Apparatus and Method for Quantatively Measuring Liquid Film Drying Rates on Substrates

Abstract

An apparatus and method for measuring the drying rate of a liquid or liquid film in air or other gaseous media by either: a) measuring changes in the print density of the liquid; b) measuring changes in the dynamic surface tension of the liquid; c) measuring the differential pressure between an inert gas required to displace a sample of the liquid drawn into a capillary tube from a reservoir of the liquid and the pressure required for a bubble of the gas to form in the reservoir; and d) measuring the electrical conductance or resistance of the liquid.

1 - 11 . (canceled) 
     
     
         12 . An apparatus for determining the drying rate of a liquid, comprising:
 container means for containing a volume of the liquid;   a capillary tube, having a predetermined diameter, and first and second opposite open ends, such that a first end of the capillary tube is capable of being immersed in the volume of said liquid;   an inert gas source for supplying a flow of an inert gas that is not chemically reactive with said liquid, said inert gas source being connected to said second open end of said capillary tube; and   pressure-sensing means for measuring a pressure of said flow of said inert gas, and clock means for measuring a length of time, that is required to force an amount of said liquid, that has been drawn from said volume of said liquid in said container into said capillary tube through said first open end of said capillary tube by capillary action, after said first open end of said capillary tube has been immersed into said volume of said liquid, from said capillary tube and for a bubble of said inert gas to form in said container means containing said volume of said liquid whose drying rate is being measured.   
     
     
         13 . An apparatus of  claim 12  wherein a second capillary tube is included. 
     
     
         14 . A method for determining the drying rate of a liquid film, comprising:
 (a) providing a container holding a volume of the liquid;   (b) providing a capillary tube, having a predetermined diameter, and first and second opposite open ends, such that said first end of said capillary tube is capable of being inserted into said container;   (c) providing a source for supplying an inert gas that is not reactive with said liquid whose drying rate is being determined, connected to said second open end of said capillary tube;   (d) immersing said first open end of said capillary tube into said container holding said volume of said liquid whose drying rate is being determined, so as to cause an amount of said liquid to be drawn into said first open end of said capillary tube by capillary action;   (e) causing an amount of said inert gas, of measured pressure, to flow into said second open end of said capillary tube, simultaneously with (d), and measuring a length of time until said amount of liquid in said capillary tube has been forced out therefrom and a bubble of said inert gas is detected in said container holding said volume of said liquid;   (f) repeating steps (d) and (e); and   (g) determining the drying rate of said liquid from measurements of the lengths of time and increases in pressure required, from one measurement to a subsequent measurement, of said inert gas that is required to force said liquid out from said first open end of said capillary tube and for said bubble of said inert gas to form in said container of said liquid.   
     
     
         15 . The method of  claim 14  wherein a second capillary tube is included. 
     
     
         16 . An apparatus for determining the drying rate of a liquid film, comprising at least one pair of electrodes in contact with the liquid film; said electrodes connected to a device capable of measuring electrical conductance or resistance of the liquid film. 
     
     
         17 . The apparatus according to  claim 16  wherein the liquid is selected from the group consisting of coatings, inks, paints, lacquers or adhesives. 
     
     
         18 . The apparatus according to  claim 17 , wherein the liquid is an ink. 
     
     
         19 . The apparatus according to  claim 16 , wherein when the liquid film thickness ranges from 0.001 mm to 5.0 mm. 
     
     
         20 . The apparatus according to  claim 16 , wherein the pair of electrodes is selected from the group consisting of conductive metal, conductive soft rubber, elastomer, adhesive or high viscosity liquid. 
     
     
         21 . The apparatus according to  claim 20 , wherein the conductive metal is-aluminum foil. 
     
     
         22 . The apparatus according to  claim 16 , further comprising a non-conductive material on which is disposed the electrodes. 
     
     
         23 . The apparatus according to  claim 22 , wherein the non-conductive material is glass. 
     
     
         24 . The apparatus of  claim 22  wherein the non-conductive material serves as a substrate for the liquid film and has electrodes embedded therein. 
     
     
         25 . The apparatus according to  claim 24 , wherein the electrodes individually are about 1 cm to about 30 cm in length. 
     
     
         26 . The apparatus according to  claim 24 , wherein the electrodes are spaced between 0.1 mm to 200 mm from each other. 
     
     
         27 . A method for determining the drying rate of a liquid film, comprising:
 (a) applying the liquid film onto a substrate;   (b) bringing said liquid film into contact with at least one pair of electrodes connected to a device capable of measuring the electrical conductance or resistance of the liquid film; and   (c) determining the drying rate of the liquid film by graphical correlation of the electrical conductance or resistance measurements of the liquid film.   
     
     
         28 . The method according to  claim 27 , further comprising the step of curing the liquid with an actinic radiation source prior to step (c). 
     
     
         29 . The method according to  claim 28 , wherein the actinic radiation source is ultraviolet light. 
     
     
         30 . The method according to  claim 27 , wherein the liquid film is selected from the group consisting of coatings, inks, paints, lacquers or adhesives. 
     
     
         31 . The method according to  claim 27 , wherein the liquid film is an ink. 
     
     
         32 . The method according to  claim 27 , wherein when the liquid film thickness ranges from 0.001 mm to 5.0 mm. 
     
     
         33 . The method according to  claim 27 , wherein the pair of electrodes is selected from the group consisting of conductive metal, conductive soft rubber, elastomer, adhesive or high viscosity liquid. 
     
     
         34 . The method according to  claim 31 , wherein the conductive metal is aluminum foil. 
     
     
         35 . The method according to  claim 27 , wherein the electrodes are disposed on a non-conductive material. 
     
     
         36 . The method according to  claim 33 , wherein the non-conductive material is glass. 
     
     
         37 . The method of  claim 33 , wherein the non-conductive material serves as a substrate for the liquid film and has electrodes embedded therein. 
     
     
         38 . The method according to  claim 35 , wherein the electrodes individually are about 1 cm to about 30 cm in length. 
     
     
         39 . The method according to  claim 35 , wherein the electrodes are spaced between 0.1 mm to 200 mm from each other.