Surface treatment of substrate or paper/paperboard products using optical brightening agent

• US 7,622,022 B2
• Filed: 06/01/2006
• Issued: 11/24/2009
• Est. Priority Date: 06/01/2006
• Status: Active Grant

• Current Assignee: International Paper Company
• Original Assignee: International Paper Company
• Inventors: Skaggs, Benny J, Bovee, Matt
• Primary Examiner(s): Halpern; Mark
• Application Number:
  US11/445,422
• Publication Number:
  US 20070277950A1
• Time in Patent Office: 1,272 Days
• Field of Search: 252/301.21, 252/301.22, 252/301.23, 510/394, 544/193.2, 864/8
• US Class Current: 162/162
• CPC Class Codes: B32B 9/06 of paper or cardboard
• CPC Class Codes: D21H 19/12 applied as a solution using water as the only solvent, e.g. in the presence of acid or alkaline compounds
• CPC Class Codes: D21H 19/824 two superposed coatings, both being non-pigmented
• CPC Class Codes: D21H 21/30 Luminescent or fluorescent substances, e.g. for optical bleaching D21H21/40 takes precedence
• CPC Class Codes: D21H 23/50 Spraying or projecting D21H23/44, D21H23/66 take precedence
• CPC Class Codes: Y10T 428/31975 Of cellulosic next to another carbohydrate
• CPC Class Codes: Y10T 428/31982 Wood or paper
• CPC Class Codes: Y10T 428/31993 Of paper

Abstract

The present invention relates to a process for applying optical brightening agent (OBA) to a sheet of paper or paperboard substrate. The process comprises the step of spraying an aqueous composition comprising an optical brightening agent onto at least one surface of a sized paperboard substrate to form a treated paperboard substrate. The treated paperboard substrate includes a layer of OBA on at least one surface of the paper or paperboard substrate in which the brightness of the treated paper or paperboard substrate is greater than the sized paper or paperboard substrate before treating thereof.

Claims

1. A process for applying optical brightening agent to a surface sized paper or paperboard substrate, the process comprising:

spraying an aqueous composition comprising an optical brightening agent (OBA) onto at least one surface of the sized paper or paperboard substrate having a surface TAPPI brightness of (x) to form a treated sized paper or paperboard substrate having a layer of OBA on the at least one surface of the sized paper or paperboard substrate having a surface TAPPI brightness of (y), wherein (y) is greater than (x) and wherein the spraying of the aqueous composition conducted right after the size press and prior to dryer devices within a papermaking machine process.

2. The process of claim 1 wherein the treated paper or paperboard substrate comprises of a layer of base stock, a layer of starch sizing on a surface of the base stock, and the layer of OBA.

3. The process of claim 1 wherein the aqueous composition comprises less than about 2 wt % of OBA based on the total weight of the aqueous composition.

4. The process of claim 1 wherein the optical brightening agent on the surface of the treated sized paper or substrate being in amount from about 0.1 wt % to about 2 wt % per ton of total weight of paper or paperboard substrate.

5. The process of claim 1 wherein the aqueous composition is sprayed using a plurality of spray nozzles arrayed to extend across a width of the sized paper or paperboard substrate.

6. The process of claim 5 wherein a distance between the spraying nozzle and the paper or paperboard substrate is from 10 mm to 200 mm.

7. The process of claim 1 wherein the aqueous composition is atomized.

8. The process of claim 7 wherein the aqueous composition is atomized by mixing with a stream of air under pressure before being applied onto the surface of the paper or paperboard substrate.

9. The process of claim 8 wherein the pressure of air ranges from about 10 psi to about 60 psi process.

10. The process of claim 1 wherein the aqueous composition supplied to the spraying nozzles at pressure from about 10 psi to about 60 psi.

11. The process of claim 1 wherein the paperboard substrate is lightweight base stock in range of about 10 lbs/3300 ft2 to about 300 lbs/3300 ft².

12. The process of claim 1 wherein the spraying comprises steps of introducing the aqueous composition into a mixing chamber having multiple spray nozzles thereon and wherein the mixing chamber configured to be extending across a width of the moving paper or paperboard substrate;

and dispersing the aqueous composition from the mixing chamber onto the one surface of the moving paper or paperboard substrate wherein the mixing chamber is positioned proximate the one surface of the moving paper or paperboard substrate.

13. The process of claim 1 wherein the OBA is applied to the paperboard substrate before the reel operation.

14. The process of claim 1 wherein the OBA is applied to the moving sized paperboard substrate in amount of from about 10 lbs to about 20 lbs of OBA per ton of paperboard.

15. The process of claim 1 wherein forming the treated surface of the paperboard substrate reduces the usage of OBA by at least 30% while maintaining or improving optical properties of the web of the paper.