# US 4,400,440 A · Electrostatic paper base and method of making the same

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- Number: US 4,400,440 A
- Document ID: US4400440A
- Status: Granted
- Kind: A
- Application number: 06/222,014
- Filed: 1981-01-02
- Granted: 1983-08-23
- Earliest claimed: 1981-01-02
- Assignees: Allied Paper Incorporated
- Inventors: Michael J. Shaw
- Web page: https://patentgrep.com/patent/US4400440A

## CPC

- G03G 5/0205: {Macromolecular components}
- B41N 3/036: {characterised by the presence of a polymeric hydrophilic coating}
- D21H 19/56: Macromolecular organic compounds or oligomers thereof obtained by reactions only involving carbon-to-carbon unsaturated bonds
- D21H 25/02: Chemical or biochemical treatment (D21H25/18 takes precedence)
- Y10T 428/31895: Paper or wood
- G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY
- 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
- D21H: PULP COMPOSITIONS; PREPARATION THEREOF NOT COVERED BY SUBCLASSES D21C OR D21D; IMPREGNATING OR COATING OF PAPER; TREATMENT OF FINISHED PAPER NOT COVERED BY CLASS B31 OR SUBCLASS D21G; PAPER NOT OTHERWISE PROVIDED FOR
- Y10T: TECHNICAL SUBJECTS COVERED BY FORMER US CLASSIFICATION

## Abstract

There is provided a method of coating a paper substrate in either sheet or web form to form a base useful in forming electrostatic masters. A thin coating of a reactive film forming resin is applied to the paper and the resin reacted with an ammonium zirconyl complex and dried. This treatment avoids blocking or sticking together of successive layers of paper coated with relatively low glass transition temperature film forming resins.

## Claims

### Claim 1

A method for the preparation of a paper base suitable for electrostatic masters for lithographic printing comprising the steps of
(a) applying to at least one side of a paper substrate a thin coating of a barrier coating composition which comprises
(1) an aqueous medium,
(2) a film-forming amount of a synthetic, organic, polymeric, thermoplastic, water-resistant, film-forming resin which is solid at ordinary temperatures, and which has a glass transition temperature less than 115.degree. C., said film forming resin also having labile hydrogen-containing groups reactive with an ammonium zirconyl complex,
(3) less than 35% by weight (dry basis) of inorganic particulate material,
(4) the ratio of resin to inorganic particulate material being at least 2:1;
(b) cross-linking the resin in said coating with an ammonium zirconyl complex;
(c) passing said paper through a dryer operating at a temperature such that the temperature of said paper substrate and coating is elevated above said resin glass transition temperature; and
(d) positioning said coated paper following drying in successive layers;
(e) said coating composition being rendered non-blocking by cross-linking with the ammonium zirconyl complex whereby fusion of the successive layers is obviated.

### Claim 2 (depends on 1)

A method as defined in claim 1 wherein the coating composition is an aqueous colloidal dispersion of said resin.

### Claim 3 (depends on 1)

A method as defined in claim 1 wherein the paper is in the form of a paper web.

### Claim 4 (depends on 1)

A method as defined in claim 1 wherein the paper is in sheet form.

### Claim 5 (depends on 1)

A method as defined in claim 1 wherein said aqueous dispersion further includes from 10% to 30% by weight of the resin of a filler.

### Claim 6 (depends on 1)

A method as defined in claim 1 wherein said labile hydrogen groups are carboxyl.

### Claim 7 (depends on 1)

A method as defined in claim 1 wherein the labile hydrogen groups are carboxyl and the carboxyl containing moiety of the copolymer amounts to from 10% to 30% of the copolymer.

### Claim 8 (depends on 1)

A method as defined in claim 1 wherein the resin is an alkylene/unsaturated carboxylic acid copolymer.

### Claim 9 (depends on 8)

A method as defined in claim 8 wherein the alkylene/unsaturated carboxylic acid copolymer is an ethylene/acrylic acid copolymer.

### Claim 10 (depends on 9)

A method as defined in claim 9 wherein the ethylene moiety of the copolymer is from 80% to 90% by weight and the balance is acrylic acid.

### Claim 11 (depends on 1)

A method as defined in claim 1 wherein the ammonium zirconyl complex is ammonium zirconyl carbonate.

### Claim 12 (depends on 1)

A method as defined in claim 1 wherein the ammonium zirconyl complex is dissolved in the coating composition.

### Claim 13 (depends on 1)

A method as defined in claim 1 wherein an ammoniacal aqueous solution of an ammonium zirconyl complex is topically applied to the coated paper prior to drying.

### Claim 14 (depends on 1)

A method as defined in claim 1 wherein the ambient temperature in the drier is from 150.degree. to 160.degree. C.

### Claim 15 (depends on 4)

The method of claim 4 wherein the ratio of resin to inorganic particulate material is at least 5:1.

### Claim 16 (depends on 1)

A paper base prepared according to the method of claim 1.