A modified colorant, and a preparation method and application thereof

Abstract

The present application provides a modified color dye, its preparation method and application. The composition of the present application contains the modified color dye, and the structure contains a naphthalene sulfonic acid group. Compared with conventional color dyes, the modified color dye can form a hydrogen bond with the oxygen atom in the photosensitive combination. On the other hand, the modified color dye has a large molecular weight and a small binding force with aluminum. After development, there is no residual color in the blank area. The modified color dye has the characteristics of high photosensitivity and mild development conditions, thereby effectively improving the dot quality of the plate material, which is beneficial to ensure the image reproduction and precision. At the same time, due to the mild development conditions, the amount of sludge residue after development is greatly reduced.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of photosensitive compositions, in particular, the present application relates to a modified color dye, a preparation method and application thereof, a photosensitive composition of the modified color dye and application of the photosensitive composition in positive thermal CTP plate. BACKGROUND

[0002] In recent years, computer-to-plate (CTP) technology is gradually popularized in the printing field. At present, the thermal sensitive technology of CTP plate is relatively mature, mainly applied to newspaper industry, books and commercial printing, and has a high market share and is widely used by users. Some printed products have very high requirements on the performance of the plate, high sensitivity, large development tolerance and good small dot restoration. The photosensitive composition technology plays an important role in plate making.

[0003] A complete thermal plate photosensitive composition mainly contains alkali-soluble resin, dissolution inhibitor, development promoter, color dye and sensitizing dye, etc. In order to increase the visibility of the image after plate making of the thermal plate, facilitate the visual inspection or image analysis of the performance of the plate after plate making of the thermal plate, a color dye is added to the composition. The color dye can be a salt dye, an oil-soluble dye and an alkali dye. These compounds can be used alone or in mixture. The composition of US6391524 and US6461795 contains a cationic triarylmethane dye, which colors the image of the thermal plate. WO2009047112 coating contains a surfactant, which has a polyether group and a urethane linking group, so as to improve the sensitivity. CN200780006645.4 discloses a method for making a positive thermal plate, which contains an anti-fouling agent in the coating or the developing solution. The anti-fouling agent is a 5-membered aromatic heterocyclic compound containing a -NH- group, which is a substituted benzotriazole, 1,2,3-triazole, tetrazole or indazole compound. In this way, the formation of sludge is inhibited or reduced.

[0004] Generally, the principle of thermal imaging is to use the principle of light-heat conversion, that is, when the plate is exposed to scanning by infrared laser (830 nm), the infrared absorbing dye in the scanning part absorbs light and converts it into heat energy, so that the exposed area and the non-exposed area form a dissolution contrast. The exposed area is decomposed and releases alkali-soluble groups-carboxyl or phenolic hydroxyl under the action of the generated proton acid, which has alkali solubility and is dissolved during development, exposing the hydrophilic plate base to become a hydrophilic blank part; the thermal coating in the non-exposed area does not have a decomposition reaction and does not have alkali solubility, and remains on the plate after development to become an oleophilic image part.

[0005] For image resolution, the thermal plate is usually colored with triarylmethane dye, the conventional coloring dye has strong binding force with alkali-soluble resin and aluminum base, the photosensitive composition needs to use strong exposure energy or adopt strong developing condition to reach the target photosensitivity, so that the thermal plate formed has low photosensitivity, or poor resistance to alkali developer, insufficient protection to the screen dots, low residual film rate in the developing process, which not only affects the image reproducibility, but also increases the development sludge residue. SUMMARY

[0006] To solve the above problems, the application provides a modified coloring dye, a preparation method and application thereof, and a photosensitive composition added with the modified coloring dye, the thermal plate of the composition has the advantages of high photosensitivity, mild developing condition and less developing sludge.

[0007] The purpose of the application is achieved in the following manner: a modified coloring dye, the structure of the modified coloring dye is any of the following formulae:

[0008]

[0009] Formula I

[0010]

[0011] Formula II

[0012]

[0013] Formula III

[0014]

[0015] Formula IV

[0016] In the above structure, R represents H or NH2 or OH.

[0017] So far, the imaging mechanism of the thermal plate can be explained by hydrogen bond, which is a weak interaction between a hydrogen atom with electron deficiency and an electron-rich atom or group, and is an interaction force between a permanent dipole, which is similar to van der Waals force. Generally, hydrogen bond can be represented as "X-H...Y", wherein X and Y are generally elements with high electronegativity, such as N, O, F, etc. Hydrogen bond can be intermolecular or intramolecular. The composition of the application contains modified coloring dye, which contains naphthalene sulfonic acid group in the structure, and can form hydrogen bond with oxygen atom in the photosensitive composition compared with conventional coloring dye. On the other hand, the modified coloring dye has large molecular weight and small binding force with aluminum base, and has the characteristics of high photosensitivity and mild developing condition, so as to effectively improve the screen dot quality of the plate material, which is conducive to ensuring the image reproduction and precision, and at the same time, the sludge residue after development is greatly reduced due to the mild developing condition.

[0018] The preparation method of the modified color dye adds 2-naphthalenesulfonic acid, 8-amino-2-naphthalenesulfonic acid or 5-amino-1-naphthalenesulfonic acid, solvent DMF, stirs and dissolves, after the dissolution is completed, adds NaH, warms up to 55-65℃, keeps warm for 0.8-2 hours, adds ethyl violet, methyl violet, stirs and reacts for 4-8 hours; cools down to below 30℃; in a dispersion kettle, adds deionized water, 36.5% mass concentration of concentrated hydrochloric acid, stirs uniformly, slowly drips the above-mentioned reaction liquid, dries in a centrifuge, deionized water leaches, immerses and washes, the effluent is neutralized, dries at a temperature below 80℃, and the modified color dye is obtained.

[0019] The application of the modified color dye can be as follows:

[0020] The application to a positive thermal sensitive photo composition as a modified color dye: a positive thermal sensitive photo composition, including alkali-soluble resin, dissolution inhibitor, development promoter, color dye and infrared absorption dye. The color dye is at least one modified color dye of formula I, formula II, formula III, formula IV or is combined with a conventional color dye.

[0021] The conventional color dye has oil yellow #10 1, oil yellow #103, oil pink #312, oil green BG, oil blue BOS, oil blue #603, oil black, oil black BS, oil black T-505, victoria pure blue BO, alkali blue fluorostannate. Especially including ethyl violet, methyl violet, crystal violet, malachite green, bright green, victoria blue B, victoria blue R, victoria blue 130, victoria pure blue, methylene blue (CI52015) and the like.

[0022] The color dye accounts for 1-5% of the total weight of the photo composition, preferably 2-3.5%.

[0023] The alkali-soluble resin is phenolic resin or poly-p-hydroxystyrene resin, and the amount accounts for 50-90% of the total weight of the photo composition, preferably 60-85%.

[0024] Further, the phenol resin is at least one of m-cresol-p-cresol phenol resin, phenol-p-cresol phenol resin, o-cresol-p-cresol phenol resin, and phenol resin. The phenol resin can be selected from m-cresol phenol resin (Mw 4000-8000, Mw / Mn 4-8), m-cresol-p-cresol phenol resin (molar ratio of m-cresol and p-cresol 8:2-6:4, Mw 4000-10000, Mw / Mn 4-12), phenol-p-cresol phenol resin (molar ratio of phenol and p-cresol 5:5-3:7, Mw 4000-6000, Mw / Mn 4-6), phenol-o-cresol-p-cresol phenol resin (molar ratio of phenol, o-cresol, and p-cresol 2:1:7, Mw 6000-9000, Mw / Mn 6-9), phenol-m-cresol-p-cresol phenol resin (molar ratio of phenol, m-cresol, and p-cresol 1:6:4, Mw 7000-10000, Mw / Mn 7-10), and modified phenol resin (Mw 12000-13500, Mw / Mn 8-11), and the like. The linear phenol resin of the present application preferably has a weight average molecular weight of 1000-100000, more preferably 2000-50000, and most preferably 2500-14000.

[0025] Further, the dissolution inhibitor is a quaternary ammonium salt nitrogen-containing compound, an imidazole compound, a quinolinium salt compound, a benzothiazolium salt compound, an aromatic carboxylic acid ester, a lactone ketone, an aromatic disulfone, a polyalkoxy ether, particularly a polyethylene glycol, and the like. The dissolution inhibitor is present in an amount of 5-30% by weight, preferably 10-15% by weight, of the total weight of the photosensitive composition.

[0026] The development accelerator is at least one of an organic acid, an acid anhydride, a phenol, or a sulfone. Examples of the development accelerator include sulfonic acid, phosphoric acid, alkylbenzenesulfonic acid, benzoic acid, adipic acid, lauric acid, ascorbic acid, acetic anhydride, phthalic anhydride, maleic anhydride, chloromaleic anhydride, succinic anhydride, bisphenol A, p-nitrophenol, p-ethoxyphenol, 2,3,4-trihydroxybenzophenone, 4-hydroxybenzophenone, and the like. The development accelerator is present in an amount of 0.1-10% by weight of the total weight of the photosensitive composition.

[0027] The photosensitive composition further comprises a photo-thermal conversion substance infrared absorption dye, i.e. an infrared absorption dye having an absorption peak at 790-830 nm, and the infrared absorption dye is a phycobilin infrared absorption dye. Generally, commercially available phycobilin infrared absorption dyes at home and abroad are selected, such as LC-01 of Honywell Company, NK-2014, NK-2268, HCD-21 of Linyuan Company, PS-101, PS-102 of Japan Chemicals, S 0094 of FEW CHEMICALS Company, and NIRD of Liaoning Huahai Blue Sail, etc. The present application mainly selects 830 nm infrared sensitizing dye of Wenzhen Chemical Industry. The absorption peak wavelength of these infrared absorption dyes is generally 810-830 nm, and the absorption peak measured in ethanol solvent is 815-820 nm, and the absorption peak in the thermal CTP coating liquid is generally about 815 nm. The amount is 1-5% of the total weight of the photosensitive composition, preferably 2.5-3.5%.

[0028] The photosensitive composition is prepared into a positive thermal CTP coating liquid with a solid content of 7-20%.

[0029] The solvent system selected for the photosensitive composition prepared into a thermal CTP coating liquid has good solubility to the above components, moderate evaporation speed and a boiling point of 70-150°C, and the boiling point of the main solvent is preferably 100-140°C. The solvent that can be selected includes at least one of ethylene glycol monoethyl ether, ethylene glycol monomethyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, cyclohexanone, butanone, ethylene glycol monoethyl ether acetate, propylene glycol ethyl ether acetate, γ-butyrolactone, dioxane, etc. The amount of the solvent is determined according to the viscosity of the coating liquid required by the coating machine, and generally, the solid content of the photosensitive composition solution is between 10-15%, and the viscosity is between 3-5 mm 2 ·s -1 . The coating liquid viscosity required by some high-speed production lines is lower than 3 mm 2 ·s -1 , so the solid content is also lower than 10%.

[0030] When the thermal CTP coating liquid is prepared, the several components should be dissolved in the following order, generally, the infrared dye which is difficult to dissolve is dissolved first, then the film-forming resin, the dissolution inhibitor and the developing promoter are added after the infrared dye is completely dissolved, and finally the coloring dye is added.

[0031] The alkaline developing solution is an alkaline solution mainly composed of a developing agent, a protective agent, a wetting agent and the like. The developing agent used in the present application is mainly composed of an alkaline aqueous solution. The developing agent is used to dissolve the exposed photosensitive layer of the positive CTP plate, and a strong alkaline substance can be used, which can be selected from sodium hydroxide, potassium hydroxide, sodium carbonate, potassium carbonate, sodium silicate, potassium silicate, disodium hydrogen phosphate or trisodium phosphate. The concentration of the strong alkaline substance is preferably 0.5-30% (wt). The protective agent and the wetting agent in the developing solution are anionic surfactants or non-ionic surfactants.

[0032] Compared with the prior art, the modified color dye provided by the present application contains a naphthalene sulfonic acid group in the structure, can form a hydrogen bond with the oxygen atom of the photosensitive composition, has a large molecular weight and a small binding force with aluminum, leaves no residual color in the blank area after development, has a high photosensitivity and a mild development condition, thereby effectively improving the dot quality of the plate material, is beneficial to guarantee the image reproduction and precision, and simultaneously reduces a large amount of sludge residue after development due to the mild development condition. DETAILED DESCRIPTION

[0033] Hereinafter, the present application will be described in detail with reference to specific examples. It is necessary to point out that the examples are only used to further illustrate the present application and cannot be understood as a limitation on the protection scope of the present application. Those skilled in the art can make some non-essential improvements and adjustments according to the content of the present application.

[0034] The following are specific examples of the present application, but the content of the present application is not limited thereto. In the examples, the naphthalene sulfonic acid and derivatives are from Beijing Bailingwei Technology Co., Ltd.; N, N-dimethylformamide (DMF) is from Union Carbide Chemical; sodium hydride is from Shanghai Langrui Fine Chemicals Co., Ltd.; concentrated hydrochloric acid is from Kaifeng Chemical Reagent Factory. Methyl violet and ethyl violet are from Shenyang Jinsitong.

[0035] Example 1

[0036] Preparation of a thermal plate

[0037] (1) Preparation of an aluminum plate base:

[0038] An aluminum plate with a thickness of 0.28 mm is subjected to degreasing treatment in a 7wt% sodium hydroxide aqueous solution at a temperature of 55°C for 40 seconds, and is subjected to electrolytic treatment in a concentrated hydrochloric acid aqueous solution with a concentration of 10wt% at a temperature of 25°C by using a sinusoidal wave alternating current, 50Hz alternating current, and a current of 50A / dm 2, electrolysis time 60 seconds, control Ra = 0.3-0.6um, preferably 0.4~0.6μm. Then at 60℃ temperature, in 50wt% concentration of sodium hydroxide aqueous solution deslagging treatment 10 seconds, and then at 25℃ temperature, current density is 5A / d㎡, concentration of 20wt% sulfuric acid solution treatment 40 seconds, control oxide film = 2.5-3.5g / m 2 . Finally, at 65℃ using NaH2PO4-NaF solution for sealing hole treatment 20 seconds, that is, the aluminum base suitable for thermal sensitive plate.

[0039] (2) coating:

[0040] The photosensitive composition is prepared into a thermal CTP coating liquid with a solid content of 10%, the aluminum base prepared by the above method is fixed to an inclined photosensitive coating machine (TH980 type inclined photosensitive coating drying machine), the coating liquid is poured onto the aluminum base by centrifugal coating method, and the photosensitive layer is dried at 130℃ for 2 minutes, and the film thickness of the photosensitive layer is 1.5g / m 2 .

[0041] Positive thermal sensitive plate test method

[0042] (1) Plate photosensitivity detection method:

[0043] On the SCREEN8600M2 plate making machine, use the self-test strip, imaging and screening 175lpi, output resolution 2400dpi, according to the following exposure conditions (see Table I) and development conditions (see Table II), different laser energy scanning plate making on the sample plate, and then determine the photosensitivity by the following method.

[0044] Use X-rite's dot measuring instrument IC-Plate2 to measure 50% flat dot value under different exposure energy, until the display value of the flat dot area in the range of 49.5%-50.5% is found, and the energy here is the photosensitivity of the plate, the larger the value, the lower the photosensitivity, and the smaller the value, the higher the photosensitivity. Record the photosensitivity of the plate and the corresponding 3% dot.

[0045] Use 80-100 times optical magnifying glass to observe the number of small dots restored at 1:1, and the number of points observed is the number of small dots, and the more the number of small dots restored, the higher the imaging accuracy of the plate.

[0046] Table I

[0047]

[0048] Table II

[0049]

[0050] (2) Clean dot detection:

[0051] The density of the 0% dot corresponding to different energy of the test pattern is measured by X-rite 500 type spectrodensitometer, then a drop of acetone is added at the 0% dot, after the acetone is volatilized, the density of the area where the drop of acetone passes is measured by the densitometer from the lowest energy, if the density before and after is the same, the exposure energy of the corresponding pattern is the clean point of the pattern.

[0052] (3) Muddy residue detection after development:

[0053] After the plate material is exposed by the SCREEN 8600M2 plate making machine with 75% exposure energy, the coating of 0.15 m2 exposed area is washed away by TPD-85 developing solution at room temperature, the developing solution is filtered by a Ф15 cm medium-speed quantitative filter paper, and then dried and weighed, which is the weight of the muddy residue.

[0054] The photosensitive composition is as shown in Table Three:

[0055] Table Three

[0056]

[0057] The synthesis method of BG1 in the table is as follows: 200 g of 2-naphthalenesulfonic acid, 1200 ml of DMF are added into a 5L reaction kettle, stirred and dissolved, after the dissolution is completed, 48 g of NaH is added, heated to 60°C for 1 hour, 492 g of ethyl violet is added, and stirred for 5 hours of reaction; cool down and stand overnight. In a 10L dispersion kettle, 6L of deionized water and 400ml of concentrated hydrochloric acid are added and stirred uniformly, then the above reaction liquid is slowly dropped into the kettle, centrifuged, washed with deionized water, and the effluent is neutralized, and dried at 80°C to obtain 650 g of green powdery solid. Compound BG1 is obtained.

[0058] Example 2

[0059] The sample preparation method is the same as that in Example 1

[0060] The photosensitive composition is as shown in Table Four:

[0061] Table Four

[0062]

[0063] The synthesis method of BG2 in the table is as follows: 220 g of 8-amino-2-naphthalenesulfonic acid, 1200 ml of DMF are added into a 5L reaction kettle, stirred and dissolved, after the dissolution is completed, 48 g of NaH is added, heated to 60°C for 1 hour, 408 g of methyl violet is added, and stirred for 5 hours of reaction; cool down and stand overnight. In a 10L dispersion kettle, 6L of deionized water and 400ml of concentrated hydrochloric acid are added and stirred uniformly, then the above reaction liquid is slowly dropped into the kettle, centrifuged, washed with deionized water, and the effluent is neutralized, and dried at 80°C to obtain 585 g of green powdery solid. Compound BG2 is obtained.

[0064] Example 3

[0065] The sample preparation method is the same as Example 1

[0066] The photosensitive composition is as shown in Table 5:

[0067] Table 5

[0068]

[0069] The synthesis method of BG3 in the table is as follows: 220 g of 5-amino-1-naphthalenesulfonic acid, 1200 ml of DMF were added into a 5 L reaction kettle, and stirred and dissolved. After completion of dissolution, 48 g of NaH was added, and the temperature was raised to 60°C for 1 hour. Then, 492 g of ethyl violet was added, and stirred for 5 hours. After cooling, it was left overnight. In a 10 L dispersion kettle, 6 L of deionized water and 400 ml of concentrated hydrochloric acid were added and stirred uniformly. The above reaction liquid was slowly dropped into the kettle, and centrifuged to dryness. The eluate was washed and immersed with deionized water until it became neutral. Then, it was dried at 80°C to obtain 670 g of green powder solid. Compound BG3 was obtained.

[0070] Example 4

[0071] The sample preparation method is the same as Example 1

[0072] The photosensitive composition is as shown in Table 6:

[0073] Table 6

[0074]

[0075] The synthesis method of BG2 in the table is as follows: the synthesis method is the same as Example 2

[0076] Example 5

[0077] The sample preparation method is the same as Example 1

[0078] The photosensitive composition is as shown in Table 7:

[0079] Table 7

[0080]

[0081] The synthesis method of BG3 in the table is as follows: the synthesis method is the same as Example 3

[0082] Comparative Example 1

[0083] The sample preparation method is the same as Example 1

[0084] The photosensitive composition is as shown in Table 8:

[0085] Table 8

[0086]

[0087] Comparative Example 2

[0088] The sample was prepared in the same manner as in Example 1

[0089] The photosensitive composition was as shown in Table 9:

[0090] Table 9

[0091]

[0092] The plate material imaging performance was investigated by installing the photosensitive lithographic plate on a plate making machine and exposing it. The plate was developed with an alkaline developer TPD-85 (manufactured by Lucky Huaguang Printing Technology Co., Ltd.) at 25°C for 20 seconds, and the photosensitivity, dot performance and sludge residue of the plate material were detected.

[0093] The plate material performance is shown in Table 10.

[0094] Table 10: Performance of photosensitive imaging and plate making of Examples 1-5

[0095]

[0096] From the above results, it can be seen that the conventional coloring dye has a greater impact on the sensitivity and sludge residue. By using the basic composition of the present application, a positive thermal plate material with high sensitivity, mild developing conditions and less sludge residue is obtained under different plate making conditions.

[0097] The above described is only the preferred embodiment of the present application, but the protection scope of the present application is not limited thereto, it should be pointed out that for those skilled in the art and any person skilled in the art, under the premise of not departing from the overall concept of the present application, according to the technical scheme and the inventive concept of the present application, equivalent replacement or change is made, and several changes and improvements are made, which should also be regarded as the protection scope of the present application.

Claims

1. A positive-image thermally sensitive light composition, characterized in that: This includes modified coloring dyes, whose structures are any of the following formulas: Formula I Formula II Formula III Formula IV In the above structural formula, R represents H, NH2, or OH.

2. The positive thermal-sensitive light composition according to claim 1, characterized in that: The modified coloring dye is prepared by adding 2-naphthalenesulfonic acid, 8-amino-2-naphthalenesulfonic acid, or 5-amino-1-naphthalenesulfonic acid and DMF solvent to a reaction vessel and stirring to dissolve. After dissolution, NaH is added, and the temperature is raised to 55-65℃ and kept at that temperature for 0.8-2 hours. Ethyl violet and methyl violet are added, and the reaction is carried out with stirring for 4-8 hours. The mixture is then cooled to below 30℃. In a dispersion vessel, deionized water and 36.5% concentrated hydrochloric acid are added and stirred until homogeneous. The above reaction solution is then slowly added dropwise and centrifuged to dry. The effluent from rinsing and soaking with deionized water is neutral and then dried at a temperature below 80℃ to obtain the modified coloring dye.

3. The positive thermal-sensitive light composition according to claim 1, characterized in that: It includes alkali-soluble resins, dissolution inhibitors, development promoters, coloring dyes, and infrared absorbing dyes, wherein the coloring dyes include the modified coloring dyes mentioned above.

4. The positive thermal-sensitive light composition according to claim 3, characterized in that: The coloring dye comprises at least one modified coloring dye and a conventional coloring dye, wherein the conventional coloring dye is at least one of oil yellow, oil pink, oil green, oil blue, oil black, oil-soluble blue, basic brilliant blue, Victoria blue, phthalocyanine blue, malachite green, dark green, phthalocyanine green, crystal violet, methyl violet, ethyl violet, dimethyl yellow, or fluorescent yellow.

5. The positive thermally sensitive light composition according to claim 3, characterized in that: The amount of alkali-soluble resin accounts for 50-90% of the total weight of the photosensitive composition; the amount of dissolution inhibitor accounts for 5-30% of the total weight of the photosensitive composition; the amount of development promoter accounts for 0.1%-10% of the total weight of the photosensitive composition; the amount of infrared absorbing dye accounts for 1-5% of the total weight of the photosensitive composition; and the amount of coloring dye accounts for 1-5% of the total weight of the photosensitive composition.

6. The positive thermally sensitive light composition according to claim 5, characterized in that: The amount of alkali-soluble resin accounts for 60-85% of the total weight of the photosensitive composition; the amount of dissolution inhibitor accounts for 10-15% of the total weight of the photosensitive composition; the amount of development promoter accounts for 0.1%-10% of the total weight of the photosensitive composition; the amount of infrared absorbing dye accounts for 2.5-3.5% of the total weight of the photosensitive composition; and the amount of coloring dye accounts for 2-3.5% of the total weight of the photosensitive composition.

7. The positive thermosensitive light composition according to claim 3, characterized in that: The alkali-soluble resin is a phenolic resin or a poly(p-hydroxystyrene) resin; the developing accelerator is at least one of an organic acid, anhydride, phenol, or sulfone; and the infrared absorbing dye is a cyanin-based infrared absorbing dye.

8. The use of the photosensitive composition according to any one of claims 1-7 in positive thermal CTP plates.

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