JP2007224391A - Method for regenerating used planographic printing plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain, in high yield, a high-purity aluminum raw material from a used planographic printing plate and also to prevent leakage of printed information in a regeneration treatment. <P>SOLUTION: In the method for regenerating a used planographic printing plate, the used planographic printing plate after the completion of printing, in which an aluminum sheet is used as a support for providing an image recording layer thereon, is melted in a melting furnace to obtain molten aluminum and the molten aluminum is recycled as a raw material for the support. The regenerating method comprises the following steps: a recovery step 10 where the used planographic printing plate is recovered in a recovery box; an ink removal step 12 where the recovered planographic printing plate is washed with a neutral aqueous solution containing an organic solvent and a surfactant to remove the ink adhering to the image recording layer; a cutting step 14 where the planographic printing plate after the removal of the ink is finely divided into small pieces; a mixing/compression step 16 where the small pieces are mixed and/or compressed; and a melting step 18 where the small pieces after the mixing/compression step are melted in the melting furnace. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a method for recycling a used lithographic printing plate, and in particular, to obtain a high-purity aluminum raw material (recycled metal for producing an aluminum support) from a used lithographic printing plate in a high yield. The present invention relates to a technique for preventing leakage of print information during reproduction processing.

  Since a lithographic printing plate support is required to have high surface hydrophilicity, a high-purity aluminum plate is usually used. That is, a lithographic printing plate is produced by providing an image recording layer on the surface of an aluminum support obtained by subjecting an aluminum plate to a roughening treatment such as brushing or electrolytic treatment, and printing on the image recording layer through exposure and development. After the information is recorded, it is mounted on a printing machine and printing is performed by supplying ink and dampening water.

  After being used for printing, it is possible to obtain high-purity aluminum recycled ingots from used lithographic printing plates in high yield and reuse them again as raw materials for aluminum supports. Become important. In addition, since confidential information may be recorded on the image recording layer of the lithographic printing plate, it is important that confidential information does not leak in the reproduction processing of the used lithographic printing plate.

For example, Patent Document 1 discloses a conventional method for recycling a used lithographic printing plate. In Patent Document 1, a polishing liquid containing a polishing pumice containing an Si component is supplied in order to remove ink and the remaining recording layer. A method of treating with an abrasive brush is described.
JP 2005-186415 A

  However, in the case of the method for regenerating a used lithographic printing plate of Patent Document 1, since the aluminum support itself is simultaneously polished, the yield to be recovered is lowered. Further, since the polishing pumice may remain on the lithographic printing plate surface, it mixes with aluminum during melting in the melting furnace and causes a decrease in aluminum purity.

  Further, there is a chemical treatment method (magazine Altopia, April 2003, page 9) that removes the ink and remaining recording layer with acid or alkali instead of the polishing method of Patent Document 1, but the aluminum support itself. Are also etched, and the yield to be recovered decreases. Polishing the image recording layer improves the purity of the aluminum by removing the ink and the recording layer, and also prevents leakage of confidential information. There is a problem of lowering.

  The present invention has been made in view of such circumstances, and can obtain a high-purity aluminum raw material in a high yield from a used lithographic printing plate, and prevent leakage of printing information in a reproduction process. It is an object of the present invention to provide a method for recycling used lithographic printing plates.

  In order to achieve the above object, an aluminum plate is used as a support for providing an image recording layer, and the used lithographic printing plate after printing is melted in a melting furnace to obtain a molten aluminum. In the method for regenerating a used lithographic printing plate in which the molten aluminum is reused as a support raw material, a slicing step of slicing the lithographic printing plate before melting in the melting furnace, and the strip And a mixing / compressing step of mixing and / or compressing the formed strips. A method for regenerating a used lithographic printing plate is provided.

  According to the present invention, since the lithographic printing plate is fragmented before the used lithographic printing plate is melted in the melting furnace and then melted in the melting furnace, the melting efficiency is improved. The ink used in the image recording layer and printing is easily burned and removed. Therefore, it is not necessary to perform a process for removing the image recording layer and ink as in the prior art, or even if it is performed, a light treatment can be performed, so that a high-purity aluminum recycled metal can be obtained in a high yield. .

  Further, by mixing and / or compressing strips obtained by stripping a used lithographic printing plate, even if confidential information or the like is recorded on the image recording layer, there is no leakage in the reproduction process. That is, if the strips are mixed, the connection between the strips can be unknown, and if the strips are compressed into blocks, only the surface of the block can be seen.

  In addition, as a means for making a planographic printing plate into pieces, an appropriate cutting means is appropriately selected from a cutting device using a guillotine blade, a cutting device using a rotary blade, a press cutting device, a laser cutting device, a water jet cutting device, a pulverizer, etc. can do.

  A second aspect is characterized in that, in the first aspect, the strip is a strip-shaped strip having a short side of 0.5 to 10 cm.

  If strips are strips with a short side of 0.5 to 10 cm, they can be mixed without being entangled if they are mixed weakly when mixed together. This makes it easy to handle. However, if the short side of the strip is in a string shape thinner than 0.5 cm, even if it is weakly mixed, the strips are too entangled and cannot be mixed. Also, when compressing the strip, if the short side of the strip is 0.5 to 10 cm, the workability is good because it can be pressed after making it into one lump, but the short side of the cut piece If it becomes a string shape thinner than 0.5 cm, it becomes difficult to handle even when strip strips are too entangled and pressed. In order to obtain strip-like strips, a cutting device using a guillotine blade is preferable.

  An ink for removing an ink adhering to the image recording layer by washing the planographic printing plate with a neutral aqueous solution containing an organic solvent and a surfactant before or after the cutting step. A recycling method for a used lithographic printing plate, characterized in that a removing step is provided.

  The third aspect is particularly important when the ink contains a heavy metal such as pigment ink. This is because heavy metals remain during the melting treatment in the melting furnace and are mixed into the molten aluminum, causing a decrease in aluminum purity. Therefore, the lithographic printing plate may be washed with a neutral aqueous solution containing an organic solvent and a surfactant to remove ink adhering to the image recording layer. Unlike washing with acid or alkali, washing with an organic solvent and a surfactant does not dissolve the aluminum support itself, so the yield does not decrease.

  According to a fourth aspect of the present invention, in order to achieve the above object, an aluminum plate is used as a support for providing an image recording layer, and a used lithographic printing plate after printing is melted in a melting furnace to obtain a molten aluminum. In the recycling method of a used lithographic printing plate in which the molten aluminum is reused as a support raw material, a recovery step of recovering the used lithographic printing plate in a recovery box, and the recovered lithographic printing plate as an organic solvent And a neutral aqueous solution containing a surfactant to remove the ink adhered to the image recording layer, a stripping step to strip the lithographic printing plate from which the ink has been removed, Use comprising: a mixing / compressing step of mixing and / or compressing the strips that have been cut into pieces, and a melting step of melting the strips that have undergone the mixing / compression step in a melting furnace To provide a method of reproduction only lithographic printing plate.

  The fourth aspect of the present invention shows the entire steps of the method for regenerating a used lithographic printing plate. First, the used lithographic printing plate is collected in a collection box. Next, the recovered lithographic printing plate is treated with an organic solvent and a surfactant to remove ink adhering to the image recording layer. This is because, as described above, the purity of the aluminum ingot dissolved in the melting furnace is lowered when a heavy metal is contained as a kind of ink at the time of printing, such as pigment ink.

  Next, the lithographic printing plate from which the ink has been removed is cut into strips to obtain strips (including strips), which are mixed and / or compressed and then melted in a melting furnace. As a result, it is possible to obtain a high-purity aluminum recycled metal in a high yield from a used lithographic printing plate and to prevent leakage of printing information in the recycling process.

  A fifth aspect of the present invention is characterized in that, in the fourth aspect, the strip is a strip-shaped strip having a short side of 0.5 to 10 cm. Thereby, the effect described in claim 2 can be obtained.

  A sixth aspect of the present invention provides the lid of the collection box according to the fourth or fifth aspect, wherein a key for preventing the opening and closing is provided, and the transport of the used lithographic printing plate between the steps is performed in a transport container with the lid locked. It is characterized by that.

  As in claim 6, the lid of the collection box is provided with a key for preventing opening and closing, and the transport of the used lithographic printing plate between each step is performed in a transport container with the lid locked, It is possible to more reliably prevent leakage of confidential information in the reproduction process.

A seventh aspect according to any one of the fourth to sixth aspects, wherein in the ink removing step, the ink is removed such that an ink adhesion amount per surface (surface of the image recording layer) of the planographic printing plate is 1 g / m ² or less. It is characterized by that.

When the lithographic printing plate is cut into small pieces and then efficiently dissolved in a melting furnace, the effect on the aluminum purity can be achieved by removing the lithographic printing plate so that the amount of ink adhering to the surface of the lithographic printing plate is 1 g / m ² or less. Therefore, the processing time of the ink removing process can be shortened as compared with the case where the ink is completely removed.

  A high-purity aluminum raw material can be obtained in a high yield from a used lithographic printing plate, and leakage of printing information can be prevented in the reproduction process.

  Hereinafter, preferred embodiments of a method for regenerating a printed planographic printing plate according to the present invention will be described in detail with reference to the accompanying drawings.

  FIG. 1 shows each step of the reproduction method of a printed planographic printing plate according to the present invention, and each step will be described in detail below. In the fragmentation step, as described above, an appropriate cutting means is appropriately selected from a cutting device using a guillotine blade, a cutting device using a rotary blade, a press cutting device, a laser cutting device, a forter jet cutting device, a pulverizer, and the like. However, in the present embodiment, a description will be given of a cutting process in which a lithographic printing plate is cut with a guillotine device to form strips.

[Recovery process]
The used lithographic printing plate is first recovered in a recovery box 10 with a lock in the recovery step 10. There are multiple types of collection boxes depending on the size (vertical / horizontal) of the planographic printing plate. The collection box is composed of a box body, an opening / closing lid, and a key. After the planographic printing plate is collected and stacked in a bundle in the box body, it is stored in a locked state so that the opening / closing lid does not open. . This prevents leakage of confidential information recorded on the image forming layer of the lithographic printing plate.

[Ink removal process]
Prior to the ink removing step 12, it is preferable to remove dirt and dust adhering to the collected used lithographic printing plate. As a method for removing the deposits, for example, high-pressure air blow, water washing, brushing to such an extent that the aluminum support itself is not damaged can be performed. Thereby, it is possible to prevent impurities from being mixed into the neutral aqueous solution in the ink removing step 12.

  The ink removal step 12 is particularly important in order to prevent the aluminum purity of the regenerated aluminum raw material from being lowered when an ink containing a heavy metal such as a pigment ink is used as an ink when printing a lithographic printing plate. Therefore, if the ink does not contain heavy metal and can be burned at the time of melting in the melting furnace, the ink removing step can be omitted.

  This ink removing step 12 is a step of washing the used lithographic printing plate with a neutral aqueous solution containing an organic solvent and a surfactant. The neutral aqueous solution used here includes an organic solvent that dissolves ink but does not dissolve aluminum, a surfactant that solubilizes the organic solvent in water, and water as a solvent. The neutral aqueous solution preferably has a pH in the range of 5.0 to 9.0. As the organic solvent used for the neutral aqueous solution, benzyl alcohol, 2-phenoxyethanol, 2-anilinoethanol and the like can be suitably used, and among them, benzyl alcohol is particularly preferable.

  The amount of the organic solvent in the neutral aqueous solution can be appropriately selected depending on the type of ink and the amount of ink adhered, but is preferably in the range of 10 to 45% by mass, more preferably 15 to 40% by mass in terms of solid content. Range.

  The amount of the surfactant contained in the neutral aqueous solution is not particularly limited as long as the organic solvent to be used can be solubilized in about 40 to 100% by mass of water or an aqueous solvent, and the anionic surfactant is not limited. , Any of amphoteric surfactants, nonionic surfactants, and cationic surfactants may be used. From the viewpoint of solubility of the organic solvent, an anionic surfactant is particularly preferable, and examples thereof include alkylaryl sulfonates, alkane sulfonates, and aliphatic salts, and sodium butylnaphthalene sulfonate is particularly preferable.

  The amount of the surfactant in the neutral aqueous solution can be appropriately selected depending on the type and amount of the organic solvent to be used in combination, but is preferably in the range of 10 to 45% by mass, more preferably solid content. 15 to 40% by mass. In the above preferred range, the solubility of the organic solvent can be secured and high ink removability can be obtained.

  In the neutral aqueous solution, in addition to the above-mentioned organic solvent, surfactant, and water as a solvent, various combined components depending on the purpose, such as an antifoaming agent, a pH adjusting agent, a viscosity adjusting agent, a crate agent, etc. Can be used.

  Examples of the ink removal method of the used lithographic printing plate with a neutral aqueous solution include a method of immersing a used lithographic printing plate in a neutral aqueous solution, and a method of spraying or showering the neutral aqueous solution on the surface of the used lithographic printing plate. It can be adopted as appropriate.

  As immersion conditions, it is preferable to immerse in a bath filled with a neutral aqueous solution of 15 to 45 ° C. for 20 to 300 minutes. From the viewpoint of ink removal efficiency, it is preferable to apply mechanical vibration or ultrasonic vibration during immersion, to blow a gas into the bathtub and to bubble, or to stir the inside of the bathtub with a stirrer. The immersion may be performed by immersing a plurality of used lithographic printing plates at a time, or may be performed by conveying the used lithographic printing plates one by one so as to pass through the bath.

  When the ink removal of the used lithographic printing plate with the neutral aqueous solution is completed, it is preferable to perform a washing treatment for washing away the neutral aqueous solution from the used lithographic printing plate. For example, a method of rubbing with a nylon brush or the like while spraying washing water on the image recording layer surface of the used lithographic printing plate with a spray or the like, and a method of allowing the lithographic printing plate to be conveyed in a water bath are suitable for the washing treatment. Can be used. The washed lithographic printing plate is preferably dried by a known method such as a non-contact heater drier, an air knife drier, a hot air blowing drier, or the like.

By the above ink removing process, the ink adhering to the image recording layer of the used lithographic printing plate is removed. In this case, it is preferable to remove the ink so that the ink adhesion amount per surface (image recording layer surface) of the planographic printing plate is 1 g / m ² or less. Therefore, a step of detecting the ink adhesion amount may be provided after the ink removal step.

  In the present embodiment, the ink removing step is performed before the next cutting step, but may be performed after the cutting step.

[Cutting process]
The cutting step 14 is a step of cutting the used lithographic printing plate after the ink removing step 12 into strip-like strips. A known cutter can be used, but a guillotine type cutter suitable for cutting a plurality of used lithographic printing plates in a stacked state is preferable.

  Since the lithographic printing plate is cut into strips before the used lithographic printing plate is melted in the melting furnace and then melted in the melting furnace, the melting efficiency is improved, so the image recording layer coated with the resin-based coating liquid Ink used during printing is easily burned and removed. Therefore, it is not necessary to perform a process for removing the image recording layer and the ink as in the prior art, or even if it is performed, a light treatment is sufficient, so that a high-purity aluminum raw material can be obtained in a high yield.

  The size of the strip-shaped strip after being cut is preferably a strip having a short side of 0.5 to 10 cm. If the short side of the strip is 0.5 to 30 cm, in the next mixing / compression step 16, when the strips are mixed, if they are mixed weakly, they can be mixed without being entangled. Yes, when intensively mixed, it becomes moderately intertwined into a bowl-like lump, which makes handling easier. Therefore, in mixing, the band strips are first mixed weakly so that they do not entangle with each other, and the strip strips are mixed to prevent leakage of confidential information. It is better to improve handling.

  By the way, if the short side of the strip is thinner than 0.5 cm, not only the strips are entangled with each other even if they are weakly mixed, and the handling becomes worse. Also, when the strip is compressed into a block (block), if the strip has a short side of 0.5 to 10 cm, it can be pressed and then pressed to improve workability. Although it is good, if the short side of the strip-like strip becomes a string shape thinner than 0.5 cm, the strip-like strips are too entangled and difficult to handle even when pressed. The length of the short side of the strip is more preferably in the range of 1 to 10 cm.

  The length of the long side of the strip is preferably 10 to 140 cm, and more preferably 20 to 50 cm. This is because if the length of the long side of the strip-like strip is too long, mixing and compression become difficult, and handling properties also deteriorate.

  Note that the size of the short side and the long side of the strips within the above-mentioned range can be appropriately changed depending on the importance of confidential information recorded on the image recording layer of the used lithographic printing plate. it can. In short, leakage of confidential information can be prevented, handling properties can be improved, and further, stripping can be performed to such an extent that the strip efficiency can be improved when the strip strip is melted in a melting furnace described later.

[Mixing / compression process]
In the mixing / compressing step 16, the used lithographic printing plate that has been cut into strips is mixed as described above, and after being mixed into a block by a press machine, the next lithographic printing plate is subjected to the dissolving step 18, which is the next step. Be transported. In addition, it is not limited to performing both of mixing / compression, You may convey to the melt | dissolution process 18 what performed only mixing and made into one lump. Or you may convey to the melt | dissolution process 18 what performed only compression and made into a block. Any one of the mixing / compression processes contributes to prevention of leakage of confidential information and facilitates handling.

  Rather than a stirrer equipped with a paddle, a rotating drum type mixing device that rotates the container with the strips placed in the container can be suitably used as the mixing apparatus. That is, the strips are mixed by rotating the rotating drum in a state where a large number of strips are put in the rotating drum. In this case, it is preferable that the rotating drum rotates while being inclined at about 45 degrees rather than horizontally. Moreover, it is also possible not to provide a special mixing device by rotating a transport container that transports between processes supported by a rotating device.

  Moreover, as a press machine for compression, what can form a square block is preferable by compressing with a press plate from the top in the state which put many strip-shaped strips in the square-shaped press container. The weight of the block formed by mixing or compressing a large number of strip-like pieces is preferably about 1 kg or more and 10 kg or less for ease of handling.

  The conveyance up to the melting step 18 is preferably performed in a conveyance container (for example, a steel iron with a lid) that can lock the lid. This is because leakage of confidential information during transportation can be prevented. In addition, it is preferable to carry out not only the conveyance between the mixing / compression process 16 and the melt | dissolution process 18 but the conveyance container which can lock a lid | cover between each process.

[Dissolution process]
The strip-like strips (including those formed into blocks) conveyed to the melting step 18 are melted in a melting furnace to obtain a new aluminum raw material by using molten aluminum. In the present invention, as described above, the melting efficiency can be improved by fragmenting the lithographic printing plate before melting the used lithographic printing plate in the melting furnace and then melting it in the melting furnace.

  The obtained molten aluminum is preferably subjected to a molten metal treatment. The molten metal treatment is performed for the purpose of removing non-metallic impurities, combustion gases, oxides, and the like, and removing hydrogen gas and sodium dissolved in aluminum. As a method for the molten metal treatment, known methods such as flux, gas, and filter can be used. Among these, a two-stage molten metal treatment in which a molten metal treatment using a gas is performed in the first molten metal treatment tank and then a molten metal treatment using a filter is performed in the second molten metal treatment tank is preferable.

Example 1
In Example 1 of the present invention, a used lithographic printing plate (HN-N manufactured by Fuji Photo Film) having a length of 1300 mm, a width of 1000 mm, and a thickness of 0.3 mm is collected in the collection box in the collection step 10 and then the ink is removed. In step 12, the ink adhesion amount (ink: Eco-pure SOY, indigo (manufactured by Sakata INKS)) was reduced to 0.5 g / m ² . In the cutting step 14, this lithographic printing plate was cut with a guillotine-type cutting machine in a state where 100 sheets were laminated to form a strip-like strip having a short side of 3 cm and a long side of 40 cm. Next, in the mixing / compression step 16, the strips were mixed by rotating the transport container with a rotating device in a state where a large number of strips were placed in the transport container. The strip-like strip taken out from the transport container was pressed into a square block by a press. The block was transferred to a melting furnace with a transfer container, and then charged into the melting furnace to be melted. As a result, an aluminum raw material was obtained.

  Table 1 examined the yield and purity of aluminum raw materials obtained by melting in a melting furnace.

  Comparative Example 1 in Table 1 is a case where the ink and recording layer of the used lithographic printing plate were removed by a polishing pumice containing an Si component and then dissolved in a melting furnace without being stripped.

  Comparative Example 2 in Table 1 is a case where the ink and recording layer of the used lithographic printing plate were removed by etching with an alkaline solution and then dissolved in a melting furnace without being cut into pieces.

  As can be seen from the results in Table 1, Example 1 of the present invention has an aluminum raw material yield of 97.25%, compared with 94.55% of Comparative Example 1 and 89.52% of Comparative Example 2. It was a good result. Further, regarding the purity of the aluminum raw material, Example 1 of the present invention had the same purity as the lithographic printing plate before printing, and there was no problem at all. Thus, according to the present invention, it is possible to recycle “Product to Product”, particularly to a lithographic printing plate.

  On the other hand, the purity of Comparative Example 1 slightly decreased the purity of aluminum, and conversely, the purity of silicon (Si) slightly increased. This is considered because the polishing pumice was mixed in the molten aluminum. The purity of Comparative Example 2 was equivalent to that of Example 1.

（実施例２）
実施例２では、実施例１と同様に長さ１３００ｍｍ、幅１０００ｍｍ、厚さ０．３ｍｍの使用済み平版印刷版について上述した図１のステップを行ったときのハンドリング性及び再生処理時における機密情報の漏洩防止効果を調べたものである。裁断片は短辺３ｃｍ、長辺４０ｃｍの帯状の裁断片とした。搬送容器としては、蓋なしの鉄籠の場合と、蓋及び鍵つきに鉄籠の２種類で行った。

(Example 2)
In the second embodiment, as in the first embodiment, the handling property when the above-described step of FIG. 1 is performed on the used lithographic printing plate having a length of 1300 mm, a width of 1000 mm, and a thickness of 0.3 mm, and confidential information at the time of reproduction processing are performed. The leakage prevention effect was investigated. The cut piece was a strip-like cut piece having a short side of 3 cm and a long side of 40 cm. As the transport container, two types of iron cages with a lid and a key were used.

  In Table 2, Example 2-1 is a case where the cut pieces are mixed, and Example 2-2 is a case where the cut pieces are compressed and blocked.

  In Comparative Example 3, the cutting process 14 and the mixing / compressing process 16 are not performed, but the dissolving process 18 is immediately performed from the ink removing process 12, and the used lithographic printing plate is kept in the above size. This is a case where the iron plate is conveyed by a iron plate (iron plate having the size of a lithographic printing plate).

  The comparison results are shown in Table 2. The handling property was determined by visual observation for ease of transport, load collapse during transport, spillage during transport, loading workability at the time of charging into the melting furnace, and the like. In addition, the effect of preventing leakage of confidential information was determined by placing a determiner at each step to determine whether the contents recorded on the image recording layer of the planographic printing plate can be read visually during the reproduction process.

  As can be seen from the results in Table 2, Example 2-1 of the present invention was good in both handling properties and the effect of preventing leakage of confidential information. In particular, Example 2-2 in which the cut pieces were blocked had better handling properties than Example 2-2 in which the cut pieces were mixed. Further, when the cut piece had a short side of 3 cm and a long side of 40 cm, the cut piece did not dance when the melting furnace was put in, and the charging workability was good.

  On the other hand, in Comparative Example 3, since the size of the lithographic printing plate was large during handling, it was easy to collapse the load in the iron slag, so that it could not be smoothly conveyed, and because it was too large, it was put into the melting furnace Workability was also poor. Moreover, since the comparative example 3 was processed at each process, without being fragmented, and conveyed between each process, the leakage prevention effect of confidential information was bad.

（実施例３）
実施例３は、感光層面に合紙が合わされた使用済みの平版印刷版を使用し、細片化手段として実施例１と同様にギロチン方式の裁断機で裁断した場合と、粉砕機で粉砕した場合とで、平版印刷版からの合紙の剥離性を比較した。これは、合紙が剥離せずに溶解炉に持ち込まれると、溶解炉で溶解して得られたアルミニウム原材料の収率、純度の低下要因となるからである。

(Example 3)
In Example 3, a used lithographic printing plate having a slip sheet on the surface of the photosensitive layer was used and, as a stripping means, cut with a guillotine type cutting machine as in Example 1 and pulverized with a pulverizer In some cases, the peelability of the slip sheet from the planographic printing plate was compared. This is because if the interleaving paper is brought into the melting furnace without being peeled, it becomes a cause of lowering the yield and purity of the aluminum raw material obtained by melting in the melting furnace.

  As a result, the release of the slip sheet from the planographic printing plate was better when the planographic printing plate with slip paper was shredded with a pulverizer than with the guillotine cutter.

Explanatory drawing explaining each process of the reproduction method of the used lithographic printing plate which concerns on this invention

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... Recovery process, 12 ... Ink removal process, 14 ... Cutting process, 16 ... Mixing / compression process, 18 ... Dissolution process

Claims (7)

An aluminum plate is used as a support for providing an image recording layer, and a used lithographic printing plate after printing is melted in a melting furnace to obtain a molten aluminum, and the molten aluminum is reused as a support raw material In the reproduction method of used lithographic printing plates,
A stripping step for stripping the planographic printing plate before melting in the melting furnace;
A method for regenerating a used lithographic printing plate, comprising at least a mixing / compressing step of mixing and / or compressing the strips.   The method for regenerating a used lithographic printing plate according to claim 1, wherein the strip is a strip-shaped strip having a short side of 0.5 to 10 cm.   An ink removing step is provided to remove the ink adhering to the image recording layer by washing the lithographic printing plate with a neutral aqueous solution containing an organic solvent and a surfactant before or after the stripping step. A method for regenerating a used lithographic printing plate according to claim 1 or 2. An aluminum plate is used as a support for providing an image recording layer, and a used lithographic printing plate after printing is melted in a melting furnace to obtain a molten aluminum, and the molten aluminum is reused as a support raw material In the reproduction method of used lithographic printing plates,
A recovery step of recovering the used lithographic printing plate in a recovery box;
An ink removing step of washing the collected lithographic printing plate with a neutral aqueous solution containing an organic solvent and a surfactant to remove ink adhering to the image recording layer;
A stripping step for stripping the lithographic printing plate from which the ink has been removed;
A mixing / compressing step of mixing and / or compressing said strips;
A method for regenerating a used lithographic printing plate, comprising: a melting step of melting the strips that have undergone the mixing and compression step in a melting furnace.   The method for regenerating a used lithographic printing plate according to claim 4, wherein the strip is a strip-shaped strip having a short side of 0.5 to 10 cm.   The lid of the collection box is provided with a key for preventing opening and closing, and the transport of the used lithographic printing plate between the processes is performed in a transport container with the lid locked. How to recycle used lithographic printing plates. The regeneration of a used lithographic printing plate according to any one of claims 4 to 6, wherein in the ink removing step, the ink is removed so that an ink adhesion amount per surface of the lithographic printing plate is 1 g / m ² or less. Method.

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