KR20190045430A - Eco-Friendly Acrylic Polymer For Photosensitive Composition Of Positive CTP Printing Plate - Google Patents

Abstract

The present invention relates to an acrylic polymer for a photosensitive composition of a positive CTP printing plate, which is produced by copolymerizing 40-60 wt% of a hardness-adjusting monomer and 40-60 wt% of a dissolution rate-adjusting monomer such that a glass transition temperature is between 70-100°C, a weight average molecular weight is between 4,000-10,000 g/mol, and a dissolution rate is between 1000-2,400 Å/sec. According to the present invention, when the acrylic polymer is used for thermal and UV positive CTP, corrosion of components of a developing device can be minimized, and a range of operating elements and conditions related to quality of development becomes wider, thereby remarkably relieving work-related stresses of an operator. In addition, a printing process of the present invention is the same as that of a conventional printing plate, such that a printing operator may not feel discomfort and unfamiliarity while using the present invention, and the existing printing equipment can be used without change.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an acrylic polymer for photosensitive compositions for environmentally positive positive CTP printing plates,

The present invention relates to an acrylic polymer for a photosensitive composition used in a positive CTP (computer to plate) printing plate, and more particularly, to an acrylic polymer for a photosensitive CTP (computer to plate) To an eco-positive positive thermal that can be developed in a low-concentration alkaline developer, and to an acrylic polymer copolymerized for use in a photosensitive composition for UV-CTP printing plates.

CTP printing, which is widely used in recent years, is a method of forming images on a printing plate by processing data with a computer and omitting the image forming process using the film. In addition, it is possible to prevent defects, for example, loss of halftone dots, foreign matter contamination, and the like, which may occur during the process of exposing a film on which an image is formed, to a printing plate.

CTP printing, which is a method of directly irradiating a printing plate with a laser, is divided into a thermal CTP and an ultra-violet CTP according to a light source used. Generally, a thermal CTP is formed near 800 to 900 nm (especially 830 nm) Of ultraviolet rays of about 360 to 420 nm (especially 405 nm) are used.

In addition, a portion of the printing plate on which the laser is applied is developed in the alkaline developer to become a non-forming portion, and a portion in which a non-laser receiving portion is developed to become a non-forming portion is defined as a negative.

The positive CTP printing plate, which is currently used in the domestic printing industry and developed with a high concentration alkaline developer, is mainly composed of phenols (phenol, cresol, xylenol, resorcinol) and aldehydes (formaldehyde, acetaldehyde, furfural) And a phenol resin such as a cresol formaldehyde novolak resin, which is a modified resin thereof, are contained in the photosensitive composition.

The phenolic resins used in the photosensitive compositions are variously mentioned in Patent Documents 10-0838149, 10-0709520, 10-1253351, 10-1553030, and Patent Application Publication 2000-0076802.

However, a conventional printing plate made of a photosensitive composition using a phenol resin is developed with a high-concentration aqueous alkaline solution to separate a silver halide portion and a non-silver halide portion. The printed halftone dot may fail depending on the fatigue, temperature and developing speed of the aqueous alkaline solution, The high-concentration alkaline solution used in the process and the water used in the wash process become alkaline wastewater, which causes environmental problems as well as treatment costs.

As a method for solving the problem of alkaline wastewater causing such an environmental problem, a method of developing with a rubber solution or water instead of a high concentration alkaline aqueous solution is disclosed in EP 1342568, PCT / EP 2005/052298, PCT / EP 2006/068303 and 10-2009-0050353 Lt; / RTI > patent.

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

Also, the manner in which an exposed printing plate is directly attached to a printing machine and developed through a normal printing process is disclosed in PCT / EP 2006/068498, US 5,922,512, and US 6,723,495.

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. Also, the dot loss due to the phenomenon may occur, and it requires higher laser energy than conventional CTP printing equipment.

In recent years, a printing method which does not require the development of a non-forming portion is disclosed in Japanese Patent Application Laid-Open Nos. 10-1191162 and 10-1152802, Japanese Patent Application Laid-Open Nos. 2004-302219, 2004-322414, -0030714.

However, in order to solve the problems caused by the use of the high-concentration alkaline developer, the methods heretofore mentioned require higher laser energy than conventionally, so that it is difficult to use in existing equipment, or paper and time are wasted more than necessary , There is a problem that the pressure resistance against the fountain solution is lower than in the prior art, or the price of the printing plate is higher than that of the conventional one.

SUMMARY OF THE INVENTION The present invention has been made to solve the above problems and it is an object of the present invention to provide a printing method and a printing apparatus which can use the printing apparatus as it is, , The use of a high-concentration alkaline developer is required to be more than 65% for thermal CTP and 75% or more for UV CTP, which is a desirable form of positive thermal and UV- It is an object of the present invention to provide an acrylic polymer for a photosensitive composition for use in a CTP printing plate.

It is an object of the present invention to provide a thermosetting resin composition which is produced by copolymerizing 40 to 60% by weight of a hardness control monomer and 40 to 60% by weight of a dissolution rate control monomer as a gist of the present invention and has a glass transition temperature of 70 to 100 ° C, To 10,000 g / mol, and a dissolution rate of 1,000 to 2,400 A / sec.

Another object of the present invention is to provide a thermosetting resin composition, wherein the hardness control monomer is selected from the group consisting of vinyltoluene, styrene, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and t- And at least one of the dissolution rate controlling monomers is selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, and methacrylic acid. Of an acrylic polymer for a photosensitive composition.

Another aspect of the present invention is to provide an acrylic polymer for a photosensitive composition of a CTP printing plate, which has a weight average molecular weight of 5,000 to 9,000 and a dissolution rate of 1,400 to 2,000 Å / sec.

Another point of the present invention is to provide a positive CTP printing plate characterized in that it comprises 3 to 5% by weight of an indol-based, cyanic-based or phthalocyanine-based dye as an infrared absorbing dye for thermal printing in a total amount of 100% by weight of the photosensitive composition To provide an acrylic polymer for a photosensitive composition.

Another point of the present invention is to provide an ultraviolet light activating agent for the Uvb printing which comprises an ester compound of 2-diazo-1-natone-5-sulfonyl chloride and polyhydroxy as an ultraviolet light activator, To 25% by weight based on the total weight of the composition.

The photosensitive composition for an eco-positive positive CTP printing plate containing the acrylic polymer of the present invention is highly environmentally friendly because it reduces the amount of alkaline wastewater discharged by a maximum of 75% or more compared with the conventional alkaline developer used in the development process.

In the case of the conventional UvB CTP printing plate, the developing solution and water are usually used in a ratio of 1: 4, and in the case of the thermal CTP printing plate, the developer solution is used without dilution. However, in the case of the Uv B CTP printing plate using the acrylic polymer of the present invention The developer and water may be used in a ratio of 1 to 20, and in the case of a thermal CTP printing plate, diluted to a ratio of 1: 2.

In addition, the replenishing liquid for the conventional printing plate requires 80 ml / m ² , but the printing plate using the acrylic polymer of the present invention is only 20 ml / m ² . In addition, there is also an advantage that the developer exchange cycle can be dramatically increased from two weeks to two months or more in the past. Therefore, it is possible to reduce the cost, time, and labor cost of the developer exchange.

In addition, diluting the developer and developer replenisher with a low alkali makes it possible to minimize the erosion of component parts and clean the developer.

In addition, the conventional developing plate has a relatively high conductivity of 70 to 90 ms, so that it is necessary to carefully manage the developing temperature and the speed to obtain desired developing quality.

However, since the printing plate including the acrylic polymer of the present invention has a considerably wide range of elements and conditions related to the developing quality, the work stress of the operator can be largely solved.

Further, since the printing process is the same as that of using the conventional printing plate, there is no inconvenience and irritation in use of the printing operator, and existing printing equipment can be used as it is.

The acrylic polymer for a photosensitive composition (hereinafter referred to as 'acrylic polymer') of a positive CTP printing plate according to the present invention should be capable of developing even in a low-concentration alkaline developer having a sufficient resistance to printing and a maximum lowering of 75% In order to secure printing intrinsic strength, the hardness and weight average molecular weight (Mw) of the acrylic polymer and the acrylic polymer weight average molecular weight and the dissolution rate are designed to be within a specific range in order to be able to develop even in a low-concentration alkaline developer. It should be copolymerized using monomers.

The acrylic polymer according to the present invention is prepared by copolymerizing 40 to 60% by weight of a hardness-adjusting monomer and 40 to 60% by weight of a dissolution rate controlling monomer. As the copolymerization method, bulk polymerization, suspension polymerization, emulsion polymerization, or solution polymerization may be used. In the present invention, solution polymerization is preferably used.

The polymerization method of the acrylic polymer includes a total amount of the monomer, initiator, and solvent to be charged into the reaction vessel, and a partial charging method in which the monomer and the initiator are slowly added to the reaction vessel. In the present invention, Easy part loading method was used.

The hardness-adjusting monomer used in the present invention is a copolymer of vinyltoluene, styrene, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, and t-butyl methacrylate having a glass transition temperature and a molecular weight as shown in Table 1 , And t-butyl acrylate.

The hardness can be expected from the acrylic polymer glass transition temperature (Tg). When the acrylic polymer is below the glass transition temperature point, it is a solid phase region. When the acrylic polymer is above the glass transition temperature point, viscous flow occurs. That is, when the glass transition temperature is high, the hardness is hard and when the glass transition temperature is low, the hardness tends to soften.

The glass transition temperature of the acrylic polymer according to the present invention should be adjusted to 70 to 100 占 폚 by appropriately selecting an acrylic monomer. When the glass transition temperature is lower than 70 ° C, the hardness is lowered to lower the pressure resistance. When the glass transition temperature is higher than 100 ° C, the hardness is too high, resulting in poor flexibility and the polymer may be broken.

As the glass transition temperature of the acrylic polymer, the glass transition temperature of the homopolymer is used as shown in Table 1 below. Experimentally, the glass transition temperature of the copolymer acrylic polymer was found to be between the glass transition temperature of the homopolymer, Calculated:

In this formula,

Tg is the glass transition temperature (absolute temperature, K) of the copolymer,

W ₁ and W ₂ are the weight ratios of the respective monomers,

Tg ₁ and Tg ₂ are the glass transition temperatures of the respective homopolymers.

Monomer Homopolymer
Tg (占 폚) Monomer
Molecular Weight

Hardness
control Vinyl toluene 101 118 Styrene 100 104 Methyl methacrylate 105 100 Ethyl methacrylate 65 114 Isobutyl methacrylate 53 142 t-butyl methacrylate 107 142 t-Butyl acrylate 43 128
Dissolution
speed
control Hydroxyethyl methacrylate 55 130 Hydroxypropyl methacrylate 26 144 Acrylic acid 106 72 Methacrylic acid 185 86

The weight average molecular weight of the acrylic polymer according to the present invention is 4,000 to 10,000 g / mol, preferably 5,000 to 9,000 g / mol. If the weight average molecular weight is less than 4,000 g / mol, the dissolution rate becomes faster than the reference and the pressure resistance is lowered. If the weight average molecular weight is 10,000 g / mol or more, the dissolution rate is remarkably slowed and the development is difficult.

The weight average molecular weight can be controlled by the polymerization method and polymerization degree of the acrylic polymer, or can be adjusted by using 0.1 to 5% by weight of dodecyl mercaptan as a molecular weight adjuster, relative to the monomer.

The dissolution rate controlling monomers used in the present invention are hydroxy ethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, and methacrylic acid having a glass transition temperature and molecular weight shown in Table 1 and having a hydroxyl group or a carboxyl group as a functional group And at least one of them is selected from the group consisting of acids. The dissolution rate of the acrylic polymer according to the present invention is controlled by appropriately selecting these monomers. In the present invention, the dissolution rate is 1,000 to 2,400 Å / sec, preferably 1,400 to 2,000 Å / sec. If the dissolution rate is less than 1,000 Å / sec, development in the low - concentration alkaline developer is not successful. If the dissolution speed is over 2,400 Å / sec, the uninfluenced part is also developed.

The acrylic polymer according to the present invention may include an infrared absorbing dye for thermal CTP printing, and the infrared absorbing dye is preferably a pigment or dye having light absorbing property in the infrared region of 700 to 1,200, A cyanine dye, and a phthalocyanine dye. The infrared absorbing dye absorbs light energy to amplify heat, and the amplified heat decomposes the acrylic polymer hydrogen bonds, thereby increasing alkali developability.

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, IR-23B and the like of PCAS, and it is preferably used in an amount of 3 to 5% by weight of the photosensitive composition.

In addition, the acrylic polymer according to the present invention may contain a photoactive compound for UV-CTP printing, and examples of the UV activator include 2-diazo-1-nitone-5-sulfonyl chloride and polyhydroxy , And the ultraviolet light activator is used in an amount of 20 to 25% by weight based on 100% by weight of the total amount of the photosensitive composition.

The ultraviolet light activator absorbs ultraviolet light of 360 to 420 nm and is activated by alkali solubility. The photoactive agent which does not absorb ultraviolet light reacts with the acrylic polymer to exhibit a dissolution inhibiting effect, which is called a coupling reaction.

Hereinafter, the present invention will be described in more detail by way of examples. However, these examples do not limit the present invention.

Example  One

100 g of vinyl toluene, 120 g of ethyl methacrylate and 380 g of t-butyl acrylate as a hardness controlling monomer, 200 g of hydroxyethyl methacrylate and 200 g of methacrylic acid as a dissolution rate regulator and 5 g of dodecyl mercaptan as a molecular weight regulator were added, To obtain 1,000 g of the acrylic polymer (referred to as 'acrylic polymer-1') according to the present invention.

Example  2

120 g of styrene, 130 g of ethyl methacrylate and 350 g of t-butyl acrylate as hardness control monomer, 100 g of hydroxyethyl methacrylate as a dissolution rate regulator, 100 g of acrylic acid and 200 g of methacrylic acid, and 3 g of dodecyl mercaptan as a molecular weight regulator And the resultant solution was added to the solution to obtain 1,000 g of the acrylic polymer (referred to as 'acrylic polymer-2') according to the present invention.

Comparative Example  One

50 g of methyl methacrylate, 50 g of ethyl methacrylate and 400 g of t-butyl acrylate as hardness control monomers were added so that the glass transition temperature, weight average molecular weight and dissolution rate were outside the scope of the present invention. 100 g of methacrylic acid, 400 g of methacrylic acid, and 10 g of dodecylmercaptan as a molecular weight regulator were added, and the resultant solution was combined with 1,000 g of the acrylic polymer (referred to as 'acrylic polymer-3') according to the present invention.

Comparative Example  2

200 g of methyl methacrylate, 100 g of ethyl methacrylate and 300 g of t-butyl acrylate as hardness adjusting monomers and 300 g of t-butyl acrylate as a hardening modifier were added so that the glass transition temperature, weight average molecular weight and dissolution rate were out of the range of the present invention. 100 g of ethyl methacrylate, 100 g of acrylic acid, 200 g of methacrylic acid, and 1 g of dodecyl mercaptan as a molecular weight regulator were added, and 1000 g of the acrylic polymer (referred to as 'acrylic polymer-4' .

Comparative Example  3

50 g of ethyl methacrylate, 450 g of t-butyl acrylate and 350 g of hydroxypropyl methacrylate as a dissolution rate controlling agent were added as hardness adjusting monomers so that the glass transition temperature, weight average molecular weight and dissolution rate were outside the range of the present invention, 150 g of acrylic acid and 5 g of dodecylmercaptan as a molecular weight regulator were added, and the resultant solution was combined with 1,000 g of the acrylic polymer (referred to as 'acrylic polymer-5') according to the present invention.

Comparative Example  4

200 g of methyl methacrylate, 120 g of isobutyl methacrylate and 280 g of t-butyl methacrylate as a hardness control monomer and a polymerization initiator were added thereto so that the glass transition temperature, weight average molecular weight and dissolution rate were outside the range of the present invention 400 g of hydroxyethyl methacrylate and 4 g of dodecylmercaptan as a molecular weight regulator were added and mixed to obtain 1,000 g of the acrylic polymer (referred to as 'acrylic polymer-6') according to the present invention.

Comparative Example  5

200 g of methyl methacrylate, 400 g of t-butyl methacrylate, and 160 g of hydroxyethyl methacrylate as a dissolution rate regulator were mixed so that the glass transition temperature, the weight average molecular weight and the dissolution rate were outside the range of the present invention , 90 g of acrylic acid, 150 g of methacrylic acid, and 1 g of dodecylmercaptan as a molecular weight regulator were added and mixed to obtain 1000 g of an acrylic polymer (referred to as 'acrylic polymer-7') according to the present invention.

The glass transition temperature, weight average molecular weight and dissolution rate of the acrylic polymer obtained in the above Examples and Comparative Examples were measured, and the results are shown in Table 2 below. The dissolution rate is a value obtained by measuring the degree of dissolution in a 2.38% Tetramethyl Ammonium Hydroxide (TMAH) developer by drying the copolymerized acrylic polymer at 110 ° C / 60 seconds.

Glass transition temperature
(Tg, ° C) Weight average molecular weight
(Mw) Dissolution rate
(Å / sec) Acrylic polymer-1 Example 1 75.2 5,800 1,650 Acrylic polymer-2 Example 2 81.6 8,400 1,820 Acrylic polymer-3 Comparative Example 1 94.2 3,000 2,060 Acrylic polymer-4 Comparative Example 2 86.3 12,000 1,820 Acrylic polymer-5 Comparative Example 3 45.3 5,200 1,710 Acrylic polymer-6 Comparative Example 4 77.4 6,300 320 Acrylic polymer-7 Comparative Example 5 106.2 11,000 1,510

Experimental Example 1 ( Preparation of positive thermal and UV CTP printing plates and image formation)

Seven kinds of acrylic polymers of the examples and comparative examples in the above Table 2 were prepared from positive thermal CTP and positive UV CTP photosensitive compositions as shown in the following Table 3 and applied to each printing plate to measure developability, ≪ / RTI > were prepared.

First, a composition according to the examples and comparative examples shown in Table 3 below was applied to an aluminum printing plate having a purity of 99.5% and a thickness of 0.27 mm, which had been subjected to degreasing, electrolytic polishing, anodizing and sealing, and dried at 105 ° C for 3 minutes, A thermal and UV printing plate was prepared.

Images were formed using a SCREEN PLATE lite 8800 positive positive CTP printing plate and a Basys UV SETTER 850 positive positive UTP CTP printing plate.

Acrylic polymer
(weight%) Infrared absorbing dye
(weight%) Dye * 1)


Thermal CTP


Example 1 Acrylic monomer-1


95.0





3.0





2.0


Example 2 Acrylic monomer-2 Comparative Example 1 Acrylic monomer-3 Comparative Example 2 Acrylic monomer-4 Comparative Example 3 Acrylic monomer-5 Comparative Example 4 Acrylic monomer-6 Comparative Example 5 Acrylic monomer-7 Acrylic polymer
(weight%) Ultraviolet light activator
(weight%) Dye * 1)


Ubuy CTP


Example 1 Acrylic monomer-1


75.8





22.7





1.5


Example 2 Acrylic monomer-2 Comparative Example 1 Acrylic monomer-3 Comparative Example 2 Acrylic monomer-4 Comparative Example 3 Acrylic monomer-5 Comparative Example 4 Acrylic monomer-6 Comparative Example 5 Acrylic monomer-7

* 1) The dye is Crystal violet.

Experimental Example 2 (Development and Conductivity Measurement)

The positive thermal CTP printing plates of Examples 1 and 2, in which the image was formed as in Experiment 1, were diluted with a stock solution of Kodak Gold Star Premium developer and water at a ratio of 1: 2, and the alkali was reduced by 65% / ≪ / RTI > for 25 seconds and then mounted on a printing press.

Further, the Positive UV CTP printing plates of Examples 1 and 2 in which images were formed were prepared by diluting the stock solution of FUJIFILM DP-4 developer and water at a ratio of 1 to 20, and measuring the degree of alkali reduction of 23 degrees / 25 seconds After development, it was mounted on a printing machine.

Conventional positive thermal CTP printing plates used Kodak Gold Star premium developer solution as it is, and conventional positive UV CTP printing plates were diluted with Fuji Film DP-4 developer solution and water at a ratio of 1: 4.

The conductivity values of the high-concentration alkaline developer used in the conventional positive CTP printing plate and the low-concentration alkaline developer used in the positive CTP printing plate containing the acrylic polymer of the present invention were measured, and the results are shown in Table 4 below.

Conventional positive CTP printing plate The positive CTP printing plate of the present invention Thermal ^{* 1)} Ubuy ^{* 2)} Thermal ^{* 3) 4)} developer
conductivity 74 ms / cm
75 ms / cm
40 ms / cm
25 ms / cm

^{* 1)} Kodak Gold Star premium developer liquid.

^{* 2)} Dilute Fuji Film DP-4 developer and water at a ratio of 1: 4.

^{* 3)} KODAK GOLD STAR Premium diluted with developing solution and water at a ratio of 1: 2.

^{* 4)} Dilute Fuji Film DP-4 developer and water at a ratio of 1: 20.

Conductivity is also used as a factor for determining the alkali concentration of the developer. As shown in Table 4, the positive CTP printing plate according to the present invention shows that it is possible to develop in a lower conductivity, that is, in a low-concentration alkaline developer. Considering that the conductivity of the seawater is usually 53 ms / cm, it can be guessed to what degree the environment-friendly effect of the present invention is.

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.

Experimental Example 3 (Printing test)

The developability, the print state and the abrasion resistance were evaluated in the following manner, and the results are shown in Table 5 below.

(Developability Evaluation)

When the developed plate was observed with naked eyes, when the image was clearly classified and the image portion was enlarged at 10 magnification, it was judged as 'good' that there was no fine hint damage.

(Evaluation of printed matter condition)

When the developed plate was mounted on a printing machine and printed, the printed image was clearly classified, and when the image was enlarged at 10 magnification, the fine dots were clearly reproduced, and the absence of scratching on the non- Respectively.

(Evaluation of Impact Resistance)

When the printed matter is continuously evaluated while the printed matter is being printed, when the image classification of the printed matter is blurred or the image portion is observed at an enlarged magnification of 10, the fine dot is damaged or scumming does not occur in the non- And the number of sheets was evaluated by printing resistance.

Developability prints
condition Impairment
(Number of prints, sheets) Thermal
CTP Example 1 Good Good 32,300 Example 2 Good Good 38,100 Comparative Example 1 A phenomenon - - Comparative Example 2 Not Developed Scumming - Comparative Example 3 Good Good 3,800 Comparative Example 4 Not Developed Scumming - Comparative Example 5 Not Developed Scumming - Ubuy
CTP Example 1 Good Good 41,400 Example 2 Good Good 45,700 Comparative Example 1 Good Good 2,900 Comparative Example 2 Not Developed Scumming - Comparative Example 3 Good Good 6,100 Comparative Example 4 Not Developed Scumming - Comparative Example 5 Not Developed Scumming -

As shown in Table 5, when a photosensitive composition for a positive thermal CTP printing plate containing an acrylic polymer according to Examples 1 and 2 of the present invention was used, a developer having an alkali of 65% lower than that of the alkali polymer outside the scope of the present invention It can be seen that the developability, the printed matter state, and the resistance against cracking are good. Comparative Example 1 was also developed in the developing line portion, and in Comparative Example 2, Comparative Example 4 and Comparative Example 5, development was poor and scratching of the ink was caused in the non-drawn portion, and the resistance measurement was stopped. In Comparative Example 3, the developability and print quality were good, but the resistance to abrasion was insufficient.

Further, according to the results shown in Table 5 above, when the photosensitive composition for a positive UV CTP printing plate containing the acrylic polymer according to Examples 1 and 2 of the present invention is used, the alkali is reduced by 75% It can be seen that developability, print quality, and resistance against cracking are good in the developed developer.

In case of Ubiquitous CTP, Comparative Example 1 and Comparative Example 3 were good in terms of developability and print quality, but had insufficient resistance to cracking. In Comparative Examples 2, 4, and 5, development was poor, and scratching of the ink on the non-wrinkled portion occurred, and the measurement of the resistance to abrasion was stopped.

The eco-friendly positive CTP printing plate of the present invention includes an acrylic polymer having a hardness suitable for printing and having a weight average molecular weight and a dissolution rate value so as to be developable even in a low-concentration alkaline developer in which alkali is reduced by at least 75% . For this reason, the discharge of alkaline wastewater is remarkably reduced by at least 75%, which is very environmentally friendly. Also, since the printing process is the same as that of the conventional positive CTP printing plate, there is no inconvenience and discomfort to the use of the printing operator and the existing printing equipment can be used as it is.

Claims (5)

A glass transition temperature of 70 to 100 占 폚, a weight average molecular weight of 4,000 to 10,000 g / mol and a dissolution rate of 1,000 to 1,000,000 g / mol, To 2,400 A / sec. ≪ / RTI >
The positive resist composition according to claim 1, wherein the hardness-adjusting monomer is one or more kinds selected from the group consisting of vinyl toluene, styrene, methyl methacrylate, ethyl methacrylate, isobutyl methacrylate, t-butyl methacrylate, and t- And the dissolution rate controlling monomer is selected from the group consisting of hydroxyethyl methacrylate, hydroxypropyl methacrylate, acrylic acid, and methacrylic acid. In the positive CTP printing plate, Acrylic polymer for compositions.
The acrylic polymer for a photosensitive composition according to claim 1, wherein the weight average molecular weight is 5,000 to 9,000 and the dissolution rate is 1,400 to 2,000 Å / sec.
The photosensitive composition according to any one of claims 1 to 3, which contains 3 to 5% by weight of an indole-based, cyanine-based or phthalocyanine-based dye as an infrared absorbing dye for a total of 100% by weight of the total amount of the photosensitive composition Acrylic polymer for.
The process according to claim 1, wherein an ester compound of 2-diazo-1-naphthone-5-sulfonyl chloride and polyhydroxy as an ultraviolet light activator for UV printing is added in an amount of 20 to 25 wt% % ≪ / RTI > of the total weight of the composition.