High temperature and high humidity release coating for polymer film
The present invention relates to a process for coating a surface of a polymer film with a release coating composition to provide a release film for use in high temperature and/or high humidity conditions, which comprises coating at least one surface of the polymer film with an aqueous of from about 0.2 to about 6.0% by weight of at least one hydroxypropyl methyl cellulose having hydroxypropyl molar substitution of from 0 to about 0.82 and from about 1% to about 35% by weight of alcohol to provide a coating weight of at least about 0.004 lb/ream per side and drying the coated film to set the coating. Also disclosed is a release polymer film coated on at least one surface with a composition comprising from about 0.2 to about 6.0% by weight of at least one hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 and the coating weight is at least about 0.004 lb/ream.
1 . A process for coating a surface of a polymer film with a release coating composition to provide a release film for use in high temperature and/or high humidity conditions, which comprises coating at least one surface of the polymer film with an aqueous of from about 0.2 to about 6.0% by weight of at least one hydroxypropyl methyl cellulose having hydroxypropyl molar substitution of from 0 to about 0.82 and from about 1% to about 35% by weight of alcohol to provide a coating weight of at least about 0.004 lb/ream per side and drying the coated film to set the coating.
2 . A process as claimed in claim 1 , wherein a low viscosity hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 in water, wherein low viscosity means the viscosity of a 2% by weight solution of hydroxypropyl methylcellulose in water at room temperature (20° C.) is up to 100 centipoise is used.
3 . A process as claimed in claim 2 , wherein up to about 3% by weight of high viscosity hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 in water, wherein high viscosity means the viscosity of a 2% by weight solution of hydroxypropyl methylcellulose in water at room temperature (20° C.) is from 100 to 100,000 centipoise is used.
4 . A process as claimed in claim 1 , wherein the film is coated on both sides in separate or single passes to achieve the desired coating weight.
5 . A release polymer film coated on at least one surface with a composition comprising from about 0.2 to about 6.0% by weight of at least one hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 and the coating weight is at least about 0.004 lb/ream.
6 . A release polymer film as claimed in claim 5 , wherein a low viscosity hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 in water, wherein low viscosity means the viscosity of a 2% by weight solution of hydroxypropyl methylcellulose in water at room temperature (20° C.) is up to 100 centipoise is present.
7 . A release polymer film as claimed in claim 5 , wherein up to about 3% by weight of high viscosity hydroxypropyl methylcellulose having hydroxypropyl molar substitution of from 0 to about 0.82 in water, wherein high viscosity means the viscosity of a 2% by weight solution of hydroxypropyl methylcellulose in water at room temperature (20° C.) is from 100 to 100,000 centipoise is present.
8 . A release polymer film as claimed in claim 3 , wherein the coating weight is at least about 0.2 lb/ream per surface.
9 . A release polymer film as claimed in claim 5 , wherein the ratio of particulate solid to hydroxypropyl methylcellulose is in the range of from about 0.01 to about 1.5.
10 . A release polymer film as claimed in claim 5 , wherein the polymer film is selected from the group comprising polyolefins, polyesters, nylons and combinations thereof.
11 . A release polymer film as claimed in claim 5 , wherein the nylons are selected from Nylon 66 and Nylon 6 films.
12 . A release polymer film as claimed in claim 5 , wherein the polymer film is monoaxially or biaxially oriented.