Billerud Aktiebolag Publ v. WestRock MWV LLC

1. Case Identification

• Case #: IPR2023-01206
• Patent #: 11,293,142
• Filed: July 14, 2023
• Petitioner(s): Billerud Aktiebolag (publ)
• Patent Owner(s): Westrock MWV, LLC.
• Challenged Claims: 1, 2, and 4-24

2. Patent Overview

• Title: Smooth and Low Density Paperboard Structures and Methods for Manufacturing the Same
• Brief Description: The ’142 patent discloses methods for manufacturing smooth, low-density paperboard. The process involves passing a paperboard substrate through a hot-hard calender with a thermo-roller heated to at least 250°F prior to applying a basecoat and topcoat.

3. Grounds for Unpatentability

Ground 1: Obviousness over Fugitt and Papermaking - Claims 1, 2, and 4-24 are obvious over Fugitt in view of Papermaking.

• Prior Art Relied Upon: Fugitt (Application # 2009/0236062) and Papermaking (a 2009 book, Papermaking Science and Technology Book 10: Papermaking Part 3, Finishing).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Fugitt discloses a method of manufacturing coated paperboard that meets all limitations of claim 1 except for the explicit thermo-roller temperature of "at least 250°F." Fugitt teaches passing a paperboard substrate through a calender whose rolls "may be steam heated" before applying a basecoat and topcoat. The key distinguishing feature added during prosecution was the 250°F temperature limitation. Papermaking, a seminal industry reference, allegedly remedies this by teaching that modern hard-nip calenders operate at elevated temperatures, with steam heating capable of reaching 338°F and hot oil heating capable of reaching over 428°F. Papermaking also discloses that high thermo-roll temperatures (e.g., over 392°F) are used in precalendering to achieve bulk savings, a goal consistent with the ’142 patent.
  • Motivation to Combine: A Person of Ordinary Skill in the Art (POSITA) would combine Fugitt’s process with the teachings of Papermaking to improve the final product's surface quality, uniformity, and smoothness. Since Papermaking teaches that high temperatures are an "active parameter" for achieving these known benefits, a POSITA would have been motivated to apply the specific temperature ranges disclosed in Papermaking to the steam-heated calender in Fugitt.
  • Expectation of Success: A POSITA would have a high expectation of success, as Papermaking describes well-known principles and established practices for calendering paperboard, including the direct relationship between higher temperatures and improved product characteristics.

Ground 2: Obviousness over Fugitt, Papermaking, and Gratton - Claims 1, 2, and 4 are obvious over Fugitt in view of Papermaking and Gratton.

• Prior Art Relied Upon: Fugitt (Application # 2009/0236062), Papermaking (2009 book), and Gratton (a 1988 TAPPI journal article on temperature-gradient calendering).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground builds on Ground 1 by adding Gratton as further evidence of the obviousness of using high temperatures. Gratton discloses "temperature-gradient (TG) calendering" as a technique to improve paper surface finish with less bulk reduction. Gratton specifically describes experiments on foodboard using a heated hard-nip calender with iron rolls heated to temperatures up to 210°C (410°F), which is well above the 250°F claimed threshold. For dependent claim 2, Gratton discloses nip loads that overlap with the claimed range. For dependent claim 4 (applying starch), Gratton discloses applying a pigmented starch coating in a size press prior to calendering.
  • Motivation to Combine: A POSITA seeking to optimize the process in Fugitt would look to specialized literature like Gratton, which specifically addresses TG calendering of foodboard. Gratton reinforces the teachings of Papermaking and provides a concrete example of using high temperatures to achieve the very same smoothness and low-density advantages touted by the ’142 patent. The combination would be a straightforward application of known principles to achieve a predictable result.
  • Expectation of Success: The expectation of success would be high, as Gratton explicitly concludes that TG calendering at high temperatures produces boards with lower roughness and higher gloss compared to conventional methods.

Ground 3: Obviousness over Fugitt, Papermaking, and Papermaking II - Claim 4 is obvious over Fugitt in view of Papermaking and Papermaking II.

• Prior Art Relied Upon: Fugitt (Application # 2009/0236062), Papermaking (2009 book), and Papermaking II (a 2000 book, Papermaking Science and Technology Book 11: Pigment Coating and Surface Sizing of Paper).
• Core Argument for this Ground:
  • Prior Art Mapping: This ground specifically targets the patentability of claim 4, which adds the step of applying starch to the substrate before it passes through the hot-hard calender. Petitioner asserted that Fugitt discloses a size press located before the calender. Papermaking II, from the same well-known book series as Papermaking, allegedly teaches that it is conventional to have a size press before coating and to apply low-consistency starch to the board surface. The stated purpose in Papermaking II is to improve stiffness and surface strength, which aligns with the functional properties mentioned in Fugitt.
  • Motivation to Combine: A POSITA would be motivated to apply the conventional starch sizing techniques from Papermaking II to the process in Fugitt. Since Fugitt already includes a size press in the appropriate location, implementing this standard industry practice to improve board properties would be a simple and obvious design choice.

4. Key Claim Construction Positions

• "paperboard substrate": Petitioner proposed this term be broadly construed as "a material that can be used to create paperboard structure." This includes various types like cartonboard, boxboard, and containerboard, as supported by the specification’s statement that "any paperboard material" may be used.
• "hot-hard calender": Petitioner proposed this term means "a calender defined by at least two rollers of suitable hardness... wherein at least one roller is heated to a temperature above ambient temperature." Petitioner argued that the prosecution history, where the examiner rejected claims over Fugitt's "steam heated" calender, supports a broad interpretation that is not limited by the 200°F temperature of the "traditional calender" mentioned in the patent's examples.

5. Arguments Regarding Discretionary Denial

• Petitioner argued that discretionary denial under 35 U.S.C. § 325(d) is inappropriate. While acknowledging that Fugitt was considered during prosecution, Petitioner contended it was only asserted in a single-reference rejection. The new references (Papermaking, Gratton, and Papermaking II) were not before the examiner. These references are not cumulative because they directly address the elevated temperature limitation (at least 250°F), which was the sole basis for allowance. Petitioner asserted that the examiner materially erred by accepting the Patent Owner's argument that 250°F was "significantly hotter" than Fugitt's "steam heating" without conducting a further search, which would have revealed that steam heating temperatures were known to reach up to 338°F.

6. Relief Requested

• Petitioner requests institution of an inter partes review and cancellation of claims 1, 2, and 4-24 of the ’142 patent as unpatentable.