JPH04136045A - Method for manufacturing polystyrene resin foam - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

[Detailed Description of the Invention] (Industrial Application Field) A method for extruding and foaming polystyrene resin using non-explosion breath and water as a foaming agent, in particular, without resin build-up in the tip slit of the extrusion mold. , relates to a method for producing a polystyrene resin foam having finer cells.

(Prior Art and Problems to be Solved) Attempts have been made to extrude and foam polystyrene resins using water as a foaming agent.

In this case, there is a method in which water, which is a foaming agent, is mixed with polystyrene resin pellets in advance and then supplied to an extruder, or
Attempts have been made to feed water directly into the extruder hopper.

When water and polystyrene resin pellets are mixed as a blowing agent and fed to an extruder, the viscosity of the molten resin composition becomes low during the extruder's extrusion process, resulting in a so-called "slip" phenomenon, causing the resin to slip off the extruder screw. The expansion ratio of the resulting foam varies because the penetration of the foam varies.

For this reason, the above-mentioned problem is solved by directly adding water from the middle of the extruder.

Recently, a method has been proposed in which a super absorbent resin absorbs water to form a gel, which is mixed with a polystyrene resin, and then fed to an extruder for extrusion foaming.

However, when water is used as a foaming agent, the foaming ratio does not increase, and the foam tends to have large cells and non-uniform cells. Therefore, soda carbonate or bicarbonate soda (baking soda) is added along with water as a foaming agent.
They are mixed and foamed, but in this case, if the operation is continuous, the resin will build up in the slit at the tip of the extrusion mold, deteriorating the appearance of the foam.

Furthermore, since the gel-like superabsorbent resin that has absorbed water is in a dry state, it has poor miscibility with polystyrene resin and has the disadvantage that a uniform foam cannot be obtained.

The present inventor has completed the present invention as a result of various studies to improve the above-mentioned drawbacks and produce a uniform polystyrene resin foam using water as a blowing agent. Provided is a method for producing a polystyrene resin foam having good fine cells using water as an agent.

(Means for Solving the Problems) The gist of the present invention is to provide a method for manufacturing a polystyrene resin foam by extruding and foaming a polystyrene resin using an extruder, in which fine particles of silica, alumina, etc. are uniformly dispersed in water. Polystyrene resin foaming characterized in that a superabsorbent resin absorbs a suspension (sol) to form a gel-like mixture, and then the gel-like mixture is mixed with a polystyrene resin, followed by extrusion foaming. It is a method of manufacturing the body.

That is, in the present invention, a suspension (sol) in which inorganic fine particles such as silica and alumina are uniformly dispersed in water is absorbed into a superabsorbent resin to form a gel-like mixture, thereby reducing friction due to the attached fine particles. The coefficient increases and the adhesion improves.

Therefore, when mixed with a polystyrene resin, the adhesion to the resin is improved, and a uniform foam can be produced without causing slippage in the extruder.

Further, the present invention will be described in detail.

The fine particles used in the present invention are inorganic fine particles such as alumina and silica, but preferably alumina or silica, and the finer the particle size of these, the better, usually 0.5 to 2
It is about 0 micron. When dispersing these fine particles in water, a surfactant (dispersant) or alcohol can be added. The concentration of fine particles in this sol is 20 to 40%, but particles with a concentration of 20% or less can also be used by further diluting with water.

The superabsorbent resin that can be used in the present invention is crosslinked polyacrylic acid, acrylic acid/acrylic acid ester copolymer resin, etc., and the amount used is 3 to 10% in the sol. Moreover, this super absorbent resin has lo.

Preferably, it is finer than a mesh. The reason for this is that the superabsorbent resin does not melt in the extruder, so if the particles are large, they tend to clog the extruder screen or the tip slit of the extrusion mold, resulting in poor appearance of the resulting foam.

The superabsorbent resin that has absorbed the sol takes on a gel-like appearance.

The amount of the gel-like material added to the polystyrene resin is 5 to 20%.

The polystyrene resin pellets and gel are mixed in a Henschel mixer.

Next, the present invention will be described in more detail with reference to Examples.

Example】 A polystyrene compound is manufactured with the following blending ratio.

Polystyrene resin (Ml: 3) pellets 100 parts by weight Super absorbent resin (Aquamate AQ-1oo) 1 part by weight Silica gel (Snowtex [F] with 20% silica content)
100 parts by weight of water 100 parts by weight First, 100 parts by weight of Snowtex 0 with a silica content of 20% is suspended in 100 parts by weight of water to obtain a 10% concentration silica sol, and then 1 part by weight of a super absorbent resin is added to 15 parts by weight of this silica sol. to form a gel-like mixture.

16 parts by weight of the obtained silica gel mixture and 100 parts by weight of polystine resin are mixed in a Henschel mixer.

Next, this polystine resin is supplied to an extruder hopper to perform extrusion foaming.

The extruder used was a 40φ single screw extruder (L/D 25).
The mold was a rod type with a diameter of 3M. The operating temperature of the extruder was 150°C-180°C, the rotation speed was 55 rpm, and the output was 8 kg/H.

The foaming ratio of the obtained diameter 91ul T1 foam was 15 times,
The bubbles were uniform.

(effect) The present invention has the following effects.

(1) By absorbing the silica sol into the superabsorbent resin, a uniform mixture was obtained that adhered to the polystyrene pellets, stabilizing the penetration of the extruder, and eliminating variations in the foam.

(2) Fine particles of silica, alumina, etc. contained in the suspension serve as a foam nucleating agent when released as a foam from an extrusion die, resulting in a foam in which fine air bubbles are uniformly dispersed.

(3) It is inexpensive because the foam can be obtained using a normal extruder.

(4) The build-up phenomenon at the mold tip was eliminated.

Claims (1)

[Claims] 1. A method for producing a polystyrene resin foam by extruding and foaming a polystyrene resin using an extruder,
A suspension (sol) in which fine particles of silica, alumina, etc. are uniformly dispersed in water is absorbed into a super absorbent resin to form a gel-like mixture, and then the gel-like mixture is mixed with a polystyrene resin. , a method for producing a polystyrene resin foam characterized by extrusion foaming. 2. The method for producing a polystyrene resin foam according to claim 1, wherein azodicarbonamide is added during extrusion foaming.