JP2001160243A - Method for treating waste optical recording medium - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for continuously treating waste optical recording media, wherein the waste optical recording media consisting essentially of a polycarbonate resin and having a reflection layer and the like are chemically decomposed and the resultant bisphenolic compound is efficiently recovered without inclusion of foreign matter. SOLUTION: The waste is chemically decomposed in the presence of a solvent, an alcohol and a catalyst in a decomposition vessel 1. After the reflection layer and the light of the decomposition residue are separated and removed in a segregation vessel 3, the bisphenolic compound is recovered in a separation vessel 7 and the residual solution is fed to a distillation tower 11 to fractionate and recover the solvent and alcohol which are circulated to the decomposition vessel 1 for reuse.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for treating optical recording medium waste, and more particularly, to a method for chemically decomposing optical recording medium waste mainly composed of polycarbonate resin to produce a bisphenol-based compound as a chemical raw material. The present invention relates to a method for treating optical recording medium waste that can be recycled.

[0002]

2. Description of the Related Art It is well known that, in recent years, with the increase of waste plastics, the treatment thereof has become a social problem due to lack of landfills and generation of harmful gases during incineration. Therefore, it has become very important to reuse (recycle) the discarded plastic.

[0003] Waste plastic recycling methods are broadly classified into material recycling in which waste plastic is reused as it is, chemical recycling in which waste plastic is depolymerized into monomers, or chemically decomposed into chemical raw materials.
There is thermal recycling to recover as heat energy. For example, as material recycling, a part of a beverage container is collected as a container and reused as a beverage container (return bottle). In addition, polyethylene phthalate (PET) bottles and the like are melt-spun after collection of the bottles, and are reused in clothing and the like as polyester fibers. However, plastics to which such a method can be used are limited, and there are problems such as contamination of impurities and foreign substances, and therefore, they cannot be used for many waste plastics.

[0004] On the other hand, chemical recycling is a recycling method for returning to chemical raw materials, from which synthetic resins and chemical products can be newly synthesized, and have the advantage that they can be used for a wide range of applications. is there.

[0005] Incidentally, polycarbonate resins are widely used as materials for optical recording media. For example, CD
(Compact disc) is typically composed of a substrate made of a polycarbonate resin, and an aluminum reflective layer, an ultraviolet curable resin protective layer, and an auxiliary layer composed of a label print layer made of an ultraviolet curable resin and an inorganic pigment. I have. 99% by weight of the substrate made of polycarbonate resin
Or more. Therefore, the most important thing for recycling the materials used in CDs depends on how the polycarbonate resin can be reused.

Under such circumstances, a method of recycling the resin from an optical recording medium such as a CD has been attempted. For example, Japanese Patent Application Laid-Open No. 6-63942 discloses a method in which an optical recording medium is crushed and then crushed in an acidic solution. Discloses a method of dissolving a reflective layer, separating a protective film layer from a substrate, and collecting a resin used for the substrate. Also, Japanese Patent Laid-Open No. 4-36003
No. 5 and 7-286064 describe a method of crushing an optical recording medium, removing a reflective layer and a protective film layer in a basic solution, and recovering the resin used for the substrate. I have.

[0007]

However, in the methods described in the above-mentioned publications, foreign matters and the like are mixed in the recovered polycarbonate resin, and the use for reuse is limited. In addition, in order to prevent foreign substances from entering, it is necessary to perform quality control in a considerable process. Further, since the substrate used for the optical recording medium has undergone a considerable heat history in the molding process, the recovered polycarbonate resin has problems such as a decrease in physical properties, a decrease in the molecular weight, a coloring, etc. Is restricted.

According to the present invention, a chemical recycling method has an advantage that synthetic resins and chemical products can be newly synthesized as described above and can be used for a wide range of applications.
An optical recording medium waste that can be used to decompose a discarded optical recording medium mainly composed of a polycarbonate resin and having an auxiliary layer such as a reflective layer and to collect a bisphenol-based compound that is a raw material monomer of the polycarbonate resin without mixing foreign substances. It is an object of the present invention to provide a continuous processing method.

[0009]

Means for Solving the Problems The inventors of the present invention focused on the solubility of a polycarbonate resin and its decomposition product and an auxiliary layer such as a reflective layer in a solvent, and conducted intensive studies. The polycarbonate resin is chemically decomposed in a solvent that dissolves the decomposition product but does not dissolve the auxiliary layer, and the remaining auxiliary layer that is not decomposed from the reaction solution is separated by filtration and then decomposed from the solvent solution. The present inventors have found that the object of the present invention can be achieved by continuously recovering the substance and the solvent, and reached the present invention.

That is, the present invention provides (1) a step of chemically decomposing an optical recording medium waste mainly composed of a polycarbonate resin and having an attached layer in an organic solvent in the presence of an alcohol and an alkali catalyst; (1) separating the attached layer from the product mixture, (3) separating and recovering the bisphenol compound produced in step (1) from the remainder of step (2), and (4) removing the bisphenol compound from the remainder of step (3). A method for treating a waste optical recording medium (processing method 1), comprising a step of recovering the organic solvent, the unreacted alcohol, and the carbonic acid diester by-produced in step (1) and contained in the remainder.
Is the gist. Further, the treatment method 1 of the present invention is characterized in that the organic solvent and the unreacted alcohol recovered in the step (4) are circulated to the step (1).

Further, the present invention provides (1) an optical recording medium waste mainly composed of a polycarbonate resin and having an attached layer,
A step of chemically decomposing in an organic solvent in the presence of an alcohol and an alkali catalyst, (2) a step of separating the attached layer from the product mixture of step (1), and (3) a step (1) from the remainder of step (2). Waste light characterized by comprising a step of separating and recovering a bisphenol compound produced and a step of recovering the organic solvent, the unreacted alcohol and the carbonic acid diester by-produced in step (1) and contained in the remainder. The gist is a processing method of a recording medium (processing method 2). Further, the treatment method 2 of the present invention is characterized in that the organic solvent and the unreacted alcohol recovered in the step (3) are circulated to the step (1). In addition, treatment methods 1 and 2 of the present invention
Is characterized in that the accessory layer comprises at least a protective layer, a label printing layer and a reflective layer.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The optical recording medium waste used in the processing methods 1 and 2 of the present invention is mainly composed of a polycarbonate resin and has an attached layer. As an optical recording medium, C
D, CD-ROM, and the like. Such optical recording medium products usually have an auxiliary layer such as a reflective layer, a protective layer, and a label printing layer. The reflective layer is usually made of an alloy thereof such as aluminum, gold and silver, the protective layer is usually made of a crosslinked cured resin, and the label printing layer is usually made of a cured resin and an inorganic pigment. And 2 are insoluble in the solvent used in step (1).

The step (1) according to the processing method 1 of the present invention comprises:
The method comprises chemically decomposing optical recording medium waste mainly composed of polycarbonate resin and having an attached layer in an organic solvent in the presence of an alcohol and an alkali catalyst. Step (1)
As the organic solvent used in benzene, toluene,
Aromatic hydrocarbons such as ethylbenzene and xylene are preferred. The chemical decomposition reaction is a transesterification reaction between a polycarbonate resin and an alcohol, and is performed in the presence of an alkali catalyst. As the alcohol, lower alcohols such as methanol, ethanol, propanol, isopropanol and butanol are preferable. As an alkaline catalyst,
Sodium hydroxide, potassium hydroxide, sodium carbonate,
Alkali metal hydroxides such as potassium carbonate are preferred.

The optical recording medium waste may be used as it is, or may be used after being pulverized. Pulverization is desirable because the reaction proceeds quickly. It is desirable to use an organic solvent in an amount that is sufficient to completely dissolve the bisphenol-based compound obtained by stoichiometric decomposition of the polycarbonate resin. That is, in consideration of the solubility of the obtained bisphenol-based compound at a predetermined temperature, it is desirable to use an organic solvent that is at least as high as to prevent the bisphenol-based compound from being saturated and not being precipitated without being dissolved.

The alcohol is preferably used in a stoichiometric amount which causes a transesterification reaction with the polycarbonate resin, or in an amount not exceeding twice the amount. Further, it is preferable to use the alkali catalyst in a range of 1 to 10 mol% of the amount of the alcohol used. When the decomposition reaction is performed under heating at a temperature not exceeding the boiling point of the organic solvent or alcohol used,
This is desirable because the reaction is carried out efficiently. Step (1) is
It is preferable to carry out the stirring under stirring in order to efficiently contact the waste with an organic solvent or the like.

Step (2) according to the processing method 1 of the present invention comprises:
A solution containing a bisphenol compound produced in step (1) and dissolved in an organic solvent and a diester carbonate which is also by-produced and dissolved in the organic solvent; From the product mixture with the auxiliary layer,
This is a step of separating the accessory layer. The separation of the auxiliary layer is performed by filtration with a filter paper, separation with a fine metal screen, or the like.

Step (3) according to the processing method 1 of the present invention comprises:
This is a step of separating and recovering the bisphenol compound from the remaining solution of the step (2). Since the bisphenol compound has a relatively high melting point, if the solution is cooled to about room temperature, it can be easily precipitated and separated and recovered.
The bisphenol-based compound separated and recovered as described above is composed of a solid substance. However, since the alkali catalyst used in the step (1) may be attached, the alkali catalyst is removed by washing with water as necessary. Is also good. Further, in order to increase the purity, recrystallization may be performed by a known recrystallization method as needed. Step (4) according to the processing method 1 of the present invention includes:
This is a step of recovering the organic solvent, the unreacted alcohol and the carbonic acid diester contained in the remainder of the step (3). These organic solvents, alcohols and carbonic acid diesters are useful as chemical resources, and their recovery is significant. Since these organic solvents, alcohols, and carbonic acid diesters are separated from each other by a boiling point enough to be separated by distillation, they can be easily recovered by distillation and separation. The recovered organic solvent and alcohol are
It can be recycled to the step (1) according to the present invention.

The processing method 2 of the present invention comprises steps (1) to (3). The steps (1) and (2) may be the same as the processing method 1. Step (3) of treatment method 2 involves separating and recovering the bisphenol-based compound and recovering the organic solvent, unreacted alcohol and diester carbonate in this one step, which were performed in two steps in treatment method 1. It is.

Step (3) according to the processing method 2 of the present invention comprises:
In the step (3) according to the treatment method 1, while the remaining solution in the step (2) is cooled to separate and recover only the bisphenol compound, the solution is heated and the bisphenol compound having a high boiling point is heated. The method comprises recovering the organic solvent and the like and separating and recovering the bisphenol compound in the same manner as in the step (4) according to the treatment method 1 by utilizing the large boiling point difference between the organic solvent and the organic solvent. The bisphenol compound separated and recovered in this step (3) and the recovered organic solvent and the like can be handled in the same manner as in the case of the treatment method 1.

Hereinafter, a specific example of the method of the present invention will be described with reference to the drawings. FIG. 1 is a specific example of the processing method 1 of the present invention, and FIG. 2 is a specific example of the processing method 2 of the present invention. As shown in FIG. 1, optical recording medium waste is transferred from a waste storage tank 2 to a solvent,
The alcohol and the alkali catalyst are supplied to the chemical decomposition tank 1 from separate storage tanks (not shown). The chemical decomposition tank 1 is provided with a stirring means (not shown), and the chemical decomposition reaction is performed with stirring. The reaction is continued until the chemical decomposition is completed. The product mixture obtained after the completion of the chemical decomposition is discharged to the separation tank 3, and the auxiliary layer such as the reflection layer in the product mixture is separated by the screen 4 installed in the separation tank 3 and moving continuously. Removed.

While the chemical decomposition reaction is continued in the chemical decomposition tank 1, the separation tank 3 is stopped. To avoid this, a plurality of chemical decomposition tanks 1 are installed, and the optical recording medium waste is disposed. Are successively supplied to cause a chemical decomposition reaction, and a means for sequentially discharging a product mixture obtained by the completion of the chemical decomposition reaction to the separation tank 3 is employed. Can be activated.

The remaining solution obtained by separating the auxiliary layer in the separation tank 3 is cooled in the cooler 6 and then supplied to the separation tank 7.
The bisphenol-based compound which has become supersaturated by being cooled by the cooler 6 and is precipitated is extracted from the bottom of the separation tank 7, washed with water supplied in the washing tank 8, and then washed with water in the separation tank 9. Separated from the resulting alkaline wastewater,
Collected.

The remaining solution from which the bisphenol compound has been separated in the separation tank 7 is heated in the heat exchanger 10 and, if necessary, further heated by a heater (for example, the heater 14 in FIG. 2). The organic solvent, alcohol, and carbonic acid diester supplied to the solution 11 are fractionated and recovered respectively depending on the boiling point difference. FIG. 1 shows alcohol from the top of the distillation column 11, carbonic acid diester from the middle of the column,
This shows a case where organic solvents are respectively recovered from the bottom of the column. The recovered organic solvent, alcohol, and carbonic acid diester are used for respective applications, but the organic solvent and alcohol can be circulated to the chemical decomposition tank 1 and reused as shown in the figure.

FIG. 2 shows a specific example of a method of separating and recovering a bisphenol compound different from that of FIG. In FIG. 1, the remaining solution obtained by separating the adjunct layer in the separation tank 3 is cooled by the cooler 6 and then supplied to the separation tank 7. In FIG. 2, the adjunct layer is separated in the separation tank 3. The remaining solution is heated by the heat exchanger 10 and the heater 14 and then supplied to the distillation column 11.

In the distillation column 11, the organic solvent, alcohol and carbonic acid diester contained in the solution are fractionated and recovered by the boiling point difference as in FIG. 1, but the bisphenol compound contained in the solution is melted. Since it collects at the bottom of the tower in a state, it is extracted from the bottom of the tower to the washing tank 8 and the washing tank 8
Is brought into contact with the water supplied in the above to precipitate as a solid. The solid bisphenol compound is separated and recovered in the separation tank 9 from the alkaline wastewater generated by the water washing. In FIG. 2, alcohol is recovered from the top of the distillation column 11, diester carbonate is recovered from the middle of the column, and organic solvent is recovered from the bottom of the column. The recovered organic solvent, alcohol, and carbonic acid diester are used for respective applications, but the organic solvent and alcohol can be circulated to the chemical decomposition tank 1 and reused as shown in the figure.

[0026]

The present invention employs a method of chemically decomposing optical recording medium waste mainly composed of a polycarbonate resin and having an auxiliary layer such as an aluminum reflective layer without directly separating the auxiliary layer. According to this method, the auxiliary layer can be easily separated and removed, and the bisphenol-based compound generated by chemical decomposition can be recovered without contamination. In the treatment method of the present invention, the above-described chemical decomposition, separation, removal, and recovery can be performed continuously. The recovered bisphenol compound is useful as a chemical resource and can be recycled as the chemical resource.

[Brief description of the drawings]

FIG. 1 is a schematic diagram showing one specific example of the method of the present invention.

FIG. 2 is a schematic diagram showing a specific example of the method of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Chemical decomposition tank 2 Waste storage tank 3 Separation tank 4 Screen 5 Partition wall 6 Cooler 7,9 Separation tank 8 Rinse tank 10 Heat exchanger 11 Distillation tower 12 Condenser 13 Storage tank 14 Heater

Continued on the front page (72) Inventor Teruo Takahashi 3-12-12 Moriyacho, Kanagawa-ku, Yokohama-shi, Kanagawa Prefecture F-term in JVC Co., Ltd. (Reference) 4F301 AA26 CA02 CA09 CA12 CA23 CA26 CA33 CA64 CA65 5D121 GG30

Claims (5)

[Claims] 1. A step of (1) chemically decomposing optical recording medium waste mainly composed of a polycarbonate resin and having an auxiliary layer in an organic solvent in the presence of an alcohol and an alkali catalyst, and (2) producing step (1). Separating the auxiliary layer from the mixture, (3) separating and recovering the bisphenol compound generated in the step (1) from the remainder of the step (2), and (4) removing the organic solvent from the remainder of the step (3). A method for treating a waste optical recording medium, comprising a step of recovering the unreacted alcohol and the carbonic acid diester by-produced in step (1) and contained in the remainder. 2. The method according to claim 1, wherein the organic solvent and the unreacted alcohol recovered in the step (4) are circulated to the step (1). 3. A step of (1) chemically decomposing an optical recording medium waste mainly composed of a polycarbonate resin and having an attached layer in an organic solvent in the presence of an alcohol and an alkali catalyst, and (2) producing the step (1). Separating the adjunct layer from the mixture, and (3) the step (1) from the remainder of the step (2)
Separating and recovering the bisphenol-based compound produced in the step (1), the organic solvent, the unreacted alcohol and the step (1).
Recovering the carbonic diester contained in the residue by-produced in step (a). 4. The method for treating a waste optical recording medium according to claim 3, wherein the organic solvent and the unreacted alcohol recovered in the step (3) are circulated to the step (1). 5. The method for processing a waste optical recording medium according to claim 1, wherein the accessory layer comprises at least a protective layer, a label printing layer, and a reflective layer.