USM Corp. v. Detroit Plastic Molding Co.
| Decision Date | 19 April 1982 |
| Docket Number | Civ. A. No. 76-72536. |
| Citation | 536 F. Supp. 902 |
| Parties | USM CORPORATION, Plaintiff, v. DETROIT PLASTIC MOLDING COMPANY, Defendant. |
| Court | U.S. District Court — Western District of Michigan |
COPYRIGHT MATERIAL OMITTED
Clunet Lewis, Detroit, Mich., Gerald D. Hosier, Raymond P. Niro, Thomas G. Scavone, Chicago, Ill., for plaintiff.
Chester L. Davis, Jr., Detroit, Mich., Ernie L. Brooks, Southfield, Mich., for defendant.
On December 4, 1973, Plaintiff, USM Corporation (USM), as assignee of inventors, R. E. Annis, Jr. (Annis) and W. T. Kyritsis (Kyritsis) was granted United States Patent 3,776,989 (989 Patent). This Patent is entitled, "Method for Injection Molding Articles of Foam Material Involving Autogenous Flow." The abstract thereof provides a concise summary of its disclosure:
"A process of molding articles of foam material comprising forming a mixture of organic polymeric resin material and a blowing agent in a chamber at a temperature below the foaming temperature of the resin-blowing agent system and forcing the mixture through a restriction for resisting the flow of the material to impart heat to the material, the heat imparted being of a magnitude sufficient to raise the temperature of the mixture to the foaming temperature, and discharging the mixture, at its foaming temperature, into a mold cavity."
On April 2, 1974, USM, as assignee of inventors, Kyritsis and R. C. Simmonds, Jr. (Simmonds), was granted United States Patent 3,801,686 (686 Patent). This Patent is entitled, "Method of Injection Molding Articles of Foam Material." The abstract thereof states:
On December 9, 1976, USM filed a Complaint, which alleged infringement of these two Patents by Defendant, Detroit Plastic Molding Company (DPM). In its answer, DPM denied infringement. It also filed a Counterclaim, which sought a declaratory judgment that the Patents-in-suit are invalid.
This matter was tried by the Court without a jury over thirty-four trial days. USM called twelve witnesses to testify and DPM called four witnesses, including two persons who had already testified for USM. The Court found the following witnesses to be most helpful in the resolution of the issues:
The Court also received numerous documents and physical exhibits into evidence.2
In its deliberations after the trial, the Court had the benefit of the parties' Post-Trial Briefs, Proposed Findings of Fact and Conclusions of Law, and Reply Briefs.
This Opinion constitutes the Court's Findings of Fact and Conclusions of Law, as required by Rule 52, Federal Rules of Civil Procedure.
(1) As is apparent from the abstracts of the above-quoted Patents-in-suit, these Patents involve a foam plastic injection molding process. That process is grounded in the conventional (non-foam) plastic injection molding process. Both processes utilize an injection machine consisting of a hopper, a barrel, a screw, a shut-off valve, a nozzle and a mold. In both processes, plastic pellets are loaded into the hopper directly into one end of the barrel,3 which contains a screw. This screw serves three purposes. Its mechanical action not only heats the pellets to melt them, but also moves the plastic from the hopper end of the barrel to the nozzle end. Finally, the screw operates to ram the melted plastic through the opened shut-off valve, through the nozzle and into the mold. Therein the plastic cools, solidifies, and takes the shape of the mold. After the plastic solidifies, the mold is opened, and the molded part is removed. Thereafter, the mold is closed, and the machine cycles once again by injecting another shot of melted plastic into the mold.
It has been well known for a long time in the conventional injection molding art that it is crucial to control the temperature of the plastic as it enters the mold. If the plastic is too hot, the finished parts will exhibit splay and blisters. If the plastic is too cold, the finished parts will exhibit sink marks and lack of fill. Thus, the concept of a "temperature window" in the conventional injection molding process is well known.
The methods of controlling the temperature of the plastic upon injection into the mold are also well known. There are several process parameters that can be adjusted to control that temperature, including the temperature of the barrel (which may be controlled by heating or cooling), the residence time of the plastic in the barrel, and the injection rate.4 Those who practice this art have been fully knowledgeable in the experimental procedures that are necessary with respect to these process parameters, in order to set up and operate the conventional injection process to achieve acceptable part quality.
(2) The difficulty with the conventional process arises out of the fact that as plastic cools, it contracts and sinks develop, most notably in the thicker sections of the part.
Thus, beginning about 1960, there was substantial research into the use of foam in the injection molding process. The concept is simple enough. By adding to the plastic in the barrel a chemical called a blowing agent, which decomposes into a gas when sufficiently heated, the plastic would be "foamed" after injection into the mold and the sink problem would be solved. Especially attractive to industry is the "sandwich constructed" part, the inner portion of which has a cellular structure, and the outer skin portion of which is solid. This solid outer portion allows the surface detail of the mold to be precisely reproduced. Such a part is also lighter and uses less plastic than a similar non-foamed plastic part.
(3) Several processes were developed in an effort to produce parts with such characteristics. Union Carbide developed a process in which the mold is only partially filled (called a low pressure process), so that the foaming process itself fills out the mold. However, this process resulted in little, if any, solid skin because the entire plastic was foamed. The resulting surface quality was deemed unacceptable by some.
Dow Chemical Company (Dow) promoted a process,5 in which the mixture of the plastic and the blowing agent is heated to the temperature where it would be expected to foam in the barrel. However, pressure is applied throughout the injection machine and the mold to restrain foaming until after injection. The entire mold is filled, and the expansion of the decomposing blowing agent is accommodated by expanding the mold. This process is called a high pressure process. Dow attempted to promote this process; however, in 1977, after twenty years, it abandoned the effort.
In the USM foam process, which was disclosed in the Patents-in-suit, the mixture of plastic and blowing agent is not heated in the barrel to the temperature where the blowing agent decomposes. (This temperature is called the decomposition temperature, or the foaming temperature.) Rather, sufficient heat is added during injection by means of shear friction, so that foaming commences when the mixture is in the mold. While the mixture in the mold is still fluid, the mold is expanded to allow the gas, which was generated by the decomposing blowing agent, to expand. Thus, a foamed inner portion is created. However, through the use of cooled mold walls, foaming is arrested in the portion of the mixture adjacent to the walls, so that it has a solid skin outer surface when the part cools.6
The evidence shows that the USM foam process has achieved significant commercial acceptance and success, although it has not been as successful as USM had hoped or projected.
(4) DPM manufactures and supplies molded plastic parts to industry, and uses many processes, including both the conventional plastic and the foam plastic injection molding processes. From 1972 through 1975, it obtained substantial information from both Dow and USM concerning their respective foam processes. In 1975, DPM contracted with the Chevrolet Division of the General Motors Corporation (General Motors) to produce and supply glove box doors of foam construction. The present controversy arises from that contract. USM contends that DPM, in fulfilling that contract, uses and infringes the processes that have been described in the Patents-in-suit. On the other hand, DPM contends that it uses the Dow process.
Specifically, USM contends...
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USM Corporation v. Detroit Plastic Molding Company
...720 F.2d 680 USM Corp. v. Detroit Plastic Molding Co. 82-1339, 82-1357 UNITED STATES COURT OF APPEALS Sixth Circuit 9/22/83 E.D.Mich., 536 F.Supp. 902 ...