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Scope of prior art teachings incorrect; summary judgment of obviousness reversed
February 05, 2009

In a recent decision, the Federal Circuit reversed a district court's summary judgment of obviousness. The patent related to dessicant packages. The district court held a prior art reference taught all limitations of the claims with the exception of the type of absorbent material contained in the package, and that, under KSR, it would be obvious to one of ordinary skill in the art to substitute one material for the other.

The Federal Circuit reversed, holding the prior art did not, in fact, teach all limitations with the exception of the absorbent material. Because the district court misinterpreted the scope and content of the prior art, the Federal Circuit reversed the summary judgment of obviousness, although it did not preclude the district court from granting summary judgment again on remand when reassessing the differences between the prior art and the claims.

More detail of Süd-Chemie, Inc. v. Multisorb Techs., Inc. after the jump.

Süd-Chemie owns U.S. Patent number 5,743,942 ("the '942 patent"), directed to a desiccant container which is formed of a multilayered and water-vapor-permeable packaging material. Desiccants are chemical products, such as silica gel, calcium chloride, or polyacrylonitrile, which absorb water from a local environment through chemical binding of water molecules. Desiccants are commonly used to keep products, such as pharmaceuticals or foods, dry from ambient moisture. Some desiccants function by undergoing a phase change from solid to liquid after absoribing water, and therefore need to be sealed, due to their toxic effect on consumers. Desiccant containers must therefore be permeable to water vapor while remaining impermeable to liquids.

Desiccant packages have typically been formed of two films, a microporous film and a laminate film, each coated with an adhesive and heat sealed to form a pocket about the desiccant. The '942 patent claimed a desiccant package formed without the use of adhesives on the films, attained by using films of "compatable" materials - materials that "mix on a molecular scale and will crystallize homogeneously." The films are heat sealed about their edges to form an impermeable pocket about the desiccant. The compatable films provide a better seal than obtained by the use of adhesives and noncompatable films.

Süd-Chemie sued Multisorb Technologies, Inc. ("Multisorb") for infringement of the '942 patent. After claim construction, the parties moved for summary judgment. The district court granted Multisorb's motion for summary judgment on the issue of obviousness, holding that a prior art patent to Komatsu, U.S. Patent number 4,487,791, described an oxygen absorbant material enclosed by a pocket formed by heat sealing the edges of microporous and laminate films. The district court concluded that "the Komatsu patent taught the same container as the '942 patent, with the exception of the absorbant material disposed between the layers." It further held that the substitution of desiccant for oxygen absorbing material was an obvious change, as it involved merely substituting one material (the desiccant) for another (oxygen absorbing material). Süd-Chemie appealed.

The Federal Circuit reversed. On appeal, Süd-Chemie argued Komatsu did not disclose three limitations of its independent claim 1:

  1. Use of uncoated microporous and laminated films;
  2. The water-vapor-permeabale character of the packaging materials; and
  3. use of "compatible" polymeric materials.

The Federal Circuit addressed each in turn.

First, the court held that while Komatsu did not specifically refer to the films as uncoated, the failure of Komatsu to specifically refer to the films as uncoated during the heat sealing process simply showed Komatsu anticipated the use of films uncoated with an adhesive. As a result, the district court correctly held the first disputed limitation was taught by Komatsu.

Second, the court observed that Komatsu also described the films as "waterproof." Süd-Chemie argued that this meant impermeable to both liquid water and water vapor. However, the Federal Circuit noted Komatsu described the films as permeable to "air," and that Multisorb's uncontrovered expert affidavit stated "air" invariably includes water vapor. Therefore, while Komatsu did not specifically refer to the films as "water vapor permeable," the district court was not wrong in inferring this trait, and correctly held the second disputed was taught by Komatsu.

Finally, the court turned to the third limitation requiring "compatible" polymers. Süd-Chemie contended that while Komatsu described a number of classes of materials, "polyethylene, polypropylene, and other polyolefinic materials," any two materials chosen from those groups need not necessarily be compatable. This conclusion was bolstered by the definition of "compatible" in the '942 patent, which reqwuires that "the materials mix on a molecular scale and will crystallize homogeneously." Komatsu, on the other hand, taught that the films "should have quite different softening points," such that the polymers would not be compatible, as that term is defined in the patent. As a result, although the two patents taught the same classes of polymers, the court concluded Komatsu did not teach the use of compatable films.

Süd-Chemie also argued that the district court failed to consider its evidence of secondary indicia of nonobviousness. The Federal Circuit noted that Süd-Chemie had provided evidence of unexpected results regarding the strength of the bond between the films, but did not make a judgment regarding the probative value of this evidence, and instead remanded the issue to the district court to consider.

To read the full decision in Süd-Chemie, Inc. v. Multisorb Techs., Inc., click here.

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