KR101859971B1 - Photosensitive composition for non-development positive thermal CTP printing plate - Google Patents

Abstract

The present invention relates to a photosensitive composition for a non-development positive thermal computer to plate (CTP) printing plate. The photosensitive composition for a non-development positive thermal CTP printing plate according to an embodiment of the present invention comprises a hydroxyl group resin, a carboxylic acid group resin, an acrylic acid super absorbent polymer, a block isocyanate, and an infrared absorption dye. Therefore, the photosensitive composition according to the present invention decomposes a hydrogen bond and generates micro-cracks in the surface of the non-development positive thermal CTP printing plate by irradiated infrared rays such that a portion of the non-development positive thermal CTP printing plate receiving an infrared laser through a finisher post-processing process is rapidly changed into a non-coated portion reacting against an ink. Further, the photosensitive composition according to the present invention prevents generation of wastewater or loss of halftone dots related to development as a plate for making a flat printing plate from which a development process of the non-coated portion is completely omitted. Further, the photosensitive composition according to the present invention not only is economical in the process aspect and enables an existing thermal CTP printing shutter to be used as it is since electrolytic polishing and anodizing processes can be omitted during production of a printing plate, but also is free from a limitation that an operation has to be performed in a darkroom since a photo initiator or a diazo compound is not used. Further, the photosensitive composition according to the present invention has an advantage that the composition is environmentally friendly since waste alkali solutions or solvents discharged from the development process are not used.

Description

[0001] The present invention relates to a photosensitive composition for non-developing positive thermal CTP printing plate,

The present invention relates to a photosensitive composition for a non-developing positive thermal CTP (computer to plate) printing plate, and more particularly, to a photosensitive composition for a non-developing positive thermal CTP The present invention relates to a photosensitive composition for an unnecessary non-developing positive thermal CTP printing plate.

Further, the present invention relates to a photosensitive composition for a non-developing positive thermal CTP printing plate wherein the ink repellency of the non-smoothened portion is greatly improved through a finishing process.

CTP printing, which is widely used recently due to digitization of information and high power output, is a method of forming images on a printing plate by processing data with a computer and owing to the omission of image forming process using film, have.

In addition, it is possible to prevent defects that may occur during the process of exposing a film on which an image is formed by placing the PS plate on the PS plate, for example, loss of halftone dots, mixing of foreign matter, and the like.

CTP printing, which is a method of directly irradiating the printing plate with a laser, is divided into a thermal CTP and an ultra-violet CTP according to a light source used. In general, a thermal CTP is a device for irradiating infrared rays near 800 to 900 nm And ultraviolet rays near 360 to 420 nm (especially 405 nm) are used for UV CTP.

1 (a)). In this method, ink is not applied to the portion where the laser is applied and ink is not applied to the portion where the laser is applied. (positive CTP printing) (FIG. 1 (b)).

However, CTP printing, which has the advantage of time and cost saving mentioned above, is also developed by strong alkaline aqueous solution and solvent to distinguish between the silver halide portion and the non-silver halide portion. In accordance with fatigue, temperature and developing speed of the alkaline aqueous solution and solvent, The strong alkaline aqueous solution and the solvent used in the developing process and the water used in the water washing process become wastewater, which causes processing cost and environmental problems.

As a method for solving this problem, there is disclosed in EP 1342568, PCT / EP 2005/052298, PCT / EP 2006/068303 and 10-2009-0050353 a method of developing with a rubber solution or water instead of a strong alkaline aqueous solution and a solvent.

However, in order to use the above-mentioned patented method, it is difficult to use the conventional thermal CTP equipment because it requires higher laser energy than the conventional strong alkaline aqueous solution and the printing plate which is developed with solvent.

Also, as another method of developing, a method of attaching an exposed printing plate directly to a printing machine and developing it through a normal printing process is disclosed in the PCT / EP 2006/068498, US 5,922,512, 6,723,495 patent.

This method is an on-press developing method in which the photosensitive composition of the non-irradiated portion is removed by the printing blanket roller due to the wetting liquid supplied to the printing plate and the adhesion force of the ink.

However, the meteorological phenomenon can cause paper waste until normal printing is performed due to adhesion of the wetting liquid and the ink.

In addition, it may cause dot loss due to development, and it requires higher laser energy than conventional CTP printing equipment, and there is also a limitation in working in a dark room when a photoinitiator or a diazo compound is used.

      The above-mentioned conventional non-developing thermal CTP printing plate is a vapor phase developing method in which a printing plate is developed with a rubber solution or water, or directly mounted on a printing machine and developed through a normal printing process. Finally, the non-developed thermal CTP printing plate is finally removed As a result, an aluminum support should be exposed, as shown in Fig.

In order to prevent the ink from adhering to the exposed aluminum support, it is necessary to perform electrolytic polishing which increases the surface area of aluminum, anodic oxidation to protect the polished surface, and aluminum oxide surface such as hydrophilic treatment of aluminum oxide micropores formed by anodic oxidation A processing step of treating the water with a hydrophilic treatment is required.

In recent years, in order to solve the above problem, a printing method which does not require development of a non-forming portion is disclosed in Japanese Patent Laid-Open Nos. 2004-302219, 2004-322414, and 10-2010-0030714 .

However, the above-mentioned patent methods are negative types in which the laser-receiving portion is hardened by hardening through the curing process, and when the sufficient laser energy for curing is insufficient, formation of the corrugated portion is made impossible, .

In addition, since the portion not receiving the laser should not receive ink as the non-irradiated portion, the printing plate itself must be hydrophilic.

Since the hydrophilic printing plate receives the laser beam and changes into the caulking portion through the curing process, there is a structural limitation that the non-forming portion of the caulking portion is inferior to the caulking portion even if the caulking strength of the caulking portion is sufficient.

The present invention provides a photosensitive composition for a positive thermal CTP printing plate, which has a sufficient resistance to crushing and non-curing, and which has no problems related to development such as waste water generation and halftone dot loss, It has its purpose.

It is an object of the present invention to provide a resin composition comprising a hydroxy resin capable of hydrogen bonding and a carboxylic acid resin mixture, a highly hygroscopic polymer resin for promoting ink repellency in a non-pyramid part, a block isocyanate as a heat curing agent for improving the resistance to cracking, And an infrared absorbing dye for amplifying the thermal energy of the laser.

Since the photosensitive composition for a non-developing positive thermal CTP printing plate of the present invention does not require a developing step of a non-sintered portion, it does not cause problems of waste water generation and dot loss in the developing process.

In addition, since the process of aluminum surface processing such as electrolytic polishing, anodic oxidation, and hydrophilic sealing can be omitted in the production of the printing plate, the conventional thermal CTP printing setter can be used as it is, No initiators or diazo compounds are used, so there are no restrictions on working in the darkroom.

Furthermore, there is an advantage that it is eco-friendly because no strong alkaline solution and solvent discharged from the developing process occur.

The present invention also provides a photosensitive composition for a positive-type non-developmental thermal CTP printing plate, which is a negative composition type photosensitive composition which is insufficient in hardening of a laser receiving portion and which has a lowering of internal- It is free from the structural problem of developing thermal CTP printing method.

1 is an explanatory diagram of a negative and positive thermal CTP printing method,
FIG. 2 is an explanatory view showing the effect of laser irradiation on the photosensitive composition for a positive thermal CTP printing plate of the present invention,
3 is an explanatory diagram of a printing system using a photosensitive composition for a positive thermal CTP printing plate of the present invention,
Fig. 4 is a view showing the entire process of manufacturing a thermal CTP printing plate.

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, a photosensitive composition for a positive thermal CTP printing plate according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

The photosensitive composition for a positive thermal CTP printing plate of the present invention comprises a mixture of a hydroxy-based resin capable of hydrogen bonding and a carboxylic acid group resin mixture, a highly hygroscopic polymer resin for promoting ink repulsion of non-cured portions, a block as a heat curing agent Isocyanate, and an infrared absorbing dye for amplifying thermal energy of the laser.

Each component will be described in detail as follows.

1) A mixture of a hydroxy group resin and a carboxylic acid group resin

The hydroxyl group resin and the carboxylic acid group resin are hydrogen-bondable resins. As shown in Figs. 2 and 3, on the printing plate using the photosensitive composition of the present invention containing these resins, As a result of maintaining the engagement, the penetration of the finisher is hindered, resulting in a perforated line where the ink adheres.

On the contrary, the portion of the laser which receives the laser beam breaks the hydrogen bonds due to the heat of the laser and causes fine cracks at the same time. As a result, the finisher penetrates well and has a property of pushing out the ink so that the ink is not adhered. do. (See Fig. 3)

The hydroxyl group-containing resin is preferably at least one polymer resin selected from the group consisting of cresol formaldehyde novolak and cresol phenol formaldehyde novolac, and has a weight average molecular weight of 6,000 to 20,000.

The carboxylic acid group resin is at least one polymer resin selected from the group consisting of polyacrylic acid, polymethacrylic acid, polymethyl vinyl ether maleic acid and polystyrene maleic acid, and has an acid value of 300 to 600 mgKOH / g and a weight average molecular weight of 200,000 To 2,000,000.

The hydroxy group resin and the carboxylic acid group resin are preferably mixed appropriately.

The mixing ratio of the hydroxyl group resin and the carboxylic acid group resin is preferably from 2: 8 to 3: 7. When the ratio of the hydroxyl group resin is less than 2, the resistance to decompression occurs. When the carboxylic acid group resin is less than 7, The ink repelling force of the ink is lowered.

2) Super Absorbent Polymer

The photosensitive composition for a non-developmental thermal CTP printing plate of the present invention includes a highly hygroscopic resin on a printing plate in order to increase the ink repelling force of a non-lighted portion receiving the laser.

The multi-pore high hygroscopic resin that absorbs water several hundreds to several thousand times its own weight is composed of at least one polymer selected from the group consisting of acrylic acid and methacrylic acid and is mixed with the photosensitive composition in the form of fine particles.

If the non-irradiated portion receives a laser and microscopic cracks occur as the hydrogen bond breaks, the highly hygroscopic resin rapidly absorbs water, which is the main component of the finisher used in the post-treatment process, and the ink repelling force of the non-irradiated portion is rapidly improved.

In addition, as a result of absorbing the wetting liquid supplied from the printing machine well, the ink repelling force of the non-smoothed portion is maintained even during printing.

The highly hygroscopic resin in insoluble particulate form is preferably 3 to 5% by weight in the photosensitive composition.

If it is less than 3% by weight, it takes a long time for the non-irradiated portion to have an ink repelling force, and if it is more than 5% by weight, the mixture of the photosensitive composition and the high-

The particle size of the highly hygroscopic resin is preferably 0.5 m or less, more preferably 0.2 m or less.

3) Block isocyanate

The photosensitive composition for a non-developmental thermal CTP printing plate of the present invention includes a block isocyanate for improving the resistance to cracking.

The hydrogen bonding of the hydroxy group resin and the carboxylic acid group resin alone does not have sufficient resistance to printing for printing, so that the urethane curing reaction with the isocyanate is induced, thereby ensuring a sufficient resistance against the printing.

The block isocyanate may be at least one compound selected from the group consisting of toluene diisocyanate, hexamethylene diisocyanate, methylene diphenyl diisocyanate and isophorone diisocyanate, and at least one compound selected from the group consisting of ethylene glycol, propylene glycol, trimethiol propane and pentaerythritol Reacting at least one compound selected from the group consisting of phenol, ethylacetoacetate, caprolactam and methylethylketoxime with about 3 to 15% of the isocyanate in a free state.

The blocked isocyanate preferably has no reactivity at room temperature and exhibits reactivity at a temperature between 80 and 120 ° C.

When it is reacted at a temperature lower than 80 ° C, the photosensitive composition is not easily stored. If it has a reactivity at 120 ° C or higher, sufficient reaction force may not be secured due to insufficient reaction during the process of producing a printing plate.

In order to accelerate the reaction, a urethane reaction catalyst such as dibutyltin dilaurate (DBTDL) may be used within 0.1% by weight of the photosensitive composition, and the block isocyanate is preferably 10 to 20% by weight of the photosensitive composition.

If the content is less than 10% by weight, the resistance is insufficient. If the content of the finishing agent is 20 to 30% by weight, the finishing force is excellent, but the time required for the finisher to penetrate the non- A scrambling phenomenon in which ink is applied to the front portion occurs.

4) Infrared absorbing dye

The infrared absorbing dyes are preferably pigments or dyes having a light absorbing property in the infrared region of 700 to 1,200 nm, and examples thereof include indole, cyanine and phthalocyanine dyes.

The commercially available infrared absorbing dyes include IR-140, IR-746, IR-768 perchlorate, IR-755 chloride, IR-780 iodide, IR- 786 perchlorate, IR-786, IR-792 perchlorate, IR-797 chloride, IR-797 perchlorate, IR-806, IR-813 chloride, IR-813 perchlorate, IR- 820 and FOO S0094, ADS 830AT, IR-22B and IR-23B of PCAS Co., etc., and 3 to 5% by weight of the photosensitive composition is preferable.

The infrared absorbing dye absorbs light energy to generate heat, and the heat generated decomposes the hydrogen bonds and promotes the fine cracking of the surface.

Finally, the finisher for the post-treatment of the printing plate (coated) using the photosensitive composition for a positive thermal CTP printing plate of the present invention rapidly penetrates only the portion where the laser is not received, .

As shown in FIG. 2 and FIG. 3, the hydrogen bond is broken and a fine crack is generated in the portion where the laser is received. The finishing agent penetrates into this portion, and the porous highly hygroscopic resin contained in the photosensitive composition quickly reaches the finisher The ink is pushed out by absorbing the main component water.

The finisher preferably has a pH of 8 to 9, and is preferably an aqueous solution of 1 to 2% by weight of phosphoric acid, 1 to 5% by weight of gum acacia, and 5 to 10% by weight of dextrin.

Separate photosensitive compositions were prepared by varying the mixing ratios of the components 1) to 4) and applied to each of the printing plates to produce printing plates of Examples and Comparative Examples, and printing tests were conducted on the printing plates.

Specifically, the process for producing and testing a positive development positive thermal CTP printing plate for confirming the performance of the photosensitive composition according to the present invention is as follows.

First, the aluminum support having a purity of 99.5% and a thickness of 0.27 mm was degreased, coated with the photosensitive composition shown in Table 1 below without a hydrophilic treatment, and dried at 130 ° C for 3 minutes.

The prepared printing plate was formed by using a Trendsetter 800 (Thermal CTP setter) manufactured by Creos.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Hydroxy resin
/ Carboxylic acid group resin (ratio) 3: 7 2: 8 2: 8 5: 5 3: 7 3: 7 2: 8 Hydroxy resin (% by weight) 24 16 15 38 23 25 12 Carboxylic acid group resin (% by weight) 56 61 57 39 56 60 48 High hygroscopic resin (% by weight) 5 3 3 3 One 5 5 Block isocyanate
(weight%) 10 15 20 15 15 5 30 Infrared absorbing dye (% by weight) 5 5 5 5 5 5 5

An image of 1.5% by weight of phosphoric acid, 2.5% by weight of gum acacia and 7.5% by weight of dextrin was applied to a printing plate having an image formed thereon as a finisher for 10 to 20 seconds and post-treated.

At this time, an aqueous solution in which 10 wt% of isopropanol was mixed was used as the wetting solution used in the printing machine.

The ink sensitivity, the scrambling phenomenon, and the resistance to inking of the wire were checked. The results are shown in Table 2.

Example 1 Example 2 Example 3 Comparative Example 1 Comparative Example 2 Comparative Example 3 Comparative Example 4 Ink sensitivity good good good good good Poor usually Scrambling none none none has exist has exist none has exist Impact resistance (number of copies, sheets) 60,700 57,200 62,300 - - 3,200 -

According to the results shown in the above Table 2, when the photosensitive composition for a positive thermal CTP printing plate of the present invention is used, all the improvement effects are obtained in the ink-line ink sensitivity, non-smoothing part scoring,

In the case of Comparative Example 1, Comparative Example 2 and Comparative Example 4, scratching of the ink on the non-formed portion occurred, and the measurement of the resistance to abrasion was stopped.

Since the photosensitive composition of the present invention has an adhesive force suitable for printing, the development of the non-drawn portion is not required. Therefore, the uniform surface and the surface area thereof are increased to enhance the water retentivity and deadening treatment effect and to improve the adhesive strength between the photosensitive liquid and the aluminum support An electrolytic polishing process, an aluminum oxide film after polishing, an anodic oxidation process which improves the strength of the support and a hydrophilic layer, and the sealing can be reduced or omitted. (The steps in the dotted line block in Fig. 4 are omitted)

The existing printing plate production process usually consists of 19 steps or more. (See Fig. 4)

However, since the printing plate containing the photosensitive composition according to the present invention has an adhesive force suitable for printing, the photosensitive composition does not need to develop the non-drawn portion, thereby increasing the uniform surface and the surface area, An aluminum electrolytic polishing process for enhancing the adhesion between the aluminum support and the aluminum support, and an aluminum oxidation coating after polishing to improve the strength of the support and the anodic oxidation process to produce a hydrophilic layer, and to reduce or eliminate the seals.

Accordingly, the printing plate manufacturing process of the present invention can omit the process included in the dotted line block in FIG. 4, thereby reducing the total printing plate production process to 10 or less.

Therefore, compared to the existing production process, the production equipment cost and electricity consumption can be reduced by more than 50%, and the production speed can be improved more than twice as compared with the existing production process.

In addition, the electrolytic polishing and the anodic oxidation process can be reduced or eliminated, and an expensive high-purity aluminum support which is easy to polish can be omitted.

In other words, synthetic resin sheet or other metal material can be used as a support.

This means that the cost saving effect is significant compared with the conventional method.

In recent years, the demand for cheap, stable and environmentally friendly printing plates has been steadily increasing due to the high price of printing plates in the global printing market. In accordance with this circumstance, the present invention, by omitting the developing process, It is possible to use environmentally friendly, existing thermal CTP printing setter equipments, and to produce low cost printing discs.

Claims (5)

 70 to 84% by weight of a mixture of a hydroxy group resin and a carboxylic acid group resin having a weight ratio of 2: 8 to 3: 7, 3 to 5% by weight of a highly hygroscopic resin, 10 to 20% by weight of a block isocyanate, 5% by weight based on the total weight of the photothermographic material. The method according to claim 1,
Wherein the hydroxyl group resin is composed of at least one polymer resin selected from the group consisting of cresol formaldehyde novolac and cresol phenol formaldehyde novolak, the weight average molecular weight of the selected resin is 6,000 to 20,000, and the carboxylic acid group resin is at least A resin containing at least one carboxylic acid group and at least one polymer resin selected from the group consisting of polymethyl vinyl ether maleic acid and polystyrene maleic acid, wherein the resin selected has an acid value of 300 to 600 mg KOH / g and a weight average molecular weight of 200,000 To 2,000,000. ≪ RTI ID = 0.0 > 8. < / RTI >
delete delete The method according to claim 1,
The block isocyanate may be at least one compound selected from the group consisting of toluene diisocyanate, hexamethylene diisocyanate, methylene diphenyl diisocyanate and isophorone diisocyanate, and at least one compound selected from the group consisting of ethylene glycol, propylene glycol, trimethiol propane and pentaerythritol And at least one compound selected from the group consisting of phenol, ethylacetoacetate, caprolactam, and methylethylketoxime is blocked in an amount of about 3 to 15% By weight based on the total weight of the photothermographic material.

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