Methods of making coated substrates having block resistance

Patent metadata

Field	Value
Publication number	US-12528951-B2
Application number	US-202118002503-A
Country	US
Kind code	B2
Filing date	Sep 27, 2021
Priority date	Sep 30, 2020
Publication date	Jan 20, 2026
Grant date	Jan 20, 2026

Abstract

The present invention provides methods of making block resistant coated substrates, such as boards, sheets, panels, tiles, assemblies or membranes for use in building and construction, such as for exterior use, the methods comprising coating a substrate with a coating composition of one or more aqueous emulsion polymers and one or more photoinitiators, such as a hydrogen abstraction initiator, onto the substrate to form a coated substrate, at least partially curing or drying the coating, and exposing the at least partially cured coating on the coated substrate to UV light to cause the photoinitiator to react with itself or with the coating composition. In the methods, the wavelength of the UV light used preferably matches or at least overlaps the spectral activation or excitation window of the one or more photoinitiators.

First claim

The invention claimed is:

1 . A method of making a block resistant coated substrate,
wherein the method comprises:
at least partially coating the substrate with an aqueous coating composition to form an aqueous coating layer, the aqueous coating composition having in it one or more photoinitiators;
drying the aqueous coating layer to form a coated substrate; and,
exposing the coated substrate to ultraviolet (UV) light, thereby causing the coating to develop block resistance and form a block resistant coated substrate; and
wiping the block resistant coated substrate with a polar solvent to improve the block resistance,
wherein the coating on the coated substrate is fully dried prior to the exposing; wherein the aqueous coating composition consists of one or more metastable aqueous emulsion copolymers, in copolymerized form, of one or more of butyl acrylate (BA), 2-ethylhexyl acrylate (2-EHA), ethyl acrylate (EA), dodecyl methacrylate or octadecyl methacrylate copolymerized with butyl methacrylate (BMA) and/or methyl methacrylate (MMA) with, in copolymerized form, an acid and/or hydroxyl group containing monomer; one or more photoinitiators; surfactants or emulsifiers; water; and one or more optional ingredients selected from biocides, insecticides, insect repellants, rheology modifiers, extenders, opacifying pigments, colorants, fly ash, dispersants, defoamers, UV stabilizers, colorants, fire retardants, pH adjusters or buffers, coalescents, glass fibers, carbon fibers, microbeads, anti-freeze agents, infrared-reflective material, and materials that impart freeze-thaw stability; and wherein the amount of the acid and/or hydroxyl group containing monomer ranges from 0.3 to 2.0 wt. %.

2 . The method as claimed in claim 1 , wherein the one or more photoinitiators is chosen from a hydrogen abstraction initiator or another initiator that reacts or that becomes activated in the presence of UV light.

3 . The method as claimed in claim 2 , wherein the one or more photoinitiators is a benzophenone group containing or a xanthone group containing initiator.

4 . The method as claimed in claim 1 , wherein the exposing the coated substrate to UV light comprises exposing the coated substrate to UV light energy having a wavelength that matches the spectral activation window of at least one of the one or more photoinitiators.

5 . The method as claimed in claim 4 , wherein in the exposing the coated substrate to UV light, the amount of UV light energy having a wavelength that matches the spectral activation window of the one or more photoinitiators to which the coated substrate is exposed ranges from 3.5 to 30 J/cm 2 .

6 . The method as claimed in claim 1 , wherein the polar solvent is an alkanol.

7 . The method as claimed in claim 1 , wherein the substrate is a board and wherein the method further comprises, if needed, completing the curing or drying of the coating on the block resistant coated substrate and then stacking another board, or coated or uncoated substrate onto the block resistant coated substrate.

8 . The method as claimed in claim 1 , wherein the one or more metastable aqueous emulsion copolymers have ambient film-forming properties and have a calculated glass transition temperature (calculated Tg) of from −100 to 60° C.

9 . The method of claim 1 , wherein wiping comprises wiping the surface of the block resistant coated substrate using an isopropyl alcohol wet wipe.

Assignees

• Rohm & Haas

Inventors

• Szewczyk Janah C
• Williams Drew E
• Faber Katherine A
• Bowe Michael D

Classifications

• C09D7/63

  organic · CPC title

• C09D7/20

  Diluents or solvents · CPC title

• C09D133/08

  Homopolymers or copolymers of acrylic acid esters · CPC title

• C09D5/16 Primary

  Antifouling paints; Underwater paints · CPC title

• C08F2/48 Primary

  by ultraviolet or visible light · CPC title