JP3420016B2 - Resin recovery method - Google Patents

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of recovering a resin as a substrate of an optical information recording medium whose surface is covered with a metal thin film layer or a printed coating layer. More specifically, the present invention provides, from the optical information recording medium,
The present invention relates to a method for selectively removing a metal thin film layer and a printed film layer coated on the surface and collecting the resin component as a substrate for reuse.

[0002]

2. Description of the Related Art Conventionally, a method of reproducing fine sound and unevenness provided on a disk substrate by a laser beam to reproduce sound or an image, a method of recording / reproducing information by an information recording layer provided on the substrate surface, or recording Various optical information recording media have been developed and marketed, such as a method of erasing or overwriting recorded information and a method of laminating these and increasing the recording capacity. Since such an information recording medium is required to have a large amount and a very high density storage capacity and an extremely high quality, the information recording medium must be a defective product even if it has a minute defect. Furthermore, in order to maintain high quality, a large amount of inspection samples must be extracted from various parts of the production process. In particular, reproduction-only compact discs are produced in large quantities, and the treatment of a large amount of resin plates such as samples, defective products, and products collected from the market has become a problem.

Conventionally, such a recording medium has been manufactured by a transparent resin such as a polycarbonate resin, a polymethylmethacrylate resin, an amorphous cyclic polyolefin resin, etc. Among them, the polycarbonate resin is used for most compact discs and can be produced on a large scale. While being carried out, a large amount of samples, defective products, etc. are occurring at the same time. For the processing of these samples and defective products, the transparent optical substrate before applying the information recording layer or the reflective layer is crushed or re-pelletized as it is and mixed with an alloy with general polycarbonate resin or other resin and reused without problems. it can. However, reuse of a resin plate provided with an information recording layer or a reflective layer, and further provided with a protective coat layer such as a UV coat and an adhesive layer for bonding (hereinafter, also referred to as "coated resin plate") Significantly limited. For example, in a UV-coated resin plate, the UV coating layer is incompatible with the polycarbonate resin, so if it is simply mixed with a general polycarbonate resin, the resulting molded product will have irregularities on the surface, and the appearance will be significantly impaired. become. In the case of a laminated resin plate, the heat stability of the adhesive is inferior to that of the resin, so that the hue may deteriorate and the molecular weight of the resin may decrease.

Therefore, it has been proposed to selectively remove the information recording layer, the reflective layer and the protective coating layer from the resin substrate to recover the resin itself. Below, some proposals are explained. (I) Japanese Patent Application Laid-Open No. 4-305414 (European Patent No. 47
6,475, U.S. Pat. No. 5,151,452), JP-A-5-200379 (European Patent No. 537,567).
No. 5,214,072) and JP-A-6-
No. 223416 (European Patent No. 601,719, US Pat. No. 5,306,349): These methods are methods of chemically treating a coated resin plate with, for example, an acid or alkali aqueous solution. . That is, these methods are performed by melting the metal part of the information recording layer or the reflective layer.
It is a method of removing the V coat layer and the label printing layer, and has a drawback that the layer cannot be removed such as a portion having no metal part, a defective resin plate subjected to a coat test, a label printing test, etc. An increase in running cost was unavoidable due to the need for neutralization treatment and drainage neutralization processes.

(Ii) JP-A-5-345321:
This method is a method of immersing the coated resin plate in hot water for a long time, and is excellent in that the neutralization treatment in the above method is not required. However, this method is disadvantageous in that the molecular weight and whitening easily occur in the case of a polycarbonate resin substrate because it is immersed in hot water for a long time, and it is not a preferable method for reusing the recovered resin.

(Iii) Japanese Unexamined Patent Publication No. 5-210873 and US Pat. No. 5,203,067: These methods use a cutting tool or an abrasive mechanically on the surface of the coating layer of the coated resin plate. It is a method of cutting and polishing to remove it.
Since these methods require a device for reading the cutting surface and a device for inverting the surface of the resin plate, the initial investment amount becomes large, and there are disadvantages such as the resin recovery rate due to cutting, making it difficult to spread. there were. Further, as a recent technique, a technique for laminating thin resin plates has been developed for the purpose of increasing the recording capacity, but a new problem arises that grinding cannot be performed because the resin portion is on the outside.

[0007]

The above-mentioned method of recovering the resin from the coated resin plate cannot be said to be an economically and industrially satisfactory method, and from the viewpoint of resin reuse, the quality and It was difficult to understand the recovery rate. Especially when the resin molded product to be reused is required to have transparency and high quality, the conventional method has been unsuitable. None of these conventionally proposed methods is practical, and therefore, most of the resin plate by sampling, the resin plate as a defective product, and the recovered resin plate are treated as industrial wastes. This is a big problem when the number of formula information recording media is increased. In particular, it is a serious problem from the viewpoint of effective utilization of resources and conservation of the global environment.

Therefore, a first object of the present invention is to provide an industrially advantageous method capable of effectively removing a coating layer from an optical information recording medium and selectively recovering a resin component. . A second object of the present invention is to provide a method capable of recovering from an optical information recording medium without substantially deteriorating the quality of the resin of the substrate thereof, and substantially without containing a coating layer. It is in. A third object of the present invention is to provide a method for separating each of a resin component and a coating layer component from an optical information recording medium by a method that does not cause pollution and is useful for environmental protection. A fourth object of the present invention is to provide a method capable of recovering a large amount of resin components from an optical information recording medium in a compact device, particularly a continuous method. Another object of the present invention is to provide a method of recovering a resin from an optical information recording medium and reusing the resin.

[0009]

According to the studies by the present inventors, the object of the present invention is to provide a metal thin film layer, a printed coating layer or a metal thin film and a printed coating on at least one side of a resin substrate. In recovering the resin from the optical information recording medium coated with the layer (1), the following step (1) rolling the recording medium by passing it between at least one pair of rollers (step A), (2) ) A step of bringing the rolled recording medium into contact with heated water (step B), (3) a step of separating a substantial amount of the coating film peeled from the recording medium (step C), (4) the obtained recording medium. Pulverizing step (step D), (5) contacting the obtained recording medium strip with heated water to remove the metal thin film component (step E) and (6) heating the removed metal thin film component Separated from strips with water, collected strips,
It was found to be achieved by a method of recovering a resin, which is characterized by comprising a step of obtaining (step F). Hereinafter, the method of the present invention will be described in more detail.

In the method of the present invention, the optical information recording medium targeted for the recovery of the resin uses a resin capable of transmitting infrared light or visible light as the material of the substrate, and such resin is a dye. And the like, which are colored in black, gold or the like, and have a coating layer on one side of the resin or in the central portion of the laminated sandwich structure. As described above, the resin having the coating layer may be obtained as a sample for inspection or a defective product in the manufacturing process, or may be recovered as a product. Further, as a part, a resin substrate having no coating layer may be mixed. The thickness of such a resin substrate is not particularly limited as long as it is usually used as a recording medium, but is generally in the range of 0.5 to 3 mm, preferably 0.6 to 2 mm. Further, in the case of the bonded resin substrates, there is no limitation as long as the total thickness is within the above range. The shape of the resin substrate is preferably a disk-shaped flat plate molded by injection molding, and can be directly used for the recovery method of the present invention. On the surface of a resin substrate used as a recording medium, a metal thin film such as aluminum, Te, Fe, Co, Gd, SiN, ZnS-SiO is usually used.
₂ , GeSbTe, ZnS, aluminum alloys, etc., with aluminum being suitable. The metal thin film can be formed by means such as sputtering and vapor deposition. Generally, this metal thin film has a thickness of 0.04 to 2 μm, and the surface of the metal thin film is covered with a protective film. As the protective film, a UV coating film of acrylic resin is usually used and has a thickness of 5 to 10 μm. Further, a printed coating layer is formed on the resin substrate directly or on the metal thin film. This printed coating layer is generally called label printing, and the printed coating layer is generally 5
It has a thickness of -30 μm, preferably 10-25 μm. As the coating film forming this printing layer, for example, acrylic paint, acrylic-vinyl paint, vinyl paint, polyester paint, melamine paint, epoxy paint and urethane paint are used. In addition, examples of the adhesive for bonding the two resin plates include acrylic, epoxy, and urethane adhesives, which are used as an ultraviolet curable type or a hot melt type.

In the present invention, as described above, the metal thin film layer (including the protective coating layer thereon), the printed coating layer or the layer of the metal thin film and the printed coating layer is formed on the resin substrate. What is covered by this is the target of collection. According to the present invention, the resin component can be selectively recovered by substantially removing the coating layer from such a coated resin substrate. Hereinafter, in the present invention, the substrate in the information recording medium having the coating layer formed thereon and the substrate having the coating layer removed may be collectively referred to as "resin substrate". Also,
The crushed pieces of the substrates are sometimes referred to as “substrate strips”.

Specific examples of the coated resin substrate include ROM discs such as compact discs, mini discs, and laser discs in the read-only system, and CD-R and write in the recording and reproducing system. There is a DRAM disc such as a once disc, and the rewritable discs include an E-DRAW optical disc such as a magneto-optical disc and a phase change optical disc. These optical disks include a single-sided storage type and a recently developed double-bonded type for DVD. In particular, the method of the present invention selectively selects a resin component from a recording medium, preferably a compact disc and a DVD, on which an aluminum thin film layer is formed as a metal thin film layer and a printed coating film layer is formed on a part thereof. It is an excellent way to recover.
The material forming the substrate of the resin plate may be a light transmissive resin. Usually, polycarbonate resin, polymethylmethacrylate resin, amorphous cyclic polyolefin resin and the like are used. Among them, polycarbonate resin or polymethylmethacrylate resin is preferable, but polycarbonate resin is most preferable.

The above-mentioned polycarbonate resin may be one that is usually used as a thermoplastic aromatic polycarbonate resin molded product, and is generally produced by reacting a dihydric phenol with a carbonate precursor by a solution method or a melting method, The one obtained by any method can be similarly used.

Typical examples of the dihydric phenol used for the production of the aromatic polycarbonate resin include hydroquinone, resorcinol, 4,4'-dihydroxydiphenyl, bis (4-hydroxyphenyl) methane,
1,1-bis- (4-hydroxyphenyl) ethane, 2,
2-bis- (4-hydroxyphenyl) propane [commonly called bisphenol A], 2,4-bis- (4-hydroxyphenyl) -2-methylbutane, 1,1-bis- (4-
Hydroxyphenyl) -cyclohexane, 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, α, α′-bis- (4-hydroxyphenyl) -o-diisopropylbenzene, α, α '-Bis- (4-hydroxyphenyl) -m-diisopropylbenzene, α, α'-bis- (4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis-
(3-methyl-4-hydroxyphenyl) -propane,
2,2-bis- (3-chloro-4-hydroxyphenyl) -propane, bis- (3,5-dimethyl-4-hydroxyphenyl) -methane, 2,2-bis- (3,5-dimethyl-4) -Hydroxyphenyl) -propane, 2,4
-Bis- (3,5-dimethyl-4-hydroxyphenyl) -2-methylbutane, 1,1-bis- (3,5-dimethyl-4-hydroxyphenyl) -cyclohexane,
1,1-bis- (3,5-dimethyl-4-hydroxyphenyl) -3,3,5-trimethylcyclohexane, α,
α'-bis- (3,5-dimethyl-4-hydroxyphenyl) -o-diisopropylbenzene, α, α'-bis- (3,5-dimethyl-4-hydroxyphenyl) -m
-Diisopropylbenzene, α, α'-bis- (3,5-
Dimethyl-4-hydroxyphenyl) -p-diisopropylbenzene, 2,2-bis- (3,5-dichloro-4-)
Hydroxyphenyl) -propane, 2,2-bis- (3,
5-dibromo-4-hydroxyphenyl) -propane,
Bis- (4-hydroxyphenyl) -sulfone, bis-
(4-hydroxyphenyl) -sulfide, bis-
(4-hydroxyphenyl) -ether, bis- (4-
Examples thereof include hydroxyphenyl) -ketone and bis- (4-hydroxyphenyl) -sulfoxide, which may be used alone or in combination of two or more.

Among them, homopolymers of bisphenol A and bisphenol A, 1,1-bis- (4-hydroxyphenyl) -cyclohexane, 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethyl. Cyclohexane, α, α′-bis- (4-hydroxyphenyl) -m
-Diisopropylbenzene, 2,2-bis- (3-methyl-4-hydroxyphenyl) -propane, 2,2-bis- (3,5-dimethyl-4-hydroxyphenyl)-
Propane, 2,2-bis- (3,5-dichloro-4-hydroxyphenyl) -propane and 2,2-bis- (3,
Copolymer obtained from at least two bisphenols selected from 5-dibromo-4-hydroxyphenyl) -propane, especially 1,1-bis- (4-hydroxyphenyl) -3,3,5-trimethylcyclohexane And bisphenol A, α, α′-bis- (4-hydroxyphenyl) -m-diisopropylbenzene or 2,2-
A copolymer with bis- (3-methyl-4-hydroxyphenyl) -propane is preferably used.

Examples of the carbonate precursor include carbonyl halide, carbonate ester, haloformate, and the like, and specific examples thereof include phosgene, diphenyl carbonate, dihaloformate of dihydric phenol, and a mixture thereof. In producing the polycarbonate resin, an appropriate molecular weight modifier, a branching agent, a catalyst for accelerating the reaction and the like can also be used according to a usual method. 2 of the aromatic polycarbonate resin thus obtained
Mixing seeds or more is not a problem.

The polymethylmethacrylate resin is a resin obtained by polymerizing a methylmethacrylate monomer as a main raw material. For optical applications, usually a homopolymer is used, but other copolymerizable monomers, specifically methyl acrylate, ethyl acrylate,
Acrylic acid esters such as propyl acrylate and butyl acrylate and methacrylic acid esters such as ethyl methacrylate, propyl methacrylate and butyl methacrylate
Those obtained by copolymerizing 0 mol% or less can also be used. The polymerization method is not particularly limited, and a production method such as bulk polymerization, suspension polymerization, solution polymerization or emulsion polymerization may be used.

Examples of the amorphous cyclic polyolefin resin include hydrogenated products of ring-opening polymers of norbornene-based monomers. Examples of such norbornene-based monomers include norbornene, dimethanooctahydronaphthalene, trimethanododecahydroanthracene and their alkyl-substituted or alkylidene-substituted compounds,
Examples thereof include dicyclopentadiene, 2,3-dihydrodicyclopentadiene, dimethanooctahydrobenzoindene, dimethanodecahydrobenzoindene, dimethanodecahydrofluorene and alkyl-substituted products thereof. Further, it may have a polar substituent such as a halogen atom, an ester type residue, an ether type residue and a cyano group. Among these, bifunctional or higher
Injection molding becomes difficult, and monofunctional ones are preferably used. These norbornene-based monomers may be used alone or in combination of two or more.

Further, as a copolymerization component, other cycloolefins such as cyclopropene, cyclobutene, cyclopentene, cycloheptene, cyclooctene, 5,6
-Dihydrodicyclopentadiene and the like can be used usually in the range of 30% by weight or less. Further, as the molecular weight modifier, an acyclic olefin may be used, and among them,
Particularly α-, such as 1-butene, 1-pentene, 1-hexene
Olefin is preferred. The ring-opening polymer of the norbornene-based monomer is produced by a usual method for polymerizing norbornenes, but it is preferable to use a well-known metathesis catalyst as the polymerization catalyst. As the metathesis catalyst, a catalyst system containing a transition metal compound such as titanium tetrahalide and an organic metal such as an organoaluminum compound or a catalyst system in which a third component such as an aliphatic or aromatic tertiary amine is combined is preferable. .

The ring-opening polymerization can be carried out without using a solvent, but it is usually an aromatic hydrocarbon such as benzene, toluene or xylene, an aliphatic hydrocarbon such as hexane or heptane, or an alicyclic carbonization such as cyclohexane. It is carried out in an inert organic solvent such as hydrogen or a halogenated hydrocarbon such as dichloroethane. Further, the polymerization temperature is usually selected in the range of -20 ° C to 100 ° C, and the polymerization pressure is selected in the range of 0 to 50 kg / cm ² . The ring-opened polymer of the norbornene-based monomer preferably has Tg of 120 to 200 ° C. in order to use the hydrogenated product as a material for the transparent optical substrate.

The hydrogenated product of the ring-opening polymer of the norbornene-based monomer is produced by using a well-known hydrogenation catalyst. As the hydrogenation catalyst, any of those generally used for hydrogenating olefin compounds can be used. For example, a Wilkinson complex, cobalt acetate /
Examples include triethylaluminum, nickel acetylacetonate / triisobutylaluminum, palladium-carbon, ruthenium-carbon, nickel-diatomaceous earth and the like. The hydrogenation reaction is a homogeneous system or a heterogeneous system depending on the type of catalyst, under a hydrogen pressure of 1 to 200 atm.
It is carried out at 0 to 250 ° C. The hydrogenation rate is
From the viewpoint of light resistance and the like, 95% or more is preferable, and
% Or more is particularly preferable.

Further, addition polymers of norbornene-based monomers are also mentioned as examples of amorphous cyclic polyolefin resins, and homopolymers of norbornene-based monomers are also used, but copolymers obtained by copolymerizing ethylene are preferably used. To be done. As the norbornene-based monomer, the same ones as described above are used. In the present invention, the above-mentioned coated resin substrate can be removed and separated from the resin substrate as it is by the following steps A to F, and the resin component can be isolated and recovered. Each step will be described below.

Step A: This step is a step of rolling the coated resin substrate by passing it between at least one pair of rollers. In this rolling step, the length of the resin substrate rolled by the roller is 1.08 to 2.0 times, preferably 1.1 to 1.8 times, the original length. The gap between the pair of rollers is 0.05 to 0.8 times, preferably 0.1 to 0.7 times, the original thickness of the resin substrate so that the resin substrate is rolled in the above range. Is desirable. At this time, the temperature of the roller is 30 to 14
It is desirable to maintain a temperature of 0 ° C, preferably 60-130 ° C. The rollers may be one pair or a few pairs. It can also be passed several times using a pair of rollers.

The rotation directions of the pair of rollers are usually different from each other, and the two rollers may rotate at the same circumferential speed or may have different circumferential speeds. In this case, the difference between the circumferential velocities may be about 1.05 to 2 times as large as that of the circumferential velocities having a low velocity. However, in the step A of the present invention, the difference in circumferential speed between the pair of rollers is not particularly required and may be substantially the same. However, if the circumferential speeds of the pair of rollers are made different, shearing may occur more easily, which may be advantageous.
Although not particularly limited, the opposing roller gap is 0.1 to 0.1.
At 7 mm, the peripheral speed difference is preferably 1 cm / sec or more. Particularly preferably 3 to 10 cm / sec, 15 cm / s
If it exceeds ec, an extreme warp phenomenon occurs, and subsequent handling becomes difficult, which is not preferable. Although it is advantageous that the number of times of rolling is large, in most cases, the effect can be sufficiently obtained by rolling several times, but it is advantageous that rolling is performed not only in a single direction but in multiple directions because peeling is easy. . Further, heating the roller to keep the surface temperature below the glass transition temperature of the resin is advantageous in that the pressure during rolling is reduced and the mechanical life is extended.

The roller used may be one that is industrially used, and basically no special one is required as long as it is a material that is harder than the resin substrate and does not deform. For example, steel material, plated steel, stainless steel, etc. may be mentioned. Among them, stainless steel is preferable in terms of rust prevention. The surface of the roller may be a mirror surface, a pear-textured surface, or other uneven processing, but a mirror surface is usually used. In the step A, it is necessary to roll the resin substrate and roll it in the length direction thereof, and it is not particularly necessary to apply stress to the surface of the resin substrate, particularly the coating layer and the resin substrate.

Step B: The resin substrate obtained in the step A (hereinafter sometimes referred to as “rolled resin substrate”) is
Contacted with heated water. This process B does not require a special device or chemicals, uses a container (or tank) of an appropriate size, and uses heated water. In the step B, the rolled resin substrate obtained in the step A is brought into contact with heated water, distortion occurs between the coating layer and the resin substrate, and the coating layer, especially the printed coating layer is easily peeled off. Become. Therefore, it is preferable to flow the resin substrate and the heated water in the container such that the heated water and the rolled resin substrate are effectively in contact with each other and the resin substrates are intertwined with each other. When the resin substrates come into contact with each other and are repeatedly detached from each other, the printed coating film is more easily peeled from the substrate. At that time, peeling is also promoted by the action of heated water.

The temperature of the heated water is preferably in the range of 50 to 100 ° C, particularly preferably in the range of 70 to 95 ° C. When the temperature of the heated water is lower than 50 ° C., the time becomes long and the printed coating film cannot be effectively peeled off. On the other hand, if the temperature of the heated water exceeds 100 ° C, pressurization is required, so
Not only is the device complicated and expensive, but it also causes deterioration of the resin, which is not desirable. The contact time between the heated water and the resin substrate in step B is usually 3 to
A practical range is 60 minutes, preferably 5 to 30 minutes.

Although water alone is sufficient as a component of the heated water, another solvent which does not dissolve the resin and is soluble in water is used.
It may be contained in an amount of not more than 10% by weight, preferably not more than 10% by weight. Examples of such a solvent include alcohol, glycol, and ketone. When the resin is an aromatic polycarbonate, alcohol is preferable.
As described above, the process B is carried out in an apparatus in which the resin substrates are repeatedly separated from each other and the heated water and the resin substrates are in contact with each other. Specifically, a method is used in which a resin substrate and heated water are put in a container, and the resin substrates are separated from each other in the container and stirred so as to come into contact with the heated water or the container is rotated. .

In the container in which the process B is carried out, the resin substrate and the heated water can be effectively separated from each other by setting the ratio within an appropriate range. If too much heated water is used, the resin substrates will not be effectively separated from each other, and the contact will not be performed sufficiently. The preferable range is that the weight of the substrate is 0.1 with respect to the total of both.
˜30% by weight, particularly preferably 0.5 to 15% by weight. Most preferred is the range of 1 to 10% by weight.

Further, a container is equipped with a rotary drum, the resin substrate and heated water are put in the drum, and the drum is rotated to repeat the detachment and attachment of the resin substrates.
In addition, the method of bringing the resin substrate into contact with the heated water is a preferred embodiment. At this time, it is suitable that the rotary drum has a large number of pores on its side wall. The pores in the rotating drum help to separate the strips of the stripped printed coating with the heated water out of the drum.

The use of the rotating drum is also very effective for the continuous operation of process B. That is, the rotating drum is installed in a container having heated water, the resin substrate is supplied from one end of the rotating drum, and the resin substrates are separated from each other in the presence of the heated water in the rotating drum, The peeled strips of the printed coating film were discharged from the drum together with heated water through a large number of pores provided on the side wall of the drum, while the resin substrate from which the printed coating film was substantially removed from the other end of the rotary drum was removed. The method of taking out is preferable.

The rotary drum preferably has an internal structure in which the supplied resin substrate moves slowly from one end to the other end as it rotates. As such a structure, a structure in which a spiral partition plate is provided inside the drum is preferable. Further, the drum may be provided with some areas so that the resin substrate may stay in a certain amount and then move to the next area, and a weir may be provided between the areas. The rotary drum may be a vertical type, a horizontal type, or an inclined type, but a horizontal type or a gently inclined type is advantageous. Further, the strips of the printed coating film discharged from the pores of the side wall of the rotary drum can be taken out of the container together with the heated water, the strips can be filtered off, and the heated water can be returned to the container for use. Thus, a small amount of heated water can be circulated and heat loss can be reduced.

Step C: In the step B, the printed coating film applied to the surface of the resin substrate is substantially peeled off, and the coating film becomes a piece and is separated in the heated water. The step C is a step of separating the coating film strip separated from the substrate. This process C does not require a special device. That is, the coating film strips separated from the substrate can be separated by putting a large amount of water or heated water in a container and stirring. It can be separated by dispersing the coating film strip in water or heated water and taking it out of the container. Also, if necessary, water or heated water may be further added, and the coating film strips can be separated and removed by showering the substrate with water or heated water.

This step C can be carried out in the same apparatus (container) as step B, and it is more advantageous. That is, it is advantageous to carry out the contact of the resin substrate with the heated water (step B) and the separation of the stripped coating film pieces (step C) in one container, and it is particularly preferable to carry out these steps in one step. Preference is given to a method which is carried out continuously in a vessel. One of the continuous methods is, as described in the step B, using an apparatus in which a rotating drum is installed in a container, performing the step B, and peeling through the pores provided in the side wall of the rotating drum. Drain the coated film strips with the heated water out of the drum,
Then, the strip C is taken out of the container together with the heated water to carry out the step C. The method using the rotating drum is preferable because the step B and the step C can be easily performed continuously, and a large amount of resin substrates can be processed.

Step D: By the step C, a resin substrate from which the coating film layer has been substantially peeled and removed is obtained. In the case of a compact disc, an elliptical disc which is rolled in the process A and has a separated coating layer is obtained. The step D is a step of crushing the rolled resin substrate. If coating film strips are present when the resin substrate is crushed, they may adhere to the resin substrate again, so it is advantageous to remove the stripped coating film strips as much as possible.

The means for crushing the resin substrate in step D is
There is no particular limitation, and ordinary crushing means for plastic plates is adopted. An example thereof is a method of using a cutting type or hammer type crusher, and a cutting type crusher is preferably used because the amount of fine powder generated is small.
Among them, a crusher having a rotating rotary blade and a fixed blade and a circular hole screen provided at the bottom is preferably adopted, and by using this, a fine resin substrate capable of passing through the screen with less fine powder from the resin substrate is used. Only one piece can be obtained. The crushed pieces of the resin substrate may be uniform in shape or size, or may be random. It is suitable that the size thereof substantially passes through a circular hole having a diameter of 15 mm and 90% by weight thereof does not pass through a circular hole having a diameter of 2 mm. If the size of the resin substrate strip is larger than the above range, it becomes difficult to effectively remove the metal thin film component in the next step E, while if the strip is too small, the grinding process becomes complicated. In addition, handling of the resulting fine powder particles is troublesome, which is not preferable.

Step E: The strip of the resin substrate obtained in Step D is brought into contact with heated water in Step E to remove the metal thin film component coated on the surface of the substrate. This process E does not require a special device or medicine and uses a container (or tank) of an appropriate size and uses heated water. In this E step, heated water is brought into contact with the substrate strip obtained in the D step to remove the metal thin film component on the substrate surface, but the residual coating that could not be removed during the A to D steps. The film layer is also almost completely removed in this E step. for that reason,
It is preferable to cause the substrate strip and the heated water to flow in an appropriate ratio in the container so that the heated water and the substrate strip are effectively in contact with each other and the substrate strips are intertwined with each other.
The metal thin film components are easily removed from the substrate by the substrate strips coming into contact with each other and repeating the detachment. Further, the action of the heated water further promotes the removal.

The temperature of the heated water in step E is 50 to 100 ° C.
Is preferable, and a range of 70 to 95 ° C. is particularly preferable. If the temperature of the heated water is lower than 50 ° C, the time required to remove the metal thin film component tends to be long. On the other hand, when the heating temperature exceeds 100 ° C., pressurization is required, which complicates the apparatus and increases the cost, and also causes deterioration of the resin. The contact time between the substrate strip and the heated water in step E is usually 10 to 60 minutes, preferably 20 to
A range of 40 minutes is practical. As a component of heated water,
Although water alone is sufficient, it may contain 20% by weight or less, preferably 10% by weight or less of another solvent which does not dissolve the resin and is soluble in water. As such a solvent,
Alcohol, glycol or ketone,
When the resin is an aromatic polycarbonate, it is preferably alcohol.

Process E is carried out in an apparatus in which the substrate strips are repeatedly separated from each other and the heated water and the substrate strips are in contact with each other. Specifically, a substrate strip and heated water are placed in a container, and the substrate strips are separated from each other in this container,
A method of stirring or rotating the container so as to come into contact with the heated water is adopted. By setting the ratio of the substrate strip and the heated water within an appropriate range in the container in which the step E is performed, the substrate strips can be effectively separated from each other. If too much heated water is used, the substrate strips will not effectively separate and contact will not be adequate. The preferred ratio is that the weight of the substrate strip is 1 to the total of both.
It is in the range of 50% by weight, preferably 2 to 30% by weight, particularly preferably 3 to 20% by weight.

Further, a rotary drum is provided in the container, the substrate strip and the heated water are put in the drum, and the heated water and the substrate strip are separated from each other by rotating the drum to separate the substrate strip from each other. The method of contacting is a preferred embodiment. At that time, it is suitable that the rotary drum has a large number of pores on its side wall. The pores on the side wall of the rotating drum help the removed metal thin film component to separate out of the drum together with the heated water. The use of the rotating drum is also very effective for continuous operation of the E process. That is, a rotating drum is installed in a container having heated water, substrate strips are supplied from one end of the rotating drum, and substrate strips are separated from each other in the presence of heated water in a rotating drum. Meanwhile, the separated metal thin film component was discharged together with the heated water from the pores provided in the side wall of the drum, and the substrate from which the metal thin film component and the coating layer were removed was continuously supplied from the other end of the rotating drum. The method of taking out is preferable.

The rotary drum preferably has an internal structure such that the supplied substrate strip moves slowly from one end to the other as it rotates. As such a structure, a structure in which a spiral partition plate is provided inside the drum is preferable. The rotary drum may be a vertical type, a horizontal type, or an inclined type, but a horizontal type or a gently inclined type is advantageous. Further, the metal thin film component discharged from the pores on the side wall of the rotary drum can be taken out of the container together with the heated water, the solid component can be filtered off, and the heated water can be returned to the container again for use. Thus, a small amount of heated water can be circulated and heat loss can be reduced.

When the metal thin film on the surface of the resin substrate is aluminum, most of the aluminum thin film is probably dissolved in the heated water as aluminum hydroxide and removed as a solution in this E step.
After the aluminum thin film on the substrate is peeled off, it is not clear whether it dissolves in heated water, is removed while dissolving, or occurs in parallel, but as a result, the metal thin film becomes almost Certainly, a completely removed substrate is obtained. It is presumed by the inventors of the present invention that it is considered that the dissolution of the metal aluminum thin film in the heated water has partially occurred even in the step B.

Step F: In this Step F, the metal thin film component and the remaining coating film component separated in the above Step E are separated from the substrate strip along with heated water, and the strip is collected and obtained as a resin component. is there. This F process does not require a special device. That is, the metal thin film component separated from the substrate strip can be easily separated from the substrate strip together with the heated water. If necessary, after the step E, water or heated water may be further added to separate the strips of the substrate. Further, the metal thin film components can be separated by showering the substrate strip with water or heated water. This step F can be carried out in the same apparatus (container) as step E, which is more advantageous. That is, it is advantageous to use a method in which one of the steps of contacting the substrate strip with heated water (step E) and separating the removed metal thin film component (step F) in one container is carried out, and particularly preferably these steps are carried out. Preference is given to a method which is carried out continuously in one vessel. One of the continuous methods is, as described in the step E, using an apparatus in which a rotating drum is installed in a container, and performing the step E,
The metal thin film component separated through the pores provided on the side wall of the rotating drum was discharged to the outside of the drum together with the heated water,
Then, the F step is carried out by taking out the metal thin film component together with the heated water from the container. This method using a rotating drum is preferable because it is possible to easily carry out the steps E and F continuously, and moreover, a large amount of substrate strips can be processed. The above-mentioned A step, B step, C step, D step, E step and F of the present invention
The steps can be carried out continuously, which is industrially advantageous. By the steps A to F of the present invention described above, the coating layer can be selectively and efficiently removed from the optical information recording medium coated with the metal thin film and the printed coating layer, and the resin substrate has a high recovery rate. Moreover, it is possible to collect with little deterioration of physical properties. Particularly, in the steps A to F of the present invention, the method is simple and a complicated apparatus is not required, and a large amount of resin substrates can be processed with a small apparatus.

According to the research conducted by the present inventors, it has been found that a combination of the following steps is excellent as an industrial process of the method of the present invention. That is, in recovering the resin from an optical information recording medium in which a metal thin film layer, a printed coating layer or a layer of a metal thin film and a printed coating is coated on at least one surface of a resin substrate, the following steps are taken. (1) The recording medium is supplied between at least one pair of rollers and rolled (step A), and (2) the rolled recording medium is fed to one end of a rotary drum having pores, The recording medium is brought into contact with heated water while being entangled with each other in the rotating drum (step B), and (3) the substantial amount of the coating film peeled from the recording medium is separated from the pores of the rotating drum, and the other side of the rotating drum is used. The recording medium is taken out from the end portion of step (step C), (4) the obtained recording medium is crushed (step D), and (5) a small piece of the recording medium is attached to one end of the rotary drum having pores. And contact the strip with heated water in the rotating drum (Step E (6) The metal thin film component removed from the pores of the rotary drum is separated together with heated water, and a strip is taken out from the other end of the rotary drum (step F). is there.

The resin substrate strips recovered according to the present invention do not contain a coating layer, their quality is hardly deteriorated, and they can be directly melted and reused. Further, it can be used as a mixture with the same type of resin, or can be used as a blend with another resin. For example, in the case of a resin substrate of a polycarbonate resin, the recovered resin substrate strip can be used as it is, or can be reused by mixing it with the same polycarbonate resin or another polycarbonate resin of a different type and reusing it. Also, AB
A molded product can be obtained by mixing with a thermoplastic resin such as S resin or polyester resin and reusing it.

[0046]

EXAMPLES The present invention will be further described below with reference to examples. The evaluation items and measurement methods were as follows. (1) Peeling state ... The remaining coating layer was evaluated as peeling degree 3 by visually observing the degree of peeling of the substrate strip after the F step.
Was accepted. Peeling state = 3: All coating layers are peeled off Peeling state = 2: Non-peeling coating layer remains partially or in spots or a part of the multilayer coating layer remains on the entire surface Peeling state = 1: The state where the coating layer is not peeled off at all (2) Appearance of the molded product ... The presence or absence of foreign matter was visually confirmed. (3) Impact value ... Izod impact value with V notch was measured according to ASTM D256 on a test piece having a thickness of 1/8 inch. (4) Average molecular weight ... The viscosity average molecular weight (M) of the polycarbonate resin is H using methylene chloride as a solvent.
The intrinsic viscosity [η] is calculated by the gggins formula ηsp / c = [η] + k ′ [η] ² c, k ′ = 0.45, and the Schnell formula [η] = 1.23 × 10 ⁻⁴ M ^{0.83 is used.} I asked for M. (5) Water absorption rate: 50 ± 1 mm on one side, thickness 3 ± 0.
A 2 mm square plate is dried for 24 hours in a thermostat kept at 50 ° C. as a condition adjustment, and allowed to cool in a desiccator. The test piece was immersed in an immersion liquid (new distilled water) at 20 ° C. for 24 hours, and the weight change was measured to obtain the water absorption rate.

Example 1 2 at a viscosity average molecular weight of 15,100 and a water absorption of 0.20% by weight
Value phenol component is bisphenol A polycarbonate resin substrate (1.2 mm) / aluminum deposition layer (0.1μ
m) / UV coat layer (5 to 10 μm) / label printing layer (20 μm). Resin substrate A (diameter 12 c
m) was rolled by a two-roll machine manufactured by Otake Machinery Co., Ltd., which has a roll gap of 0.4 mm and a surface temperature of 130 ° C. (process A). The rolling condition at this time is roll speed =
High speed side 16 rpm, low speed side 14 rpm, roll diameter = 12
Inch and roll width = 24 inches. The length (major axis) of the rolled resin substrate was 13.8 cm, which was rolled to 1.15 times the length of the original substrate, and the coating layer on the entire surface had cracks. Next, as hot water treatment, it was immersed in heated water at 90 ° C. for 5 minutes and stirred while swelling. The ratio of the resin substrate at this time was 5% by weight with respect to the total of the resin substrate and the heated water, and the label printing layer and the protective coating layer were mainly peeled off (step B). Next, washing with water was performed to obtain a resin substrate from which the peeled coating layer was removed (step C). It was crushed by a crusher manufactured by Co., Ltd. (step D).

97% by weight of the obtained substrate strip did not pass through a circular hole having a diameter of 2 mm. This substrate strip is used to remove mainly the remaining aluminum vapor deposition components.
It was immersed in heated water at 0 ° C. for 30 minutes with stirring (step E). At this time, the proportion of the substrate strip was 15% by weight with respect to the total of the substrate strip and the heated water. Then, the aluminum vapor deposition component removed from the substrate strip was separated together with the heated water, and the transparent polycarbonate resin substrate strip was collected (step F). The obtained polycarbonate resin substrate strip was pelletized by a conventional method, dried at 120 ° C. for 5 hours, and then a test piece was molded at 270 ° C. by an injection molding machine manufactured by Japan Steel Works, Ltd. No foreign matter was observed in the molded product, and no unevenness was observed on the surface. Also, the impact value is 5 kgf · cm / cm
The viscosity average molecular weight of the test piece was 15,000, which was almost the same as the initial polycarbonate resin.

Examples 2 and 3 Using various resin plates shown in Table 1, the same procedure as in Example 1 was carried out except for the conditions shown in Table 1, and the results are shown in Table 1. The structures of the resin plates used in Tables 1 to 3 are as follows. Resin plate A: substrate / aluminum deposition layer / UV coating layer / label printing layer Resin plate B: substrate / aluminum deposition layer / UV coating layer Resin plate C: label printing layer / substrate / aluminum deposition layer / UV
Coating layer / label printing layer resin plate D: substrate / aluminum vapor deposition layer / UV coating layer / label printing layer resin plate E: substrate / aluminum vapor deposition layer / UV coating layer / acrylic adhesive layer / UV coating layer / aluminum vapor deposition layer / Substrate Here, the substrates of the resin plates A to C have a thickness of 1.2 mm, a water absorption rate of 0.20% by weight, a viscosity average molecular weight of 15,100, and an aromatic polycarbonate resin in which the divalent phenol component is phenol A (Teijin Chemical ( Manufactured by K.K.), the aluminum vapor deposition layer has a thickness of 0.1 μm, the UV coating layer (protective coating layer) has a thickness of 5 to 10 μm, and the label printing layer has a thickness of 20 μm.

The substrate of the resin plate D has a viscosity average molecular weight of 1
This is a substrate made of a copolymerized polycarbonate resin having a water absorption of 0.19% by weight at 5,000, and this copolymerized polycarbonate has a divalent phenol component of bisphenol A and 1,1-bis (4-hydroxyphenyl) -3,3. It is a 70:30 (mol%) copolymer of 5,5-trimethylcyclohexane. The resin plate E has a thickness of 0.6 mm and a water absorption rate of 0.2.
Made of aromatic polycarbonate (manufactured by Teijin Kasei Co., Ltd.) with 0% by weight, a viscosity average molecular weight of 15,100 and a bivalent phenol component of bisphenol A. The aluminum vapor deposition layer has a thickness of 0.1 μm and a UV coating layer (protection). The thickness of the coat layer) is 5
10 to 10 μm. These two sheets were pasted together with an acrylic UV-curing adhesive so that the aromatic polycarbonate surface was on the outside, so that the total thickness was 1.2 mm.

[0051]

[Table 1]

Examples 4 to 7 As a rolling machine for rolling, a two-roll machine (roll diameter = 12 inches) manufactured by Otake Machinery Co., which rotates at a constant speed, was used. The same procedure as in Example 1 was carried out except that the conditions shown in Table 2 were used, and the results are shown in Table 2.

[0053]

[Table 2]

Example 8 The same polycarbonate resin substrate (1.2 m) as in Example 1 having a viscosity average molecular weight of 15,100 and a water absorption of 0.20% by weight.
m) / aluminum vapor deposition layer (0.1 μm) / UV coating layer (5
Resin substrate A having a composition of (~ 10 μm) / label printing layer (20 μm) was continuously supplied to a washing machine and washed with warm water at 40 ° C. for 1.5 seconds to remove dust on the surface of the resin substrate. . The resin substrates continuously discharged were rolled by a two-roll machine manufactured by Otake Machinery Co., Ltd. with a roll gap of 0.2 mm and a surface temperature of 130 ° C. (step A). The rolling condition at this time is as follows: Roll speed = High speed side 16
rpm, low speed side 14 rpm, roll diameter = 12 inches, roll width = 24 inches. The length (major axis) of the rolled resin substrate was 15.8 cm, which was rolled to 1.32 times the length of the original substrate, and the coating layer on the entire surface had cracks.

The continuously discharged rolled resin substrates were successively conveyed by a conveyor and supplied to one end of the rotary drum. This rotating drum has a side wall of 17 mm
In addition, there are four areas formed by three dam plates in the drum, and when the resin substrate stays in a certain amount, it is moved to the next area by the rotation of the drum. . The number of rotations of the drum and the dam plate are adjusted so that the rolled resin substrate stays in the drum for 10 minutes so that the ratio of the resin substrate becomes 3% by weight with respect to the total of the resin substrate and the heated water. It was brought into contact with heated water at 80 ° C. (step B). The label printing layer and the protective coat layer, which are mainly peeled from the resin substrate, are separated from the pores together with the heated water (step C), and the resin substrate from which the peeled coating layer is substantially removed is the other end of the rotary drum. It was continuously discharged from the section.
These resin substrates were supplied to a crusher manufactured by Tomoki Co., Ltd., which has a rotary blade and a fixed blade that continuously rotate as they are, and a circular hole screen of 10 mm provided at the bottom, and crushed (step D). 98% by weight of the obtained substrate strip has a diameter of 2 m.
It did not pass through the circular hole of m.

The continuously discharged substrate strips were successively fed to one end of the rotary drum. This rotary drum has a structure in which a side wall has pores of 2 mm and a spiral partition plate is provided inside the drum. In the rotating drum, the ratio of substrate strips to the total of substrate strips and heated water is 8
The mixture was brought into contact with heated water at 90 ° C. for 25 minutes so as to have a weight percentage (step E). The aluminum vapor deposition component mainly removed from the substrate strip was separated from the pores together with the heated water, and the transparent substrate strip from which the coating layer was removed was continuously discharged from the other end of the rotary drum ( Step F). At this time, 2m
The small resin pieces having a size of less than m were also discharged from the pores together with the heated water to the outside of the rotary drum. These substrate strips were successively introduced into one end of a rotary drum type centrifugal dehydrator, and while blowing hot air of 125 ° C. into the rotary drum, the substrate strips were dehydrated and pre-dried for 2 minutes, The substrate strip discharged from the other end is conveyed to a hopper dryer,
It was dried at 120 ° C. for 5 hours. After that, Japan Steel Works, Ltd.
A test piece was molded at 270 ° C. by an injection molding machine.

Examples 9 and 10 Various resin plates shown in Table 3 were used, the same procedure as in Example 8 was carried out except for the conditions shown in Table 3, and the results are shown in Table 3.

[0058]

[Table 3]

Examples 11 to 14 As a rolling machine for rolling, a two-roll machine (roll diameter = 12 inches) manufactured by Otake Machinery Co., which rotates at a constant speed, was used. The same procedure as in Example 8 was carried out except for the conditions shown in Table 4, and the results are shown in Table 4.

[0060]

[Table 4]

Comparative Example 1 The resin substrate A was finely crushed as it was without performing a rolling step or a step of contacting with heated water, and pelletized in the same manner as in Example 1 to form a test piece. The results are shown in Table 5. Comparative Example 2 The resin substrate A was brought into contact with heated water at 120 ° C. for 660 minutes without performing the rolling process. Thereafter, the resin substrate was finely crushed and pelletized in the same manner as in Example 1 to form a test piece. The results are shown in Table 5. Comparative Example 3 The resin substrate A was not subjected to the rolling process, and the treatments after the process B were performed under the conditions of Table 5 in the same manner as in Example 1. The results are shown in Table 5.
It was shown to. Comparative Example 4 The resin substrate A was rolled under the conditions shown in Table 5 in the same manner as in Example 1. This rolled resin substrate was finely crushed without contact with heated water and pelletized in the same manner as in Example 1 to prepare a test piece. The results are shown in Table 5.

[0062]

[Table 5]

[0063]

According to the present invention, the resin component can be easily recovered and reused from the optical information recording medium which has been treated as industrial waste with almost no value in the past, and the optical recording medium can be reused. It contributes greatly to the recycling of resources from industrial development and global environmental protection, and is extremely effective industrially. Moreover, the process is simple, no pollution occurs, and it is industrially advantageous.

─────────────────────────────────────────────────── ─── Continuation of the front page (56) References JP-A-9-253481 (JP, A) International Publication 96/12598 (WO, A1) (58) Fields investigated (Int.Cl. ⁷ , DB name) B29B 17/00-17/02 B09B 3 / 00,5 / 00 C08J 11/00-11/28

Claims (27)

(57) [Claims] 1. When recovering the resin from an optical information recording medium in which at least one surface of a resin substrate is covered with a metal thin film layer, a printed coating film layer or a layer of a metal thin film and a printed coating film, The following step (1) a step of rolling the recording medium by passing it between at least one pair of rollers (step A), (2) a step of bringing the rolled recording medium into contact with heated water (step B), (3) A step of separating a substantial amount of the coating film peeled from the recording medium (step C), (4) a step of crushing the obtained recording medium (step D), (5) a heating of a small piece of the obtained recording medium. From the step of removing the metal thin film component by bringing it into contact with water (step E) and (6) separating the removed metal thin film component from the strip together with heated water and collecting and obtaining the strip (step F) A method for recovering a resin, which comprises: 2. The recovery method according to claim 1, wherein in step B, the rolled recording media are brought into contact with heated water while being entangled with each other. 3. The recovery method according to claim 1, wherein in step E, the strips of the recording medium are brought into contact with heated water while being entangled with each other. 4. The recovery method according to claim 1, wherein the steps B and C are carried out in one container. 5. The recovery method according to claim 1, wherein the steps B and C are carried out in a container equipped with a rotary drum having fine holes on the side walls. 6. The recovery method according to claim 1, wherein the steps E and F are carried out in one container. 7. The recovery method according to claim 1, wherein the steps E and F are carried out in a container equipped with a rotary drum having fine holes on the side walls. 8. The recovery method according to claim 1, wherein in step A, the recording medium is rolled to 1.08 to 2 times its original length. 9. The temperature of the pair of rollers in step A is
The recovery method according to claim 1, which is in the range of 30 to 140 ° C. 10. The temperature of the heated water in step B is 50
The recovery method according to claim 1, which is in the range of -100 ° C. 11. The recovery method according to claim 1, wherein the ratio of the recording medium and the heated water at the time of contact in the step B is such that the weight of the recording medium is in the range of 0.1 to 30% with respect to the total weight of both. 12. The recovery method according to claim 1, wherein in step C, a substantial amount of the release coating film is separated together with heated water. 13. The crushed strip in step D,
The recovery method according to claim 1, wherein the size is such that substantially 90% by weight or more of the circular hole having a diameter of 15 mm does not pass through the circular hole having a diameter of 15 mm. 14. The temperature of the heated water in step E is 50
The recovery method according to claim 1, which is in the range of -100 ° C. 15. The ratio of the strip of the recording medium and the heating water at the time of contact in the step E is such that the weight of the strip of the recording medium is 1 to 50% of the total weight of both. Recovery method. 16. A process, B process, C process, D process, E
The recovery method according to claim 1, wherein the step and the step F are continuously performed. 17. The recovery method according to claim 1, wherein the optical information recording medium is formed of a substrate made of a polycarbonate resin, a polymethylmethacrylate resin or an amorphous cyclic polyolefin resin. 18. The recovery method according to claim 1, wherein the optical information recording medium is formed of a substrate made of a polycarbonate resin. 19. The optical information recording medium is a compact disc having an aluminum metal thin film layer.
Recovery method described. 20. The recovery method according to claim 1, wherein the optical information recording medium is a DVD having an aluminum metal thin film layer. 21. When recovering the resin from an optical information recording medium in which a metal thin film layer, a printed coating layer or a layer of a metal thin film and a printed coating is coated on at least one surface of a resin substrate, At least the following step (1):
Supply between one pair of rollers and roll (process A),
(2) The rolled recording medium is supplied to one end of a rotary drum having pores, and the recording medium is brought into contact with heated water while being entangled with each other in the rotary drum (step B).
(3) A substantial amount of the coating film peeled off from the recording medium is separated from the pores of the rotating drum, and the recording medium is taken out from the other end of the rotating drum (step C). (4) The obtained recording medium Crushing (step D), (5) supplying the strips of the recording medium to one end of a rotary drum having pores, contacting the strips with heated water in the rotary drum (step E), (6) The metal thin film component removed from the pores of the rotary drum is separated together with heated water, and a strip is taken out from the other end of the rotary drum (F
Process), and a method for recovering resin. 22. The rotating drum in the step B has an internal structure in which the recording medium moves from one end to the other end by the rotation of the drum.
Recovery method described. 23. The rotating drum in the step E has an internal structure such that a strip of a recording medium is moved from one end to the other end by the rotation of the drum. Recovery method. 24. The recovery method according to claim 21, wherein in step A, the recording medium is rolled to 1.08 to 2 times the original length. 25. The temperature of the heated water in step B is 50
22. The recovery method according to claim 21, which is in the range of -100C. 26. In step D, the crushed strips are
22. The recovery method according to claim 21, which has a size that substantially passes through a circular hole having a diameter of 15 mm and 90% by weight or more thereof does not pass through a circular hole having a diameter of 2 mm. 27. The temperature of the heated water in step E is 50.
22. The recovery method according to claim 21, which is in the range of -100C.