JP2779700B2 - Plate-like foam and method for producing the same - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Industrial Application Field] The present invention relates to a plate-like foam and a method for producing the same. More specifically, the present invention relates to a method in which a base resin impregnated with a foaming agent is foamed when thermoplasticized. TECHNICAL FIELD The present invention relates to a method for producing a foam-like foam and a plate-like foam produced by the method.

[Conventional technology and its problems]

In general, a method for producing a foam of a thermoplastic resin mainly includes a method of decomposing by heating to generate a gas or a method of decomposing by a chemical reaction to generate a gas, that is, a method of blending a so-called blowing agent to generate a gas. For example, a method of forcibly mixing an inert gas such as carbon dioxide, nitrogen, and air with a plasticized resin, or a method of mixing a volatile substance with the resin and foaming the mixture by heating is performed. .

By the way, the thermoplastic resin foam produced by such a method is used as a finished product or an intermediate product (requiring secondary molding) in a foamed state, and is characterized by its light weight, heat insulating properties, and shock absorbing properties. Although it has excellent sound absorption properties, it has poor mechanical strength. Therefore, various proposals have been made for the purpose of improving the strength.

For example, after a foaming agent such as propane, butane, pental, or foreon is pressed into an extruder and dissolved and absorbed in a base resin, when extruding from the extruder, a die attached to a tip of the extruder melts. A comb-shaped resistor is provided at the exit of the resin passage, and the molten resin is foamed while flowing out along the comb-shaped resistor, so that the foaming is performed coarsely and densely. A proposal for obtaining a certain plate-like foam has been made (see Japanese Patent Publication No. 47-8950).

By the way, according to the extruder using such a comb-shaped resistor, it is possible to produce a plate-like foam in which the upper and lower surfaces are made of a skin (skin layer) composed of extremely fine cells, and the inside thereof has a rough and dense structure. However, there is a problem that such a plate-like foam cannot obtain strength as high as a foamable composite plate having a laminated structure.

[Means for solving the problem]

Therefore, the present invention was created to solve such a problem, and the gist of the present invention is that (1) one surface of a synthetic resin plate-like foam is in a non-foamed state and the other surface is in a foamed state. And (2) one of the plate-like base resin, which is formed from a foam in which the expansion ratio is sequentially changed in accordance with the thickness direction of the other one of these. After sticking the foaming agent impregnation preventing member on the surface, the plate-shaped base resin is left in a volatile foaming agent atmosphere gas in a closed container, and impregnated with the foaming agent only from one side, The method for producing a plate-like foam is characterized in that, when the thermoplastic resin is taken out and thermoplasticized, the foam is foamed so that the expansion ratio varies from the one surface to the other surface in the thickness direction.

〔Example〕

The configuration of the present invention will be described in detail based on the manufacturing apparatus shown in the accompanying drawings.

FIG. 1 is a cross-sectional view of a plate-like foam of the present invention, FIG. 2 is a cross-sectional view of an impregnation apparatus for carrying out the production method of the present invention, and FIG.
Fig. 4 is a cross-sectional view of another impregnating device, Fig. 4 is a cross-sectional view of Fig. 3 as viewed from b to arrow, Fig. 5 is a cross-sectional view of still another impregnating device, and Fig. 6 is a thickness direction of the plate-like foam. 4 is a graph of the content of a foaming agent with respect to the weight of the foaming agent.

The plate-like foam 1 according to the present invention is one in which one surface is in a non-foamed state and the other surface is in a foamed state, and the expansion ratio is sequentially changed in accordance with the thickness direction of the plate (thus also referred to as inclined foaming). ), The resin is hard and has high strength on the non-foamed side 2 and is soft and has heat insulating property, sound absorbing property and shock absorbing property on the foamed side 3 even though it is a homogeneous resin. Of course, a skin layer is formed on the skin on the foam side 3.

In order to manufacture such a plate-like foam 1, the plate-like base resin 4 is molded with, for example, polyetherimide, polycarbonate, or polyetheretherketone.

This plate-shaped base resin 4 is put in a closed container 5 at normal pressure as shown in FIG. 2 and impregnated with a volatile foaming agent 6. ,
Methylene chloride) 6, and a perforated plate 7 such as a wire mesh is horizontally provided above the methylene chloride) 6. Then, on the porous plate 7, the plate-shaped base resin 4 on which a foaming agent impregnating prevention film (metal plate or resin film) 8 is stuck only on the upper surface or the lower surface is placed. In FIG. 2, 4, 7, and 8 are exploded views separated from each other, but they are closely attached. If the plate-shaped base resin 4 is left for several hours in the blowing agent atmosphere gas 6a generated by the evaporation of the foaming agent 6, the foaming agent 6 is impregnated into the plate-shaped base resin 4 from one side thereof. Go being.

Next, the foaming agent impregnation prevention film 8 is peeled off, and the plate-like base resin impregnated with the foaming material 6 (this is referred to as a plate-like foam material 9) is prevented from being abnormally foamed by a hot press or an autoclave. The above-mentioned plate-like foam 1 is obtained by thermoplasticizing at about 190 ° C. while applying a slight pressure.

Analysis of the plate-like foam material 9 showed that the foaming agent content in the plate thickness direction was as shown in the graph of FIG. That is, FIG. 6 shows the foaming agent content on the vertical axis and the plate thickness direction on the horizontal axis. As is clear from FIG. 6, the foaming agent content is changed from the foaming side 3 to the non-foaming side 2. The amount was gradually decreasing.

Next, as shown in FIGS. 3 and 4, another impregnation device for producing the plate-like foam 1 of the present invention will be described.
With this impregnating device, a long roll-shaped plate-shaped foam material 9 can be manufactured. That is, the closed container 5 is provided with an inlet 10a formed by a pair of sealing rollers 10, 10 and an outlet 11a formed by a pair of sealing rollers 11, 11. An endless conveyor belt 12 is provided which moves from 10a to an outlet 11a and slowly circulates outside the container.
Since the wound plate-shaped base resin 4 is placed on the endless conveyor belt 12 while being unwound and passes through the closed container 5, the volatile foaming agent 6 is not impregnated from the placement surface thereof,
Plate-like foam material 9 impregnated from the opposite mounting surface (upper surface)
Is formed. When the plate-like foam material 9 is wound as it is, the materials adhere to each other or the foaming agent 6 is lost due to volatilization. Instead, these sealing materials 13 are attached to the upper and lower surfaces of the plate-shaped foam material 9 and wound. Of course, when the plate-like foam material 9 is thermoplasticized to form the plate-like foam 1, the sealing material 13 is stripped in advance. In addition,
In the figure, reference numeral 14 denotes a support roller.

Next, referring to FIG. 5, which shows a modification of the impregnating device shown in FIG.
Is provided, and a separate foaming agent storage container 15 is provided so that only the foaming agent atmosphere gas 6a is supplied to the closed container 5. In this way, the content of the foaming agent 6 can be controlled together with the traveling speed of the endless belt conveyor 12 by controlling the concentration and the convection speed of the foaming agent atmosphere gas 6a.

〔The invention's effect〕

According to the present invention, since the expansion ratio is changed according to the thickness direction from one foaming surface of the plate-like foam to the other non-foaming surface, the plate-like foam and the ordinary resin plate are laminated. The same strength as that of the foam composite board can be obtained, and not only the flexural strength of the foam but also other tensile strength and the like can be improved. Moreover, since there is no need to bond the foam and the non-foam, there is no need to worry about peeling.

Further, it can be used as a material that is hard and requires strength on one side and soft on the other side and requires heat insulation, sound absorption, shock absorption, and the like.

In addition, since a single plate-shaped base resin impregnated with a foaming agent is obtained, a foam can be formed at the time of thermoplasticization, and therefore, another reinforcing fiber (eg, glass fiber) is impregnated with the resin in advance. It can be used to form a composite material in which laminated prepreg sheets are laminated.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a plate-like foam of the present invention, FIG. 2 is a cross-sectional view of an impregnating apparatus for carrying out the production method of the present invention, FIG. 3 is a cross-sectional view of another impregnating apparatus, FIG. Fig. 3 is a cross-sectional view taken along line b-f in Fig. 3, Fig. 5 is a cross-sectional view of still another impregnating device, and Fig. 6 is a graph of the foaming agent content in the thickness direction of the plate-like foam. 1 ... plate-like foam, 2 ... non-foamed side, 3 ... foamed side, 5 ...
... airtight container, 6 ... volatile foaming agent.

Continuation of the front page (58) Field surveyed (Int.Cl. ⁶ , DB name) B29C 67/20 B29C 44/00-44/60 C08J 9/00-9/42 B32B 1/00-35/00

Claims (2)

(57) [Claims] 1. One side of a synthetic resin plate-like foam is in a non-foamed state, the other side is in a foamed state, and the expansion ratio is sequentially changed from one of these to the other in the thickness direction. A plate-like foam formed of a foam. 2. After adhering a foaming agent impregnation preventing member to one surface of the plate-like base resin, the plate-like base resin is left in a volatile foaming agent atmosphere gas in a closed container, After impregnating the foaming agent from only one side, when taking out and thermoplasticizing, foaming is performed so that the foaming ratio varies depending on the thickness direction of the other side from the one side. A method for producing a plate-like foam.