JPH04360035A - Treatment of waste optical disk - Google Patents

Abstract

PURPOSE:To efficiently recover a high-quality polycarbonate resin which can be recycled as a raw material for producing CDs. CONSTITUTION:The waste of the optical disks constituted by providing aluminum reflection films on polycarbonate signal substrates is crushed to 3 to 10mm and the crushed disks are brought into contact with an aq. treating liquid contg. 10 to 30% alkali hydroxide at 75 to 100 deg.C, thereby dissolving or peeling the deposits. The crushed disks are then separated from this treating liquid and are thereafter washed and dried, by which the granular polycarbonate resin is recovered.

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 waste optical discs, particularly compact discs made from polycarbonate resin, to recover high quality polycarbonate resin.

0002

[Prior Art] Compact discs (hereinafter sometimes simply referred to as CDs) are manufactured by forming an aluminum reflective film on a polycarbonate signal substrate by vapor deposition or other film forming methods, and then coating it with a protective coating and printing. Manufactured by When such CDs are damaged or when disposing of inventory, it is undesirable to discard them in their original form, so methods of destroying them and burying them in a landfill or incinerating them are adopted. However, incineration requires an incinerator with a special structure, and destroying and landfilling not only requires processing equipment but also the problem of selecting a landfill site.
Not only does treatment cost increase, but the problem of environmental pollution cannot be ignored.

[0003] Since the amount of CD waste is expected to increase further in the future, if valuable materials can be recovered from this waste, it will be possible to reduce processing costs and further reduce CD manufacturing costs. You can also expect As a means of recovering these valuable materials, there is a method of mechanically scraping the surface of the CD using, for example, a wire brush method or a sandblasting method, but this method has the problem of not being able to prevent wire scraps, shot powder, etc. from being mixed in. be.

[0004] Based on the premise of the presence of these impurities, a method has been proposed in which CDs are crushed as they are and then recycled into pellets by mixing pigments such as carbon black. However, the black pellets thus obtained had the disadvantage of not having sufficient physical properties and being of limited use.

[0005]

[Problems to be Solved by the Invention] The present invention solves the problem of the conventional CD
The purpose of this invention is to provide a method for processing waste CDs that can improve the drawbacks of the recycling method and efficiently recover high-quality polycarbonate resin that can be reused as a raw material for CD manufacturing. .

[0006]

[Means for Solving the Problems] An object of the present invention as described above is to dispose of waste optical discs formed by providing an aluminum reflective film on a polycarbonate signal substrate in a distance of 3 to 10 m.
The deposits are dissolved or peeled off by contacting with an aqueous treatment solution containing 10 to 30% alkali hydroxide at 75 to 100°C, and then separated from the treatment solution, washed with water, and dried to form granules. This can be achieved by a method for processing waste optical discs, which is characterized by recovering polycarbonate resin.

In the treatment method of the present invention, it is necessary to crush the waste CDs in advance to a particle size of 3 to 10 mm. If the crushing is finer than this, not only will there be a problem of dust generation, but the efficiency of washing and drying will be reduced.
The quality of recovered granules is also likely to deteriorate. Furthermore, if the particle size is too coarse, there arises a problem that the reflective film and protective coating tend to be insufficiently removed.

The alkali hydroxide used in the treatment method of the present invention is preferably sodium hydroxide, but other alkali hydroxides such as potassium hydroxide may also be used. When the aqueous treatment liquid containing alkali hydroxide is an aqueous solution of sodium hydroxide, the concentration of sodium hydroxide is preferably about 20%. If the concentration of alkali hydroxide is too low, the processing time will be long and it will not be efficient, and if it is too concentrated, it will not only be difficult to handle but also uneconomical.

[0009] The treatment temperature in the present invention is 75 to 100°C.
However, the temperature is more preferably 80 to 98°C. If the processing temperature is too low, the processing time will be longer and it will not be efficient.
Moreover, there is no particular advantage in setting the temperature at 100° C. or higher.

0010

[Operation] When the crushed polycarbonate material is brought into contact with the aqueous treatment liquid under the above conditions, the aluminum reflective film and the protective paint film are dissolved in the aqueous treatment liquid, and the printed film etc. are also peeled off and removed. Therefore, the crushed polycarbonate separated from the aqueous treatment liquid is cleaned by washing with water and recovered as a highly pure granular polycarbonate resin.

[0011]

EXAMPLES The method for processing waste optical discs according to the present invention will be further explained below based on examples. [Example 1] Waste CDs collected from the market are crushed to produce 5
It was made into a crushed material of about 10 mm. 2 kg of this crushed material was placed in 20 L of a 20% sodium hydroxide aqueous solution at a temperature of 95°C, and stirring was continued for 20 minutes while heating the mixture to a temperature not to fall below 80°C. When the crushed material was then separated from the liquid and washed with water, the aluminum reflective film, protective film, printed film, etc. were all dissolved and removed, and granular polycarbonate resin containing no impurities was recovered.

[Example 2] 20L of 20% sodium hydroxide aqueous solution was put into a Henschel mixer with a capacity of 30L, and after heating it to around 90°C, 2kg of waste CD was added, and the liquid temperature was maintained at 80 to 95°C. Rotating blades at 600rpm
The mixture was coarsely ground by rotating at m for 5 minutes. Then increase the rotation speed to 16
Increase the speed to 00~1800rpm and further increase the speed to 80~95℃ for 15 minutes.
Grinding and processing continued for minutes. Thereafter, the treated product was transferred to a sieving device to separate the treated solution, washed with water, and then dried to obtain recycled polycarbonate resin having a particle size of 3 to 10 mm.

[0013]

Effects of the Invention According to the method for processing waste optical discs of the present invention, high quality recycled polycarbonate resin can be efficiently recovered from waste CDs, resulting in great economic effects.

Claims (2)

[Claims] [Claim 1] The waste of an optical disc formed by providing an aluminum reflective film on a polycarbonate signal substrate,
Crush into 3-10mm pieces and add 10-30% alkali hydroxide.
A waste optical system characterized by dissolving or peeling deposits by contacting with an aqueous treatment solution containing the same at 75 to 100°C, and then separating from the treatment solution, washing with water, and drying to recover granular polycarbonate resin. How to handle disks. 2. The method for treating waste optical discs according to claim 1, wherein the crushed optical discs and the aqueous treatment liquid are brought into contact with each other under stirring.