JP2002031872A - Method for treating used heat developable material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To rapidly recover a base and silver from a heat developable material in high yields and to obtain an original starting material in a high yield by separating a coating on the PET base of a heat developable material and converting the PET to a supercritical fluid. SOLUTION: In the method for treating a used heat developable material containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder on the base, the base is separated from the heat developable material by a method comprising 1 a step for cutting the heat developable material into chips of 0.1 mm2 to 100 cm2 width (expressed in terms of area), 2 a step for immersing the chips in acidic or alkaline water containing an oxidizing agent at 60-140 deg.C to remove a coating from the base within 1 min to 8 hr, 3 a step for separating the base from the coating with a filter and 4 a step for drying the separated base with hot air at 40-100 deg.C.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technique for recovering a support, silver or a raw material of a support after using a heat-developable material for forming an image by thermal development. The present invention relates to a method for recovering a heat-developable material by making the support colorless and transparent, a method for recovering 90% or more of silver from the coating composition of the heat-developable material, and a method for recovering and recovering the recovered support to a raw material.

[0002]

2. Description of the Related Art In recent years, there has been a strong demand for photothermographic materials free of waste liquid from wet processing in view of environmental protection and workability in the fields of medical treatment and printing. There is a need for technology relating to photothermographic materials for photographic applications that can form black images. These photothermographic materials are usually developed at a temperature of 80 ° C. or higher, and are therefore called heat development materials.

Conventionally, this type of heat-developable material comprises a photosensitive layer containing high-sensitivity silver halide grains spectrally sensitized with a dye, an organic silver salt and a reducing agent, and a light irradiated on the photosensitive layer. An anti-irradiation layer (AI) that prevents light from passing through the interface and being irregularly reflected at the interface of the support, the intermediate layer, the adhesive layer, and the like.
Layer) or a backing layer (BC layer), and a protective layer is provided on the photosensitive layer and the BC layer to prevent scratches during handling.

Generally, a heat-developable material requires a step of uniformly heating after imagewise exposure to reduce the organic silver salt in the image area of the photosensitive layer. There is a method of irradiating the material, and a method of bringing the material into contact with a heated roller or a heated drum.

[0005] The heat-developed film is discarded after a certain storage period. Due to the recent increasing interest in the global environment, it is desired to reuse used materials as much as possible. As one of the concerns of the global environment, in order to suppress global warming, it is important to suppress the emission of carbon dioxide, which has a particularly large effect on global warming. An increase in the emission of carbon dioxide gas for re-use must be avoided.

The heat-developable material comprises 90 to 98% by weight of a polyethylene terephthalate (hereinafter referred to as PET) support, and 0.1 to 2% by weight of silver or a salt thereof on the support and 0.9 to 2% by weight.
-8% by mass of organic acids, dyes, dyes, etc. and binders.
In particular, since PET accounts for a large proportion of the heat-developable material, it is noted that PET is reused. An image forming material such as a heat developing material has a high purity of PET without impurities because a minute defect in an image is fatal.
It is necessary to play and use. The PET for image formation is used after being biaxially stretched so as to be optically isotropic, and has different polymerization catalysts and polymerization conditions from those used for PET bottles. Therefore, the contained trace components are different, and the management criteria for regeneration are also different.

A method of extracting PET components with high purity from the used image forming material using gelatin as a binder has been studied for a long time.
A method of separating T from a coating component and reusing PET has been proposed. Enzyme reactions have attracted attention as an environmentally friendly technology because the temperature is low and does not consume a large amount of heat energy. However, it has a drawback that the reaction is slow and it is difficult to control the activity of the enzyme.

[0008] Since it is desired that the heat developing material has as little moisture as possible, a polymer such as styrene-butadiene latex, cellulose derivative, or poval is used as a binder. Naturally, these polymers cannot be decomposed by the conventional enzymes that decompose gelatin, and a new decomposition method is required. Recently, research has been actively conducted to decompose a polymer into a raw material when the compound is present in a supercritical fluid, and to regenerate the polymer as a raw material. However, PET
Can be decomposed into a supercritical state, but terephthalic acid (hereinafter, referred to as TPA) as a raw material and ethylene glycol (hereinafter, referred to as TPA)
(Called EG) in high yields.

As a medium for forming a supercritical fluid, water, methanol, ethanol and carbon dioxide (carbon dioxide) have been attracting attention as preferred ones.

Water is the easiest substance to use, and the rate of hydrolysis of PET in supercritical water is 2 to 30 under pressure conditions.
It is known that the higher the temperature, the higher the temperature within the range of MPa and the temperature range of 280 to 600 ° C. JP-A-5-3
No. 1000 discloses a method of decomposing a resin by reacting a synthetic resin such as cellulose, lignin, silk, polyurethane, polystyrene, nylon, polyethylene, polypropylene and PET with supercritical or subcritical high-temperature and high-pressure water. However, there is no description about the yield of TPA or EG, which are raw material monomers obtained in supercritical water of PET. Japanese Patent Application Laid-Open No. 2000-103901 discloses a method of decomposing by using an acid as a catalyst. When decomposed with an acid, solid TPA is generated.
It is difficult to distinguish from ET, and the end point of the reaction is difficult to understand. The shorter the reaction time, the greater this risk.

On the other hand, a method of decomposing in a supercritical state with methanol or ethanol is known. A conventional method of decomposing with methanol or ethanol is a method of recovering TPA as dimethyl or diethyl ester. Is a method of using PET or a material similar to PET, but a recent PET synthesis method is a direct polymerization method using terephthalic acid itself instead of terephthalic acid ester, and dimethyl terephthalate or diethyl terephthalate is used. Further, a step of converting terephthalic acid is required.

[0012] The method using carbon dioxide is as follows:
Since it can be brought into a supercritical state under the condition of 3 MPa, it has the advantage that it can be brought into the supercritical state at a high pressure but at a low temperature, and has the advantage that it can be separated as a gas when brought to normal pressure after the reaction. The recovery method was difficult to handle because carbonate ions were esterified with EG and solids of TPA and PET as a raw material could not be distinguished.

As described above, a reaction system for depolymerizing PET in a supercritical high-temperature and high-pressure fluid has been conventionally known. However, both of TPA and EG as raw material monomers obtained can be obtained in high yield. Recovery methods have not yet been established.

[0014]

A first object of the present invention is to provide a support for a heat-developable material and an undeveloped or developed composition coated on the support for reusing the heat-developable material. And a method for efficiently separating the same. A second object relates to a method for further recovering silver from a coating composition separated from used thermal developing material. A third object relates to a method for decomposing a support separated from a used heat developing material into raw materials so that the support can be reused.

[0015]

The above object of the present invention is attained by the following constitutions.

The method of separating the support from the heat-developable material containing the photosensitive silver halide grains, the organic silver salt, the reducing agent and the binder on the support is carried out by converting the heat-developable material to an area having a width equivalent to the area of the heat-developable material. Cutting into small pieces of ¹ mm ² to 100 cm ² ,
The small pieces are acidified or alkaline 60-1 containing an oxidizing agent.
Removing the coating film from the support in water at 40 ° C. within 1 minute to 8 hours, separating the support and the coating film with a filter,
Drying the separated support with hot air at 40 to 100 ° C.

Incidentally, 0.1 to 30% by mass of an organic coagulant having a sulfonic acid group or a carboxylic acid group is added to the coating film component containing silver separated from the support and dispersed in water to precipitate and precipitate. Solidify, recover the silver by incineration of the solidified composition, the coagulant is styrene sulfonic acid, acrylic acid,
Any of those selected from polymers having naphthalenesulfonic acid is preferred.

Further, the dried support is subjected to a critical state of methanol, ethanol, carbon dioxide or water for 10 seconds to 180 minutes in the presence of an alkaline catalyst of 1 ppm to 60,000 ppm based on the mass of the supercritical fluid. Decompose, then 1 ppm ~
The above-mentioned object of the present invention is also attained by a method for treating a spent thermal developing material which is decomposed in the presence of 60,000 ppm of an acid catalyst for 10 seconds to 180 minutes and then brought to 80 ° C. or less within 15 minutes.

Hereinafter, the present invention will be described in detail. The heat-developable material of the present invention usually comprises at least one photosensitive layer and at least two layers comprising a layer adjacent to the photosensitive layer on a support, and a BC provided on the opposite side of the photosensitive layer.
And its protective layer. The photosensitive layer contains photosensitive silver halide grains that may be sensitized with a spectral sensitizing dye, and the photosensitive layer or a layer adjacent thereto contains an organic silver salt or a silver salt as a silver source. A reducing agent for developing to form a silver image is contained. The photosensitive layer or a layer adjacent to the photosensitive layer contains a polymer binder, a hydrophilic binder, or a hydrophobic binder that provides a thermal development field. A containing an anti-irradiation or anti-halation dye as another layer
An I layer or a BC layer is provided. The photosensitive layer may contain a color tone agent for adjusting the color tone of the silver image, if necessary.

The organic silver salt, reducing agent, silver halide, binder and main additives used in the present invention will be described below.

(Organic Silver Salt) The organic silver salt contained in the heat-developable material is a reducible silver source, and organic acids, heteroorganic acids and silver salts of acid polymers containing a reducible silver ion source can be used. Used. Also useful are organic or inorganic silver salt complexes wherein the ligand has a total stability constant for silver ions of 4.0 to 10.0. Examples of silver salts are described in Research Disclosure (RD) 17029 and 29996, and salts of organic acids, such as gallic acid, oxalic acid, behenic acid,
Salts such as stearic acid, palmitic acid, lauric acid and arachidic acid are included.

(Reducing Agent) Examples of preferred reducing agents contained in the heat-developable material include the above-mentioned RD 17029, such as US Pat. Nos. 3,770,448, 3,773,512 and 3,593,863. And 299963, and bisphenols (bis (2-hydroxy-3-t-butyl-5-methylphenyl) methane, 2,2-bis (4-
(Hydroxy-3-methylphenyl) propane, 4,4-
Ethylidene-bis (2-t-butyl-6-methylphenol) and the like, and particularly preferred reducing agents are the compounds shown below.

[0023]

Embedded image

The amount of the reducing agent to be used is preferably 1 × 10 ⁻² to 10 mol, more preferably 1 × 1 to 10 mol, per mol of silver.
0 ^{-2 to} 1.5 mol, and in the coating solution, a powder or tablet-like solid substance is added, and dissolved in an organic solvent of alcohol such as methanol or ethanol, or a ketone such as methyl ethyl ketone, acetone or methyl isobutyl ketone. All solutions can be added.

(Silver halide grains) The photosensitive silver halide contained in the photosensitive layer of the heat-developable material can be obtained by any method known in the field of photographic technology such as a single jet or double jet method, for example, by an ammonia method. , A neutral method, an acidic method, etc., and then mixed with other components of the present invention and introduced into the composition used in the present invention. In this case, in order to sufficiently contact the photosensitive silver halide with the organic silver salt, for example, as a protective polymer when preparing the photosensitive silver halide, US Pat.
706,564, 3,706,565, 3,7
No. 13,833, 3,748,143, British Patent No. 1,362,970, etc., means using polymers other than gelatin such as polyvinyl acetals, and British Patent No. 1,354,186. Means for enzymatically degrading the gelatin of the photosensitive silver halide emulsion as described, or preparing the photosensitive silver halide grains in the presence of a surfactant, as described in US Pat. No. 4,076,539. Accordingly, each means such as a means for omitting the use of the protective polymer can be applied.

The photosensitive silver halide preferably has a small grain size in order to suppress white turbidity after image formation and to obtain good image quality. The average particle size is 0.
Those having a thickness of 1 μm or less, preferably 0.01 to 0.1 μm, particularly 0.02 to 0.08 μm are preferred. The shape of the silver halide is not particularly limited, and may be cubic, octahedral, so-called normal crystals, or non-normal crystals, such as spherical, rod-shaped, or tabular grains. There is no particular limitation on the silver halide composition,
Any of silver chloride, silver chlorobromide, silver chloroiodobromide, silver bromide, silver iodobromide and silver iodide may be used.

The amount of the silver halide is 50% by mass or less, preferably 25 to 0.1% by mass, more preferably 15 to 0.1% by mass based on the total amount of the silver halide and the organic silver salt described below.
% By mass.

(Spectral Sensitizing Dye) The spectral sensitizing dye used in the present invention may be optionally used, for example, as described in JP-A-63-159814.
No., 60-140335, 63-231437
No., 63-259,651 and 63-304242
And U.S. Pat. No. 4,639,4.
No. 14, 4,740,455, 4,741,96
No. 6, No. 4, 751, 175, No. 4, 835, 096
Sensitizing dyes described in Nos. 1 and 2 can be used. Useful sensitizing dyes for use in the present invention include, for example, RD17643, IV-
Section A (December 1978, p. 23), Section 831X (1
August 978, p. 437). In particular, a sensitizing dye having a spectral sensitivity suitable for the spectral characteristics of various scanner light sources can be advantageously selected. For example, JP-A-9-34078, 9
Compounds described in JP-A-54409 and JP-A-9-80679 are preferably used.

(Binder) As the polymer binder used in the photosensitive layer or the non-photosensitive layer of the heat developing material, silver halide,
A preferable material is selected as a place where the organic silver salt and the reducing agent react. Examples of the polymer binder include, for example, alcohols such as methanol and ethanol, ketones such as methyl ethyl ketone and acetone, polymers used by dissolving in polar solvents including dimethyl sulfoxide and dimethylformamide, and water-dispersed polymers. is there. Further, the glass transition point of the preferred polymer composition is from -20 to 12
0 ° C is preferable, and particularly preferably -5 to 100 ° C. If the glass transition point is high, the temperature for thermal development is high, and if the glass transition point is low, fogging is likely to occur, resulting in a decrease in sensitivity and softness.

Examples of the polymer used by dissolving in the above-mentioned polar solvent or the like include cellulose derivatives such as hydroxyethylcellulose, carboxymethylcellulose, methylcellulose, ethylcellulose and acetylbutylcellulose; polyvinyl alcohol, modified polyvinyl alcohol, polyvinyl butyral, and sodium polyacrylate. , Polyethylene oxide, acrylamide-acrylate copolymer, styrene-maleic anhydride copolymer, polyacrylamide, polystyrene, polyvinyl acetate, polyurethane, polyacrylic acid, polyacrylate, styrene-butadiene copolymer Acrylonitrile-butadiene copolymer, vinyl chloride-vinyl acetate copolymer, styrene-butadiene-acryl copolymer, and the like. Particularly after drying and after forming a film, those having a low equilibrium water content of the coating film are preferable, and particularly those having a low water content include, for example, cellulose acetate, cellulose acetate butyrate, poly (methyl methacrylic acid) and the like. Acrylates), poly (acrylic acid), poly (methacrylic acid), poly (vinyl chloride), copoly (styrene-maleic anhydride), copoly (styrene-acrylonitrile), copoly (styrene-butadiene), poly (vinyl) Acetal) s (eg, poly (vinyl formal) and poly (vinyl butyral)), poly (esters), poly (urethanes), phenoxy resins, poly (vinylidene chloride), poly (epoxides),
Poly (carbonate) s, poly (vinyl acetate),
Cellulose esters can be mentioned.

The water-dispersed polymer is preferably a fine particle having an average particle diameter in the range of 1 nm to several μm and dispersed in an aqueous dispersion medium. Among the water-dispersed polymers widely used as binders for water-based coatings, latex is particularly preferred from the viewpoint that water resistance can be improved. The amount of the latex used for obtaining water resistance as a binder is determined in consideration of coatability, but is preferably as large as possible from the viewpoint of moisture resistance, and is preferably 50 to 100% by mass, and 80 to 100% by mass based on the total binder. Is preferred.

(Dye) The heat-developable material is provided with an AI layer or a BC layer for preventing irradiation or halation of the heat-developable material, if necessary. The dye used for these layers is an image exposure light. Any dye can be used as long as it absorbs, but preferably the above-mentioned US Pat. No. 5,384,237.
And the like. If the dye used is not heat-decolorable, the amount used is limited to a range that does not cause image damage to the heat-developable material. If the heat-decolorable dye is used, a necessary and sufficient amount of the dye is added. be able to.

(Color Toning Agent) It is preferable to add a color toning agent to the photothermographic material. An example of a suitable toning agent is RD170
No. 29, which includes the following.

Phthalazinone, phthalazinone derivatives or metal salts of these derivatives (4- (1-naphthyl) phthalazinone, 6-chlorophthalazinone, 5,7-dimethyloxyphthalazinone, and 2,3-dihydro-1,4 -Polyhalomethane compound dione); a combination of phthalazinone and a sulfinic acid derivative (6-chlorophthalazinone + sodium benzenesulfinate or 8-methylphthalazinone +
a combination of a polyhalomethane compound and phthalic acid; a polyhalomethane compound (including an adduct of the polyhalomethane compound) and maleic anhydride;
And phthalic acid, 2,3-naphthalenedicarboxylic acid or o
-Combination with phenylene acid derivatives and their anhydrides (e.g. phthalic acid, 4-methylphthalic acid, 4-nitrophthalic acid and tetrachlorophthalic anhydride), phthalazine, at least one compound selected from phthalazine derivatives.

(Print-out Preventing Agent) As a print-out preventing agent, a polyhalomethane compound is preferable, and a compound having a tribromomethyl group is particularly preferable. The compound is directly or indirectly attached to an aryl-based or non-aryl-based core having the substituent. Compounds which are bound to each other can be mentioned. As the divalent bonding group in the case of indirect bonding, a sulfonyl group or a carbonyl group is preferable. Preferred specific compounds include tribromomethylbenzene, tribromomethylpyridine, tribromomethylquinoline, tribromomethyltriazole, tribromomethylsulfonylquinoline, and tribromomethylsulfonylpyridine.

(Matting agent) The matting agent may be either an organic or inorganic substance. Examples of the inorganic matting agent include silica described in Swiss Patent 330,158 and French Patent 1,296,995. Glass powder, alkaline earth metal salts described in British Patent 1,173,181 and the like can be used. Examples of organic matting agents include starch described in U.S. Pat. No. 2,322,037, starch derivatives described in Belgian Patent 625,451 and British Patent 981,198, and JP-B-44-3643. Polyvinyl alcohol, polystyrene or polymethacrylate described in Swiss Patent No. 330,158, polyacrylonitrile described in US Pat. No. 3,079,257, polycarbonate described in US Pat. No. 3,022,169, and the like can be used. .

The shape of the matting agent may be either regular or irregular, but is preferably regular and spherical. The size of the matting agent is represented by a diameter when the volume of the matting agent is converted into a sphere. In the present invention, the particle diameter of the matting agent indicates the diameter converted into a sphere.
The matting agent used in the present invention has an average particle size of 0.5 to 1
0 μm, more preferably 1.0 to
It is 8.0 μm. The matting agent has a monodispersity of 50 or less, more preferably 40 or less, and particularly preferably 20 or less. here,
The monodispersity of the particles is represented by a number obtained by dividing the standard deviation of the particle size by the average value of the particle size and multiplying by 100. The method of adding the matting agent may be a method in which the matting agent is dispersed in a coating solution in advance, or a method in which the matting agent is sprayed before the drying is completed after the coating solution is applied. When a plurality of types of matting agents are added, both methods may be used in combination.

(Support) As a support for the heat-developable material,
A support such as paper, synthetic paper, nonwoven fabric, metal foil, plastic film, etc. can be used, but in the present invention, PET whose dimensional change is small due to heat is suitable.

<Image Exposure> The image exposure for forming an image on the heat-developable material is performed, for example, at an emission wavelength of 660 nm or 670 nm.
It is preferably performed by laser scanning exposure such as nm, 780 nm, 810 nm, and 830 nm. At the time of exposure, the temperature is in the range of 5 to 30 ° C, and the relative humidity (RH) is 30 to 60.
% Is preferred.

<Developing process> The developing temperature of the heat developing material is 12
The temperature is preferably 0 ° C. ± 10 ° C. for 1 to 60 seconds. The heat of the heat developing material is preferably supplied from a heat roller or a heat drum, and may be other microwaves or ultrasonic waves.

<Treatment of Used Thermal Developing Material> Used thermal developing material is first cut into small pieces by a shredder (shredder). Use a cross-type shredder that cuts vertically and horizontally.
It is preferred to crush into squares of 1 mm ^{2 to} 100 cm ² . If the size of the small pieces is smaller than this, handling becomes difficult, such as a decrease in the crushing speed and scattering of dust. On the other hand, if it is larger than this, it is not easy to peel off the coating film from the support.

At the time of crushing, a method of installing an ion wind type static eliminator to prevent electrification, and at the time of crushing, RH 50%
A humidity controller for maintaining the above conditions is installed so that the humidity does not become low, while the humidity does not become 80% or more. If the relative humidity is too high, the small pieces adhere to each other and it becomes difficult to peel off the coating composition from the support.

Small pieces of the crushed film are introduced into an acidic or alkaline aqueous solution containing an oxidizing agent. The oxidizing agent is used for decolorizing dyes and dyes and decomposing organic compounds, and specific examples thereof include hydrogen peroxide, ozone and oxygen.

Hydrogen peroxide can be used by appropriately diluting a commercially available 38% concentration, but the preferred concentration is preferably in the range of 0.01 to 20% by mass in an aqueous alkaline solution. If the concentration is further diluted, a sufficient oxidizing effect cannot be obtained, and if the concentration is further increased, it is dangerous.

Ozone can be obtained by a photo-oxidation method in which air is irradiated with ultraviolet rays. The preferred ozone concentration is 1 to 10,000 in alkaline or acidic water.
The amount is equivalent to 0 ppm.

When oxygen is used as the oxidizing agent, there are a case where air is used and a case where pure oxygen is used. If pure oxygen is used, 99% oxygen, 99.
Ultrapure oxygen of 9% oxygen, 99.99% oxygen or higher may be used. It can be used by returning liquefied oxygen enclosed in a commercially available oxygen cylinder to gas. As another method, there is a method of increasing the oxygen concentration of air using an oxygen-enriched film and using a high oxygen concentration. Since high energy is required to obtain oxygen, it is preferable to use an oxygen-enriched film or the like to increase the oxygen concentration in the air to 20 to 40%. Oxygen concentration is 1 to 1 in water
It is preferable to supply so as to contain up to 0.00000 ppm.

As the coated portion is peeled off from the support,
Although the composition of the applied portion floats or precipitates in water, it is preferable to use a flocculant as a method of causing all of the composition to flocculate and settle at a high speed. As the coagulant, a polymer having an organic carboxylic acid or an organic sulfonic acid is preferable,
Polymers obtained by radical copolymerization of polystyrene sulfonic acid or styrene sulfonic acid with other vinyl monomers such as maleic acid, methyl acrylate and ethyl acrylate, and polyacrylic acid or acrylic acid with other vinyl monomers such as acrylic acid Examples include polymers obtained by radical copolymerization with a monomer such as methyl, ethyl acrylate or methyl methacrylate, and polynaphthalene sulfonic acid obtained by crosslinking naphthalene sulfonic acid with an aldehyde compound. These polymers have a molecular weight of 4000 to 1,000,000, and this range is preferable even when measured by a number average molecular weight or a mass average molecular weight. The ratio between the number average molecular weight and the mass average molecular weight indicates a molecular weight distribution, and when the ratio is close to 1, the molecular weight distribution is narrow, and preferably 1.0 to 2.0. Although a smaller value is preferable, a value smaller than 1.2 is not preferable from an economical viewpoint because the synthesis yield is reduced. On the other hand, if the distribution is as broad as 2.0 or more, it is difficult to aggregate and the efficiency is lowered, which is not preferable.

<Supercritical fluid> When water is used as the supercritical fluid, the temperature is 200 to 800 ° C and the pressure is 6 to 100.
MPa is preferable. When carbon dioxide gas is used, the condition for forming a supercritical fluid is 31 ° C. and the pressure is 7.29 MPa, but the preferable use range is 100 to 300 ° C. and the pressure is 10 MPa.
When ethanol is used, the conditions for the supercritical state are a temperature of 240.9 ° C. and a pressure of 6.14.
MPa, but the preferred use range is 250 to 800 ° C.
When the pressure is 7 to 80 MPa and methanol is used, the conditions may be the same as those for ethanol. The reaction time in any supercritical fluid is preferably from 1 second to 180 minutes.

The reaction temperature in the supercritical fluid may be any pressure as long as it is higher than the temperature at which the supercritical fluid is formed. However, if the range in which the reaction conditions are set is narrow, it is difficult to control the reaction conditions. It is important to select a wide range of appropriate control conditions. Considering the economics of production facilities and operating energy for setting the temperature and pressure to excessive levels to achieve the critical state, it is preferable to set the temperature and pressure as low as possible. In terms of facilities, the temperature is 300 ° C or less and the pressure is 50
MPa or less is practical.

P of the high-temperature and high-pressure fluid supplied to the supercritical reactor
The mass ratio to ET (hereinafter abbreviated as fluid ratio) is 2 to
It is in the range of 10, preferably 2-7. The amount of fluid required for the decomposition of PET must be sufficient to dissolve the raw material monomer to be produced. In the case of PET, if the fluid ratio is less than 2, the produced EG and TPA must be completely dissolved. Can not be done. On the other hand, if the fluid ratio exceeds 10,
While the decomposition reaction has the advantage of being generated promptly, it is not preferable because the size of the reactor, equipment for high-temperature and high-pressure production, fluid treatment, etc. increases, and the energy required for the treatment increases.

The reactor used may be a batch type or a continuous type. As the shape of the reactor, for example, a pipe type, a spherical type, a cylindrical vertical type or a horizontal type can be used. PE
Means for realizing the dispersion of T in a high temperature and high pressure fluid in a molten state is not particularly limited, but, for example, a static dispersion means using a filler such as a partition, a static mixer, and / or a stirrer, a mixer Forcibly dispersing means using an insert performing reciprocating operation or rotating operation can be used alone or in combination of two or more. It is also preferable to supply the pulverized PET to the reactor as a slurry in a fluid. Further, using forced dispersing means at multiple points in the reactor to complete the reaction quickly, and / or
Alternatively, it is preferable to keep the flow in the reactor in a turbulent range.

In the reaction of depolymerizing PET using the reactor, the average size of the small pieces of PET dispersed in the high-temperature and high-pressure fluid (hereinafter, abbreviated as average size) is 10%.
It is preferably 0 cm ² or less. Average size 100c
If it exceeds m ² , the recovery rate of EG among the raw material monomers decreases, which is not preferable. The smaller the average area is, the larger the contact area with the high-temperature and high-pressure fluid per unit PET mass is, which is preferable because the decomposition reaction speed is increased. However, it takes much labor to disperse the particles to less than 0.1 mm ^2. In addition, since it hardly affects the recovery rate of the EG component, 0.1 mm ² or more is preferable.

A method for calculating the average area will be described. The average width is obtained by extracting a sample from a population of small pieces, and since the thickness direction is constant, the area of the small piece is calculated from the width and length directions of the small piece, and the average value is calculated. The optimum value of the first reaction time in the presence of the alkali catalyst and the second reaction time in the presence of the acid treatment catalyst in the reactor is determined optimally by the reaction temperature and pressure. Due to the above difficulty, the reaction is performed in 10 seconds or more, and from the viewpoint of the yield of the raw material monomer and the productivity, the reaction is preferably performed in 60 minutes or less, 15 seconds or more, more preferably 30 minutes or less, 20 seconds or more. If the time exceeds 180 minutes, decomposition proceeds and the yield decreases.

The cooling time after the completion of the second reaction is preferably as short as possible. If the cooling time is long, a reaction which could be decomposed into a raw material in a supercritical state may occur in a non-supercritical state. It is preferable to cool to room temperature to 80 ° C., more preferably within 5 minutes.

The raw material monomer produced by the method of the present invention passes through a solid-liquid separation section for separating and removing solids or insolubles from the fluid solution after the reaction, if necessary, and then is subjected to ordinary crystallization, distillation, etc. By performing the separation and purification operation, a monomer having higher purity can be recovered.

[0056]

The present invention will be described below with reference to examples, but embodiments of the present invention are not limited to these examples. Unless otherwise specified, “%” in the examples represents “% by mass”.

Example 1 [Preparation of Thermal Developing Material] <Preparation of Subbed Support> A corona discharge treatment of 8 W / m ² · min. An undercoat coating solution a-1 is applied so as to have a dry film thickness of 0.8 μm and dried to form an undercoat layer A-1,
On the opposite side, the following undercoating coating solution b-1 was dried to a thickness of 0.8 μm.
m and dried to provide an undercoat layer B-1.

Undercoating coating liquid a-1 270 g of a copolymer latex liquid (solid content 30%) of butyl acrylate / t-butyl acrylate / styrene / 2-hydroxyethyl acrylate (30/20/25/25%) Coating solution b-1 Copolymer latex liquid of butyl acrylate / styrene / glycidyl acrylate (40/20/40%) (solid content: 30%) 270 g Subsequently, the surface of undercoat layer A-1 and undercoat layer B-1 8W
/ M ² · m of corona discharge, and the following lower coating liquid a-2 on the lower coating layer A-1 and the lower coating liquid b below on the lower coating layer B-1. -2 was applied and dried so as to have the following coating weight, to thereby provide undercoating upper layers A-2 and B-2 having an antistatic function.

Undercoating upper layer coating solution a-2 Styrene / butadiene copolymer 0.4 g / m ² silica particles (average particle size 3 μm) 0.1 g / m ² Undercoating upper layer coating solution b-2 Styrene / butadiene copolymer Combined 0.4 g / m ² silica particles (average particle size 3 μm) 0.1 g / m ² <Preparation of silver halide particle emulsion A> 7.5 g of inert gelatin and 10 mg of potassium bromide were dissolved in 900 ml of water, and the temperature was adjusted. After adjusting the pH to 35 ° C. and 3.0, 370 ml of an aqueous solution containing 74 g of silver nitrate and 370 ml of an aqueous solution containing potassium bromide and potassium iodide in a molar ratio of (98/2) are used.
Was added by a controlled double jet method over 10 minutes while keeping pAg at 7.7. Thereafter, 0.3 g of 4-hydroxy-6-methyl-1,3,3a, 7-tetrazaindene was added, the pH was adjusted to 5 with sodium hydroxide, the average particle size was 0.06 μm, and the projected diameter area was And a [100] face ratio of 87%, thereby obtaining cubic silver iodobromide grains. This emulsion was subjected to coagulation sedimentation using a gelatin coagulant and desalting treatment, and 0.1 g of phenoxyethanol was added to adjust the pH to 5.9 and the pAg to 7.5 to obtain silver halide grain emulsion A.

<Preparation of Organic Silver Salt> In 4720 ml of pure water, 111.4 g of behenic acid, 83.8 g of arachidic acid,
54.9 g of stearic acid were dissolved at 80 ° C. Next, while stirring at high speed, 540.2 ml of a 1.5 mol / L aqueous sodium hydroxide solution was added, 6.9 ml of concentrated nitric acid was added, and the mixture was cooled to 55 ° C. to obtain a sodium organic acid solution. While maintaining the temperature of the organic acid sodium salt solution at 55 ° C., 22 g of the silver halide grain emulsion A (silver 0.03 g) was used.
8 mol) and 450 ml of pure water, and the mixture was stirred for 5 minutes. Next, 760.6 ml of a 1 mol / L silver nitrate solution was added over 2 minutes, the mixture was further stirred for 20 minutes, and water-soluble salts were removed by filtration. Thereafter, the conductivity of the filtrate was 2 μS /
Washing with deionized water and filtration were repeated until the volume reached 1 cm, and finally methyl ethyl ketone (MEK) was added to make the volume to 1 liter.

<Coating of photosensitive layer and BC layer> The following layers were sequentially formed on the undercoated support to prepare a sample. The drying was performed at 45 ° C. for 1 minute.

<< Coating on BC Layer Side >> On the back surface side, the following coating solution was applied and dried in the following amount to form a BC layer.

Coating solution for BC layer Cellulose acetate butyrate 1.8 g / m ² Dye C 1.2 × 10 ⁻⁵ mol / m ² Activator (N-propylperfluorooctylsulfonamidoacetic acid) 0.02 g / m ² << Coating of BC protective layer >> The following coating solution is applied on the BC layer.
Dried.

Coating solution for BC protective layer Cellulose acetate butyrate 1.1 g / m ² Activator (N-propyl perfluorooctylsulfonamidoacetic acid) 0.02 g / m ² Matting agent (PMMA: average particle diameter 5 μm) 0.12 g / M ² << Coating on photosensitive layer >><< Application of AI layer >> A coating solution having the following composition was coated on a support opposite to the BC layer and dried.

AI layer coating solution Binder (PVB-1) 0.4 g / m ² Dye C 1.2 × 10 ⁻⁵ mol / m ² << Coating of photosensitive layer >> Coating of the following composition for forming a photosensitive layer A liquid was prepared. This coating solution was kept at about 35 ° C., and was applied and dried so as to have the following coating weight. 1.4g as silver
/ M ² of the organic silver salt preparation was mixed with the polymer binder.

Coating solution for photosensitive layer Binder (PVB-1) 2.6 g / m ² Spectral sensitizing dye A 2 × 10 ⁻⁵ mol / m ² Antifoggant-1 (pyridinium hydrobromide perbromide) 0.3 mg / m ² Antifoggant-2 (isothiazolone) 1.2 mg / m ² Printout inhibitor (tribromomethylsulfonylquinoline) 0.126 g / m ² Reducing agent 4 3.3 mmol / m ² << Coating of surface protective layer >> A coating solution prepared by adding the following composition was coated on the photosensitive layer so as to have the following coverage.
After drying, a surface protective layer was formed.

Coating solution for surface protective layer Cellulose acetate butyrate 1.2 g / m ² Toning agent (phthalazine) 0.26 g / m ² 4-methylphthalic acid 0.7 g / m ² Tetrachlorophthalic acid 0.2 g / m ² Tetra Chlorophthalic anhydride 0.5 g / m ² Silica matting agent (average particle size 5 μm) 0.5 g / m ² The structure of the additive used in each coating solution is as follows.

PMMA: polymethyl methacrylate

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Embedded image

[Treatment of Thermal Developing Material] The thermal developing material prepared as described above was exposed to an infrared laser having a wavelength of 810 nm so as to have a concentration of 1.5, and was heated at 120 ° C./8 by a thermal developing machine.
A sample (processed sample) heat-developed for 2 seconds to prepare 3 m ² . The obtained sample was cut into small pieces having the size (average size) shown in Table 1 and charged into a 60-liter stainless steel pot. Then, an aqueous solution containing an oxidizing agent and an alkaline agent or an aqueous solution containing an oxidizing agent and an acid was added. One liter was added thereto, and the mixture was allowed to react at a constant temperature and for a certain period of time with stirring, thereby peeling off the coating material on the support from the support. The oxidizing agent used had a purity of 99% or more. The coating material on the support that had been peeled off was separated after a certain time by a 200 μm filter, and the support was dried. The color tone of the separated support and the degree of peeling of the coated article from the support were evaluated in five steps according to the following.

Table 1 shows the results. << Degree of Peeling >> 1: Level peeled at 99.5% or more 2: Level peeled at 99.0% to less than 99.5% 3: Level peeled at 98.0% to less than 99.0% 4:96 0.0% to less than 98.0% Peeled level 5: Less than 96.0% peeled level << Color >> 1: Transparent level without adhesion of pigment or dye 2: Slight adhesion of pigment or dye Level that is almost transparent but not practical 3: Level that is not problematic for practical use 4: Undesirable level where pigments and dyes are observed, and 5: Worst level with pigments and dyes adhered

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[Table 1]

From Table 1, according to the present invention, it is possible to separate the coating material on the support of the heat developing material with a high degree of peeling.
Moreover, it can be seen that the support having excellent color tone is recovered.

Example 2 In this example, an organic coagulant was added to a state in which the coating film component in Example 1 was suspended in an aqueous solution to precipitate and solidify, and the aggregate was incinerated to recover silver. That is, the experiment N of Example 1
o. In a solution decomposed in an alkali aqueous solution or an acid solution of 109 and 112, polystyrene sulfonic acid (P1) having a molecular weight of 700,000 and polyacrylic acid having a molecular weight of 600,000 (P1) are used as a flocculant having a sulfonic acid group or a carboxylic acid group. P2),
It was condensed with naphthalenesulfonic acid (P3) having a molecular weight of 500,000, incinerated at 900 ° C., and gas generated during incineration was passed through an aqueous solution to recover solidified silver.

Table 2 shows the flocculant, the amount of the flocculant added, the change in the flocculation time, and the recovery rate of silver when the solidified product was incinerated.

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[Table 2]

It can be seen that the use of the flocculant of the present invention allows silver to be recovered in high yield. Example 3 Here, the experiment No. 1 of Example 1 was used. The heat-developable material 109 from which the coating was peeled off was used to decompose in a supercritical fluid. Supercritical fluid is 8cm thick, 15cm inner diameter SUS
Experiment No. 316 was placed in a spherical reaction tube made of 316. 150 g of PET obtained by the method of Example 109, 640 g of ion-exchanged water, SUS
316 made balls 4 mm and 8 mm in diameter
First, an alkali catalyst was charged (25 ° C., 0.1
1 ppm to 60,000 p based on the mass of the working fluid at 1 MPa pressure
pm), the inside of the reaction tube was replaced with nitrogen having a purity of 99.9%, and the reaction was carried out under a certain condition (temperature ° C, pressure MPa). The mass of the fluid is charged in the range of 1 ppm to 60,000 ppm), the inside of the reaction tube is replaced with nitrogen again, and a certain condition (temperature, ° C.,
The reaction was carried out at a pressure of MPa). The reaction tube was allowed to react with the internal ball mill stirring while rotating at a rotation speed of 1 rotation / minute while the rotation axis was fixed in the horizontal direction (each condition is shown in Table 3).

In the case of methanol and ethanol used for the supercritical fluid, 610 g of each was charged instead of ion-exchanged water, and the same procedure was carried out as for water.
It was shown to. The carbon dioxide gas is shown in Table 6. After the completion of the reaction, the mixture was cooled to 60 ° C. or less for the time (minute) described in each table.
The contents in the reaction tube were analyzed, and the results are shown in Tables 3 to 6.

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[Table 3]

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[Table 4]

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[Table 5]

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[Table 6]

The PET is decomposed in a supercritical state in the presence of the alkali catalyst of the present invention, and then is re-decomposed in the presence of an acid catalyst.
It can be seen that by decomposing T in a supercritical state, the raw material monomer can be recovered in a high yield.

[0084]

According to the method of the present invention, both terephthalic acid and ethylene glycol, which can be used as a raw material for polymerizing a polymer, can be recovered from PET at high speed and in a high yield. It turns out that it is effective as a method.

Continued on the front page (51) Int.Cl. ⁷ Identification symbol FI Theme coat II (reference) B29B 17/00 G03C 5/00 A 4D062 C02F 1/56 11/24 4F301 G03C 5/00 B09B 3/00 304H 11/24 5/00 ZABZ F term (reference) 2H016 CA00 CA01 2H123 AB00 AB03 AB23 AB28 CB00 CB03 CC00 4D004 AA07 AA50 BA05 CA04 CA10 CA35 CA36 CA39 CA42 CB36 DA02 DA03 DA06 DA20 4D015 BA05 BA06 BB05 CA20 DB12 DB18 DB30 EA03 FA04 AB20 AC06 AC21 AC22 BA16 CA33 DA01 DA05 DA06 4D062 BA05 BA06 BB05 CA20 DB12 DB18 DB30 EA03 EA04 EA32 FA12 FA15 FA30 4F301 AA25 BA17 BA21 BF06 BF08 BF13 BF29 BF31

Claims (4)

[Claims] 1. A method of separating a support from a heat development material containing photosensitive silver halide grains, an organic silver salt, a reducing agent and a binder on the support, wherein the area of the heat development material is converted into an area. Cutting into small pieces of 0.1 mm ^{2 to} 100 cm ² with an acid or alkali 60 containing an oxidizing agent.
Removing the coating from the support within 1 minute to 8 hours in water at ~ 140 ° C, separating the support and the coating with a filter, and heating the separated support with hot air at 40 to 100 ° C. A method for treating a used thermal developing material, comprising a step of drying. 2. An organic coagulant having a sulfonic acid group or a carboxylic acid group in an amount of 0.1 to 30% by mass is added to a coating component containing silver separated from the support and dispersed in water to precipitate. 2. The method according to claim 1, wherein the solidified composition is solidified, and the solidified composition is recovered by incineration. 3. The method according to claim 2, wherein the coagulant is selected from polymers having styrene sulfonic acid, acrylic acid, and naphthalene sulfonic acid. 4. Drying the support in the critical state of methanol, ethanol, carbon dioxide or water for 10 seconds to 180 minutes in the presence of an alkaline catalyst of 1 ppm to 60,000 ppm based on the mass of the supercritical fluid. Degradation, then 1 ppm to 6
A method for treating a spent thermal developing material, comprising: decomposing in the presence of 10,000 ppm of an acid catalyst in 10 seconds to 180 minutes, and reducing the temperature to 80 ° C. or lower within 15 minutes.