High temperature polymer filtration medium
View Patent ↗A filter medium for use in particulate filtering applications is disclosed. The filter medium is formed from a substrate capable of retaining the desired physical structure of the filter medium under the conditions of the filtering application, including temperature. A polyimide based stiffening agent adapted for treating the substrate is also provided.
1. A method of making a filter medium for use in a filtering application at an application temperature comprising:
providing a substrate;
providing a polyimide stiffening agent in solution selected from the group consisting of polyetherimides and polybismaleimides;
diluting the polyimide stiffening agent solution to approximately 5.5% solids;
treating the substrate with the polyimide stiffening agent solution;
curing the treated substrate; and
pleating the treated substrate, after curing the treated substrate, at a temperature above the application temperature, wherein the application temperature is greater than about 375° F.;
wherein the treated substrate with the polyimide stiffening agent is capable of withstanding at least 100,000 cleaning pulses at a temperature of about 375° F., a flowrate of about 1200 cubic feet per minute, and a pressure of about 60 psi.
2. The method of claim 1 , further including calendering the substrate after the step of providing a substrate and before the step of treating the substrate.
3. The method of claim 1 , wherein the substrate is selected from the group consisting of polyarylene sulfides, aramides, polyimides, glass, acrylics, pre-oxidized acrylics and mixtures thereof.
4. The method of claim 1 , wherein the polyimide stiffening agent is about 2% to about 20% by weight of the total weight of the filter medium.
5. A method of making a filter medium for use in a filtering application at an application temperature comprising:
providing a polymer substrate;
calendering the polymer substrate;
providing a polyimide stiffening agent in solution selected from the group consisting of polyetherimides and polybismaleimides;
diluting the polyimide stiffening agent solution to approximately 5.5% solids;
treating the calendered polymer substrate with the polyimide stiffening agent solution;
curing the treated polymer substrate; and
pleating the treated substrate, after curing the treated substrate, at a temperature of about 430° F., wherein the treated polymer substrate with the polyimide stiffening agent is capable of withstanding at least 100,000 cleaning pulses at a temperature of about 375° F., a flowrate of about 1200 cubic feet per minute, and a pressure of about 60 psi.
6. The method of claim 5 , wherein the polymer substrate is selected from the group consisting of polyarylene sulfides, aramides, polyimides, acrylics, preoxidized acrylics and mixtures thereof.
7. The method of claim 5 , wherein the polyimide stiffening agent is about 2% to about 20% by weight of the total weight of the filter medium.
8. The method of claim 5 , wherein the application temperature is greater than about 375° F.