FIBROUS WEB OF PAPER OR BOARD AND METHOD OF MAKING THE SAME

• US 20150114581A1
• Filed: 04/24/2013
• Published: 04/30/2015
• Est. Priority Date: 04/26/2012
• Status: Active Grant

• Current Assignee: Stora Enso Oyj
• Original Assignee: Stora Enso Oyj
• Inventors: Kinnunen, Karita, Hjelt, Tuomo
• Granted Patent: US 9,334,610 B2
• Time in Patent Office: Days
• US Class Current: 162/125
• CPC Class Codes: B32B 2250/26 All layers being made of paper or paperboard
• CPC Class Codes: B32B 29/005 next to another layer of paper or cardboard layer
• CPC Class Codes: B32B 5/26 another layer next to it also being fibrous or filamentary relative arrangement of fibres or filaments of different layers B32B5/12
• CPC Class Codes: B32B 7/02 Physical, chemical or physicochemical properties
• CPC Class Codes: D21F 11/002 by using a foamed suspension
• CPC Class Codes: D21H 11/18 Highly hydrated, swollen or fibrillatable fibres
• CPC Class Codes: D21H 17/09 Sulfur-containing compounds
• CPC Class Codes: D21H 21/24 Surfactants
• CPC Class Codes: D21H 21/56 Foam
• CPC Class Codes: D21H 27/30 Multi-ply for surface covering D21H27/18; making on paper-making machines D21F9/00, D21F11/00

Abstract

The invention relates to a fibrous web product such as paper, and a method for the preparation of such fibrous web. According to the method microfibrillated cellulose (MFC) together with a pulp of a greater fibre length, such as chemithermomechanical pulp (CTMP), are mixed with a foam of water and a sur-factant, the foam is supplied to a forming fabric of a paper or board machine, dewatered by suction of air through the forming fabric, and dried to the final web product. The method brings a high bulk in combination with a high Scott bond value, to provide improved wet and dry tensile strength for the paper and board products.

Claims

1. A method for the preparation of a fibrous web of paper or board, the method comprising the steps of:

providing a foam of water and a surfactant;

incorporating microfibrillated cellulose (MFC) together with a pulp of a greater fibre length in the foam;

supplying the foam onto a forming fabric;

dewatering the foam on the forming fabric by suction to form a web; and

subjecting the web to final drying.

2. The method of claim 1, wherein a continuous fibrous web is formed on a running forming fabric of a paper or board machine, dewatered by suction through the web and the forming fabric, and finally dried in a drying section of the paper or board machine.

3. The method of claim 1, wherein the web is dewatered by suction of air through the web and the forming fabric at a pressure of at most 0.6 bar, followed b predrying by suction of air at a pressure of at most about 0.3 bar.

4. The method of claim 1, wherein mechanical pulp is incorporated in the foam.

5. The method of claim 1, wherein the fibrous components incorporated in the foam consist of about 5 to 40 wt-% of MFC and about 60 to 95 wt-% of pulp with longer fibres.

6. The method of claim 1, wherein the foam is brought to an air content of 60 to 70 vol-% before being supplied onto the forming fabric.

7. The method of claim 1, wherein the surfactant is sodium dodecyl sulphate (SDS).

8. A fibrous web obtained by the method of claim 1, wherein the web comprises a mixture of microfibrillated cellulose (MFC) and a pulp of a greater fibre length, and that the web has a bulk of at least 2.5 cm³/g.

9. The fibrous web of claim 8, wherein the web has a bulk of 3 to 7 cm³/g.

10. The fibrous web of claim 8, wherein the web has a Scott bond value of at least 50 J/m².

11. The fibrous web of claim 8, wherein the pulp of a greater fibre length is mechanical pulp.

12. The fibrous web of claim 8, wherein the web comprises about 5 to 40 wt-% of MFC and about 60 to 95 wt-% of pulp of a greater fibre length.

13. A multilayer board, characterized in that at least one of the layers is a fibrous web according to claim 8.

14. The multilayer board of claim 13, characterized in that the board comprises as a middle layer a fibrous web according to claim 8, as well as outer layers having a bulk lower than in the middle layer.

15. The method of claim 4, wherein the mechanical pulp is chemithermomechanical pulp (CTMP).

16. The fibrous web of claim 10, wherein the Scott bond value is between 120 J/m² to 200 J/m².

17. The fibrous web of claim 11, wherein the pulp of a greater fibre length is CTMP.