Process for preparing articles having anti-fog layer by layer coating and coated articles having enhanced anti-fog and durability properties
View Patent ↗Disclosed are processes for preparing articles having anti-fog properties, comprising providing a substrate having at least one main surface coated with an intermediate coating obtained by applying and at least partially curing an intermediate coating composition comprising at least one monoepoxysilane and/or an hydrolyzate thereof and at least one polyepoxy monomer comprising at least two epoxy groups, forming onto said intermediate coating at least one bi-layer, and curing said at least one bi-layer by heating at a temperature of 150° C. or less at atmospheric pressure and in the absence of added water steam. Also disclosed are articles made and/or makeable by these processes.
1. A process for preparing an article having anti-fog properties, comprising:
a) providing a substrate having at least one main surface coated with an intermediate coating obtained by applying and at least partially curing an intermediate coating composition comprising at least one monoepoxysilane and/or an hydrolyzate thereof and at least one polyepoxy monomer comprising at least two epoxy groups;
b) forming onto said intermediate coating at least one bi-layer obtained by:
b1—forming a first layer by applying a first layer composition on said intermediate coating, said first layer composition comprising at least one compound A having a first electric charge,
b2—forming a second layer by applying a second layer composition directly on said first layer, said second layer composition comprising at least one compound B having a second electric charge which is opposite to said first electric charge,
compounds A and B being independently chosen from polyelectrolytes, SiO 2 nanoparticles comprising ionic groups and TiO 2 nanoparticles comprising ionic groups, with the proviso that at least one of said first and said second layer comprises SiO 2 nanoparticles comprising ionic groups and/or TiO 2 nanoparticles comprising ionic groups; and
c) curing said at least one bi-layer by heating at a temperature of 150° C. or less, at atmospheric pressure and in the absence of added water steam.
2. The process of claim 1 , wherein at least one of said first and said second layer comprises SiO 2 nanoparticles comprising ionic groups.
3. The process of claim 1 , wherein the at least one bi-layer is cured by heating at a temperature of 120° C. or less, at atmospheric pressure and in the absence of added water steam.
4. The process of claim 1 , wherein one of the layers of said at least one bi-layer comprises SiO 2 nanoparticles comprising ionic groups and the other layer of said at least one bi-layer comprises at least one oppositely charged polyelectrolyte.
5. The process of claim 4 , wherein the SiO 2 nanoparticles comprising ionic groups are positively charged.
6. The process of claim 5 , wherein the SiO 2 nanoparticles comprising ionic groups are obtained from nanoparticles functionalized by amino groups.
7. The process of claim 6 , wherein the SiO 2 nanoparticles comprising ionic groups are obtained from 3-aminopropylsilane modified SiO 2 nanoparticles.
8. The process of claim 5 , wherein the polyelectrolyte is negatively charged.
9. The process of claim 8 , wherein the polyelectrolyte is obtained from a polymer further defined as a polyacrylic acid, sulfonated polystyrene, sulfonated polyvinylic compound or a mixture thereof.
10. The process of claim 4 , wherein the SiO 2 nanoparticles comprising ionic groups are negatively charged.
11. The process of claim 10 , wherein the polyelectrolyte is positively charged.
12. The process of claim 11 , wherein the polyelectrolyte is a polymer further defined as a poly(diallyl dimethylammonium chloride), poly(allylamine hydrochloride), poly(4-vinylbenzyltrimethyl ammonium chloride) or a mixture thereof.
13. The process of claim 1 , wherein the monoepoxysilane is a compound of formula:
R n′ YSi(X) 3−n′ (I)
or a hydrolyzate thereof, in which the R groups are identical or different and represent monovalent organic groups linked to the silicon atom through a carbon atom, Y is a monovalent organic group linked to the silicon atom through a carbon atom and containing one epoxy function, the X groups are identical or different and represent hydrolyzable groups or hydrogen atoms, and n′ is 0 or 1.
14. The process of claim 1 , wherein the polyepoxy monomer is further defined as a glycerol propoxylate triglycidyl ether, trimethylolpropane triglycidyl ether, or a mixture thereof.
15. The process of claim 1 , wherein the polyepoxy monomer has two to four epoxy groups.
16. The process of claim 15 , wherein the polyepoxy monomer is present in the intermediate coating composition in an amount ranging from 0.5 to 40% by weight relative to the weight of the dry extract of said intermediate coating composition.
17. The process of claim 1 , wherein said intermediate coating composition further comprises at least one inorganic filler.
18. The process of claim 1 , wherein the thickness of said intermediate coating ranges from 50 nm to 20 microns.
19. The process of claim 1 , wherein each layer of said at least one bi-layer is rinsed with an aqueous rinsing solution after having been deposited.
20. The process of claim 1 , wherein the intermediate coating is coated with a plurality of said bi-layers stacked onto each other, with the proviso that the second electric charge of the at least one compound B comprised in the second layer of each bi-layer is opposite to the first electric charge of the at least one compound A comprised in the first layer of the subsequent bi-layer.