POLYMER PARTICLES

• US 20140329932A1
• Filed: 05/31/2012
• Published: 11/06/2014
• Est. Priority Date: 05/31/2011
• Status: Active Grant

• Current Assignee: University of Sydney
• Original Assignee: University of Sydney
• Inventors: Hawkett, Brian Stanley, Nguyen, Duc Ngoc, Such, Christopher Henry, Baker, Matthew Paul, Davey, Timothy Warren
• Granted Patent: US 9,339,781 B2
• Time in Patent Office: Days
• US Class Current: 523/206
• CPC Class Codes: B01J 13/18 In situ polymerisation with all reactants being present in the same phase
• CPC Class Codes: B01J 13/22 Coating
• CPC Class Codes: C01P 2002/88 by thermal analysis data, e.g. TGA, DTA, DSC
• CPC Class Codes: C01P 2004/04 obtained by TEM, STEM, STM or AFM
• CPC Class Codes: C08F 2/18 Suspension polymerisation
• CPC Class Codes: C08F 2/22 Emulsion polymerisation
• CPC Class Codes: C08F 2/44 Polymerisation in the presence of compounding ingredients, e.g. plasticisers, dyestuffs, fillers
• CPC Class Codes: C08F 220/06 Acrylic acid; Methacrylic acid; Metal salts or ammonium salts thereof
• CPC Class Codes: C08F 220/14 Methyl esters , e.g. methyl (meth)acrylate
• 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 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: C08F 292/00 Macromolecular compounds obtained by polymerising monomers on to inorganic materials
• CPC Class Codes: C08K 2003/2241 Titanium dioxide
• CPC Class Codes: C08K 3/22 of metals
• CPC Class Codes: C08K 3/24 Acids; Salts thereof C08K3/16 takes precedence
• CPC Class Codes: C08K 9/10 Encapsulated ingredients
• CPC Class Codes: C09B 67/0013 with polymeric coatings
• CPC Class Codes: C09C 1/3676 Treatment with macro-molecular organic compounds
• CPC Class Codes: Y10T 428/2989 Microcapsule with solid core [includes liposome]

Abstract

The present invention relates to a method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising: providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising ethylenically unsaturated monomer and a stabiliser for the particulate material; and polymerising the ethylenically unsaturated monomer by non-living free radical polymerisation to form polymer that encapsulates the particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material; wherein polymerisation of the ethylenically unsaturated monomer comprises: (a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form a base responsive water swellable non-living polymer layer that encapsulates the particulate material; and (b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form an extensible, water and base permeable non-living polymer layer that encapsulates the base responsive water swellable polymer layer.

Claims

1. A method of preparing an aqueous dispersion of polymer encapsulated particulate material, the method comprising:

providing a dispersion of the particulate material in a continuous aqueous phase, the dispersion comprising ethylenically unsaturated monomer and a stabiliser for the particulate material; and

polymerising the ethylenically unsaturated monomer by non-living free radical polymerisation to form polymer that encapsulates the particulate material, thereby providing the aqueous dispersion of polymer encapsulated particulate material;

wherein polymerisation of the ethylenically unsaturated monomer comprises;

(a) polymerising a monomer composition that includes ionisable ethylenically unsaturated monomer so as to form a base responsive water swellable non-living polymer layer that encapsulates the particulate material; and

(b) polymerising a monomer composition that includes non-ionisable ethylenically unsaturated monomer so as to form an extensible, water and base permeable non-living polymer layer that encapsulates the base responsive water swellable polymer layer.

2. The method according to claim 1, wherein the monomer composition that is polymerised to form the water swellable non-living polymer layer comprises from about 10 wt % to about 40 wt % ionisable ethylenically unsaturated monomer.

3. The method according to claim 1, wherein the monomer composition that is polymerised to form the water swellable non-living polymer layer comprises methyl methacrylate (MMA), butyl acrylate (BA) and methacrylic acid (MA) and/or acrylic acid (AA).

4. The method according to claim 1, wherein the monomer composition that is polymerised to form the extensible, water and base permeable non-living polymer layer comprises greater than about 70 wt % of non-ionisable hydrophobic ethylenically unsaturated monomer.

5. The method according to claim 1, wherein the monomer composition that is polymerised to form the extensible, water and base permeable non-living polymer layer comprises styrene, methyl methacrylate and butyl acrylate.

6. The method according to claim 1 further comprising exposing the resulting polymer encapsulated particulate material to a basic aqueous environment such that the base responsive water swellable polymer layer swells and expands in volume, while at the same time the extensible, water and base permeable polymer layer stretches to accommodate within its confines the expanded volume of the swollen base responsive water swellable polymer layer.

7. The method according to claim 6, wherein the basic aqueous environment comprises one or more of an alkali metal base, ammonium hydroxide, alkaline earth metal base or an aliphatic amine.

8. The method according to claim 6 further comprising crosslinking the stretched extensible, water and base permeable polymer layer.

9. The method according to claim 6 further comprising removing from the polymer encapsulated particulate material water within the swollen base responsive water swellable polymer layer, the effect of which causes the volume of that layer to be reduced, wherein the extensible, water and base permeable polymer layer remains in a stretched state so as to provide one or more voids in between the particulate material and the stretched extensible, water and base permeable polymer layer.

10. A method of preparing a paint, filler, adhesive, liquid ink, primer or sealant product comprising preparing an aqueous dispersion of polymer encapsulated particulate material according to claim 1, and combining the dispersion with one or more formulation components.

11. Polymer encapsulated particulate material, the particulate material being encapsulated by a base responsive water swellable non-living polymer layer comprising polymerised residue of ionisable ethylenically unsaturated monomer, wherein the base responsive water swellable non-living polymer layer is encapsulated by an extensible, water and base permeable non-living polymer layer that comprises polymerised residue of non-ionisable ethylenically unsaturated monomer.

12. The polymer encapsulated particulate material according to claim 11, wherein the water swellable non-living polymer layer comprises the polymerised residue of from about 10 wt % to about 40 wt % ionisable ethylenically unsaturated monomer.

13. The polymer encapsulated particulate material according to claim 11, wherein the extensible, water and base permeable non-living polymer layer comprises the polymerised residue of greater than about 70 wt % of non-ionisable hydrophobic ethylenically unsaturated monomer.

14. The polymer encapsulated particulate material according to claim 11, wherein the water swellable non-living polymer layer has an average thickness of at least about 10 nm.

15. The polymer encapsulated particulate material according to claim 11, wherein the extensible, water and base permeable non-living polymer layer has an average thickness of at least about 70 nm.

16. The polymer encapsulated particulate material according to claim 11, wherein the water swellable non-living polymer layer represents no more than about 15 wt % of the combined mass of the water swellable non-living polymer layer and the extensible, water and base permeable non-living polymer layer.

17. The polymer encapsulated particulate material according to claim 11, wherein the extensible, water and base permeable non-living polymer layer represents at least about 85 wt % of the combined mass of the water swellable non-living polymer layer and the extensible, water and base permeable non-living polymer layer.

18. The polymer encapsulated particulate material according to claim 11, wherein the base responsive water swellable non-living polymer layer is swollen with water to provide for an expanded volume of that layer, and the extensible, water and base permeable non-living polymer layer is in a stretched state to accommodate within its confines the expanded volume of the swollen base responsive water swellable non-living polymer layer.

19. The polymer encapsulated particulate material according to claim 18, wherein the stretched extensible, water and base permeable non-living polymer layer is crosslinked.

20. The polymer encapsulated particulate material according to claim 18, wherein water within the swollen base responsive water swellable non-living polymer layer of the polymer encapsulated particulate material has been removed and the volume of that layer is reduced, and wherein the extensible, water and base permeable non-living polymer layer remains in a stretched state so as to provide one or more voids in between the particulate material and the stretched, extensible, water and base permeable non-living polymer layer.