Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B41—PRINTING; LINING MACHINES; TYPEWRITERS; STAMPS
  • B41N—PRINTING PLATES OR FOILS; MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
  • B41N3/00—Preparing for use and conserving printing surfaces
  • B41N3/03—Chemical or electrical pretreatment
  • B41N3/038—Treatment with a chromium compound, a silicon compound, a phophorus compound or a compound of a metal of group IVB; Hydrophilic coatings obtained by hydrolysis of organometallic compounds

Definitions

• aiplate with alight sensitive coating is "exposed tolight through anegative, and the' image portion-ofuthe plate becomeshardened and madeinsoluble in waterbythe action ofthe light.
• the unexposed light-sensitive coating is "then removed by a desensitizing solution leaving awater-receptive or hydro- :philic underc'oating as thenon image area.
• siliceous hydrophilic underc'oating raises certain problems which have'beenovercome by the present invention.
• a silicated plate often has limited shelf life and limited water-receptivity. It may also tend to absorb moisture giving it a lack of stability in moist, warm atmospheres, thereby creating packaging and storing problems under these conditions.
• a silicate coating can often result in a-plate in which the number of true-copies which-can bemade are limited.
• a presensitized metal baseplanographic printingqplate may be made which does notinvolve the problems arising from the use of a silicate undercoating. This is accomplished by treating the metallic surface with-an aqueous solution of a zirconium hexahalide, preferably potassium zirconium fluoride.
• Another-object of this :invention isto provide -a-:presensitized aluminum plate havinganovel'hydrophilic coating which readily adheres to thealuminum, tenaciously holds an overlying light-sensitive material and is highly water receptive.
• I 7 V Another object of-tlais invention is'to provide -a presensitizedplate which, by virtue of-its novel-hydrophilic coating has long shelf life and provides" long runs of clear, detailed images.
• Still another object of this invention is to? provide a noveland economical methodforpreparinga plate having such characteristics.
• the present' invention involves a planegraphic. printing :plate con'iprising a -metallic base, -'a "hydrophilic coating thereonp'rovidedby treatment with an aqueous-solution of a zirconium hexahalide and a lightsensitive surface coating. 7 V
• this invention involves the preparation of an aluminum base plate: by treatmentwith an aqueous solutionof potassium zirconium fluoride .(K ZrE which reacts with-the surface ofthe-aluminum to .give a highly “desirable and permanently 'hydrophilic; coating to which -a light-sensitive material, such as a diazo resin, will tenaeiously adhere.
• the .present invention has *be'en found --th-at when one -or both surfaces of -a sheet of aluminum, after being degreased and,.preferably acidetched and cleaned, is imrnersedinto an aqueous solution of. potassium zirconium fluoride, the sur ace becomes hydrophilic and receptive to a light-sensitivadyeor resin, and that an image may .be providedon'thesurfaceby exposure ofselectedportions thereof to 'light.
• the light-altered dye preferably a diazo resin, forms 'a'per-man'ent image.
• the unconverted light-sensitive material is removed by a .desensitizer, and the almost invisible image 'is then developed by means of a suitable lacquer. Fhe resulting image is strong and holds tightly-to the:plalte.
• The'plate can then be placed on -a pressand a large number of copies made.
• the treatment with potassium zirconium fluoride is preferably followed by -a hot 'watertreatment which' appears to complete the chemical reaction between the K ZIF and the surface of the aluminum. While th'is treatment can take place within various limits 'kif' t-iine, temperature and concentration, the concentration of K Zr-F should generally "be between 'ilil iperc'ent, by weight, and a saturated solution (about 8:7 viper'cnt at 60 C.). It is particularly preferred that -theconcentration be between about-0.3 to 1.0 percent.
• the time of immersion may vary from-as little asrt'wo secondsto as much as ten minutes. Generally, a one to three minute interval is preferred for optimum'-1:fro essing economies.
• the 'temerature may vary between limits of about from 90 F. and 160 F. with favorable results being obtained at a temperature of 150 F. Naturally, temperature, time and concentration are interrelated and various combinations within theranges her in set forth can be effectively utilized.
• the hot water treatment which follows the immersion of the aluminum K ZrF involves the use of water at elevated temperatures between about 100 and 190 F.
• the temperature varies with the time of immersion which may be between about one and five minutes. It has been found that good results are obtained with a water temperature of about 150 F. and an immersion time of about between one and three minutes.
• the resulting coating or layer is in the form of a continuous film, as distinguished from crypto-crystalline zirconia particles which have been formed on plates of the prior art.
• the clean aluminum surface which is exposed to the K ZrF forms a reaction product of K A1F and K ZrF It is preferred that prior to this treatment, the surface of the aluminum be activated by chemical etching with various acids so that a more strongly adhering image can be obtained.
• the pretreatment of the aluminum will preferably involve not only an alkali degreasing agent, an acid etch, and a desmutting operation, but also a pre-treatment with an acid such as phosphoric acid, chromic acid, nitric acid, sulphuric acid or oxalic acid which activates the aluminum surface, and makes it more receptive to the subsequent treatment with aqueous K ZrF
• an acid such as phosphoric acid, chromic acid, nitric acid, sulphuric acid or oxalic acid which activates the aluminum surface
• the time of immersion may also vary between about one second and three minutes with five to ten seconds giving good results, depending on the concentration and time.
• the temperature can also vary between about 50 F. and 100 F. with 65 F. providing a suitable treatment. It should be noted that, here also time, temperature and concentration are all inter-related and various combinations within the limits stated can be used. There is some danger in having the concentration of the acid too high because, under these conditions, a pitting of the plate may take place. Some acids, such as sulphuric acid, which tend to attack aluminum faster, would be utilized at lower temperatures and for shorter contact times in obtaining optimum results.
• the hydrophilic surface may then be hardened in a bath of a watersoluble organic acid,- such as citric or tartaric acid and preferably citric acid.
• a watersoluble organic acid such as citric or tartaric acid and preferably citric acid.
• the plate may be clipped in a dilute solution of citric acid of preferably between about 0.1 percent to 5 percent, by weight, and the temperature between about 50 F. and 100 F., the time of immersion varying between about one second and five minutes.
• the metallic base which is preferably aluminum is prepared for the silicate treatment either by etching the same with acid and alkali or by graining. Typical acid-etching treatments are known to the prior art and, for example, described in detail in U.S. Patent No. 2,882,153.
• the graining may be performed by any of the mechanical means well known in the art, e.g. by rubbing with an abrasive, sandblasting or brushing with a wire, nylon, or hair brush. Details of mechanical graining methods are found in the prior art, e.g. see U.S. Patent No. 2,882,154.
• the hydrophilic coating is on the plate, there may be applied thereto various light-sensitive compounds.
• the plate is to be of the type in which the lithographer applies the light-sensitive material, such material would be, for example, albumen bichromate.
• the light-sensitive material typically would be one of the well known diazo resins which have been found, upon exposure to ultra-violet light, to be sufficiently light-hardenable to be useful in planographic printing processes.
• a typical compound as previously mentioned is the condensation product of paraformaldehyde and paradiazodiphenylamine.
• the sensitizer may comprise one percent diazo and 0.1 percent of a 10 percent solution of saponin.
• the hydroquinone may be applied as a .01 to 0.1 percent aqueous solution.
• a sheet of 38 aluminum (99 percent purity) is degreased, etched, and rinsed with water in accordance with well known techniques. It is then dipped in 0.2 percent phosphoric acid, by weight, for five to ten seconds at a temperature of 65 F. The plate is then removed from the bath, permitted to drain for a minute and then immersed in a solution of 1 percent potassium zirconium fluoride at about 150 F. for a period of three minutes. The above procedure may also be performed using 0.5 percent oxalic acid, instead of the phosphoric acid.
• the aluminum sheet is then removed from this bath and permitted to drain for one minute. It is then immersed in hot water at about 150 F. for three minutes.
• the plate is then removed from the hot water and permitted to drain for one minute, and then immersed in a one percent solution of a citric acid at 65 F. forthree minutes.
• the plate is then removed from the citric acid solution, rinsed with water, dried, and a solution of a light-sensitive dye is applied to both sides of the aluminum sheet.
• the light-sensitive material is the condensation product of paraformaldehyde and paradiazodiphenylamine (four parts of formaldehyde to thirty parts of paradiazodiphenylamine, by weight).
• the plate is coated on both sides, retaining about 0.25 cc. of diazo solution per side. After drying the plate is ready for use.
• the plate may be subjected to vigorous testing, and upon removal and redeveloping of the image five times, the plate is put on the printing press and 2,500 sharp and clear copies are run.
• a presensitized planographic printing plate comprising a metallic base and a hydrophilic coating thereon in the form of a continuous film, said coating being provided by treatment of the metal base with an aqueous solution of a zirconium hexahalide, and a light sensitive diazo coating overlying said hydrophilic coating.
• a presensitized planographic printing plate comprising an aluminum base, a hydrophilic coating thereon in the form of a continuous film, said coating being provided by treatment of the aluminum base with an aqueous solution of K ZrF and a light-sensitive diazo coating, overlying said hydrophilic coating.
• a presensitized planographic printing plate comprising an acid treated aluminum base and a hydrophilic coating thereon in the form of a continuous film, said coating being provided by treatment of the aluminum base with an aqueous solution of a zirconium hexahalide and a light sensitive diazo coating overlying said hydrophilic coating.
• a presensitized planographic printing plate comprising an aluminum base, a hydrophilic coating thereon in the form of a continuous film, said coating being provided by treatment of the aluminum base with an aqueous solution of a zirconium hexahalide and a light-sensitive diazo surface coating overlying said hydrophilic coating.
• the method of preparing a presensitized metallic base planographic printing plate comprising treating the metallic surface with an aqueous solution of a zirconium hexahalide so as to form a hydrophilic surface thereon and then coating said hydrophilic surface with a lightsensitive diazo compound.
• the methodof claim 9 in which the surface of the aluminum is acid etched by pre-treatrnent with phosphoric acid prior to the treatment with K ZrF 11.
• the method of preparing a presensitized aluminum base planographic printing plate comprising treating the aluminum surface with an aqueous solution of K ZrF at elevated temperatures so as to form thereon a hydrophilic 13.
• the method of preparing an aluminum base plane graphic printing plate comprising treating at least one surface of a sheet of degreased aluminum with an aqueous solution of an acid from the group consisting.
• the method of preparing an aluminum base planegraphic printing plate comprising treating at least one surface of a sheet of degreased aluminum with an aquesurface, hardening said surface with a citric acid treatment, and then coating said hydrophilic surface with a light-sensitive diazo compound.
• the method of preparing an aluminum base pianographic printing plate comprising treating at least one surface of a sheet of degreased aluminum with an aqueous solution of an acid from the group consisting of phosphoric and oxalic acids and then rendering said acidtreated surface hydrophilic by a subsequent treatment withan aqueous solution of K ZrF at elevated temperatures and then applying to said plate an aqueous solution of a light-sensitive diazo compound.
• the method of preparing a presensitized aluminum base planographic printingiplate comprising treating at least one surface of a sheet of degreased. aluminum with an aqueous solution of phosphon'eacidof a concentration in the range of .01 percent to 5 percent for between one second and three minutes at a temperature between 50 F. and F., and then rendering said acid-treated surface hydrophilic by a subsequent treatment with an aqueous solution of K ZrF of a concentration between .01 percent to saturated, ,at a temperature between 90 F. to F. for one to three minutes, soaking said sheet in hot water of a temperature between 100 F. and F. for one to five minutes, and hardening the surface coating thereon by treatment with an aqueous solution of citric acid and then applying to said plate an aqueous solution of a light-sensitive diazo compound, 7

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• Chemical & Material Sciences (AREA)
• Organic Chemistry (AREA)
• Printing Plates And Materials Therefor (AREA)

Priority Applications (6)

Applications Claiming Priority (1)

Publications (1)

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Family Applications (1)

Country Status (6)

Cited By (28)

Citations (3)

Family Cites Families (1)

• 0
  • DE DEP24130A patent/DE1183919B/de active Pending
  • NL NL254170D patent/NL254170A/xx unknown
  • BE BE593341D patent/BE593341A/xx unknown
• 1958
  • 1958-12-29 US US783155A patent/US2946683A/en not_active Expired - Lifetime
• 1959
  • 1959-11-19 GB GB39297/59A patent/GB884110A/en not_active Expired
  • 1959-12-11 FR FR812784A patent/FR1269595A/fr not_active Expired

Patent Citations (3)

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