Cantwell v. 3M Co

I. Executive Summary and Procedural Information

• Parties & Counsel:
  • Plaintiff: Jay S. Cantwell (Missouri)
  • Defendant: 3M Company and 3M Innovative Properties Company (Delaware)
  • Plaintiff’s Counsel: Shoemaker & Shoemaker, P.L.L.C.
• Case Identification: 0:19-cv-02484, D. Minn., 09/09/2019
• Venue Allegations: Venue is alleged based on Defendants having a principal place of business in Minnesota, regularly transacting business there, and committing alleged acts of infringement within the district.
• Core Dispute: Plaintiff alleges that Defendant’s Soft Edge Foam Masking Tape products infringe a patent related to a method and apparatus for creating a smooth, feathered paint edge in automotive and other spray-painting applications.
• Technical Context: The technology addresses the need in vehicle repair and manufacturing to blend new paint into existing paint without creating a hard, visible line, a process known in the industry as creating a "soft edge" or "feathering effect."
• Key Procedural History: The complaint alleges that Defendant 3M was made aware of the Plaintiff’s technological development through its distributors prior to launching the accused products, which may form the basis for the willfulness allegation.

Case Timeline

II. Technology and Patent(s)-in-Suit Analysis

U.S. Patent No. 5,786,028 - "Masking Tape and Method"

• Patent Identification: U.S. Patent No. 5,786,028, "Masking Tape and Method", issued July 28, 1998.

The Invention Explained

• Problem Addressed: The patent's background describes the shortcomings of prior art masking tapes used in painting. Basic tapes create a "ragged edge" when removed, while existing "feathering" tapes were often not flexible enough for curved automotive body panels or could not withstand the high temperatures of production-line drying ovens. (’028 Patent, col. 1:21-43, col. 2:1-22).
• The Patented Solution: The invention is a method using a flexible tape with a specific geometric cross-section. The tape has an adhesive-coated bottom surface and a "lateral edge" that is "sloped upwardly and outwardly" to overhang the point where the tape meets the workpiece (the "vertex"). (’028 Patent, col. 2:40-51). This sloped structure creates a "shadow zone," physically blocking paint spray from reaching the demarcation line directly, which results in a gradual, feathered paint edge rather than a sharp one. (’028 Patent, col. 3:45-54; Fig. 2).
• Technical Importance: The claimed invention sought to provide a tape that could create a high-quality feathered paint edge while also being flexible enough for complex curves and durable enough for automated, high-temperature industrial painting processes. (’028 Patent, col. 1:11-16).

Key Claims at a Glance

• The complaint asserts independent Claim 1. (Compl. ¶24).
• Essential elements of Claim 1 (a method claim) include:
  • Providing a flexible tape with a specific body structure, including a bottom surface with adhesive and at least one lateral edge.
  • The bottom surface forms a "vertex" with the workpiece.
  • The lateral edge has a leading portion that is "sloped upwardly and outwardly from the bottom surface and overhanging the vertex."
  • Spraying paint at an angle such that the sloped lateral edge creates a "shadow zone."
  • Terminating the spray before paint flows into the shadow zone and contacts the lateral edge.
• The complaint does not explicitly reserve the right to assert dependent claims, though this is standard practice.

III. The Accused Instrumentality

Product Identification

• The "3M™ Soft Edge Foam Masking Tape" product line is accused of infringement. (Compl. ¶19).

Functionality and Market Context

• The complaint alleges the accused product is a masking tape used to create a "soft edge" or "feathering effect" when painting. (Compl. ¶18). It is described as being of "tubular construction" and providing a "shadow zone when adhered onto a work piece." (Compl. ¶20). The complaint includes a diagram illustrating the accused 3M product as a cylindrical or tubular piece of foam with an adhesive strip along one side. (Compl. ¶20, p. 6). This product is marketed for the same purpose as the patented invention—to mask door jambs and other vehicle apertures to create a smooth paint transition.

IV. Analysis of Infringement Allegations

’028 Patent Infringement Allegations

Identified Points of Contention

• Scope Questions: The primary point of contention will likely be the structural differences between the claimed invention and the accused product. The complaint's own diagram depicts the 3M product as having a "tubular construction," which appears to be a round foam cylinder. (Compl. ¶20, p. 6). In contrast, the ’028 patent repeatedly illustrates a solid body with a distinct, planar "sloped" edge and a sharp "vertex." (Compl. ¶16; ’028 Patent, Figs. 2-5). This raises the question of whether the curved surface of a foam tube can be construed as a "lateral edge sloped upwardly and outwardly" that "overhangs" a "vertex" as those terms are used in the patent.
• Technical Questions: A key evidentiary question will be how the accused tubular tape actually functions. The complaint asserts that it creates a "shadow zone" (Compl. ¶20), but it does not explain the mechanism. The court will need to determine if the rounded surface of the foam tube creates a "shadow zone" in the specific manner required by the claims—by "shadowing the vertex from the spray." (’028 Patent, col. 5:42-44).

V. Key Claim Terms for Construction

• The Term: "lateral edge... sloped upwardly and outwardly from the bottom surface and overhanging the vertex"
• Context and Importance: This phrase captures the core geometry of the claimed tape, which is responsible for creating the "shadow zone." The outcome of the infringement analysis will heavily depend on whether the "tubular construction" of the accused 3M product (Compl. ¶20) falls within the scope of this language. Practitioners may focus on this term because the visual and descriptive mismatch between the patent's solid, angular embodiments and the accused product's cylindrical shape is the most apparent difference.
• Intrinsic Evidence for Interpretation:
  • Evidence for a Broader Interpretation: The patent states that "other shapes in cross-section are possible and for some applications may be preferred, e.g. trapezoidal, etc." (’028 Patent, col. 5:3-5). Plaintiff may argue that "tubular" is another such possible shape and that the claim terms should be interpreted functionally to cover any shape that overhangs the workpiece to create a shadow zone.
  • Evidence for a Narrower Interpretation: All figures in the patent (Figs. 2, 3, 4, 5) depict a solid body with a distinctly flat, angled surface for the "sloped" edge, not a curved one. The specification describes the creation of this edge by cutting a "sheet of rubber... into strips," which suggests a solid, non-tubular product. (’028 Patent, col. 4:59-63). The use of the term "vertex"—implying an angle or corner—may further support a narrower construction that excludes a continuously curved, tubular surface. (’028 Patent, col. 3:49).

VI. Other Allegations

• Indirect Infringement: The complaint alleges that Defendants induce infringement by selling the tape to third parties with knowledge that it has "no purpose other than to be used to carry out infringement." (Compl. ¶23). It also alleges contributory infringement based on selling the tape to be used with spray heads acquired from others. (Compl. ¶22).
• Willful Infringement: Willfulness is alleged based on Defendants' purported pre-suit knowledge. The complaint alleges that "3M was made aware of Plaintiff's development through at least 3M distributors" and "appropriated that concept." (Compl. ¶28). It also alleges Defendants were "at all relevant times aware of the '028 Patent and knowingly... disregarded and infringed the patent." (Compl. ¶31).

VII. Analyst’s Conclusion: Key Questions for the Case

The resolution of this case will likely depend on the answers to two central questions:

1. A core issue will be one of definitional scope: Can the claim terms "lateral edge sloped upwardly and outwardly" and "vertex," which are described and depicted in the patent as features of a solid, angular body, be construed to read on the curved, "tubular construction" of the accused foam tape?
2. A key evidentiary question will be one of infringement under the doctrine of equivalents: If the accused product is found not to literally infringe due to its different structure, does its tubular shape perform substantially the same function (creating a feathered edge) in substantially the same way (by creating a "shadow zone" via an overhanging surface) to achieve substantially the same result, such that it could be found to infringe under the doctrine of equivalents?