A hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin and a chemical-resistant thermal sensitive plate

Abstract

The present invention provides a hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin and a chemical-resistant thermal printing plate. The polyvinyl alcohol derivative is a product obtained by an urethanation reaction of polyvinyl alcohol and isocyanate acrylate; the molecular structural unit of the polyacrylic acid resin contains at least a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: an acrylic acid copolymerization unit containing an alkali-soluble group; the hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin has excellent chemical resistance, the chemical-resistant thermal printing plate contains the hybrid polymer, and the imaging layer has excellent chemical resistance, so the imaging quality and printing resistance of the thermal printing plate are significantly improved.

Description

Technical Field

[0001] The present invention belongs to the technical field of lithographic printing, and particularly relates to a hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin and a chemical-resistant thermal plate. Background Art

[0002] Computer to plate (CTP) began in the 1980s. Currently, CTP technology is widely used in the modern printing field. Common CTP plates are divided into photosensitive CTP plates (referred to as photosensitive plates for short) and thermal CTP plates (referred to as thermal plates for short) according to the imaging laser source.

[0003] The thermal plate is an offset printing plate material that uses infrared laser for imaging. The thermal plate is widely used because it can be operated in a light room and has high imaging quality. The positive thermal plate making technology is currently the most mature, stable and effective plate making technology. With the increasingly strict environmental protection requirements in various countries, since UV ink does not contain volatile solvents, in order to reduce air environmental pollution, UV ink is widely used in the printing field. However, since UV ink contains monomers that can be UV-cured, it will erode the imaging layer of traditional thermal plates during the printing process, and the imaging layer will be swollen or partially dissolved, resulting in dot gain and blurring, and a sharp drop in the printing resistance. Therefore, improving the chemical resistance of the plate material and the printing resistance is the key point in the development of thermal plates at present.

[0004] One of the most important methods to improve the chemical properties of thermal plates is the development of the thermal layer composition of the plate material and functional resins. Eastman Kodak disclosed in CN101321632A that the chemical resistance of the plate material is improved by introducing phosphoric acid side groups or adamantane side groups into the polymer; Agfa announced in WO2004035686 a polymer containing N-pyrazole groups to increase the chemical resistance of the printing plate; Fujifilm disclosed in CN201380011228.4 a method to increase the chemical resistance and printing resistance of the printing plate by using polyvinyl acetal resin. Summary of the Invention

[0005] To solve the above problems, the present invention provides a hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin and a chemical-resistant thermal plate. The hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin has excellent chemical resistance. The chemical-resistant thermal plate contains the hybrid polymer, and the imaging layer has excellent chemical resistance. Therefore, the imaging quality and printing resistance of the thermal plate are significantly improved.

[0006] The object of the present invention is achieved in the following manner: A hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin, where the polyvinyl alcohol derivative is a product obtained by urethanization reaction of polyvinyl alcohol and isocyanate acrylate; the molecular structural units of the polyacrylic acid resin contain at least a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: an acrylic copolymer unit containing an alkali-soluble group; the hybridization method of the polyvinyl alcohol derivative and the polyacrylic acid resin is: first synthesize the polyacrylic acid resin, and add the polyvinyl alcohol derivative in the later stage of the reaction for synthesizing the polyacrylic acid resin for hybridization to obtain a hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin. That is, first synthesize the polyacrylic acid resin, and in the later stage of the reaction for synthesizing the polyacrylic acid resin, when the reaction has not terminated, add the polyvinyl alcohol derivative to continue the double bond polymerization reaction, similar to the block reaction of polymers.

[0007] Meanwhile, according to the characteristics of the hybrid polymer, a thermal plate with a supramolecular hydrogen bond association mechanism was designed and developed. The plate material contains this hybrid polymer, especially a thermal plate containing a special sensitizer at the same time, and the thermal plate has excellent chemical resistance.

[0008] First, describe the hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin:

[0009] A hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin: The polyvinyl alcohol derivative is a product obtained by urethanization reaction of polyvinyl alcohol and isocyanate acrylate; the polyacrylic acid resin is a polymer whose molecular structural units contain at least a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: an acrylic copolymer unit containing an alkali-soluble group; the hybridization method of the polyvinyl alcohol derivative and the polyacrylic acid resin is: first synthesize the polyacrylic acid resin, and hybridize with the polyvinyl alcohol derivative during the synthesis process to form a hybrid polymer.

[0010] Among them, the polyvinyl alcohol derivative is a product obtained by urethanization reaction of the hydroxyl group in polyvinyl alcohol and the isocyanate group in isocyanate acrylate. Currently, isocyanate acrylate is a brand-new functional monomer in the world, and its basic structure is as follows:

[0011]

[0012] R 1 is a hydrogen atom or a methyl group, R 2 is an ester group, an aryl group, or a covalent bond, etc., and r is an integer from 1 to 3.

[0013] It contains both an isocyanate group and a double bond. Currently, only two isocyanate acrylates, ethyl isocyanate acrylate (abbreviation: AOI, CAS: 13641-96-8) and ethyl isocyanate methacrylate (abbreviation: MOI, CAS: 30674-80-7), have been successfully developed and industrialized in the world.

[0014] Next, polyacrylic resin is described. The polyacrylic resin is a copolymer unit whose molecular structural unit contains at least a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: an acrylic copolymer unit containing an alkali-soluble group. The polyacrylic resin preferably used in the present invention is a ternary free radical copolymer of copolymer units a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: acrylic acid or methacrylic acid. Among them: in the polyacrylic resin, by percentage, the weight ratio of monomer a p-hydroxystyrene is 10-70%, the weight ratio of monomer b acrylamide is 10-70%, and the weight ratio of monomer c acrylic acid or methacrylic acid is 10-30%.

[0015] One of the copolymer components of polyacrylic resin: p-hydroxystyrene, which contains a rigid benzene ring structure that can provide chemical resistance. The hydrogen bonds at the meta position and the para hydroxyl group hydrogen bonds on the benzene ring and the alkali-soluble resin together form supramolecular hydrogen bond association; after the laser thermal action releases the association, phenolic hydroxyl groups are released, and the phenolic hydroxyl groups are developed with alkali to achieve imaging; at the same time, the resin contains the same phenolic hydroxyl group structure as the alkali-soluble resin, improving the compatibility of the two resins, being more conducive to intermolecular hydrogen bond association, and improving the solvent resistance of the plate.

[0016] One of the copolymer components of polyacrylic resin: acrylamide or methacrylamide is a strongly polar monomer, which can endow the polymer resin with excellent chemical resistance, improve the chemical resistance of the thermal sensitive layer, and improve the printing resistance of the plate.

[0017] One of the copolymer components of polyacrylic resin: acrylic acid or methacrylic acid. The alkali-soluble group provides image imaging during alkali development of the plate. Common acrylic monomers with alkali-soluble groups include acrylic monomers containing carboxyl groups, sulfonic acid groups, phosphoric acid groups, amino groups, phenolic hydroxyl groups, etc. The alkali-soluble group is preferably a carboxyl group, and carboxylic acid acrylic monomers have the advantage of high cost performance.

[0018] The hybridization method of polyvinyl alcohol derivative and polyacrylic resin is: first synthesize a ternary copolymer, and hybridize with the polyvinyl alcohol derivative during the synthesis process to form a hybrid polymer.

[0019] A chemical-resistant thermal sensitive plate, the thermal sensitive plate includes a hydrophilic carrier and a thermal sensitive layer, wherein the thermal sensitive layer contains a hybrid polymer of phenolic resin, polyvinyl alcohol derivative and polyacrylic resin.

[0020] The thermal sensitive layer further contains a sensitizer.

[0021] The thermal sensitive layer further contains an infrared absorption dye and a background dye.

[0022] In the thermosensitive layer, calculated by weight percentage, the phenolic resin accounts for 40 - 80% of the total solids of the composition, the hybrid polymer of polyvinyl alcohol derivative and polyacrylic resin accounts for 10 - 50% of the total solids of the composition, the sensitizer accounts for 1 - 10% of the total solids of the composition, the infrared absorption dye accounts for 1 - 5% of the total solids of the composition, and the background dye accounts for 1 - 5% of the total solids of the composition.

[0023] The phenolic resin is at least one of m-cresol novolac resin, m-cresol-p-cresol novolac resin, phenol-p-cresol novolac resin, o-cresol-p-cresol novolac resin, phenol-o-cresol-p-cresol novolac resin, phenol-m-cresol-p-cresol novolac resin, and polyurethane-modified linear phenolic resin; the phenolic resin is m-cresol novolac resin (Mw is between 4000 - 8000, Mw / Mn is between 4 - 8), m-cresol-p-cresol novolac resin (the molar ratio of m-cresol to p-cresol is 3:2 to 4:1, Mw is between 4000 - 10000, Mw / Mn is 4 - 12), phenol-p-cresol novolac resin (the molar ratio of phenol to p-cresol is 5:5 to 3:7, Mw is between 4000 - 6000, Mw / Mn is 4 - 6), o-cresol-p-cresol novolac resin, phenol-o-cresol-p-cresol novolac resin (the molar ratio of phenol, o-cresol and p-cresol is 2:1:7, Mw is between 6000 - 9000, Mw / Mn is 6 - 9), phenol-m-cresol-p-cresol novolac resin (the molar ratio of phenol, m-cresol and p-cresol is 1:6:4, Mw is between 7000 - 10000, Mw / Mn is 7 - 10), and polyurethane-modified linear phenolic resin (Mw is between 12000 - 13500, Mw / Mn is 8 - 11; poly(p-hydroxystyrene) selects a product with Mw between 5000 - 30000 and Mw / Mn between 1.1 - 1.3. The phenolic resin accounts for 30 - 90% of the total solids of the composition, preferably 40 - 80%.

[0024] The infrared absorption dye is a cyanine dye with an absorption peak at 750 - 850 nm.

[0025] The background dye is any one of oil-soluble blue, basic brilliant blue, victoria pure blue, phthalocyanine blue, malachite green, dark green, phthalocyanine green, crystal violet, methyl violet, ethyl violet, dimethyl yellow, and fluorescent yellow.

[0026] In order to improve the imaging performance of the thermal-sensitive plate, a sensitizer is contained in the thermal-sensitive layer of the present invention. A good sensitizer has the functions of hydrogen bond association, laser thermal decomposition development imaging, and anti-solvent. The sensitizer is 5-ethyl-5-phenyl-1-methyl-2,4,6-(1H,3H,5H)-pyrimidinetrione (abbreviation: phenobarbital). It contains an aromatic ring structure, and has good compatibility with phenolic resin and hybrid resin which also have aromatic ring structures, avoiding the transfer of small molecules and improving the chemical resistance of the thermal-sensitive plate.

[0027] The infrared absorption dye component in the thermal-sensitive layer is described in detail below: The infrared absorption dye mainly functions to more effectively convert the laser infrared light into heat energy to achieve thermal imaging. The maximum absorption wavelength range of the infrared absorption dye is 750 - 1100 nm, and it is selected from carbon black, azo dyes, triarylamine dyes, indolium dyes, oxacarbocyanine dyes, cyanine dyes, phthalocyanine dyes, indocyanine dyes, phthalocyanine dyes, polythiophene dyes, pyrazoline azo dyes, oxazine dyes, naphthoquinone dyes, anthraquinone dyes, quinoneimine dyes, methylene dyes, porphyrin dyes, etc. The present invention preferably uses cyanine dyes with a wavelength of 750 - 850 nm, and the infrared absorption dye accounts for 1% - 5% of the total solid content of the thermal-sensitive layer composition.

[0028] The background dye in the thermal-sensitive layer is described in detail below: The background dye functions to color the coating layer, in order to increase the image density after plate-making of the thermal-sensitive plate, facilitating visual inspection of the thermal-sensitive plate after plate-making or measurement of the plate properties by an image analysis and measurement device. The background dye is any one of oil-soluble blue, basic brilliant blue, victoria pure blue, phthalocyanine blue, malachite green, dark green, phthalocyanine green, crystal violet, methyl violet, ethyl violet, dimethyl yellow, and fluorescent yellow, and the background dye accounts for 1% - 5% of the total solid content of the thermal-sensitive layer composition.

[0029] Finally, the hydrophilic carrier of the thermal plate of the present invention will be described in detail: The thermal plate composition of the present invention needs to be coated on the hydrophilic carrier of the thermal plate. The carrier of the thermal plate includes metal plate bases such as copper plate bases, aluminum plate bases, and so on. The selected hydrophilic carrier of the present invention is an aluminum plate base after electrolytic roughening, anodic oxidation, and sealing treatment, with an average roughness of the center line of 0.3 - 0.6 um, which is obtained by electrolytic roughening. The aluminum plate base contains more than 99% aluminum, 0.1% - 0.5% iron, 0.03% - 0.3% silicon, 0.003% - 0.03% copper, and 0.01% - 0.l% titanium. The electrolytic roughening electrolyte can be an aqueous solution of acid, alkali, or salt. First, place the aluminum plate in an aqueous solution of 1% - 30% sodium hydroxide, potassium hydroxide, sodium carbonate, sodium silicate, etc., and chemically corrode it at a temperature of 20 - 80°C for 5 - 250 seconds. Then neutralize it in 10% - 30% nitric acid or sulfuric acid at a temperature of 20 - 70°C to remove the ash. At a temperature of 10 - 60°C, use rectangular waves, trapezoidal waves, sine waves, etc. with alternating positive and negative polarities, and electrolytically process it in a nitric acid or hydrochloric acid electrolyte at a current density of 5 - 100 A / dm2 for 10 - 300 seconds. Then perform anodic oxidation treatment. Anodic oxidation is usually carried out by the sulfuric acid method. The concentration of sulfuric acid used is 5 - 30%, the current density is 1 - 15 A / dm2, the oxidation temperature is 20 - 60°C, and the oxidation time is 5 - 250 seconds to form an oxide film of 1 - 10 g / m2. Finally, perform sealing treatment with an aqueous solution of sodium silicate.

[0030] When producing the thermal layer of the present invention, some other necessary additives can also be added, such as solvents, surfactants, and so on. The solvent is mainly used to prepare the thermal layer into a coating solution, including: alcohols, ketones, esters, ethers, amides, aromatic solvents, and dichloroethylene, tetrahydrofuran, etc. The solvent can be used in pure form or in a mixture; for surfactants, non-ionic surfactants, amphoteric surfactants, silicone-containing surfactants, fluorine-containing surfactants, etc. can be selected, such as betaines, stearic acid glycerol esters, sorbic acid palm oil esters, polysiloxanes, polyfluoroalkyl ethers.

[0031] The thermal layer of the present invention is usually coated by known techniques in the art such as knife coating, doctor blade coating, bar coating, roll coating, press coating, etc.

[0032] Compared with the prior art, the copolymerization components of the hybrid polymer of the present invention: p-hydroxystyrene, which contains a rigid benzene ring structure that can provide chemical resistance. The hydrogen bonds at the meta position and the hydrogen bonds of the para hydroxyl group on the benzene ring and phenolic resin together form supramolecular hydrogen bond association; acrylamide can endow the polymer resin with excellent chemical resistance, and the acrylic acid monomer contains an alkali-soluble group, providing good alkali-developable imaging performance. The hybrid polymer contains urethane bonds that have an anti-wear effect. The urethane bonds contain strong polar hydrogen bonds that can form supramolecular hydrogen bond association with the phenolic hydroxyl groups in the alkali-soluble resin; the end of the side chain of this copolymerization component also contains diphenyl, which has good rigidity and chemical resistance.

[0033] In the provided chemical-resistant thermal-sensitive plate, the phenolic hydroxyl groups in the hybrid polymer and the phenolic resin can form associations with hydrogen bonds. Both the hydrogen atoms on the benzene ring and the phenolic hydroxyl groups in the solvent-resistant resin and the phenolic resin contain hydrogen bonds, and the molecules form an alkali dissolution-resistant structure by associating with each other through hydrogen bonds. This association is more complete and thorough under laser thermal dissociation in the presence of a sensitizer. The special sensitizer contains an aromatic ring structure, which has good compatibility with the phenolic resin and the hybrid resin that also have aromatic ring structures, avoiding the transfer of small molecules and improving the chemical resistance of the thermal-sensitive plate. Specific embodiments

[0034] The following are the synthesis examples of the present invention, but the present invention is not limited to the following examples. The following synthesis examples are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments based on the above content of the present invention.

[0035] Raw materials and their codes, obtaining companies: p-hydroxystyrene (PHS): Hubei Jusheng Technology; acrylonitrile (AN): Tianjin Fengchuan Chemical Reagent; ethyl acrylate isocyanate (AOI) and ethyl methacrylate isocyanate (MOI): Showa Denko K.K., Japan; polyvinyl alcohol PVA550, PVA500: from Kuraray, Japan; azobisisobutyronitrile (AIBN): Tianjin Fuchen Chemical Reagent; dibutyltin dilaurate: Tianjin No. 2 Chemical Reagent Factory; dimethyl sulfoxide DMSO and dimethylformamide (DMF): Shanghai Union Carbide Chemical.

[0036] The basic synthesis method is as follows:

[0037] First, synthesize the intermediate polyvinyl alcohol derivative for standby:

[0038] Synthesis of polyvinyl alcohol derivative M1: Add 100 g of PVA550, 20 g of ethyl acrylate isocyanate (AOI), 1 g of dibutyltin dilaurate, 400 g of dimethyl sulfoxide into a 500 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux and nitrogen protection device, and stir and react at 70 °C for 3 hours to end. The intermediate M1 is for standby;

[0039] Synthesis of polyvinyl alcohol derivative M2: Add 100 g of PVA500, 20 g of ethyl methacrylate isocyanate (MOI), 1 g of dibutyltin dilaurate, 400 g of dimethyl sulfoxide into a 500 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux and nitrogen protection device, and react at 70 °C for 3 hours to end. The intermediate M2 is for standby;

[0040] Hybrid polymer P1:

[0041] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 70 g of p-hydroxystyrene, 20 g of acrylamide, 10 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 10 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P1 after drying in vacuo at 45 °C.

[0042] Hybrid polymer P2:

[0043] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 70 g of p-hydroxystyrene, 20 g of acrylamide, 10 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 20 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P2 after drying in vacuo at 45 °C.

[0044] Hybrid polymer P3:

[0045] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 60 g of p-hydroxystyrene, 30 g of acrylamide, 10 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 10 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P3 after drying in vacuo at 45 °C.

[0046] Hybrid polymer P4:

[0047] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 50 g of p-hydroxystyrene, 40 g of acrylamide, 10 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 30 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P4 after drying in vacuo at 45 °C.

[0048] Hybrid polymer P5:

[0049] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 40 g of p-hydroxystyrene, 40 g of acrylamide, 20 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 10 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water for precipitation, wash with water and filter, and obtain the hybrid polymer P5 after vacuum drying at 45 °C.

[0050] Hybrid polymer P6:

[0051] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 30 g of p-hydroxystyrene, 50 g of acrylamide, 20 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 50 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water for precipitation, wash with water and filter, and obtain the hybrid polymer P6 after vacuum drying at 45 °C.

[0052] Hybrid polymer P7:

[0053] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 20 g of p-hydroxystyrene, 60 g of acrylamide, 20 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 70 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water for precipitation, wash with water and filter, and obtain the hybrid polymer P7 after vacuum drying at 45 °C.

[0054] Hybrid polymer P8:

[0055] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 10 g of p-hydroxystyrene, 70 g of methacrylamide, 20 g of acrylic acid, 1 g of azobisisobutyronitrile, and 777700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 100 g of M1 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water for precipitation, wash with water and filter, and obtain the resin P8 after vacuum drying at 45 °C.

[0056] Chemical-resistant resin P9:

[0057] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 10 g of p-hydroxystyrene, 60 g of acrylamide, 30 g of acrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 40 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P9 after drying in a vacuum at 45 °C.

[0058] Hybrid polymer resin P10:

[0059] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 70 g of p-hydroxystyrene, 10 g of acrylamide, 20 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 10 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P10 after drying in a vacuum at 45 °C.

[0060] Hybrid polymer P11:

[0061] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 40 g of p-hydroxystyrene, 30 g of methacrylamide, 30 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 80 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P11 after drying in a vacuum at 45 °C.

[0062] Hybrid polymer P12:

[0063] In a 1000 ml four-necked flask equipped with a temperature-controlled heating, mechanical stirring, condensation reflux, and nitrogen protection device, add 30 g of p-hydroxystyrene, 40 g of acrylamide, 30 g of methacrylic acid, 1 g of azobisisobutyronitrile, and 700 g of dimethylformamide. Stir evenly and react at 70 °C for 8 hours. Add 100 g of M2 and continue to react for 30 minutes. Cool down to end the reaction. Drop the reaction stock solution into deionized water to precipitate, wash with water and filter, and obtain the hybrid polymer P12 after drying in a vacuum at 45 °C.

[0064] Example 1

[0065] Preparation of the base plate: A1050 rolled aluminum plate with a purity of 99.5% and a thickness of 0.3 mm is etched in a 5% sodium hydroxide aqueous solution at 70 °C for 20 seconds. After rinsing with running water, it is immediately neutralized with a 1% nitric acid aqueous solution. Then, in a 1% hydrochloric acid aqueous solution, it is coarsened electrolytically at 40 °C with a sine-wave alternating current at a current density of 50 A / dm² for 16 seconds. Next, at 40 °C, it is neutralized with a 5% sodium hydroxide aqueous solution for 10 seconds and washed with water. Finally, at 30 °C, it is anodized in a 20% sulfuric acid aqueous solution at a current density of 15 A / dm² for 20 seconds and washed with water. It is subjected to a sealing treatment with a 5% sodium silicate aqueous solution at 80 °C for 18 seconds, washed with water, and dried. The base plate obtained in this way has an average roughness of the center line of 0.5 μm and an oxide film weight of 3.0 g / dm².

[0066] Coating of the thermosensitive layer: The coating liquid of the following thermosensitive layer is extruded and coated on the base plate that has been subjected to hydrophilic treatment above, and then dried at 100 °C for 60 seconds to obtain a dry coating weight of 1.5 g / m². Components of the thermosensitive layer (each component by weight):

[0067] Hybrid polymer: 40 g of P1 resin

[0068] Phenolic resin: 40 g of BTB225 resin

[0069] Sensitizer: 10 g of phenobarbital

[0070] Infrared absorption dye ADS830: 5 g

[0071] Background dye: 5 g of methyl violet

[0072] The above components of the thermosensitive layer are added with 700 g of propylene glycol methyl ether and 0.5 g of surfactant (BYK306) to prepare the coating liquid of the thermosensitive layer. The sensitizer is 5-ethyl-5-phenyl-1-methyl-2,4,6-(1H,3H,5H)-pyrimidinetrione, abbreviated as phenobarbital; the structure of the infrared absorption dye ADS830 is: 2-(2-{2-chloro-3-[2-(1,1,3-trimethyl-2,3-dihydro-1H-benzo[e]indol-2-ylidene)ethylidene]-1-cyclohexenyl}-1-ethenyl)-1,1,3-trimethyl-1H-benzo[e]indolium 4-methyl-1-benzenesulfonate, purchased from American Dye source inc., Montreal, Canada.

[0073] Methods for testing the thermosensitive plate:

[0074] 1. Chemical resistance detection method: The above plate sample is immersed in a solution of isopropyl alcohol and water (mass ratio 1:1) at 23 °C for 30 minutes, rinsed with deionized water, and the coating loss of the plate is measured. The test results are shown in Table 3.

[0075] 2. Sensitivity test: On a SCREEN8600E plate-making machine, use the built-in test strip, imaging screening 175lpi, output resolution 2400dpi, drum speed (rpm) 800, exposure intensity starting value 40%, exposure intensity step interval 2%, exposure number 20; use Wangchang developer, Lucky Huaguang developer TPD-83, development temperature 25℃, development speed 25 seconds (100cm / min), developer conductivity controlled at 89-91ms / cm, dynamic replenishment of developer 120ml / m2, perform scanning and platemaking with different laser energies on the sample, and then determine the exposure laser amount using the following method, which is its sensitivity. Use X-rite's density reflectometer IC-Plate2 to measure the 50% flat screen value under different exposure energies until the display value of 50% flat screen area in the scale bar is found within the range of 49.5% -50.4%. This value is the sensitivity of the plate. The test results are shown in Table 3.

[0076] 3. Development latitude test: On the SCREEN8600E platemaking machine, exposure is performed at 1.1 times the sensitivity value obtained above, and the sample is scanned and plated with the built-in test strip. The sample is developed and processed at different development times. The difference between the highest and lowest development time that can make the plate meet the use requirements (no bottom left in the blank area, density OD value <0.29; no film reduction in the coating, density loss ≤4%; dot reduction 2-99%) is the development latitude of the plate. The test results are shown in Table 3.

[0077] 4. Determination of printing run rate: The above plate samples were put into normal printing (Beiren four-color four-opening high-speed rotary printing press) to examine their printing run rate. The test results are shown in Table 3.

[0078] The components of the thermal-sensitive layer in Examples 2-9 are shown in Table 1 below. The other preparation methods and methods for testing the thermal-sensitive plate are the same as those in Example 1. The test results are shown in Table 3.

[0079] Table 1:

[0080]

[0081] Among them, phenolic resin BTB225 resin comes from Weihai Tiancheng Chemical Co., Ltd., polyparahydroxystyrene PVPH80 comes from Lucky Huaguang Printing Technology Co., Ltd., and infrared absorption dye LC-01 comes from Honywell.

[0082] The components of the heat-sensitive layer in Comparative Examples 1-3 are shown in Table 2 below. Ordinary heat-sensitive plates Comparative Examples 1-3 are prepared and tested in the same manner as in Example 1. The test results are shown in Table 3.

[0083] Table 2:

[0084]

[0085] Among them, the phenolic resin BTB225 resin is from Weihai Tiancheng Chemical Co., Ltd., the poly(p-hydroxystyrene) PVPH80 is from Lucka Huaguang Printing Technology Co., Ltd., the infrared absorption dye LC-01 is from Honywell Company, and the solvent inhibitor NINS is from Weihai Tiancheng Chemical Co., Ltd.

[0086] Table 3

[0087]

[0088] The detection application results in Table 3 show that, compared with the first-generation thermal plates with a solvent inhibition and dissolution promotion mechanism, the chemical-resistant thermal plates with a second-generation supramolecular hydrogen bond association mechanism designed in the present invention contain hybrid polymers with excellent chemical resistance, imaging ability, and printing durability: the special sensitizer contains an aromatic ring structure, and it has good compatibility with the phenolic resin and hybrid resin that also have aromatic ring structures, avoiding the transfer of small molecules, and the plate has excellent chemical resistance.

[0089] The above are only the preferred embodiments of the present invention, but the protection scope of the present invention is not limited thereto. It should be pointed out that for those skilled in the art and any person familiar with the technical field of the present invention, without departing from the overall concept of the present invention, equivalent substitutions or changes made according to the technical solutions and inventive concepts of the present invention, as well as several changes and improvements made, should also be regarded as the protection scope of the present invention.

Claims

1. A hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin, characterized in that: The polyvinyl alcohol derivative is a product obtained by the urethanization reaction of polyvinyl alcohol and isocyanate acrylate; the molecular structural unit of the polyacrylic acid resin contains at least a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: an acrylic acid copolymerization unit containing an alkali-soluble group; the hybridization method of the polyvinyl alcohol derivative and the polyacrylic acid resin is: first synthesize the polyacrylic acid resin, and add the polyvinyl alcohol derivative for hybridization in the later stage of the reaction for synthesizing the polyacrylic acid resin to obtain a hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin.

2. The hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin according to claim 1, wherein: The isocyanate acrylate is ethyl isocyanate acrylate or ethyl methyl isocyanate acrylate.

3. The hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin according to claim 1, characterized in that: The polyacrylic acid resin is a ternary free radical copolymer of copolymerization units a: p-hydroxystyrene, b: acrylamide or methacrylamide, and c: acrylic acid or methacrylic acid; wherein: in the polyacrylic acid resin, by weight percentage, the weight ratio of copolymerization unit a is 10-70%, the weight ratio of copolymerization unit b is 10-70%, and the weight ratio of copolymerization unit c is 10-30%.

4. Application of the hybrid polymer according to any one of claims 1-3 in a thermal printing plate.

5. A chemical-resistant thermal plate, characterized in that: The thermal printing plate includes a hydrophilic carrier and a thermal layer, wherein the thermal layer contains a hybrid polymer of a polyvinyl alcohol derivative and a polyacrylic acid resin, and a phenolic resin, and the hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin is the hybrid polymer according to any one of claims 1-3.

6. The chemical-resistant thermal plate according to claim 5, characterized in that: Wherein the thermal layer further contains a sensitizer; the thermal layer further contains an infrared absorption dye and a background dye.

7. The chemical-resistant thermal printing plate according to claim 6, characterized in that: By weight percentage, the phenolic resin accounts for 40-80% of the total solid content of the composition, the hybrid polymer of the polyvinyl alcohol derivative and the polyacrylic acid resin accounts for 10-50% of the total solid content of the composition, the sensitizer accounts for 1-10% of the total solid content of the composition, the infrared absorption dye accounts for 1-5% of the total solid content of the composition, and the background dye accounts for 1-5% of the total solid content of the composition.

8. The chemical-resistant thermal printing plate according to claim 6, wherein: The phenolic resin is at least one of m-cresol phenolic resin, m-cresol-p-cresol phenolic resin, phenol-p-cresol phenolic resin, o-cresol-p-cresol phenolic resin, phenol-o-cresol-p-cresol phenolic resin, phenol-m-cresol-p-cresol phenolic resin, and polyurethane-modified linear phenolic resin; The infrared absorption dye is a cyanine dye with an absorption peak at 750-850 nm; The background dye is any one of oil-soluble blue, basic brilliant blue, victoria pure blue, phthalocyanine blue, malachite green, dark green, phthalocyanine green, crystal violet, methyl violet, ethyl violet, dimethyl yellow, and fluorescent yellow.

9. The chemical-resistant thermal printing plate according to claim 6, characterized in that: The sensitizer is 5-ethyl-5-phenyl-1-methyl-2,4,6-(1H,3H,5H)-pyrimidinetrione.

10. The chemical-resistant thermal printing plate according to claim 5, characterized in that: The hydrophilic carrier is an aluminum plate base that has been electrolytically roughened, anodized, and subjected to a sealing treatment.

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