JPH02196618A - Production of resin foamed sheet - Google Patents

Abstract

PURPOSE:To uniformly disperse bubbles and also to form a skin by molding expandable molten resin into a hollow body by extrusion and then press- contacting the resin expanded material of this hollow body and molding it into a solid sheet shape. CONSTITUTION:Expandable molten resin 1 is extruded by an extruder B. A core 5 is arranged in the inside of an extrusion die 4 and expandable molten resin 1 is foamed and molded into a hollow body by extrusion. In this case, stress caused by foaming of a foaming agent is exerted to both the outside and the hollow direction being the core 5 direction as shown in the arrows. Bubbles are uniformly dispersed and also a skin 3 is formed. Then this hollow resin expanded material 2 is passed through a land 6 and sent to a control head 7. Since the control head 7 is set at the temp. several tens degree lower than extrusion die 4, the hollow resin expanded material 2 is press-contacted and molded into a solid sheet shape and a resin foamed sheet A is produced.

Description

[Detailed description of the invention] [Industrial application field]

The present invention provides a resin foam sheet with evenly dispersed air bubbles! ! Concerning how to attend.

[Conventional technology]

Conventionally, foamed resin sheets have been manufactured by extrusion molding a foamable molten resin.

[Problem to be solved by the invention]

When the foamable molten resin 1 is extruded, the sheet-shaped resin foam 2 exiting the extrusion die 4 has expanded as shown in FIG. This is because outward stress is applied to the bubbles as shown by the arrows, which causes abnormal foaming, which not only prevents the bubbles from dispersing uniformly but also prevents the formation of a skin. Ta. The present invention has been made to solve the above problems, and its purpose is to produce a sugar beet foam sheet in which air bubbles are uniformly dispersed and a skin is also formed.

[Means for Solving the Problems 1] The method for producing a resin foam sheet of the present invention includes foamable melt resin I
The feature is that yIt1 is extruded into a hollow body shape, and then this hollow resin foam 2 is pressed and molded into a solid sheet shape, and this structure solves the above problems. be. [Effect 1] Since the foamable molten resin 1 is extruded into a hollow body shape, the stress generated by foaming is applied outward and in the hollow direction, and the air bubbles can be uniformly dispersed. Since the body 2 is pressed and formed into a solid sheet, a resin foam sheet A can be manufactured in which air bubbles are uniformly dispersed and an outer skin 3 is formed. [*Example 1 The foamable molten resin 1 used in the present invention is not particularly limited as long as it is a thermoplastic resin mixed with a blowing agent. For example, the thermoplastic resin may include vinyl chloride resin, polystyrene resin, etc. , ABS resin, low density, medium density,
Examples of blowing agents used alone or in combination include high-density polyethylene resin, polypropylene resin, copolymer resins of ethylene and propylene, vinyl acetate, methyl methacrylate, acrylic acid, etc. Fluoromethane, trichlorofluoromethane, propane, butane, or mixtures of these with methyl chloride, methylene chloride, pentane, hexane, etc., and chemically decomposed ones such as azocica-bonamide (ADCA) are used. In addition, additives such as a bubble control agent and various lubricants may be added as necessary. This foamable molten resin 1 is extruded by an extruder B. A core 5 is disposed inside the extrusion die 4, and the foamable molten resin 1 is foamed and extruded into a hollow body shape. In this case, as shown in FIG. 3, the stress generated by the foaming of the foaming agent is applied to the outside and the hollow direction, which is the direction of the core 5, as shown by the arrows, so that the bubbles are uniformly dispersed and the outer skin 3 is The formed hollow resin foam 2 is then sent to the control pad 7 via the land 6. The temperature of the control head 7 is set to several tens of degrees lower than that of the extrusion die 4. The hollow resin foam 2 is crimped by the mount roll 7 and molded into a solid sheet, thereby producing a resin foam sheet (A). The foaming ratio, that is, the density is adjusted by changing the temperature of the control pad 7 to iqv. For example, vinyl chloride resin 92.7% by weight, filler 5.0%
Weight%, pigment (titanium) 2% by weight, blowing agent (ADCA)
0.3% by weight is blended, and the temperature of extrusion die 4 is 180°C.
Extrusion molding is carried out at an extrusion speed of 600 to 900 AML and an expansion ratio (density) of 0.5 to 0.9. In this case, the temperature of the control controller 7 is 150 to about -20°C.
160"C. As a result, a vinyl chloride resin foam sheet A with an outer skin 3 formed thereon is obtained. [Effects of the Invention] In the present invention, a foamable molten resin is extruded into a hollow body shape. Then, this hollow resin foam is pressed and molded into a solid sheet, so the stress generated by foaming is applied outward and in the hollow direction, making it possible to uniformly disperse the air bubbles. Since this hollow resin foam is pressed and formed into a solid sheet, it is possible to manufacture a resin foam sheet in which air bubbles are uniformly dispersed and an outer skin is formed.

[Brief explanation of the drawing]

Figure 1 is a schematic sectional view showing the process of an embodiment of the present invention, Figure 2 is a sectional view taken along line X-X of Figure tIII1, Figure 3 is an explanatory view showing the same effect, and Figure 4 is a diagram showing the conventional example. 1 is a schematic cross-sectional view showing a foamed resin sheet, B is an extruder, 1 is a foamable molten resin, 2 is a resin foam, 3 is an outer skin, 4 is an extrusion die, and 5 is a schematic cross-sectional view.
is a core, 6 is a land, and 7 is a control head. Agent Patent Attorney Ishi 1) Ai 7th 2nd WJ Figure 3 Figure 4

Claims (2)

[Claims] (1) A method for producing a resin foam sheet, which comprises extruding and L-molding a foamable molten resin into a hollow body, and then press-bonding the hollow resin foam to form a solid sheet. (2) The method for producing a resin foam sheet according to claim 1, characterized in that the hollow resin foam is compressed at a temperature lower than the extrusion molding temperature.