Ridge Corp. v. Kirk NationaLease — Federal Circuit Reverses Preliminary Injunction, Finding Substantial Non-Infringement Questions on Three Patent Claim Limitations

Background

Cold Chain, LLC owns U.S. Patent No. 9,151,084 (the “‘084 patent”) covering a single-panel insulated overhead door designed for roll-up use in cold-storage trucks. The key design feature is a panel made from a thermoplastic membrane bonded directly to a layer of foam insulating material — with the foam forming one of the outermost surfaces. Ridge Corporation became the exclusive licensee of the patent in February 2023.

Ridge and Cold Chain sued Kirk NationaLease Co., Truck & Trailer Parts Solutions, Inc. (TTPS), and Altum LLC (collectively, “the KNL defendants”), alleging that their competing door infringed the ‘084 patent. The accused product is a “sandwich” panel door: a middle foam layer flanked by two thermoplastic membranes on either side. To allow the rigid panel to navigate curved door tracks, TTPS routes horizontal grooves — called compression gaps — into the foam layer after purchasing the panel from Altum. The district court (S.D. Ohio) granted a preliminary injunction barring the KNL defendants from making and selling the accused door. This was the second preliminary injunction in the case; an earlier injunction had been vacated by the Federal Circuit in 2024 because Ridge lacked standing as an exclusive licensee without all substantial rights. After Cold Chain joined the case, the district court granted a renewed injunction.

The KNL defendants appealed again, arguing that the district court improperly construed several claim terms and that Ridge had not shown irreparable harm.

The Court’s Holding

The Federal Circuit reversed the preliminary injunction in a precedential opinion authored by Judge Mayer. The court found that the KNL defendants had raised substantial questions of non-infringement under three separate claim limitations of the ‘084 patent — any one of which would have been sufficient to defeat the injunction.

1. “Flexible along the entire length.” Claim 1 requires a panel that is “flexible along the entire length of the panel so as to be capable of approximating the curvature of curved tracks.” The KNL defendants’ sandwich panel is rigid and inflexible as manufactured; TTPS adds compression gaps to enable track traversal. But the sections of the panel without those grooves remain rigid. The court held that the claim’s plain text imposes two independent requirements — that the panel be flexible throughout its entire length, and that this flexibility enables it to follow curved tracks. Ridge’s interpretation — that only the end result of track-traversal matters — would read the “flexible along the entire length” requirement entirely out of the claim. The prosecution history confirmed this: during prosecution, Cold Chain stated that “the entire panel is made from flexible material,” distinguishing its invention from designs with alternating rigid and flexible sections.

2. “Foam insulating material forming the second outermost surface.” Claim 1 requires that foam insulating material form the door’s second outermost surface. In the accused door’s sandwich construction, the outermost surfaces on both sides are thermoplastic membranes — not foam. The court found no ambiguity: “outermost” means farthest out, and the foam is the middle layer (as the defendants aptly described it, “the ice cream in an ice cream sandwich”). The prosecution history reinforced this reading: Cold Chain had distinguished its claims from a prior-art sandwich-construction door (the Rauenbusch patent) on exactly this basis. The court rejected Ridge’s argument that dependent claim 9 (which permits “an additional membrane”) implied that a sandwich structure falls within claim 1, reaffirming that a dependent claim cannot expand the clear scope of an independent claim.

3. “Insulated overhead door” requires cold-storage suitability. The court also found a substantial question over whether the accused door qualifies as an “insulated overhead door” at all. The specification repeatedly connects “insulated” doors to cold-storage transport of frozen or refrigerated goods and emphasizes advantages like higher R-value and reduced heat intrusion. Industry expert testimony confirmed that the trade meaning of “insulated roll-up door” refers to doors for refrigerated or frozen goods transport, not dry-freight applications. The court held the term is best read to require suitability for cold-storage use — and the accused door’s thin foam layer and heat-sink groove geometry raised substantial doubts about that.

Irreparable harm. Independently, the court found that Ridge’s irreparable harm showing was “speculative at best.” Ridge alleged price erosion — that competition from the KNL defendants had forced it to cut prices. But Ridge presented no evidence of a causal nexus between the defendants’ sales and its own pricing decisions. The court noted that Ridge had not sold any single-panel roll-up doors before the first injunction in 2023 and that after that injunction Ridge “had the field to itself for a full year” — undercutting any claim that KNL sales were driving prices down.

Key Takeaways

• Prosecution history cuts both ways: Cold Chain’s arguments distinguishing sandwich-construction prior art during prosecution now limit how broadly it can read its own claims against a sandwich-construction competitor.
• A preliminary injunction fails if the defendant raises a substantial question of non-infringement under any material claim limitation — the court need not find the patent invalid or definitively non-infringed.
• Price erosion as irreparable harm requires more than an assertion: patent owners must produce evidence of a causal nexus connecting the accused product’s sales to their own pricing decisions.
• The court left open whether unasserted dependent claim 9 (covering a door with an additional membrane) might provide an alternative path for the patentee on remand.
• Non-patent claims (tortious interference; false marking) cannot independently sustain a preliminary injunction when the underlying conduct shows no substantial risk of recurrence.

Why It Matters

Preliminary injunctions in patent cases remain hard to win, and this ruling reinforces the Federal Circuit’s demanding standard. For manufacturers competing with patented products, this decision shows that carefully mapping accused features to claim limitations — and mining the patentee’s own prosecution history — can block an injunction before trial ever begins. Even if a product ultimately turns out to infringe, raising substantial questions at the preliminary stage is enough to keep selling while the case proceeds.

For patent owners, the case is a reminder that arguments made during prosecution to distinguish prior art do more than secure a patent — they narrow how that patent can be enforced. Cold Chain’s choice to distinguish sandwich-construction doors during prosecution helped it get the patent issued, but now constrains its ability to reach exactly that design in a competitor’s product.