JP2001131334A - Recycling process for polystyrene resin waste - Google Patents

Abstract

PROBLEM TO BE SOLVED: To realize a process enabling high quality polystyrene resin to be recycled from flame retardant-containing polystyrene resin wastes. SOLUTION: The flame retardant-containing polystyrene resin wastes are dissolved in an organic solvent, the resultant solution is added with at least one kind selected from the group consisting of a lower alkoxide, a magnesium oxide and/or aluminum oxide-containing adsorbent and activated carbon in order for the above flame retardant to be adsorbed and removed, and polystyrene resin is separated and collected. A residual flame retardant quantity in the separated and collected polystyrene resin is set being <=1 wt.%. The solution from which the flame retardant has been adsorbed and removed is subjected to vacuum heating and devolatilization to remove and collect the residual organic solvent, and the polystyrene resin is separated and collected. The adsorbed and removed flame retardant is decomposed with treated water at >=270 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for efficiently recovering styrene resin from waste styrene resin such as waste foamed styrene and recycling the recycled styrene resin as recycled styrene. The present invention relates to a method for recycling styrene resin waste containing a combusting agent.

[0002]

2. Description of the Related Art Styrofoam containing flame retardants used in building materials or styrene-based waste materials such as TV cabinets contain about 1 to 10% by weight of halogen-based flame retardants. At present, there is no effective method, and most are landfilled, recycled to blast furnace raw materials, or incinerated.

[0003] The reason for this is that a styrene resin containing several wt% of a flame retardant is exposed to air or an extruder.
This is because, when the material is recycled at a temperature of 0 ° C. or higher, the flame retardant is thermally decomposed to generate an acid, and the physical properties of styrene are significantly reduced, or the generated acid rusts the processing apparatus. In general, a halogen-based flame retardant is used as the flame retardant.
Under the following combustion conditions, generation of dioxins is also a concern.

[0004] From the above, it is desired to increase the recycling rate of waste materials such as building materials and TV cabinets. In this case, it is essential to increase the recycling rate of plastic parts.

However, as described above, for example, the recovered TV cabinet material contains a brominated flame retardant such as decabrom diphenyl ether, and how to separate the brominated flame retardant from the styrene component is determined. It is the key to improving the recycling rate.

[0006]

As described above, for example, when a collected TV cabinet is recycled and used again as a TV cabinet, it is necessary to remove the brominated flame retardant.

[0007] As a method for separating low molecular weight components such as flame retardants in resin such as waste styrene resin, the resin is dissolved in an organic solvent to form a solution, and the solution is mixed with a poor solvent such as ethanol or hexane to precipitate. A method for recovering a styrene resin is known. For example, Japanese Patent Application Laid-Open No. 7-214028 discloses a method in which styrofoam containing a flame retardant is dissolved with limonene, and the dissolved product is mixed with a lower alcohol or an aqueous solution thereof to collect a generated precipitate.

However, in this method, it is difficult to recycle as recycled styrene. Since a solvent or a flame retardant which cannot be completely removed remains in the precipitated resin, it is apparent that the resin cannot be used as a recycled material unless the residual solvent and the residual flame retardant in the resin are reduced to a predetermined amount or less.

Usually, vacuum heating and devolatilization are generally used as a method for removing a solvent from a resin precipitate containing a residual solvent. However, depending on the separation conditions such as the temperature and the degree of vacuum, the solvent may remain in the recovered styrene resin, and the heat resistance and the tensile strength may be significantly reduced. Also,
In the method of precipitating a resin using a lower alcohol, usually 20 to 30% of alcohol is added to the styrene foam solution, or a several-fold amount of the lower alcohol is added to the solution to reprecipitate the resin. In addition, there is a problem that the process becomes complicated, for example, a large amount of lower alcohol is required, and it is also necessary to separate and purify the alcohol.

Therefore, when the styrene waste containing the flame retardant is dissolved in a specific organic solvent and the flame retardant is removed and recycled, a simpler method is preferred as a method for removing the flame retardant. Further, controlling the removal rate of the flame retardant and the amount of the residual solvent in the styrene resin after separating the solvent within a range that does not reduce the mechanical properties is important in performing high-quality recycling of the styrene resin waste material containing the flame retardant. Is necessary.

On the other hand, the removed flame retardant can be reused as long as the type is limited. Usually, however, there are many types of flame retardants used in various kinds of discarded home appliances, and a mixture of flame retardants is used. In such cases, the applications of reuse may be limited, or the commercial value may be lost, and the recovered flame retardant must be disposed of as industrial waste or must be detoxified. In recent years, in view of the fact that the disposal cost of industrial waste, particularly waste containing halogen, is high and the disposal site is tight, a technology for detoxification is required in the future.

Accordingly, the present invention has been proposed in view of such a conventional situation, and it is possible to efficiently remove a flame retardant and to recycle high-quality styrene resin waste material containing a flame retardant. An object of the present invention is to provide a method for recycling styrene resin waste material that can be performed.

Another object of the present invention is to provide a series of recycling processes until the removed flame retardant is rendered harmless.

[0014]

In order to achieve the above-mentioned object, a recycling method of the present invention comprises dissolving a styrene resin waste containing a flame retardant in an organic solvent, and adding a lower alkoxide, magnesium oxide and / or magnesium oxide to the solution. Alternatively, a styrene resin is separated and recovered after the flame retardant is adsorbed and removed by adding at least one selected from an adsorbent containing aluminum oxide and activated carbon.

Further, the adsorbed and removed flame retardant is heated at 270 ° C.
It is characterized by being decomposed with the above treated water.

The flame retardant is efficiently removed from the styrene waste material containing the flame retardant by adding a specific adsorbent, and the residual flame retardant,
By controlling the amount of the residual solvent to a specified value or less, a high-quality recycled styrene resin is recycled.

The separated halogen-based flame retardant is rendered harmless (recovers halogens as inorganic salts) with high-temperature water (supercritical water).

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a method for recycling styrene resin waste material to which the present invention is applied will be described in detail.

According to the present invention, a styrene resin waste material such as styrene foam or a styrene cabinet is dissolved and reduced in volume in an organic solvent, the solution is transported to a recycling plant, and the organic solvent is removed and recovered by vacuum heating and devolatilization. In a styrene resin waste material recycling system to be recycled as styrene, a flame retardant is efficiently removed and high-quality recycled styrene is recycled.

The object to be treated is styrene resin waste material in general, and its form and properties are not limited, such as styrene foam waste material containing a flame retardant and high impact styrene cabinet waste material containing a flame retardant.

These styrene resin waste materials are first dissolved in an organic solvent. The organic solvent has a dissolving power of 15% by weight or more at room temperature and a boiling point of 200 ° C.
It is preferred to use an organic solvent that is less than.

By using an organic solvent having a dissolving power of 15% by weight or more at room temperature as an organic solvent for dissolving the styrene resin waste material, the amount of the organic solvent used can be reduced, Work efficiency in the volatile process can be improved.

Further, by using an organic solvent having a boiling point of less than 200 ° C. as an organic solvent for dissolving the styrene resin waste material, the working efficiency in the vacuum heating and devolatilization step can be improved. Can be reliably reduced.

Examples of the organic solvent used include aromatic organic solvents, ketone organic solvents, and monoterpene organic solvents. And from the viewpoint of environmental conservation,
It is preferable to use an organic solvent containing no halogen, and specific examples include toluene, d-limonene, ethylbenzene, tetrahydrofuran, methyl ethyl ketone, and monoterpene solvents. Among them, d
Limonene is an organic solvent suitable for this application. d-
Limonene is a vegetable oil extracted from citrus peels, is also used as a food additive, has high safety and high styrene foam solubility, and is optimal as a solvent used in the present invention.

It is desirable to remove insoluble components from the solution in which the styrene resin waste material containing the flame retardant is dissolved in the organic solvent by using a method such as centrifugation, decantation, or filtration in advance.

Next, the flame retardant is removed.

When recycling the styrene resin waste material containing the flame retardant, if the styrene resin containing several weight% of the flame retardant is heated to 200 ° C. or more, the flame retardant is thermally decomposed to generate an acid. As a result, material properties such as heat resistance and tensile strength of the recycled styrene resin are significantly reduced, and the quality is greatly reduced. Further, the treatment equipment is corroded by the acid generated by the thermal decomposition of the flame retardant. Therefore, when recycling the styrene resin waste material containing the flame retardant, it is important to reduce the flame retardant contained in the styrene resin before the heating step, and the amount of the residual flame retardant in the styrene resin is 1% by weight. It is preferable to set the following. If the amount of the residual flame retardant in the styrene resin is more than 1% by weight, the above-mentioned acid significantly lowers the material properties such as heat resistance and tensile strength of the regenerated styrene resin, and the quality is greatly reduced. . Further, the treatment equipment is corroded by the above-mentioned acid. Therefore, by regulating the amount of the residual flame retardant in the styrene resin to 1% by weight or less, the material characteristics of the recycled styrene resin can be favorably maintained, and the corrosion of the processing equipment can be prevented. is there.

In the present invention, a specific adsorbent is used for removing the flame retardant. Specific examples include lower alkoxides, adsorbents containing magnesium oxide and aluminum oxide, and activated carbon.

As the lower alkoxide, an alkoxide of an alcohol having 5 or less carbon atoms is preferable. For example, sodium methoxide, sodium ethoxide, sodium butoxide, potassium butoxide, magnesium ethoxide, aluminum propoxide and the like can be used.

Examples of the adsorbent containing magnesium oxide or aluminum oxide include a magnesium oxide-based hydrotalcite adsorbent.

The amount of the adsorbent added to the solution is preferably 0.5 to 5% by weight. If the amount is too small, the flame retardant cannot be sufficiently removed. If the amount is too large, not only will it be wasted, but it will hinder subsequent processes.

The adsorbent having adsorbed the flame retardant can be easily separated and removed by using a technique such as centrifugation, decantation, or filtration.

The solution in which the flame retardant has been adsorbed and removed by the adsorbent is subjected to, for example, vacuum heating and devolatilization to remove and recover the residual organic solvent, and to separate and recover the styrene resin.

The residual solvent in the styrene resin significantly reduces the material properties such as heat resistance and tensile strength of the regenerated styrene resin, and causes the quality to largely deteriorate. The recycled styrene resin has a diameter of, for example, 3 mm,
It is made into a regenerated styrene pellet having a length of about 3 mm. Then, the residual solvent in the recycled styrene pellets remains as it is in a product manufactured from the pellets.
Therefore, if a large amount of the residual solvent is present in the recycled styrene pellets, the material properties of a product manufactured using the same are reduced, and the quality is reduced.

Therefore, it is important to define the amount of the residual solvent in the styrene resin, and it is preferable that the amount of the residual solvent in the styrene resin is 0.4% by weight or less. When the amount of the residual solvent in the styrene resin is more than 0.4% by weight, material properties such as heat resistance and tensile strength of the recycled styrene resin are significantly reduced, and the quality is greatly reduced. Therefore, by regulating the amount of the residual solvent in the styrene resin to 0.4% by weight or less, high-quality recycled styrene having good material properties can be recycled.

In the styrene resin recycling process, a hot process is included. Even if the process is performed in a vacuum, if the recycling is repeated, the styrene resin is oxidized under the influence of residual oxygen, and the molecular weight of the regenerated styrene resin decreases. Would. When the molecular weight decreases, the tensile strength, impact strength, and the like decrease, which causes a great decrease in quality. Therefore, in order to prevent oxidation of the recycled styrene resin, it is preferable to add an antioxidant to the solution in which the styrene resin is dissolved before performing the hot step.
Thereby, when heat is applied to the styrene resin in the hot step, it is possible to prevent the styrene resin from being oxidized and the molecular weight from decreasing.

As antioxidants, phosphorus-based, phenol-based, and sulfur-based oxides are widely used. However, when a vacuum heating step is performed, an antioxidant having a low vapor pressure may be used. preferable. Specifically, hindered phenolic antioxidants can be suitably used.
The hindered phenolic antioxidant is preferably added in an amount of 0.01 to 0.5% by weight based on the weight of the styrene resin waste material. Further, the hindered phenolic antioxidant preferably has a vapor pressure at 20 ° C. of 10 ⁻⁷ Pa or less. This prevents oxidation of the styrene resin even when a hot step is performed,
That is, a decrease in the molecular weight of the styrene resin can be prevented. Then, even when the hindered phenolic antioxidant is added in an amount of 0.01 to 0.5% by weight, the heat resistance of the styrene resin maintains good characteristics without lowering, and the high-quality styrene resin is recycled. be able to.

Further, among the hindered phenol-based antioxidants, antioxidants having a low vapor pressure have a particularly high antioxidant effect on the styrene resin, and the use thereof can further increase the number of recycles.

The heating temperature at the time of performing the above-mentioned vacuum heating devolatilization is preferably lower than 260 ° C. Heating temperature 2
When the temperature is 60 ° C. or higher, thermal decomposition of the styrene resin occurs, so that the material properties such as heat resistance and tensile strength of the regenerated styrene resin are significantly reduced, and the molecular weight of the regenerated styrene resin is greatly reduced, and the quality is greatly reduced. Because it will. Therefore, by setting the heating temperature at the time of performing the vacuum heating devolatilization to less than 260 ° C., good material characteristics are maintained, and high-quality styrene resin can be recycled.

On the other hand, the adsorbed and removed flame retardant is decomposed with treated water (so-called supercritical water) at 270 ° C. or higher. The halogen-based flame retardant can be recovered as an inorganic acid by treating with water at a temperature of 270 ° C. or higher.

At this time, the treated water used preferably contains 0.1 to 5% by volume of hydrogen peroxide solution. Thereby, the halogen-based flame retardant can be efficiently decomposed.

In consideration of the corrosion of the processing apparatus, it is preferable to set the hydrogen ion concentration pH at normal temperature to 4 to 10 by adding ammonia to the treated water.

Examples of methods for decomposing and detoxifying organic substances containing halogen include an alkali decomposition method and a supercritical water oxidation method. The former method is to add alkali and decompose by heating (normal pressure)
However, there are problems such as a long reaction time (several hours or more), residue generation, exhaust gas treatment, and the like, and there remains a question as to whether it can be completely decomposed. It is reported that the supercritical water oxidation method can decompose 99.9999% or more in a few minutes in the case of PCB (polychlorobiphenyl), and the residue after the decomposition can be made only from an aqueous solution of an inorganic salt. Therefore, it is effective as a technique for decomposing and detoxifying halogen-based flame retardants (for example, decabromodiphenyl ether) generally contained in TV cabinets, styrofoam for building materials, printed wiring boards and the like.

[0044]

EXAMPLES Hereinafter, specific examples of the present invention will be described based on experimental results.

In each of the embodiments, as high-impact polystyrene (HIPS,
Flame retardant: 10% by weight). As an organic solvent for dissolving styrene, d-limonene having a purity of about 95% (manufactured by Yashara Chemical Co., Ltd.) was used. d-limonene is
It is a vegetable essential oil extracted from citrus peel and is also used as a food additive, has high safety and high styrene solubility, and is optimal as a solvent used in the present invention.

The amounts of the residual solvent and the flame retardant were determined by GPC (gel permeation chromatography), which can simultaneously measure the molecular weight, the residual solvent amount and the flame retardant amount.
It was calculated from the peak area of the remaining flame retardant (detector: refractometer). The flame retardant amount (halogen amount) in the regenerated resin was determined by ion chromatography using halogen generated by burning the resin. Regarding the decomposition of the halogen-based flame retardant by high-temperature water, halogen ions contained in the decomposed aqueous solution were detected by ion chromatography. The detection sensitivity is about 0.01 ppm.

Example 1 First, solubility tests of various organic solvents were performed. Waste TV cabinet containing 10% by weight of bromine-based flame retardant (decabromodiphenyl ether) is toluene (boiling point: 101 ° C.)
Methyl ethyl ketone (boiling point: 80 ° C), tetrahydrofuran (boiling point: 65 ° C), d-limonene (boiling point: 175)
C)) and 30% by weight in dipentene (170-180 ° C) at room temperature. All solvents show good solubility, and toluene, d-limonene and dipentene are 30% by weight at room temperature.
It has the above dissolving ability.

A solution obtained by dissolving 15% by weight of a TV cabinet material containing 10% by weight of a brominated flame retardant (decabromodiphenyl ether) in d-limonene is centrifuged (centrifugal force: 10,000 G) at room temperature to obtain a bromine-based insoluble component. The flame retardant was removed. The amount of residual flame retardant in the resin was 1.5% by weight. Next, a lower alkoxide shown in Table 1 was added to the solution as an adsorbent. After the solution was stirred at 60 ° C. for 1 hour, the solution was centrifuged again (10000 G) to remove the adsorbent. The solvent d-limonene was removed by vacuum drying, and the residual flame retardant was measured by GPC. Table 1 shows the results.

In Table 1, when the residual flame retardant is indicated as 〜0%, the detection limit of GPC is 0.05.
% Or less.

[0050]

[Table 1]

From Table 1, it can be seen that addition of lower alkoxide
It was confirmed that the residual flame retardant amount in the solution could be removed from 10% to almost 100%. In particular, sodium ethoxide,
Potassium-t-butoxide has a high effect of removing residual flame retardants. Sodium ethoxide and potassium-t-butoxide were each added to a 3% solution to reduce residual flame retardant to 0.1% or less. Next, the solution from which the flame retardant had been removed was passed through a bag filter (pore size: about 100 μm), and then subjected to vacuum devolatilization with a vacuum heating separation device. The gas phase temperature in the vacuum chamber is 2
20 ° C (heat medium temperature: 230-240 ° C), degree of vacuum 30
Thor. 50 liters of solution were introduced per hour. The separated solvent is liquefied through a condenser and reused as a regeneration solvent. On the other hand, the molten styrene resin is extruded into a thread form from the lower part of the vacuum heating device by a gear pump, cooled in a cooling bath, and cut by a pelletizer to form regenerated styrene pellets. The decrease in the molecular weight of the recycled material
It was within 5%, and the mechanical properties, such as tensile strength, bending strength, and softening point, were measured.

Example 2 As in Example 1, a solution prepared by dissolving 15% by weight of a TV cabinet material containing 10% by weight of a brominated flame retardant (decabromodiphenyl ether) in d-limonene was centrifuged at room temperature (centrifugal force: 10,000 G). ) To remove the insoluble bromine-based flame retardant. The amount of residual flame retardant in the resin was 1.5% by weight. Next, a synthetic magnesium oxide-based adsorbent shown in Table 2 (trade names: Kyoward 500, 100
0, 2000, magnesium oxide, hydrotalcite DHT-4A, manufactured by Kyowa Chemical Industry Co., Ltd.) and a synthetic aluminum oxide-based adsorbent (trade name: Kyoward 70)
0, manufactured by Kyowa Chemical Industry Co., Ltd.). Further, as a surface-basic natural clay compound, Mizuka Ace # 300 (manufactured by Mizusawa Chemical Industry Co., Ltd.) was examined. 5% by weight adsorbent is added to the centrifuged solution, and the solution is
After stirring at ℃ for 1 hour, centrifugation again (10000G)
And the adsorbent was removed. The solvent d-limonene was removed by vacuum drying, and the residual flame retardant was measured by GPC. The results are summarized in Table 2.

[0053]

[Table 2]

From the results shown in Table 2, it was found that about 50% of the flame retardant can be removed by adding a surface basic oxide adsorbent such as magnesium oxide, aluminum oxide, or clay. It was also confirmed that the removal rate could be further increased by blending with the alkoxide-based adsorbent shown in Table 1. For example, with a 1: 1 blend of sodium ethoxide and Kyoward 1000, the removal rate could be increased to 90%. Also, blending with activated carbon is possible. For example, activated carbon (Evadia 5AP2, A
By adding 5% of G400X (manufactured by Ebara Corporation), about 30 to 50% of the flame retardant could be removed. The adsorbents can be appropriately blended and used in consideration of the flame retardant removal rate, the easiness of removal of the added adsorbent, the coloring of the solution, and the like. As a method of using these inorganic adsorbents, besides a method of directly adding them to a solution, a method of removing the inorganic adsorbent through a solution several times through a column filled with the adsorbent is possible.

Example 3 Next, an experiment was conducted to decompose the removed flame retardant (including the resin) using high-temperature and high-pressure water. FIG. 1 shows a schematic configuration of the decomposition experiment apparatus.

In this decomposition experiment apparatus, water or an aqueous solution composed of water and hydrogen peroxide is sent out from the raw material liquid tank 1 as treated water by the pump 2, passes through the preheater 4 in the preheating unit 3, and has a predetermined temperature. And supplied to the reactor 5 having the temperature control means 6 at a constant flow rate.

The sample to be decomposed is placed in the reactor 5 (volume:
100 cm ³ , material: Inconel), or can be supplied from a raw material liquid tank in a slurry state. The decomposed product is cooled in a cooler together with the aqueous solution and collected. Quantify the amount of organic matter and the amount of halogen in the recovered aqueous solution,
The decomposition characteristics were studied.

194 mg of the removed flame retardant (solid containing resin, flame retardant amount: 10% by weight) is charged into the reactor 5, and an aqueous solution having a hydrogen peroxide concentration of 1.25% is supplied to the reactor 5 at a rate of 20 ml / min. did. The temperature of the aqueous solution is controlled by the heater of the preheater 4 and 238 ° C. in about 50 minutes after the heater is turned on.
Then, the temperature in the reactor 5 increased to 398 ° C. in 114 minutes.

Formula 1 shows the molecular structures of the flame retardant and the resin.
FIG. 2 shows the relationship between the amount of carbon (including carbon dioxide) and the amount of halogen in the aqueous solution and the reaction temperature for the aqueous solution containing the decomposition product sampled from the reactor.

[0060]

Embedded image

As shown in FIG. 2, the flame retardant sample was about 27
From around 0 ° C., the carbon content (TOC, ppm) increases, and it can be seen that the decomposition of the sample starts to occur. The decomposition of halogen (bromine) starts to occur at around 300 ° C. This indicates that the decomposition of the resin component is likely to occur first. As shown in Chemical formula 1, the halogen is bonded to the benzene ring, which indicates that the decomposition of the benzene ring is less likely to occur than the resin. The decomposition of halogen peaked at around 370 ° C., and the total inorganic halogen (here, bromide ion) was 90% of the charged composition.
That is, about 90% of the halogen contained in the flame retardant was decomposed and could be recovered as an inorganic substance. The carbon component was also decomposed into carbon dioxide (about 20%) and the rest to carboxylic acid and benzoic acid. Therefore, it was found that the halogen-based flame retardant can be decomposed with water containing hydrogen peroxide at 270 ° C. or higher.

Here, water was flowed at 20 ml / min.
It is clear that reducing the flow rate of water improves the decomposition rate of organic matter. For example, when flowing at 1 ml, about 80% of organic matter was decomposed into carbon dioxide.

The concentration of hydrogen peroxide depends on the amount of the sample to be charged into the reactor, but decomposition is possible if it is at least the same mole number as the amount of carbon in the sample. This time, the hydrogen peroxide concentration was 1.25%, but the number of moles was about 10 times the mole. Therefore, the effect appears when the concentration of hydrogen peroxide is about 0.1%. Even when the concentration is 5% or more, the molar number is excessively large, and no effect such as improvement in reactivity is observed. In addition, if hydrogen peroxide is added in a large excess, it is of course disadvantageous in terms of cost, but the temperature control and pressure control in the reactor cannot be controlled due to the corrosion of the reactor and the heat generated by the decomposition of hydrogen peroxide. Sometimes. Therefore,
The concentration of hydrogen peroxide is preferably from 0.1 to 5%. As the oxygen source, pressurized air or the like can be used as appropriate.

Example 4 In the same manner as in Example 3, 184 mg of a sample was charged into a reactor, and a hydrogen peroxide concentration of 1.25% and an ammonia concentration of 0.0
Decomposition was performed with a 3% aqueous solution. 75% of the halogen was recovered, and the organic matter was decomposed in the same manner as in Example 3. By adding ammonia, the pH (hydrogen ion concentration) of the aqueous solution becomes alkaline, and the pH after decomposition becomes close to neutral, so that the problem of reactor corrosion is reduced. However, considering the corrosion of the reactor, the pH range of the aqueous solution is
3 to 10, preferably 4 to 9 is good.

[0065] Within this range, there is no particular restriction on the alkali component to be added, and sodium hydroxide, potassium hydroxide, tetramethylammonium hydroxide and the like can be used.

Example 5 The solution containing the flame retardant, resin and the like separated in Example 1 was adjusted to a concentration of 30%, and a single screw extruder capable of vacuum heating (set temperature: 250 ° C., KRC kneader, Kurimoto Iron Works) Was introduced at a feed rate of 20 kg per hour. The extruder has two vents that can be evacuated, and the degree of vacuum is 30 Torr. The solvent component separated by evaporation is
It was condensed by a condenser and recovered as a regenerated solvent. Since a lower alcohol slightly decomposed by the adsorbent is mixed in the regenerated solvent, the alcohol and a solvent such as limonene were separated by distillation as necessary. The composite of the styrene resin and the flame retardant melted in the extruder is extruded in the form of a thread, cooled in a cooling bath, and cut by a pelletizer into regenerated flame retardant pellets. The regenerated flame retardant pellet is appropriately blended with a new styrene resin or the like, and can be reused as a molding material again. 20% recycled flame retardant pellets (amount of flame retardant: 1
Styrene-based molding material containing 0%) has flame retardancy of V-0 grade, and measured mechanical properties such as tensile strength, bending strength, impact strength, and softening point. It was almost equivalent. Comparative Example 1 2% by weight of brominated flame retardant (hexabromocyclododecane)
The waste Styrofoam for building materials contained therein was pelletized by a single-screw extruder heated to about 220 ° C. At the time of heating, decomposition caused by the decomposition products of oxygen and the brominated flame retardant occurred, and the molecular weight was reduced by about 40%, heat resistance was reduced by about 10 ° C., tensile strength was reduced by 20%, and impact strength was reduced by about 30%.

COMPARATIVE EXAMPLE 2 In the same manner as in Example 1, a waste TV cabinet containing 10% by weight of a brominated flame retardant (decabromodiphenyl ether) was added to a DB.
20% by weight was dissolved in E ester (boiling point: 210-225 ° C). The pellet was produced by vacuum heating and devolatilization under the same process conditions as in Example 1 without separating the flame retardant.
0.6% of the residual solvent remained in the regenerated pellets, and the heat resistance was reduced by about 30 ° C. The heating temperature was raised to 260 ° C., and devolatilization was performed, but the residual solvent was not reduced to 0.5% or less. When the heating temperature is 260 ° C., the decomposition of the flame retardant and the thermal deterioration of the resin become severe, the molecular weight is reduced by about 30%, and the yellow color is obtained. Therefore, in order to maintain the properties of the regenerated polystyrene, the heating temperature is 260 ° C. or less, and the boiling point of the solvent is 20 ° C.
It has been found that it is preferable that the temperature is 0 ° C. or less and the amount of the residual flame retardant is 1% by weight or less.

Comparative Example 3 Bromine flame retardant (hexabromocyclododecane) 5% by weight
Styrofoam waste for building materials containing 30 pieces of d-limonene
The liquid in which the weight% was dissolved was separated as it was under the same vacuum heating conditions as in Example 1. The residual solvent is 0.1% or less, but the molecular weight reduction caused by the decomposition product of the brominated flame retardant is about 2%.
0%, and about 2% of impurities in the resin were generated, so that the heat resistance was reduced by about 10 ° C. and the impact strength was reduced by about 30%.

[0069]

As is apparent from the above description, in the process of dissolving and recycling styrene waste containing a flame retardant with an organic solvent, by using a specific adsorbent, the halogen remaining in the solution can be reduced. Can be easily removed (removal rate> 99%). Therefore, after removing the flame retardant, high-quality recycled material can be recycled without causing thermal deterioration of the resin by performing vacuum heating and devolatilization at a temperature of, for example, 260 ° C. or less.

As a method for decomposing the removed halogen-based flame retardant, high-temperature water is effective, and about 90% or more of the halogen can be recovered as an inorganic substance.

Thus, the recycling rate of the styrene waste material containing the flame retardant can be greatly improved, and the resources can be effectively used.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one configuration example of a decomposition experiment apparatus using high-temperature and high-pressure water.

FIG. 2 is a characteristic diagram showing the relationship between the reaction temperature and the amount of carbon TOC and the amount of halogen in an aqueous solution.

[Explanation of symbols]

 1 raw material liquid tank, 4 preheater, 5 reaction vessel

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Noritaka Sato, Inventor 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (72) Inventor Hiroyuki Nagasawa 7-35, Kita-Shinagawa, Shinagawa-ku, Tokyo Sony Corporation F term (reference) 4F301 AA15 AB01 CA09 CA12 CA65

Claims (14)

[Claims] 1. A styrene resin waste containing a flame retardant is dissolved in an organic solvent, and at least one selected from an adsorbent containing lower alkoxide, magnesium oxide and / or aluminum oxide and activated carbon is added to the solution. A method for recycling styrene resin waste material, comprising separating and collecting a styrene resin after adsorbing and removing the flame retardant. 2. The method according to claim 1, wherein the amount of the residual flame retardant in the separated and recovered styrene resin is 1% by weight or less. 3. The organic solvent according to claim 1, wherein the organic solvent has a dissolving power of 15% by weight or more at room temperature in styrene resin, contains no halogen, and has a boiling point of 200 ° C. or less. 2. The method for recycling styrene resin waste according to 1. 4. The method for recycling styrene resin waste material according to claim 1, wherein the organic solvent contains d-limonene as a component. 5. The styrene according to claim 1, wherein the lower alkoxide is at least one selected from sodium methoxide, sodium ethoxide, sodium butoxide, potassium butoxide, magnesium ethoxide, and aluminum propoxide. How to recycle resin waste. 6. The adsorbent according to claim 1, wherein the adsorbent is a magnesium oxide-based hydrotalcite adsorbent.
The recycling method of the styrene resin waste material described in the above. 7. The addition amount of at least one selected from the group consisting of the lower alkoxide, the adsorbent containing magnesium oxide and / or aluminum oxide, and activated carbon is 0.5 to 5;
2. The method for recycling styrene resin waste material according to claim 1, wherein the amount is by weight. 8. The method for recycling styrene resin waste material according to claim 1, wherein insoluble components are removed from said solution in advance. 9. The method for recycling styrene resin waste material according to claim 1, wherein the solution from which the flame retardant has been adsorbed and removed is subjected to vacuum heating and devolatilization to remove and recover the residual organic solvent and separate and recover the styrene resin. . 10. The method for recycling styrene resin waste material according to claim 1, wherein the adsorbed and removed flame retardant is decomposed with treated water at 270 ° C. or higher. 11. The treated water may be a hydrogen peroxide solution of 0.1%.
The method for recycling styrene resin waste material according to claim 10, wherein the content of styrene resin is from 5 to 5% by volume. 12. The method for recycling styrene resin waste according to claim 10, wherein the treated water has a hydrogen ion concentration pH at normal temperature of 4 or more and 10 or less. 13. The method for recycling styrene resin waste according to claim 1, wherein the styrene resin waste is foamed styrene waste containing a flame retardant. 14. The method for recycling styrene resin waste according to claim 1, wherein the styrene resin waste is a high impact styrene cabinet waste containing a flame retardant.