CN111324014A

CN111324014A - Purple laser photopolymerization lithographic printing plate precursor

Info

Publication number: CN111324014A
Application number: CN201811545389.2A
Authority: CN
Inventors: 李乐; 高峰; 李旭东; 王泳; 郭伟锋; 孙伟涛; 吴丹; 杨争光; 姜香宇
Original assignee: Lucky Huaguang Graphics Co Ltd
Current assignee: Lucky Huaguang Graphics Co Ltd
Priority date: 2018-12-17
Filing date: 2018-12-17
Publication date: 2020-06-23
Anticipated expiration: 2038-12-17
Also published as: CN111324014B

Abstract

The invention discloses a purple laser photopolymerization lithographic printing plate precursor, which comprises a substrate, a photopolymerization imageable layer arranged on the substrate and a water-soluble coating layer arranged on the photopolymerization imageable layer, wherein the photopolymerization imageable layer comprises modified nano silicon dioxide. The modified nano silicon dioxide is adopted, so that the wear resistance of the plate is greatly improved, a better photo-polymerization CTP plate with high printing resistance is provided, the consumption of the plate in long-stroke operation is reduced, the cost is reduced, and the working efficiency is improved.

Description

Purple laser photopolymerization lithographic printing plate precursor

Technical Field

The invention belongs to the technical field of lithographic printing plates, and particularly relates to a precursor of a violet laser photopolymerization lithographic printing plate.

Background

With the recent development of computer and semiconductor laser technologies, photosensitive polymer materials have been widely studied and applied as laser imaging materials. The lithographic printing technology has been completely moved from the traditional PS plate copying technology of laser photo film to the computer-to-plate technology (CTP technology for short), and CTP plates are gradually popularized. The CTP plates are various in types and include silver salt diffusion CTP plates, UV-CTP plates, photopolymerization CTP plates, thermosensitive CTP plates and the like which are more popular.

Photopolymerization is a method of polymerizing monomers by the action of light. The photoinitiated polymerization component has two types of direct photoinitiated polymerization and photosensitive polymerization. In the former, under the action of light, a photoinitiator generates active seeds (free radicals or cations) in an excited state to initiate the polymerization of monomers; the latter photosensitizers first absorb light, the molecules transition from a ground state to an excited state, and the initiator is decomposed by energy transfer or electron transfer to generate free radicals, which initiate polymerization of the active species (double bond-containing compound) in the imageable layer. Thus, the required light sensing ranges such as 830nm for infrared light, 532nm for green light, 488nm for blue light and 405nm for blue-violet light can be realized according to the absorption spectrum of the photosensitizer.

The ultraviolet laser CTP plate is exposed by ultraviolet laser with the wavelength of 405nm, the imageable layer in the exposed area is subjected to polymerization reaction and is solidified, and the imageable layer is dissolved in a developing solution and becomes insoluble. The unexposed areas are removed after development processing to form a blank area of the printing plate, and the exposed areas are cured and retained to form an image area of the printing plate. The plate making process is as follows:

exposure → preheating → washing → development → washing → sizing → printing plate

In conventional or "wet" lithography, ink receptive regions (called image areas) are created on a hydrophilic surface. When the surface is wetted with water and ink is applied, the hydrophilic regions retain water and repel ink, while the ink receptive regions accept ink and repel water. The ink is transferred to the surface of the material on which the image is to be reproduced. For example, the ink may first be transferred to an intermediate blanket (blanket), which in turn is used to transfer the ink to the surface of the material on which the image is to be reproduced.

The printing plate precursor with the common wear-resisting property can not better meet the use requirements of long-range users, and users often need two or more sets of plates to complete printing of printed matters, so that the use amount of the plates is increased, various consumptions in the plate making process are increased, the cost is increased, and the working efficiency is reduced.

Disclosure of Invention

The invention aims to solve the technical problems in the prior art, and provides a violet laser photopolymerization lithographic printing plate precursor and a preparation method thereof, which can enable a plate to have higher printing resistance, reduce the usage amount of the plate for a long-process user, save the cost and improve the working efficiency.

The object of the invention is achieved in the following way:

a violet laser photopolymerizable lithographic printing plate precursor comprising a substrate, a photopolymerizable imageable layer disposed on the substrate, the photopolymerizable imageable layer comprising modified nanosilica, and a water soluble coating layer disposed on the photopolymerizable imageable layer.

The modified nano silicon dioxide is micromolecular modified nano silicon dioxide.

The micromolecule modified nano silicon dioxide is any one of silane coupling agent, epoxy chloropropane, toluene diisocyanate, ethyl methacrylate isocyanate, bisphenol type glycidyl ether and glycidyl methacrylate.

The structural formula of the silane coupling agent is RSiX₃Wherein X is a hydrolytic group and R is an organic chain segment with functional groups.

The modified nano silicon dioxide is macromolecular polymer modified nano silicon dioxide.

The macromolecular polymer in the macromolecular polymer modified nano silicon dioxide is any one of polystyrene, polymethyl methacrylate, polyurethane, polylactic acid, polyglycidyl methacrylate, polyaniline and polyamide.

The particle size of the modified nano silicon dioxide is 5-100nm, preferably 10-70 nm.

The modified nano silicon dioxide accounts for 1-15% of the total weight of the photopolymerisable imageable layer, and the optimal percentage of the modified nano silicon dioxide accounts for 3-10% of the total weight of the photopolymerisable imageable layer.

The photopolymerizable imageable layer includes a modified nanosilica, a polymeric binder, a free-radically polymerizable component, an initiator composition capable of generating free radicals upon exposure to imaging radiation, and a radiation absorbing compound.

The photopolymerizable imageable layer has a thickness of 0.2 to 3 μm, preferably 0.3 to 2 μm, and more preferably 0.4 to 1.8 μm.

The thickness of the water-soluble coating layer is 0.1 to 2 μm, preferably 0.2 to 2 μm, and more preferably 0.4 to 1.6 μm.

Compared with the prior art, the modified nano-silica is adopted, so that the wear resistance of the plate is greatly improved, a better photo-polymerization CTP plate with high printing resistance is provided, the consumption of the plate in long-stroke operation is reduced, the cost is reduced, and the working efficiency is improved.

Detailed Description

The specific process for producing such a photopolymerizable lithographic printing plate precursor is described below in detail.

A substrate

The substrate of the present invention consists of an aluminum support that can be treated using techniques known in the art, including some type of roughening by physical (mechanical) graining, electrochemical graining, or chemical graining, typically followed by acid anodization. Typically the hydrophilic lithographic substrate is an electrochemically grained and sulfuric or phosphoric acid anodized aluminum support that provides a hydrophilic surface for lithography.

Anodic sulfate of aluminum supportThe poling typically provides at least 1.5g/m on the surface²And up to and including 5g/m²And more typically at least 3g/m²And up to and including 4.3g/m²Oxide weight (coverage). Phosphoric acid anodization typically provides at least 1.5g/m of the surface²And up to and including 5g/m²And more typically at least 1g/m²And up to and including 3g/m²Oxide weight of (c).

The hydrophilicity can be increased by forming the intermediate layer by treating the aluminum support with, for example, a silicate, dextrin, calcium zirconium fluoride, hexafluorosilicic acid, poly (vinylphosphonic acid) (PVPA), vinylphosphonic acid copolymer, poly [ (meth) acrylic acid ], or acrylic acid copolymer. In addition, the aluminum support may be treated with a phosphate solution additionally containing an inorganic fluoride (PF).

Known procedures can be used to electrochemically buff, sulfuric acid anodize, and treat the aluminum support with PVPA or PF to improve surface hydrophilicity.

Second, formation of imageable layer

A coating of a photopolymerizable photosensitive composition is applied to a substrate and dried to form an imageable layer.

The photopolymerizable photosensitive composition is dissolved and dispersed at a solid content concentration of 2 to 50 wt%, applied to a substrate, and dried. The amount of the layer (imageable layer) of the photopolymerizable photosensitive composition applied to the substrate varies depending on the application, and it is generally preferred that the thickness of the coating after drying is from 0.4 μm to 1.8. mu.m.

The photopolymerizable photosensitive composition used in the present invention for forming the imageable layer of the photosensitive lithographic printing plate contains modified nano-silica, a polymer binder, a radical polymerizable component, a radiation absorber, and an initiator as essential components, and if necessary, various compounds such as a colorant, a plasticizer, a thermal polymerization inhibitor, and a surfactant may be used in combination.

The photopolymerizable lithographic printing plate of the present invention comprises modified nanosilica in the photopolymerizable imageable layer.

The nano silicon dioxide is generally amorphous white powder, is a non-toxic, tasteless and pollution-free inorganic non-metallic material, has a particle size of 5-150nm, and can be prepared by two methods, namely a dry method and a wet method, wherein the dry method comprises a gas phase method and an electric arc method, and the wet method comprises a chemical precipitation method and a sol-gel method. The molecular structure of the nano silicon dioxide is a three-dimensional network structure, hydroxyl groups in different bonding states exist on the surface, the hydroxyl groups have hydrophilicity, and particles are easy to agglomerate.

By adding the nano silicon dioxide particles, the mechanical property, heat resistance, impact resistance, weather resistance and surface properties of the polymer nano composite material such as wear resistance, scratch resistance and the like can be obviously improved.

By modifying the surface of the nano silicon dioxide, the problem of mutual agglomeration of nano silicon dioxide particles can be solved, different reaction groups can be carried on the surface of the nano silicon dioxide particles, the dispersibility of the particles in a polymer is improved, the interface compatibility of the particles and the polymer is improved, a space network structure is formed, and the performance of the material is improved. In addition, more research reports show that proper modifier is selected to modify the surface of the silicon dioxide, and when the addition amount is high, the silicon dioxide is not agglomerated and is dispersed more uniformly, so that the performance of the nano composite material is greatly improved.

The silica surface modification method can be divided into two major categories, i.e., chemical modification by chemical bond action and physical modification by making a modifier adsorb on the particle surface by secondary chemical bond action. The chemical modification method is mainly characterized in that groups on the surface of the silicon dioxide particles, such as silicon hydroxyl groups, and groups of a modifier are utilized to graft modifier molecules on the surface of the nano particles through the chemical covalent bond action, and the modifier is divided into a small molecule modifier and a large molecule modifier.

The micromolecule modifying agent can be one of micromolecule modifying agents such as silane coupling agent, epoxy chloropropane, toluene diisocyanate, ethyl methacrylate isocyanate, bisphenol type glycidyl ether, glycidyl methacrylate and the like, wherein the silane coupling agent is preferably selected. The basic structural formula is RSiX₃Wherein X is hydrolytic group, mainly contains chloro, ethoxy, methoxy, etc., and R is various functional groupsAn organic segment of a radical. The hydrolytic group and the hydroxyl on the surface are subjected to two-step reaction of hydrolysis and dehydration condensation, so that a hydrophobic chain segment with a functional group can be grafted to the surface, the surface can be changed from hydrophilicity to lipophilicity, and the hydrophilic and lipophilic hydrophobic chain segment can be uniformly dispersed in solvents and polymers with different polarities.

The macromolecular polymer is modified nano silicon dioxide, and the macromolecular polymer can be one of polystyrene, polymethyl methacrylate, polyurethane, polylactic acid, polyglycidyl methacrylate, polyaniline and polyamide. There are two main approaches to silica graft polymerization, namely, surface polymerization growth grafting and coupling grafting.

The modified nano silicon dioxide accounts for 1-15% of the total weight of the photopolymerized imageable layer, and preferably 3-10%.

The photopolymerizable photosensitive compositions used in the precursors of the invention generally include one or more polymeric binders that facilitate the developability of the imaging precursor. Useful polymeric binders can be homogeneous, i.e., film-forming, non-particulate, or soluble in the coating solvent. Such polymeric binders include, but are not limited to, (meth) acrylic and (meth) acrylate resins [ e.g., (meth) acrylates ], polyvinyl acetals, phenolics, polymers derived from styrene, N-substituted cyclic imides, or maleic anhydride, such as those described in EP1,182,033A1 (Fujimaki et al) and U.S. Pat. No. 6,309,792 (Hauck et al), 6,352,812 (Shimazu et al), 6,569,603 (Furukawa et al), and 6,893,797 (Munnelly et al). Also useful are the vinylcarbazole polymers described in U.S. patent 7,175,949 (Tao et al), and polymers having pendant vinyl groups as described in U.S. patent 7,279,255 (Tao et al). Usable are random copolymers derived from polyethylene glycol methacrylate/acrylonitrile/styrene monomer in a random manner and in a particulate form, dissolved random copolymers derived from carboxyphenyl/methacrylamide/acrylonitrile/methacrylamide/N-phenylmaleimide, random copolymers derived from polyethylene glycol/methacrylate/acrylonitrile/vinylcarbazole/styrene/methacrylic acid, random copolymers derived from N-phenylmaleimide/methacrylamide/methacrylic acid, random copolymers derived from urethane-acrylate (urethane-acrylic) intermediate A (reaction product of p-toluenesulfonyl isocyanate and hydroxyethyl methacrylate)/acrylonitrile/N-phenylmaleimide, and random copolymers derived from N-methoxymethylmethacrylamide/methacrylic acid/acrylonitrile/N-phenylmaleimide. "random" copolymers refer to the conventional use of the term, i.e., structural units in the polymer backbone derived from the monomers are arranged in random order, as opposed to block copolymers, although two or more of the same structural units may be accidentally present in the chain.

The polymeric binder may be selected from any alkaline solution soluble (or dispersible) polymer having an acid number of at least 20meq KOH/g of polymer and up to and including 400meq KOH/g of polymer. The following polymeric binders may be used in this manner, but this is not an exhaustive list:

I. film-forming polymers formed by polymerization of combinations or mixtures of the following, as described, for example, in U.S. patent 7,326,521 (Tao et al): (a) (meth) acrylonitrile, (b) poly (alkylene oxide) esters of (meth) acrylic acid, and optionally (c) meth (acrylic acid), (meth) acrylic acid esters, styrene and its derivatives, and (meth) acrylamide. Some particularly useful polymeric binders in this category are derived from one or more of (meth) acrylic acid, (meth) acrylates, styrene and its derivatives, vinylcarbazole, and poly (alkylene oxide) (meth) acrylates.

Film-forming polymers having allyl ester side groups as described in U.S. patent 7,332,253 (Tao et al). Such polymers may also include pendant cyano groups or have repeat units derived from various other monomers.

A film-forming polymer having an all-carbon backbone, wherein at least 40 mole% and up to and including 100 mole% (and typically at least 40 mole% and up to and including 50 mole%) of the carbon atoms making up the all-carbon backbone are tertiary carbon atoms, and the remaining carbon atoms in the all-carbon backbone are non-tertiary carbon atoms. Such polymeric binders are described in more detail in U.S. patent application publication 2008-0280229 (Tao et al).

A film-forming polymeric binder having one or more pendant ethylenically unsaturated groups (reactive vinyl groups) attached to the polymer backbone. Such reactive groups are capable of polymerizing or crosslinking in the presence of free radicals. The pendant group may be directly connected to the polymer main chain via a carbon-carbon direct bond, or connected to the polymer main chain through a linking group which is not particularly limited. The reactive vinyl group may be substituted with at least one halogen atom, a carboxyl group, a nitro group, a cyano group, an amide group, or an alkyl, aryl, alkoxy, or aryloxy group, and in particular one or more alkyl groups. In some embodiments, the reactive vinyl group is attached to the polymer backbone through a phenylene group, as described, for example, in U.S. Pat. No. 6,569,603 (Furukawa et al). Other useful polymeric binders have vinyl groups within the pendant groups described, for example, in EP1,182,033A1 (Fujimaki et al) and U.S. Pat. Nos. 4,874,686 (Urabe et al), 7,729,255 (Tao et al), 6,916,595 (Fujimaki et al), and 7,041,416 (Wakata et al), particularly for formulas (1) through (3) described in EP1,182,033A1.

V. As described in U.S. patent application publication 2009-0142695 (Baumann et al), the film-forming polymeric binder may have pendant 1H-tetrazole groups.

The total polymeric binder is typically present in the photopolymerizable imageable layer in an amount of at least 5 weight% and up to and including 70 weight%, or typically at least 40 weight% and up to and including 70 weight%, of the total dry weight of the photopolymerizable imageable layer.

The photopolymerizable photosensitive composition comprises one or more radically polymerizable components, each component containing one or more radically polymerizable groups polymerizable using radical initiation. For example, such free radically polymerizable components can contain one or more free radically polymerizable monomers or oligomers having one or more addition polymerizable ethylenically unsaturated groups, crosslinkable ethylenically unsaturated groups, ring-opening polymerizable groups, azido groups, aryl diazonium salt groups, aryl diazonium sulfonate groups, or combinations thereof. Similarly, crosslinkable polymers having such free radically polymerizable groups can also be used. Oligomers or prepolymers such as urethane acrylates and methacrylates, epoxy acrylates and methacrylates, polyester acrylates and methacrylates, polyether acrylates and methacrylates, and unsaturated polyester resins may be used. In some embodiments, the free radically polymerizable component comprises a carboxyl group.

Further, an initiation component including a radiation absorber, an initiator and a co-initiator is contained in the imageable layer as the photosensitive lithographic printing plate of the present invention.

The radiation absorber is a radiation-sensitive composition that is sensitive to "violet" radiation in the range of at least 375 nm and up to and including 475 nm. Sensitizers useful in such compositions include certain pyrylium (pyrilium) and thiopyrylium dyes and 3-coumarinone.

Some other useful sensitizers for such spectral sensitivity are described, for example, in U.S. patent 6,908,726 (Korionoff et al) and WO 2004/074929 (Baumann et al), which describe useful bisoxazole derivatives and analogs, and also in U.S. patent application publications 2006/0063101 and 2006/0234155 (both Baumann et al).

Other useful sensitizers are those having suitable aromatic or heteroaromatic units which provide a conjugated pi-system between two heteroatoms.

Another useful "violet" -visible radiation sensitizer is the compound described in WO 2004/074929 (Baumann et al). These compounds include the same or different aromatic heterocyclic groups attached with a spacer moiety that contain at least one carbon-carbon double bond conjugated to the aromatic heterocyclic group.

Other sensitizers which may be used for sensitizing in the violet region are 2,4, 5-triaryloxazole derivatives as described in WO 2004/074930 (Baumann et al) these compounds may be used alone OR together with a co-initiator as described above useful 2,4, 5-triaryloxazole derivatives may be represented by the structure G- (Ar1)3 wherein Ar1 is the same OR different substituted OR unsubstituted carbocyclic aryl group having from 6 to 12 carbon atoms in the ring, G is a furan OR oxazole ring, OR the structure G- (Ar1)2 wherein G is an oxadiazole ring Ar1 group may be substituted with one OR more halogen, substituted OR unsubstituted alkyl, substituted OR unsubstituted cycloalkyl, substituted OR unsubstituted aryl, amino (primary, secondary OR tertiary) OR substituted OR unsubstituted alkoxy OR aryloxy groups whereby the aryl group may be substituted with one OR more R '1 to R '3 groups independently hydrogen OR substituted OR unsubstituted alkyl groups having from 1 to 20 carbon atoms (such as methyl, ethyl, N-hexyl, and N-substituted OR unsubstituted alkyl groups such as R ' 5-phenyl) OR substituted OR tertiary alkyl groups wherein each of R '5, 5-OR 5-methyl and R ' 5-phenyl groups may be the same OR different in the ring, wherein R's 466, 5, OR 5 ' and R's, 5's may be substituted with one OR 3 groups, such as defined in the same OR three carbon atoms in the ring.

Another useful class of violet radiation sensitizers includes compounds represented by the structure Ar1-G-Ar2, wherein Ar1 and Ar2 are the same or different substituted or unsubstituted aryl groups having from 6 to 12 carbon atoms in the ring, or Ar2 can be an arylene-G-Ar 1 or arylene-G-Ar 2 group, and G is a furan, oxazole or oxadiazole ring. Ar1 is as defined above, and Ar2 may be the same or different aryl group as Ar 1. The "arylene group" may be any of the aryl groups defined for Ar1, but with the hydrogen atom removed to impart divalent properties thereto.

The total amount of the one or more radiation absorbing compounds is at least 1 weight% and up to and including 30 weight%, or typically at least 5 weight% and up to and including 20 weight%, based on the total solids of the photopolymerizable imageable layer.

The initiator composition includes one or more initiators capable of generating radicals sufficient to initiate polymerization of all of the various free radically polymerizable components upon exposure of the composition to imaging radiation. The initiator composition is typically responsive to exposure radiation in, for example, a desired spectral region, for example, the violet region at 450nm and typically at least 350nm and up to and including 450 nm.

More typically, the initiator composition includes one or more electron acceptors and one or more coinitiators capable of donating electrons, hydrogen atoms, or hydrocarbon groups.

In general, suitable initiator compositions for use in the photopolymerizable photosensitive compositions include initiators including, but not limited to, aromatic sulfonyl halides, trihalomethyl sulfones, imides (e.g., N-benzoyloxyphthalimides), diazosulfonates, 9, 10-dihydroanthracene derivatives, N-aryl, S-aryl or O-aryl polycarboxylic acids (e.g., anilinodiacetic acid and its derivatives, and other "coinitiators" described in U.S. Pat. No. 5,629,354 to West et al), oxime ethers and oxime esters (e.g., those derived from benzoin), α -hydroxy or α -aminoacetophenone, trihalomethyl-aryl sulfones, benzoin ethers and esters, hydroperoxides (e.g., benzoyl peroxide), hydroperoxides, azo compounds (e.g., azobisisobutyronitrile), 2,4, 5-triarylboron-containing dimers (also known as hexaaryldiimidazoles, or "BI"), trihalomethyl-substituted triazines, tetraarylalkyl substituted triazines (e.g., such as described in U.g., U.S. Pat. No. 4,565,769(Dueber et al), 2,4, 5-triarylboron-containing dimers (also known as hexaaryldiimidazoles, or "halomethyl salts"), triazines (e.g., triazines), tetraarylonium salts), and iodonium salts, such as described in U.g., organoboron, aryl-onium salts, such as described in U.g., U.S. Pat. pat.

Hexaarylbiimidazoles, onium compounds and thiol compounds and mixtures of two or more thereof are desirable co-initiators or free radical generators, and especially hexaarylbiimidazoles and mixtures thereof with thiol compounds are useful. Suitable hexaaryldiimidazoles are also described in U.S. Pat. Nos. 4,565,769(Dueber et al) and 3,445,232 (Shirey) and may be prepared according to known methods, such as oxidized dimers of triarylimidazoles.

The amount of initiator composition in the photopolymerizable imageable layer will be readily apparent to those skilled in the art and will depend on the particular photopolymerizable photosensitive composition to be used.

Additional additives to the photopolymerizable imageable layer include a color developer or an acidic compound. The color developers are intended to include monomeric phenolic compounds, organic acids or metal salts thereof, hydroxybenzoates, acidic clays, and other compounds described in, for example, U.S. patent application publication 2005/0170282 (Inno et al). The imageable layer can also include a variety of optional compounds including, but not limited to: dispersants, wetting agents, plasticizers, surfactants for coatability or other properties, tackifiers, pH adjusters, drying agents, defoamers, preservatives, antioxidants, development aids, rheology modifiers, or combinations thereof, or any other addenda commonly used in the lithographic art, in conventional amounts.

Thirdly, outermost water-soluble coating layer

The precursor has an outermost water-soluble coating layer disposed directly on the photopolymerizable imageable layer, and it is generally preferred that the coating thickness be present from 1 to 1.2 μm after drying.

The outermost water-soluble coating layer of the photopolymerizable photosensitive group constituting the imageable layer of the photosensitive lithographic printing plate used in the present invention comprises one or more film-forming water-soluble polymer binders present in an amount of at least 60 wt% and up to and including 98 wt% based on the total dry weight of the outermost water-soluble coating layer.

Such film-forming, water-soluble polymeric binders typically comprise modified or unmodified polyvinyl alcohols having a saponification degree of at least 30%, or a saponification degree of at least 75%, or a saponification degree of at least 90%, and a saponification degree of up to and including 99.9%.

For example, the outermost water-soluble coating layer may comprise one or more film-forming, water-soluble polymeric binders comprising at least one modified polyvinyl alcohol modified with at least 0.1mol% of one or more identical or different groups selected from: carboxylic acid groups, sulfonic acid groups, acetoacetyl groups, alkylene groups, silanol groups, amino groups, thioalkyl groups, diol groups, sulfate groups, phosphonate groups, and phosphate groups.

Further, one or more acid-modified poly (vinyl alcohol) s may be used as a film-forming water-soluble polymer binder in the outermost water-soluble coating layer. For example, at least one modified poly (vinyl alcohol) can be modified with an acidic group selected from the group consisting of carboxylic acid groups, sulfonic acid groups, sulfate groups, phosphonic acid groups, and phosphate groups. Examples of such materials include, but are not limited to, sulfonic acid modified poly (vinyl alcohol), carboxylic acid modified poly (vinyl alcohol), and quaternary ammonium salt modified poly (vinyl alcohol), or combinations thereof. Specific commercial examples of such acid-modified poly (vinyl alcohol) s include SD1000 available from Kuraray, and Gohsefimer K-210, Gohseran L-3266, and Gohseran CKS-50 available from Nippon Gohsei.

The outermost water-soluble coating layer may further comprise one or more other film-forming water-soluble polymers other than poly (vinyl alcohol), for example in an amount of at least 2 wt% and up to and including 40 wt%, the other film-forming water-soluble polymer being poly (vinyl pyrrolidone), poly (ethyleneimine), poly (vinyl imidazole), poly (vinyl caprolactone), or a random copolymer derived from two or more of vinyl pyrrolidone, ethyleneimine, vinyl caprolactone, vinyl acetate and vinyl imidazole, and vinyl acetamide.

Alternatively, the outermost water-soluble coating layer may be formed primarily using one or more film-forming, water-soluble polymeric binders such as poly (vinylpyrrolidone), poly (ethyleneimine), poly (vinylimidazole), gelatin or gelatin derivatives, cellulose derivatives, and random copolymers from two or more of vinylpyrrolidone, ethyleneimine and vinylimidazole, as well as mixtures of such polymers.

The outermost water-soluble coating layer formulation may also include cationic, anionic, amphoteric and nonionic wetting agents or surfactants, flow improvers or thickeners, defoamers, colorants, and biocides. Details on such addenda, as well as the amounts that can be used, are provided in WO 99/06890 (Pappas et al), EP1,788,429 (Loccufier et al), and U.S. patent application publications 2005/0266349 (Van Damme et al), 2007/0231739 (Koizumi), 2007/0231740 (Yanaka et al), and 2011/0053085 (Huang et al).

In some preferred embodiments, the outermost water-soluble coating layer consists essentially of the one or more film-forming, water-soluble polymeric binders.

Production of photopolymerizable lithographic printing plate precursor:

the above-described photopolymerizable photosensitive composition may be applied to the substrate as a solution or dispersion in a coating liquid using any suitable equipment and procedure, such as spin coating, blade coating, gravure coating, die coating, slot coating, bar coating, wire-wound rod coating, roll coating, or extrusion hopper coating. Typically, the photopolymerizable photosensitive composition is applied and dried to form the imageable layer.

An exemplary such manufacturing process is to mix the various components required for imaging chemistry in a suitable organic solvent or mixture thereof [ e.g., methyl ethyl ketone (2-butanone), methanol, ethanol, 1-methoxy-2-propanol, isopropanol, acetone, gamma-butyrolactone, n-propanol, tetrahydrofuran, and other solvents well known in the art, and mixtures thereof ], apply the resulting solution to a substrate, and remove the solvent by evaporation under suitable drying conditions.

A suitable outermost water-soluble coating layer formulation may be applied to the dried negative-working imageable layer in a suitable described method, typically water as the solvent, followed by drying to form the outermost water-soluble coating layer.

The present invention will be described with reference to examples, but the present invention is not limited to these examples.

Examples 1 to 6 and comparative examples 1 to 2

An aluminum coil having a thickness of 0.30mm and having been rolled (coil-like) was fixed to a feeder. The aluminum plate continuously fed out from the feeder was immersed in 10% sodium hydroxide at 70 ℃ for 60 seconds at the surface treatment part, etched, washed with running water, and then washed with 20% HNO₃And performing neutralization washing and water washing. Using a sine wave alternating waveform current at VA of 12.7V in a 1% nitric acid aqueous solution at 300 coulombs/dm²The electrolytic surface roughening treatment is carried out on the anode by the electric power. The surface roughness was measured and found to be 0.6um (Ra).

Then immersed in 30% H₂SO₄In an aqueous solution, after desmutting was carried out at 55 ℃ for 2 minutes, 20% H was added at 33 ℃ to₂SO₄In an aqueous solution, a cathode was disposed on a ground surface at a current density of 5A/dm²Then, anodic oxidation was carried out for 50 seconds to a thickness of 2.7g/m². In this case, the anodic oxide coating on the back surface was about 0.5g/m in the center of the aluminum plate²At the end of about 1.0g/m²。

The following hydrophilic layer coating compositions were mixed and stirred at 30 ℃. After about 5 minutes, heat was generated, and after 60 minutes of reaction, the contents were transferred to another container, and 10000 parts by weight of methanol was further added to prepare a primer coating.

Liquid composition for undercoating:

methanol 100 parts by weight

120 parts by weight of water

10 parts by weight of phosphoric acid (85% aqueous solution)

25 parts by weight of 3-methacryloxypropyltriethoxysilane

The liquid coating was applied to the treated aluminum plate to a level of 0.1g/m²Drying is carried out until the aluminum temperature reaches 70 ℃, and then cooling is carried out until the aluminum temperature reaches below 50 ℃.

On the thus obtained undercoat layer, a highly sensitive photopolymerizable composition having the following composition was applied so that the dry coating weight became 1.6g/m²Drying until the aluminum temperature reaches 100 ℃, and then carrying out dryingCooling is carried out until the aluminum temperature reaches below 50 ℃.

Imageable layer coating liquid composition:

preparing micromolecule modified nano silicon dioxide:

adding cetyl trimethyl ammonium bromide into ethanol to prepare ethanol solution, heating to 80 ℃ in a three-neck flask, and adding nano SiO₂Stirring for 2h under reflux, centrifuging for 30 min, oven drying at 80 deg.C, adding the above dried nano-silica into ethanol solution of silane coupling agent KH-570, stirring for 2h under reflux, centrifuging for 30 min, and oven drying at 80 deg.C.

Preparing macromolecular modified nano silicon dioxide:

adding 1.25g of isophorone-diisocyanate, 1.8g of polymethyl methacrylate and 0.005g of catalyst dibutyltin dilaurate into a three-neck flask, stirring and reacting at a constant temperature of 50 ℃ for 1.5h, measuring the content by a di-n-butylamine method, taking the semi-blocked oligomer, adding 1.2g of KH-570 modified nano silicon dioxide when the content is close to a theoretical value, stirring and reacting at room temperature in an acetone solution for 2h, centrifuging and washing with acetone for 3 times, and drying at 80 ℃.

Wherein: a: a methyl methacrylate/methacrylic acid copolymer (molecular weight 8 ten thousand, acid value 70 mg-KOH/g),

b: polyurethane acrylate (SARTOMER, CN970A 60) is a prepolymer,

c: acrylate oligomer (SARTOMER, CN 549) is prepolymer,

d: polyfunctional monomers (SR 531, SARTOMER Co.), which are unsaturated monomers,

e: the phthalocyanine pigment dispersion (acrylic resin coated 15: 1 copper phthalocyanine), is a colorant,

f: a fluorine-based nonionic surfactant (FC-202, 3M Co.),

g: o-chloro-hexaaryl-bisimidazole as an initiator,

h: 2-mercaptobenzothiazole,

i: 4- (4- (2-chlorophenyl) -2-phenyl-5-oxazolyl) -N, N-diethyl-aniline as a photosensitizer,

j: methyl ethyl ketone, which is a solvent,

k: propylene glycol monomethyl ether acetate, is a solvent.

L: the nano silicon dioxide is modified by small molecules,

m: macromolecular modified nano silicon dioxide.

Ultrasonically dispersing modified nano-silica in methyl ethyl ketone in advance, adding the modified nano-silica solution into the methyl ethyl ketone after other components are uniformly mixed, and uniformly stirring to obtain the photopolymerizable composition.

The photopolymerizable composition of the above composition was coated on an aluminum substrate to a coating thickness of 1.6g/m²Drying is carried out until the aluminum temperature reaches 100 ℃, and then cooling is carried out until the aluminum temperature reaches below 50 ℃.

Protective layer coating liquid composition:

25 parts by weight of polyvinyl alcohol (PVA 117, Kuraray Co.)

Polyvinylpyrrolidone (Shanghai reagent Co., Ltd., national drug group) 3 parts by weight

0.5 part by weight of a surfactant (Shanghai reagent Co., Ltd., national drug group, OP 15)

300 parts by weight of distilled water

The protective layer composition having the above composition was applied to the upper surface of the dried photopolymerizable composition to a dry coating thickness of 1.6 μm, dried until the aluminum temperature reached 100 ℃, and then cooled until the aluminum temperature reached 50 ℃ or less.

Evaluation of printing durability:

the photopolymerizable lithographic plate produced in the above manner was subjected to image exposure of the imageable layer with a violet laser at 405 or 410nm at an appropriate exposure dose to partially cure the visible light. By the development treatment, the unexposed portion of the photopolymerizable layer is removed, and an image can be formed on the surface of the aluminum plate support. Further, as described above, it is known that a protective coating having an oxygen barrier property is provided on the imageable layer of the photosensitive lithographic printing plate of the present invention, and the present invention performs a method of removing the protective coating and removing the unexposed portion of the imageable layer simultaneously using a developer.

The photosensitive lithographic printing plate thus developed is subjected to post-treatment with water, an eluent containing a surfactant or the like, and a non-fat-sensitive liquid containing gum arabic, a starch derivative or the like. The lithographic printing plate prepared by this process was mounted on an offset printing press for printing of multiple pages.

As can be seen from Table 2, the wear resistance of the plate is greatly improved by adopting the modified nano-silica, so that a better photo-polymerization CTP plate with high printing resistance is provided, the consumption of the plate in long-stroke operation is reduced, and the working efficiency is improved.

The foregoing is only a preferred embodiment of the present invention, and it should be noted that, for those skilled in the art, various changes and modifications can be made without departing from the overall concept of the present invention, and these should also be considered as the protection scope of the present invention.

Claims

1. A violet laser photopolymerizable lithographic printing plate precursor characterized in that: the photo-polymerizable imageable layer comprises modified nano silicon dioxide.

2. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the modified nano silicon dioxide is micromolecular modified nano silicon dioxide.

3. The violet laser photopolymerizable lithographic printing plate precursor according to claim 2, characterized in that: the micromolecule modified nano silicon dioxide is any one of silane coupling agent, epoxy chloropropane, toluene diisocyanate, ethyl methacrylate isocyanate, bisphenol type glycidyl ether and glycidyl methacrylate.

4. The violet laser photopolymerizable lithographic printing plate precursor according to claim 3, wherein: the structural formula of the silane coupling agent is RSiX₃Wherein X is a hydrolytic group and R is an organic chain segment with functional groups.

5. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the modified nano silicon dioxide is macromolecular polymer modified nano silicon dioxide.

6. The violet laser photopolymerizable lithographic printing plate precursor according to claim 5, wherein: the macromolecular polymer in the macromolecular polymer modified nano silicon dioxide is any one of polystyrene, polymethyl methacrylate, polyurethane, polylactic acid, polyglycidyl methacrylate, polyaniline and polyamide.

7. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the particle size of the modified nano silicon dioxide is 5-100 nm.

8. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the modified nano silicon dioxide accounts for 1-15% of the total weight of the photopolymerization imageable layer.

9. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the photopolymerizable imageable layer includes a modified nanosilica, a polymeric binder, a free-radically polymerizable component, an initiator composition capable of generating free radicals upon exposure to imaging radiation, and a radiation absorbing compound.

10. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the photopolymerizable imageable layer has a thickness of 0.2 to 3 μm.

11. The violet laser photopolymerizable lithographic printing plate precursor according to claim 1, wherein: the thickness of the water-soluble coating layer is 0.1-2 μm.