Pall Corp. v. Micron Separations, Inc.

792 F. Supp. 1298

PALL CORPORATION, Plaintiff, v. MICRON SEPARATIONS, INC., Defendant.

Civ. A. No. 86-1427-Y.

United States District Court, D. Massachusetts.

April 24, 1992.

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George P. Field, Boston, Mass., Paul J. Korniczky, C. Frederick Leydig, H. Michael Hartmann, Leydig, Voit & Mayer, Chicago, Ill., for plaintiff.

Nicholas Halpern, Ropes & Gray, Boston, Mass., Richard A. Huettner, Albin J. Nelson, Kenyon & Kenyon, New York City, for defendant.

MEMORANDUM OF DECISION¹

YOUNG, District Judge.

This case involves United States Patent 4,340,479 (the "Pall patent") covering a process for preparing hydrophilic polyamide membrane filtered media and product, which issued on July 20, 1982 to the plaintiff Pall Corporation ("Pall"). Pall is a New York corporation having a principal place of business in Glen Cove, New York, and offices on Route 25A in Roslyn, New York. Pall was founded in the late 1940's by Dr. David B. Pall of Roslyn Estates, New York. Dr. Pall is designated as the inventor of the patent-in-suit.

The action is brought against the defendant Micron Separations, Inc. ("MSI"), a Massachusetts corporation having a principal place of business in Westborough, Massachusetts. MSI was formed in 1981 when certain employees of a filtration company known as Millipore, specifically James S. Johnson and John M. Greenwood, left that company and, along with Edward J. Ackley, decided to start their own company and enter into competition with Pall, Millipore, and others in the microporous filtration industry.

The complaint in this action was filed on May 7, 1986. It seeks a judgment that MSI has willfully infringed the Pall patent. The complaint also seeks damages for past infringement and an injunction against future infringement.

I. Prior Art

A. The general setting.

At this juncture it's helpful to put some matters in perspective. Polymeric membranes are thin, sheet like materials with very small interconnected pores. The pores usually range in size from about one-tenth of a micron to ten microns. The membranes are made from a chemical material that has many thousands of repeating units, a polymer. There are many such materials, many methods for making them into membranes, and many uses for such membranes.

Polymeric membranes, in the strictest sense of the word, may be fibrous or non-fibrous. Usually, however, when the term polymeric membrane is employed, the non-fibrous type is meant. Non-fibrous membranes are usually made directly from a solution or melt of the polymer. Fibrous polymeric membranes are made by first converting the polymer into fibers, and then making a thin web from those fibers. Potassium titanate is a good example of a fibrous polymeric membrane.

Prior to the development of the Pall nylon membrane, fibrous filter media, made, for example, from potassium titanate or asbestos, were commonly employed as filtration medium. At the present time, the two most commonly used microfiltration membranes are Pall's nylon membrane and Millipore's PVDF membrane, both made from non-fibrous polymers. They are employed mainly in the filtration of liquids to remove very small particles, including bacteria, a process known as microfiltration.

Typical filtration applications include use by pharmaceutical companies to assure that the drugs they make are free of bacteria contamination, use by electronic companies to purify water for chip manufacture, and use by hospitals to assure that the fluids administered to patients are free from bacteria and other contaminants. Typical biotechnological applications include use in diagnostics to detect the presence of antibodies and the so-called transfer membranes for identification of genetic characteristics.

Depending upon their use, polymeric membranes may have a skin on them, or they may be without a skin. Certain processes, reverse osmosis, for example, require the presence of a continuous skin, while in other processes microfiltration, for example, the complete absence of any skin is necessary.

Microfiltration is one of the most common applications for polymeric membranes at this time. It is, however, by no means the only application. Membranes are also used in reverse osmosis, electrophoresis, dialysis, electrodialysis, gas separation, and immobilization and transfer of substances. Microfiltration is the regime with pores between about one-tenth of a micron and 10 microns. The most important pore size is .2 micron because this is the pore size that gives the highest flow rates and throughputs consistent with the retention of the approximate .3 micron Pseudomonas diminutia bacteria which is the criterion for a pore size rating equivalent to sterilization. Today commercially acceptable microfiltration membranes are skinless and macrovoid-free and have a narrow pore size distribution which maximizes their efficiency at removing bacteria, and other particulate matter of equivalent size, from fluids.

Other uses for microfiltration membranes are now found more and more in the biotechnology area. Polymeric membranes are there employed, for example, to hold certain substances such as antibodies, antigens or other proteins while blood or other body fluids are passed through the membrane.

Over the years, many different polymers have been investigated as possible membrane media in a number of different applications. By the late 1970's, the list included the following, without any attempt to be exhaustive:

Polymer                                             Application
Cellulose acetate and nitrate including mixtures    Electrophoresis
                                                    Microfiltration
                                                    Ultrafiltration
                                                    Reverse Osmosis
                                                    Gas Separation
Cellulose triacetate                                Microfiltration
                                                    Ultrafiltration

Polymer                                              Application
                                                     Reverse Osmosis
Cellulose acetate/triacetate blends                  Reverse Osmosis
Polyacrylonitrile                                    Ultrafiltration
Polyacrylonitrile-polyvinyl-chloride copolymer       Microfiltration
Polyamide (incl. various nylons)                     Microfiltration
                                                     Ultrafiltration
                                                     Reverse Osmosis
                                                     Immobilizing
                                                     Medium
Polyaryl Sulfone                                     Ultrafiltration
Polycarbonate                                        Microfiltration
                                                     Reverse Osmosis
                                                     Electrophoresis
Polyester                                            Microfiltration
Polyether Sulfone                                    Ultrafiltration
Polyimide                                            Ultrafiltration
                                                     Reverse Osmosis
                                                     Microfiltration
Polypropylene
Polysulfone                                          Microfiltration
                                                     Ultrafiltration
Polytetrafluoroethylene (PTFE)                       Microfiltration
Polyvinylchloride                                    Microfiltration
Polyvinylidenefluoride (PVFD)                        Microfiltration
                                                     Ultrafiltration
Dr. Kesting Direct Testimony at 7

By 1978, many methods had been investigated for making the polymers mentioned above, and many other polymers not here mentioned in porous membranes. They included: casting membranes from a melt of the polymer; casting from a polymer solution into an evaporative atmosphere; casting from a polymer solution into a nonsolvent liquid; stretching semi-crystalline films; thermal gelling by decreasing the temperature of the polymer solution; inducing porosity by irradiation of polyester and/or polycarbonate films; binding the polymer into a thin sheet structure by sintering.

In 1978, the leading manufacturers of microfiltration media were Pall with its fibrous potassium titanate product, and Millipore with its membrane made of a mixture of cellulose nitrate and cellulose acetate. Several other membrane products were on the market, but none had any significant market share. Most, if not all, of the polymeric non-fibrous membranes were made by a process that involved casting from a solution followed by evaporation or quenching in a liquid.

Pre-1978 filter media, fibrous and non-fibrous, suffered from one or another of the following deficiencies: brittleness, unless highly plasticized they could not be pleated and incorporated into a cartridge; marginal thermal stability, the membrane shrank excessively while being sterilized with steam; high extractables, the surfactants employed to render the membranes hydrophilic so that they could be used with acqueous fluids and the plasticizers required to permit the membranes to be made into useful products leached out of the membrane while in use; poor solvent resistance, the membranes softened or dissolved when used in certain solvents; limited flowrate, the amount of liquid per unit time capable of flowing across the membranes was limited; limited throughput, the membranes clogged easily and thus had to be exchanged frequently; limited sterilizing ability, the membranes could not consistently produce bacteria-free fluids; poor dimensional stability, the membranes swelled in water; danger of fiber sloughing into the permeate, unless specially treated fibrous materials tend to slough off fibers into the permeate.

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