JPH04108834A - Method for preparing molded product reclaimed from foamed polystyrene - Google Patents

Abstract

PURPOSE:To prepare a foamed polystyrene reclaimed product useful as a packaging material, insulating material, etc., by cutting a used foamed polystyrene molded product into fine pieces, leaving the fine pieces under a pressured gas to again impart foamability to the pieces, and subsequently molding the pieces. CONSTITUTION:(A) A used foamed polystyrene molded product is cut into 5mmX10mm cubes preferably by the use of heated wires such as nichrome wires without decomposing the foams thereof. (B) The cubes are left under a pressured gas preferably comprising air, nitrogen, a hydrocarbon, a fluoro compound or a mixture thereof and having a gauze pressure of 0.1-10kg/cm<2> to again impart foamability to the cubes, and the cubes are, if necessary, mixed with non-used preliminarily foamed polystyrene resin particles in an amount of 10-70vol.% based on the whole volume of the mixture. (C) The mixture is charged in a mold and molded to provide a reclaimed molded product.

Description

[Detailed Description of the Invention] (Industrial Application Field) The present invention relates to a method for manufacturing recycled foamed polystyrene molded products.
In particular, once used Styrofoam molded products are recycled.
This invention relates to a method for reusing packaging materials, insulation materials, etc.

(Prior Art) Generally, expanded styrene molded products are produced by heating expandable styrene resin particles with steam or the like to form pre-expanded styrene resin particles, which are then subjected to an aging process.

It is manufactured by filling a mold with small holes and reheating it to cause secondary foaming. The foamed polystyrene molded products thus obtained are used in many fields as packaging materials, building materials, food containers, etc. because they exhibit excellent economic efficiency, lightness, hygiene, heat insulation, etc.

However, styrofoam molded products have a low bulk density and are often used in one-way applications.

There were difficulties in disposing of it when it was discarded.

In view of these drawbacks, the entire purpose of the present invention is to effectively reuse a used expanded polystyrene molded product as a foam. More specifically, we cut used Styrofoam molded products into strips, use them as raw materials to give them foamability again, and then fill them into molds.

The idea is to mold it and use it as a styrofoam molded product.

There have been many attempts in the past to recycle used Styrofoam molded products. For example, JP-A-50-88
No. 185 and JP-A No. 50-88186, after a styrofoam molded product is cut into strips.

A method of obtaining expandable styrenic resin particles by re-impregnating the shrinkage 9 blowing agent with a blowing agent such as pentane is disclosed. Further, as a known technique, there is a method of crushing a foamed polystyrene molded product using a crusher, and then mixing and molding the molded product with foamed polystyrene particles for non-consumption use.

(Problem to be solved by the invention) However, these methods are difficult for the following reasons.

It was not done industrially. The former method was not economical because the styrofoam molded product was cut into strips and then filled into a pressure container (because it was a foam product, the volumetric efficiency was poor). On the other hand, in the method of mixing and molding foam particles after crushing them in a crusher, if the mixing ratio exceeds 10%, the cell structure of the 9 foam will be destroyed and the quality of the foamed polystyrene molded product will deteriorate significantly. It was not an appropriate treatment method.

The present invention solves these problems and provides an effective method for producing recycled foamed polystyrene molded products.

(Means for Solving the Problems) That is, 1. The present invention is a method for recycling a once-used polystyrene foam molded product, which involves first cutting the polystyrene foam molding into strips, and holding the strips under pressurized gas. The present invention relates to a method for producing a recycled polystyrene molded product, which is characterized in that the foamed polystyrene resin particles are mixed with unused pre-expanded styrene resin particles as needed, and then molded.

There are no particular limitations on the method of cutting a used Styrofoam molded product into small pieces, but there are also methods in which the cell structure of the closed-cell foam is destroyed using a crusher, etc. A method in which the cell structure is cut without destroying it using a hot wire is preferable from the viewpoint of the characteristics of the resulting recycled molded product.

The shape of the strip is not particularly limited.

It is best to have a uniform size, especially a cube (regular hexahedron)
, rectangular parallelepipeds, rectangular parallelepipeds, angular strips of shapes similar to these, etc. are preferred, and cubes are particularly preferred.

When mixing with unused pre-expanded styrene resin particles, the size of the pieces is compared to the particle size of the unused pre-expanded styrene resin particles.

Average particle diameter of styrene resin particles/size of #lI piece (diameter if spherical, average value of length, width, and height of 3 sides if angular) 0.01 to 1.0 It is preferable in terms of the appearance of the molded product and the ease of molding. The volume ratio of styrene resin particles/near fEU piece is preferably 10-6 to 1.0.

For a more specific size, a cube of 5 cm square to 10 cm square is preferable.

The pieces are held under pressurized gas to impart foaming properties.9 Factors that impart foaming properties include the type of pressurized gas (hereinafter referred to as 9 foaming agent), pressurizing pressure, pressurizing time, and pressurization. There are various conditions such as temperature.

The blowing agent is preferably selected from air, nitrogen, hydrocarbons, fluorocarbon compounds, or mixtures thereof from the viewpoint of economy and ease of handling.

The pressurizing pressure is 0.1 kg/cm2 or more in gauge pressure10
It is preferable that it is 9/cm2 or less. 0-1kg/c
If it is less than m2, it is difficult to keep it under pressure for a long time, and it is difficult to provide high foaming properties.

On the other hand, if it exceeds 10 kg/cm2, it is not only unnecessary, but also tends to destroy the cell structure of the foam and deteriorate the physical properties of the foam molded product.

The time required to impart foamability to the styrofoam molded strips varies depending on other conditions and is not particularly limited, but approximately 30 minutes or more is required. Further, the atmospheric temperature during pressurization may be below the temperature at which the styrofoam molded article pieces soften and coagulate.

The resulting expandable strips are then optionally mixed with unused pre-expanded styrene resin particles and molded.

From the viewpoint of the strength of the recycled molded product obtained, it is preferable to mix it with unused pre-expanded styrene resin particles, but in this case, from the viewpoint of recycling rate, the amount of mixed pieces should be 10 volume cm or more. is preferable, and from the viewpoint of the physical properties of the obtained recycled styrene molded product, it is preferable that the volume coefficient is 70 or less.

Note that even if only 100 strips are used, it can be used as a specific packaging material.

The type and size (particle diameter) of the unused pre-expanded styrene resin particles used are not particularly limited.

Moreover, the molding conditions etc. can be carried out according to conventional methods.

(Example) Next, the present invention will be explained in more detail with reference to Examples.

Example 1 A styrene foam molded product foamed to 46 times (-46 mf!, /9) was cut into 70 square cubes with a nichrome wire to obtain angular foamed styrene resin pieces with an apparent expansion ratio of 47 times. Gauge pressure 1.0
kg/cm2 of compressed air every hour.

When the foamability was investigated, the foamability before pressurization was 1.2 vol.
/vat (Styrofoam molded product strips are placed in boiling water for 2
Volume ratio when using a separation device (Example 1.2 vol/vol
= 2096 volume increase)), whereas 1.5v
It improved to ol/vol. The pieces of the foamable styrene molded product were filled into a mold having rectangular inner dimensions of 10100 x 100 x 45, and heated for 15 seconds at a steam pressure of 1.2 kg/cm2 to obtain a foamed molded product. The expansion ratio and bending strength of the molded product are shown in Table IK (according to JIS A9511).

Examples 2 to 4 Table 1 shows the foamed polystyrene molded strips obtained in the same manner as in Example 1 and the average particle diameter of the pre-expanded 52 times that of about 2.0.
Old, unused expanded styrene resin particles (manufactured by Hitachi Chemical Co., Ltd.) and Ibis A3-T) were mixed, molded in the same manner as in Example 1, and evaluated. The results are shown in Table 1.

Reference Example 1 Example 10 No expanded styrene foam pieces were used, and all unused expanded styrene resin particles were similarly molded and evaluated. The results are shown in Table 1.

Comparative Examples 1 to 4 The formulations shown in Table 1 were prepared using non-pressurized styrene foam resin pieces or non-pressurized pulverized products using a pulverizer, and molded and evaluated in the same manner as in Example 1. The results are shown in Table 1.

The above examples and other examples are summarized and shown in Fig. 1 shows the amount of fine pieces mixed in a Styrofoam molded product and the bending strength of the molded product (effects of the invention). It can be economically reused without significantly reducing the quality of the product. Furthermore, when used in combination with unused pre-expanded styrene resin particles, the bending strength can be improved compared to unused particles alone.

[Brief explanation of the drawing]

FIG. 1 is a graph showing the relationship between the amount of mixed styrene foam molded products used once and the bending strength of the foamed molded products obtained in Examples of the present invention and comparative feeding.

Claims (1)

[Claims] 1. A method for recycling a once-used styrofoam molded product, in which the styrofoam molded product is first cut into thin pieces, and the thin pieces are held under pressurized gas to impart foamability. A method for manufacturing a recycled styrofoam molded product, the method comprising: 2. The method for manufacturing a recycled styrene molded product according to claim 1, wherein after imparting foamability to the strips, the strips are mixed with unused pre-expanded styrene resin particles and molded. 3. The method for producing a recycled polystyrene molded product according to claim 1 or 2, wherein the pressurized gas is air, nitrogen, hydrocarbon, a fluorocarbon compound, or a mixture thereof. 4. The method for producing a recycled styrene foam product according to claim 2 or 3, wherein the amount of the pieces is 10% by volume or more based on the total amount of the unused pre-expanded styrene resin particles.