PTAB

IPR2019-00336

Werner Co v. Louisville Ladder Inc

Title: Multi-Material Cover for a Ladder Rail End
Brief Description: The ’731 patent discloses a protective cover for the end of a ladder rail, comprising a rigid shell made of one material and a slip-resistant tread made of a different material, where the tread is engaged with the shell by at least one bond.

Prior Art Relied Upon: The Louisville Catalogs (three publications from 1999-2001).
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that the Louisville Catalogs, which advertised a "FULL METAL BOOT" for the Rhino 375 ladder, taught every limitation of independent claim 8. The boot was described as a cover with a metal "shell" and a "thick rubber" "tread," satisfying the different material requirements. Petitioner asserted that photographs in the catalogs showed the shell had an "entirely open face" exposing the ladder rail and was attached to the rubber tread using rivets. These rivets, Petitioner contended, constituted the claimed "at least one bond" under its proposed broad construction of that term. The catalogs also allegedly disclosed the additional features of dependent claims 9 and 11 (slanted base) and independent claim 10 (rail flange retainers).

Prior Art Relied Upon: Plotner (Patent 5,636,706) and the Louisville Catalogs.
Core Argument for this Ground:
- Prior Art Mapping: Petitioner argued that Plotner taught a ladder rail cover with nearly all the claimed structural features, including a shell with a first wall, side walls, an entirely open face, a slanted base, and a perimeter wall. However, Plotner did not explicitly teach that the tread must be formed of a material different from the shell. The Louisville Catalogs' disclosure of a metal shell with a separate rubber tread on its "FULL METAL BOOT" was argued to supply this missing element.
- Motivation to Combine: A POSITA would combine Plotner’s structural design with the different material construction from the Louisville Catalogs to achieve improved and predictable performance. It was well-known that the shell required a strong, impact-resistant material (like the plastic suggested by Plotner or the metal in the Catalogs) while the tread required a high-friction, slip-resistant material (like the rubber in the Catalogs).
- Expectation of Success: Combining known materials for their well-understood and distinct properties—durability for a shell and friction for a tread—was a routine design choice that would have yielded a predictable and successful ladder foot.

Prior Art Relied Upon: Plotner, the Louisville Catalogs, and the Werner Brochure (a 2000 publication).
Core Argument for this Ground:
- This ground presented an alternative argument, assuming a narrower construction of "bond" that excludes mechanical fasteners. Petitioner argued that Plotner and the Louisville Catalogs taught all limitations except for such a non-mechanical bond.
- Prior Art Mapping: The Werner Brochure was introduced to teach the missing non-mechanical bond. It disclosed a ladder foot with black studs extending from the tread through holes in the shell. Petitioner argued a POSITA would have understood these studs to be integral parts of an injection-molded tread, forming an interlocking bond without separate fasteners.
- Motivation to Combine: A POSITA would substitute the interlocking stud bond from the Werner Brochure for the riveted bond of the Louisville Catalogs to reduce manufacturing costs and simplify assembly. This was presented as a simple substitution of one known bonding method for another to achieve a known economic benefit.

Prior Art Relied Upon: Plotner, the Louisville Catalogs, the Werner Brochure, and the Modern Plastics Handbook (a 2000 publication).
Core Argument for this Ground:
- This ground built upon the combination in Ground 3 to specifically address dependent claims 19 and 20, which required the shell to comprise a "copolymer" and the tread to comprise a "thermoplastic elastomer," respectively.
- Prior Art Mapping: The Modern Plastics Handbook was presented as a reference a POSITA would naturally consult for specific material selection to implement the plastic shell and rubber-like tread taught by the primary references.
- Motivation to Combine: The Handbook taught that copolymers (e.g., polypropylene-polyethylene) provide excellent impact strength and low-temperature durability, making them an obvious choice for a ladder shell. It also taught that thermoplastic elastomers provide rubber-like slip resistance while being suitable for cost-effective manufacturing processes like injection molding, making them an obvious choice for the tread. A POSITA would have been motivated to select these specific materials to optimize the ladder cover's performance, durability, and manufacturability.

Petitioner argued that the phrase "at least one bond" in the challenged claims should be construed broadly to encompass any type of connection, including mechanical fasteners like rivets.
The basis for this position was that the patent specification explicitly lists mechanical fasteners as an example of a suitable bond. Further, Petitioner contrasted this broad language with the narrower phrasing in unchallenged claim 1, which recites a "bond independent of mechanical fasteners," arguing this shows the patentee knew how to exclude mechanical fasteners when intended. This broad construction was foundational to Petitioner's anticipation argument in Ground 1.

Petitioner requested institution of an inter partes review and cancellation of claims 8-16 and 19-20 of the ’731 patent as unpatentable.