High performance aqueous coating compositions

• US 7,812,090 B2
• Filed: 08/15/2008
• Issued: 10/12/2010
• Est. Priority Date: 06/02/2006
• Status: Active Grant

• Current Assignee: Swimc, LLC (The Sherwin-Williams Company)
• Original Assignee: Valspar Sourcing, Inc. (Sherwin-Williams Company)
• Inventors: Killilea, T. Howard, Wildman, Michael C., Johnson, Bruce A., Weber, Carl H.
• Primary Examiner(s): Sastri; Satya B
• Application Number:
  US12/192,929
• Publication Number:
  US 20090035587A1
• Time in Patent Office: 788 Days
• Field of Search: 524/818, 524/806, 525/902, 428/447
• US Class Current: 524/818
• 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 230/085 the monomer being a polymerisable silane, e.g. (meth)acryloyloxy trialkoxy silanes or vinyl trialkoxysilanes
• CPC Class Codes: C08L 2312/08 by silane
• CPC Class Codes: C09D 133/02 Homopolymers or copolymers of acids; Metal or ammonium salts thereof
• CPC Class Codes: Y10S 525/902 Core-shell
• CPC Class Codes: Y10T 428/31663 As siloxane, silicone or silane

Abstract

Coating compositions for cementitious substrates may be made from a silane-functional multistage latex polymer. The compositions adhere well to cementitious substrates and resist crush damage such as may be caused by stacking coated substrate boards.

Claims

1. A coating composition, comprising a silane-functional, acetoacetoxy-functional multistage latex polymer, wherein the multistage latex polymer comprises at least one silane-functional soft stage having a Tg between about −

65 and 30°

C. and at least one hard stage having a Tg between about 30 and about 230°

C.

2. The composition of claim 1, wherein the multistage latex polymer is formed by chain-growth polymerization in the presence of a silane coupling agent containing a functional group capable of copolymerizing with a monomer from which the multistage latex polymer is formed.

3. The composition of claim 2, wherein the silane coupling agent contains an ethylenically unsaturated group.

4. The composition of claim 2, wherein the silane coupling agent comprises a vinyl silane.

5. The composition of claim 2, wherein the silane coupling agent comprises a mercapto silane.

6. The composition of claim 2, wherein the silane-functional multistage polymer contains about 0.2 to about 10 weight % silane, based on a comparison of silane coupling agent weight to latex polymer weight.

7. The composition of claim 1, wherein the multistage latex polymer is made silane-functional by reacting an already-formed multistage latex polymer with a silane coupling agent having a functional group which reacts with the already-formed polymer.

8. The composition of claim 7, wherein the silane coupling agent comprises an epoxy silane.

9. The composition of claim 7, wherein the silane coupling agent comprises an amino silane.

10. The composition of claim 7, wherein the silane-functional multistage polymer contains about 0.2 to about 10 weight % silane, based on a comparison of silane coupling agent weight to latex polymer weight.

11. The composition of claim 1, wherein the multistage latex polymer comprises 50 to 90 weight % soft stage polymer morphology having a Tg between about −

5 and 25°

C. and 10 to 50 weight % hard stage polymer morphology having a Tg between about 30 and 105°

C., based on total polymer weight.

12. The composition of claim 1, wherein the multistage latex polymer has a gradient Tg.

13. The composition of claim 1, wherein the composition contains less than 4% volatile organic compounds (VOCs).

14. The composition of claim 1, wherein the composition has a minimum film forming temperature less than about 20°

C.

15. The composition of claim 1, wherein the composition when dried or otherwise hardened has a total thickness between about 10 and about 150 micrometers.

16. The composition of claim 1, wherein the composition when applied to embossed fiber cement board substrates and dried or otherwise hardened has a Crush Resistance value of at least 3 when two thus-coated substrates are placed face-to-face and subjected to a pressure of about 8 kg/cm².

17. A method for preparing a coated article, which method comprises providing a cementitious substrate, coating at least a portion of the substrate with an aqueous coating composition comprising a silane-functional acetoacetoxy-functional multistage latex polymer, comprising at least one silane-functional soft stage having a Tg between about −

65 and 30°

C. and at least one hard stage having a Tg between about 30 and about 230°

C., and allowing the coating composition to harden.

18. A coated article comprising a cementitious substrate having at least one major surface on which is coated a layer comprising an aqueous coating composition comprising a silane-functional acetoacetoxy-functional multistage latex polymer wherein the multistage latex polymer comprises at least one silane-functional soft stage having a Tg between about −

65 and 30°

C. and at least one hard stage having a Tg between about 30 and about 230°

C.