# US 5,345,869 A · Lithographic plate, and method for making, having an oxide layer derived from a type A sol

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- Number: US 5,345,869 A
- Document ID: US5345869A
- Status: Granted
- Kind: A
- Application number: 07/917,045
- Filed: 1992-09-30
- Granted: 1994-09-13
- Earliest claimed: 1990-02-12
- Assignees: Alcan International Limited
- Inventors: John A. Treverton; Jonathan Ball
- Web page: https://patentgrep.com/patent/US5345869A

## CPC

- B41N 3/038: {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}
- Y10T 428/252: Glass or ceramic [i.e., fired or glazed clay, cement, etc.] [porcelain, quartz, etc.]
- B41N: PRINTING PLATES OR FOILS (photosensitive material G03); MATERIALS FOR SURFACES USED IN PRINTING MACHINES FOR PRINTING, INKING, DAMPING, OR THE LIKE; PREPARING SUCH SURFACES FOR USE AND CONSERVING THEM
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

A lithographic plate comprising a substrate carrying an oxide layer derived from a Type A sol is disclosed. The substrate may be metal, e.g. aluminum or steel, and may be in a mill finished state or grained or otherwise profiled. Type A sols have polynuclear cations but no specific particles and may be formed by peptising basic salts with acids. The sol may include an inorganic passenger powder which may impart a desired topography to the coating layer.

## Claims

### Claim 1

A lithographic plate comprising:
a substrate;
an oxide layer, said oxide layer directly overlying said substrate and being derived from a Type A sol which is itself derived from an inorganic precursor.

### Claim 2 (depends on 1)

A lithographic plate as claimed in claim 1, wherein the substrate is of aluminum metal.

### Claim 3 (depends on 2)

A lithographic plate as claimed in claim 2, wherein the substrate is an aluminum sheet which does not require any surface profiling.

### Claim 4 (depends on 1)

A lithographic plate as claimed claim 1, wherein the Type A sol is a hydrous metal oxide sol.

### Claim 5 (depends on 4)

A lithographic plate as claimed in claim 4, wherein the Type A sol is a zirconia sol.

### Claim 6 (depends on 1)

A lithographic plate as claimed in claim 1, wherein the oxide layer contains discrete inorganic particles below 10 .mu.m in diameter.

### Claim 7 (depends on 1)

A lithographic plate as claimed in claim 1, including also a photosensitive layer on the oxide layer.

### Claim 8 (depends on 1)

A lithographic plate as claimed in claim 1, wherein the substrate is of a metal selected from the group consisting of aluminum and steel.

### Claim 9 (depends on 8)

A lithographic plate as claimed in claim 8, wherein the substrate has a grained surface.

### Claim 10

A method of making a lithographic plate, which method comprises:
providing a substrate;
applying to the substrate a composition comprising a Type A sol derived from an inorganic precursor and;

### Claim 11 (depends on 10)

A method as claimed in claim 10, wherein the step of curing the composition applied to the substrate comprises:
heating the composition at a temperature of from 50.degree.-400.degree. C.

### Claim 12 (depends on 9)

A method as claimed in claim 9, wherein the Type A sol contains 1-300 g/l of inorganic particles below 10 .mu.m in diameter.

### Claim 13 (depends on 10)

A method as claimed in claim 10 wherein the Type A sol is a hydrous metal oxide sol.
curing the composition to form an oxide layer directly overlying the substrate.

### Claim 14 (depends on 11)

A method as claimed in claim 11, further comprising:
applying a photosensitive layer on the oxide layer.

### Claim 15 (depends on 8)

A method as claimed in claim 8, wherein the substrate is of a metal selected from the group consisting of aluminum and steel.

### Claim 16 (depends on 15)

A method as claimed in claim 15, wherein the substrate has a grained surface.