JPH0140970B2 - - Google Patents

Description

[Detailed description of the invention]

The present invention relates to a method for surface treatment of photosensitive flexographic printing plates. More specifically,
The present invention relates to the surface treatment of flexographic printing plates whose photosensitive layer contains a polymer of conjugated diolefin hydrocarbons. Even more particularly, the present invention relates to the surface treatment of photosensitive elastic layers containing polymers of conjugated diolefin hydrocarbons with bromine. Light-sensitive flexographic printing plates are becoming more important in the printing industry. Particularly useful compositions for the production of such flexographic printing plates include an addition-polymerizable ethylenically unsaturated compound, a photoinitiator, and a block copolymer such as styrene as a polymeric binder.
Mention may be made of compositions containing either butadiene-styrene and styrene-isoprene-styrene polymers or butadiene/acrylonitrile polymers optionally containing carboxyl groups.
The former compositions used industrially are particularly useful for alcohol or alcohol-acetate based inks. The latter commercially new compositions are particularly useful in hydrocarbon-based inks. The flexographic printing plates, like those made from other natural or synthetic conjugated diolefin hydrocarbon polymers, generally require treatment to reduce the tackiness of the relief printing surface after imagewise exposure and development. Both chlorine and bromine treatments are known for reducing layer tack. Bromine treatment has been found to be effective with respect to flexographic printing plates and particularly those containing optionally carboxyl-containing butadiene/acrylonitrile polymers. Generally, bromination solutions require the handling of acid, acid vapor, and/or free elemental bromine in liquid or gaseous state at some point in their manufacture. For operator safety, it is desirable to exclude handling of such aggressive and dangerous reagents. It is an object of the present invention to provide a process for processing flexographic printing plates that excludes the use of a separate acid or free bromine component. Another object is to provide such a method that can be operated over a pH range from near neutral to acidic conditions. Yet another object is that the dry solid component of the processing solution is stable, readily available and, when combined, a stable material that can be stored dry and subsequently mixed with water and then used as a brominating agent. The object of the present invention is to provide a method by which a mixture can be produced. According to the present invention, a layer of a photosensitive elastomeric composition comprising a conjugated diolefin hydrocarbon and a non-gaseous ethylenically unsaturated compound containing at least one terminal ethylene group is exposed to actinic radiation; An improvement is provided in the method of modifying the surface of a relief flexographic printing plate where the relief is produced by liquid developing the unexposed areas thereof, and the improvement is then developed after drying. The surface is subjected to either (1) post-exposure to a source of actinic radiation, and (2) contact with an aqueous treatment solution of alkali monopersulfate and bromide salt for a period of approximately 15 seconds to 40 minutes. It is a matter of implementation. The photosensitive elastic compositions used in the method of the present invention include polymers of conjugated diolefin hydrocarbons, non-gaseous ethylenically unsaturated compounds, organic radiation-sensitive free radical-generating photoinitiators (or systems) and as discussed below. Includes other additives. This composition can be used in layered form. Alternatively, the layer can be adhered to a flexible support or a temporary support can be used.
Other structures may have a cover sheet and a polymer layer on each side of the photosensitive layer. Useful flexible supports include plastic film and metal sheets, open or closed self-ohmic compression moldable rubber layers, or combinations of plastic film foam and rubber layers. When a combination support is used, the plastic film is generally adjacent to the photosensitive layer. Polyamide coated films such as polyesters such as polyethylene terephthalate provide suitable temporary supports. Examples of such supports include polymeric film supports such as polyethylene terephthalate, flame treated polyethylene terephthalate, electron discharge treated polyethylene terephthalate, polyimide (e.g. the films disclosed in U.S. Pat. No. 3,179,634, which is hereby incorporated by reference). etc.) and thin metal supports such as, but not limited to, aluminum, tinned steel (brushed or polished). Polymeric supports typically range from 0.001 inch
It has a thickness in the 0.007 inch (0.025-0.18 mm) range. 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. .
Examples of foam supports include open or closed cell foams such as polyvinyl chloride, polyurethane,
Examples include ethylene polydiene rubber, neoprene, and others. Examples of compression moldable rubbers include styrene/isoprene block copolymers, butadiene/acrylonitrile copolymers, natural rubber, and others. The photosensitive compositions disclosed herein are developable in their unexposed state in an aqueous, semi-aqueous basic or solvent solution due to the particular polymer binder present in the photosensitive composition. be. Photosensitive layer is 0.0005~0.250 inch (approximately 0.013~6.35mm)
or larger thickness range. One essential component of the photosensitive elastomer composition is an elastomer polymeric binder. Suitable binders include natural or synthetic polymers of conjugated diolefin hydrocarbons. Examples of binders are 1,2
- polybutadiene, 1,4-polybutadiene, butadiene/acrylonitrile, butadiene/styrene, block copolymers of the A-B-A type, such as styrene-butadiene-styrene block copolymers, styrene-isoprene-styrene block copolymers, etc. Examples include copolymers of binders. Block copolymers can be of linear, radial or sequential type. Preferred binders are styrene-isoprene-styrene or styrene-butadiene-styrene block copolymers, and butadiene/acrylonitrile copolymers optionally with carboxyl content. The linear block copolymers useful in the present invention have the general formula A-B-A, where A is independently an inelastic material having a number average molecular weight (n) of 2,000 to 100,000 and a glass transition temperature of 25°C or higher. and B is an elastomeric polymer block having an average molecular weight between about 25,000 and 1,000,000 and a glass transition temperature of about 10° C. or less. ing. Inelastic polymer block A with elastic polymer block B between them
taken together to form unit A-B-A represents a particularly suitable copolymer for use in combination with the photopolymerizable component in the compositions of this invention. This unit can constitute the entire general formula of the copolymer. It may be attached to other polymer chains, or it may be a repeat. Of course, the precision of the unit can be improved within the scope of the invention, for example by using this different inelastic terminal block A, or by creating block or graft polymer substitutions in blocks A and B. It is possible to change the properties of Preferably, the elastomer central block B is a polymer of aliphatic conjugated diolefin, while the inelastic body block A is an alkenyl aromatic hydrocarbon, preferably a vinyl substituted aromatic hydrocarbon, and even more preferably a vinyl monocyclic hydrocarbon. It is formed by polymerizing aromatic hydrocarbons. Block copolymers are described in US Pat. No. 3,265,765 and corresponding British Patent No.
No. 1000090 disclosed in each specification. Particularly preferred classes of copolymers include block copolymers having polystyrene end groups connected by a central portion of polyisoprene or polybutadiene, such as polystyrene-polyisoprene-polystyrene or polystyrene-polybutadiene-polystyrene. The polydiene block is 70-90% by weight of the block copolymer.
Other typical block copolymers useful in the present invention are polystyrene-polybutadiene-polystyrene and polystyrene-polyisoprene-polystyrene block copolymers which are hydrogenated according to the teachings of U.S. Pat. Nos. 3,431,323 and 3,333,024. It is what was done. This hydrogenated block copolymer has the additional advantage of improved heat resistance and oxidation resistance. However, it is desirable to have some residual unsaturation in the hydrogenated block copolymer. The reason for this is that only very small concentrations of monomer are then required in the photosensitive composition to reduce the solvent solubility upon exposure to actinic radiation. Still other typical block copolymers useful in this invention are those in which the end blocks are polyalkylstyrenes, such as poly(α-methylstyrene)-polyisoprene-poly(α-methylstyrene), and those having multiple polymer blocks. For example, polyisoprene-polystyrene-polybutadiene-polystyrene-polyisoprene. The number average molecular weight for block copolymers is
Gelserophane manufactured by Arro Laboratories
29 using 600W membrane and toluene as solvent
It can be measured by membrane permeation at °C.
For inelastic polymer blocks and elastomeric polymer blocks, n is preferably determined as follows. A The molecular weight of the first block (polystyrene) is
It can be determined by gel permeation chromatography (GPC) of end-stopped samples removed immediately after polymerization. The chromatograph is calibrated using commercially available polystyrene molecular weight standards. B The n of the second block (polyisoprene or polybutadiene) can be measured by the following method. (1) Measure n of a polystyrene-polyisoprene (or polybutadiene) di-block polymer sample end-capped and immediately removed after its polymerization by appropriately calibrated GPC, and (2) Subtract n of the first block measured in (A) above from this value. C The n of the third block (polystyrene) can be measured using the same general method. (1) Measure n of a sample of a polystyrene-polyisoprene (or polybutadiene)-polystyrene three-block polymer by appropriately calibrated GPC, and (2) From this value, the 2 obtained in (B) above is determined. -Reducing n of the block polymer. These block copolymers are manufactured by Shell Chemical Company and sold under the trade name "Kraton." Useful butadiene/acrylonitrile copolymers range from about 20,000 to about 75,000, preferably from about 25,000 to about 75,000.
High molecular weight butadiene/acrylonitrile copolymer having a number average molecular weight (n) in the range of about 50,000
(a). n for the polymers described herein can be determined by gel permeation chromatography using a butadiene standard. The acrylonitrile content of the polymer varies from about 10 to about 50% by weight, preferably from about 15 to about 40%. Optionally, the copolymer also has a carboxyl content of 0 to 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%. The copolymer is present in an amount of about 55 to 90% and preferably about 60 to about 75% by weight, based on the total weight of the 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 introduced into the high molecular weight copolymer by adding to the polymerization process a carboxyl-containing monomer such as acrylic or methacrylic acid or a monomer convertible to a carboxyl-containing monomer such as maleic anhydride or methyl methacrylate. can be included. Such polymers are available from several sources, e.g. under the trade name Hyker.
It is commercially available from BFGoodrich Chemical. Another essential component of the photosensitive compositions of the invention is a non-gaseous ethylenically unsaturated compound (b) containing at least one terminal ethylene group. The compound should be capable of forming a high molecular weight polymer by free radical initiated chain extension addition polymerization and be compatible with the high molecular weight polymer (a). Said A-B
Ethylenically unsaturated compounds compatible with -A type block copolymers are disclosed in GB 1366769, which is incorporated herein by reference. Many of these monomers are specifically disclosed below. A group of suitable ethylenically unsaturated compounds includes unsaturated esters of alcohols, in particular such esters of α-methylenecarboxylic acids and substituted α-methylenecarboxylic acids, more particularly such esters of alkylene polyols and polyalkylene polyols. esters, and most especially alkylene polyol di- and triacrylates and polyalkylene polyol di- and triacrylates prepared from alkylene polyols of 2 to 15 carbon atoms or polyalkylene ether polyols or glycols of 1 to 10 ether linkages. can be given. The following specific compounds are other examples of this group. Ethylene glycol diacrylate, diethylene glycol diacrylate, glycerol diacrylate, glycerol triacrylate,
Trimethylolpropane triacrylate, ethylene glycol dimethacrylate, 1,3-propanediol dimethacrylate, 1,2,4-butanetriol trimethacrylate, 1,4-cyclohexanediol diacrylate, 1,4-
Benzenediol dimethacrylate, 1,2-benzenedimethanol diacrylate, pentaerythritol triacrylate, pentaerythritol tetramethacrylate, 1,3-propanediol diacrylate, 1,3-pentanediol dimethacrylate, p-α,α-dimethyl Benzyl phenyl acrylate, tertiary butyl acrylate, N,N-diethylaminoethyl acrylate, diethylaminoethyl methacrylate,
1,4-butanediol diacrylate, hexamethylene glycol diacrylate, decamethylene glycol diacrylate, 2,2-dimethylolpropane diacrylate, tripropylene glycol diacrylate, 2,2-di(p-hydroxy-phenyl)propane diacrylate,
2,2-di(p-hydroxyphenyl)propane dimethacrylate, polyoxyethyl-2,2-
Di(p-hydroxyphenyl)propane triacrylate (molecular weight 462), 1,4-butanediol dimethacrylate, hexamethylene glycol dimethacrylate, 2,2,4-trimethyl-1,
3-pentanediol dimethacrylate, 1-phenylethylene-1,2-dimethacrylate, trimethylolpropane trimethacrylate, triethylene glycol diacrylate, ethylene glycol acrylate phthalate, polyoxyethyltrimethylolpropane triacrylate,
Diacrylate and dimethacrylate esters of diepoxy polyethers derived from aromatic polyhydroxy compounds such as bisphenol novolaks and similar compounds such as those described in U.S. Pat. No. 3,661,576, incorporated herein by reference, molecular weight 200-500 polyethylene glycol bisacrylates and methacrylates and more. Other groups of suitable ethylenically unsaturated compounds include, for example, the compounds disclosed in U.S. Pat. No. 2,927,022, which is incorporated herein by reference; and in particular at least one and preferably most of such bonds are conjugated to double bonded carbons, including carbon-carbon double bonds and carbon-heteroatom (e.g. nitrogen, oxygen and sulfur) double bonds. I can give you what I have. Preferred are such materials when ethylenically unsaturated groups, especially vinylidene groups, are conjugated with ester or amide structures. Examples of certain such compounds include unsaturated amides, especially unsaturated amides of α-methylenecarboxylic acid and especially α-ω-diamines and oxygen-interrupted ω-diamines, such as methylenebisacrylamide, methylenebismethacrylamide, ethylene. Bismethacrylamide, 1,6
-hexamethylenebisacrylamide, diethylenetriamine trismethacrylamide, 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, diallyl fumarate, etc. can give. 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 ( 1:1), adducts of itaconic anhydride with liquid butadiene/acrylonitrile polymers containing terminal amino groups, and U.S. Pat. No. 3,661,576 of itaconic anhydride with diacrylate and dimethacrylate esters of diepoxy polyethers. Additives mentioned in the specification,
Mention may be made of polybutadiene and butadiene/acrylonitrile copolymers containing terminal and pendant vinyl groups, and unsaturated aldehydes such as sorbaldehyde (2,4-hexadienal). Ethylenically unsaturated compounds that are water-soluble or contain carboxyl or other alkali-reactive groups are particularly suitable when aqueous base development systems are used. Additionally, the polymerizable ethylenically unsaturated polymers and similar materials described in US Pat. Nos. 3,043,805 and 2,929,710 can be used alone or in admixture with other materials. Acrylic and methacryl esters of ethylene oxide and polyhydroxy compound adducts, such as those described in US Pat. No. 3,380,831, are also useful. Optical crosslinking polymers disclosed in US Pat. Nos. 3,418,295 and 3,448,089 can also be used. All of these patent specifications are incorporated herein by reference. The weight ratio of the block copolymer used to the addition polymerizable ethylenically unsaturated compound used is
99:1 to about 1:1. The amount of unsaturated compound present in the photosensitive composition containing the butadiene/acrylonitrile copolymer should range from about 2 to about 40 percent by weight, based on the total weight of the composition. Specific amounts will vary depending on the particular polymer used to obtain optimal results. Preferably the amount of unsaturated compounds is about 5% to about 25%
within the range of The ethylenically unsaturated compound preferably has a boiling point of about 100° C. or higher at normal pressure. The most preferred ethylenically unsaturated compounds are triethylene glycol diacrylate, triethylene glycol dimethacrylate, hexamethylene glycol dimethacrylate and hexamethylene glycol diacrylate. The photosensitive composition of the present invention does not substantially scatter actinic radiation when in the form of a thin layer as described above. To ensure a substantially transparent mixture, i.e. a non-radiative scattering mixture, the polymeric binder component should be compatible with the ethylenically unsaturated compound in the proportions used, and preferably be compatible with the ethylenically unsaturated compound. Should be soluble. "Compatibility" refers to the ability of two or more components to remain dispersed with each other without causing any significant scattering of actinic radiation. Compatibility is often limited by the relative proportions of the components, and incompatibility is evidenced by the formation of haze in the photosensitive composition. Some slight haze before or between exposures can be tolerated with such compositions in the production of printed reliefs. However, if fine detail is desired, haze should be completely excluded. The amount of ethylenically unsaturated compound or any other ingredient used is therefore limited to a concentration that does 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 system (c). Practically any organic radiation-sensitive free radical-generating 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. Because process transparencies transfer heat generated from conventional sources of actinic radiation, and since photosensitive compositions are typically produced under conditions that produce high temperatures, free radical-generating compounds must be present at temperatures below 85°C and above. Preferably, it is thermally inactive at temperatures 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 relatively short exposures. 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. Free radical generating systems absorb radiation in the range of about 2000 to about 800 Å, which is about 2500 to about 8000 Å.
Å, and preferably has an actinic radiation absorption band with a molecular extinction coefficient of at least about 50 in the range of about 2500 to about 5000 Å. The expression "actinic radiation absorption band" refers to a radiation band active to generate the free radicals necessary to initiate polymerization or cross-linking of unsaturated materials. A free radical generating system may include one or more compounds that directly generate free radicals when activated by radiation. It may also include multiple compounds, one of which generates free radicals after being made to do so by a radiation-activated sensitizer. A large number of such free radical-generating compounds can be used in the practice of this invention, and include 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-diphenylethane), 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 butyl ether and benzoin phenyl ether, Methylbenzoin, ethylbenzoin and other benzoins, 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)-4,5-diphenylimidazolyl 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-methylmercapto phenyl)−
4,5-Diphenylimidazolyl dimer and other US Patent Nos. 3479185 and 3784557, and British Patent Nos. 997396 and 1047569
Disclosed in each specification of the issue. These patent specifications are incorporated herein by reference. The imidazolyl dimer can be used with free radical-generating electron donors such as 2-mercaptobenzoxazole, leuco crystal violet or tris(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 can also be used. Other examples of suitable initiators are disclosed in US Pat. No. 2,760,863, which is incorporated herein by reference. The photosensitive composition may also contain a small amount of a thermal addition polymerization inhibitor, for example from 0.001 to 2.0%, based on the weight of the total solvent-free photosensitive composition. Suitable such polymerization inhibitors include hydroquinone and alkyl and aryl substituted hydroquinones, 2,6-
Di-tert-butyl-4-methylphenol, p-methoxyphenol, tertiary-butylpyrocatechol, pyrogallol, β-naphthol, 2,6-di-tert-butyl-p-cresol, phenothiazine, pyridine, nitrobenzene, di Nitrobenzene and the nitrosodimer inhibitor system described in US Pat. No. 4,168,982, incorporated herein by reference. Other useful inhibitors include p-toluquinone, chloranil and thiazine dyes such as thionine blue G (CI52025), methylene blue B (CI52015) and toluidine blue (CI52040). Such compositions can be photopolymerized or photocrosslinked without removing the inhibitor. Preferred inhibitors are 2,6-di-tert-butyl-4-methylphenol and p-methoxyphenol. The oxygen and ozone resistance of printed reliefs can be improved by including in the photosensitive composition appropriate amounts of compatible, well-known antioxidants and/or antiozonants. Antioxidants useful in this invention include alkylated phenols such as 2,6-ditertiary-butyl-4-methylphenol, alkylated bisphenols such as 2,2-methylenebis-(4-methyl-6-tertiary-butylphenol),
butylphenol), 1,3.5-trimethyl-
2,4,6-tris(3,5-di-tert-butyl-
4-hydroxybenzyl)benzene, 2-(4-
Hydroxy-3,5-ditertiary-butylanilino)
-4,6-bis-(n-octylthio)-1,3,
Mention may be made of 5-triazine, polymerized trimethyldihydroquinone and dilaurylthiopropionate. Azonation inhibitors useful in the present invention include microcrystalline wax and paraffin wax, dibutylthiourea, 1,1,3,3-tetramethyl-2-thiourea, antiozonant AFD (product of Nafton), norbornene. For example, di-5-norbornene-2-methyl adipate, di-5-norbornene-2-methyl terephthalate, Ozone Protector 80 (product of Reichhold Chemicals), 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, polyurethanes, polypentadiene, polybutadiene, furfural-derived resins, ethylene/propylene/diene rubbers, diethylene glycol esters of rosin, and alpha-methylstyrene/vinyltoluene copolymers. The ozone resistance of the printed relief produced can also be improved by annealing it at high temperatures before use. Optionally, the photosensitive composition also includes an immiscible polymeric or non-polymeric organic or Inorganic fillers or reinforcing agents such as polystyrene, organophilic silica, bentonite, silica, powdered glass, colloidal carbon and various types of dyes and pigments can be included. Such materials are used in varying amounts depending on the desired properties of the elastomeric composition. Fillers improve the strength of the elastomer layer, reduce tack, and are also useful as colorants. The photosensitive layer 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. Some common plasticizers include 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 can be prepared by combining the components (a) the polymeric binder, (b) the compatible ethylenically unsaturated compound, and (c) the free radical generating system in any suitable manner. Can be manufactured. For example, the flowable composition may contain, in any order, these components and other desired additives and optionally solvents such as chlorinated hydrocarbons such as methylene chloride, chloroform, methyl chloroform, chlorobenzene, trichloroethylene, tetrachloroethylene and chlorotoluene, ketones such as methyl ethyl ketone. , diethyl ketone and methyl isobutyl ketone, 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, ethyl and butyl acetate. The solvent can later be removed by heating the mixture or extruded 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-radiation scattering composition is formed into a sheet in any desired manner. For example, solvent casting, hot compression molding, calendering or extrusion are suitable methods for producing layers of the desired thickness. The photosensitive elements of the present invention are prepared by forming a photosensitive composition into a layer or self-supporting sheet on a suitable forming wheel, belt or platen by solvent casting or extrusion, calendering or pressing at elevated temperatures. It can be manufactured by folding.
Layers or sheets can be laminated to the surface of the flexible support. Alternatively, it can be adhered by an adhesive blend as described below. If a solution is used, a coating can be produced on the adhesive-containing support. The thickness of this photosensitive layer 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 in flexographic printing and thin hard relief is useful in lithographic printing. Generally, the thickness of the polymerizable layer is about 0.250 inch or less. For example, it varies from about 0.0005 to about 0.250 inches (0.00127 to 0.635 cm) and layers within this thickness range are used for most printing plates. Between the photosensitive layer butadiene/acrylonitrile printing plate and the flexible support is preferably a layer of an adhesive blend comprising at least two polymers selected from the following four polymer groups: Includes merging. (1) a polyester resin of a condensation polymer of ethylene glycol, terephthalic 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) Have a Bruckfield viscosity of 100 to 1200 centipoise and an adhesive activation temperature in the range of 54 to 63 °C when using a #3 Bruckfield spindle at 15% solids by weight and 12 rpm in methyl ethyl ketone. Crystalline thermoplastic polyether polyurethane resin. This polyether polyurethane has a yield point elongation of 15%,
615% elongation at break, 600psi (42.18Kg/cm ² )
It has a 400% elongation modulus and a decrystallization temperature of about 49°C. (3) Polyamide resin, translucent light amber color;
Ball-ring softening point 132-145℃, melt viscosity 40-60 poise at 210℃, ignition point above 299℃,
% water absorption at 1 day is 0.7, at 7 days is 1.6, tensile strength at yield 460 psi (32.34 Kg/cm ² ), tensile strength at break 450 psi (31.64 Kg/cm ² ) and elongation 560%.
(Tensile strength at yield, tensile strength at break and elongation are measured by ASTM method D-1708 at 24°C). (4) Polyamide resin. Translucent bright amber color.
Ball and ring softening point 150~160℃, 218℃
Viscosity of 28-38 poise, daily water absorption% 1.5, 7
2.8 in days.

TABLE (Tensile strength at yield, tensile strength at break and elongation determined by ASTM method D-1708 at the stated temperatures). The number average molecular weight (n) of the resin can be determined by gel permeation chromatography (GPC) using known standards such as butadiene, as is known to those skilled in the art. The weight average molecular weight (w) of a resin can be determined using light scattering techniques using known standards such as polystyrene, polymethacrylic acid, polymethyl methacrylate, etc., as is known to those skilled in the art. Based on the total weight of resin in the adhesive composition (1) 0 to 78
% by weight, (2) 0-78% by weight, (3) 0-94% by weight, and
(4) Certain polymers can be present in the adhesive blend in the range of 0 to 97% by weight. Preferred adhesive blends containing four, three and two resin components are described below, where percentages are based on the weight of total resin components. The percentage ranges for the four-component adhesive blend are as follows: (1) 25-31%, preferably 25%, (2) 25-31%, preferably 25%, (3) 25-19%, preferably 25%, and (4) 25-19%, preferably twenty five%. The percentage ranges for the two three-component adhesive blends A and B are as follows: A(1) 1-78%, preferably 1-65%, (2) 1-78%, preferably 1-65%, and (3) 1-94%, preferably 1-90%. B(1) 1-63%, preferably 1-45%, (3) 1-93%, preferably 1-85%, and (4) 1-97%, preferably 1-90%. % of 5 two-component adhesive blends C-G
The range is as follows. Adhesive blends of C are particularly preferred. C(1) 7-77%, preferably 15-50%, 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) 10-16%, 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.
(53.7 Kg/cm) and typically much greater adhesion force e.g. 8 lb/in (142.86 Kg/cm)
give adhesion values of the photosensitive layer support in the range Kg/m) or higher. 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 antiblocking agents, colorants such as dyes, and the like. Useful anti-blocking agents are preferably polyolefin particles or beads, but also other hard particles or beads such as silicon dioxide, etc. The surfactant dioctyl sodium sulfosuccinate can be used. Preferred polyolefin materials are described in the Examples. The bead size of the antiblocking agent can be larger than the thickness of the adhesive layer. As a result, some of the beads protrude outside the layer of adhesive blend. Many types of colorants or dyes are also useful in the adhesive layer such that such structures are likely to have little or no effect on the degree of adhesion. A preferred dye is Dupont Schilling Blue BL (CI Acid Blue 59). Other useful dyes include methylene violet (CI Basic Violet 5), ``Laxol'' Fast Blue MBSN (CI Solvent Blue 38), ``Pontasil'' Wool Blue BL (CI Acid Blue 59 or CI 50315), ``Pontasil''
Wool Blue GL (CI Acid Blue 102 or C.
I.50320), Victoria Pure Blue BO (CI Basic Blue 7 or CI42595), CI109 Red Die, Rhodamine 3GO (CI Basic Cred 4), Rhodamine 6GDN (CI Basic Cred 1)
or CI45160), fuchsin dye (CI42510),
Calcolet Green S (CI44090), and Anthraquinone Blue 2GA (CI Acid Blue 58)
can be given. The adhesive solution is generally prepared by adding the components, polymer, polyolefin blocking agent, and colorant, to a solvent with continuous stirring in the following order. Useful solvents include mixtures such as methylene chloride/ethyl acetate, methylene chloride/n-butyl acetate, methylene chloride/cyclohexanone, methylene chloride/methanol/cellosolve, etc. and preferably methylene chloride/cellosolve (90/10) mixtures. can give. Additional solvent can be added to compensate for any weight loss. Solvent selection is governed by the need to provide the fastest practical drying rate without forming blisters in the coating and without leaving small amounts of solvent behind. The solvent should also have a solubilizing effect on the dyes that may be present. The adhesive solution is then applied to the flexible support by known means, such as by use of a doctor blade or by coating in a commercially available continuous web coater dryer, to give a coating of about 80%
A dry coating weight in the range of ~500 mg/ ^dm2 , preferably about 260-300 mg/ ^dm2 is produced. The most preferred adhesive layer coating weight is approximately 260
mg/ ^dm2 . Generally adhesive layer is 0.0008~0.001
It has a dry thickness of inches (0.020-0.025mm). For continuous coating, web speeds may range from 15 to 150 ft/min (4.57 to 45.72 m/min), for example.
can be varied to. Drying temperature is 60-130
℃, preferably in the range of 80 to 90℃. A preferred flexible support is flame treated polyethylene terephthalate 0.001 to 0.007 inches (0.025 to 0.18 mm) thick, preferably 0.005 inches (0.13 mm) thick. 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 useful methods and apparatus for flame treatment of polymeric films.
The fuel equivalent ratio φ of the combustible gas mixture is 1.4,
This is 5 (propane flow rate) / [(oxygen flow rate) + (0.21
air velocity)]. All flow rates are standard cubic feet or l/min. Web speed is 175
linear feet per minute (53.34 m/min). The dried adhesive-coated support may be immediately adhered to the photosensitive layer or may be saved for subsequent adhesion. The adhesive-coated support is heated in a press at e.g. 140-160°C.
Approximately 3 at a pressure of 20000~30000psi (1406~2109Kg/ ^cm2 )
It can be laminated to the photosensitive layer for up to minutes and then cooled in a press to below 60°C. Preferably, the photosensitive element is produced by calendering. The photosensitive layer, preferably formed by extrusion through a die, has a 0.005 inch (0.13 mm) thick polyethylene terephthalate film on the side remote from the side adjacent to the adhesive layer; then acts as a protective cover sheet. Other films such as polystyrene, polyethylene,
Polypropylene or other releasable materials can be used. Preferably, between the photosensitive layer and the film cover sheet there is a thin, rigid, flexible, solvent-soluble layer, such as a flexible polymeric film or layer, such as polyamide or ethylene/vinyl acetate copolymer. This flexible polymeric film remains on the photosensitive layer after removal of the film cover sheet. The flexible polymeric film protects the image-containing negative or transparency overlaid thereon for reuse or improves contact or registration with the light-sensitive surface. The element is exposed through the support to polymerize a predetermined thickness of the photosensitive layer adjacent to the adhesive support prior to imagewise exposure using the light source described below. This polymerized portion of the photosensitive layer is referred to as the floor. This floor thickness varies depending on exposure time, exposure source, etc. Exposure is generally 1 to 30 minutes. According to the present invention, the printed relief makes selected portions of the photosensitive layer of said element e.g. process transparent, i.e. substantially transparent to actinic radiation, and portions of substantially uniform optical density opaque to actinic radiation. and by exposure to actinic radiation 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 cross-linking formation, the polymeric binder/ethylenically unsaturated compound composition is converted to an insoluble state in the radiation-exposed portions of the layer, and no significant polymerization or cross-linking occurs in the unexposed portions of the layer. . The unexposed portions of the layer are removed by a liquid developer to the polymeric binder. Process transparencies may be constructed from any suitable material, including cellulose acetate film and oriented polyester film. Actinic radiation from any source and of any type can be used during the photopolymerization process. The radiation may originate from a point source or may be in the form of parallel or diverging beams. By using a broad-field radiation system relatively close to the image-containing transparency, the radiation passing through the transparent portion of the transparency enters as a diverging beam and is therefore continuous in the light-sensitive layer underlying the transparent portion of the transparency. Irradiate the areas that diverge. This results in a polymer relief with the widest width (ie trapezoidal) at the bottom of the photosensitive layer. The upper surface of the relief is then the dimension of the transparent part. Since free radical generating systems that can be activated by actinic radiation generally exhibit their maximum activity in the ultraviolet range, this radiation source should provide an effective amount of this radiation having a wavelength range between about 2500 Å and 5000 Å. be. Suitable such radiation sources include, in addition to sunlight, carbon arcs, mercury vapor arcs,
Fluorescent lamps with ultraviolet radiation emitting phosphors, argon glow lamps, electronic flash units,
and photographic flat lamps. Electron accelerators and electron beam sources through appropriate masks can also be used. Among these, mercury vapor lamps, especially the sunlamp or "blacklight" type, and fluorescent sunlamps are most suitable. Radiation exposure times can vary from fractions of a second to minutes depending on the intensity and spectral energy distribution of the radiation, its distance from the composition and the nature and amount of composition available. Typically, a mercury vapor arc, a solar lamp, or a high ultraviolet emitting fluorescent tube is used at a distance of about 1.5 to about 60 inches (3.8 to 152 cm) from the photosensitive composition. The exposure temperature is not particularly critical. However, it is preferred to operate at about room temperature or slightly above (i.e., from about 20 DEG to about 35 DEG C.). After exposure, the image can be developed by washing with a suitable developer. The developer liquid has good solvent or swelling action on the polymeric binder/ethylenically unsaturated compound composition and does not insolubilize the image or support for the period of time required to remove unpolymerized or non-crosslinked portions. Or it must have little effect on the adhesive layer. Suitable developers include organic solvents such as 2-butanone, benzene, toluene, xylene, trichloroethane, trichloroethylene, methylene chloroform, tetrachloroethylene and solvent mixtures such as tetrachloroethylene/n-butanol and others. When the high molecular weight butadiene polymer component contains carboxyl groups, suitable developers include aqueous bases, which may be supplemented with water-soluble organic solvents. Specific suitable developer mixtures include sodium hydroxide/isopropyl alcohol/water, sodium carbonate/water, sodium carbonate/2-butoxyethanol/water, sodium borate/2-butoxyethanol/water, sodium silicate/2-butoxyethanol. /glycerol/water, sodium carbonate/2-(2-butoxyethoxy)ethanol/water, and 16.6 in water.
Examples include sodium hydroxide (0.5% by weight) in 2-(2-butoxyethoxy)ethanol by volume, but those around this range are preferred. The particular developer combination selected 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 solvent is at a temperature of, for example, 30° to 60°C. Development time is 1 to 120 minutes, preferably 1
It can range from ~25 minutes. In the development step where the relief has been formed, the developer can be applied by any convenient method such as pouring, dipping, spraying or roller application. Brushing helps remove non-polymerized or non-crosslinked portions of the composition. If the printing plate is subjected to aqueous development, then e.g.
A water wash is applied to the developer plate for 300 seconds to remove traces of developer from the plate surface. The expression "aqueous developer" also includes washing with water. After solvent development, the printing plate is kept at room temperature to approx.
Drying for 1 hour at a temperature in the range of 125°C, preferably 60°C. After aqueous development, the printing plate can be dried, but it has been found that the washed aqueous developer plate can be contacted with an aqueous bromine-containing solution while still wet. Hot air drying can be accomplished through the use of a forced hot air dryer or other suitable dryer. The plate is then contacted with an aqueous treatment solution prepared as described below. The plate can be flooded or immersed in the aqueous treatment solution. The latter is preferred. Preferably, the processing solution is held in contact with the printing plate for a period of 15 seconds to 40 minutes, more preferably 1 minute to 10 minutes. The processing solution is preferably used at ambient temperature, but it can be heated up to about 35°C. This treatment solution consists of an alkali monopersulfate such as potassium monopersulfate triple salt (2KHSO ₅ KHSO ₄
K ₂ SO ₄ ) and bromide salts such as potassium bromide in an aqueous solution. Since both components are solid and non-reactive with each other in the absence of moisture, they can be dry mixed and stored in moisture-proof containers for long periods of time before use. The ratio of dry components in the mixture is 98-10 parts alkali monopersulfate and 2-90 parts bromide salt. Potassium salts are particularly preferred. The reason is that their moisture sensitivity is significantly lower. However, other alkali salts such as sodium, lithium, etc. are useful where they are stored separately from each other until dissolution. There is no need to add acid to the processing solution, which is an advantage. This treatment solution is in the higher neutral range and higher than known bromine or chlorine treatment solutions (e.g.
Operable over a PH range including PH values of 8.5 or higher). The overall PH range is 0.7-8.5 or higher. The printing plate can be post-exposed to a source of actinic radiation after development, before or after said bromine treatment. This post-exposure is preferably generally 5 to 15 minutes for the actinic radiation source used for the imagewise exposure. After both treatments, the printing plate is ready for use. The best mode is described in Example 7, where the processing solution is neutral (approximately PH 6.8) and low PH.
(approximately 2.0). At higher PH, the treatment time is preferably 2-10 minutes. At lower PH the preferred treatment time range is 1-2 minutes. Printed reliefs produced from the photosensitive flexographic elements of the invention can be used in all printings, but they are suitable for printings where a clear difference in height between printed and non-printed parts is required. It is applicable and most applicable in particular to flexographic printing where elastic printing parts are required, for example for printing on deformable printing surfaces. These types of printing include, for example, dry offset printing, where the ink is carried by raised parts of the relief, as in conventional letterpress printing, which requires a greater height difference between printed and non-printed areas. , and intaglio printing in which the ink is carried by depressions in the relief, such as 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 small detail and overall dimension even when the element is imagewise exposed on a cylindrical support.
This relief has high impact strength, is tough and abrasion resistant, and has a wide range of ink compatibility, and the relief of plates based on acrylonitrile/butadiene binders can be treated according to the teachings of the present invention. When used, it has improved solvent resistance, especially for alcohol solvents in alcohol-based inks. The following examples are illustrative of the invention, in which parts and percentages are by weight. Ink/Solvent Compatibility Testing The following operations were performed to determine the compatibility and usefulness of printing inks and solvents for flexographic printing plates having layers of the photosensitive elastomeric compositions described herein. used. After measuring the thickness, Shore A hardness (ANSI/ASTM D2240-75) and weight, the exposed and developed printing plate is soaked in a specific solvent or ink for 24 hours. After removal from solvent or ink and pat dry, remeasure its thickness, Shore A hardness and weight. If the thickness change (△T), shore A hardness change (△H) and weight change (△%W) in inches (mm) satisfy the following criteria, the printing plate is
Or it is considered to be compatible or excellent with respect to ink (E). △T: 0.003 inch (0.076 mm) △H: -5 shore A unit △%W: 3.5% The printing plate is certified with respect to its solvents and/or inks if the following criteria are met or exceeded: considered to be incompatible or unsatisfactory (U). △T: 0.012 inches (0.305 mm) △H: -20 shore A units △%W: 7.0% If in the range intermediate between the above two criteria, the treated printing plate will be treated with respect to its solvent and/or ink. of variable or intermediate utility (I). The overall evaluation is provided separately in the Examples below. Tack Test The tack of exposed and developed printing plates of the present invention can be tested as follows. (1) Wipe the surface clean with isopropanol. (2) Use a toilet such as Scotto Brand 510 toilet toilet with a 500g weight.
Plate surface (1 inch x 2 inch,
2.54cm x 5.08cm). (3) Remove stains and record the results. (A) No tack - no tack (B) slight tack - sticks but peels off from the surface (C) tack - peels off but leaves some fibers on the plate (D) very tacky - Sticking and tearing of the tissue when peeled off. A person skilled in the art can identify non-stick or grade (A) printing plate surfaces by touch or touch with a fingertip. Both methods have been used. All treated samples below are untacked. Example 1 An adhesive solution is prepared from the following ingredients. Component amount (parts) Polyamide resin (3) Rod No.OF5237 63.1 Polyester resin (1) 27.0 Polyolefin 9.8 Dupont Milling Blue BL dye (CI acid blue 59) 0.1 The above polyamide resin (3) is a product of Henkel Adhesive Company. "Macromelt" 6238, which is translucent, light amber in color, and has a ball-and-ring softening point of 132-145°C, a melt viscosity of 40-60 poise at 210°C, over 299°C The ignition point of 0.7 per day
%, 1.6% water absorption in 7 days, tensile yield strength of 460psi (32.34Kg/ ^cm2 ), tensile strength at break of 450psi (31.64Kg/ ^cm2 ) and elongation of 560% (tensile yield strength, tensile strength at break and ASTM extension at 24°C
(measured by method D-1708). The above polyester resin is a reaction product of ethylene glycol, terephthalic acid, isophthalic acid and azelaic acid (molar ratio 6:2:1:3) and has n19000 and w37000. The polyolefin mentioned above is Vestofine, a product of Doula Commodities.
SF-616, snow white, molecular weight about 1600,
Density of about 0.96 at 20℃, penetration hardness of 0.5-1.0 at 25℃,
It has a melting point of about 118-128°C, and about 85% of it has a particle size of 10μ or less and 15% of it has a particle size of 10-20μ. Methylene chloride/cellosolve solvent (90/
10) Add the above ingredients in order to the mixture to form a solution of about 16% solids. Polyolefin beads do not dissolve. The mixture is continuously stirred during and after addition of the ingredients to form a solution. Any weight loss during mixing is compensated by the 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 (205°C). The adhesive coated polyethylene terephthalate support is the thickness of the finished printing plate.
Place adhesive side up in a dammed steel platen to 0.080 inch (2.03 mm) thickness. Place the adhesive coated support and platen on a press and extrude a sheet of the photosensitive composition on a 0.005 inch (0.13 mm) thick polyethylene terephthalate support [0.090 inch (approx.
2.29 mm) thick] on top of it, support side up, and cover this with a steel plate. This cover sheet carrying a polyamide layer is produced by coating a polyethylene terephthalate film with the solution described below using an extrusion die coater. Ingredients (%) Methylene chloride 81.0 Methanol 2.0 N-methylpyrrolidone 10.0 Polyamide resin 7.0 The above polyamide resin is Henkel Adhesive Company's product "Macromelt" 6900, which is virtually colorless. Ring and ball softening point of 266-302〓, melting index of 5-15g/10 min at 347〓, ignition point of 570〓,
Water absorption of 0.2% in 1 day and 0.5% in 7 days,
Tensile yield point of 1200 psi and tensile failure point of 3500 psi (these are 24
(measured at °C). Extruded sheets of photopolymerizable compositions are made by blending the following ingredients and extruding the blend through a die at 170°C.

[Table] The above polyethylene sebacate is Paraplex G-30 low molecular weight polyester resin (Rohm &
Haas product). Increase temperature and apply pressure gradually.
This spreads the photopolymerizable sheet over the dammed portion of the platen. After the sheet is evenly distributed, increase the temperature to 160℃, and then 20000~
A pressure in the range of 30000 psi (1406-2109 Kg/cm ² ) is applied and held there for 3 minutes. This assemblage is pressed during pressing by running water through the press platen.
Cool to below 60℃. The formed laminated element is removed from the press and placed, support example side up, in the exposure unit described below. A general exposure of the element in air at atmospheric pressure for 4 minutes through the support is applied to polymerize the photopolymerizable layer adjacent to the adhered support to a predetermined thickness.
This overlapping portion of the element is referred to as the "floor." Next, add this element to Sylvania BL-VHO.
"Cyrel" 3040 with fluorescent lamp
Place it in the exposure unit (DuPont product name). The photopolymerizable surface is covered with an image-containing transparency (negative) and the element is exposed under vacuum for 15 minutes. The duration of exposure is a function of the thickness of the photopolymer sheet, the thickness of the polymeric floor, and the type of image-containing transparency used. After exposure, the transparency is removed and the exposed element is placed in a rotating drum-brush type "Shillel" 3040 processor. Perchlorethylene (75% by volume)/n-butanol (25% by volume)
The unpolymerized portion of the element is removed in the processor by washing with solvent for 15 minutes. A 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℃ for 1 hour. The dried plate is post-exposed for 10 minutes in air using the same exposure source used for the imagewise exposure. This plate has a shore A2 hardness in the range 56-60. The dry printing plate is immersed in either the monopersulfate-bromide treatment solution or the chlorine solution at room temperature as described in Table 1 below. The changes in plate thickness, hardness and weight percent for various solvent mixtures and/or other common printing ink components of exposed, developed and dried printing plates are measured. The values listed in Table 1 are determined using the ink/solvent compatibility test described above. An evaluation is listed for each sample.

【table】

TABLE The results listed in Table 1 show that bromine treatment provides improved printing plates compared to printing plates treated with chlorine solutions. Intermediate and unsatisfactory ratings resulting after bromine treatment are observed for solvents or solvent mixtures that are outside the normal solvent concentration range known to be useful by those skilled in the art. Example 2 As described in Example 1 except that the unexposed image areas were removed in the processor by washing with 16.6% by volume in water and 0.5% by weight sodium hydroxide in 2-(2-butoxyethoxy)ethanol for 15 minutes followed by a 2-minute water wash. The ink/solvent compatibility of bromine- and chlorine-treated light-sensitive flexographic printing plates is compared in this example. Table 2 below lists various solvent mixtures and/or other common printing ink components identified by the numbers given in Example 1, including ΔT, ΔH,
Comparisons are made with respect to Δ%W and ratings are listed for each example.

【table】

【table】

[Table] (h) is a control sample that was not treated with Clorox.
From the results listed in Table 2, it can be seen that chlorine treatment has virtually no effect on the ink solvent. Improved results are achieved by bromine treatment. Samples 5-8 show unsatisfactory results because their solvent mixtures are outside the known useful concentration range. Example 3 This example illustrates the interchangeability of post-exposure and aqueous processing steps. Three types of photosensitive flexographic printing plates are manufactured. The first plate, designated "Plate A", is manufactured as described in Example 2. A second plate, designated "Plate B", is manufactured as described in Example 1. The third plate, designated "Plate C", is for example Schiller
Flexographic Printing Plate A flexographic printing plate containing a 0.112 inch (~2.85 mm) thick styrene-isoprene-styrene block copolymer. Plates A, B and C in Sylvania BL-
It is placed support side up in a Schiller 3040 exposure unit (registered trade name of DuPont) equipped with a VHO fluorescent lamp and exposed in air at atmospheric pressure for 240 seconds. The plate was then imagewise exposed for 10 minutes as described in Example 1 (cover sheet removed for plate C) and then washed for 16 minutes in perchloroethylene (75% by volume)/n-butanol (25% by volume) solvent ( Plates B and C) or 16% by volume 2-(2-butoxy-ethoxy) in water
15 of 0.5 wt% sodium hydroxide in ethanol
Perform a minute wash (plate A). Each developer plate is post-exposed as described in Example 1, either after or before the bipartite aqueous treatment described in Example 1. Each plate is soaked for 24 hours in the indicated solvent (see Example 1 for solvent name) and the Δ%W of the dried plate is determined. The results are shown in Table 3. "Pre" here refers to aqueous processing before post-exposure.

[Table] From the results shown in Table 3, there is no significant difference between the results obtained by the two series of experiments. Example 4 This example illustrates the effect of varying aqueous treatment times with solutions of the invention and chlorine solutions. Photopolymerizable elements are prepared as described in Example 3 (plates A, B and C) with the following variations. Back exposure is 150 seconds. Imagewise exposure is for a total of 10 minutes (no image-containing transparencies) with the cover sheet in place. Aqueous development takes 15 minutes. Forced hot air drying is for 30 minutes. The aqueous treatments of the invention are 0 (control), 2 and 8 minutes (labeled 1). Chlorination times (labeled 2) are 0.5 and 2 minutes. The change in plate thickness, hardness, and weight percent of each element is determined over the stated processing time (minutes) by an ink solvent compatibility test. The results are shown in Table 4. Solvent/mixture numbers are the same as described in Example 1. Plate thickness (△
The values for the change in T) are expressed in mm.

【table】

【table】

【table】

[Table] From the results listed in Table 4, for chlorine treatment (2)
There is no significant change in plate evaluation for increasing treatment times from 0.5 minutes to 2.0 minutes and according to process (1) of the invention from 2 minutes to 8 minutes. Example 5 This example illustrates the stability of a mixture of potassium monopersulfate triple salt and potassium bromide used in the preparation of an aqueous processing solution. 20.0g of 2KHSO ₅・KHSO ₄・K ₂ SO ₄ and 2.0g
of potassium bromide dry powder and 9
Store in a plastic bottle protected from air and moisture for several months. No obvious changes in the appearance of the powder are observed upon storage. at the end of this period
11.0 g of this mixture are dissolved in 100 ml of water and this solution (PH 1.7) is used to treat printing plate A and printing plate C as described in example 2 and example 3, respectively. The printing plate is rated E. The example is repeated by adding the potassium salt to the water without storing it together in the preparation of the treatment solution. These printing plates are rated E. The results of this example show that when the dry powder mixture used to prepare the processing solution of the invention is stored for an extended period of time, the plate rating does not change compared to when the salt components are mixed individually just before their use. Example 6 This example illustrates the improvement obtained using the aqueous treatment solution of the present invention as compared to chlorination. A photosensitive flexographic printing plate is prepared as described in Example 1. Table 5 below lists various solvent mixtures and/or other common ink components identified by the numbers in Example 1.
T, ΔH and Δ%W are compared.
Ratings are listed for each example.

【table】

EXAMPLE 7 This example shows preferred aqueous processing solutions according to the invention in several solvents or solvent mixtures (one of which is
PH is approximately 6.8, and the other is PH approximately 2.0). Photosensitive flexographic printing plates are Example 2 (Plate A), Example 1 (Plate B) and Example 3.
(Plate C). The printing plates are exposed and developed using the method described in Example 3. The post-exposure is carried out before the aqueous processing as described in Example 1, and the aqueous processing is carried out as described in Example 1.
It's a minute. The preferred treatment solution is used to treat plates A, B and C, and the plates are then tested in the solvent or solvent mixture identified by the numbers in Example 1. The measured thickness, hardness and weight percent changes and ratings for each treated plate are listed in Table 6 below. Treatment solution A (PH1.8±0.2) This solution is produced as follows. 100g of 2KHSO ₅ .
Add KHSO ₄・K ₂ SO ₄ . Then add 5 g of KBr and stir thoroughly. Processing Solution A is particularly useful for processing times of 1-2 minutes. Treatment solution B (PH6.6±0.2) This solution is produced as follows. Add 10g of 2KHSO ₅ / KHSO ₄ / K ₂ SO ₄ to the water in Step 1 while stirring thoroughly. Then add 10 g of KBr and stir thoroughly. Processing Solution B is particularly useful with processing times of 2 to 10 minutes.

【table】

TABLE The results set forth in Table 6 show that plate evaluation does not change significantly when changing the PH of the processing solution used for the three types of plates from about 2.0 to about 6.8. Example 8 A photosensitive printing plate is prepared as described in Example 2, except that after aqueous alkaline development and water washing the printing plate is immersed in the processing solution described in Example 1.
The printing plate was then dried and Example 1
Post-expose as described. When using 2-propanol as the solvent, this printing plate
It is evaluated as.

Claims (1)

[Scope of Claims] 1. A layer of a photosensitive elastomeric composition comprising a conjugated diolefin hydrocarbon polymer and a non-gaseous ethylenically unsaturated compound containing at least one terminal ethylene group is exposed to actinic radiation. imagewise exposed to radiation;
To produce a relief by liquid developing its unexposed areas, after drying the developed surface is subjected to either (1) post-exposure to a source of actinic radiation and (2) approximately 15 seconds to 40 minutes. A method for modifying the surface of a relief flexographic printing plate, characterized in that contact with an aqueous treatment solution of an alkali monopersulfate and bromide salt of 2. A method according to claim 1, wherein the printing plate is immersed in an aqueous processing solution. 3. The conjugated diolefin hydrocarbon polymer is a polymer selected from butadiene/acrylonitrile, butadiene/acrylonitrile/acrylic acid, butadiene/styrene, styrene-butadiene-styrene block copolymer, and styrene-isoprene-styrene block copolymer. , a method according to any one of claims 1 or 2. 4. The flexographic printing plate comprises (a) a number average molecular weight of from 20,000 to 75,000, an acrylonitrile content of from 10 to 50% by weight, and an acrylonitrile content of from 0 to 15, based on the total weight of (A) the flexible support and (B) the composition. (b) a high molecular weight butadiene/acrylonitrile copolymer having a carboxyl content of 55 to 90% by weight; (b) containing at least one terminal ethylene group; 2 to 40 non-gaseous ethylenically unsaturated compounds compatible with the polymer of (a)
(c) 0.001-10% by weight of an organic radiation-sensitive free radical-generating system activatable by actinic radiation to initiate polymerization of unsaturated compounds; and (d) 0-15% by weight of a compatible plasticizer. imagewise exposing the photosensitive elastomeric element comprising a layer of a photosensitive elastomeric composition and optionally a layer of an adhesive composition between layers (A) and (B) and applying it to a liquid. 3. A method according to claim 1, wherein the method is produced by developing. 5 (A) Sheet support, (B)(1) Glass transition temperature of 25°C or higher and 2000~
at least two thermoplastic non-elastic polymer blocks having a number average molecular weight of 100,000, and a glass transition temperature between said thermoplastic non-elastic polymer blocks of less than or equal to 10°C;
at least 30% by weight of at least one solvent-soluble thermoplastic elastomeric block copolymer containing an elastomeric polymer block having a number average molecular weight of 25,000 to 1,000,000; (2) at least one terminal ethylene at least 1% by weight of an addition-polymerizable ethylenically unsaturated compound containing functional groups; and (3) a polymerizing amount of a polymerization initiator activatable by actinic radiation. Imagewise exposure of a photosensitive elastomeric element comprising a layer of a sensitive elastomer composition, a flexible cover sheet, and a flexible polymeric film interposed between said cover sheet and the surface of said layer. 3. A method according to claim 1, wherein the relief flexographic printing plate is produced by and liquid development. 6 the processing solution is approximately neutral and contains essentially 5 to 20 parts by weight of an alkali monopersulfate;
Claim 4 consisting of 5 to 20 parts by weight of alkali bromide and 1000 parts by weight of water.
or the method described in any one of Section 5. 7 The processing solution is acidic and essentially
100 parts by weight of alkali monopersulfate, 5
6. A process as claimed in claim 4 or 5, comprising parts by weight of alkali bromide and 1000 parts by weight of water. 8. Claim 1, wherein the treatment solution is prepared by combining alkali monopersulfate salt, bromide salt dry mixture and water.
The method described in section. 9 Monopersulfate salt and bromide salt are
9. The method of claim 8, wherein 2KHSO ₅ .KHSO ₄ .K ₂ SO ₄ and potassium bromide. 10. The method of claim 8, wherein the ratio of dry ingredients in the mixture is from 98 to 10 of the alkali monopersulfate and from 2 to 90 of the salt. 11. The method of claim 9, wherein the treatment solution has a pH of about 0.7 to 8.5.