JPH0119333B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for differently forming an olefinic resin foam sheet (hereinafter simply referred to as a foam sheet).

Conventionally, various methods such as vacuum forming and press molding have been proposed for forming foam sheets such as polyethylene foam sheets and polypropylene foam sheets into different shapes. The method used is to heat the material to a softening temperature, that is, to the plastic deformation temperature, apply tension, apply external force with a metal mold, wooden mold, etc. to form the desired shape, and then cool it.

However, in these methods, the temperature range suitable for forming a modified mold is narrow near the plastic deformation temperature, as shown as region A in FIG. 1, and therefore it is difficult to control equipment and manage product characteristics.

That is, the elongation and tensile strength of a foamed sheet are significantly lower near its plastic deformation temperature than at room temperature. Furthermore, since the slipperiness is poor, there is a problem that the foam sheet breaks during molding.

Furthermore, near the plastic deformation temperature, the drawing depth of the foam sheet, which is proportional to the elongation rate, or the critical deformation rate, decreases, so it is difficult to give the foam sheet a significantly different shape. The difference in thickness between the flat part and the flat part becomes very large, complicating the insulation design and buffer design.

The present invention has been made in order to solve the problems of the conventional method, and the foam sheet does not break during the irregular forming process, the entire thickness of the irregularly formed foam sheet becomes almost uniform, and furthermore, deep drawing is possible. The object of the present invention is to provide a method for molding a foamed olefin resin sheet.

That is, the present invention elastically deforms a polyolefin resin foam sheet into a desired shape at a temperature of 0°C to 80°C, then heats the foamed sheet to the plastic deformation temperature while maintaining this elastically deformed state, and then cools it. This is a method for differently forming olefin resin foam sheets.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The details of the present invention will be described below with reference to an embodiment shown in the drawings.

FIG. 2 is a process diagram of an embodiment of the method of the present invention.

In this example, the polyethylene foam sheet was heated at 0°C, such as a polypropylene foam sheet.
At a temperature of ~80° C., it is inserted between, for example, a convex mold 2 and a concave mold 3 and held horizontally (FIG. 2a). The upper and lower molds 2 and 3 are pressed to elastically deform the foamed sheet 1 into the shape of a mold cavity (FIG. 2b).

Next, heat molding is performed by heating the foam sheet 1 to a plastic deformation temperature, for example, 110 to 180°C, while keeping the temporary molds 2 and 3 pressed against the foam sheet 1, to shape the foam sheet 1. (Figure 2c).

After that, the stable curing temperature of the foam sheet 1 is reached.
Cool to around 20°C to obtain a molded product (Figure 2 d).
Since the foam sheet 1 is heated and molded while maintaining its elastic deformation state, recovery of the bubbles in the foam sheet 1 can be observed during molding, and it is possible to obtain a well-balanced irregularly shaped molded product with little settling or difference in thickness. Can be done.

In this way, the foam sheet that has been given a different shape mold by the method of the present invention has a difference in local thickness of ±50% compared to the foam sheet that has been given a different shape mold by the conventional method.
%, but the difference remained within ±10%.

Furthermore, in the process of heating the foam sheet,
The air bubbles inside the foam sheet, which had been reduced during the temporary molding process, increased again, making it possible to obtain a foam sheet that did not sag.

As explained above, according to the method of differently forming an olefin resin foam sheet according to the present invention, the elongation rate, tensile strength, and slipperiness of the foam sheet are high at 0°C.
By subjecting the foam sheet to elastic deformation at a temperature of ~80°C, deep drawing can be performed without causing local thickness differences in the foam sheet and without cutting the foam sheet. In addition, it is easy to control equipment and manage product characteristics, and the risk of producing defective products is low, so the thickness of the foam sheet to be subjected to irregular molding can be minimized. Therefore, it is also possible to reduce costs.

[Brief explanation of drawings]

FIG. 1 is a graph showing temperature-elongation and tensile strength of a foamed sheet, and FIG. 2 is a process diagram of an embodiment of the method of the present invention. 1...Polyolefin resin foam sheet, 2...
... Convex type, 3... Concave type.

Claims (1)

[Claims] 1 Polyolefin resin foam sheet at 0℃~
A method for molding an olefin-based resin foam sheet into a different shape, characterized by elastically deforming it into a desired shape at a temperature of 80°C, then heating the foam sheet to a plastic deformation temperature while maintaining this elastic deformation state, and then cooling it. .