Claims
- 1. A gumming process for a lithographic printing plate, comprising applying a desensitizing gum to an exposed and developed presensitized lithographic printing plate, spreading the desensitizing gum all over the plate surface, wiping off excess desensitizing gum and drying, the desensitizing gum comprising water having dissolved therein 5 to 35 wt %, based on the total weight of the desensitizing gum, of at least one of a film-forming, water-soluble compound selected from the group consisting of (A) enzyme-decomposed dextrin prepared by decomposing a starch selected from the group consisting of potato starch, sweet potato starch, wheat starch, corn starch, tapioca starch and rice starch using an enzyme selected from the group consisting of .alpha.-amylase, .beta. amylase and saccharogenic amylase and (B) enzyme-decomposed etherified dextrin prepared by decomposing hydroxyethyl starch, hydroxypropyl starch and ethyl starch using an enzyme selected from the group consisting of .alpha.-amylase, .beta.-amylase and saccharogenic amylase; wherein said enzyme-decomposed dextrin or said enzyme-decomposed etherified dextrin is prepared by decomposition to the degree that said enzyme-decomposed dextrin or said enzyme-decomposed etherified dextrin contains 10 to 40 wt % of reducing sugar.
- 2. A gumming process as claimed in claim 1, wherein the film-forming, water-soluble compound is present in an amount in the range of 10 to 25 wt. %.
- 3. A gumming process as claimed in claim 1, wherein the desensitizing gum has a pH in the range of 3 to 6.
- 4. A gumming process as claimed in claim 1, wherein the desensitizing gum further comprises a pH adjusting agent selected from the group consisting of mineral acids, organic acids and inorganic acids, the pH adjusting agent present in an amount in the range of 0.01 to 2 wt. % based on the total weight of the desensitizing gum.
- 5. A gumming process as claimed in claim 1, wherein the desensitizing gum further comprises a surfactant.
- 6. A gumming process as claimed in claim 5, wherein the surfactant is present in an amount in the range of 0.01 to 10 wt. % based on the total weight of the desensitizing gum.
- 7. A gumming process as claimed in claim 1, wherein said desensitizing gum further comprises a wetting agent present in an amount in the range of 0.1 to 5.0 wt. % based on the total weight of the desensitizing gum.
- 8. A gumming process as claimed in claim 7, wherein the wetting agent is present in an amount in the range of 0.5 to 3.0 wt. % based on the total weight of the desensitizing gum.
- 9. A gumming process as claimed in claim 1, wherein the desensitizing gum further comprises an antiseptic present in an amount in the range of 0.005 to 2.0 wt. % based on the total weight of the desensitizing gum.
Priority Claims (1)
Number |
Date |
Country |
Kind |
57-159284 |
Sep 1982 |
JPX |
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Parent Case Info
This is ia continuation of application Ser. No. 531,796 filed Sept. 13, 1983, abandoned.
US Referenced Citations (6)
Non-Patent Literature Citations (2)
Entry |
Davidson et al, Water-Soluble Resins, Van Nostrand Reinhold (1962), New York. |
Strauss, The Lithographer's Manual, Waltwin Publishing Co. (1958), New York. |
Continuations (1)
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Number |
Date |
Country |
Parent |
531796 |
Sep 1983 |
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