contained in a foam molded product such as flexible polyurethane foam are crushed to prevent deformation such as shrinkage, and to reduce hardness and In order to improve properties such as cushioning properties, the foamed molded product is passed through a pair or more of rolls to compress it to about 30% of its original thickness, bursting the closed cells and converting them into open cells. The method of doing this has been conventionally used.

In the case of car seat (chair) pads, urethane sheets are foam-molded from above and below using a large number of rolls 1 arranged in stages as shown in Figure 5, in order to improve riding comfort or prevent deformation. The pad 2 is compressed to crush the open cells, but recently, in order to improve the quality after covering and to automate the covering, as shown in Figure 6, the open cells are crushed. Since then, the so-called integrated foam molding method, in which the frame 3 etc. are embedded as an insert and foamed as an integral part, has become commonplace.In order to improve the riding comfort of such seats and prevent deformation, When crushing pads, if the compression method using rolls 1 as shown in Fig. 5 is used, if the interframe dimension a is larger than the minimum thickness dimension, the frame 3 will become an obstacle and the sheet will become thinner. Crushing of part 4 etc. is not possible. If you force it, there is a risk that the inserted frame 3 will be bent or crushed by the rolls 1 and deformed. Therefore, in the prior art described above, the surroundings of the crushing rolls are covered with a cushioning material, and the frame 3 is This prevents strong forces from acting against it.

[Problem to be solved by the invention]

In the above-mentioned conventional technology, the rolls are covered with a cushioning material, so the tightness is generally weak, and closed cells in the molded product between the frames are difficult to crush. Air bubbles may remain, which may cause the molded product to deform into an irregular shape later on, or prevent it from exhibiting its cushioning properties to the fullest.On the other hand, if you tighten it too tightly, the surface of the roll will be coated with cushioning material. Even if it is, the inserted frame will be damaged or deformed.

An object of the present invention is to address these problems of the prior art and to develop a simple crushing method that can thoroughly crush every corner of a foam molded product without the risk of deforming the frame. do.

[Means to solve the problem]

As a means to solve the above problems, the present invention performs integral foam molding of synthetic resin by placing a hollow frame having a large number of small diameter holes and at least one air pressure inlet in a mold. After molding, compressed air is supplied into the hollow frame from the air pressure inlet and the compressed air is diffused into the molded product through the large number of small diameter holes, thereby bursting the closed cells contained in the molded product. A method for manufacturing an integrally foamed molded product is provided.

[For production]

A hollow frame with a pneumatic inlet and numerous small-diameter holes is placed in a mold, and then a foamable resin raw material is injected into the mold to form a one-piece foam mold. The foamed resin embeds the hollow frame and adheres to its surface, forming an integral foamed molded product.

Compressed air is supplied to the pneumatic inlet of the hollow frame after the molding is completed and before or after the molded product is removed from the mold. The compressed air travels through the hollow frame over the entire area of the foam molding, exits through a number of small diameter holes, and penetrates and diffuses through the foam resin layer of the molding. In areas where the cells are open, air diffuses through the communication parts between the cells with relatively little resistance, but when it hits a closed cell, the closed cell is compressed and crushed, or the walls of the cell are compared. Breaks through the thin weak point of the target and connects the bubbles.

In this way, by the time the compressed air reaches the outer surface of the molded article, the closed cells are ruptured from the inside, and the entire molded article becomes open cells.

〔Example〕

FIG. 1 shows an example of a seat pad 110 that has been integrally molded, which is an object of the present invention, and a hollow frame 13 is initially inserted into the soft polyurethane foam 12 during integrally foaming. It is embedded from. Since urethane resin has strong adhesive strength, the urethane foam is strongly adhered to and integrated with the surface of the frame 13. A large number of small-diameter holes 14 are pre-drilled in the hollow frame 13, and a pneumatic inlet 1 is provided in a part of the hollow frame 13.
A relatively large-diameter hole 5 is provided, and a temporary cover is applied to this hole during the integral molding process to prevent the urethane raw material from flowing into the frame 13. Needless to say, this temporary lid may be formed in the form of a protrusion on the mold. In this case, the urethane foam 12 may be removed by a temporary cover only at the air pressure inlet 15 of the hollow frame 13, and the air pressure inlet 15 may be opened to the outside by removing the temporary cover, or the temporary cover may be made of adhesive. Simply cover the air pressure inlet 15 with something like tape, and then close the seat pad 1.
After molding the urethane foam 12, a small incision may be made in the portion of the air pressure inlet 15 so that the air pressure inlet 15 can be opened to the outside.

FIG. 2 shows a cross section taken along the line ■--■ in FIG. 1. In this example, after the integral molding of the seat pad 11 is completed, it is taken out from the mold and the hollow frame 13 is removed from the mold.
An air nozzle 16 is connected to the air pressure inlet 15 of the air pressure inlet 15 as shown by the broken line, and high-pressure compressed air is injected to gently and strongly pressurize the air nozzle 16. The injected compressed air travels through the hollow frame 13, exits through a large number of small diameter holes 14 throughout the seat pad 11, enters the urethane foam 12, ruptures the weak part of the wall of the closed cells, and causes the air bubbles to collapse. It diffuses while communicating with the air, reaches the outer surface, and escapes into the atmosphere. In this way, the urethane foam 12 can be easily crushed simply by introducing compressed air into the hollow frame 13 without applying mechanical pressure using rolls or the like. However, this does not preclude the use of this method in combination with crushing of the thick wall portion using rolls.

FIG. 3 shows another embodiment. In this example, after the seat pad 11 is molded in the mold 17,
Crushing is performed before taking it out.

For this purpose, the mold 17 is provided with a socket 18 that receives the air pressure nozzle 16, and this socket 18 communicates with the air pressure inlet 15 of the hollow frame 13, which is an insert placed in the mold. It has a hole 19. In this example, the mold 17 consists of an upper mold 17a and a lower mold 17b, and the socket 18 of the air injection nozzle is provided in the center of the upper mold 17a. That's fine. If crushing is performed with the seat pad 11 in the mold 17, it will be difficult for the compressed air to escape, but the crushing success rate tends to be somewhat improved. When the crushing is finished, the back pressure increases, so the work ends there.

In yet another embodiment shown in FIG. 4, compressed air nipples 20 are formed in advance at the corners of the hollow frame 13, and before the seat pad 11 is taken out from the mold.
Alternatively, after taking it out, the compressed air connector 21 is connected to the nipple 20 to feed compressed air into the hollow frame 13. In this case, the nipple 20 is provided so as to communicate within the hollow frame 13, so that the nipple 20 acts as an air pressure inlet.

〔Effect of the invention〕

By the method of the present invention, closed cells in the foamed resin of an integrally foamed molded product with a hollow frame inserted are easily bursted into open cells, improving flexibility and cushioning properties and preventing deformation. be able to. Since there is no need to use crutching rolls, the inserted frame will not be deformed by the rolls.
It has the advantage of being able to thoroughly crush areas that are difficult to crush with rolls, such as around the frame. Since crushing can also be performed within the mold, in this case the time is equivalent to omitting the crushing step, and work efficiency can be increased.

[Brief explanation of drawings]

FIG. 1 is a perspective view showing one embodiment of the present invention, and FIG. 2 is a perspective view showing one embodiment of the present invention.
■-■ cross-sectional view of the figure, FIG. 3 is a cross-sectional view showing another embodiment,
FIG. 4 is a perspective view showing still another embodiment, FIG. 5 is a conceptual diagram showing a conventional example, and FIG. 6 is a sectional view of a seat pad for explaining the problems of the conventional example. 1... Roll, 2... Seat pad,
3... Frame, 4... Thin wall portion, 11
...Seat pad, 12...Polyurethane foam, 13...Hollow frame, 14...Small diameter hole, 15
...Air pressure inlet, 16...Air nozzle, 17
...Mold, 18...Socket, 19...
Hole, 20...nipple, 21...connector. 1st Fig. 15...Pneumatic inlet 2 Fig. No. 20...Nipple No.

Claims (1)

[Claims] A hollow frame having a large number of small-diameter holes and at least one air pressure inlet is placed in a mold for integral foaming of synthetic resin, and after molding, compressed air is introduced into the hollow frame from the air pressure inlet. A method for manufacturing an integrally foamed molded article, characterized in that closed cells contained in the molded article are burst by supplying compressed air and diffusing the compressed air into the molded article through the large number of small-diameter holes.