US3661575A - Gravure printing plate of photocurable material - Google Patents

Gravure printing plate of photocurable material Download PDF

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US3661575A
US3661575A US828A US3661575DA US3661575A US 3661575 A US3661575 A US 3661575A US 828 A US828 A US 828A US 3661575D A US3661575D A US 3661575DA US 3661575 A US3661575 A US 3661575A
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composition
per molecule
carbon
percent
actinic radiation
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Arthur D Ketley
Joseph A Cogliano
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WR Grace and Co Conn
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WR Grace and Co
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Assigned to W.R. GRACE & CO.-CONN. reassignment W.R. GRACE & CO.-CONN. MERGER (SEE DOCUMENT FOR DETAILS). EFFECTIVE DATE: MAY 25, 1988 CONNECTICUT Assignors: GRACE MERGER CORP., A CORP. OF CONN. (CHANGED TO), W.R. GRACE & CO., A CORP. OF CONN. (MERGED INTO)
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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F5/00—Screening processes; Screens therefor
    • G03F5/20—Screening processes; Screens therefor using screens for gravure printing
    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03F—PHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00—Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004—Photosensitive materials
    • G03F7/027—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds
    • G03F7/0275—Non-macromolecular photopolymerisable compounds having carbon-to-carbon double bonds, e.g. ethylenic compounds with dithiol or polysulfide compounds

Definitions

  • the printing cylinder is manufactured to a very high tolerance to allow control of web tension and color register, and it is chromium plated to prolong its working life. In addition, the cylinder is carefully balanced to avoid vibrations that would cause excessive wear.
  • the doctor blade is normally constructed of sheet steel and is mounted parallel to the cylinder and pressure may be applied if required. The angle of contact may be varied and during operation the blade is oscillated from side to side.
  • the web is printed by contact between the inked cylinder and a friction-driven rubbercovered impression roller.
  • the gravure process is capable of reproducing continuous tone pictures as well as line drawings and type images. It is distinguished from other processes in that all copy must be screened, both to separate the individual ink carrying cells and to form a bearing surface for the doctor blade.
  • the area of an individual cell is determined by the size of the screen used, which varies between l-300 lines per inch, usually 150 lines per inch in commercial workv Gravure enables tonal values to be produced in three ways:
  • the conventional half-tone methods produce different tones by utilizing a constant thickness of ink and different dot sizes as in two (2) supra.
  • Gravure processes l) and (3) supra in addition to using a variable dot size, enable an ink film of variable thickness to be applied by virtue of the cells of variable depth.
  • the capability of printing ink layers of variable thicknesses accounts for the superior quality of the gravure printing over the other major methods.
  • a rotogravure cylinder begins with the electroplating of a stell cylinder with a 0.040 inch thick layer of copper, which is subsequently machined and polished to the required diameter.
  • the Ballard process offers an alternative by using a thin 0.006 inch thick removable copper sleeve.
  • Photographically, conventional gravure requires continuous tone intermediates, the Henderson process requireshalf-tone intermediates and the Hurleton or mixed process requires both continuous and half-tone intermediates.
  • the intermediate transparencies are used to expose the photochemical resistance materials, which control the etching operation.
  • the resists usually carbon tissue or Dupont (Rotofilm) are hardened differentially and respond differentially to etchants of varying density.
  • the exposed resist is mounted on the cylinder, developed in hot water and rotated in the etching solution.
  • the etching process is a critical and time consuming operation, and up to six solutions (usually FeCl of different concentrations are used. It is usual to apply corrective reetching in local areas. If the cells are too shallow, the cylinder is either locally or completely re-etched. The top surface is carefully protected during this operation. Cells that are etched too deeply may be corrected by spot electroplating and the application of lacquer to the bottom of the cells. The proofed cylinder is finally electroplated with chromium with 0.0002 inch thick to minimize cylinder wear in long run work.
  • One object of the instant invention is to eliminate the laborious chemical etching process of present-day gravure plate making.
  • Another object of the instant invention is to substitute a photocurable material for the metal e.g, copper, gravure image carrier.
  • Another object is to prepare a photocurable polymer gravure printing plate in which the discrete gravure cells are produced by selective photocuring to replace the conventional method of preparation bychemical etching of copper through a selectively hardened resist.
  • Still another object is to prepare a photocurable gravure printing plate which requires no wet chemicals in the etching or development step.
  • this invention is directed to forming an image carrier for gravure printing comprising a photocurable composition i.e, a polyene, polythiol and photosensit'izer or curing rate accelerator which on exposure through.
  • a photocurable composition i.e, a polyene, polythiol and photosensit'izer or curing rate accelerator which on exposure through.
  • conventional screens and image-bearing transparencies can be readily etched or hardened to form a gravure image carrier on a cylinder.
  • the cylinder can be electroplated with chromium to minimize wear for long run workings. Any of the three aforesaid methods to obtain tonal values are operable by the use of the instant invention. For purposes of description tonal values by using cells of constant area but varying depth will be exemplified hereinafter unless otherwise noted.
  • photocurable composition means a composition having a viscosity in the range 0 to 20 million centipoises at C. which is solidified by photocuring on exposure to actinic light.
  • Photocurable systems which are operable in the instant invention are set out in copending applications having U.S. Ser. No. 674,773 filed Oct. 12, 1967 and U.S. Ser. No. 779,596 filed Nov. 27, i968 assigned to the same assignee and both incorporated by reference herein.
  • a composition consisting of a 2 to 98 parts by weight of a polyene containing atleast two unsaturated carbon to carbon bonds per molecule, '98 to 2 parts by weight of a polythiol containing two or more thiol groups per molecule, and a photocuring rate accelerator, i.e., a photosensitizer, e.g., benzophenone, is cured on exposure to UV light.
  • a photosensitizer e.g., benzophenone
  • polyenes and polyynes refer to a simple or complex species of alkenes of alkynes having a multiplicity, i.e., at least 2 reactivc" carbon to carbon unsaturated functional groups per average molecule.
  • a diene is a polyene that has two reactive" carbon to carbon double bonds per average molecule
  • a diyne is a polyyne that contains in its structure two reactive" carbon to carbon triple bonds per average molecule. Combinations of reactive" triple bonds within the same molecule are also operable.
  • An example of this is monovinylacetylene, which is a polyeneyne under our definition. For purposes of brevity all these classes of compounds will be referred to herein as polyenes.
  • reactive unsaturated carbon to carbon groups means groups which will react under proper conditions as set forth herein with thiol groups to yield the thioether linkage ascontrasted to the term unreactive carbon to carbon unsaturation which means groups when found in aromatic nucleii (cyclic structures exemplified by benzene, pyridine, anthracene and the like) which do not under the same conditions react with thiols to give thioether linkages.
  • products from the reaction of polyenes with polythiols which contain 2 or more thiol groups per average molecule are called polythioether polymers or polythioethers.
  • One group of polyenes operable in the instant invention to react with polythiols to form a gravure image carrier is that taught in a copending application having Ser. No. 617,801 filed Feb. 23, 1967, assigned to the same assigneeand incorporated herein be reference.
  • This group includes those having a molecular weight in the range 50 to 20,000 a viscosity ranging from to 20 million centipoises at 70 C.
  • X is a member ofthe group consisting of and R-C E C m is at least 2;
  • R is independently selected from the group consisting of hydrogen, halogen, aryl, substituted aryl, cycloalkyl, substituted cycloalkyl, aralkyl, substituted aralkyl and alkyl and substituted alkyl groups containing 1 to 16 carbon atoms and
  • A is a polyvalent organic moiety free of (l) reactive carbon to carbon unsaturation and (2) unsaturated groups in conjugation with the reactive ene or yne groups in X.
  • A may contain cyclic groupings and minor amounts of hetero atoms such as N, S, P or 0 but contains primarily carbon-carbon, carbon-oxygen or silicon-oxygen chain linkages without any reactive carbon to carbon unsaturation.
  • operable polyenes from this group include, but are not limited to,
  • a second group of polyenes operable in the instant invention as photocurable materials in combination with a polythiol and a photosensitizer includes unsaturated polymers in which the double or triple bonds occur primarily within the main chain of the molecules.
  • unsaturated polymers include conventional elastomers (derived primarily from standard diene monomers)-such as polyisoprene, polybutadiene, styrene-butadiene rubber, isobutylene-isoprene, polychloroprene, styrene-butadiene-acrylonitrile rubber and the like; unsaturated polyesters, polyamides, and polyurethanes derived from monomers containing freactive" unsaturation, e.g., adipic acid-butenediol, l,6-hexanediamine-fumaric acid and 2,4- tolylene diisocyanate-butenediol condensation polymerand the like.
  • a third group of polyenes operable in this invention, as photocurable materials in combination with a polythiol and a photosensitizer includes those polyenes in which the reactive unsaturated carbon to carbon bonds are conjugated with adjacent unsaturated groupings.
  • Examples of operable reactive conjugated ene systems include, but are not limited to, the following:
  • polymeric polyenes which contain conjugated reactive double bond groupings such as those described above are polyethyeleneether glycol diacrylate having a molecular weight of about 750, polytetramethylenether glycol dimethyacrylate having a molecular weight of about l,l75, the triacrylate of the reaction product of trimethylolpropane with 20 moles of ethylene oxide and the like.
  • polyenes include those materials which in the present of an inert solvent, aqueous dispersion or plasticizer fall within the viscosity range set out above at C.
  • polythiol refers to the simple or complex organic compounds having a multiplicity, i.e., at least 2, of pendant or terminally positioned -Sl-l functional groups per average molecule.
  • polythiols 0n the average the polythiols must contain 2 or more -SH groups/molecule. They usually have a viscosity range of 0 to 20 million centipoises (c.p.s.) at 130 C. as measured by a Brooktield viscometer. Included in the term polythiols as used herein are those materials which in the presence of an inert solvent, aqueous dispersion or plasticizer fall within the viscosity range set out above at 130 C. Operable polythiols in the instant invention usually have molecular weights in the range 5020,000, preferably loo-10,000.
  • polythiols operable in the instant invention can be emplified by the general formula:
  • R is a polyvalent organic moiety free from reactive" carbon to carbon unsaturation.
  • R may contain cyclic groupings and minor amounts of hetero atoms such as N, S, P or 0 but primarily contains carbon-hydrogen, carbon-oxygen, or silicon-oxygen containing chain linkages free of any reactive" carbon to carbon unsaturation.
  • esters of. thiol-containing acids of the general formula:
  • R is an organic rnoi e ty con faining no reactive car bon to carbon unsaturation and n is 2 or greater.
  • R and R are organic moieties containing no reactive carbon to carbon unsaturation and n is 2 or greater.
  • polythiols such as the aliphatic monomeric polythiols (ethane dithiol, hexamethylene dithiol, decamethylene dithiol, tolylene-2,4-dithiol, etc.) and some polymeric polythiols such as a thiol-terminated ethylcyclohexyl dimercaptan polymer, etc. and similar polythiols which are conveniently and ordinarily synthesized on a commercial basis although having obnoxious odors, are operable in this invention.
  • polythiols such as the aliphatic monomeric polythiols (ethane dithiol, hexamethylene dithiol, decamethylene dithiol, tolylene-2,4-dithiol, etc.) and some polymeric polythiols such as a thiol-terminated ethylcyclohexyl dimercaptan polymer, etc. and similar polythiol
  • polythiol compounds preferred for this invention because of their relatively low odor level and fast curing rate include, but are not limited to, esters of thioglycolic acid (HS-CH COOl-l), a-mercaptopropionic acid (HS- CH(Cl-l -,)-COOH) and B -mercaptopropionic acid (HS- CH CH COOl-l) with polyhydroxy compounds such as glycols, triols, tetraols, pentaols, hexaols, etc.
  • esters of thioglycolic acid HS-CH COOl-l
  • a-mercaptopropionic acid HS- CH(Cl-l -,)-COOH
  • B -mercaptopropionic acid HS- CH CH COOl-l
  • polyhydroxy compounds such as glycols, triols, tetraols, pentaols, hexaols, etc.
  • polythiols include, but are not limited to, ethylene glycol bis (thioglycolate), ethylene glycol bis (B mercaptopropionate), trimethylolpropane tris (thioglycolate), trimethylolpropane tris (B -mercaptopropionate), pentaerythritol tetrakis (thioglycolate) and pentaerythritol tetrakis (B -mercaptopropionate), all of which are commercially available.
  • polypropyleneether glycol bis ([3 -mercaptopropionate) which is prepared from polypropyleneether glycol (e.g., Pluracol P2010, Wyandotte Chemical Corp.) and B -mercaptopropionic acid by esterification.
  • the preferred polythiol compounds are characterized by a low level of mercaptan-like odor initially, and after reaction give essentially odorless cured polythioether end products which are commercially useful resins or elastomers for a gravure image carrier.
  • functionality refers to the average number of ene or thiol groups per molecule in the polyene or polythiol, respectively.
  • a triene is a polyene with an average of three reactive carbon to carbon unsaturated groups per molecule and thus has a functionality (j) of three.
  • a dithiol is a polythiol with an average of two thiol groups per molecule and thus has a functionality (I) of two.
  • the functionality of the polyene and the polythiol component is commonly expressed in whole numbers although in practice the actual functionality may be fractional.
  • a polyene component having a nominal functionality of 2 may in fact have an effective functionality of somewhat less than 2.
  • the functionality (assuming 100 percent pure starting materials) would be 2.0.
  • the reaction were carried to only 95 percent of theory for complete reaction, about 10 percent of the molecules present would have only one ene functional group, and there may be a trace of material that would have no ene functional groups at all.
  • Such a product is useful in the instant invention and is referred to herein as having a functionality of 2.
  • polyenes and polythiols can, if desired, be formed or generated in situ and still fall within the scope of the instant invention.
  • the reaction components consisting of the polyenes and polythiols of this invention are formulated in such a manner as to give solid, crosslinked three dimensional network polythioether polymer systems on curing.
  • the individual polyenes and polythiols must each have a functionality of at least 2 and the sum of the functionalities of the polyene and polythiol components must always be greater than 4. Blends and mixtures of the polyenes and the polythiols containing said functionality are also operable herein.
  • the polythiol and the polyene compounds in such amounts that there is one thiol group present for each ene group, it being understood that the total functionality of the system must be greater than four, and the functionality of the thiol and the diene must each be at least two. For example, if two moles of a triene are used, and a dithiol is used as the curing agent, making the total functionality have a value of five, it is preferable to use three moles of the dithiol.
  • the curing rate will be lower and the product will be weaker in some respects because of the reduced crosslink density. lf much more than the stoichiometric amount of the thiol is used, the rate of cure may be higher, if that is desirable, although excessive amounts can lead to a plasticized crosslinked product which may not have the desired properties.
  • One method of employing the photocurable composition of this invention as a gravure image carrier involves exposing through a suitable screen a uniformly thick layer of the photocurable composition sandwiched between two films at least one of which transmits actinic radiation. It is also possible to merely have the photocurable composition on one substrate which transmits actinic radiation without the necessity for a top layer, especially when the photocurable composition is highly viscous. In this instance, the substrate transmits actinic radiation and the exposure to UV light is through the substrate. The system is exposed to collimated UV light for sufficient time to allow photocuring of the exposed areas to take place throughout the thickness of the photocurable layer. This exposure results in the formation of discrete cells of uncured photocurable material separated by cell walls of solidified photocured material.
  • the screen is replaced with a screenless, continuous tone, image-bearing positive transparency and the photocurable layer is reexposed through the transparency for sufficient time to cause the tonal range of the positive to be reproduced by selectively curing the photocurable material to a solid of variable depths.
  • Exposure of the photosensitizable material to UV light causes the photosensitizable material to adhere to the film proximate the actinic radiation light source.
  • the other film away from the light source is peeled off the photocurable material and the remaining uncured portion of the photocurable layer is removed by dissolution in a solvent for the photocurable material leaving discrete cells of varying depth for printing.
  • Another method of using the photocurable composition of the instant invention for forming a gravure plate is to employ a metal shell containing a grid system whose holes extend partially or completely through the entire shell said shell being easily removable from a metal printing roller or cylinder.
  • the holes in the shell are filled with the photocurable composition and the image placed on the grid by either of the following systems:
  • the outside surface is covered with a U.V. transparent film to which cured'photocurable composition adheres over which is positioned a continuous tone, negative transparency of the image.
  • the negative is removed, the UV transparent film and adhering photocured composition is stripped from the shell and the residual photocurable composition in the grid is reexposed to UV collimated light to cure and harden same and form a gravure image carrier for printing.
  • a third method of employing a photocurable composition to make an image carrier for gravure printing by the instant invention has the added advantage that no wet chemicals are needed for the preparation of the plates and that they require only a UV light source.
  • This dry process method comprises etching a gravure plate or cylinder with a grid work to provide a multitude of cells and lands. The cells are filled with the photocurable composition and then covered with a 'U.V transparent film so that contact is made with the surface of the photocurable material. Acontinuous, image-bearing,negative transparency is placed in contact with the film and exposed to collimated UV light. The negative is removed and the film together with adhering cured portion of the photocurable material is stripped off from the surface of the plate or cylinder.
  • the residual photocurable material is then reexposed to collimated UV light to cause the composition to solidify by curing.
  • the amount of photocurable material which remains in the cells after stripping off the film with the adhering cured portion of the photocurable material is proportional to the amount of light passing through the negative.
  • a clear portion of the negative will allow light to cure most of the photocurable material beneath it which will be removed with the film leaving no photocurable material in the cell.
  • This cell will be completely filled with ink during the printing process producing a very black impression.
  • a dark portion of the negative will produce a white portion during the printing. Gray areas will result in varying depths of residual photocurable material and hence proportional ink pick-up.
  • the plates can be reused by soaking in a solvent in which the cured polymer is partially or completely soluble.
  • The-surface can be wiped clean without damage to the original grid system.
  • a photocurable composition comprising 10 parts by weight of Prepolymer B from Example 2, 8.5 parts of pentaery-thritol tetrakis (B -mercaptopropionate) commercially available from Carlisle Chemical Co. under the tradename Q-43 and 0.015 parts of dibenzosuberone were admixed together. The mixture was degassed by heating at 70 C. under vacuum and cast into a painted black glass mold 4 X 3 X 0.037. Sufficient volume was used to fill the mold and a thin film of polyvinyl alcohol (1 ml. thick) was stretched and held in contact with the mixture.
  • a screen containing 40 lines per inch and a transparent/opaque ratio of 1:2.33 was placed with the emulsion side in contact with the polyvinyl alcohol film.
  • the system was mounted in a vacuum table to provide intimate contact and exposed through the screen to UV light from an Ascorlux lamp providing a surface intensity of 2,500 microwatts/cm. for 4 minutes.
  • the screen was removed and the procedure was repeated with a continuous tone, image bearing, positive transparency for an exposure period of 2 and minutes.
  • the resulting plate with the polyvinyl alcohol backing layer was removed from the mold, washed in ultrasonically agitated ethanol for 5 minutes and post-exposed to the same lamp with the same intensity for 7 minutes on each side to harden it.
  • the flexible gravure plate was mounted on a 2% inch diameter roller using a proprietory adhesive.
  • a doctor blade was constructed from rubber (Shore A Hardness 80), chamfered to an edge and mounted between metal plates. This assembly was held at 80 to the printing plate with the sharp rubber edge in intimate contact with the plate surface.
  • the plate roller was continually rotated in a bath of gravure printing ink, (Sinclair and Valentine vinyl black no 3.) mounted underneath.
  • a white paper web 3% inches wide passed through the nip formed between the plate and a 2% inch diameter rubber covered impression roller.
  • the paper roll was maintained in tension and was contained 150 lines per inch and a ratio of space to line of 2.5 to l. The resultant prints were of good quality.
  • a copper cylinder was etched by conventional means after being exposed through a screen with 150 lines to the inch in a ratio of space to line of 2% to l.
  • a photocurable mixture consisting of 10 parts of prepolymer A from Example 1, parts of pentaerythritol tetrakis (B -mercaptopropionate) and 0.2 parts benzophenone were admixed together and degassed by heating at 70 C. under vacuum.
  • the wells of the etched cylinder were then filled with the photocurable mixture and covered with a UV transparent cellulose acetate film (1 mil thick) so that contact is made with the surface of the photocurable material.
  • a continuous-tone,image-bearing, negative transparency was placed in contact with the cellulose acetate film and exposed to UV light from an Ascorlux lamp providing a surface intensity of 25,000 microwatts/centimeter 2 for 3 minutes.
  • the negative was removed and the cellulose acetate film together with the photocured portion of the photocurable material was stripped from the cylinder.
  • the residual uncured portion of the photocurable material was then exposed to light from the same light source at the same intensity for a period of 5 minutes to form cells of varying depth.
  • the use of the thus formed gravured cylinder in a conventional gravure press resulted in prints of excellent quality.
  • Example 6 was repeated except that Prepolymer A was replaced with 2.7 grams of the triacrylate of the reaction product of trimethylol propane with 20 moles of ethylene oxide. The resulting prints were of good quality.
  • EXAMPLE 9 A copper cylinder (3 mil thick) was etched clear through by conventional means after exposure through a screen with 150 lines to the inch and a ratio of space to line of 2.5 to l.
  • the cells in the cylinder were filled with a photocurable mixture comprising 10 parts of prepolymer C from Example 3, 8.2 parts of pentaerythritol tetrakis 3 -mercaptopropionate) and 0.02 parts dibenzosuberone which mixture had previously been degassed by heating at 70 C. under vacuum. Since the cells extended through the copper cylinder, a continuous tone image-bearing positive transparency was placed inside the cylinder proximate its surface and exposed to UV light from an Ascorlux lamp providing a a surface intensity of 25,000 microwatts/cm.
  • EXAMPLE 10 A copper cylinder (25 mil thick) was etched to a depth of 2.5 mils by conventional means after being exposed through a screen with 150 lines to the inch in a ratio of space to line of 2.5 to l. The etched cylinder was placed on a metal roller and the cells in the cylinder were filled with a photocurable material consisting of 10 parts by weight of Prepolymer B from Example 2, 25 parts of pentraerythritol tetrakis (B -mercaptopropionate) and 0.015 parts of dibenzosuberone which had previously been degassed by heating at 70 C. under vacuum.
  • a 1 mil thick film of cellulose acetate was placed over the cylinder in contact with the photocurable material and a continuous tone, image-bearing, negative transparency was placed on top of the cellulose acetate film.
  • the system was exposed through the transparency to UV light from an Ascorlux lamp providing a surface intensity of 25,000 microwatts/cm. for 5 minutes. After exposure, the negative was removed and the cellulose acetate film along with the adhering photocured material was stripped off the cylinder. The residual uncured portion of the photocurable material in the cylinder was then reexposed to UV light from the same light source and intensity for a period of 5 minutes to form a gravure image carrier. Prints resulting from the use of said image-carrier on a roller were of good quality.
  • the photocurable compositions of this invention are especially useful in producing gravure printing plates after exposure through conventional screens and continuous tone negative orpositive image-bearing transparencies.
  • the methods herein are especially useful since the exposure and subsequent development or etching can be carried out on the same or different side of the plate as desired.
  • the photocurable compositions to be converted to solid gravure printing plates may, if desired, include such additives as antioxidants, accelerators, dyes, inhibitors, activators, fillers, pigments, antistatic agents, flame etardant agents, thickeners, thixotropic agents, surface-active agents, light scattering agents, viscosity modifiers, extending oils, plasticizers, tackifiers and the like within the scope of this invention.
  • additives are usually preblended with the polyene or polythiol prior to or during the compounding or admixture step. Additives, however, should not be substantially opaque when present in the photocurable compositions.
  • the aforesaid additives may be present in quantities up to 500 parts or more per parts of the photocurable composition by weight and preferably 0.005-300 parts on the same basis, but each additive must be present in an amount which will not interfere with or inhibit the necessary photocuring reaction or other required steps in the process.
  • the support to which the photocured composition adheres is preferably a plastic having the characteristics of being flexible, adherable to the photocurable composition on exposure to UV radiation or by other means and can transmit a substantial amount of UV light.
  • Operable plastics include but are not limited to, polyethylene, polypropylene, poly-4-methylpentene, polystyrene, Mylar" i.e., polyethylene terephthalate, cellulose acetate and the like.
  • the thickness of the support is dependent on its relative strength and dimensional stability to hold a specified thickness of the photocurable composition and can be empirically determined by one skilled in the art. Support films usually have a thickness of about 0.5 to 10 mils.
  • the photocuring reaction can be initiated by actinic radiation from sunlight or from special light sources which emit significant amounts of actinic light suitably in the wave-length range of 2,2004,000A.
  • actinic radiation from sunlight or from special light sources which emit significant amounts of actinic light suitably in the wave-length range of 2,2004,000A.
  • the photocuring reaction rate can be increased by the use of a photosensitizer.
  • a photosensitizer means a curing rate accelerator as used in a curing reaction.
  • Various photosensitizers are operable and well known to those skilled in the art. Examples of photosensitizers include, but are not limited to, benzophenone, acetophenone, acenapthene-quinone, methyl ethyl ketone, valerophenone, hexanophenone, 'y
  • phenylbutyrophenone p-morpholinopropiophenone, dibenzosuberone, 4-morpholinobenzophenone, 4 morpholinodeoxybenzoin, p-diacetylbenzene, 4-
  • the photosensitizers iLe., curing rate accelerators are usually added in an amount ranging from 0.0005 to 50 percent by weight, suitably 0.0005 to 33% by weight, preferably 0.5 to percent, of the photocurable composition in the instant invention.
  • the compounding of the components 'of the photocurable composition prior to exposure to UV radiation can be carried out in several ways.
  • the polyene, the polythiol and any other additives e.g., photosensitizer
  • the polyene, the polythiol and any other additives are admixed in an inert atmosphere and charged to an aerosol can, drum, tube, or cartridge for subsequent use. Exposureof said admixed components to actinic radiation under ambient or elevated temperature conditions will initiate photocuring.
  • Another useful method of compounding the photocurable composition is to prepare by conventional mixing techniques but in the absence of actinic radiation a composition consisting of polyene, antioxidant (to inhibit spontaneous oxygen-initiated curing), polythiol, UV sensitizer, and other inert additives.
  • This composition generally can be stored in closed containers in the dark for extended periods of time, but on exposure to actinic radiation e.g, ultraviolet light, sunlight, etc.) will cure controllably and in a very short time period to solid polythioether suitable as gravure printing plates.
  • Conventional curing inhibitors or retarders operable with the photocurable compositions in the instant invention when desired include, but are not limited to, hydroquinone; p-tertbutyl catechol; 2,6-ditert-butyl-p-methylphenol; phenothiazine and N-phenyl-Zmapthylamine.
  • the molecular weight of the polyenes of the instant invention can be measured by various conventional methods including solution viscosity, osmotic pressure and gel permeation chromatography. Additionally, the molecular weight can be sometimes calculated from the known molecular weight of the reactants.
  • the viscosity of the polyenes and polythiols was measured on a Brookfield Viscometer at temperatures up to l C. in accord with the instructions therefor.
  • the thickness of the photocurable composition layer that is converted to solid polymer is proportional to the intensity of the light that strikes it. Consequently, when exposed under a continuous tone negative, clear areas in the negative will correspond to thick areas of cured polymer, very dense areas in the negative to substantially no polymer and intermediate densities to intermediate thicknesses of polymer. 7
  • a process for forming a gravure printing plate which comprises supporting a substantially uniformly thick layer of a composition consisting essentially of (l) 98 to 2 percent byv weight of said composition of a polyene containing at least 2 reactive unsaturated carbon to carbon bonds per molecule, (2) 2 to 98 percent by weight of said composition of a polythiol containing at least 2 thiol groups per molecule, the total combined functionality of (a) the reactive unsaturated carbon to carbon bonds per molecule in the polyene and (b) the thiol groups per molecule in the polythiol being greater than 4, and (3) 0.0005 to 50 percent by weight of said composition of a'photosensitizer, on a support film which is transparent to actinic radiation, exposing said composition to ac- .tinic radiation through the support film firstly through a conventionally gravure screen and secondly through an imagebearing, continuous tone positive transparency, said screen and said transparency being maintained adjacent to the support film and substantially parallel to the layer of said coinposition
  • a process for forming a gravure printing plate which comprises filling the cells of a metal cylinder shell which has been grid-etched through its thickness with a composition consisting essentially of l) 98 to 2 percent by weight of said composition of a polyene containing at least 2 reactive unsaturated carbon to carbon bonds per molecule, (2) 2 to 98 percent by weight of said composition of a polythiol containing at least 2 thiol groups per molecule, the total combined functionality of (a) the reactive uncured carbon to carbon bonds per molecule in the polyene and (b) the thiol groups per molecule in the polythiol being greater than 4, and (3) 0.0005 to 50 percent by weight of said composition of a photosensitizer, exposing said composition on the inside of the shell to actinic radiation through an image-bearing, continuous tone, positive transparency thereby causing portions of the composition exposed to actinic radiation to form a solidified cured reverse image relative to said transparency and thereafter removing uncured portions of the composition on the outside of the shell to form

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Printing Plates And Materials Therefor (AREA)
  • Manufacture Or Reproduction Of Printing Formes (AREA)
US828A 1970-01-05 1970-01-05 Gravure printing plate of photocurable material Expired - Lifetime US3661575A (en)

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Cited By (17)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
DE2501046A1 (de) * 1974-01-14 1975-07-17 Nippon Paint Co Ltd Verfahren zur herstellung von bildplatten und tiefdruckformen
US4046071A (en) * 1974-09-26 1977-09-06 Asahi Kasei Kogyo Kabushiki Kaisha Relief printing plate having projections in non-image areas
US4076535A (en) * 1973-12-03 1978-02-28 Carnation Company Method of preparing screens for screen printing
US4266007A (en) * 1978-06-22 1981-05-05 Hercules Incorporated Multilayer printing plates and process for making same
US4332873A (en) * 1979-08-22 1982-06-01 Hercules Incorporated Multilayer printing plates and process for making same
US4368587A (en) * 1979-04-20 1983-01-18 Bernard Childs Method of making color separation plates used as a proof and a positive for making offset printing plates photographically
US4383759A (en) * 1980-06-23 1983-05-17 Hercules Incorporated Method and apparatus for producing a capped printing plate
US4403566A (en) * 1980-06-23 1983-09-13 Hercules Incorporated Apparatus for producing a printing plate
US4450226A (en) * 1981-10-26 1984-05-22 Hercules Incorporated Method and apparatus for producing a printing plate
US4475810A (en) * 1980-10-06 1984-10-09 Hercules Incorporated Docking sensor system
US5213949A (en) * 1986-11-12 1993-05-25 Asahi Kasei Kogyo Kabushiki Kaisha Method for selectively curing a liquid photosensitive resin by masking exposure
US5698373A (en) * 1988-09-22 1997-12-16 Toray Industries, Incorporated Photosensitive relief printing plate and photosensitive intaglio printing plate
US5753414A (en) * 1995-10-02 1998-05-19 Macdermid Imaging Technology, Inc. Photopolymer plate having a peelable substrate
US6070528A (en) * 1996-06-19 2000-06-06 Man Roland Druckmaschinen Ag Process and device for gravure printing with an erasable gravure form
US20060084008A1 (en) * 2004-10-14 2006-04-20 Donald Long Compressible flexographic printing plate construction
WO2012003051A1 (en) 2010-07-02 2012-01-05 Macdermid Printing Solutions, Llc Multi-layer compressible foam sheet and method of making the same
US20150113801A1 (en) * 2013-10-28 2015-04-30 Murata Manufacturing Co., Ltd. Method for manufacturing gravure plate, gravure printing method, and method for manufacturing electronic component

Families Citing this family (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS61104886A (ja) * 1984-10-29 1986-05-23 Daiichi Kikai Service Kk 印刷方法
US6631676B2 (en) 1995-02-07 2003-10-14 Man Roland Druckmaschinen Ag Process and apparatus for gravure
DE19503951C2 (de) * 1995-02-07 1998-04-09 Roland Man Druckmasch Verfahren und Vorrichtung für den Tiefdruck

Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3055758A (en) * 1958-01-16 1962-09-25 Du Pont Production of direct positive images and light sensitive element therefor

Patent Citations (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US3055758A (en) * 1958-01-16 1962-09-25 Du Pont Production of direct positive images and light sensitive element therefor

Cited By (21)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US4076535A (en) * 1973-12-03 1978-02-28 Carnation Company Method of preparing screens for screen printing
DE2501046A1 (de) * 1974-01-14 1975-07-17 Nippon Paint Co Ltd Verfahren zur herstellung von bildplatten und tiefdruckformen
US4046071A (en) * 1974-09-26 1977-09-06 Asahi Kasei Kogyo Kabushiki Kaisha Relief printing plate having projections in non-image areas
US4266007A (en) * 1978-06-22 1981-05-05 Hercules Incorporated Multilayer printing plates and process for making same
US4368587A (en) * 1979-04-20 1983-01-18 Bernard Childs Method of making color separation plates used as a proof and a positive for making offset printing plates photographically
US4332873A (en) * 1979-08-22 1982-06-01 Hercules Incorporated Multilayer printing plates and process for making same
US4383759A (en) * 1980-06-23 1983-05-17 Hercules Incorporated Method and apparatus for producing a capped printing plate
US4403566A (en) * 1980-06-23 1983-09-13 Hercules Incorporated Apparatus for producing a printing plate
US4475810A (en) * 1980-10-06 1984-10-09 Hercules Incorporated Docking sensor system
US4450226A (en) * 1981-10-26 1984-05-22 Hercules Incorporated Method and apparatus for producing a printing plate
US5213949A (en) * 1986-11-12 1993-05-25 Asahi Kasei Kogyo Kabushiki Kaisha Method for selectively curing a liquid photosensitive resin by masking exposure
US5698373A (en) * 1988-09-22 1997-12-16 Toray Industries, Incorporated Photosensitive relief printing plate and photosensitive intaglio printing plate
US5753414A (en) * 1995-10-02 1998-05-19 Macdermid Imaging Technology, Inc. Photopolymer plate having a peelable substrate
US6070528A (en) * 1996-06-19 2000-06-06 Man Roland Druckmaschinen Ag Process and device for gravure printing with an erasable gravure form
US20060084008A1 (en) * 2004-10-14 2006-04-20 Donald Long Compressible flexographic printing plate construction
US7318994B2 (en) 2004-10-14 2008-01-15 Donald Long Compressible flexographic printing plate construction
US20080107908A1 (en) * 2004-10-14 2008-05-08 Macdermid Printing Solutions, Llc Compressible flexographic printing plate construction
US8071269B2 (en) 2004-10-14 2011-12-06 Donald Long Compressible flexographic printing plate construction
WO2012003051A1 (en) 2010-07-02 2012-01-05 Macdermid Printing Solutions, Llc Multi-layer compressible foam sheet and method of making the same
US20150113801A1 (en) * 2013-10-28 2015-04-30 Murata Manufacturing Co., Ltd. Method for manufacturing gravure plate, gravure printing method, and method for manufacturing electronic component
US9757970B2 (en) * 2013-10-28 2017-09-12 Murata Manufacturing Co., Ltd. Method for manufacturing gravure plate

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Publication number Publication date
FR2075204A5 (enExample) 1971-10-08
DE2100031A1 (de) 1971-07-15
AU2209070A (en) 1972-05-18

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