Core/shell polymer particles as surface sizing agents

• US 10,640,926 B2
• Filed: 09/02/2016
• Issued: 05/05/2020
• Est. Priority Date: 09/04/2015
• Status: Active Grant

• Current Assignee: Kemira Oyj
• Original Assignee: Kemira Oyj
• Inventors: Lepo, Anneli, Turunen, Elsi, Turkki, Tarja, Uberbacher, Bernhard
• Primary Examiner(s): Cordray, Dennis R
• Application Number:
  US15/756,900
• Publication Number:
  US 20180251945A1
• Time in Patent Office: Days
• Field of Search: None
• CPC Class Codes: C08F 212/08 Styrene
• CPC Class Codes: C08F 220/18 with acrylic or methacrylic acids
• CPC Class Codes: C08F 220/1804 C4-(meth)acrylate, e.g. butyl (meth)acrylate, isobutyl (meth)acrylate or tert-butyl (meth)acrylate
• CPC Class Codes: C08F 220/44 Acrylonitrile
• CPC Class Codes: C08F 251/00 Macromolecular compounds obtained by polymerising monomers on to polysaccharides or derivatives thereof
• CPC Class Codes: C08F 265/06 Polymerisation of acrylate or methacrylate esters on to polymers thereof
• CPC Class Codes: C08F 285/00 Macromolecular compounds obtained by polymerising monomers on to preformed graft polymers
• CPC Class Codes: C08L 1/02 Cellulose; Modified cellulose
• CPC Class Codes: C08L 2207/53 Core-shell polymer
• CPC Class Codes: C08L 3/02 Starch; Degradation products thereof, e.g. dextrin
• CPC Class Codes: C09D 133/08 Homopolymers or copolymers of acrylic acid esters
• CPC Class Codes: D21H 17/20 Macromolecular organic compounds
• CPC Class Codes: D21H 19/22 Polyalkenes, e.g. polystyrene
• CPC Class Codes: D21H 21/16 Sizing or water-repelling agents
• CPC Class Codes: D21H 21/54 being spherical, e.g. microcapsules, beads
• CPC Class Codes: D21H 23/22 Addition to the formed paper

Abstract

The present invention provides a core/shell polymer particle for surface sizing of cellulosic products, wherein the core polymer and the shell polymer of the core/shell polymer particle are polymerized from monomers comprising at least 40%, by weight of monomers selected from branched C3-10-alkyl (meth)acrylate, styrene, linear C1-10-alkyl (meth)acrylate, and acrylonitrile, based on the total weight of the monomers of the core/shell polymer particle; provided that the polymer of the core/shell polymer particle comprises at least 40% by weight of branched C3-6-alkyl (meth)acrylate and at least 50% by combined weight of branched C3-10-alkyl (meth)acrylate and styrene, linear C1-10-alkyl (meth)acrylate, and/or acrylonitrile, based on the total weight of the monomers of the core/shell polymer particle.

Claims

1. A core/shell polymer particle for surface sizing of cellulosic products,

wherein the core polymer and the shell polymer of the core/shell polymer particle are polymerized from monomers comprising one or more selected from tert-butyl acrylate, n-butyl acrylate, and acrylonitrile;

provided that the polymer of the core/shell polymer particle comprises at least 40% by weight of tert-butyl acrylate and at least 50% by combined weight of at least one of tert-butyl acrylate, n-butyl acrylate, and acrylonitrile, based on the total weight of the monomers of the core/shell polymer particle;

wherein the core/shell polymer comprises;

(a) a core polymer polymerized from monomers comprising at least 25% by weight, of monomers selected from tert-butyl acrylate, n-butyl acrylate, and acrylonitrile; and

(b) a shell polymer polymerized from monomers comprising at least 25% by weight, of tert-butyl acrylate, based on total weight of the monomers of the core/shell polymer particle, and wherein the shell polymer encapsulates the core polymer; and

wherein 10 to 60 wt % of the core/shell polymer particle is degraded starch with a molecular weight M_n of 500 to 10,000.

2. The core/shell polymer particle as claimed in claim 1, wherein the core/shell polymer comprises at least 50% by weight branched C_3-10-alkyl (meth)acrylate and at least 75% by total weight, of branched C_3-6-alkyl acrylate and acrylonitrile, based on the total weight of the monomers of the core/shell polymer particle.

3. The core/shell polymer particle as claimed claim 1, wherein the core/shell polymer comprises at least 60% by weight, of branched C_3-10-alkyl (meth)acrylate based on the total weight of the monomers of the core/shell polymer particle.

4. The core/shell polymer particle as claimed in claim 1, wherein the shell polymer comprises at least 50% by weight of branched C_3-10-alkyl (meth)acrylate, based on the total weight of the shell polymer monomers.

5. The core/shell polymer particle as claimed in claim 1, wherein the core polymer comprises 50 to 100% by weight of monomers selected from branched C_3-10-alkyl (meth)acrylate, styrene, linear C_1-10-alkyl (meth)acrylate, and acrylonitrile, and any mixtures thereof, based on the total weight of the core polymer monomers.

6. The core/shell polymer particle as claimed in claim 5, wherein the branched C_3-10-alkyl (meth)acrylate is tert-butyl acrylate.

7. The core/shell polymer particle as claimed in claim 5, wherein the linear C_1-10-alkyl (meth)acrylate is n-butyl acrylate.

8. The core/shell polymer particle as claimed in claim 1, wherein the ratio of the weight of the core polymer monomers to the weight of the shell polymer monomers is preferably from 75:

25 to 25;

75.

9. The core/shell polymer particle as claimed in claim 1, wherein the shell polymer has a glass transition temperature from 35 to 75°

C.

10. The core/shell polymer particle as claimed in claim 1, wherein the core polymer has a glass transition temperature below 75°

C.

11. The core/shell polymer as claimed in claim 1, wherein the particle size distribution D50 of the core/shell polymer particle is below 110 nm.

12. The core/shell polymer as claimed in claim 1, wherein the core polymer and the shell polymer of the core/shell polymer particle are polymerized from monomers in presence of degraded starch or water-soluble natural or synthetic polymer.

13. A surface sizing composition comprising core-shell polymer as defined in claim 1.

14. The surface sizing composition as claimed in claim 13, wherein the starch is anionic starch.

15. A method of surface sizing a cellulosic product, comprising applying to at least one surface of the cellulosic product a sizing composition comprising core-shell polymer particles as defined in claim 14.

16. A surface-sized cellulosic product comprising the surface sizing composition as defined in claim 13.

17. A method of surface sizing a cellulosic product, comprising applying to at least one surface of the cellulosic product a surface sizing composition as defined in claim 13.

18. The method as claimed in claim 17, wherein the cellulosic product is paper.

19. A surface-sized cellulosic product comprising the core-shell polymer particles as defined in claim 1.

20. A method of surface sizing a cellulosic product, comprising applying to at least one surface of the cellulosic product a core-shell polymer as defined in claim 1.

21. The core/shell polymer particle as claimed in claim 1, wherein at least 80 wt % of the monomers are one or more monomers selected from the group consisting of tert-butyl (meth)acrylate, n-butyl (meth)acrylate, styrene and acrylonitrile.