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GB2029592A - Storage stable lithographic printing plates - Google Patents

Storage stable lithographic printing plates Download PDF

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Publication number
GB2029592A
GB2029592A GB7927667A GB7927667A GB2029592A GB 2029592 A GB2029592 A GB 2029592A GB 7927667 A GB7927667 A GB 7927667A GB 7927667 A GB7927667 A GB 7927667A GB 2029592 A GB2029592 A GB 2029592A
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GB
United Kingdom
Prior art keywords
lithographic printing
printing plate
acid
coating
hydrogen
Prior art date
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Granted
Application number
GB7927667A
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GB2029592B (en
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Polychrome Corp
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Polychrome Corp
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Publication date
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Publication of GB2029592A publication Critical patent/GB2029592A/en
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Publication of GB2029592B publication Critical patent/GB2029592B/en
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Classifications

    • GPHYSICS
    • G03PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03FPHOTOMECHANICAL PRODUCTION OF TEXTURED OR PATTERNED SURFACES, e.g. FOR PRINTING, FOR PROCESSING OF SEMICONDUCTOR DEVICES; MATERIALS THEREFOR; ORIGINALS THEREFOR; APPARATUS SPECIALLY ADAPTED THEREFOR
    • G03F7/00Photomechanical, e.g. photolithographic, production of textured or patterned surfaces, e.g. printing surfaces; Materials therefor, e.g. comprising photoresists; Apparatus specially adapted therefor
    • G03F7/004Photosensitive materials
    • G03F7/016Diazonium salts or compounds
    • G03F7/021Macromolecular diazonium compounds; Macromolecular additives, e.g. binders

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  • Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • General Physics & Mathematics (AREA)
  • Photosensitive Polymer And Photoresist Processing (AREA)
  • Phenolic Resins Or Amino Resins (AREA)
  • Materials For Photolithography (AREA)
  • Printing Plates And Materials Therefor (AREA)

Abstract

Storage stable lithographic printing plates comprising a metal sheet substrate having coated thereon a composition comprising a light sensitive, high molecular weight diazo polymers having the generic formula: <IMAGE> Where R is methyl or hydrogen X is methoxy, ethoxy or hydrogen Y is oxygen or sulfur Z is an anion of a sulfonic, carboxylic or phosphonic acid n is an integer from 8 to 970

Description

SPECIFICATION Storage stable lithographic printing plates This invention relates to storage stable lithographic printing plates comprising a metal substrate having coated thereon a composition comprising certain lithographic photosensitizers which are optionally blended with a suitable dye and a compatible resin in an acceptable solvent system.
It has been a problem in the past to produce commercially satisfactory lithographic printing plates which retain their ability to be effectively exposed and developed many years after their original manufacture.
Planographic printing plates must be carefully prepared so as to maintain their ability to differentiate between hydrophilic and oleophilic areas on its surface.
The prior art has described a plethora of photosensitive compositions which may be employed to produce such plates. One such example is the condensation product of paradiazo diphenyl amine with paraformaldehyde which has subsequently been reacted with a sulfonic acid. Typically, the shelf life of materials which have been used in the past to form such plates is less than two years and usually from about 1 yearto 1-1/2 years.
The present invention provides a lithographic printing plate employing certain specific photosensitizers wherein the obtained shelf life is in excess of five years.
It is known in the part to produce diazo type photosensitizers. In particular, U.S. Patent 3,373,021 discloses diazo compounds which are relatively low molecular weight monomers, whereas the instant invention uses only high molecular weight polymers.
By a selection of particular diazo type polymeric photosensitizers the present invention provides storage stable lithographic printing plates whose shelf-life is substantially extended as compared to plates coated with other photosensitizers known to the prior art. The polymeric photosensitizers used in the present invention are represented by the formula:
Where R is methyl or hydrogen X is methoxy, ethoxy or hydrogen Y is oxygen or sulfur Z is an anion of a sulfonic, carboxylic or phosphonic acid n is an integer from 8 to 970 These photosensitizers are described and claimed in our copending patent application No. 1134/78.
Accordingly the present invention provides a lithographic printing plate which comprises a metal substrate having coated thereon a composition which comprises a light-sensitive high molecular weight diazo polymers having the general formula set forth above.
In the above general formula the anions usable within the context of the instant invention include anions which form a stable salt with the diazo resin and which render it soluble in organic solvents. These include the anions derived from organic carboxylic acids such as, decanoic acid and benzoic acid, organic phosphonic acids such as phenylphosphonic acid, and sulfonic acids, typical examples of which include aliphatic and aromatic sulfonic acids, such as methane sulfonic acid, chloroethanesulfonic acid, dodecanesulfonic acid, benzenesuifonic acid, toluenesulfonic acid, mesitylenesulfonic acid, and anthraquinonesulfonic acid. Preferred sulfonic acids are 2-hydroxy-4-methoxybensophenone-5-sulfonic acid, hydroquinonesulfonic acid, 4-acetyl-benzenesulfonic acid and dimethyl-5-sulfoisophthalate.
Generally in the production of the coating composition used in the present invention, a diazonium salt is treated with paraformaldehyde and sulfuric acid. The reaction product thus produced is then treated with a sulfonic, carboxylic or phosphonic acid to produce the desired condensation product. This light sensitive composition may optionally be blended with such oleophilic binding resins as, polyamides, polyesters, polyethers, polycarbonates, polystyrenes, polyurethanes, polyvinyl chloride and its copolymers, polyviny Iketals, polynitriles, polysulfones. The selection of particular ingredients and reaction conditions is made and controlled by the skilled worker to achieve a composition having the desired properties including molecular weight.
In a series of preferred embodiments, it has been found beneficicial to produce the said coating composition such that in the general formula set forth hereinabove, R is methyl, X is ethoxy, Y is sulfur, Z is 2-hydroxy-4-methoxy bensophenone-5 sulfonic acid and n is selected such that the molecular weight of the polymer is from about 60,000 to about 80,000.
The following specific examples illustrate the invention and methods of producing the polymers but it is to be understood that variations and modifications can be made therein without departing from the spirit and scope of the invention.
Example (i) 120 g of 2,5-diethoxy-4-tolymercaptodiazobenzene zinc chloride double salt was added slowly to 385 ml of 98% sulfuric acid at 25 C. and stirred for 15 minutes while hydrogen chloride evolved. 8.03 g of paraformaldehyde was added and the mixture was stirred for 4 hours at 32 + 2 C. The reaction product was poured into 2.9 liters of ice water with stirring and treated with a cold concentrated solution of 383 g of zinc chloride in water. The precipitate was recovered by suction filtration and the partially dry cake was dissolved in 3.8 liters of water, filtered, cooled with ice and treated with a solution of 96 g of 2-hydroxy-4-methoxy benzophenone-5-sulfonic acid in water. The precipitate was recovered by filtration and air dried to obtain 175 g of brittle solid.
(ii) The light sensitive diazo resin prepared in (i) above was incorporated in a light sensitive coating solution by the following method.
To 80 ml. methylene chloride, 56 ml. methanol, 35 ml. methyl cellosolve (Registered Trade Mark) and 3.5 mi. of dimethylformamide was added 2.0 g. of the above light-sensitive diazo resin, 1.0 g. of Epon 1031 resin, 0.5 g. of Formvar (Registered Trade Mark)12/85 resin, 1.6 g. of a 60% solution of a polyester resin, 0.2 g. Basic blue due, 0.02 g. of 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid available from GAF under the name MS-40, 0.03 g. methyl orange and 4 ml. of a phosphoric acid solution prepared by diluting 1 g. of concentrated phosphoric acid in 100 ml. of methyl cellosolve.
The materials were added to the solvent mixture while the mixture was stirred. Each material readily dissolved.
The photosensitive solution was whirl-coated onto a grained anodized aluminum plate having a sodium silicate interlayer at a speed 80 rpm. During whirl-coating the aluminum plate was heated with electrical heating units. The temperature of the aluminum was approximately 70 to 80 degrees C. Within one minute the plate was dry and was kept in the whirl-coater and heated for a total of 5 minutes. This coating is identified as coating A.
Coating B was prepared by the same procedure as Coating A except that only 1 g. of the light sensitive diazo resin was used.
Coating C was prepared by the same procedure as Coating A except that a different diazo sensitizer was used. That sensitizer is the commonly used diazo resin for lithographic plates and is made by the condensation of p-diazodiphenylaminebisulfate with p-formaldehyde. The water soluble resin is then further reacted with MS-40 to form a sulfonate.
All three coatings as soon as they were prepared were imaged through a negative in a Berkey Exposure Unit by a method well known in the art. After light exposure they were developed with a developer. The plates are negative-working and the non-exposed areas were removed. The three coatings all produced satisfactory images and were totally developed. The non-image areas were all hydrophilic. No coating remained on the aluminum in the non-light exposed areas.
The developer used in this test was made according to the following formula.
Water 998 ml.
Lithium benzoate 963 ml.
Cyna-SO (Surfactant available from Mona Industries) 860 ml.
Sodium Lauryl Sulfate 247 g.
Sodium Citrate 247 g.
n-Propanol 482 ml.
Benzyl Alcohol 136 ml.
In developing the exposed coating a sufficient amount of developer is used to cover the entire plate. The developer is kept in contact with the plate for 30 seconds before the developer is rubbed into the plate gently by the use of a cotton swab or pad. The developer is then removed from the plate by the use of squeegee. A second application of developer is applied to the plate and the process is repeated.
After the development process, it is usually apparent if part of the coating remains in the unexposed areas.
If any part of the coating remains, it would be colored. As a further test, in determining if the unexposed areas are totally removed the process of printing on a printing press is simulated. The plate is first treated with water and the excess water is removed by a squeegee. The wet plate is then rubbed gently with a cotton swab that contains a blotch of a typical lithographic ink. The image will accept the ink while the non-image areas will not accept ink. All three coatings did not accept ink in the non-light exposed areas. The coatings in these areas are therefore totally removed.
One problem in the preparation of lithographic plates is that the light sensitive coatings are not sufficiently stable and when stored for an extended period of time at room temperature will undergo chemical changes.
These changes manifest themselves by changing the solubility characteristics of the coating in the developer which is obviously undesirable and cause the coatings to be unuseable.
To predict the long term stability properties of the 3 coatings, they were heated in an oven at 60 degrees C.
for periods ranging from 5 days to 3 weeks. The coatings were then exposed and developed as previously described. The results are summarized in the table below.
DAYS OF OVEN AGING AT 60 DEGREES C.
5Days 7Days 14 Days 21 Days Coating A Stable Stable Stable Stable Coating B Stable Stable Stable Stable Coating C Stable Unstable Unstable Unstable A simulated oven aging of one day at 60 degrees C translates to a 3 month shelf life. It can readily be seen that Coating C, which is known in the art, is stable for an estimated 1-1/4 year shelf life and unstable by 1-3/4 years. However, the sensitizer of the present invention has been shown to be stable for over 5-1/4 years.
As a series of preferred embodiments, a composition produced according to the present invention is applied at a coating weight of from about 10 mg/sq. ft. to about 200 mg/sq. ft. on an aluminum sheet and dried. The thus formed coated film may then be exposed to ultraviolet radiation through a transparency in a manner well known to the art and developed using a suitable developer such as Polychrome's 922 developer.

Claims (8)

1. A lithographic printing plate which comprises a metal sheet substrate having coated thereon a composition which is comprised of a light sensitive, high molecular weight diazo polymer having the formula:
Where R is methyl or hydrogen X is methoxy, ethoxy or hydrogen Y is oxygen or sulfur Z is an anion of a sulfonic, carboxylic or phosphonic acid n is an integer from 8 to 970
2. A lithographic printing plate as claimed in claim 1 wherein said coated composition further comprises an oleophilic binding resin.
3. A lithographic printing plate as claimed in claim 2 wherein the binding resin is a substance selected form the group consisting of polyamides, polyesters, polyethers, polycarbonates, polystyrenes, polyurethanes, polyvinyl chloride and its copolymers, polyvinylketals, polynitriles, polysulfones.
4. A lithographic printing plate as claimed in any of claims 1 to 3 wherein said metal sheet substrate is comprised of aluminium or the alloys of aluminium.
5. A lithographic printing plate as claimed in any of claims 1 to 4 wherein R is methyl, X is ethoxy, Y is sulfur and Z is an anion of a sulfonic acid.
6. A lithographic printing plate as claimed in claim 5 wherein said sulfonic acid is 2-hydroxy-4methoxybenzophenone-5-sulfonic acid.
7. A lithographic printing plate as claimed in claim 6 wherein the molecular weight of the polymer is in the range of from about 60,000 to about 80,000.
8. A lithographic printing plate as claimed in claim 1 substantially as hereinbefore described in the Example.
GB7927667A 1978-08-10 1979-08-08 Storage stable lithographic printing plates Expired GB2029592B (en)

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
US93274078A 1978-08-10 1978-08-10

Publications (2)

Publication Number Publication Date
GB2029592A true GB2029592A (en) 1980-03-19
GB2029592B GB2029592B (en) 1982-10-20

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JP (1) JPS5525093A (en)
DE (1) DE2932377A1 (en)
GB (1) GB2029592B (en)

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135616A3 (en) * 1983-08-02 1987-01-28 American Hoechst Corporation Mixed photosensitive condensate and photosensitive registration material prepared therefrom
EP0194587A3 (en) * 1985-03-15 1988-01-13 Hoechst Aktiengesellschaft Light-sensitive diazonium salt polycondensation product, and light-sensitive registration material prepared therewith

Families Citing this family (5)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JPS5938746A (en) * 1982-08-27 1984-03-02 Okamoto Kagaku Kogyo Kk Photosensitive lithographic plate
JPS5938747A (en) * 1982-08-27 1984-03-02 Okamoto Kagaku Kogyo Kk Photosensitive lithographic plate
JPS5978340A (en) * 1982-10-28 1984-05-07 Fuji Photo Film Co Ltd Photosensitive composition
JP2571354B2 (en) * 1983-06-01 1997-01-16 富士写真フイルム株式会社 Photosensitive composition
US4785062A (en) * 1984-07-31 1988-11-15 W. R. Grace & Co.-Conn. Reaction product of O-epoxyalkylated tetrakis(hydroxyphenyl)ethane resin and phenol with product having no remaining epoxy groups

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB712606A (en) * 1949-05-05 1954-07-28 Kalle & Co Ag Improvements in or relating to photolithographic diazotype printing materials and processes
GB728205A (en) * 1953-05-22 1955-04-13 Warren S D Co Photo-sensitive diazotype coated paper plate for photo-lithography
GB880051A (en) * 1958-12-10 1961-10-18 Gen Aniline & Film Corp Negative working offset photomechanical plates
GB1129407A (en) * 1966-04-29 1968-10-02 Oce Van Der Grinten Nv Light-sensitive material for the production of printing plates

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB712606A (en) * 1949-05-05 1954-07-28 Kalle & Co Ag Improvements in or relating to photolithographic diazotype printing materials and processes
GB728205A (en) * 1953-05-22 1955-04-13 Warren S D Co Photo-sensitive diazotype coated paper plate for photo-lithography
GB880051A (en) * 1958-12-10 1961-10-18 Gen Aniline & Film Corp Negative working offset photomechanical plates
GB1129407A (en) * 1966-04-29 1968-10-02 Oce Van Der Grinten Nv Light-sensitive material for the production of printing plates

Cited By (2)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0135616A3 (en) * 1983-08-02 1987-01-28 American Hoechst Corporation Mixed photosensitive condensate and photosensitive registration material prepared therefrom
EP0194587A3 (en) * 1985-03-15 1988-01-13 Hoechst Aktiengesellschaft Light-sensitive diazonium salt polycondensation product, and light-sensitive registration material prepared therewith

Also Published As

Publication number Publication date
DE2932377A1 (en) 1980-02-28
JPS5525093A (en) 1980-02-22
GB2029592B (en) 1982-10-20

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