MXPA00008458A - Process for the continuous liquid processing of photosensitive compositions having reduced levels of residues - Google Patents

Abstract

Minimization of developed photosensitive compositions is realized through use of a photoinitiator of hexaarylbiimidazole compound having at least one hydrophilic group.

Description

PROCESS FOR THE CONTINUOUS PROCESSING IN THE LIQUID PHASE OF THE PHOTOSENSIBLE COMPOSITIONS THAT HAVE REDUCED LEVELS OF RESIDUES Field of the Invention This invention relates to a process for the development and / or cleaning of photosensitive compositions that can be developed in aqueous phase in which less waste, or sludge, is produced. More specifically, it relates to processes in which the photosensitive composition includes a hexainrylbiimidazole photoinitiator.

Background of the Invention The photosensitive compositions are well known and are useful as photocurable substances in the formation of printed circuit material, in the formation of lithographic printing plates, and in waterproofing applications. In such systems, actinic radiation hits a material containing photoactive components to induce physical or chemical change in this material. The latent image produced by it can then be processed to form a Ref. 121834 configured mask or an image. Photosensitive systems can be positive work or negative work. In positive work systems, areas exposed to actinic radiation are removed in the post-exposure processing step; In negative work systems, areas not exposed to actinic radiation are removed. Particularly useful compositions are photopolymerizable and / or photocrosslinkable compositions of negative work, hereinafter referred to as "photopolymerizations". In such systems, exposure to actinic radiation initiates polymerization and / or crosslinking reactions, leading to insolubilization of the material in the appropriate developer solvents. The latent image is developed by the treatment with the developing solvent. The photopolymerizable compositions generally contain a binder, a monomeric or oligomeric material capable of polymerization and / or crosslinking, and a photoinitiator. In recent years there has been an increasing emphasis on compositions that are developable in aqueous phase or that are processable in aqueous phase. Such compositions have significant advantages in terms of lower costs and protection of the environment. Systems that can be developed or developed in aqueous phase often use binders that have acid groups which are removable in the aqueous alkaline solution. In continuous processes for the production of printed circuit materials, lithographic printing plates and waterproofing materials, the developer solution is recycled and used repeatedly in the development step. One problem has been the accumulation of waste, collectively known as "mud", in the recycled developer. This sludge reduces the amount of time the developer can be used without cleaning and therefore reduces efficiency. In addition, the mud may be untreatable and difficult to remove. Frequently, after the photocurable substance has served its purpose, it is removed from the substrate in what is known as a cleaning step. There may also be an accumulation of the sludge in the cleaning solution. It may be desirable to have a process for the processing of the water-phase processable photopolymerizable compositions which leads to a lower accumulation of the sludge.

Brief Description of the Invention This invention relates to a process for producing a configuration or template on a substrate, the process produces less mud. The process comprises the steps of: (a) applying a photoresistible substance that can be developed in aqueous phase to a surface of a first substrate, the photoresistible substance comprises a photoinitiator; (b) guiding by images exposure to actinic radiation to produce exposed and unexposed areas in the photocurable substance; (c) treating the photocurable substance exposed to the manner or by means of images with a sample of the aqueous alkaline solution, leading to the removal of the exposed or unexposed areas of the photohardenable substance; and (d) repeating steps (a) to (c) at least 5 times, wherein each repetition uses a new sample of photocurable substance and a new substrate and essentially the same sample of the aqueous alkaline solution; - *** • - * "- •» - «- wherein the photoinitiator comprises at least one hexaarylbiimidazole compound having at least one hydrophilic group, and wherein treating 3 grams of the non-exposed photocurable substance with 100 grams of the aqueous alkaline solution produces less than 0.05 grams of a precipitate. In a second embodiment, this invention relates to a process for the removal of a configuration or template of the photocurable substance processed from a substrate, the process comprising the steps of: (a) treating the photo-hardenable substance processed with a sample of a cleaning solution, leading to the removal of the photo-hardening mask; and (b) repeating step (a) at least 5 times, wherein each repetition uses a new substrate and the processed photocurable substance and essentially the same sample of the cleaning solution; wherein the photocurable substance comprises at least one hexaaplbiimidazole compound having at least one hydrophilic group, and wherein treating 3 grams of the photocurable substance processed with 100 grams of the cleaning solution produces less than 0.05 grams of precipitate.

'• - * - *' - Description of the Preferred Modalities The process of the invention is a continuous process for the development of the photoresistible substances that can be developed in aqueous phase, in which less sludge is produced. By "that can be revealed in aqueous phase" is meant a material in which the areas either exposed or unexposed can be removed preferably by a developer solution which is water based and contains less than 10% by weight of material organic. By "photoresistible substance" is meant a photosensitive composition which can be used to form a printed circuit material, a lithographic printing plate or a waterproofing product. By "mud" is meant a material which accumulates in the developer solution, which is insoluble in the developer solution and reduces the efficiency of the developer solution to allow the redeposition of the material on the already developed substrate.

The first step in the process of the invention is: (a) applying a photoresistible substance that can be developed in aqueous phase to a surface of a first substrate, the photocurable substance comprises a photoinitiator; wherein the photoinitiator comprises a hexaarylbiimidazole compound having at least one hydrophilic group.

The hexaarylbiimidazoles, abbreviated as "HAB", are generally 2,4,5,5-triphenylimidazolyl dimers, and are well known photoinitiators. The HABIS and the photosensitive systems used by the HABIs have been described, for example, in Chambers, U.S. Pat. No. 3,479,185; Chang et al., U.S. Patent No. 3,549,367; Cescon, U.S. Patent No. 3,684,557; Dessauer, U.S. Patents Nos. 4,252,887 and 4,311,783; Chambers et al., U.S. Patent No. 4,264,708; ada et al., U.S. Pat. No. 4,410,621; Tanaka et al., U.S. Patent No. 4,459,349; and Sheets, U.S. Pat. No. 4,622,286. A HABI which is frequently used in photopolymerizable systems, including photocurable substances, is 2, 2'-bis (o-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2-biimidazole, commonly known as "ortho-chloro HABI" (o-Cl-HABI). The alternative nomenclature for o-Cl-HABI is 2, 2'-bis (2-chlorophenyl) -4,4 ', 5,5'-tetraphenyl-1,2-bi-1H-imidazole. Surprisingly and unexpectedly, it has been found that the amount of sludge in a recycled developer solution can be significantly reduced by using a HAB which has at least one hydrophilic substituent, even though the HABI with the hydrophilic substituent is generally substantially insoluble in the Water.

Any hydrophilic substituent can be used since it does not significantly interfere with the photosensitivity of HAB or has an adverse impact on any other properties of the photocurable substance. By "hydrophilic" is meant a substituent which is easily associated with water. Examples of suitable hydrophilic substituents include alkoxy groups, such as methoxy and ethoxy; hydroxy; dialkyl amino groups such as diethylamino and dipropylamino; carboxylic acid groups and their alkyl esters, amides and salts. It is also possible to use more than one type of hydrophilic substituent. Alkoxy substituents are preferred, with methoxy being particularly preferred. It is preferred that the HAB also have at least one chloro substituent. Without some chlorine substituent, the HABIs are generally less photosensitive and the resultant photocurable substances require longer exposure times. It is more preferred that HABI have the mere two chlorine substituents. Examples of suitable photoinitiators include: 2,2 ', 5-tris- (o-chlorophenyl) -4- (3,4-dimethoxyphenyl) -4', 5'-diphenyl-biimidazole, abbreviated as "TCDM-HABI"; 2,2 ', 4, 4' -tetra- (o-chlorophenyl) -5,5 '-bis- (3, -dimethoxyphenyl) -biimidazole, abbreviated as "TCTM-HABI"; 2, 2 '-bis- (o-chlorophenyl) -4,4', 5,5 '-tetra- (m-methoxyphenyl) -1,2-biimidazole, abbreviated as "CDM-HABI", 2, 2' - bis (2-ethoxyphenyl) -4,4 ', 5,5'-tetraphenyl-1,1' -biimidazole, abbreviated as "OE-HABI". The mixtures of the HABIs can also be used. A preferred photoinitiator is TCDM-HABI. The photoinitiators of HABÍ are generally prepared by the oxidizing union of the triphenylimidazoles. The preparation of the substituted triphenylimidazoles has been described in Cescon, U.S. Pat. No. 3,784,557, and Dessauer, U.S. Pat. No. 4,311,783. Oxidative binding reactions have been described by Hayashi et al., In Bull. Chem. Soc. Japan 33, 565 (1960) and Zimmerman et al., Angew. Chem, 73,808 (1961). The preparation of the TCDM-HABI has been described in Sheets, U.S. Pat. No. 4,622,286. In some cases, reaction mixtures in which more than one HABI is produced can be used without separation and complete purification. As described in Sheets, U.S. Pat. No. 4,622,286, a mixture of HABIs containing TCDM-HABI can be used, in particular, a mixture of 2,4,5-triphenylimidazolyl dimers which are the product of 2- (o-chlorophenyl) -4,5- diphenylimidazole and 2,4-bis- (o-chlorophenyl) -5- [3,4-dimethoxyphenyl] -imidazole by oxidizing bond, a The product of the reaction is 2,2 ', 5-tris- (o-chlorophenyl) -4- (3,4-dimethoxyphenyl) -4', 5'-diphenyl-biimidazole. Frequently, hydrogen donor compounds are used with HABI photoinitiators in photopolymerizable systems. Suitable hydrogen donors include organic thiols, such as 2-mercaptobenzothiazole, 2-mercaptobenzoxazole, and 2-mercaptobenzimidazole; the tertiary amines; N-phenylglycine; 1, 1-dimethyl-3,5-diketocyclohexane; the ethers; the esters; the alcohols; compounds containing allylic or benzyl hydrogen; the acetals, the aldehydes; and the amides. Such materials have been described in MacLachlan, U.S. Pat. No. 3,390,996. HABI photoinitiators generally have a maximum absorption in the 255-275 nm region of the spectrum with an additional absorption in the 300-375 nm region. Sensitizers can be added to extend the spectral response. A sensitizer is activated by actinic radiation causing the initiator to produce free radicals. Various sensitizers have been described, for example, in U.S. Pat. Nos. 3,554,753; 3,563,750; 3,563,751; 3,647,467; 3,652,275; 4,162,162; 4,268,667; 4,351,893; 4,454,218; 4,535,052; and 4,565,769. A preferred group of sensitizers includes bis (p_- dialkylaminobenzylidene) ketones described in Baum et al., U.S. Pat. No. 3,652,275, and the arylidene aryl ketones described in Dueber, U.S. Pat. No. 4,162,162. Other photoinitiators may also be present to adapt the disclosed image of the photocurable substance to that required for the particular final application. These other photoinitiators may include, but are not limited to, Michler's ketone and Michler's ethyl ketone; benzophenone; the p_-dialkylaminobenzaldehydes; the alkyl esters of the p_-dialkylamino aminobenzoate; polynuclear quinones; the cyclohexadienones; benzoin and benzoin dialkyl ethers; the acetophenone derivatives; the thioxanthones, and others known to those skilled in the art. You can also use mixtures. In addition to the photoinitiator, the photoprotective substance generally contains at least one compound which reacts with the species generated by exposure of the photoinitiator to actinic radiation, causing a change in the physical properties of the photocurable substance. A preferred system is a photopolymerizable system, comprising the photoinitiator, an ethylenically unsaturated compound, and a binder. Although it is not limited to photopolymerisable systems of negative work, the process of the invention will be further described in terms of such systems. The ethylenically unsaturated compound is one which is capable of undergoing cross-linking and / or polymerization initiated by free radicals. Such compounds are generally known as monomers or oligomers, although polymers having reactive pendant groups can also be used. Such compounds are well known in the art and have been described, for example, in "Light-Sensitive Systems: Chemistry and Application of Nonsilver Halide Photographic Processes" by J. Kosar (John Wiley S Sons, Inc., 1965); "Imaging Processes and Materials Neblette's Eighth Edition" edited by J. Sturge, V. Walworth and A Shepp (Van Nostrand Reinhold, 1989); and "Photoreactive Polymer - The Science and Technology of Resists" by A. Reiser (John iley &Sons, 1989). Typical monomers are: unsaturated esters of alcohols, preferably the ester of polyols with acrylic or methacrylic acid, such as t-butyl acrylate, cyclohexyl acrylate, hydroxy-Cl-ClO-alkyl acrylate, butanediol diacrylate, hexamethylene glycol diacrylate, trimethylolpropane triacrylate, polyoxyethylated trimethylolpropane triacrylate, diethylene glycol diacrylate, glycerol triacrylate, ethylene glycol dimethacrylate, tri- and tetraacrylate and methacrylate pentaerythritol; acryloxy- and methacryloxy-alkyl bisphenol A ethers, such as the di- (3-acryloxy-2-hydroxypropyl) ether of bisphenol A and di- (3-acryloxy-2-hydroxypropyl) ether of tetrabromo-bisphenol A; unsaturated amides, such as 1,6-hexamethylene bis-acrylamide; vinyl esters, such as divinyl succinate, divinyl phthalate, and divinyl-benzene-1,3-disulfonate; styrene and derivatives thereof; and N-vinyl compounds, such as N-vinyl carbazole. The binder is a material for the formation of a film which can contain the reactive groups. For an aqueous processability, the binders must be able to be revealed by an aqueous alkaline solution. By "revealable" it is meant that the binders are soluble, swellable or dispersible in the developer solution. Preferably, the binder is soluble in the developer solution. Binders such as acidic, polymeric, organic compounds are particularly preferred. One or more binder compounds can be used. One class of binders which is useful in the process of the invention are vinyl addition polymers containing free carboxylic acid groups. These were prepared from 30-94 mole percent of one or more alkyl acrylates and 70-6 mole percent of one or more ethylenically unsaturated carboxylic acids alpha-beta; more preferably from 61-94 mole percent of two alkyl acrylates and 39-6 mole percent of an ethylenically unsaturated alpha-beta carboxylic acid. Suitable alkyl acrylates for use in the preparation of these polymeric binders include methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, and methacrylate analogues. Suitable ethylenically alpha-beta unsaturated carboxylic acids include acrylic acid, methacrylic acid, crotonic acid, maleic acid or maleic anhydride, and the like. Binders of this type, including their preparation, are described in German Application, OS 2,320,849, published on November 8, 1973. Also suitable are styrene copolymers and styrenes substituted with an unsaturated carboxyl-containing monomer, as described with detail in British Patent 1,361,298. Other components conventionally added to the photopolymerizable compositions may be present to modify the physical properties of the film. Such components include: plasticizers, thermal stabilizers, optical brighteners, an ultraviolet radiation absorbing material, color formers, adhesion modifiers, coating aids, and release agents. Also, depending on the application, other inert additives such as dyes, pigments and fillers can be employed. These additives are generally present in minor amounts so that they do not interfere with the exposure of the photocurable substance. Typical compositions for the photopolymerizable photocurable substance are, by weight: photoinitiator (s), 0.1 to 10%, preferably 1 to 5%; ethylenically unsaturated compound (s), 5 to 60%, preferably 15 to 50%; binder (s), 25 to 90%, preferably 45 to 75%; all other components, 0 to 5%, preferably 0 to 4%. A wide variety of substrates can be used in the process of the invention. By "substrate" is meant any natural or synthetic support, preferably one which is capable of existing in a flexible or rigid form. For example, the substrate may be a sheet or metal sheet, a sheet or film of a synthetic organic resin, cellulose paper, fibreboard, and the like, or a composite of two or more of these materials. The particular substrate will usually be determined by the proposed application. For example, when printed circuits are produced, the substrate may be an epoxy board and coated fiberglass with copper, a copper-coated film, or an embossed pattern or configuration of the printed circuit on the board or film. For lithographic printing plates, the substrate may be anodized aluminum. For waterproofing applications, the substrate may be a polyester film or a paper coated with polyester. The photocurable composition can be applied to the substrate by coating from a suitable solvent, such as dichloromethane, methanol, or acetone. Any conventional coating technique can be used. Alternatively, the photocurable composition can be coated or extruded on a polymeric film backing, such as a polyethylene terephthalate film backing, and dried to form a film. This can then be laminated to the substrate, again using conventional techniques. The support film acts as a cover sheet which is removed after exposure. The photocurable film can be protected until it is ready for use by a release film, such as polyethylene or polypropylene, which is removed prior to lamination to the support. The final dry thickness of the photocurable substance on the substrate will depend on the proposed application. The thickness is generally in the range of 5 to 100 microns (0.2 to 4 mils), preferably 13 to 50 microns (0.5 to 2 mils). The second step in the process of the invention is: (b) Directly exposing the images to actinic radiation to produce exposed and unexposed areas in the photocurable substance. Any suitable source or sources of actinic radiation that provide wavelengths within the spectrum that overlap the absorption bands of the photoinitiator and / or the sensitizer can be used to activate photoreactions. By "actinic radiation" is meant the radiation which is active to cause the photoinitiator to initiate the reactions which change the physical properties of the photocurable substance. For photopolymerizable systems, actinic radiation causes the free radicals productions necessary to initiate the polymerization of free radicals of the ethylenically unsaturated compound (s). The radiation can be natural or artificial, monochromatic or polychromatic, coherent or incoherent, and for a high efficiency must correspond closely with the wavelength for the absorption of the initiator system.

Conventional light sources include fluorescent, mercury, metallic additive and arc lamps. The coherent light sources are xenon ion, argon and ionized neon laser beam, as well as a tunable dye laser beam and a neodymium: YAG double frequency laser beam, whose emissions fall into or overlap the absorption bands visible from the sensitizer. The third step in the process of the invention is: (c) treating the exposed substance in a guided manner by the images with a sample of aqueous alkaline solution to remove the areas either exposed or unexposed from the photoresist. In light-curing systems. The unexposed areas are removed. The developer solution is generally a solution from 0.01 to 2% by weight of a water soluble base, in water. Suitable bases include the alkali metal hydroxides, such as lithium, sodium and potassium hydroxide; alkaline metal salts of basic reaction of weak acids, such as lithium, sodium and potassium carbonates and bicarbonates; ammonium hydroxide and tetra-substituted ammonium hydroxide, such as tetramethyl and tetraphenyl ammonium hydroxide; sulfonium salts including hydroxides, carbonates, bicarbonates, and sulfides; phosphates and alkali metal pyrophosphates, such as sodium and potassium triphosphates and pyrophosphates; hydroxides of tetra-substituted phosphonium, arsonium and stibonium, such as tetramethylphosphonium hydroxide. The developer compositions may also contain surfactants. However, the total organic content should be less than 10% by weight, preferably less than 5% by weight. A preferred developer is a 1% by weight solution of sodium carbonate. The developing step can be carried out as a batch or a continuous process using any conventional technique, such as submerging or spraying. The aqueous developer solution may be at room temperature or heated to about 80 ° C. Many commercial processors are available for development. The next steps in the process of the invention are to repeat the first three steps with a new substrate and show photocurable, but using essentially the same developing sample. In other words, the developer is recycled and used again to reveal more photosensitive substance. When more and more photocurable substance is revealed by the revealing solution sample, even in the absence of sludge formation, the developer becomes less effective because it becomes more saturated with the dissolved photohardened substance. Finally, even in the absence of mud formation, the developer solution must be filled in, in which a large volume of fresh solution is added to the solution used, or completely replaced with the fresh developer. In some development processes, a small portion of the developer solution is removed and an equal amount of fresh developer added after each sample of the photo-hardenable substance is processed. These systems are known in the industry as "feeding and purging" systems. In general, a physical property, such as pH, conductivity or UV absorbance, is checked continuously. When this property falls outside a predetermined limit, a small amount of the developer is removed and fresh developer is added to adjust the property to the desired set or hardening point. Since only a small amount of the developer is removed and replaced in each cycle, the sample of the developing solution is essentially the same each time. By "essentially the same" it is understood that less than 20% by volume of the original sample of the developer has been replaced with the fresh developer in any development cycle. uima ^ k iu.

Typically, the developer solution is recycled until approximately 0.74 to 0.92 square meters (8-10 square feet) of photocurable substance having a thickness of 25 microns (1 mil) is revealed by 3.8 liters (one gallon) of developer solution . A maximum of 4.6 square meters (50 square feet) may be revealed in some cases, but this is rarely achieved. In general, this leads to a charge of approximately 30-50 g of photo-hardening substance developed by 1 liter of developer before the developer is filled or replaced. The formation of excess sludge in the developer solution can drastically decrease the amount of the photocurable substance that can be revealed prior to filling or replacing the developer. In the process of the invention, the amount of sludge formation is reduced to a level such that in a standard test, the treatment of 3 g of the non-exposed photoprotective substance with 100 g of the developer solution produces less than 0.05. g of the precipitate. Preferably less than 0.01 g of the precipitate are produced. Although the photosensitive compositions of the invention lead to a lower sludge formation in the development, it is important that the other properties of the photocurable substance are not adversely affected.

In particular, the speed of the photographic process should not be significantly reduced. In some cases, when the photocurable substance is used in the formation of a printed circuit material, the processed portion of the photocurable substance remains a permanent part of the circuit structure. By "processed" is meant the portion of the photocurable substance that remains on the substrate after the exposure and development steps. In positive work systems, the processed photocurable substance represents the unexposed areas of the photoresistible substances. In negative work systems, the processed light-hardened substance represents the exposed areas of the photocurable substance. However, in other cases, after the processed photoresist has served its purpose in, for example, the plating and / or acid etching steps, the processed photo-hardenable substance is removed in a cleaning step. A second embodiment of the present invention is a process for the removal of the processed light-hardening substance that leads to the formation of a small amount of sludge. In the second embodiment, the processed light-hardened substance is removed from a substrate by: (a) the treatment of the photo-hardenable substance processed with a sample of a cleaning solution, leading to the removal of the processed photo-hardening substance; and (b) repeating step (a) at least 5 times, wherein each repetition uses a new substrate and processed photocurable substance and essentially the same sample of the cleaning solution; wherein the photohardenable substance comprises at least one hexaarylbiimidazole compound having at least one hydrophilic group, and wherein treating 3 grams of the photocurable substance processed with 100 grams of the cleaning solution produces less than 0.05 grams of precipitate. The composition of the photohardenable substance, the hexainylbiimidazole photoinitiator, and the substrate, is the same as described above. The photocurable substance is exposed to actinic radiation and is revealed as described above. The cleaning compositions generally must be strong enough to remove the processed photoresist without damaging the substrate or any components on the substrate. The Cleaning compositions are well known in the art and can be found, for example, in "Printed Circuits Handbook" edited by CF Coombs, Second Edition (McGraw-Hill, Inc., 1979) and "Photoresist - Materials and Processes" by WS DeForest (McGraw-Hill, Inc., 1975). For positive work systems, in which non-exposed areas of the photocurable substance are removed in the cleaning step, the cleaner is generally the same as or similar to the solvent solution which was used to coat the photoresist a film or the substrate. Examples of suitable solvents include methylene chloride, acetone, alcohols, and glycol ethers. The solvent mixtures can also be used. For negative work systems, in which the exposed photocurable substance is removed in the cleaning step, the cleaners are generally more severe. The cleaners for the photoresistible substances that can be developed in aqueous phase are generally caustic solutions, such as sodium or potassium hydroxide solutions; aqueous solutions of choline or its derivatives; aqueous solutions of organic amines. Cleaners may include other components to increase cleaning power, such as chlorinated phenols or cresols; or chelating agents. Other additives, such as surfactants or antifoam agents may also be present. The preferred cleaning solutions are aqueous alkaline solutions. Particularly preferred solutions are the sodium hydroxide solutions and the potassium hydroxide solutions. The cleaning step can be carried out as a batch or in a continuous process using any conventional technique, such as submerging or spraying. The cleaning solution may be at room temperature, but in general it is heated to about 50-65 ° C (120-150 ° F), preferably 50-55 ° C (120-130 ° F). Many commercial processors are available for cleaning. The next steps in the process of the invention are to repeat the cleaning step with a new substrate and a processed photocurable sample, but essentially using the same cleaning sample. In other words, the cleaning solution is recycled and used again to remove more processed photoresist. When more and more photohardenable substance is removed by the sample of the cleaning solution, even in the absence of mud formation, the cleaning solution becomes less effective because the it becomes more saturated with the dissolved photohardened substance. Finally, even in the absence of mud formation, the cleaning solution must be filled, in which a large volume of the fresh solution is added to the used solution, or completely replaced with the fresh cleaning solution. As with the development, some cleaning processes use a feed and purge system. By "essentially the same" it is understood that less than 20% by volume of the original sample of the cleaner has been replaced with the fresh cleaning solution in each cleaning cycle. The amount of the photocurable substance that can be removed by a cleaning solution varies considerably with the type of photohardenable substance and the type of the cleaning solution and the equipment used. The formation of the excess sludge in the separating solution can drastically reduce the amount of the photocurable substance that can be cleaned prior to filling or replacement of the cleaning solution. In the process of the invention, the amount of the sludge formation is reduced to a level such that in a standard test, the treatment of 3 g of the photo-hardenable substance processed with 100 g of the cleaning solution produces less than 0.05 g of the precipitate . Preferably less than 0.01 g of the precipitate are produced.

EXAMPLES The invention is illustrated by the following examples which are not proposed to be limiting. All percentages are by weight, unless indicated otherwise.

Glossary Abbreviation Chemical Name CAS # BP Benzophenone 119-61-9 CBT Mixture 50:50, 4, - and 5- 60932-58-3 carboxybenzotriazole 5-C1-BT 5-Chlorobenzotriazole 94-97-3 CD-541 Bisphenol Dimetacrylate 41637-38-1 A Ethoxylated (6 moles of ethylene) CM-HABI 2, 2 '-bis (2-carbomethoxy-phenyl) -4,4', 5,5'-tetraphenyl-biimidazole DBC 2,3-Dibromo-3-611-91-6 phenylpropiophenone DEHA N, N-Diethylhydroxylamine 3710-84-7 E-2627 Poly (methyl methacrylate / 25133-97-5 ethyl acetate / methacrylic acid) (50 / 30/20) EDAB Ethyl-p-dimethylaminobenzoate 10287-53-3 EMK Ethyl Ethyl Ketone 90-93-7 ITX Isopropylthioxanthone 5495-84-1 LCV Crystal Violet Leuco 603-48-5 MEK Methyl Ethyl Ketone nPG n-Phenyl glycine 103-01-5 NK Ester 9PG Propylene Dimetacrylate 25852-49- 7 glycol 400 (7 moles of propylene oxide) O-Cl-HABI 2,2 '-bis (2-chlorophenyl) -124354-60-5 4,4', 5,5'-tetraphenyl-2-bi -lH-imidazole ODAB 2-Ethylhexyl-4- (dimethylamino) 21245-02-3 benzoate OE-HABI 2,2 '-bis (2-ethoxyphenyl) -4,4', 5,5'-tetraphenyl-biim dazol P -31R Block copolymer 31/1 9003-11-6 of propylene oxide and ethylene oxide S-661 Poly (28571-95-1 monoisobutyl / styrene maleate) (42/58) SR604 Monometacrylate of 39420-45-6 propylene glycol (5 moles of propylene oxide) SR9036 Bisphenol dimethacrylate 41637-38-1 A Ethoxylate (30 moles of ethylene oxide) TCDM-HABI 2,2 ', 4-tris (2-chlorophenyl) -100486-97-3 5- (3,4-dimethoxyphenyl) -4', 5'-diphenyl- bi-lH-imidazole TCTM-HABI 2,2 ', 5,5' -tetrakis (2-chloro-71002-23-8 phenyl) -4,4'-bis (3,4-dimethoxyphenyl) -bis- lH- imidazole TMCH 4-Methyl-4-trichloromethyl-2,4-cyclohexandienone VGD Victoria Green Dye 569-64-2 XPD-2470 n-Butyl Acrylate Copolymer / Ethyl Acrylate / Methacrylic Acid (20/13/42/25) All films were prepared by dissolving the components in the indicated solvent and coating on a polyester film of 19 microns (0.75 mils) using a 254 micron (10 mil) inch doctor blade. The coatings were dried with air at 25 ° C to give a layer of dry photocurable film with a thickness of 30.5 microns (1.2 mils).

Mud Test To determine the formation of the mud, a mud test was developed. A developer solution was prepared by dissolving 20 g of sodium carbonate in 2 liters of water and adding 1.5 ml of PluronicV 31R1 (BASF, Mt. Olivo, NJ), which is a plasticizer of the polyoxyethylene / polyoxypropylene copolymer. A 30.5 X 30.5 cm (12 inches by 12 inches) sample of the non-exposed photocurable film that was 30.5 microns (1.2 mils) thick, representing 3.4 g of the photocurable substance, was placed in 100 g of the revealing solution. The sample was allowed to settle until the photocurable sample had dissolved, and the amount of the precipitate was determined according to the following scale: 0 = no yellowish precipitate 1 = light quantity of finely divided yellow material 5 = moderate amount of material yellowish, usually more finely divided 10 = solid, heavy layer of yellowish material on the bottom; the material is usually in the form of flakes The measurements have shown that the evaluations represent the following amounts of the precipitate: 0: μ 0.005 g 1: 0.005 to 0.01 g 5: 0.05 to 0.08 g 10:? 0.1 g Speed of the Photographic Process A copper laminate / photopolymer film was prepared to determine the development time and to test the speed of the photographic process. The photocurable films of 30.5 microns (1.2 thousandths of an inch) were laminated to a rubbed copper FR-4 laminate with 28 g (1 oz) brush, using a hot cylindrical laminator at 1.5 m / min and a cylinder temperature of 105 ° C. The development time was measured as the time required to completely remove the photopolymer from the copper laminate using a 1.5% aqueous solution of sodium carbonate at 85 ° C in a Chemcut CS2000 developer with a spray pressure of 1.97 kg / cm2 ( 28 psi).

The speed of the photographic process was measured using a Stouffer density table of 41 steps. The film was exposed with 10 to 80 mJ / cm2, using a DuPont PC-530 exposure unit (E. I. du Pont de Nemours and Company, Wilmington, DE), and using a total time in the developing chamber of 1.5 times the minimum development time. The last step in which at least 50% of the photopolymer remained was determined. This step, identified as the "fixed step", was reported as the speed of the photographic process. For a commercial product, a photographic process velocity of at least 15 steps maintained at an exposure of 10 mj / cm2 and at least 28 steps maintained at an exposure of 40 mJ / cm2 is desirable. For every 5 steps taken down, the speed of the photographic process was reduced by 50%.

Example 1 This example illustrates the use of different different photoinitiator systems. Examples 1-1, 1-2 and 1-3 represent the invention using the TCDM-HABI with and without benzophenone. Comparative examples C-1A to C-1C illustrate the compositions using o-Cl-HABI, with and without benzophenone. Comparative examples C-1D to C-1F illustrate the compositions that do not have HABI photoinitiators. The photosensitive solutions were prepared having the following compositions: SAMPLE, parts by weight - Component i_2 3 C-1 A C-1B C-1C XPD-2470 65.7 65.7 65.7 65.7 65.7 65.7 TMPEOTA 12 12 12 12 12 12 SR9036 9 9 9 9 9 9 N Ester 9PG 64 6.4 6.4 6.4 64 6.4 SR604 3 3 3 3 3 3 o-Cl-HABI 3 1 0.9 TCDM-HAB1 0.5 1 0 5 - EMK 0.06 0.06 0.15 0.06 0.06 - ITX 0.4 0.4 - 0.4 0.4 pPG 0.5 0.5 - 0.5 0.8 - TMCH 0.25 ODAB EDAB BP 2 - - 5 LCV 0.3 0.3 0.35 0.3 0.3 0.25 VGD 0.04 0.04 0.04 0.04 0.04 0.04 DBC - - 0.25 - CBT 0.02 0.02 0.02 0.02 0.02 0.02 -C1-BT 0.01 0.01 0.01 0.01 0.01 0.01 DEHA 0.02 0.02 0.02 0.02 0.02 0.02 TOTAL 97.5 98 99.49 100 98.03 102.59 SAMPLE, parts by weight Component C-1D C-1E C-1F XPD-2470 65.7 65.7 65.7 TMPEOTA 12 12 12 SR9036 9 9 9 NK Ester 9PG 6.4 6.4 6.4 SR604 3 3 3 o-Cl-HABI - TCDM-HABI - EMK 0.14 0.14 0.16 ITX - 0.5 nPG - 0.5 TMCH - ODAB 2 EDAB - 1.7 BP 5 3 4 LCV 0.35 0.35 0.35 VGD 0.04 0.04 0.04 DBC 0.15 0.15 CBT 0.02 0.02 0.02 5-C1-BT 0.01 0.01 0.01 DEHA 0.02 0.02 0.02 TOTAL 104.8 100.13 102.4 Solutions of 50% solids in acetone were coated to form films. The films were tested to verify the formation of the mud and the speed of the photographic process. The results are given in the following table: SAMPLE - hl hl hl C-1 A C-1B (V mud 0 2 0 10 3 2 Photographic speed 10 mJ / cm2 11 16 12 15 10 9 20 mJ / cm2 16 21 18 21 16 16 40 J / cm2 23 28 25 28 23 23 80 mJ / cm2 29 34 32 34 29 29 -MUESTRA - C-1D D C-1E C-1F Mud 0 0 0 Photographic speed 10 mJ / cm2 10 4 9 20 mJ / cm2 16 10 15 40 mJ / cm2 24 18 23 80 mJ / cm2 30 24 29 It is clear from the above data that at levels where the photographic speed is' acceptable, there is much more mud formation in the compositions with the o-Cl-HABI. The compositions with the photoinitiators of ODAB, EDAB and BP, although they do not have significant mud, have a very slow photographic speed.

Example 2 This example illustrates the use of different photoinitiator systems with different binders. The Examples 2-1, 2-2 and 2-3 represent the invention using TCDM-HABI. Comparative examples C-2A to C-2C illustrate the compositions using o-Cl-HABI. The photosensitive solutions were prepared having the following compositions: SAMPLE, parts by weight - Component 2d ¡i li C-2A C-2B C-2C XPD-2470 65.7 - - 65.7 - S-661 - 65.7 - - 65.7 - E-2627 - - 65.7 - - 65.7 TMPEOTA 12 12 12 12 12 12 SR9036 9 9 9 9 9 9 N Ester9PG 6.4 6.4 6.4 6.4 6.4 6.4 SR604 3 3 3 3 3 3 o-Cl-HABI. . . 3 3 3 TCDM-HABI 1.5 1.5 1.5 EMK 0.06 0.06 0.15 0.06 0.06 0.06 ITX 0.4 0.4 0.4 0.4 0.4 0.4 nPG 0.5 0.5 0.5 0.5 0.5 0.5 LCV 0.3 0.3 0.3 0.3 0.3 0.3 VGD 0.0 0.04 0.04 0.04 0.04 0.04 TOTAL 99.95 98.45 99.95 98.45 99.95 98.45 Solutions of 50% solids in acetone were coated to form films. The movies were tested to verify mud formation, with the results given in the following table.

SAMPLE 2-1 2-2 2-3 C-2A C-2B C-2C Mud 0 4 2 10 3 10 Again, there is significantly less mud formation with the compositions containing TCDM-HABÍ. Note that the levels of o-Cl-HABI and TCDM-HABI were chosen in such a way that coatings of commercially available photographic speeds were obtained. The TCDM-HABI coatings, in effect, had photographic speeds of approximately 25% faster than those with o-Cl-HABI.

Example 3 This example illustrates the use of different photoinitiator systems with a different monomer. Example 3-1 represents the invention using the TCDM-HABI. Comparative Example C-3A illustrates a composition using o-Cl-HABI. The photosensitive solutions were prepared having the following compositions: SAMPLE, parts by weight Component C-3A XPD-2470 65.7 65.7 TMPEOTA 18 18 NK Ester 9PG 6 6 CD541 6 6 o-Cl-HABI - TCDM-HABI 0.25 EMK 0.12 0.06 ITX 0 0.4 p? G 0 0.5 TMCH 0.3 EDAB 2 BP 4 LCV 0.4 0.3 VGD 0.04 0.04 DBC 0.15 CBT 0.02 0.02 5-C1-BT 0.01 0.01 DEHA 0.02 0.02 P-31R1 2.44 TOTAL 106.02 99.17 Solutions of 50% solids in acetone were coated to form films. The films were tested to verify mud formation and photographic speed. The results are given in the following table.

- SAMPLE - hi C-3A Mud 0 3 Photographic speed 10mJ / cm2 14 18 20mJ / cm2 20 24 40 mJ / cm2 26 30 Although this photosensitive composition generally leads to less mud, clearly the composition of TCDM-HABI leads to less mud than the composition of o-Cl-HABI. The photographic speed of the composition of TCDM-HABI could be improved by increasing the concentration of HABI slightly, since it is at a very low level.

Example 4 This example illustrates the effect of different levels of HABI photoinitiators on sludge formation. Examples 4-1 to 4-3 illustrate the compositions of the invention using TCDM-HABI. Comparative examples C-4A to C-4E illustrate the compositions using o-Cl-HABI. The photosensitive solutions were prepared having the following compositions: - SAMPLE, parts by weight - Component H i2 ád C-4A C-4B C-4C XPD-2470 65.7 65.7 65.7 65.7 65.7 65.7 TMPEOTA 12 12 12 12 12 12 SR9036 9 9 9 9 9 9 9 9 NK Ester 9PG 6.4 6.4 6.4 6 6..44 6 6..44 6.4 SR604 3 3 3 o-Cl-HABI 3 1 0.5 TCDM-HABI 0.5 EMK 0.06 0.06 0.06 0.06 0.06 0.06 ITX 0.4 0.4 0.4 0.4 0.4 0.4 nPG 0.5 0.5 0.5 0.5 0.5 0.5 LCV 0.3 0.3 0.3 0.3 0.3 0.3 VGD 0.04 0.04 0.04 0.04 0.04 0.04 TOTAL 99.95 97.95 97.45 99.95 97.95 97.45 SAMPLE, parts by weight Component C-4E C-4E XPD-2470 65.7 65.7 TMPEOTA 18 30.4 SR9036 3 NK Ester 9PG 6.4 SR604 3 o-CI-HABI 3 TCDM-HAB1 - EMK 0.06 0.06 ITX 0.4 0.4 nPG 0.5 0.5 LCV 0.3 0.3 VGD 0.04 0.04 TOTAL 99.95 99.95 Solutions of 50% solids in acetone were coated to form films. The films were tested to verify the formation of the mud, with the results given in the following table. In addition to the evaluation of the visual mud, the samples were centrifuged and the solids collected. The weight of the dry mud, in grams, was determined.

SAMPLE ± J. £ 4 ¿C-4A C-4B C-4C Mud - Calif. 3 0 0 10 6 1 - Weight (g) 0.029 0.004 0.005 0.141 0.068 0.047 - SAMPLE C-4D C-4E Iodo. Calif. 5 9 - Weight (g) 0.054 0.082 It is clear from the above data that higher amounts of TCDM-HABI with lower mud formation can be used. The photographic speeds of the above coatings are such that the samples 4-2 are comparable in photographic speed to the comparative sample C-4A. At the level of the o-Cl-HABI in the comparative sample C-4B, a coating is obtained with a photographic speed not commercially available. Even at this level, the amount of mud is still significantly higher than that obtained with samples 4-2.

Example 5 This example illustrates the use of other HABI photoinitiators of the invention. Examples 5-1 and 5-2 represent the invention using the TCDM-HABI. Examples 5-3 and 5-4 represent the invention using TCTM-HABI. Examples 5-5 and 5-6 represent the invention using carbomethoxy HABI (CM-HABI). Comparative examples C-5A and C-5B illustrate the compositions using o-Cl-HABI. The photosensitive solutions were prepared having the following compositions: v, μd. jan Component á-i Ll 5-4 LL Lé XPD-2470 65.7 65.7 65.7 65.7 65.7 65.7 TMPEOTA 12 12 12 12 12 12 SR9036 9 9 9 9 9 9 NK Ester 9PG 6.4 6.4 6.4 6.4 6.4 6.4 SR604 3 3 3 3 3 3 EMK 0.06 0.06 0.06 0.06 0.06 0.06 TCDM-HABI 1 0.75 - - - - TCTM-HABI - - 1 0.75 - - CM-HABI - - - - 1 0.75 ITX 0.4 0.4 0.4 0.4 0.4 0.4 nPG 0.5 0.5 0.5 0.5 0.5 0.5 LCV 0.3 0.3 0.35 0.3 0.3 0.3 VGD 0.04 0.04 0.04 0.04 0.04 0.04 CBT 0.02 0.02 0.02 0.02 0.02 0.02 -C1-BT 0.01 0.01 0.01 0.01 0.01 0.01 DEHA 0.02 0.02 0.02 0.02 0.02 0.02 TOTAL 99 98.88 99 98.88 100 99 SAMPLE, parts by weight Component C-5A C-5B XPD-2470 65.7 65.7 TMPEOTA 12 12 SR9036 9 9 NK Ester 9PG 6.4 6.4 SR604 3 3 EMK 0.06 0.06 o-Cl-HABI 3 1 ITX 0.4 0.4 nPG 0.5 0.5 LCV 0.3 0.3 VGD 0.04 0.04 CBT 0.02 0.02 5-CI-BT 0.01 0.01 DEHA 0.02 0.02 TOTAL 100 99 Solutions of 50% solids in acetone were coated to form films. The films were tested to verify mud formation and photographic speed. The results are given in the following table.

SAMPLE - Ll 5-2 5-3 5-4 Li Li Iod 1 1 NA 1 1 1 Photographic speed 20 mJ / cm2 19 17 18 16 14 8 40 mJ / cm2 25 23 24 23 20 14 80 mJ / cm2 31 29 30 29 26 20 - SAMPLE - C.5A C-5B Mud 7 3 Photographic velocity 20 mJ / cm2 20 11 40 mJ / cm2 26 17 80 mJ / cm2 30 24 It is clear from the above data that at the levels where the photographic speed is acceptable, there is much more mud formation in the compositions with the o-Cl-HABI.

Example 6 This example illustrates the use of other HABI photoinitiators of the invention. Examples 6-1 to 6-4 illustrate the invention using the TCDM-HABI. Examples 6-5 to 6-8 illustrate the invention using o-ethoxy-HABI (OE-HABI). Comparative examples C-6A to C-6D illustrate the compositions using o-Cl-HABI. The photosensitive solutions were prepared having the following compositions: SAMPLE, parts by weight Component ti 6-2 6_i 6-4 2 0-0 XPD-2470 66.95 66.95 66.95 66.95 65.7 65.7 TMPEOTA 13 19 19 31.4 12 18 SR9036 9 6 - - 9 6 NK Ester 9PG 6.4 6.4 6 - 6.4 6.4 SR604 3 - 4 - 3 - CD-541 - - 6 - - - EMK 0.06 0.06 0.06 0.06 0.06 0.06 TCDM-HABI 0.75 0.75 0.75 0.75 - - OE-HABI - - - - 33 33 ITX 0 0..44 0 0..44 0 0..44 0 0..44 0 0..44 0 0..44 nPG 0 0..55 0 0..55 0 0..55 0 0. .55 0 0..55 0 0..55 LCV 0 0..33 0 0..33 0 0..3355 0 0..33 0 0..33 0 0..33 VGD 0 0..0044 0 0..0044 0 0..0044 0 0..0044 0 0..0044 0 0..0044 CBT 0 0..0022 0 0..0022 0 0..0022 0 0..0022 0 0..0022 0 0..0022 -C1-BT 0.01 0.01 0.01 0.01 0.01 0.01 DEHA 0.02 0.02 0.02 0.02 0.02 0.02 TOTAL 100 100 100 100 100 100 SAMPLE, parts by weight Component É-Z M C-6A C-6B C-6C C-6D XPD-2470 65.7 65.7 65.7 65.7 65.7 65.7 TMPEOTA 18 30.4 12 18 18 30.4 SR9036 - - 9 6 - - NK Ester 9PG 6.4 - 6.4 6.4 6.4 - SR604 3 CD-541 6 - - - 6 EMK 0.06 0.06 0.06 0.06 0.06 0.06 OE-HABI 3 3 - - - - o-Cl-HABI - - 3 3 3 3 ITX 0.4 0.4 0.4 0.4 0.4 0.4 nPG 0.5 0.5 0.5 0.5 0.5 0.5 LCV 0.3 0.3 0.35 0.3 0.3 0.3 VGD 0.04 0.04 0.04 0.04 0.04 0.04 CBT 0.02 0.02 0.02 0.02 0.02 0.02 -C1-BT 0.01 0.01 0.01 0.01 0.01 0.01 DEHA 0.02 0.02 0.02 0.02 0.02 0.02 TOTAL 100 100 100 100 100 100 Solutions of 50% solids in acetone were coated to form films. The films were tested to verify mud formation and photographic speed. The results are given in the following table.

SAMPLE 6.1 Ll 6-3 6-4 6-5 frjí Mud 1 i 1 1 3 2 Photographic speed 40 mJ / cm2 24 21 SAMPLE Ll L C-6A C-6B C-6C C-6D > d0 2 2 8 8 6 6 Photographic speed 40 mJ / cm2 24 It is clear from the above data that there is a much greater mud formation in the compositions with the o-Cl-HABI.

Example 7 A cleaning solution is prepared by dissolving 15 g of potassium hydroxide in 1 liter of water. To this is added 1.5 ml of Pluronic \ 31R1 (BASF, Mt. Olive, NJ), which is a polyoxyethylene / polyoxypropylene copolymer plasticizer. A 30.5 X 30.5 cm (12 inches by 12 inches) sample of the processed, ie exposed and developed, photocurable film, which is 30.5 microns thick (1.2 mils), which represents 3.4 g of the photocurable substance, It is placed in 100 g of the developer solution and kept at a temperature of 50-55 ° C (120-130 ° F). The sample is allowed to settle until the processed photoresist sample has dissolved, and the amount of the precipitate is determined according to the same scale used for the samples in the developer solution. The photocurable films on copper FR-4 substrates were prepared using the compositions of Example 1, as described above. These are fully exposed to actinic radiation using the DuPont PC-530 exposure unit and then treated with the cleaning solution as described above. Samples that contain o-Cl-HABI have evaluations or training qualifications of sludge of 5-10, while samples containing the TCDM-HABI have evaluations or mud formation ratings of 0-3.

It is noted that in relation to this date the best method known by the applicant to carry out the aforementioned invention, is that which is clear from the present description of the invention.

Having described the invention as above, property is claimed as contained in the following

Claims (19)

1. A process for producing masks configured on substrates, the process is characterized in that it comprises the steps of: (a) applying a photoresistible substance that can be developed in aqueous phase to a surface of a first substrate, the photocurable substance comprises a photoinitiator; (b) guiding by images exposure to actinic radiation to produce exposed and unexposed areas in the photocurable substance; (c) treating the photo-hardenable substance exposed to the manner or by means of images with a sample of the aqueous alkaline solution, the solution contains less than 5% by weight of organic content, leading to the removal of the areas whether exposed or not exposed from the photohardenable substance; and (d) repeating steps (a) to (c) at least 5 times, wherein each repetition uses a new sample of photocurable substance and a new substrate and essentially the same sample of the aqueous alkaline solution; wherein the photoinitiator comprises at least one hexaarylbiimidazole compound having at least one hydrophilic group, and wherein the process produces less than 0.05 grams of slurry per 3 grams of the photocurable substance disclosed by 100 grams of the aqueous alkaline solution.

2. The process according to claim 1, characterized in that the photocurable substance comprises an ethylenically unsaturated compound, and a binder.

3. The process according to claim 1, characterized in that the hydrophilic group is selected from methoxy, ethoxy, hydroxy, dialkylamino, carboxyl, carboxylic ester, carboxyl amide, carboxyl salt, and mixtures thereof.

4. The process according to claim 1, characterized in that the hexaarylbiimidazole also has at least one chlorine substituent.

5. The process according to claim 1, characterized in that the photoinitiator is select from 2,2 ', 5-tris- (o-chlorophenyl) -4- (3,4-dimethoxyphenyl) -4', 5'-diphenyl-1,2-biimidazole, 2,2 ', 4,4' -tetra- (o-chlorophenyl) -5,5'-bis- (3, -dimethoxyphenyl) -biimidazole; 2,2'-bis- (o-chlorophenyl) -4,4 ', 5,5'-tetra- (m-methoxyphenyl) -1,2-biimidazole, and mixtures thereof.

6. The process according to claim 1, characterized in that the photoinitiator comprises a mixture of 2,4,5-triphenylimidazolyl dimers which are the product of 2- (o-chlorophenyl) -4,5-diphenylimidazole and 2,4 -bis- (o-chlorophenyl) -5- [3, 4-dimethoxyphenyl] -imidazole by the oxidant bond, a product of the reaction is 2,2 ', 5-tris- (o-chlorophenyl) -4- ( 3, 4-dimethoxyphenyl) -4 ', 5'-diphenyl-biimidazole.

7. The process according to claim 1, characterized in that the photocurable material further comprises a hydrogen donor compound.

8. The process according to claim 2, characterized in that the photoinitiator comprises 0.1-10% by weight, based on the total weight of the photocurable substance; the ethylenically unsaturated compound comprises 5-60% by weight, based on the weight total of the photohardenable substance; and the binder comprises 25-90% by weight, based on the total weight of the photocurable substance.

9. The process according to claim 8, characterized in that the photoinitiator comprises 0.5-3% by weight, based on the total weight of the photocurable substance.

10. A process to remove the templates or configurations of the processed photoprotective substance from the substrates, the process is characterized in that it comprises the steps of: (a) treating the photo-hardenable substance processed with a sample of a cleaning solution, leading to the removal of the substance processed photoresist; and (b) repeating step (a) at least 5 times, wherein each repetition uses a new substrate and processed photocurable substance and essentially the same sample of the cleaning solution; wherein the photocurable substance comprises at least one hexaarylbiimidazole compound having at least one hydrophilic group, and wherein the process produces less than 0.05 grams of mud per 3 grams of the substance photo-hard clean by 100 grams of cleaning solution.

11. The process according to claim 10, characterized in that the photocurable substance further comprises an ethylenically unsaturated compound, and a binder.

12. The process according to claim 10, characterized in that the hydrophilic group is selected from methoxy, ethoxy, hydroxy, dialkylamino, carboxyl, carboxylic ester, carboxyl amide, carboxyl salt, and mixtures thereof.

13. The process according to claim 10, characterized in that the hexaarylbiimidazole also has at least one chlorine substituent.

14. The process according to claim 10, characterized in that the photoinitiator is selected from 2, 2 ', 5-tris- (o-chlorophenyl) -4- (3,4-dimethoxyphenyl) -4', 5'-diphenyl-1. , 2-biimidazole, 2,2 ', 4,4'-tetra- (o-chlorophenyl) -5,5' -bis- (3, -dimethoxyphenyl) - biimidazole; 2,2'-bis- (o-chlorophenyl) -4,4 ', 5,5'-tetra- (m-methoxyphenyl) -1,2-biimidazole, and mixtures thereof.

15. The process according to claim 10, characterized in that the photoinitiator comprises a mixture of 2,4,5-trifemlimidazolyl dimers which are the product of 2- (o-chlorophenyl) -4,5-diphenylimidazole and 2,4 -bis- (o-chlorophenyl) -5- [3, 4-dimethoxyphenyl] -imidazole by the oxidant bond, a product of the reaction is 2,2 ', 5-tris- (o-chlorophenyl) -4- ( 3, 4-dimethoxyphenyl) -4 ', 5'-dipheny1-biimidazole.

16. The process according to claim 10, characterized in that the photocurable substance further comprises a hydrogen donor compound.

17. The process according to claim 11, characterized in that the photoinitiator comprises 0.1-10% by weight, based on the total weight of the photocurable substance; the ethylenically unsaturated compound comprises 5-60% by weight, based on the total weight of the photocurable substance; and the binder comprises 25-90% by weight, based on the total weight of the photocurable substance.

18. The process according to claim 17, characterized in that the photoinitiator comprises 0.5-3% by weight, based on the total weight of the photocurable substance.

19. The process according to claim 10, characterized in that the cleaning solution is an aqueous alkaline solution.