JP3528897B2 - How to recycle optical discs - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical disk recycling method, and more particularly to a method for separating and recovering a substrate and a reflective film from an optical disk including at least a substrate, a dye layer, a metal reflection film, and a protective film.

[0002]

2. Description of the Related Art An optical disc is a medium that is widely used for recording music, images, information, etc. because it can perform high density recording. Among them, compact discs and optical discs belonging to the family are currently used in large quantities. Against this background, in consideration of the recent dust problem, recycling of optical discs such as compact discs has begun to be considered. Optical disks, which currently dominate the market, are read-only, such as CDs. For example, as shown in FIG. 2, a CD includes an aluminum reflective film 13 and a protective film 1 on a polycarbonate resin substrate 11.
4 is laminated in this order.

Among the optical disk recycling methods that have been proposed so far, there is a method of crushing and molding the disk as it is. However, in this method, the protective film component and the reflective film component are mixed in the molded product. Therefore, the reflective film is not collected, and the molded product is not transparent, so that the molded product can be used only for a limited purpose.

As another method, there is a method in which a disc is immersed in an acid or alkali solution to dissolve the aluminum reflection film, so that the protective film and the substrate are separated and recovered to regenerate the substrate resin. According to this method, since the recycled resin is transparent, it can be reused for a relatively wide range of purposes. However, this method has a problem that it is difficult to collect the reflective film.

[0005]

By the way, recordable optical discs, which are not read-only, are also on the market. There are several types of recordable ones, but the one relevant to the present invention is at least the dye layer 12, the reflective film 13, and the protective film 14 on the substrate 11, as shown in FIG. Is an optical disc of a laminated form, and this type of optical disc generally supports writing only once. It should be noted that the protective film 14 is usually printed with ultraviolet curable ink.

One of such optical disks is called a CD-R. In this CD-R, a substrate of a polycarbonate resin, an organic dye such as a cyanine dye, an additive such as a quencher, a reflective film of gold or silver, and an ultraviolet curable resin such as an acrylic resin (for forming a protective film) are usually used. Is used. Also, two CDs of this form-
A DVD having the structure shown in FIG. 4, in which R is attached with an adhesive or the like.
There is also an optical disc called -R. In this figure, 15 is an adhesive layer. Since expensive gold and silver are used in addition to the substrate in these types of disks, it is also desired to collect the reflective film.

As a method of recovering the reflective film, it is possible to use a liquid that dissolves the reflective film as described above. However, since the reflective film is made of extremely stable gold, only a highly dangerous solution such as aqua regia can be used as a solution for dissolving this. It is possible to burn organic substances such as the substrate and recover only gold by heating the entire disk at high temperature, but the resin of the substrate is not recovered by this method. A method of scraping off the protective film and the reflective film has also been proposed, but in a bonded type disc such as a DVD-R, it is necessary to scrape more than half of it, so it cannot be said to be an efficient recovery method.

Therefore, the present inventor has found that the reflective film and the substrate can be separated and recovered from the disc by using an organic solvent which does not dissolve the substrate resin and dissolves the dye layer in the above optical disc. They have found the present invention and completed the present invention.

[0009]

The present invention provides at least the following:
An optical disk comprising a substrate, a dye layer, a metal reflection film, and a protective film is brought into contact with an organic solvent that dissolves the dye layer and does not dissolve the substrate, thereby dissolving the dye layer and the substrate and a protective film with a reflection film. It is a method of recycling an optical disc, which is characterized in that the optical disc is separated and recovered. The present invention is not limited to the optical disk comprising the substrate 11, the dye layer 12, the reflection film 13 and the protective film 14 as shown in FIG. 3, but also the bonded type optical disk with the adhesive layer 15 as shown in FIG. Intended.

In the optical disc having the structure shown in FIG. 3, it is preferable to damage the protective film 14 and the reflective film 13 to accelerate the permeation of the organic solvent into the inner layer of the optical disc. By doing so, the dye component is rapidly dissolved, so that the peeling of the reflective film-attached protective film from the substrate is promoted. The same effect can be obtained even if the disc itself is crushed and then brought into contact with a solvent. Further, it is desirable to apply an external force to the optical disc during or after contact with the organic solvent, and this accelerates the permeation of the organic solvent into the inner layer of the optical disc. Peeling is promoted. As a mode of applying an external force, a method of stirring an organic solvent in which a disk is immersed, or applying vibration to the organic solvent by ultrasonic waves can be adopted.

Further, according to the present invention, when an optical disk having a substrate made of a polycarbonate resin is processed, the solubility parameter (δ value: SOLUBILITY PARAMETER) as an organic solvent is 10 as apparent from the results of Examples described later.
As described above, it is desirable to use those of 20 or less. When the δ value is within this range, the dye can be dissolved without dissolving the polycarbonate substrate. If the δ value is less than 10, the polycarbonate resin will dissolve, making it difficult to recover the resin. If the δ value exceeds 20, the dye cannot be dissolved, and the substrate and the protective film with a reflection film will not separate. I can't.

Further, in the present invention, it is desirable to recover the metal material by heating the protective film with the reflective film separated by the above method to a temperature not lower than the melting point of the metal material forming the reflective film. Furthermore, as shown in FIG.
In the bonded type optical disk with the adhesive layer 15, it is preferable to separate the substrate and the protective film with a reflective film by a method of crushing the optical disk and then contacting it with a solvent.

[0013]

BEST MODE FOR CARRYING OUT THE INVENTION In the present invention, a disc is brought into contact with an organic solvent (hereinafter sometimes abbreviated as "solvent") which dissolves the dye layer, as it is or after being crushed. In this case, there is no limitation on the state of the disc, and it may be in a defective state, before use, or after use. The method of contact with the solvent is not particularly limited, and examples thereof include a method of immersing the disk in the solvent or a method of spraying the solvent on the disk. The solvent used may be any solvent as long as it dissolves the dye layer and does not dissolve the substrate, and the type thereof is not particularly limited.

The substrate is usually made of a polycarbonate resin. Since this resin is soluble in, for example, an aromatic organic solvent or a chlorinated organic solvent, it is desirable to use a solvent other than these. Examples of such a solvent include ethanol (δ value = 11.2) and methanol (δ value = 12.
9), isopropyl alcohol (δ value = 11.5), n
-Monohydric alcohols such as butanol (δ value = 10.7); polyhydric alcohols such as 1,2-ethylenediol (δ value = 14.7) and glycerin; cellosolve solvents such as methyl cellosolve and ethyl cellosolve; 2 A hydroxyketone solvent such as -hydroxy-2-methyl-3-butanone, 4-hydroxy-2-butanone or diacetone alcohol can be used. As a result, the dye is dissolved and peeling occurs at the interface between the substrate and the reflective film.

Since the dye cannot be dissolved in a hydrocarbon solvent such as hexane (δ value = 7.3) or water (δ value = 21), the object of the present invention cannot be achieved.
Acetone (δ value = 9.3), toluene (δ value = 8.
Even when a general-purpose solvent such as 9), acetonitrile, 2-butanone, or tetrahydrofuran (δ value = 9.1) is used, the dye is dissolved and the above-mentioned peeling occurs, but these solvents do not adhere to the polycarbonate resin of the substrate. Since it permeates, it is difficult to regenerate the substrate resin.

From the above, in the present invention, an effective solvent for an optical disk whose substrate is made of polycarbonate resin has a δ value of 10 or more and 20 or less.
Further, in the present invention, a plurality of kinds of solvents having a δ value within the above range can be mixed and used. Further, it is also possible to use a mixed solution in which a solvent having a δ value in the above range and a solvent having a δ value outside the above range are mixed in an appropriate ratio. For example, the object of the present invention can be achieved by employing a mixed liquid of ethanol and water at an appropriate mixing ratio. In any case, it suffices that the solvent to be used contains a solvent having a δ value within the above range.

Further, when the disk and the solvent are brought into contact with each other without crushing the disk, the solvent permeates through the protective film, so that it takes time for the solvent to permeate into the dye layer and the above-mentioned peeling proceeds efficiently. Absent. In order to avoid this, it is very effective to scratch the protective film side of the disk in advance so that the solvent and the dye layer can come into direct contact with each other. There is no particular limitation on the method of making scratches, and a blade, a heating wire, a laser beam, or the like can be used. There are no particular restrictions on how to make scratches such as depth, arrangement, and number of scratches, but it is preferable that the scratches start on the protective film side and end on the dye layer (the upper end portion or the lower end portion thereof).

Further, when the disc is immersed in a solvent for the above-mentioned peeling (separation of the substrate and the protective film with a reflection film, that is, peeling at the interface between the substrate and the reflection film), the solvent may be stirred and / or heated. Alternatively, a method of applying ultrasonic vibration to the solvent (a solvent stirring / heating / ultrasonic vibration may be used in combination) is possible, which promotes peeling. As a result, the metal material of the reflective film and the substrate resin can be easily recovered.

The peeling between the substrate and the reflection film can be promoted also by rubbing the surface of the dye layer with an appropriate material while the exposed dye layer surface is in contact with the solvent. Specifically, a method of rubbing the surface of the scratched disk with a cloth impregnated with a solvent, or a method of rubbing with a rotating brush while dropping the solvent on the disk surface is employed.

When the peeling between the substrate and the reflection film is promoted by the above-mentioned "rubbing", the material used and its shape are not particularly limited, and examples thereof include metal, plastic, rubber, cloth,
Paper, ceramics, a grindstone, or the like can be used, but these materials are preferably not attacked by the solvent used for peeling. For example, when these materials are dissolved in a solvent, problems such as contamination of the substrate resin may occur.

In addition to polycarbonate resin, PMMA resin (polymethylmethacrylate), PO resin (polyolefin), epoxy resin and the like are used as the substrate material of the optical disk. In the present invention, however, solvent is used also in these cases. A resin that does not dissolve these resins but dissolves the dye is used. Therefore, the type of solvent can be appropriately selected in consideration of the solubility of the dye component and the solubility of the substrate material.

In the present invention, the disc is separated into the substrate resin, the protective film with the reflection film (metal film) and the dye solution by the above treatment. Depending on the peeling conditions, separation may occur between the reflective film and the protective film. For example, ultrasonic vibration is caused by a reflective film
Since the separation between the protective films is promoted, the reflective film and the protective film can be easily separated and collected. The substrate resin separated by the above peeling can be reused as a molding resin by pulverization or the like. The protective film with a reflective film can be separated and recovered by treating the protective film with a solvent or the like that dissolves and disperses the protective film and then filtering the resulting dispersion. Also,
It is also possible to recover the metal of the reflective film by decomposing and vaporizing the protective film component which is an organic substance by performing the high temperature heat treatment. This high-temperature heat treatment method is not particularly limited, and for example, an oven may be used for treatment. The heat treatment temperature is also not particularly limited, and recovery of the metal becomes easier by setting the temperature above the melting point of the reflective film metal.

[0023]

EXAMPLES Examples of the present invention will be described below. Examples 1 to 5 As an optical disc, CD-R: CDQ-74A manufactured by Sony Corp. and having a sectional structure shown in FIG. 3 was used. This disk was obtained by spin-coating a coating solution containing the dye (benzindoline-based perchlorate dye) shown in FIG. 1 on a polycarbonate substrate for CD-R having a diameter of 12 cm, and depositing gold on the coating liquid. It was prepared by spin-coating a UV curable resin as a protective film thereon and then curing this resin layer by irradiating with ultraviolet rays. Then, the following processing was applied to this disc.

Example 1 The above disk was cut into a size of about 2 cm square with a cutter, and this cut product was immersed in a solvent ethanol and stirred for 30 minutes. As a result, the dye began to dissolve in the solvent, and the cut product separated into the substrate resin and the protective film having the gold film (reflection film) attached thereto. The resin was recovered by removing the substrate resin from the solvent. Further, this solvent was filtered to separate the protective film having the gold film attached thereto, which was left in the atmosphere to be dried.

Example 2 As in Example 1, the cut product was immersed in ethanol, and ultrasonic waves were applied to the solvent for 10 minutes. As a result, the dye dissolves in the solvent, the substrate resin, and the protective film with the gold film attached,
Separated into gold dust. The resin was recovered by removing the substrate resin from the solvent. Next, the ethanol solution was filtered to separate and collect the gold powder-attached protective film and the gold powder, which were left to stand in the air and dried.

Example 3 A 1 cm square lattice-like scratch was made on the protective film side of the disk with a razor. Next, while spraying ethanol on the protective film side, it was rubbed with absorbent cotton. As a result, the dye was dissolved, and the protective film with the gold film attached was peeled off from the substrate. After removing the substrate from this ethanol solution, this solution is filtered to obtain a dye solution,
The protective film adhered to the gold film was separated, and the protective film was dried.

Example 4 The dried gold film-adhering protective film recovered in Examples 1 to 3 was heat-treated in an electric furnace at 1200 ° C. for 2 hours. as a result,
The gold for the reflective film could be recovered.

Example 5 Under the same conditions as in Example 1, the possibility of peeling at the interface between the substrate and the reflective film and the effect on the substrate resin were examined for solvents other than ethanol, and the results are shown in Table 1 below. ], [Table 2].

[0029]

[Table 1]

[0030]

[Table 2]

[0031]

As described above, according to the present invention, an optical disk comprising at least a substrate, a dye layer, a metal reflection film and a protective film is contacted with an organic solvent which dissolves the dye layer but does not dissolve the substrate. By performing a simple operation of dissolving the dye layer, the substrate and the protective film with the reflective film can be separated and collected. Further, in the present invention, the protective film and the reflective film are scratched to accelerate the permeation of the organic solvent into the optical disc, whereby the dye component is dissolved, and therefore, the peeling between the substrate and the protective film with the reflective film is performed in a shorter time. It can be carried out. Further, according to the present invention, the peeling between the substrate and the protective film with the reflective film is promoted by applying an external force to the disc during or after the contact between the optical disc and the organic solvent, so that the substrate resin is regenerated and the reflective film is formed. The metal material can be recovered more easily. Furthermore, in the present invention, the solubility parameter of the organic solvent is 10 or more, 20
By using the following, the peeling can be efficiently performed without dissolving the polycarbonate resin which is the substrate material. Further, in the present invention, the expensive protective metal material can be recovered by heating the separated protective film with the reflective film to a temperature equal to or higher than the melting point of the metallic material forming the reflective film.

[Brief description of drawings]

FIG. 1 is a chemical formula of a dye constituting a dye layer of CD-R according to an example of the present invention.

FIG. 2 is a cross-sectional view showing the structure of a conventional CD.

FIG. 3 is a cross-sectional view showing a structure of a conventional CD-R.

FIG. 4 is a sectional view showing the structure of a conventional DVD-R.

[Explanation of symbols]

11 ... Substrate, 12 ... Dye layer, 13 ... Reflective film, 14
...... Protective film, 15 ... Adhesive layer.

─────────────────────────────────────────────────── ─── Continuation of the front page (72) Inventor Naoko Takeda 6-735 Kita-Shinagawa, Shinagawa-ku, Tokyo Within Sony Corporation (56) References JP-A-10-249315 (JP, A) JP-A 9-193156 (JP, A) JP-A-6-306200 (JP, A) US Pat. No. 5306349 (US, A) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29B 17/00 G11B 7 / 26 C08J 11/06 B09B 3/00 B01D 11/02

Claims (5)

(57) [Claims] 1. An optical disk comprising at least a substrate, a dye layer, a metal reflection film, and a protective film is brought into contact with an organic solvent which dissolves the dye layer and does not penetrate into the substrate, thereby dissolving the dye layer and forming a substrate. A method for recycling an optical disk, characterized in that the optical disk is separated and collected into a protective film with a reflective film. 2. The method of recycling an optical disk according to claim 1, wherein the dissolution of the dye layer is accelerated by scratching at least the protective film and the reflective film. 3. The optical disk according to claim 1, wherein an external force is applied to the optical disk during or after the contact with the organic solvent to promote the separation between the substrate and the protective film with a reflective film. Recycling method. 4. When the substrate is made of polycarbonate resin, a solvent having a solubility parameter of 10 or more and 20 or less is used as the organic solvent.
The method for recycling optical discs according to. 5. A method of recovering the metallic material by heating the protective film with a reflective film separated by the method according to claim 1 to a temperature equal to or higher than the melting point of the metallic material forming the reflective film. Characteristic optical disc recycling method.