Claims for Patent: 4,620,932

Summary for Patent: 4,620,932

Title:	Submicronic hydrophilic filter media
Abstract:	The present invention is a one-piece construction sub-micronic filter media capable of high volume filtration of sub-micronic sized particulate from fluids without the addition of wetting agents, solvents, added electrical charge enhancers, or elevated pressure differentials, which includes a continuous matrix having an initial micron rating of from about 1 to about 5 microns. The continuous matrix is impregnated with a hydrophilic terpolymer by step-wise addition of low viscosity terpolymerization mixture including 10% to 14% by weight of a polymer which includes at least one of alkyl acrylate and alkyl methacrylate and acrylic acid. The terpolymeric mixture also includes 17 to about 20% by weight of polyethyleneimine and urea solution, from about 7 to about 10% ammonia and from about 2 to about 6% by weight epoxy resin. The polymerization mixture has a solids content of from about 16 to about 20% by weight prior to polymerization. The step-wise addition by which the matrix is impregnated includes saturating the matrix material with the terpolymeric mixture followed by compressing the saturated material and repeating the saturation compressing at least one additional time followed by drying the saturated matrix.
Inventor(s):	Howery; Kenneth A. (South Orange, NJ)
Assignee:
Application Number:	06/651,513
Patent Claims:	1. An essentially one-piece construction submicronic filter medium capable of high volume filtration of submicronic size particulate from fluids in the substantial absence of (1) added wetting agents and solvents, (2) added electrical charge enhancers, and (3) elevated pressure differentials comprising: a continuous matrix material having an initial micron rating of from about 1 to about 5 microns; a hydrophilic terpolymer impregnated on said matrix material by step-wise addition of a low-viscosity terpolymeric polymerization mixture comprising from 10% to about 14% by weight of a polymer which includes at least one of alkylacrylate and alkylmethacrylate and acrylic acid; from about 17% to about 22% by weight polyethyleneimine and urea solution; from about 7% to about 10% by weight ammonia; and from about 2% to about 6% by weight epoxy resin, said polymerization mixture having a solids content of from about 15% to about 20% by weight prior to polymerization, said step-wise addition comprising saturation of said matrix material with said terpolymeric mixture followed by compressing said saturated matrix material, and repeating said saturation and compressing at least one additonal time until the saturated weight of the said matrix is from about 4 to about 6 times the dry weight per cubic inch of matrix, and drying said saturated matrix material in a first stage drying in which the moisture removal from the saturated matrix is from about 40 to about 60% followed by a second stage drying wherein the moisture in the saturated matrix is reduced to about 2%, whereby said one-piece construction submicronic filter medium is formed. 2. The filter medium of claim 1 wherein said continuous matrix material is selected from the group consisting of polyester, felts, polypropylene, viscous rayon, polyolefins, and mixtures thereof having said initial micron rating. 3. The filter medium of claim 1 wherein said saturation is effected by one of depth coating, dipping, and spraying said matrix material followed by said compressing. 4. The filter medium of claim 1 wherein said drying further comprises a sterile, wet treatment wherein said matrix material is washed with fresh water and salt water over a 3 to 4 day period; followed by controlled compression treatment in a sterile environment; and final drying under mildly elevated temperature and essentially atmospheric pressure. 5. The filter medium of claim 4 wherein said first drying is conducted at a temperature of from about 160.degree. to about 250.degree. F. for a time period of from about 15 minutes to about 20 minutes for each 5 gallons of terpolymeric composition absorbed by said matrix at a constant air exchange rate. 6. The filter medium of claim 4 wherein said second drying is conducted under subatmospheric pressure condition over a time period of from about 24 to about 36 hours at a temperature of from about 100.degree. to about 160.degree. F. 7. The filter medium of claim 4 wherein said salt water wash is prepared by addition of from about 20 to about 25 pounds of research grade marine salt to about 50 gallons of sterile water which is circulated at a rate of from about 10 to about 20 gallons per minute at a temperature ranging from 150.degree. to about 190.degree. F. 8. The filter medium of claim 4 wherein said matrix is formed during said final drying stage into the desired shape. 9. The filter medium of claim 8 wherein said shape comprises a bag for fitting into a canister filtration device. 10. The filter medium of claim 1 wherein said terpolymeric polymerization mixture is prepared in an aqueous solution by mixing at a temperature range of from about 65 to about 100.degree. F. for a period of from about 30 minutes to about 60 minutes at a rate of from about 20 to about 50 rpm. 11. The filter medium of claim 10 wherein the final pH of said mixed terpolymeric solution ranges from about 10 to about 11. 12. The filter medium of claim 1 wherein the viscosity of said solution prior to application to said matrix ranges from about 22 seconds using a No. 2 Zahn Cup to about 60 seconds using a No. 4 Zahn Cup. 13. A process for high volume filtration of fluids to remove submicronic size particulate therefrom, in the substantial absence of (1) added wetting agents and solvents, (2) added electrical charge enhancers, and (3) elevated pressure differentials, comprising passing said fluid at a rate of from about 10 to about 150 gallons per minute under a pressure of gravity to not more than about 30 pounds per square inch through at least one essentially one-piece construction submicronic filter medium which comprises a continuous matrix material having an initial micron rating of from about 1 to about 5 microns which is impregnated with a hydrophilic terpolymer by step-wise addition of a low viscosity terpolymeric polymerization mixture comprising from about 10% to about 14% by weight of a polymer, which includes at least one of alkylacrylate and alkylmethacrylate, and acrylic acid; from about 17% to about 22% by weight polyethyleneimine and urea solution; from about 7% to about 10% by weight ammonia; and from about 2% to about 6% by weight epoxy resin, said polymerization mixture having a solids content of from about 16% to about 20% by weight prior to polymerization, said step-wise addition comprising saturation of said matrix material with said terpolymeric mixture followed by compressing said saturated matrix material, and repeating said saturation and compressing at least one additional time, and drying said saturated matrix material, whereby said one-piece construction submicronic filter medium is formed. 14. The method of claim 13 wherein particulate matter with particle sizes ranging from about 0.1 to about 0.9 absolute micron rating is filtered from said fluid under the pressure of from gravity to about 5 pounds per square inch.

Details for Patent 4,620,932

Applicant	Tradename	Biologic Ingredient	Dosage Form	BLA	Approval Date	Patent No.	Expiredate
Merck Sharp & Dohme Corp.	ZOSTAVAX	zoster vaccine live	For Injection	125123	05/25/2006		2003-11-04