Acrylate coating compositions comprising a UV light cleavable cross-linking agent

Patent metadata

Field	Value
Publication number	US-11078368-B2
Application number	US-201816122364-A
Country	US
Kind code	B2
Filing date	Sep 5, 2018
Priority date	Sep 6, 2017
Publication date	Aug 3, 2021
Grant date	Aug 3, 2021

Abstract

The present disclosure provides a coating composition for forming a coating that at least partially mobilizes in response to UV light, the composition comprising a monomer selected from acrylates, methacrylates and mixtures thereof, a cross-linking agent comprising two sub-units covalently bonded together, each sub-unit comprising an unsaturated group which is co-polymerisable with the monomer, wherein the two sub-units are adapted to dissociate in response to irradiation by UV light. The cross-linking agent may be present in the coating composition in an amount of less than 15 mol % of the total of the monomer and cross-linking agent.

First claim

The invention claimed is:

1. A coating composition for forming a coating that at least partially mobilises in response to UV light, the composition comprising:
a monomer selected from the group consisting of acrylates, methacrylates and mixtures thereof,
a cross-linking agent comprising two sub-units covalently bonded together, each sub-unit comprising an unsaturated group which is co-polymerisable with the monomer,
wherein the two sub-units are adapted to dissociate in response to irradiation by UV light, and
wherein the cross-linking agent is present in the coating composition in an amount of less than about 15 mol % of the total of the monomer and cross-linking agent.

2. The coating composition according to claim 1 , wherein the two sub-units are adapted to dissociate by a cycloelimination reaction in response to irradiation by UV light.

3. The coating composition according to claim 1 , wherein the cross-linking agent is a [2π+2π] cycloaddition dimer or a [4π+4π] cycloaddition dimer of the two sub-units.

4. The coating composition according to claim 3 , wherein the cross-linking agent comprises a dimer of coumarin, thymine, stilbene, cinnamic acid, anthracene, or derivatives or combinations thereof.

5. The coating composition according to claim 1 , wherein the unsaturated group is selected from the group consisting of acryloyloxy and methacryloyloxy.

6. The coating composition according to claim 1 , wherein the cross-linking agent has a structure of Formula I:

7. The coating composition according to claim 1 , further comprising a radical polymerisation initiator.

8. The coating composition according to claim 1 , wherein a coating formed by polymerising the coating composition has a T g of at least about 45° C., and wherein irradiation of the coating by UV light at about 254 nm provides a reduction of T g of at least about 3° C.

9. A process for coating a substrate with a coating that at least partially mobilises in response to UV light, the process comprising:
providing a substrate to be coated,
providing a monomer selected from the group consisting of acrylates, methacrylates and mixtures thereof,
providing a cross-linking agent comprising two sub-units covalently bonded together, each sub-unit comprising an unsaturated group which is co-polymerisable with the monomer, wherein the two sub-units are adapted to dissociate in response to irradiation by UV light,
contacting the substrate with the monomer and the cross-linking agent, wherein the cross-linking agent is in an amount of less than about 15 mol % of the total of the monomer and cross-linking agent, and
inducing co-polymerisation of the monomer and the cross-linking agent to form a polymer.

10. The process of claim 9 , wherein the substrate is selected from the group consisting of a glass substrate, a metallic substrate, a polymeric substrate and a ceramic substrate, and combinations thereof.

11. A coating prepared by the process of claim 9 .

12. A coating formed by applying the coating composition according to claim 1 to a substrate, and inducing polymerisation of the coating composition to form a polymer.

13. The coating of claim 12 , wherein the substrate is selected from the group consisting of a glass substrate, a metallic substrate, a polymeric substrate and a ceramic substrate, and combinations thereof.

14. A coating that at least partially mobilises in response to UV light, comprising:
a polymer comprising a monomer selected from the group consisting of acrylates, methacrylates and mixtures thereof and cross-linked by cross-linking groups,
wherein the cross-linking groups comprise two sub-units covalently bonded together and adapted to dissociate by a cycloelimination reaction in response to irradiation by UV light to form pendant unsaturated groups,
wherein the cross-linking groups are present in the polymer in an amount of less than about 15 mol % of the total of the monomer and cross-linking groups, and
wherein the polymer, prior to irradiation by the UV light, comprises less than about 5 mol % of the pendant unsaturated groups relative to the cross-linking groups.

15. The coating of claim 14 having a T g of at least 45° C., wherein irradiation of the coating by UV light at about 254 nm provides a reduction of T g of at least about 3° C.

16. The coating of claim 14 having a T g of at least 100° C., wherein irradiation of the coating by UV light at about 254 nm provides a reduction of T g of at least about 10° C.

17. A coating according to claim 14 , wherein a surface defect in the coating is treatable by irradiating the coating with UV light to at least partially mobilise the coating.

18. A process for healing a surface defect in the coating according to claim 14 , comprising:
irradiating the coating in a region around the defect with UV light with a wavelength below about 300 nm to at least partially mobilise the coating; and
allowing polymer in the at least partially mobilised coating to flow into the defect.

19. The process of claim 18 , wherein the coating is heated to above a T g of the polymer while irradiating the coating.

20. The process of claim 18 , comprising an additional step of irradiating the coating in the region around the defect with UV light with a wavelength above about 300 nm to immobilise the coating in the region around the defect.

Assignees

• Univ Monash

Inventors

• Abdallh Mustafa
• Hearn Milton Thomas William
• Simon George
• Saito Kei

Classifications

• C09D7/40

  Additives · CPC title

• C09D5/32

  Radiation-absorbing paints {(protection against X-, gamma- or corpuscular radiation G21F)} · CPC title

• C09D4/00 Primary

  Coating compositions, e.g. paints, varnishes or lacquers, based on organic non-macromolecular compounds having at least one polymerisable carbon-to-carbon unsaturated bond {; Coating compositions, based on monomers of macromolecular compounds of groups C09D183/00 - C09D183/16} · CPC title

• C09D133/10

  Homopolymers or copolymers of methacrylic acid esters · CPC title

• C09D133/06

  of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical · CPC title