JPH02272040A - Production of expansion molded body - Google Patents

Abstract

PURPOSE:To obtain an expansion molded body for electromagnetic wave absorbers in a large amount at a low cost without requiring a pulverizer by mixing preexpanded beads with graphite, an adhesive, etc., and drying the preexpanded beads in a hot air blower while nearly homogeneously applying the graphite to peripheral surfaces of the preexpanded beads. CONSTITUTION:The objective expansion molded body obtained by drying preexpanded beads using a hot air blower while mixing the preexpanded beads with graphite and an adhesive and molding each preexpanded bead having a graphite layer nearly homogeneously applied to the peripheral surface thereof into a desired shape. Since the hot air is circulated with the hot air blower to dry the preexpanded beads, the hot air sufficiently flows between the respective beads and each preexpanded bead can be directly dried without forming the beads into a block form.

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a method for manufacturing a foamed molded article, and particularly to a method for manufacturing a radio wave absorber made of a polystyrene resin foam or the like.

[Prior Art] Conventionally, as shown in FIG. 2, a method for manufacturing this type of radio wave absorber involves thoroughly foaming aged foamed beads, such as polystyrene foamed beads, after pre-foaming (secondary foaming). Kneading 3
Mix 4 graphite, vinyl acetate, flame retardant, etc. to uniformly adhere a graphite layer to the circumferential surface of the foamed beads, then transfer the tray to tray S and dry it in a dryer 6 to form foam. A bead block body 7 is formed, and the block body is crushed into individual foam beads by a crusher 8,
The foamed beads were structured and molded into a desired shape 10 when necessary.

[Problems to be Solved by the Invention] In the above manufacturing process, the foamed beads, graphite, adhesive, etc. are sufficiently mixed to adhere the graphite layer around the foamed beads, and then the excess adhesive is dried. For this reason, they are dried by blowing hot air onto them, but because the foam beads are lightweight, it is not possible to blow hot air directly onto them, so it is necessary to transfer them to a tray and dry them inside a housing (dryer). The block-shaped foamed beads dried in the dryer were then crushed in a pulverizer to produce individual foamed beads.

However, this method not only requires the time and effort of transferring from the mixer to the tray and from the mill to the pulverizer, but also requires the time and effort of drying the foam beads in the form of a block and using the pulverizer to break them down one by one. It was expensive and unsuitable for mass production.

SUMMARY OF THE INVENTION Therefore, an object of the present invention is to provide an innovative method for producing a foamed molded product that does not require the effort of transferring the product to a tray and that requires fewer steps than the above steps.

[Means for Solving the Problems] In order to achieve the above object, the method for producing a foamed molded article according to the present invention involves mixing pre-foamed foamed beads with graphite, an adhesive, etc. in a mixer, and forming the foamed beads. This method dries the graphite layer by blowing hot air from a hot air blower while adhering the graphite layer substantially uniformly to the circumferential surface.

[Function] As mentioned above, during the process of mixing the pre-foamed foamed beads, graphite, and adhesive, hot air is circulated by a hot air machine for drying, so that sufficient hot air flows between each foamed bead. Unlike the conventional method, the foamed beads do not become block-shaped (-- They are dried as individual foamed beads. Therefore, there is no need for a process using a crusher as in the conventional method.

Also, there is no need to transfer the product from the mixer to the tray or from the dryer to the pulverizer.

Each foamed bead obtained by the above method is molded into a desired shape to obtain a foamed molded product, for example, a radio wave absorber, as in the conventional method.

[Example] Embodiments of the present invention will be described below based on the drawings.

FIG. 1 is a process diagram showing one embodiment of the method for manufacturing a foamed molded body of the present invention, and illustrates a method for manufacturing a radio wave absorber using a polystyrene resin foam.

In this figure, polystyrene foam beads are pre-foamed,
While aging 2, the graphite, adhesive, vinyl acetate, flame retardant, etc., which have been sufficiently kneaded 3, are put into a mixer after mixing 3 and thoroughly mixed 4. Through this step, a graphite layer is deposited substantially uniformly on the circumferential surface of the polystyrene foam beads.

Next, during this mixing process, hot air is sent by a dryer 11 installed on the side of the mixer and communicated with the inside of the mixer. This hot air is preferably circulated within the mixer to ensure that all the foam beads are covered with hot air.

By this process, the polystyrene foam beads are dried before being fixed into a block shape, and the graphite layer is dried with the graphite layer adhered substantially uniformly to each peripheral surface.

These foamed beads are kept in stock 9 as required as in the past, and molded into a desired shape 10 when necessary.

Note that the same reference numerals as in the diagram of the conventional example described above (FIG. 2) indicate the same or corresponding parts.

Further, although polystyrene resin foam is exemplified in this embodiment, the material is not limited to this, and polyethylene, polypropylene, polyvinyl chloride, polyurethane, etc., or copolymers thereof may also be used. Moreover, it is applicable not only to the production of radio wave absorbers but also to the production of other foam molded products.

[Effects of the Invention] The present invention comprises a process of mixing conventional foam beads with graphite, vinyl acetate, flame retardants, etc., a process of putting the mixture in a tray and drying it in a dryer, and a process of pulverizing the dried block. The process of crushing each foam bead using a machine,
Since the process of mixing the foamed beads, graphite, vinyl acetate, flame retardant, etc., is combined into one process by blowing hot air with a dryer, the manufacturing time can be significantly shortened.

In addition, we were able to eliminate the conventional process of crushing blocks of foam beads into individual foam beads, transferring the process from the mixer to the dryer using a tray, and the process of transferring from the dryer to the crusher. This made it possible to produce continuously.

Conventionally, it was not possible to increase the capacity of the mixer due to the need for quick transfer from the mixer to the tray, but the manufacturing method of the present invention eliminates the need for each transfer step. Therefore, a large mixer can be used and mass production becomes possible.This has the effect of reducing production costs.

[Brief explanation of drawings]

FIG. 1 is a process diagram showing an embodiment of the method for manufacturing a foamed molded article of the present invention, and FIG. 2 is a conventional process diagram. 1...Pre-foaming, 2...Aging, 3...Kneading,
4...Mixing, 5...Tray, 6.
...Dryer, 7...Block body, 8...Crusher,
9... Stock, 10... Molding, 11... Dryer. Diagram

Claims (1)

[Claims] (1) Pre-foamed foamed beads, graphite, and adhesive are mixed and dried with hot air from a hot air blower to form individual foamed beads with a graphite layer approximately uniformly attached to the surrounding surface of the foamed beads. A method for producing a foam molded article, the method comprising: obtaining a foam molded article by molding into the shape of.