JPH06182891A - Manufacture of reclaimed foamed polystyrene series resin molded form - Google Patents

Abstract

PURPOSE:To easily obtain a reclaimed foamed molded form of high quality with reduced consumption of heat energy without complicated step by pulverizing waste foamed polystyrene molded form, heat shrinking it to reduce in volume it, supplying it into a mold and introducing steam having a higher temperature than a softening point of a base material resin to heat it. CONSTITUTION:Waste foamed polystyrene series resin molded form is cleaned, and then pulverized to foamed resin particles of substantially spherical, stereoscopic state, etc., by a pulverizer, a cutter, etc. Its mean particle size is generally 5-50m and desirably about 10-30mm. Then, the particles are so heat shrinked to be reduced in volume in a range of 1-10min by using heated air as to become 75% or less of original bulky volume. The particles reduced in the volume are supplied into a mold, and steam of a temperature range higher by 10-40 deg.C than a Vicat softening temperature of the base material resin is introduced to heat it, thereby obtaining a foamed molded form.

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 regenerated expanded polystyrene resin molded product for recycling a used expanded polystyrene resin molded product or a waste expanded molded product such as a defective product produced as a by-product during molding. It is a thing.

[0002]

2. Description of the Related Art Expanded polystyrene resin moldings are used in large quantities as cushioning packaging materials for home electric appliances, containers for transporting seafood and fresh foods, and on the other hand, used foam moldings. Waste disposal measures have become a major social issue. Therefore, in recent years, various studies have been carried out in order to regenerate used expanded polystyrene resin molded articles to obtain expanded polystyrene regenerated resin particles capable of producing good expanded molded articles. .

As a conventional method for producing regenerated expandable resin particles, a used expanded polystyrene resin molding is crushed, heated and melted by an extruder, then extruded with a die to be cooled, and then cut. There is known a method in which regenerated expandable resin particles are obtained by impregnating a pellet with a foaming agent such as butane or pentane in a water-dispersed state. Also known is a method of producing regenerated expandable resin particles by press-fitting a kneading agent into a molten resin in an extruder, kneading, extruding with a die, cooling and cutting.

[0004]

However, the expandable polystyrene resin particles produced by the above conventional method are
In a regenerated foamed molded product that is heat foamed with steam, not only the cells become extremely fine and the heat resistance deteriorates, but also the adhesion between the pre-foamed particles is poor, so that one having a satisfactory molded appearance is obtained. I can't. In addition, this foamed molded product has drawbacks such as low mechanical strength.

In Japanese Patent Publication No. 58-24449, therefore, polystyrene resin particles which have already been foamed are used as a raw material, an organic solvent is added thereto in a water-dispersed state, and the mixture is stirred above the softening point of the resin, butane, pentane, etc. The method of impregnating the foaming agent has been proposed. In addition, Japanese Examined Japanese Patent Sho 58-244
In JP-A-50, the same resin particles are used as a raw material, and a styrene monomer is gradually added to the resin particles in a water dispersion system so that the resin particles are absorbed and heated to carry out polymerization. A method of impregnating a foaming agent such as butane or pentane has been proposed. However, the expandable polystyrene resin particles obtained by these methods have a large number of bubbles constituting the original foam-molded body disappeared to become resin particles having no bubbles, which are obtained by foam-molding them. The foam state, mechanical strength, etc. of the foamed molded product obtained are improved to some extent, but are not always sufficient. And with these methods,
Since the expanded polystyrene resin molded product is restored to its original state of non-expanded resin particles and then regenerated as expandable resin particles, it takes man-hours and requires a lot of heat energy. Therefore, it is disadvantageous in terms of manufacturing cost.

As described above, according to the conventional method, since the bubbles forming the foamed molded product are once eliminated to produce resin particles containing no bubbles, not only the process is complicated but also the heating is performed. Therefore, there is a problem that a lot of energy is consumed and the quality of the regenerated foamed molded product obtained is deteriorated due to deterioration of the resin due to heating.

The present invention has been made in view of the above-mentioned conventional problems, and an object of the present invention is to provide a foamed resin particle obtained by crushing a used foamed molded product, without the conventional complicated steps. Moreover, the present invention provides a method for producing a regenerated expanded polystyrene resin molded product, which can easily obtain a high quality regenerated expanded molded product without consuming a large amount of heat energy.

[0008]

Means for Solving the Problems The inventors of the present invention have conducted extensive studies in order to solve the above problems, and as a result, reduced the volume of foamed resin particles obtained by crushing a used foamed molded product with heated air. After the chemical treatment, it is filled in a molding die and heat-molded, so that a high-quality regenerated foamed molded product can be easily obtained without going through the conventional complicated process and consuming a large amount of heat energy. The present invention has been completed and the present invention has been completed.

That is, according to the method for producing a recycled expanded polystyrene resin molded product of the present invention, the expanded resin particles obtained by crushing the waste expanded polystyrene resin molded product are 75% of the original bulk volume.
After the volume is reduced by heat-shrinking using a heating gas as shown below, the volume-reduced resin particles are supplied into the molding die, and the temperature range is 10 to 40 ° C. higher than the Vicat softening point of the base resin. It is characterized in that a foamed molded article is obtained by introducing and heating the above steam.

Further, according to the present invention, the foamed resin particles obtained by crushing and reducing the volume of the waste expanded polystyrene resin molded article are molded into foamed resin particles under a moderate temperature at which the particles do not coalesce and under pressure. The foamed resin particles after being filled in the mold were supplied into the molding mold while being compressed using a pressurized gas so that the bulk volume of the foamed resin particles was 80% or less of the original bulk volume, and the pressure was 10 higher than the Vicat softening point of the base resin. It is characterized in that a foamed molded product is obtained by introducing steam in a temperature range higher by -40 ° C and heating and fusing.

In the present invention, the resin constituting the waste expanded polystyrene resin molding used as the starting material is a styrene polymer, at least 50% by weight or more of a styrene component and another polymerizable unsaturated compound. Examples thereof include copolymers, mixed resins thereof, cross-linked polymers of styrene and polyethylene or polypropylene, and reinforced resins obtained by adding an appropriate amount of a rubber-like substance to these resins. Examples of the above-mentioned copolymerizable unsaturated compound include α-methylstyrene, acrylonitrile, an ester of acrylic acid or methacrylic acid and an alcohol having 1 to 8 carbon atoms, maleic acid, fumaric acid and 1 to 8 Esters with alcohols having carbon atoms, maleic anhydride, etc., and as a small amount of a crosslinking agent, divinylbenzene,
Butadiene, polyethylene glycol dimethacrylate, etc. may also be mentioned.

The above-mentioned waste expanded polystyrene resin molded article is pre-expanded with expandable resin particles obtained by impregnating the above polystyrene resin particles with a foaming agent, and then foam-molded in a predetermined molding die. The obtained foamed molded article, which has been used for various containers, cushioning packaging materials, and certain other purposes, and has been used for disposal, and a secondary molded article when these molded articles are manufactured. Includes raw defective products.
The waste expanded polystyrene resin molded product is not limited to the foamed molded product obtained by foaming and molding in a predetermined molding die, but the foamed molded product obtained by extruding and foaming the above resin has been used. It is also possible to use a molded product, a defective molded product, a cutting waste during trimming, or the like as a raw material. In addition, various additives such as a filler, a plasticizer, a flame retardant, a lubricant, a colorant, an ultraviolet absorber and an antioxidant may be contained in the resin forming the foamed molded article.

Further, in the present invention, the base resin of the waste expanded polystyrene resin molding used as a starting material is
It is desirable to use a single resin type, but the thermal properties of the foam molded product (foam moldability), cell size (molded product appearance)
Can be used by mixing two or more kinds of base resins.

Further, the waste expanded polystyrene resin molded product has a different foaming multiple depending on its use, but in order to obtain a homogeneous regenerated foamed molded product by the method of the present invention, moldings having substantially the same foaming multiple are separated. It is desirable to use it separately as a raw material. The cushioning packaging material for home electric appliances, the container for seafood, the apple box, etc., which occupy most of the waste foamed molded product, is a foamed molded product having a foaming multiple of 50 to 60 times. However, if it is within such a variation range, it can be used as the raw material of the present application without any trouble.

Next, a method for producing a regenerated expanded polystyrene resin molding will be described below.

First, the waste expanded polystyrene resin molded product is washed and the like, and then crushed by a crushing machine or a cutting machine or any other method into foamed resin particles having a substantially spherical shape or a cubic shape. To be done. The average particle diameter of the foamed resin particles is appropriately determined according to the size of the molded body to be refoamed and molded, but is generally 5 to 50 mm, preferably about 10 to 30 mm. If the average particle size is larger than 50 mm, the pipes may be clogged during pneumatic transportation and the moldability may be poor. On the other hand, when the average particle size is smaller than 5 mm, the bubbles inside the foamed molded product are destroyed when the foamed molded product is crushed, the closed cell ratio is lowered, and sufficient foamability cannot be obtained during foamed molding. A normal foam molding cannot be obtained.

The closed cell ratio of the expanded resin particles used in the present invention must be 65% or more, preferably 80% or more. When a large amount of inappropriate fine particles generated when the foamed molded product is crushed, it is desirable to remove the fine particles by sieving. Further, as a crusher or a cutter, a crusher or a crusher which does not break the bubbles of the foamed molded article as much as possible, suppresses the generation of fine particles, has a uniform particle size, and can obtain desired foamed particles having a spherical shape or a shape close to a cube is preferable. Used for.

Next, the expanded resin particles are reduced in volume by using heated air. The volume reduction treatment of the expanded beads is performed at a temperature higher by 10 ° C. to 60 ° C., preferably 25 ° C. to 50 ° C. higher than the Vicat softening point (T _S ) of the base resin. The preferred temperature range varies depending on the base resin of the expanded resin particles to be used, but if the temperature is lower than the Vicat softening point + 10 ° C, it takes a long time to reduce the volume and it is difficult to put it into practical use.
On the other hand, at a temperature higher than the Vicat softening point + 60 ° C., the expanded particles are coalesced with each other, and the volume reduction is so rapid that it is difficult to achieve a uniform volume reduction that is normal for mass production.

Under the above temperature conditions, there is no risk of the expanded resin particles sticking to each other. Therefore, the heated air is introduced while the expanded particles are left in the container, or
The volume reduction treatment can be performed by introducing the expanded particles into the heated air tank. Also put the foamed particles in the container,
The volume reduction treatment may be performed by rotating the container or introducing heated air while stirring with a stirring means installed in the container.

The time required for the volume reduction treatment is appropriately changed depending on the type of the base resin, the temperature of the heated air, the supply amount of the heated air, etc., but it is generally in the range of about 1 to 10 minutes. And more preferably 2 to 5 minutes. When the treatment time is less than 1 minute, the volume is rapidly reduced and it becomes difficult to obtain uniformity in mass production. On the contrary, when it exceeds 10 minutes, the productivity is deteriorated, which is not preferable.

Here, the porosity of ordinary pre-expanded particles is
It is about 35-40%. On the other hand, the expanded resin particles obtained by crushing the waste expanded polystyrene resin particles used in the present invention have a large bulk volume and a porosity of about 50 to 60%.
Becomes

Therefore, when a molded product having a relatively low expansion ratio (about 40 times or less) is remanufactured, the volume reduction of the crushed expandable resin particles by the heated air is reduced by 50% or less, 3 or less.
It can be molded by increasing the content in the range of 0% or more and filling the mold as it is with a usual method.

On the other hand, when a molded product having a relatively high expansion ratio (about 50 times or more) is remanufactured, the volume reduction of the crushed expandable resin particles by the heated air is reduced to a volume reduction ratio of 60% or more and 75% or less. Then, the volume-reduced crushable expandable resin particles are compressed to 80% or less and 60% or more of the bulk capacity with heated air and filled in the mold, then the heated air in the mold is depressurized and compressed into the mold. It is possible to recover the volume of the foamed particles so that the porosity between the particles is 40% or less, and heat-mold with steam to fuse them to each other to obtain a molded product as a molding die.

In the present invention, when a molded product having a relatively high expansion ratio is regenerated, the degree of compression is 80% or less, preferably 70% or less, 60% of the volume of the bulk after volume reduction.
% Or more. If the compression is less than 80% of the bulk volume, the foaming force cannot be obtained during heat molding, and it is difficult to obtain a normal molded product.

Next, heat molding is carried out by introducing pressurized steam into the mold. That is, by the partial pressure between the air and the heated steam in the volume-reduced expanded resin particles,
The reduced-volume expanded resin particles expand to a predetermined expansion ratio.

The above-mentioned water vapor is controlled so as to be in a temperature range 10 to 40 ° C. higher than the Vicat softening point of the base resin,
More preferably, the temperature is adjusted to a temperature range 15 to 30 ° C. higher than the Vicat softening point. In the temperature range where the water vapor temperature at the time of heat molding is lower than the Vicat softening point + 10 ° C., the foaming speed becomes slow and the air inside the foamed particles escapes to the outside so that a sufficient foaming effect cannot be obtained. As a result, a high quality foamed molded product cannot be obtained.

Further, in the temperature range exceeding the Vicat softening point + 40 ° C., the foaming suitability range becomes extremely narrow, and it is extremely difficult to obtain an industrially normal foamed molded product. The time required for heat-molding varies depending on the size of the foam-molded product to be obtained, the expansion ratio, etc., but is generally 10 to 1
It is 80 seconds, preferably about 15 to 90 seconds.
Further, as the water vapor, it is also possible to use a water vapor-air mixed medium.

In the present invention, in order to maintain the compressed state of the expanded resin particles, it is desirable to maintain the pressure inside the mold before and during the filling of the expanded resin particles. The expansion ratio of the recycled foamed molded product obtained by heat-molding the expanded resin particles is determined by the expansion ratio of the original waste expanded resin molded product and the compression ratio of the expanded resin particles under pressure, and the expanded particles in the molding die The multiplication factor of is the foaming factor of the recycled foam molded article. Therefore, it is necessary to set the internal pressure in the molding die to a predetermined pressurization state in advance and press-fill the expanded resin particles. As the gas used for the pressure filling of the foamed resin particles and the pressurization in the molding die, an inorganic gas used at the time of vapor phase impregnation can be used, but normally compressed air is preferably used.

After that, the pressure inside the mold is released and the pressure is released to return the internal pressure of the mold to the atmospheric pressure, the gas between the expanded particles is discharged, and the compressed expanded particles are expanded and restored. Then, steam is introduced into the mold to heat and fuse the expanded particles to form an expanded molded body. The foamed molded product obtained by heat molding can be taken out from the mold after being cooled with cooling water.

The regenerated foamed molded product obtained as described above is suitable as a heat insulating wall material for construction purposes, a lightweight material, a floor base material, an ESP for improving soft ground for civil engineering applications, an embedding material for civil engineering methods, etc. used. In these applications, the regenerated foamed molded product has a relatively thick block shape or plate shape, and since it does not need to be molded into a particularly complicated shape, it can be used without any trouble. In addition, the foaming multiple of the foamed molded product desired in these applications is 4
It is about 0 to 50 times, and a buffer packaging material for used home electric appliances, a transportation container for seafood or fresh food, and the like can be preferably used as the raw material of the present invention.

When the recycled foamed molded product obtained by the present invention is used for the above-mentioned construction use or civil engineering use, it is necessary to impart self-extinguishing property and flame retardancy to the foamed molded product. . In order to impart self-extinguishing property and flame retardancy to the regenerated foam molded article, the surface of the foamed resin particles may be subjected to a covering treatment by adding a flame retardant or, if necessary, a flame retardant aid, and then foam molding. . As the flame retardant, brominated alicyclic compounds, brominated aromatic compounds, brominated aromatic polymers, brominated phenyl (meth) acrylic acid esters and the like are preferably used. If the above flame retardant is in powder form, JIS standard sieve 149μ
It is desirable to use fine powder of m-passage in terms of adhesion to the particle surface. Further, in order to ensure adhesion to particles, a powdery flame retardant may be coated and spread after being partially coated with a liquid flame retardant having an appropriate viscosity. Further, a powdery flame retardant having a relatively low melting point may be heated and dissolved to perform coating treatment. Specific examples of such a flame retardant bring about self-extinguishing property by using a relatively small amount, good adhesion to the surface of the expanded resin particles, does not inhibit fusion between the expanded particles during molding, and has weather resistance. Well, it does not deteriorate the resin substrate. Ether and the like are particularly preferably used. These flame retardants are used in the range of 0.5 to 2.0% by weight, more preferably 0.8 to 1.5% by weight, based on the expanded resin particles. In addition, 0.1 to 0.5% by weight of a compound having an O—O, C—C, N═N bond, such as an organic peroxide, as a flame retardant aid.
You may use it together with the flame retardant. Examples of preferred flame retardant aids include dicumyl peroxide, 1,1-diphenylbicyclohexyl, azodiisobutyronitrile and the like.

Further, the foamed resin particles of the present invention include a surface-treating agent such as a lubricant for improving the filling property in a molding die, a fusion promoter during molding, a molding cooling time shortening agent, an antistatic agent, a colorant and the like. You may coat. Specifically, ethylene bis stearamide, higher fatty acid, higher fatty acid amide, edible oil, higher fatty acid triglyceride, higher fatty acid monoglyceride, paraffin wax, polyethylene wax, zinc stearate and the like can be mentioned.

Such surface coating treatment is carried out by using a ribbon blender, a tumbler, a Loedige mixer, a Nauta mixer, a super mixer, a line mixer or the like.

[0034]

EXAMPLES The present invention will be described below with reference to examples.
The present invention is not limited thereby, and various modifications can be made within the scope of the present invention.

A foam molded product of expandable polystyrene resin particles used as a cushioning packaging material for home electric appliances was crushed with a crusher to a particle diameter of about 10 to 20 mm, and this was used as a starting material for a recycled foam molded product. The crushed foamed resin particles were flame-retarded with 1.2% by weight of bisallyl ether of tetrabromobisphenol and surface-coated with a super mixer. The expanded particles coated with this flame retardant (5000 ml in bulk volume) were placed in a container with a stirrer of 6000 ml, and heated air was blown evenly from the bottom of the container while stirring to reduce the volume of the expanded particles to the desired bulk volume. Turned into

Then, the inner size was maintained at 30 while maintaining the pressure.
The volume-expanded foamed particles were compressed and filled in a molding die having a die cavity of x30 x 2.5 cm using pressurized air.
After the resin particles were filled, the pressurizing state of the molding die was released, and steam at a predetermined temperature was introduced to heat and foam to produce a regenerated foamed molded body.

Table 1 shows the processing conditions for volume reduction, the molding conditions in the molding die, and the regenerated foamed moldings obtained.
Vicat softening point is JIS K-7206 (B method 5k
It was measured according to gf). The waste foamed molding used as a starting material is a buffer packaging material for home appliances that has been used once. Example 1 and Comparative Examples 1 to 6 are 55 times foam molded articles, and Example 2 is 60 times foam molded. The products, Examples 3 and 4, are 40-fold foam molded products. Further, these base resins are polystyrene. Example 5 is 92% styrene
And a maleic anhydride 8% copolymer 40 times foam molded article.

In each of Examples 1 to 5, there was no problem in manufacturing,
The regenerated foamed molded product thus obtained was of high quality which was homogeneous and had good fusion bonding. Regarding the obtained regenerated foam molded article, JI
As a result of evaluating the self-extinguishing property according to the combustion test method by the oxygen index method of SK-7201, the oxygen index is 26 or more,
It had good flame retardancy. On the other hand, in Comparative Example 1, the volume reduction temperature was too high, and the volume reduction of the expanded resin particles became too rapid, resulting in non-uniformity. In Comparative Example 2, the volume reduction temperature was too low, and it took a long time to reduce the volume, which was insufficient in practice. In Comparative Example 3, the volume reduction was insufficient, and the obtained molded product contracted leaving a space. In Comparative Example 4, the molded product obtained due to insufficient compression when filled in the mold shrinks leaving a space. In Comparative Example 5, fusion was poor due to insufficient heat during molding. Comparative Example 6 contracted due to excessive heat during molding.

[0039]

[Table 1]

[0040]

According to the present invention, foamed resin particles obtained by crushing a used expanded polystyrene resin molded product are heat-shrinked with heated air to reduce the volume and then foam-molded with a molding die, or Then, the foamed particles, the volume of which is further reduced, are filled in a molding die in a compressed state and heated to foam-mold.

Thus, the normal bubbles of the expanded particles can be used as they are without the conventional complicated steps of reducing the volume of the waste expanded molded product, re-pelleting, impregnation of the foaming agent, pre-expanding, and heat molding. It is possible to easily produce a high-quality recycled foamed molded product without consuming a lot of heat energy. The regenerated foamed molded product obtained by the present invention can be used in many fields including construction and civil engineering.

Further, the method for producing a regenerated foamed molded article of the present invention can effectively recycle a large amount of used foamed molded article, and has great effects as a disposal treatment measure or an effective use of resources. The effect of being able to be played.

Claims (3)

[Claims] 1. The volume of foamed resin particles obtained by crushing a waste expanded polystyrene resin molded product is reduced by thermally shrinking the expanded resin particles with heated air so that the volume of the expanded resin particles becomes 75% or less of the original volume. Regenerated foaming, characterized in that a foamed molded body is obtained by supplying the resin particles thus converted into a molding die, introducing steam in a temperature range 10 to 40 ° C. higher than the Vicat softening point of the base resin, and heating the foamed molded body. A method for producing a polystyrene resin molded body. 2. The method for producing a regenerated expanded polystyrene resin molded article according to claim 1, wherein the temperature of the heated air is in a temperature range higher by 10 to 60 ° C. than the Vicat softening point of the base resin. 3. The volume-reduced resin particles are compressed with pressurized air so that the bulk volume after filling the mold is 80% or less of the original bulk volume, and the resin particles are supplied into the mold. The method for producing a regenerated expanded polystyrene resin molded article according to claim 1.