Method for controlling the deposition of stickies in pulping and papermaking processes

1. A method for controlling the deposition of stickies in pulping and papermaking processes which comprises adding to fibre pulp or stock an additive comprising an organo-modified siloxane comprising units of the formula:

[R 1 a Z b SiO (4-a-b)/2 ] n

in which each R 1 is independently selected from a hydrogen atom, an alkyl, aryl, alkenyl, aralkyl, alkaryl, alkoxy, alkanoyloxy, hydroxyl, ester or ether group;

each Z is independently selected from an alkyl group substituted with an amine, amide, carboxyl, ester, or epoxy group, or a group —R 2 —(OC p H 2p ) q (OC r H 2r ) s —R 3 ;

n is an integer greater than 1;

a and b are independently 0, 1, 2 or 3;

R 2 is a direct bond, methylene, ethylene, propylene, butylene, pentylene or hexylene group;

R 3 is a hydrogen atom, alkyl, hydroxyl, alkoxy, ester or ether group;

p and r are independently 2, 3 or 4;

one of q and s is 0 or q+s is an integer such that 1≤q+s≤400;

wherein each molecule of the organo-modified siloxane contains at least one or more Z groups —R 2 —(OC p H 2p ) q (OC r H 2r ) s —R 3 ; and

wherein the additive is added in a stock preparation unit, a pulper outlet, to the fibre pulp or stock, or combinations thereof, either before, during or after fibre disintegration of either virgin or recycled cellulosic material.

2. The method according to claim 1 , wherein q and s are each independently from 5 to 30.

3. The method according to claim 2 , wherein q and s are each independently from 10 to 25.

4. The method according to claim 1 , wherein at least one or more Z groups are an alkyl group substituted with an amine, amide, carboxyl, ester, or epoxy group, and/or wherein at least one or more Z groups are an alkyl group having from 1 to 6 carbon atoms selected from the group consisting of a substituted methyl, ethyl, propyl, butyl, pentyl and hexyl group.

5. The method according to claim 1 , wherein 2 to 20 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z.

6. The method according to claim 5 , wherein 5 to 18 mole percent of silicon atoms in the siloxane molecule are substituted by a group Z.

7. The method according to claim 1 , wherein the molecular weight of the siloxane is 1,000-500,000.

8. The method according to claim 1 , wherein the organo-modified siloxane is a hydroxyl- or alkyl-endcapped linear polydimethylsiloxane, in which 5 to 18 mole percent of silicon atoms are substituted by Z groups of the formula —R 2 —(OC p H 2p ) q (OC r H 2r ) s —R 3 , in which p is 2, r is 3 and q and s are independently 10 to 20.

9. The method according to claim 8 , wherein 11 mole percent of silicon atoms are substituted with said Z groups, q and s are both 18, and the organo-modified siloxane has a molecular weight of about 60,000.

10. The method according to claim 1 , wherein the additive comprises the organo-modified siloxane together with one or more components selected from a polydimethylsiloxane, an organic polyether or a fatty acid ester thereof, a fatty acid ester with C 1-4 mono or polyvalent alcohol or an unsaturated or saturated fatty acid of natural origin or a soap thereof.

11. The method according to claim 10 , wherein the one or more components comprises an organic polyether having the formula R 4 —(OC p H 2p ) q (OC r H 2r ) s —R 5 in which R 4 and R 5 are independently selected from a hydrogen atom, hydroxyl, alkyl, alkoxy or ester groups, p and r are independently an integer from 1 to 6, and q and s are independently 0 or an integer such that 1≤q+s≤400.

12. The method according to claim 1 , wherein the additive is in the form of a solution, micro-emulsion, emulsion, dispersion or any combination thereof, and/or comprises a water soluble and/or emulsifying siloxane.

13. The method according to claim 1 , wherein the additive is added in an amount of less than 0.01 weight % of fibre in the pulp as dry material.

14. The method according to claim 1 , wherein the stickies are detected and measured using flow cytometry.

15. The method according to claim 1 , wherein q and s are each independently from 15 to 20, and p is 2, and r is 3.