JPH06166115A - Manufacture of foamed thermoplastic resin molded body - Google Patents

Abstract

PURPOSE:To retain the satisfactory outer appearance of superior physical strength hardly generating resin powder at the time of being rubbed with an electrical appliance or the like by mixing foaming resin impregnated with a foaming agent with regenerated resin particles and new thermoplastic resin respectively and then prefoaming a mixture to the given expansion ratio and forming prefoamed particles. CONSTITUTION:A waste foamed styrene resin molded body as a starting raw material is crushed into pieces of 100mm size or smaller and then heat melted, defoamed and extruded in an extruder, and then cut into the almost columnar shape of approximately 1mm. New styrene resin is heat melted in the extruder and extruded and cut into the almost columnar shape of approximately 1mm. Then particles are pressurized and impregnated with a foaming agent or particles dispersed in an aqueous medium is impregnated with the foaming agent for the purpose of impregnating regenerated resin particles and resin particles with the foaming agent. Then the particles are prefoamed by water vapor up to approximately expansion ratio of 50 times as much. The mixing ratio of both particles is set as the optimum ratio in compliance with the purpose of use of a foamed styrene molded body to be formed and the required quality, physical strength and the like.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for producing a foamed thermoplastic resin molded article, and more specifically, it recycles a used foamed thermoplastic resin molded article or cutting scraps, defective products and the like produced as a by-product during molding. For example, the present invention relates to a method for producing a foamed thermoplastic resin molded product that can be reused as a building wall heat insulating material, a packaging cushioning material, a container, or the like.

[0002]

2. Description of the Related Art Generally, a foamed thermoplastic resin molded product made of a foamed styrene resin or the like is widely used as a packaging material for home electric appliances, a cushioning material, or a container for transporting seafood, etc. The disposal of used foamed thermoplastic resin moldings has become a major social issue. Therefore,
In recent years, various studies have been conducted to recycle used foamed thermoplastic resin moldings and reuse them as the foamed moldings described above.

Conventionally, a used foamed thermoplastic resin molded body is crushed, heated and melted in an extruder, extruded from a die, cooled, and then cut to prepare pelletized regenerated resin particles, which are regenerated. The resin particles are impregnated with a foaming agent, and the regenerated expandable resin particles obtained in this way are heated and expanded with steam to form regenerated pre-expanded resin particles, which are filled in a foam molding die and steam heat molded. It has been proposed to obtain a foamed thermoplastic resin molded article again by carrying out.

Pre-expansion obtained by crushing a used expanded thermoplastic resin molding to a size of about 1 mm to 10 mm square and then heating a new expandable thermoplastic resin to pre-expand to a predetermined ratio. A method of mixing with resin particles and obtaining a foamed thermoplastic resin molded article in the same manner as the above method has also been proposed.

[0005]

However, in the foamed thermoplastic resin molded article produced by using the regenerated expandable resin particles produced from the foamed thermoplastic resin molded article which has been used by the conventional method, the foamed thermoplastic resin molded article is As a result of inferior heat resistance at the time, the foamed molded article undergoes severe shrinkage, and the adhesion between the foamed particles is poor, so that a molded article having a satisfactory molding appearance cannot be obtained. Further, there is a problem that the physical strength of the foamed molded product is smaller than that of general products.

Further, in a foamed thermoplastic resin molded article prepared by mixing crushed and used foamed thermoplastic resin molded articles, the physical strength of the foamed molded article is smaller than that of general products, and for example, the foamed molded article is used. Has a problem that resin powder is easily generated when it rubs against a home electric appliance or the like, and the resin powder is adsorbed to the home electric appliance or the like by static electricity.

Further, since the used foamed thermoplastic resin molding is mixed with the pre-foamed particles of the new foamable thermoplastic resin at the crushing stage to carry out molding, the resin powder generated at the time of crushing is also used for foam molding. Will be supplied to the mold. This resin powder causes problems such as poor sliding of the piston of the raw material charging device and clogging of steam hole (core vents) slits. In addition, there is also a problem that the resin powder generated when the used foamed thermoplastic resin molded product is crushed is adsorbed to manufacturing equipment such as a crusher or an extruder due to static electricity.

[0008]

Means for Solving the Problems The inventors of the present application have conducted extensive studies in order to solve the above-mentioned problems, and as a result, extruded a used foamed thermoplastic resin molding by heating and melting it in an extruder. , Once the regenerated resin particles of stable quality are produced by cutting, then impregnated with a foaming agent to form regenerated expandable resin particles, and the regenerated expandable resin particles are mixed with new expandable resin particles to be molded. By this, it was found that a resin powder is less likely to be generated when it rubs against a home electric appliance, etc., and a foamed thermoplastic resin molded product having excellent physical properties and a satisfactory molding appearance is obtained, and the present invention is completed. Came to.

That is, the method for producing a foamed thermoplastic resin molded article according to the first aspect of the present invention is a recycled resin produced by heating, melting, extruding, and cutting a waste foamed thermoplastic resin molded article in an extruder. Particles, regenerated expandable resin particles obtained by impregnating a foaming agent, and expandable resin particles obtained by impregnating a new thermoplastic resin with a foaming agent are mixed at an arbitrary ratio, and then these resin particles are mixed. The pre-expanded particles are formed by pre-expanding to a predetermined expansion ratio to form pre-expanded particles.

The method for producing a foamed thermoplastic resin molded article according to the second aspect of the present invention is a recycled resin produced by heating, melting, extruding and cutting a waste foamed thermoplastic resin molded article in an extruder. The particles are impregnated with a foaming agent to form regenerated expandable resin particles, and the regenerated preexpanded particles obtained by pre-expanding the regenerated expandable resin particles to a predetermined expansion ratio and a new thermoplastic resin impregnated with the foaming agent. The expandable resin particles are characterized in that the expandable resin particles are pre-expanded to a predetermined expansion ratio and the pre-expanded particles are mixed at an arbitrary ratio, and then the expanded particles are molded.

[0011]

According to the method for producing a foamed thermoplastic resin molded article of claim 1, the recycled resin particles produced from the waste foamed thermoplastic resin molded article are impregnated with a foaming agent to obtain recycled foamable resin particles, and the recycled resin particles are recycled. The expandable resin particles and the expandable resin particles are mixed, pre-expanded, and molded. Therefore, regenerated expandable resin particles having stable quality can be produced, and the amount of pre-expanded particles to be filled in the mold for foam molding during foam molding becomes constant. As a result, it becomes possible to regenerate a foamed thermoplastic resin molded product that has a good molding appearance without shrinkage and the like, and is unlikely to generate resin powder and has excellent physical strength. That is, it becomes possible to recycle a used foamed thermoplastic resin molded product, or cutting scraps, defective products and the like that are by-produced during molding as a good foamed molded product.

Further, in the method for producing a foamed thermoplastic resin molded article according to a second aspect, the recycled resin particles produced from the waste foamed thermoplastic resin molded article are impregnated with a foaming agent to give recycled foamable resin particles, The regenerated expandable resin particles are pre-expanded to form regenerated pre-expanded particles, and the regenerated pre-expanded particles and pre-expanded particles are mixed and molded. Therefore, regenerated pre-expanded particles having stable quality can be produced, so that the amount of the expanded particles to be filled in the mold for foam molding during foam molding becomes constant. As a result, it becomes possible to regenerate a foamed thermoplastic resin molded product that has a good molding appearance without shrinkage and the like, and is unlikely to generate resin powder and has excellent physical strength. That is, it becomes possible to recycle a used foamed thermoplastic resin molded product, or cutting scraps, defective products and the like that are by-produced during molding as a good foamed molded product.

[0013]

EXAMPLE An example of the present invention will be described below. In the present invention, the waste foamed thermoplastic resin molding used as the starting material is made of a thermoplastic resin such as expanded polystyrene, expanded polyethylene, expanded polypropylene. In the following description, a method of regenerating a foam molded article made of expanded polystyrene will be described as an example.

The waste expanded styrene resin molded product used as a starting material is a molded product obtained by extruding styrene or a copolymer resin containing styrene as a main component with a foaming agent, or particles of the above resin. Includes molded articles obtained by impregnating a foaming agent to form expandable particles, pre-foaming this, and then foam-molding in a fixed mold, various containers,
It includes packaging materials, cushioning materials, and other molded products to be discarded after being used for a certain purpose, cutting scraps produced as a by-product when these molded products are manufactured, or defective molded products. These waste foamed styrenic resin moldings are crushed to a size of 100 mm square or less, preferably 20 mm to 30 mm square, then heat-melted and defoamed in an extruder, extruded and cut, and length 1mm, diameter 3mm or less, preferably 1mm
The regenerated resin particles have a substantially columnar shape.

Further, the new styrenic resin in the present invention includes styrene or a copolymer resin containing styrene as a main component. Examples of the copolymer resin containing styrene as a main component include, for example, an ester of a styrene monomer and α-methylstyrene, acrylonitrile, acrylic acid or methacrylic acid and an alcohol having 1 to 8 carbon atoms, and maleic acid. , Esters of fumaric acid and alcohols having 1 to 8 carbon atoms, maleic anhydride and the like. Further, the above-mentioned styrene or a copolymer resin containing styrene as a main component is divinylbenzene,
A small amount of butadiene, polyethylene glycol dimethacrylate or the like may be contained as a crosslinking agent. These styrene-based resins are heated and melted in an extruder, extruded and cut into substantially cylindrical resin particles having a length of about 1 mm and a diameter of 3 mm or less, preferably about 1 mm.

Various additives such as a filler, a plasticizer, a flame retardant, a lubricant, a colorant, an ultraviolet absorber and an antioxidant are contained in the regenerated resin particles and the base resin of the resin particles. It may have been done.

As a method of impregnating the regenerated resin particles and the resin particles with the foaming agent, for example, a method of pressurizing the above particles to impregnate the foaming agent, or a method of impregnating the particles dispersed in an aqueous medium with the foaming agent is used. And the like. A dispersant may be used in the method of dispersing the particles in an aqueous medium and impregnating the foaming agent. Examples of the dispersant include partially saponified polyvinyl alcohol, polyacrylic acid salts, polyvinylpyrrolidone, carboxymethylcellulose, methylcellulose, calcium stearate, methylenebisstearic acid amide, and other organic compounds such as ethylenebisstearic acid amide, Examples of the inorganic compounds include fine powders which are hardly soluble in water, such as calcium phosphate, calcium pyrophosphate, calcium carbonate, magnesium phosphate, magnesium pyrophosphate, magnesium carbonate and magnesium oxide. In the above method, when an inorganic compound is used as a dispersant, it is preferable to use a surfactant such as sodium dodecylbenzenesulfonate together.

The method of impregnating the new thermoplastic resin with the foaming agent is not limited to the above method. Instead of the method of impregnating the foaming agent in the above aqueous medium, for example,
A method of impregnating a foaming agent in the polymerization process in which a monomer is suspension polymerized in an aqueous medium to produce resin particles, or when a thermoplastic resin is heated and melted in an extruder, the foaming agent is pressed into the extruder. A method of extruding and cutting into so-called quench pellets can also be adopted.

Suitable blowing agents are organic compounds which have a boiling point not higher than the softening point of the styrenic resin and which are gaseous or liquid at normal pressure. Pentadiene,
Hydrocarbons such as hexane and petroleum ether, halogenated hydrocarbons such as dichlorofluoromethane and trifluorochloromethane, low boiling point ether compounds such as dimethyl ether, diethyl ether, dipropyl ether and methyl ethyl ether are used. These foaming agents may be used alone or in combination of two or more. Further, different foaming agents may be used for the regenerated resin particles and the resin particles. Furthermore, the foaming agent may be impregnated in a state where the regenerated resin particles and the resin particles are mixed, or the foaming agent may be separately impregnated in the state where the regenerated resin particles and the resin particles are separated.

The regenerated expandable resin particles and expandable resin particles impregnated with these foaming agents are pre-expanded with steam to an expansion ratio of 5 to 100 times, preferably about 50 times. Incidentally, when producing regenerated expandable resin particles and expandable resin particles, promoting the penetration of the foaming agent into these particles,
Moreover, there is no problem even if a solvent that acts as a foaming aid is used. As such a solvent, aromatic hydrocarbons such as toluene, xylene and ethylbenzene are suitable.

Further, the mixing ratio of the regenerated expandable resin particles and the expandable resin particles or the mixture ratio of the regenerated pre-expanded particles and the pre-expanded particles is required for the application of the expanded styrene resin molded article to be produced. The optimum ratio may be set according to the quality, the physical strength and the like. A specific example is shown below.

80% by volume of the expandable resin particles and 20% by volume of the regenerated expandable resin particles were mixed using a mixer such as a tumbler and pre-expanded to obtain pre-expanded particles. After aging the pre-expanded particles for 12 hours, the foamed styrene resin molded body produced by foam molding has a good molding appearance without shrinkage, etc., resin powder is difficult to generate, and it is sufficiently fused to the inside. In addition, it had the same physical strength as that of the foamed styrene resin molded body produced by foam molding only the expandable resin particles. In addition, the molding conditions when the regenerated expandable resin particles were mixed and foam-molded could be made the same as the molding conditions when only the expandable resin particles were foam-molded.

Styrene foam produced by pre-foaming and then agitating the pre-expanded particles aged for 12 hours and 80 vol% of the pre-expanded particles and 20 vol% of the regenerated pre-expanded particles by using a mixer such as a tumbler and foam molding. The resin molded product has a good molding appearance without shrinkage and the like, resin powder is hard to generate, and it is well fused to the inside, and a foamed styrene resin produced by foam molding only pre-expanded particles. It had the same physical strength as the molded product. In addition, the molding conditions when the recycled pre-expanded particles were mixed and foam-molded could be made the same as the molding conditions when only the pre-expanded particles were foam-molded.

As a result, the waste foamed styrene resin molded product can be recycled as a foamed styrene resin molded product which has a good molding appearance without shrinkage and the like, and which does not easily generate resin powder and has excellent physical properties. There was found.

As described above, it is possible to obtain a foamed styrene resin molding having a beautiful molding appearance and excellent physical properties such as bending strength and compression strength. Also,
The molding conditions when the waste foamed styrene resin molded product is mixed and foam-molded can be the same as the molding conditions when only the new styrene resin is foam-molded. As a result, it is possible to recycle used foamed styrenic resin molded products, or cutting scraps, defective products, and the like that are by-produced during molding as good foamed molded products and reuse them.

The above embodiment is not intended to limit the present invention, and various modifications can be made within the scope of the present invention. Further, when the waste foamed styrene-based resin molded product is heated and melted, it is desirable to perform vacuum suction from, for example, a vent port of an extruder, whereby the volatile content in the recycled resin particles can be reduced. Furthermore, it is possible to minimize the variation in volatile components due to the type of waste expanded styrene resin molded product used as a starting material, which is advantageous for stabilizing the quality of the obtained expanded styrene resin molded product.

Further, although the above-mentioned embodiment has been described by taking the method of regenerating the foamed molded article made of expanded polystyrene as an example, it goes without saying that the waste made of a thermoplastic resin such as expanded polyethylene or expanded polypropylene is used. A foamed thermoplastic resin molded article can be recycled as a good foamed molded article by the same method.

[0028]

As described above, in the method for producing a foamed thermoplastic resin molded article according to the present invention, the waste foamed thermoplastic resin molded article is heated and melted in the extruder, extruded and cut. The regenerated expandable resin particles obtained by impregnating the regenerated resin particles produced by the method with a foaming agent and the expandable resin particles obtained by impregnating a new thermoplastic resin with the foaming agent were mixed at an arbitrary ratio. Then, these resin particles are pre-expanded to a predetermined expansion ratio to obtain pre-expanded particles, and the pre-expanded particles are molded.

Therefore, since it is possible to produce regenerated expandable resin particles of stable quality, it is possible to reduce the shrinkage of used expanded thermoplastic resin moldings, cutting scraps produced by molding, defective products and the like. It has an effect that it can be regenerated as a foamed thermoplastic resin molded body which has a good molding appearance and is hard to generate resin powder and has excellent physical strength.

The method for producing a foamed thermoplastic resin molding according to claim 2 of the present invention is produced by heating, melting, extruding and cutting a waste foamed thermoplastic resin molding in an extruder as described above. The regenerated expandable resin particles obtained by pre-expanding the regenerated expandable resin particles to a predetermined expansion ratio by impregnating the regenerated expanded resin particles with a foaming agent, and a new thermoplastic resin as a foaming agent. Are expanded to form expandable resin particles, and the expandable resin particles are pre-expanded to a predetermined expansion ratio, and the pre-expanded particles are mixed at an arbitrary ratio, and then the expanded particles are molded.

Therefore, since it is possible to produce regenerated expandable resin particles having stable quality, it is possible to reduce the shrinkage of used expanded thermoplastic resin molded products or cutting wastes, defective products and the like that are by-produced during molding. It has an effect that it can be regenerated as a foamed thermoplastic resin molded body which has a good molding appearance and is hard to generate resin powder and has excellent physical strength.

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Claims (2)

[Claims] 1. Regenerated expandable resin particles obtained by impregnating regenerated resin particles produced by heating and melting a waste foamed thermoplastic resin molded product in an extruder, extruding, and cutting, and a foaming agent. After mixing the expandable resin particles obtained by impregnating a new thermoplastic resin with a foaming agent at an arbitrary ratio, these resin particles are pre-expanded to a predetermined expansion ratio to give pre-expanded particles. A method for producing a foamed thermoplastic resin molding, which comprises molding. 2. Regenerated resin particles produced by heat-melting a waste foamed thermoplastic resin molded product in an extruder, extruding, and cutting, are impregnated with a foaming agent to form regenerated expandable resin particles, and the regenerated resin particles are regenerated. Regenerated pre-expanded particles obtained by pre-expanding expandable resin particles to a specified expansion ratio, and new thermoplastic resin impregnated with a foaming agent to form expandable resin particles, and these expandable resin particles are pre-expanded to a specified expansion ratio. A method for producing a foamed thermoplastic resin molded product, which comprises mixing the thus-obtained pre-expanded particles at an arbitrary ratio and then molding these expanded particles.