Sears, Roebuck & Co. v. Minnesota Mining & Mfg. Co.

• Decision Date: 01 April 1957
• Docket Number: No. 7298.,7298.
• Citation: 243 F.2d 136
• Parties: SEARS, ROEBUCK AND COMPANY and The Plymouth Rubber Company, Inc., Appellants, v. MINNESOTA MINING AND MANUFACTURING COMPANY, Appellee.
• Court: U.S. Court of Appeals — Fourth Circuit

243 F.2d 136 (1957)

SEARS, ROEBUCK AND COMPANY and The Plymouth Rubber Company, Inc., Appellants, v. MINNESOTA MINING AND MANUFACTURING COMPANY, Appellee.

No. 7298.

United States Court of Appeals Fourth Circuit.

Argued January 15, 1957.

Decided April 1, 1957.

Hector M. Holmes, Boston, Mass. (Thornton H. Brooks, Greensboro, N. C., H. L. Kirkpatrick and E. T. LeGates, Boston, Mass., on the brief), for appellants.

Lawrence C. Kingsland, St. Louis, Mo. (Welch Jordan, Greensboro, N. C., Estill E. Ezell, St. Louis, Mo., Harold J. Kinney, St. Paul, Minn., M. K. Hobbs, Platteville, Wis., and Stanley G. DeLa-Hunt, St. Paul, Minn., on the brief), for appellee.

Before PARKER, Chief Judge, and SOPER and SOBELOFF, Circuit Judges.

SOPER, Circuit Judge.

The complaint in this suit charges infringement of United States Reissue Patent No. 23,843 granted on June 29, 1954, to Ralph J. Oace, Robert Burns Snell, and Esther E. Le Page, assignors to Minnesota Mining and Manufacturing Company, the plaintiff in the District Court. The original patent No. 2,559,990 was dated July 10, 1951, and the application for reissue was filed July 9, 1952.

The invention relates to the insulation and protection of electrical conductors. For this purpose the patent specifies an adhesive insulating tape, composed of a film backing mixed with a non-volatile liquid plasticizer, a soft and viscous resinous plasticizer, and an adhesive coating united to the inner surface of the film backing. The claims of the reissued patent in issue in the pending case are claims 1, 3 and 4, which are identical with like numbered claims of the original patent, and claims 6, 7, 8 and 9, which are new in the reissued patent. Typical claims 1 and 6 are set out in full below.¹

The defendants are Sears, Roebuck and Company and Plymouth Rubber Company, Inc. Sears sold a stretchable and retractable pressure-sensitive tape under the brand name of "Homart", which was manufactured by Plymouth and is alleged to have infringed the patent. The main defenses are (1) that the accused article does not infringe the claims of the patent because there was omitted from its composition one of the ingredients specified in the claims, and (2) that claims 6 to 9, which first appeared in the reissue, are invalid if construed to omit that element from the patented structure. The District Judge held all the claims valid and infringed.

The insulating tape manufactured by the plaintiff under the patent was a great improvement over prior insulating devices and met with much commercial success. The materials which entered into the composition of the new tape were well known. Vinyl resin, plasticizers and pressure-sensitive adhesives were all old. The problem was to plasticize the vinyl resin in the backing member so that the plasticizer would not migrate into the adhesive and impair its cohesive function, and so that portions of the plasticizer would not exude from the surface of the film upon the underlying adhesive layer when the tape was wound in a roll and cause a loss of tack. The inventors overcame these difficulties and produced a strong, stretchable and retractable article that furnished effective insulation in the splicing of electric wires and cables.

This result was accomplished by securing a permanent equilibrium between the vinyl backing and the adhesive by combining the ingredients in the manner described in the following excerpt from the specification of the patent:

"In order to secure permanent equilibrium between backing and adhesive, we employ with the vinyl chloride polymer a combination of modifiers including a substantial but minor amount (not to exceed about 20 parts per 100 parts of the vinyl polymer) of a low molecular weight liquid plasticizer such as dioctyl phthalate, together with a substantially equal or somewhat greater amount of a high molecular weight resinous type plasticizer, the amount of the latter in any event being sufficient, together with the liquid plasticizer, to provide the desired degree of stretch in the final film. "Paraplex G-25" is a preferred example of a suitable resinous type plasticizer. It is sold by Resinous Products & Chemicals Corp., and is a soft, viscous alkyd resin having a specific gravity of 1.06, and an acid number of not more than 2.0; it is soluble in esters, ketones, aromatic and chlorinated hydrocarbons. Another high-molecular-weight plasticizer material which has been found useful in providing suitably stretchable and elastic vinyl polymer films is polymerized ethyl acrylate. Another example is polymerized vinyl butyl ether.

"While resinous or high molecular weight modifiers such as "Paraplex G-25" are themselves capable of producing the desired degree of strength, stretch and elasticity in vinyl chloride polymer films, and furthermore are generally classed as "non-migrating" or "permanent" type modifiers or plasticizers, it is surprisingly found that these materials do not provide for permanent equilibrium of adhesive and backing as herein defined. Instead, it has been shown that pressure-sensitive adhesives in prolonged contact with highly stretchable and elastic films consisting solely of vinyl polymer and resinous modifier lose a great deal, if not all, of their initial tackiness or pressure-sensitivity. When tape made in this way is unwound from roll form, after a moderate period of storage, and applied to a splice, it does not adhere either to the electrical conductor or to its own backing, and hence is of no value as an insulating and protective coating."

Based on this disclosure, typical claim 1 of the patent declares that the patented tape is comprised of an elastic film backing formed of a homogeneous mixture consisting of a blend of (1) a major proportion of vinyl chloride, (2) a substantially non-volatile liquid phytalyl ester plasticizer, (3) a soft and viscous low-acid-number alkyd plasticizer resin in amount at least equal to the amount of the liquid plasticizer, and (4) a pressure-sensitive rubber resin type adhesive coating united to the inner surface of the film backing.

Testimony bearing on the investigation and experiments which lead to the invention confirms the foregoing statement in the specification as to the ingredients of the product listed in claim 1. In 1938 or 1939, the plaintiff commenced its efforts to make a suitable adhesive plastic tape, using commercial vinyl (VYNS) with 25% to 40% of liquid tricresyl phosphate plasticizer, and a standard pressure-sensitive adhesive; but the experiment was unsuccessful, because the plasticizer migrated and made the adhesive very soft and pasty. In 1942 or 1943, Rohm and Haas, a widely known chemical company of Philadelphia, produced a new type of high-molecular-weight resinous plasticizer known as "Paraplex G-25", which could be combined satisfactorily with vinyl without causing migration. Early in 1944 plaintiff's research workers, to whom the patent in suit was subsequently issued, began to experiment with G-25 in combination with standard vinyl and standard adhesives from stock in an effort to make a satisfactory insulating tape. They found that G-25 did not migrate to the adhesive or soften it as the liquid plasticizer had done, but it did cause a loss of tack in the adhesive. Thus finding that neither the liquid nor resinous plasticizer when used alone gave satisfactory results, they tried a mixture of the two using a combination of dioctyl phthalate (DOP), a low-molecular-weight plasticizer, and G-25, a high-molecular-weight resinous plasticizer. This combination solved the difficulty and subsequently lead to the production and sale of the plaintiff's commercial article in 1945 and to the application for the original patent in 1946. The product speedily came into wide use and sales advanced from a little over $8000 during the year 1945 to more than $8,000,000 in 1953.²

The defendant, Plymouth Rubber Company, entered the field subsequently and began to experiment with adhesive vinyl plastic tape in 1948. It also had migration difficulties when it used the standard liquid plasticizer DOP and also found that G-25 was hard to disperse. Thereupon it experimented with G-40 as the sole plasticizer and found that it gave satisfactory results. Using it as the sole plasticizer the defendant produced a commercial article, which it put on the market in 1950 before the original patent was issued on July 10, 1951. The plasticizer G-40 was also manufactured by Rohm and Haas in 1945. It is a high-molecular-weight resinous plasticizer similar to G-25 but less expensive. It had also been used experimentally as the sole plasticizer by plaintiff's researchers, who reported that it was substantially equivalent to G-25 and caused a loss of tack but less loss than G-25. In 1946 or 1947, the plaintiff substituted G-40 for G-25 in the mixture with DOP in its commercial operations and this mixture became its standard commercial product.

In 1954, Plymouth found that by using a certain wax G-25 could be used successfully with vinyl as the sole plasticizer and prior to the institution of the pending suit made and sold such a product to the United States and, to some extent, to the general trade. In the complaint filed in the pending case plaintiff charges infringment by the defendant by the use of both G-25 and G-40 as the sole plasticizer.

The facts so far related give substance to the main defense to the suit that the defendants did not infringe the patent because they omit from their production one element or ingredient, to wit, the liquid plasticizer, which is specified in the claims of the patent. It is well established that there is no infringement when this occurs even though the same result is obtained because the accused article is not covered by the claims of the patent. See Vance v. Campbell, 1 Black 427, 429, 66 U.S. 427, 17 L.Ed. 168; Acme Steel Co. v. Eastern Venetian Blind Co., 4 Cir., 227 F.2d 914; Anthony v. Sherman, 4 Cir., 159 F.2d 995; Kaumagraph...