JPH0259978B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to halogen surface treatment of flexographic printing plates having a photosensitive layer containing a butadiene/acrylonitrile copolymer. More particularly, the invention relates to the surface treatment of photosensitive layers containing butadiene/acrylonitrile copolymers with bromine or iodine followed by chlorine and the products produced thereby. Photosensitive flexographic printing plates have achieved considerable importance in the printing industry.
Compositions particularly useful in the production of such flexographic printing plates include addition polymerizable ethylenically unsaturated compounds, photoinitiators and block copolymers such as styrene-butadiene-styrene and as polymer binders. Examples include compositions containing a styrene-isoprene-styrene copolymer or a butadiene/acrylonitrile polymer optionally containing carboxyl groups. Printing plates using compositions containing the block copolymers described above are generally compatible only with alcohol or alcohol-acetate based inks. On the other hand, butadiene/acrylonitrile polymers, which optionally contain carboxyl groups, are generally only compatible with hydrocarbon-based inks. Flexographic printing plates containing styrene-butadiene-styrene or styrene-isoprene-styrene block copolymer binders are generally treated with an acidic hypochlorite solution after imagewise exposure and development, for example through a process transparency. to reduce the tackiness of the layer. Reduction of tack can also be achieved by the use of bromine solutions. However, neither chlorination nor bromine treatment makes these block copolymer-based printing plates compatible with hydrocarbon-based inks. However, flexographic printing plates containing butadiene/acrylonitrile polymers, which optionally contain carboxyl groups, are not only sticky but also contain certain solvents and other components present in some printing inks, such as alcohols, Easily attacked by acetate and others. The use of these plates is therefore limited to a limited group of inks containing substantial amounts of hydrocarbon solvents. The use of chlorine-containing solutions, such as hypochlorite solutions, may reduce tackiness but does not prevent the printing surface of the printing plate from being attacked by inks containing alcohol and various other solvents. When flexographic printing plates containing butadiene/acrylonitrile polymers are treated with an aqueous solution having a free bromine concentration before or after post-exposure (total non-imagewise exposure performed after imagewise exposure), all inks It shows increased resistance to solvents, and most notably to alcohol-containing inks and various other non-hydrocarbon solvents. However, this improvement is insufficient for practical use when the alcohol-containing ink also contains high levels of acetate esters or other aggressive co-solvents. Chlorination, introduced for tack reduction, does not increase resistance and may reduce it. This improvement is also not observed upon chlorine or bromine treatment of printing plates containing styrene-isoprene-styrene or styrene-butadiene-styrene block copolymers. Styrene - Isoprene - Styrene, Styrene -
Flexographic printing plates containing butadiene-styrene block copolymers and flexographic printing plates containing butadiene/acrylonitrile copolymers, optionally containing carboxyl groups, are detackified by iodine treatment and are detackified by iodine treatment. given increased resistance to "curing". It is not known whether iodine treatment improves solvent resistance. For printing plates made from photosensitive compositions containing a butadiene/acrylonitrile copolymer, optionally containing carboxyl groups, the plates can be prepared using the inks, ink solvents and co-solvent spectra currently available to those skilled in the art (e.g. alcohol, There is a need for improved 2-halogen processing methods to make them compatible with alcohols (alcohol-acetates, hydrocarbons, alcohol-hydrocarbons, alcohol-water, etc.). There also exists a need for a process in which two halogen treatments, bromine and chlorine or iodine and chlorine, are applied sequentially and can be carried out before or after post-exposure. Furthermore, there is a need for a process for the immediate 2-halogen treatment of aqueous developed printing plates without the need for drying. According to the invention, it has a number average molecular weight of 20000-75000, its acrylonitrile content is 10-50% by weight and its carboxyl content is 0-15% by weight.
imagewise exposure with actinic radiation of a photosensitive elastomeric composition layer comprising a high molecular weight butadiene/acrylonitrile copolymer and a non-gaseous ethylenically unsaturated compound containing at least one terminal ethylene group; A method is provided for providing an improved solvent-resistant surface to a relief photosensitive flexographic printing plate, the relief areas of which have been created by liquid development of unexposed areas thereof, the method comprising: Optionally after drying the area in relief, in any order (1) post-exposure of the developed surface to a source of actinic radiation; and (2) sequentially exposing the developed surface to two aqueous halogen solutions. i.e. an aqueous solution with a contact time of about 15 seconds to 20 minutes with a free bromine concentration of 0.01 to 3.5% by weight or
Approximately 1.0-10 with a free iodine concentration of 0.2-10% by weight
The first, which is either an aqueous solution with contact with
contact with a second halogen solution for a contact time of about 15 seconds to 5 minutes of chlorine equivalents equivalent to that provided by an aqueous solution of halogen solution and 0.01 to 1.0 molar MaOCl and 0.012 to 1.2 molar HCl. It includes things. The photosensitive compositions used in the method of the invention include a high molecular weight butadiene/acrylonitrile copolymer, a non-gaseous ethylenically unsaturated compound, an organic radiation-sensitive free radical-generating photoinitiator or photoinitiator system and as discussed below. and other additives. The composition can be used in the form of a layer, or a layer of the composition can be adhered to a flexible support or a temporary support can be used. Useful flexible supports include plastic films and metal sheets, open or closed cell ohms, flexible rubber layers, or combinations of foam and rubber layers with plastic films. When a combination support is used, the plastic film is generally adjacent to the photosensitive layer. Examples of such supports include polymeric films such as polyethylene terephthalate, flame treated polyethylene terephthalate, electron discharge treated polyethylene terephthalate, polyimides such as those described in US Pat.
3179634 and others, and thin metal sheets such as aluminum, tinned steel (brushed or polished). The polymeric support generally has a thickness in the range of 0.001 inch to 0.007 inch (0.025 to 0.18 mm). The metal support generally has a thickness in the range of 0.010 to 0.0115 inches (0.25 to 0.29 mm) for aluminum and 0.008 to 0.010 inches (0.20 to 0.25 mm) for tinned steel. There is. Examples of foam supports include open and closed self-containing foams such as polyvinyl chloride, polyurethane, ethylene polyene diene rubber, neoprene, and the like. Examples of compressible rubber include styrene/
Examples include isoprene block copolymers, butadiene/acrylonitrile copolymers, natural rubber, and others. In their unexposed state, the photosensitive compositions disclosed herein are developable in aqueous, semi-aqueous basic or solvent solutions depending on the carboxyl content of the polymeric binder component of the photosensitive composition. This photosensitive layer is 0.005 to 0.250 inches (approximately 0.13 to 6.35 inches)
mm) or thicker. One essential component of the photosensitive elastomeric composition ranges from about 20,000 to about 75,000, preferably about
High molecular weight butadiene/acrylonitrile copolymer (a) having a number average molecular weight (n) ranging from 25,000 to about 50,000. Mn for the polymers described herein can be determined by gel permeation chromatography using polybutadiene standards.
The acrylonitrile content of this polymer ranges from about 10 to about 50
The weight percent varies preferably from about 15 to about 40%. Optionally, the copolymer also has a carboxyl content of 0 to about 15% by weight. If the copolymer contains carboxyl groups, the carboxyl content preferably ranges from about 1 to about 15% by weight, most preferably from about 2 to about 10% by weight. The copolymer is present in an amount of about 55 to 90% by weight, and preferably about 60 to about 75% by weight, based on the weight of the total composition. At least about 55% by weight copolymer is required to provide sufficient flexibility and physical integrity to the photosensitive element, particularly for flexographic plates. Carboxyl groups are incorporated into the high molecular weight copolymers by adding to the polymerization process a carboxyl-containing monomer, such as acrylic or methacrylic acid, or a monomer convertible to a carboxyl-containing group, such as maleic anhydride or methyl methacrylate. be able to. Such polymers are commercially available from several sources, such as from BF Goodrich Chemical Company under the tradename "Hycar". The other essential component of the photosensitive compositions of the invention is a non-gaseous ethylenically unsaturated compound (b) containing at least one terminal ethylenic group. The compound should be capable of forming high molecular weight polymers by free radical initiated chain extension addition polymerization and be compatible with the high molecular weight polymer (a). One group of suitable ethylenically unsaturated compounds includes unsaturated esters of alcohols, in particular α-methylene carboxyl groups and substituted α-methylene carboxylic acids and such esters, more particularly alkylene polyols and such esters of polyalkylene polyols. esters, and most especially 2~
Mention may be made of alkylene polyols and triacrylates and polyalkylene polyols di- and triacrylates made from alkylene polyols containing 15 carbon atoms or polyalkylene ether polyols or glycols containing from 1 to 10 ether bonds. The following specific compounds are other examples of this group. Tertiary butyl acrylate and methacrylate, 1,5-pentadiol diacrylate and dimethacrylate, N,N-diethylaminoethyl acrylate and methacrylate, ethylene glycol diacrylate and dimethacrylate, 1,4-butanediol diacrylate and dimethacrylate, Diethylene glycol diacrylate and dimethacrylate, hexamethylene glycol diacrylate and dimethacrylate, 1,3-propanediol diacrylate and dimethacrylate, decamethylene glycol diacrylate and dimethacrylate, 1,4-cyclohexanediol diacrylate and dimethacrylate, 2 , 2-dimethylolpropane diacrylate and dimethacrylate, glycerol diacrylate and dimethacrylate, tripropylene glycol diacrylate and dimethacrylate, glycerol triacrylate and trimethacrylate, trimethylolpropane triacrylate and trimethacrylate, pentaerythritol triacrylate and trimethacrylate. Methacrylate, Polyoxyethylated Trimethylolpropane Triacrylate and Trimethacrylate, and U.S. Pat.
Similar compounds disclosed in No. 3380831, 2,2-
Di(p-hydroxyphenyl)propane diacrylate, pentaerythritol tetraacrylate and tetramethacrylate, 2,2-di-
(p-hydroxyphenyl) propane dimethacrylate, triethylene glycol diacrylate, polyoxyethyl-2,2-di-(p-hydroxyphenyl) propane dimethacrylate, bisphenol A di(3-methacryloxy-2
-hydroxypropyl) ether, bisphenol A di(2-methacryloxyethyl) ether, bisphenol A di(3-acryloxy-2-hydroxypropyl) ether, bisphenol A di(2-acryloxyethyl) Ether, di(3-
Methacryloxy-2-hydroxypropyl) ether, di(2-methacryloxyethyl) ether of tetrachloro-bisphenol A, di(3-methacryloxy-2-hydroxypropyl) ether of tetrabromobisphenol A, tetrabromobis Di(2-methacryloxyethyl) ether of phenol A, di(3-methacryloxy-2-hydroxypropyl) ether of 1,4-butanediol, triethylene glycol dimethacrylate, polyoxypropyltrimethylolpropane triacrylate, butylene glycol diacrylate and dimethacrylate,
1,2,4-butanetriol triacrylate and trimethacrylate, 2,2,4-trimethyl-1,3-pentanediol diacrylate and dimethacrylate, 1-phenylethylene-1,2-dimethacrylate, diallyl fumarate , styrene, 1,4-benzenediol dimethacrylate, 1,4-diisopropenylbenzene and 1,3,5-triisopropenylbenzene. Aromatic polyhydroxy compounds such as bisphenols, novolaks and similar compounds such as U.S. Pat. No. 3,661,576, incorporated herein by reference.
Also useful are diacrylate and dimethacrylate esters of diepoxy polyethers, such as bisacrylates and methacrylates of polyethylene glycols having molecular weights from 200 to 500, and others derived from those described in the present specification. Other groups of suitable ethylenically unsaturated compounds include the compounds disclosed in U.S. Pat. No. 2,927,022, which is hereby incorporated by reference; for example, a plurality of addition-polymerizable ethylene bonds, especially when present as terminal bonds; and especially double bonds in which at least one and preferably most of such bonds include carbon-carbon double bonds and double bonds of carbon with heteroatoms (e.g. nitrogen, oxygen and sulfur). Examples include those conjugated with carbon. Preferred are those in which an ethylenically unsaturated group, especially a vinylidene group, is conjugated with an ester or amide structure. Particular examples of such compounds include unsaturated amides, especially amides of α-methylelcarboxylic acid and especially α,ω-diamines and oxygen-interrupted ω-diamines, such as methylenebisacrylamide, methylenebismethacrylamide, ethylenebismethacrylamide, 1, 6-hexamethylene bis-acrylamide, diethylenetriamine tris-methacrylamide, bis(methacrylamidopropoxy)ethane, β-methacrylamidoethyl methacrylate, N-(β-hydroxyethyl)-β-(methacrylamido)ethyl acrylate, and N,N -bis(β-methacryloxyethyl)acrylamide, vinyl esters such as divinyl succinate, divinyl adipate,
divinyl phthalate, divinyl terephthalate,
divinylbenzene-1,3-disulfonate, and divinylbutane-1,4-disulfonate,
Examples include diallyl fumarate and others. Other ethylenically unsaturated compounds that may be used include styrene and its derivatives, 1,4-diisopropenylbenzene, 1,3,5-triisopropenylbenzene, adducts of itaconic anhydride with hydroxyethyl acrylate ( adducts)
(1:1), adducts of itaconic anhydride and liquid butadiene/acrylonitrile polymers containing terminal amino groups, and itaconic anhydride with diacrylate and dimethacrylate esters of diepoxy polyethers, US Pat. No. 3,661,576 Mention may be made of the adducts described herein, polybutadiene and butadiene/acrylonitrile copolymers containing terminal and pendant vinyl groups, and unsaturated aldehydes such as sorbaldehyde (2,4-hexadienal). When aqueous basic developable systems are involved, water-bathable or ethylenically unsaturated compounds containing carboxyl or other alkali-reactive groups are particularly suitable. Additionally, the polymerizable ethylenically unsaturated polymers of US Pat. Nos. 3,043,805 and 2,929,710 and similar materials may be used alone or in admixture with other materials. Also useful are acrylic and methacrylic esters of ethylene oxide and adducts of polyhydric hydroxy compounds, such as those described in US Pat. No. 3,380,831. Optical crosslinking polymers disclosed in US Pat. Nos. 3,418,295 and 3,448,089 may also be used. All of these US patents are incorporated herein by reference. The amount of unsaturated compound added should range from about 2 to about 40% by weight, based on the total weight of the composition. The specific amount for optimal results will vary depending on the particular polymer used. Preferably the amount of unsaturated compounds ranges from about 5% to about 25% by weight. The ethylenically unsaturated compound preferably has a boiling point of about 100° C. or higher at normal pressures. The most preferred ethylenically unsaturated compounds are triethylene glycol diacrylate, triethylene glycol dimethacrylate, hexamethylene glycol dimethacrylate and hexamethylene glycol diacrylate. The photosensitive compositions of the present invention do not substantially scatter actinic radiation when in the form of a thin layer as described above. In order to ensure a substantially transparent mixture, i.e. a non-radiative scattering mixture, the butadiene copolymer and polymer components should and are preferably compatible with the ethylenically unsaturated compound in the proportions used. should be soluble in this. "Compatibility" refers to the ability of two or more components to remain dispersed without causing significant amounts of actinic radiation scattering from each other. Compatibility is often limited by the relative proportions of ingredients, and incompatibility is limited by haze in the photosensitive composition.
This is evidenced by the formation of Some slight haze can be tolerated from such compositions before or during exposure in the production of printed reliefs. However, if fine details are desired, haze should be completely excluded. The amount of ethylenically unsaturated compound, or any other ingredients used, is therefore limited to concentrations that do not produce undesirable light scattering or clouding. Another essential component of the photosensitive compositions of the invention is an organic radiation-sensitive free radical-generating initiator or initiator system (c). Virtually any organic radiation-sensitive free radical-generating initiator system that initiates and does not unduly terminate the polymerization of unsaturated compounds can be used in the photosensitive compositions of the present invention. In this specification, the expression "organic" means:
It is used to refer to compounds containing carbon and one or more of oxygen, hydrogen, nitrogen, sulfur and halogens, but no metals. Process transparencies used in imagewise exposure transfer heat generated from conventional sources of actinic radiation, and since photosensitive compositions are typically manufactured under conditions that produce high temperature results, free radical generation is preferred. The initiator compound is thermally inert below 85°C, and more preferably below 185°C. They should be dispersible in the composition to the extent necessary to initiate the desired polymerization or cross-linking under the influence of the amount of radiation absorbed in a relatively short exposure. These initiators are useful in amounts of from about 0.001 to about 10% by weight, and preferably from about 0.1 to about 5% by weight, based on the total weight of the solvent-free photosensitive composition. This free radical-generating initiator system has a
absorbs radiation in the range of 8000 Å, and about 2500 to ca.
It has at least one component having an actinic radiation absorption band with a molecular extinction coefficient of at least about 50 in the range of 8000 Å and preferably from about 2500 to about 5000 Å. By "actinic radiation absorption band" is meant a band of radiation active to generate the free radicals necessary to initiate polymerization or cross-linking of unsaturated materials. A free radical-generating initiator system may include one or more compounds that directly provide free radicals when activated by radiation. It may also include multiple compounds, one of which generates free radicals after doing so with a radiation-activated sensitizer. A large number of such free radical-generating compounds can be used in the practice of this invention, including aromatic ketones such as benzophenone, Michler's ketone, [4,4'-bis(dimethylamino)benzophenone] ], 4,4'-bis(diethylamino)benzophenone, 4-acryloxy-4'-dimethylaminobenzophenone, 4-
Acryloxy-4'-diethylaminobenzophenone, 4-methoxy-4'-dimethylaminobenzophenone, 2-phenyl-2,2-dimethoxyacetophenone (2,2-dimethoxy-1,2-diphenyletha) non), 2-ethylanthraquinone,
Phenanthraquinone, 2-tertiary butylanthraquinone, 1,2-benzanthraquinone, 2,3
-Benzanthraquinone, 2,3-dichloronaphthoquinone, benzyl dimethyl acetal and other aromatic ketones, benzoin, benzoin ethers such as benzoin methyl ether, benzoin ethyl ether, benzoin isobutyl ether and benzoin phenyl ether, methylbenzoin, ethylbenzoin and others benzoin and 2,4,5-triarylimidazolyl dimers such as 2-(o-chlorophenyl)
-4,5-diphenylimidazolyl dimer, 2-
(o-chlorophenyl-4,5-di(m-methoxyphenyl)imidazolyl dimer, 2-(o-fluorophenyl)-4,5-diphenylimidazolyl dimer, 2-(o-methoxyphenyl) Enil) -
4,5-diphenylimidazoyl dimer, 2-
(p-methoxyphenyl)-4,5-diphenylimidazolyl dimer, 2,4-di(p-methoxyphenyl)-5-phenylimidazolyl dimer,
2-(2,4-dimethoxyphenyl)-4,5-
Diphenylimidazolyl dimer, 2-(p-methylmercaptophenyl)-4,5-diphenylimidazolyl monomer, and other U.S. Patent No. 3479185
No. 3784557 and British Patent No. 997396
No. 1047569 and each specification of the same No. 1047569. These patents are incorporated herein by reference. The imidazolyl dimer can be used with free radical-generating electron donors such as 2-mercaptobenzisoxazole, leucocrystal violet or tri(4-diethylamino-2-methylphenyl)methane. Sensitizers such as Michler's ketones can be added. Various energy transfer dyes such as Rose Bengal and Eosin Y may also be used. Other examples of suitable disclosing agents are disclosed in US Pat. No. 2,760,863, which is incorporated herein by reference. The photosensitive composition may also have a small amount, e.g.
2.0% by weight of a thermal addition polymerization inhibitor can be included. Suitable inhibitors include hydroquinone and alkyl and aryl substituted hydroquinones;
2,6-ditertiary-butyl-4-methylphenol, p-methoxyphenol, tertiary-butylpyrocatechol, pyrogallol, β-naphthol,
2,6-ditert-butyl-p-cresol, phenothiazine, pyridine, nitrobenzene, dinitrobenzene, and the nitrosodimer inhibitor system described in U.S. Pat. No. 4,168,982, incorporated herein by reference. can give. Other useful inhibitors include p-torquinone, chloranil and thiazine dyes such as thionin blue G.
(CI52025), methylene blue B (CI52015) and toluidine blue (CI52040). Such photosensitive compositions can be photopolymerized or photocrosslinked without removing the inhibitor. A preferred inhibitor is 2,6-di-tert-butyl-
4-methylphenol and p-methoxyphenol. The oxygen and ozone resistance of the photosensitive compositions of the invention and of the printed reliefs produced therefrom can be improved by incorporating appropriate amounts of compatible, well-known antioxidants and/or antiozonants. Antioxidants useful in this invention include alkylated phenols such as 2,6-di-tert-butyl-4
-Methylphenol, alkylated bisphenols such as 2,2-methylenebis-(4-methyl-6
-tertiary butylphenol), 1,3,5-trimethyl-2,4,6-tris(3,5-ditertiary-butyl-4-hydroxybenzyl)benzene, 2
-(4-hydroxy-3,5-ditertiarybutylanilino)-4,6-bis(n-octylthio)-
Mention may be made of 1,3,5-triazine, polymerized trimethylhydroquinone and dilaurylthiopropionate. Antiozonants useful in the present invention include microcrystalline and paraffin waxes, dibutylthiourea, 1,1,3,3-tetramethyl-2-thiourea, and antiozonant AFD (product of Nafton). , norbornene such as di-5-norbornene-2-methyl adipate, di-5-norbornene-2-methyl terephthalate, Ozone Protector 80 (a product of Reichhold Chemical Co.), N-phenyl-2-naphthylamine, unsaturated vegetable oils such as rapeseed oil. , linseed oil, safflower oil, polymers and resins such as ethylene/vinyl acetate copolymer resins, chlorinated polyethylene, chlorosulfonated polyethylene, chlorinated ethylene/methacrylic acid copolymers, polyurethanes, polypentadiene, polybutadiene, furfural Examples include derivative resins, ethylene/propylene/diene rubbers, diethylene glycol esters of rosin, and α-methylstyrene/vinyltoluene copolymers. The ozone resistance of the printed relief produced can also be improved by annealing it at high temperatures before use. Optionally, an immiscible polymeric or non-polymeric organic or inorganic filler or reinforcing agent that is substantially transparent at the wavelength used for exposing the photosensitizer and that does not scatter actinic radiation, such as polystyrene, The photosensitive compositions may contain organophilic silica, bentonite, silica, powdered glass, colloidal carbon, and various types of dyes and pigments. Such materials are used in varying amounts depending on the desired properties of the elastomer. Fillers are useful in improving the strength of the elastomer layer, reducing tack, and even as colorants. The photosensitive composition preferably contains a compatible plasticizer to lower the glass transition temperature of the binder and to facilitate selective development. The plasticizer can be any common plasticizer that is compatible with the polymeric binder. Among the common plasticizers are dialkyl phthalates, alkyl phosphates, polyethylene glycols, polyethylene glycol esters and polyethylene glycol ethers.
Other useful plasticizers include oleic acid, lauric acid, and others. Polyesters such as polyethylene sebacate and others are preferred plasticizers. Plasticizers are generally present in an amount of 1 to 15% by weight, based on the total solids weight of the photosensitive composition. The photosensitive compositions of the present invention may be prepared in any suitable manner to contain each of the components: (a) a high molecular weight butadiene/acrylonitrile copolymer, (b) a compatible ethylenically unsaturated compound, and (c) a free radical-generating initiator. It can be manufactured by mixing systems. For example, flowable compositions may contain these and other desired additives in any order and optionally solvents such as chlorinated hydrocarbons such as methylene chloride, chloroform, methylchloroform, chlorobenzene, trichloroethylene, tetrachloroethylene and chlorotoluene, ketones such as methyl ethyl ketone, It can be prepared by mixing diethyl ketone and methyl isobutyl ketone with the aid of aromatic hydrocarbons such as benzene, toluene and xylene and tetrahydrofuran. The solvent may contain as diluent acetone, low molecular weight alcohols such as methyl, ethyl and propyl alcohol and esters such as methyl acetate, ethyl acetate and propyl acetate. This solvent can later be removed by heating the mixture or extrusion layer. Conventional milling, mixing and solution techniques can be used in the manufacture of these compositions. Specific techniques will vary due to differences in the properties of each component. The homogeneous substantially non-radiative scattering composition is formed into layers or sheets in any desired manner. For example, solvent casting, hot pressing, calendering or extrusion are suitable methods for producing layers of desired thickness. The photosensitive elements of the present invention can be in the form of a photosensitive layer or self-supporting sheet on a suitable forming wheel, belt or platen by solvent casting or extrusion, calendering or hot pressing of the photosensitive composition. . This layer or sheet can then be laminated onto the flexible support surface, and it can be adhered with the adhesive blend described below. If a solution is used, the coating can be formed on the adhesive-containing support. The thickness of the photosensitive layer formed is a direct function of the thickness desired in the relief image, and this depends on the subject matter to be reproduced and the final use of the relief. For example, thick soft relief is useful for flexographic printing, and thin hard relief is useful for lithographic printing. Generally, the thickness of the photosensitive layer is about 0.250 inch or less. For example, it varies from about 0.005 to about 0.250 inches (0.13 to 0.635 cm) and layers in this thickness range are used for the majority of printing plates. Between said photosensitive layer and the flexible support there is preferably a layer of an adhesive blend comprising at least two polymers selected from the following four polymer groups: do. (1) Polyester resin. A condensation polymer of ethylene glycol, terphthalic acid, isophthalic acid and azelaic acid in a molar ratio of about 6:2:1:3.
It has an n of 19,000 and a w of 37,000. (2) Polyester polyurethane resin. in methyl ethyl ketone at 15% solids by weight and using a Bruckfield spindle #3 at 12 rpm.
It is a crystalline thermoplastic resin with a Bruckfield viscosity of 100-1200 centipoise and an adhesive activation temperature in the range of 54-53°C. This polyester polyurethane resin has a yield point elongation of 15%,
615% elongation at break, 600psi (42.18Kg/cm ² )
It has a 400% elongation modulus and a crystallinity loss temperature of approximately 49°C. (3) Polyamide resin. Translucent bright amber color.
Ball and ring at 132-145℃
Softening point, melt viscosity of 40-60 poise at 210°C, 299
ignition point above ℃, 0.7% in 1 day and 1.6 in 7 days
% water absorption, tensile strength at yield of 460 psi (32.34 Kg/cm ² ), tensile strength at break of 450 psi (31.64 Kg/cm ² ) and elongation of 560% (tensile strength at yield, tensile strength at wave break) and the elongation is
Measured at 24°C according to ASTM method D-1708. ) (4) Polyamide resin. Translucent bright amber color.
Ring and ball softening point of 150-160°C, viscosity of 28-38 poise at 210°C, water absorption of 1.5% in 1 day and 2.8% in 7 days, and

[Table] (Tensile yield, tensile breakage and elongation are
Measured according to ASTM method D-1708 at the indicated temperatures. ) The number average molecular weight (n) of the resin can be determined by gel permeation chromatography (GPC) using known standards such as polybutadiene, which are known to those skilled in the art. Weight average molecular weight of resin (
w) can be determined by the use of light scattering techniques using known standards such as polystyrene, polymethacrylic acid, polymethyl methacrylate, etc., in a manner known to those skilled in the art. This particular polymer may be present in the following ranges based on the total weight of resin in the adhesive composition: (1) 0-78% by weight; (2) 0-78% by weight; (3) 0-94% by weight; 4) 0.97% by weight, which can be present in the adhesive blend. Preferred adhesive blends containing four, three and two resin components are described below, where percentages are based on the weight of all resin components. The percentage ranges for the four-component adhesive blend are as follows: (1) 25-31% by weight, preferably 25%, (2) 25-31% by weight, preferably 25%, (3) 25-19% by weight, preferably 25%, and (4) 25-19% by weight. %, preferably 25%. The percentage ranges for the two three-component adhesive blends A and B are as follows: A (1) 1 to 78% by weight, preferably 1 to 65%, (2) 1 to 78% by weight, preferably 1 to 65%, (3) 1 to 94% by weight, preferably 1 to 90%. B (1) 1 to 63% by weight, preferably 1 to 45%, (3) 1 to 93% by weight, preferably 1 to 85%, (4) 1 to 97% by weight, preferably 1 to 90%. The percentage ranges for the five two-component adhesive blends C-G are as follows: C. adhesive blends are particularly preferred. C (1) 7-77%, preferably 15-30% most preferably 30% and (3) 93-23%, preferably 85-50% most preferably 70%. D (1) 3-60%, more preferably 5-30% and (4) 97-40%, more preferably 95-70%. E (1) 23-77%, more preferably 35-45% and (2) 77-23%, more preferably 65-55%. F (2) 10-60%, preferably 25-30% and (4) 90-40%, preferably 75-70%. G (2) 7-72%, preferably 15-50% and (3) 93-28%, preferably 85-50%. The adhesive blend of the present invention has at least 3 lbs.
inch (53.57Kg/m), and generally e.g.
Provides greater adhesive support/photosensitive layer adhesion values in the range of pounds per inch (142.86 Kg/m) or more. These adhesion values are sufficient if the elements of the invention are used as printing plates, especially flexographic printing plates. The adhesive blend preferably contains additives such as blocking inhibitors, colorants such as dyes, and the like. Useful block formation inhibitors preferably include polyolefin particles or beads or other hard particles or beads such as silicon dioxide and the like. The surfactant dioctyl sodium sulfosuccinate may be used. Preferred polyolefin materials are described in the Examples.
The bead size of the blocking inhibitor can be larger than the thickness of the adhesive layer. As a result, the beads partially protrude outside the layer of adhesive blend. It is believed that such a structure has little or no effect on the degree of adhesion. Many types of colorants or dyes are also useful in the adhesive layer. The preferred dye is Dupont Milling Blue BL (CI Acid Blue).
59). Other useful dyes include methylene violet (CI Basic Violet 5), "Laxol" Fast Blue MBSN (CI Solvent Blue 38), and "Pontasil" Wool Blue.
BL (CI Assisted Blue 59 or CI 50315), "Pontashiur" Wool Blue GL (CI Assisted Blue
102 or CI 50320), Victoria Be Your Blue
BO (CI Basic Blue 7 or CI 42595), CI
109 Red dye, Rhodamine 3 GO (CI Basic Cred 4), Rhodamine 6 GDN (CI Basic Cred 1 or CI 45160), Fuchsin dye (CI
42510), Calcoside Green S (CI 44090) and Anthraquinone Blue 2GA (CI Acid Blue 58). The adhesive solution is generally prepared by adding the components (i.e., polymer, polyolefin block inhibitor, colorant) to the solvent in the following order with continuous stirring. Useful solvents include mixtures such as methylene chloride/ethyl acetate, methylene chloride/n-butyl acetate, methylene chloride/
Examples include cyclohexanone, methylene chloride/methanol/cellosolve, etc., and preferably a methylene chloride/cellosolve (90/10 parts) mixture. Additional solvent can be added to compensate for any weight loss. The choice of solvent will help ensure that the coating does not blister.
and is governed by the desire to provide the fastest practical drying rates without leaving small amounts of solvent behind. The solvent should also have a solubilizing effect on the dye present. The adhesive solution is then applied to the flexible support by known means, e.g. using a doctor blade or coated in a commercially available continuous web coater dryer to a coating thickness of about 80 to 500
mg/dm ² , preferably in the range of about 260 to 300 mg/dm ² . The most preferred coating weight of the adhesive layer is approximately 260 mg/dm ²
It is. Generally, the adhesive has a dry thickness of 0.0008 to 0.001 inch (0.020 to 0.025 mm). For continuous coating the web speed is e.g.
~150 ft/min (4.57-45.72 m/min). Drying temperature is 60-130℃, preferably 80℃
In the range of ~90℃. A preferred flexible support is flame treated polyethylene terephthalate having a thickness of 0.001 to 0.007 inches (0.025 to 0.18 mm), preferably 0.005 inches (0.13 mm). Flame treatment of polymeric films is known. No. 3,145,242, US Pat. No. 3,360,029, and US Pat. No. 3,360,029, incorporated herein by reference.
No. 3,391,912 describes methods and apparatus useful for flame treating polymeric films. The fuel equivalence ratio φ of the combustion gas mixture is 1.4, which is 5
Equal to (propane flow rate) / [(oxygen flow rate) + (0.21 air flow rate)]. All flow rates are standard cubic feet or minutes. Web speed is 175 linear feet/min (53.34 m/min). The dried adhesive coated support can be adhered immediately to the photosensitive layer or can be saved for subsequent adhesion. To form the photosensitive element, the adhesive-coated support is pressed onto the photosensitive layer at e.g. 20,000-30,000 psi (1406
Lamination can be carried out at a pressure of ~2109 Kg/cm ² for up to about 3 minutes, followed by cooling in a press to below 60°C. Preferably the photosensitive element is produced by calendering. The photosensitive layer of the element, preferably made by extrusion through a die, has a 0.005 inch (0.13 mm) thick polyethylene terephthalate film disposed away from the side adjacent to the adhesive layer, which is hereafter referred to as a protective cover. Acts as a sheet. Other films such as polystyrene, polyethylene, polypropylene or other releasable materials may be used. Preferably, between the photosensitive layer and the film cover sheet there is present a thin, rigid, flexible, solvent-soluble layer, such as a flexible polymeric film or layer, such as polyamide or a copolymer of ethylene and vinyl acetate. A flexible polymeric film remains on the photosensitive layer after removal of the film cover sheet. The flexible polymeric film protects the overlying image-containing negative or transparency for reuse or improves contact or alignment with light-sensitive surfaces. Prior to imagewise exposure using the light source described below, the photosensitive element is exposed through the support to polymerize a predetermined thickness of the photosensitive layer adjacent the adhesive support. This polymerized portion of the photosensitive layer is called the floor. Floor thickness varies depending on exposure time, exposure source, etc.
This exposure is generally for 1 to 30 minutes. In accordance with the present invention, selected portions of the photosensitive layer of said element may be formed, for example, in a process transparency, i.e., a portion of optical density substantially transparent to actinic radiation and of substantially uniform optical density, and a portion opaque to actinic radiation and Printed reliefs can be produced by exposure through an image-containing transparency or stencil having areas of substantially uniform optical density until substantial addition polymerization or optical cross-linking occurs. During addition polymerization or crosslink formation, the butadiene/acrylonitrile copolymer/ethylenically unsaturated compound composition is converted to an insoluble state in the radiation-exposed portions of the layer and no significant polymerization or crosslinking occurs in the unexposed portions or areas of the layer. No binding occurs. The unexposed portions of the layer are removed with a liquid developer for high molecular weight butadiene/acrylonitrile copolymers. Actinic radiation from any light source of any type may be used in the photopolymerization process. The radiation may originate from a point source or may be in the form of parallel rays or diverging beams. By using a broad radiation source relatively close to the image-containing transparency, radiation passing through the transparent portion of the transparency enters as a diverging ray and continues through the diverging portion in the light-sensitive layer below the transparent portion of the transparency. irradiate the target. This results in a ie trapezoidal polymer relief with its greatest width at the bottom of the photosensitive layer. The upper surface of this relief is the dimension of the transparent part. As long as the free radical-generating initiator system activatable by actinic radiation exhibits its maximum sensitivity in the ultraviolet range, the radiation source is preferably between about 2500 Å and 5000 Å.
should provide an effective amount of radiation having a wavelength range of . Suitable such radiation sources include, in addition to sunlight, carbon arcs, mercury vapor arcs, fluorescent lamps with ultraviolet emitting phosphors, argon glow lamps, electronic flash units and photographic flood lamps. Electron accelerators and electron beam sources via suitable masks may also be used. Among these, mercury vapor lamps, especially the sunlamp or "blacklight" type and fluorescent sunlamps are most suitable. The radiation exposure time can vary from a fraction of a second to several minutes depending on the intensity and spectral energy distribution of the radiation, its distance from the composition and the nature and amount of the composition available. Typically, a mercury vapor arc, solar lamp, or high ultraviolet output fluorescent tube is used at a distance of about 1.5 to about 60 inches (3.8 cm to 152 cm) from the photosensitive composition. The exposure temperature is not particularly critical, but it is preferred to operate at about room temperature to slightly higher temperatures, ie, from about 20 DEG to about 35 DEG C. After imagewise exposure, the image can be developed by washing with a suitable developer. The developer has a good solvent or swelling effect on the butadiene/acrylonitrile copolymer/ethylenically unsaturated compound composition and, during the required period of time, of the unpolymerized or uncrosslinked parts, the insolubilized image or The support or adhesive layer should have little effect. The developer preferably also removes the polymer film layer, if present.
Suitable developers include organic solvents such as 2-butanone, benzene, toluene, xylene, trichloroethane, trichloroethylene, methylchloroform, tetrachloroethylene and solvent mixtures such as tetrachloroethylene/n-butanol and others. When the high molecular weight butadiene/acrylonitrile copolymer component contains carboxyl groups, suitable solvents include aqueous bases, which may be supplemented with water-soluble organic solvents. Suitable specific developer mixtures include sodium hydroxide/isopropyl alcohol/water, sodium carbonate/water, sodium carbonate/2-butoxyethanol/water, sodium borate/2-butoxyethanol/water, sodium silicate/2-butoxy Ethanol/glycerol/water, sodium carbonate/
2-(2-butoxyethoxy)ethanol/water,
and sodium hydroxide (0.5% by weight) in 2-(2-butoxyethoxy)ethanol, 16.6% by volume in water. This is preferred. The particular developer combination chosen will depend on the carboxyl content of the photosensitive composition and the nature and amount of binder used. Other aqueous developer combinations that may be used are described in U.S. Pat.
It is described in the specification of No. 3796602. These aqueous base/water-soluble organic solvent combinations may be preferred in some cases because of their low cost, nonflammability, and low toxicity. Development may be carried out at about 25°C, but sometimes the best results are obtained when the temperature of the solvent is between 30° and 60°C. Development time is 1 to 120 minutes, preferably 1 to 120 minutes.
It can be in the range of 25 minutes. In the development step in which the relief is formed, the developer solution can be applied in any convenient manner such as pouring, impregnating,
It can be applied by spray or roller application. Brushing helps remove unpolymerized or uncrosslinked portions of the composition. When a printing plate is aqueous developed, for example, an aqueous solution for about 5 to 300 seconds is then applied to the developer plate to remove any traces of developer from the surface of the plate.
The expression "aqueous development" includes washing with water. After solvent development, the printing plate is heated to room temperature to approximately 125°C.
Dry for 1 hour at a temperature preferably in the range of 60°C. The printing plate may be dried after aqueous development, but the washed aqueous developer plate can be contacted with an aqueous bromine- or iodine-containing solution while still wet. Optional hot air drying can be accomplished through the use of a forced hot air dryer or other suitable dryer. The plates are first injected into an aqueous solution with a free bromine concentration of 0.01-3.5% by weight and a PH of 0.7-8.7.
seconds to 20 minutes, or about 1.0 to 10 minutes to an aqueous solution having a free iodine concentration of 0.2 to 10% by weight. After either of these halogen treatments e.g. 0.001-1.0 molar NaOCl and 0.012-
by a solution with a free chlorine concentration equal to that provided by an aqueous solution of 1.2 molar HCl.
Perform chlorine treatment for 15 seconds to 5 minutes. The plate can be flooded with an aqueous bromine solution or immersed in a bromine solution, the latter being preferred. It is preferred to keep the bromine solution in contact with the printing plate for 15 seconds to 20 minutes, more preferably 30 seconds to 5 minutes. The bromine solution is preferably used at ambient temperature, but it can be heated to about 35°C. This bromine-containing solution is (1)
Bromine, (2) bromate-bromide-system (bromate and bromide are salts of alkali metals, preferably sodium or potassium, and acids are hydrochloric acid, hydrobromic acid, sulfamic acid or other strong protic acids) (3) For example, German Patent No. 2823300
the bromine-containing complex described in the specification, or
(4) Monopersulfate-bromide systems in which the monopersulfate and bromide are salts of alkali metals, preferably sodium or potassium, and as described in U.S. Patent Application No. 375,975, herein incorporated by reference. (disclosed) to water. Preferably, the bromine-containing solution may be prepared by adding 20 ml of concentrated HCl to 1800 ml of tap water while mixing. While mixing in this solution,
200ml tap water, 10g potassium bromide and 2.8g
Add a mixture of potassium bromate (90.56%
_H2O /8.81% HCl/0.49% KBr and 0.14%
_KBrO3 ). Free bromine concentration is 0.4%. Instead of an aqueous bromine solution, the printing plate can be flooded with or immersed in an aqueous iodine solution. The latter is preferred. Preferably the iodine solution is held in contact with the printing plate for 1.5 to 2.5 minutes. Iodine solutions are preferably used at ambient temperature, but they can be heated to about 35°C. Preferably the iodine-containing solution contains e.g. 6.4 g potassium iodide and e.g. 12.7 g
It can be prepared by adding 200ml of iodine to 200ml of water. After carrying out one of the aforementioned halogen treatments, the printing plate can be flooded or immersed in an aqueous chlorine solution. Preferably, the chlorine solution is held in contact with the printing plate for 0.5 to 1.0 minutes. The chlorine solution is preferably used at ambient temperature, but it can be heated to about 35°C. The chlorine-containing solution is 90 ml of "Clorox".
)' and 10ml of concentrated i.e. 39% hydrochloric acid to 900ml of water
It can be produced by adding to ml. After imagewise exposure and development, the printing plate can be post-exposed to a source of actinic radiation either before or after said halogen treatment. Post-exposure generally preferably lasts from 5 to 15 minutes to the actinic radiation source used for imagewise exposure. After both treatments, the printing plate is ready for use. A preferred embodiment is illustrated in Example 1. Printed reliefs produced from the light-sensitive flexographic elements of the invention can be used for all types of printing, but only those where a distinct height difference between the printed and non-printed parts is required. and especially for flexographic printing where elastic printed parts are required for example for printing on deformable printing surfaces. These types include, for example, dry offset printing, where the ink is carried by the raised areas of the relief, as in conventional letterpress printing, which requires a greater height difference between printed and non-printed areas. and those in which the ink is carried by recesses in the relief, as in intaglio printing, for example in line and inverted halftones. This plate is particularly useful for multicolor printing. The resulting relief and printed images exhibit fidelity to the original transparency in both minute detail and overall dimension even when the elements are imagewise exposed on a cylindrical support. The relief is tough and abrasion resistant with high impact strength and has broad ink compatibility and improved solvent resistance. The following example illustrates the invention, but where parts and %
is based on weight. The following tests are useful in evaluating printing plates. Tackiness Test The exposure and development printing plate of the present invention can be tested for its tackiness as follows. (1) Clean the surface with isopropanol. (2) For example, use Scotto Brand 510 toilet tissue on the plate surface (1 inch x 2 inches, 2.54 cm x 5.08 cm) using a 500 g weight.
cm) for 30 seconds. (3) Remove the tissue and record the results according to the following criteria. (A) No tack - no stickiness (B) Slight tack - sticks but peels off from the surface (C) Sticky - peels off but leaves a few fibers on the plate (D) Very tack - sticks A person skilled in the art can fix a non-adhesive or Grade (A) printing plate surface by touch, i.e., by finger-touching. Both methods have been used. All processed samples below are without tack. Ink/Solvent Compatibility Testing The following method is used to determine the compatibility and usefulness of printing inks and solvents for flexographic printing plates having a photosensitive elastic composition layer as described herein. After measuring the flat exposed and developed printing plate for its thickness, shore A hardness (ANSI/ASTM D 2240-75) and weight, it is immersed in a specific solvent or ink for 24 hours. After removal from the solvent or ink and pat dry with a cotton ball, its thickness, Shore A hardness and weight are determined. If raw data representing thickness change (△T), shore A hardness change (△H) and weight change (△%W) in inches (mm) meets all of the following standards: In this case, the printing plate is considered to be compatible (E) with respect to solvents and/or inks. △T _raw : 0.003 inches (0.076 mm) △H _raw : -5 shore A unit △%W _raw : 3.5% Printing plates are free of solvent and and/or considered incompatible or unsatisfactory (U) with respect to the ink. △T _raw : 0.012 inches (0.305 mm) △H _raw : -20 shore A units △%W _raw : 7.0% In the range intermediate between the above two standards, treated printing plates can be used in various ways with respect to solvents and/or inks. Intermediate() is of usefulness. In addition to the above evaluations useful for single halogen treatments, these three physical measurements are combined into a single figure of merit, hereinafter referred to as "F". It is also desirable to do so. The F values for the separate individual treatments are then added together to give the expected F for the combination of treatments.
It is possible to give a heuristic prediction. F is obtained using the following equation. F=23.60−(0.152△T _raw −0.231△H _raw +0.4△%W _r
aw )/23.60 Numerical factors for various raw data are normalized factors derived from the performance of control plates without halogen treatment and tested in isopropanol/ethyl acetate (80/20 volume ratio) as described below. Weighting factors are then estimated by those skilled in the art to indicate the relative importance of the data in predicting print performance. The weighting factor (Wf) is as follows. 0.35 for ΔT ΔH 〃 0.25 Δ%W 〃 0.40 The normalization factor (nf) is obtained from the control plate data as follows.

[Table] Therefore, it is a numerical coefficient, that is, a product (wf) _i × (nf)
_i becomes as follows. For △T _raw 0.152 △H _raw 〃 −0.231 △%W _raw 〃 0.400 All data are on the same scale, that is, 0 to 1
In order to standardize to △H raw, the coefficient for △H _raw must be negative. The reason is that △H _raw is negative. △%W _ran for a constant in the expression of F
The selection of 23.60 reflects the conclusion that the Δ%W measurement is the most important of these three. An F value of 1.0 for a flexographic photopolymerizable printing plate represents a substantially perfect upper value for a superior plate. That is, solvent impregnation (soaking) produces no change in any of the three measured properties. Using the above formula for determining F, the above qualitative standard becomes: Excellent (E) = 0.88 to 1.0 Moderate (I) > = 0.62 to 0.88 Unsatisfactory (U) = 0.0 to 0.62, i.e. (1) the printing plate is more susceptible to attack by the chosen solvent or ( 2) If a stronger solvent is used in the compatibility test, F can take a negative value, i.e. 0.0. Furthermore
(3) Certain individual treatments or non-inventive combinations of treatments actually reduce the solvent tolerance of treated plates relative to that of untreated plates. For example, treatments i and j for solvents 2, 3 and 4 in Table 2 below
Please refer to the comparison with processing g. Compare the F values for samples 2 and 3, 8 and 9, and 14 and 15 in Table 8. For cases (1) and (2) above, F combination=F ₁ +F ₂ is expected. Again, the above (3) is F combination=F ₁ +
Predict (F ₂ −F untreated). These formulas are used below. Expected values are independent of processing order. In addition to simplifying the intercomparison of the results of various treatment combinations on flexographic printing plates exposed to various ink/solvent combinations, the F-value provides a Useful for predicting the number of good prints to be obtained in the prints used. The following correlation exists when both print run data and F-number are available. F Number of good prints 0.94 2000000 sheets 0.88 200000 sheets 0.69 5000 sheets The adhesive solution is prepared from the following ingredients.

[Table] The above polyamide resin (3) is "Macromelt" 6238 (a product of Henkel Adhesive), which is translucent and bright amber in color, with a ring and ball softening point of 132-145°C and a ring and ball softening point of 210°C. Melt viscosity of 40 to 60 poise, ignition point of 299℃ or higher, 0.7 in one day
% and 1.6% moisture absorption in 7 days, 460psi (32.34
Kg/cm ² ) tensile yield strength, 450psi (31.64Kg/
cm ² ) and an elongation of 560% (Tensile yield strength, tensile strength and elongation are measured at 24° C. according to ASTM method D-1708). The polyester resin is a reaction product of ethylene glycol, terephthalic acid, isophthalic acid and azelaic acid (in a molar ratio of 6:2:1:3);
It has an n of 19,000 and a w of 37,000. Polyolefin is known as ``Vesto''.
SF-616 (a product of Doula Commodities), is snow white in color, has a molecular weight of approximately 1600, a density of approximately 0.96 at 20℃, a penetration hardness of 0.5 to 1.0 at 25℃, and a It has a melting point of 118-128°C, a particle size such that about 85% are 10μ or less and about 15% are 10-20μ. The above ingredients are added in sequence to a methylene chloride/cellosolve (90/10) mixture to produce a solution of about 16% solids. Polyolefin beads do not dissolve. The mixture is continuously stirred during and after the addition of the ingredients to effect dissolution. Any weight loss during mixing is compensated by addition of methylene chloride. This adhesive solution is applied to the flame treated surface of a 0.005 inch (~0.13 mm) thick polyethylene terephthalate film support using a continuous web coater/dryer to produce a dry coating weight of about 260 mg/dm ² . The web speed is 45 ft/min (~13.72 m/min) and the drying temperature is 86°C (186.7°). The adhesive coated polyethylene terephthalate support is placed adhesive side up in a dammed steel platen 0.080 inch (2.03 mm) thick, the thickness of the finished printing plate. Place the adhesive-coated support and platen on a press and photopolymerize on a 0.005 inch (0.13 mm) thick polyethylene terephthalate cover sheet with a polyamide resin layer having a dry thickness of 0.00017 inch (0.004 mm). A 0.090 inch thick extruded sheet of the adhesive composition is placed thereon, cover sheet side up, and covered with a steel plate. A cover sheet with a polyamide layer is produced by coating a polyethylene terephthalate film using an extrusion die coater with the following solution: Ingredient amount (%) Methylene chloride 81.0 Methanol 2.0 N-methylpyrrolidone 10.0 Polyamide resin 7.0 The polyamide resin used here is "Macromelt" 6900 (product of Henkel Adhesive), with a ring and ball size of 266 to 302㎜. softening point,
Melt index of 5-15g/347/10〓, ignition point of 570〓, water absorption of 0.2% in 1 day and 0.5% in 7 days,
It has a tensile yield strength of 1200psi, a tensile breaking strength of 3500psi and an elongation of 540% (tensile yield strength, tensile breaking strength and elongation at 24℃
(Measured by ASTM D-1708 method). Blend the following ingredients and pass through the die 170
An extruded sheet of the photopolymerizable composition is produced by extrusion at <0>C.

Table: Increase temperature and apply pressure gradually.
This spreads the photopolymerizable sheet over the dammed portion of the platen. After uniformly dispersing the sheet, increase the temperature to 160℃ and 20000~30000psi
A pressure in the range (1406-2109 Kg/cm ² ) is applied and held for 3 minutes. The assembly is cooled in the press to below 60°C by flowing water through the press platen. The formed laminated element is removed from the press and placed support side up in an exposure unit. The element is given a general exposure through the support in air at atmospheric pressure for 4 minutes to polymerize the predetermined thickness of the photopolymerizable layer adjacent to the adhesive support. This overlapping portion of the element is called the floor. After removal of the cover sheet, the element was placed in a "Cyrel" exposure unit (manufactured by DuPont) equipped with a Sylvania BL-VHO-fluorescent lamp. The image-containing transparency (negative) and the element are exposed under vacuum for 15 minutes. The duration of exposure is a function of the polymer sheet length, the thickness of the polymeric floor, and the type of image-containing transparency used. Remove the exposed transparency and replace the exposure element with a rotary drum brush type "Shillel"
Place it in the 3040 processor. The unpolymerized portion of the element and the entire polyamide resin layer were washed in a processor for 15 minutes with 0.5% by weight sodium hydroxide in 16.6% 2-(2-butoxyethoxy)ethanol/water by volume followed by a 2-minute water rinse or with tetrachloroethylene/butanol. Remove by washing with (80/20) mixture. 0.035 inch (0.89
mm) relief image is obtained. Place the developer element (printing plate) in a forced hot air dryer or other suitable dryer and dry at 60°C for 15 minutes.
Let dry for a minute. In the examples below, the following halogen treatment solution is used. Bromine 20ml concentrated HCl in 1800ml tap water while mixing
Add. 200ml tap water while mixing into this solution,
Add 10 g potassium bromide and 2.8 g potassium bromate (free bromine concentration 0.4%). Iodine Add 6.4 g potassium iodide and 12.7 g iodine to 200 ml water. Chlorine 90ml Clorox and 10
Add ml of concentrated (37%) HCl to 900 ml of water (NaOCl ~ 0.06 molar and HCl ~ 0.12 molar). Example 1 Post-expose the above exposure-development flexographic printing plate for 10 minutes in air using the same exposure source as used for the imagewise exposure. The plates have a shore A2 hardness ranging from 56 to 60. The plates were halogenated (one control was not halogenated) as described below and exposed to various solvent mixtures and
Soak in 100% 2-propanol. The strength of the solvent is increased by adding more ethyl acetate to 2-propanol. The plate is tested for solvent resistance as described in Ink/Solvent Compatibility Testing. The raw data values obtained are listed in Table 1 below. The calculated F values are listed in Table 2 below. The symbols in the table are as follows. Solvent 1: 2-propanol 2: 2-propanol (95)/ethyl acetate (5) 3: 2-propanol (90)/ethyl acetate (10) 4: 2-propanol (85)/ethyl acetate ( 15) 〃 5: 2-propanol (80) / ethyl acetate (20) Treatment a: Br ₂ 10 minutes, Cl ₂ 0.5 minutes〃 b: Br ₂ 2 minutes, Cl ₂ 0.5 minutes〃 c: Br ₂ 10 minutes, Cl ₂ 0.5 minutes (calculated value) 〃 d: Br ₂ 2 minutes, Cl ₂ 0.5 minutes (calculated value) 〃 e: Br ₂ 10 minutes, no Cl _2〃 f: Br ₂ 2 minutes, no Cl _2〃 g: Br ₂ None, no Cl ₂ h: Cl ₂ 0.5 min, Br ₂ 10 min i: Cl ₂ 0.5 min, Br ₂ 2 min j: Cl ₂ 0.5 min, no Br ₂

【table】

【table】

【table】

[Table] As can be seen from the values in Table 2, the printing plates a and b treated according to the invention are particularly strong in solvents 1 to 5 compared to similar printing plates e to j treated by a process not according to the invention. It has excellent solvent resistance. This plate also outperforms calculated treatments e and d. In the very weak solvent 2-propanol, the calculated F values are essentially the same for the two halogen treatments in either order. The following Table 3 consists of the data in Table 2, i.e. the values of a, b, c, d, h and i for solvents 1 to 5, which represent the F during the halogen treatment of the present invention and the reverse order of treatment. It shows the difference in value.

TABLE The positive values observed in Table 3 for the differences between a-c and b-d indicate a superadditivity to the treatment of the present invention. The generally negative values observed in Table 3 for the differences in h-c and i-d indicate the inferior results obtained when chlorination precedes bromine treatment. Example 2 A flexographic printing plate was exposed, developed, post-exposed as described in Example 1 and halogen treated as described below.
into an n-butanol/n-propyl acetate (80/20) solution that is stronger than solvent 5. The plate is tested for solvent resistance as described in Ink/Solvent Compatibility Testing. The raw data values of ΔT, ΔH, and Δ%W obtained are used to calculate the F value, which is listed in Table 4. The symbols for this process are the same as those described in Example 1.

【table】

[Table] Ming excellence
F _b + F _i =1.04 〃
As can be seen from the foregoing data, the process of the present invention is superior to the results expected from the sum of the individual processes, and this is significantly better than the reverse order of processes. Example 3 A post-exposed flexographic printing plate as described in Example 1 is brominated for 4.5 minutes, then chlorinated for 30 seconds, washed with water and dried. The plate is mounted using double-sided adhesive tape onto the printing cylinder of a Gallus-Stanford model A160 printing press (manufactured by Feldruch-Maschinenfabrik Printers and Engineers). Polyethylene base material and n-propanol/n
- A 12-hour print run at 300 pages per minute using a propyl acetate (80/20) solvent-based ink (Clark Graphics product, Cyan Blue #SPX-10833, Batch 5279) totals approx.
Gives good quality prints for 200000 good prints. Control plates treated for 10 minutes in bromine only after approximately 10,000 impressions or less
Gives images of unsatisfactory quality after 30 minutes of printing time. Example 4 Other printing plates are prepared as described in Example 1, processed and tested as described in Ink/Solvent Compatibility Testing. As shown in Table 5 below, the post-exposure step described in Example 1 is carried out before, during or after the two halogen treatments. The solvent is Solvent 3 of Example 1, 2-propanol/ethyl acetate (90/10). Processing symbol a
~j are the same as described in Example 1. PE is post-exposure. Other symbols k to u are as follows. Treatment k: Br ₂ 0.25 min, Cl ₂ 0.25 min l: Br ₂ 0.50 min, Cl ₂ 0.50 min m: Br ₂ 0.50 min, PE, Cl ₂ 0.50 min n: Br ₂ 0.50 min, no Cl ₂ o: Br ₂ 0.25 min, PE, Cl ₂ 0.25 min〃 p: Br ₂ 0.25 min, no Cl _2〃 q: Cl ₂ 0.25 min, no Br _2〃 r: Br ₂ 10.0 min, PE, Cl ₂ 0.50 min〃 s: Br ₂ 10.0 min, Cl ₂ 0.50 min, PE 〃 t: Br ₂ 2.0 min, PE, Cl ₂ 0.50 min〃 u: Br ₂ 2.0 min, Cl ₂ 0.50 min, PE

【table】

Table: Samples 6, 13 and 14 show the variation in F value when changing the order of PE for bromine and chlorine treatments for 15 seconds. As shown in Table 6, post-exposure is more effective when performed first, but it is effective in either order.

Table: Samples 7.9 and 10 show the variation in F values when varying the PE order for bromine and chlorine treatments for 30 seconds. As shown in Table 7, there is little effect of varying PE order.

【table】

TABLE EXAMPLE 5 The printing plate prepared in Example 1 is halogen treated (iodine replaced by bromine) as described below, with the exception of one control without halogen treatment. After soaking in a solvent mixture of 2-propanol/ethyl acetate (90/10) for 24 hours and tapping dry, the solvent resistance of the printing plate was determined as described in the Ink/Solvent Compatibility Test above. test. The F value for each treatment is shown in Table 8.

【table】

Calculated from [Table]
18 16−17=△(measured value − 0.27, synergy − calculated value)
The results in Table 8 show that there is an improvement in the solvent tolerance of the plates when treated according to the present invention compared to the additive results of a single treatment. Processing 4-
The difference results for 5, 10-11 and 16-17 indicate that iodine treatment followed by chlorine treatment provides a synergistic improvement. Example 6 Printing plates prepared as described in Example 1 and halogenated by treatments a, b, r, s, t and u as described in Examples 1 and 4 were mixed with n-propanol/n-propyl acetate (80/ 20) to 24
Soak for an hour and evaluate as described above.
The results set forth in Table 9 below demonstrate that post-exposure following two-stage halogen treatment is significantly superior to post-exposure at other points in the processing process for printing plates impregnated with the aggressive solvent. Show that. The results of this example differ from those obtained in Example 4, which used a less aggressive solvent, 2-propanol/ethyl acetate (90/10), and a milder halogen treatment.

【table】

Claims (1)

[Scope of Claims] 1. High molecular weight butadiene/acrylonitrile copolymers having a number average molecular weight of 20,000 to 75,000, an acrylonitrile content of 10 to 50% by weight, and a carboxyl content of 0 to 15% by weight, and less. Formed by imagewise exposing a photosensitive elastomeric composition layer consisting of a non-gaseous ethylenically unsaturated compound containing one terminal ethylene group to actinic radiation and developing the unexposed portion with a liquid. After drying the relief part of the flexographic printing plate, if necessary, apply the following (1).
and (2) in any order, including (1) post-exposing the developed surface to a source of actinic radiation, and (2) exposing the developed surface first to the first halogen solution described below and then to the second halogen solution described below. Contact with a halogen solution In (2) above, as the first halogen solution, 0.01
When using an aqueous solution with a free bromine concentration of ~3.5% by weight, contact for approximately 15 seconds to 20 minutes or
When using an aqueous solution with a free iodine concentration of 0.2 to 10% by weight, contact for about 1.0 to 10 minutes and as a second halogen solution 0.01 to 1.0 molar aqueous solution.
An improved relief photosensitive flexographic printing plate consisting of contact for about 15 seconds to 5 minutes with a NaOCl solution and a solution having a free chlorine concentration equal to that given by an aqueous HCl solution of 0.012 to 1.2 molar. A method of imparting a solvent-resistant surface. 2. Contacting the printing plate first with an aqueous bromine solution and then with an aqueous chlorine solution
The method described in section. 3. Contacting the printing plate first with an aqueous iodine solution and then with an aqueous chlorine solution
The method described in section. 4. The method of claim 1, wherein the aqueous bromine solution is prepared by mixing bromine or an alkali bromate-bromide-acid mixture in water. 5. From bottom to top, the flexographic printing plate sequentially comprises (A) a flexible support, (B) based on the total weight of the composition: and its acrylonitrile content is 10~
50% by weight and carboxyl content is 0
~15% by weight of a high molecular weight butadiene/acrytonitrile copolymer; (b) 2 to 40% by weight of a high molecular weight butadiene/acrytonitrile copolymer capable of forming a high molecular weight polymer by free radical initiated chain extension addition polymerization; a compatible non-gaseous ethylenically unsaturated compound containing at least one terminal ethylene group; (c) 0.001 to 10% by weight of an organic radiation-sensitive free radical-generating system activatable by actinic radiation; and (d ) a photosensitive elastomeric composition layer consisting of 0 to 15% by weight of a compatible plasticizer, (C) a flexible polymeric film, (D) a removable cover sheet, and optionally layers (A) and 2. A method according to claim 1, wherein the photosensitive elastomer-like element constituted by the adhesive composition layer present between layers (B) is produced by imagewise exposure and liquid development. 6. The method of claim 1, wherein the developed surface is formed by aqueous development and the halogen treatment is carried out without drying the developed surface.