# US 11,078,368 B2 · Acrylate coating compositions comprising a UV light cleavable cross-linking agent

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- Number: US 11,078,368 B2
- Document ID: US11078368B2
- Status: Granted
- Kind: B2
- Application number: 16/122,364
- Filed: 2018-09-05
- Published: 2019-03-07
- Granted: 2021-08-03
- Earliest claimed: 2017-09-06
- Assignees: Monash University
- Applicants: Monash University
- Inventors: Mustafa Abdallh; Milton Thomas William Hearn; George Simon; Kei Saito
- Web page: https://patentgrep.com/patent/US11078368B2

## CPC

- C09D 4/00: 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}
- C08F 120/12: of monohydric alcohols or phenols
- C08F 120/14: Methyl esters {, e.g. methyl (meth)acrylate}
- C09D 5/00: Coating compositions, e.g. paints, varnishes or lacquers, characterised by their physical nature or the effects produced {(electrically insulating plastics, resins or waxes H01B3/30)}; Filling pastes
- C09D 5/32: Radiation-absorbing paints {(protection against X-, gamma- or corpuscular radiation G21F)}
- C09D 7/40: Additives
- C09D 133/06: of esters containing only carbon, hydrogen and oxygen, the oxygen atom being present only as part of the carboxyl radical
- C09D 133/10: Homopolymers or copolymers of methacrylic acid esters
- C08F 2810/20: leading to a crosslinking, either explicitly or inherently
- C09D: COATING COMPOSITIONS, e.g. PAINTS, VARNISHES OR LACQUERS; FILLING PASTES; CHEMICAL PAINT OR INK REMOVERS; INKS; CORRECTING FLUIDS; WOODSTAINS; PASTES OR SOLIDS FOR COLOURING OR PRINTING; USE OF MATERIALS THEREFOR (cosmetics A61K; processes for applying liquids or other fluent materials to surfaces, in general, B05D; staining wood B27K5/02; glazes or vitreous enamels C03C; natural resins, French polish, drying-oils, driers, turpentine, per se, C09F; polishing compositions other than French polish, ski waxes C09G; adhesives or use of materials as adhesives C09J; materials for sealing or packing joints or covers C09K3/10; materials for stopping leaks C09K3/12; processes for the electrolytic or electrophoretic production of coatings C25D)
- C08F: MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS

## 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.

## Claims

### Claim 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.

### Claim 2 (depends on 1)

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.

### Claim 3 (depends on 1)

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.

### Claim 4 (depends on 3)

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.

### Claim 5 (depends on 1)

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

### Claim 6 (depends on 1)

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

### Claim 7 (depends on 1)

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

### Claim 8 (depends on 1)

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

### Claim 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.

### Claim 10 (depends on 9)

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.

### Claim 11 (depends on 9)

A coating prepared by the process of claim 9.

### Claim 12 (depends on 1)

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.

### Claim 13 (depends on 12)

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.

### Claim 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.

### Claim 15 (depends on 14)

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

### Claim 16 (depends on 14)

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

### Claim 17 (depends on 14)

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.

### Claim 18 (depends on 14)

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.

### Claim 19 (depends on 18)

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

### Claim 20 (depends on 18)

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.