Process for the deinking of coated paper or paperboard

Patent metadata

Field	Value
Publication number	US-10544544-B2
Application number	US-201615760500-A
Country	US
Kind code	B2
Filing date	Oct 10, 2016
Priority date	Oct 12, 2015
Publication date	Jan 28, 2020
Grant date	Jan 28, 2020

Abstract

A process for the deinking of a coated paper or paperboard is disclosed, the process comprises a step of providing a coating layer comprising a calcium- or magnesium-exchanged clay which is deposited on the paper or paperboard before the ink layer. In a further step said calcium- or magnesium-exchanged clay is activated and the paper is subsequently treated with water.

First claim

The invention claimed is:

1. A process for the deinking of coated paper or paperboard, comprising the following steps:
(i) providing a coated paper or paperboard comprising,
(a) at least one layer consisting of a coating composition comprising,
(a1) a calcium- or magnesium-exchanged clay, and
(a2) a binder, wherein the content of the binder in the coating composition is in the range from 0.1 to 12 wt %, based on the total solids weight of the coating composition;

(b) at least one layer having a thickness in the range from 0.1 to 10 μm comprising ink, wherein layer (a) is deposited on the paper or paperboard before layer (b);

(ii) activating the calcium- or magnesium-exchanged clay of the coating composition layer during step (iii) by,
providing in step (i) the binder, wherein the binder is soluble in water and comprises monovalent ions selected from the group consisting of sodium, lithium, potassium, ammonium and mixtures thereof, and

(iii) treating the coated paper or paperboard as provided in step (i) with water to obtain an aqueous suspension comprising at least ink, clay particles and a paper pulp or a paper residue.

2. The process according to claim 1 , wherein the process comprises a further step (iv) of separating the paper pulp or a paper residue from the aqueous suspension obtained in step (iii).

3. The process according to claim 1 , wherein the clay is a calcium-exchanged nanoclay selected from the group consisting of bentonite, smectite, montmorillonite and mixtures thereof and preferably is bentonite.

4. The process according to claim 1 , wherein the activating step (ii) further comprises,
carrying out step (iii) with water comprising monovalent ions selected from the group consisting of sodium, lithium, potassium, ammonium and mixtures thereof; and/ or
adding sodium ions in the form of a salt selected from the group consisting of sodium chloride, sodium nitrate, sodium sulphate, sodium carbonate and mixtures-thereof before or during step (iii), and after step (i).

5. The process according to claim 1 , wherein the binder is water soluble carboxymethylcellulose and comprises an excess of sodium ions with respect to the calcium or magnesium ions of the calcium- or magnesium-exchanged clay.

6. The process according to claim 1 , wherein the coated paper comprises at least one layer (c) comprising 1 to 30 g/m 2 of a calcium carbonate-comprising material, wherein layer (c) is arranged between layer (a) and layer (b).

7. The process according to claim 6 , wherein the calcium carbonate-comprising material is selected from ground calcium carbonate, precipitated calcium carbonate, surface-modified calcium carbonate, or a mixture thereof.

8. The process according to claim 6 , wherein the calcium carbonate-comprising material is from a natural calcium carbonate source, said natural calcium carbonate source selected from the group consisting of marble, limestone, chalk, dolomite, and mixtures thereof.

9. The process according to claim 1 , wherein the thickness of the at least one ink layer is in the range from 0.75 to 5 μm.

10. The process according to claim 1 , wherein the water applied in step (iii) is selected from the group consisting of tap water, tap water comprising sodium ions, deionized water and mixtures thereof.

11. The process according to claim 1 , wherein the content of the calcium- or magnesium-exchanged clay in the coating composition is in the range from 3 to 15 wt-%, based on the total weight of the coating composition, and/or the coating weight of the at least one layer (a) is from 0.1 to 20 g/m 2 .

12. The process according to claim 1 , wherein the content of the binder in the coating composition is in the range from 0.2 to 5 wt.-% based on the total solids weight of the coating composition.

13. The process according to claim 1 , wherein the ink in layer (b) is a digital printing ink selected from the group consisting of ink- or dye-based inkjet inks, laser printing inks and/or toners, offset inks, flexographic inks, rotogravure inks and mixtures thereof.

14. The process according to claim 2 , wherein the process further comprises the steps of
(v) transferring the aqueous suspensions as obtained in step (iii) or (iv) to a flotation cell, and/or
(vi) adding at least one collector agent to the aqueous suspensions as obtained in step (iii), (iv) or (v), and
(vii) passing a flotation gas into the aqueous suspension formed in step (vi) to obtain a phase comprising water and a froth comprising clay and ink, and
(viii) separating the froth as obtained in step (vii) from the water.

15. The process according to claim 14 , wherein the at least one collector agent is selected from the group consisting of modified poylethyleneimines, active and hydrophobic tensides, alkyl sulphates, polyalkylenimines, primary amines, tertiary amines, quaternary amines, fatty amines, esterquats, polyesterquats, imidazolines, and quaternary imidazolium compounds.

16. The process according to claim 14 , wherein the content of the at least one collector agent is in the range from 0.001 to 50 wt.-% based on the total weight of the solids in the aqueous suspension as provided in step (iii) or (iv).

17. A process for the deinking of coated paper or paperboard, comprising the following steps:
providing a coated paper or paperboard comprising,
(a) at least one layer consisting of a coating composition comprising,
(a1) a calcium- or magnesium-exchanged clay,
(a2) a binder,

(b) at least one layer having a thickness in the range from 0.1 to 10 μm comprising ink,
wherein layer (a) is deposited on the paper or paperboard before layer (b); and

(ii) activating the calcium- or magnesium-exchanged clay by,
(A) carrying out step (iii) with water comprising monovalent ions selected from the group consisting of sodium, lithium, potassium, ammonium and mixtures thereof, and/or
(B) providing the binder in step (i), wherein the binder is soluble in water and comprises monovalent ions selected from the group consisting of sodium, lithium, potassium, ammonium and mixtures thereof, and/or
(C) adding monovalent ions selected from the group consisting of sodium, lithium, potassium, ammonium and mixtures thereof in form of a salt, wherein the salt is introduced before or during step (iii), and after step (i); and

(iii) treating the coated paper or paperboard provided in step (i) with water to obtain an aqueous suspension comprising at least ink, clay particles and a paper pulp or a paper residue, wherein mechanical scraping of the surface of the paper or paperboard is carried out during step (iii).

18. The process according to claim 17 , wherein the coated paper or paperboard comprises at least one layer (c) comprising a calcium carbonate-comprising material, wherein layer (c) is arranged between layer (a) and layer (b).

19. The process according to claim 17 , wherein the ink in layer (b) is a digital printing ink selected from the group consisting of ink- or dye-based inkjet inks, laser printing inks and/or toners, offset inks, flexographic inks, rotogravure inks and mixtures thereof.

20. The process according to claim 1 , wherein the binder is water soluble and comprising an excess of sodium ions with respect to the calcium or magnesium ions of the calcium- or magnesium-exchanged clay in the range from 10:1 to 100,000:1.

Assignees

• Omya Int Ag

Inventors

• Gane Patrick A C
• Rentsch Samuel
• Welker Matthias
• Ridgway Catherine Jean

Classifications

• D21H19/52

  Cellulose; Derivatives thereof · CPC title

• D21H19/40

  siliceous, e.g. clays · CPC title

• D21H19/54

  Starch · CPC title

• D21C5/027 Primary

  Chemicals therefor · CPC title

• D21C5/025

  De-inking · CPC title