New NGC Inc v. United States Gypsum Co

1. Case Identification

• Case #: IPR2017-01088
• Patent #: 7,425,236
• Filed: March 17, 2017
• Petitioner(s): NEW NGC, INC. dba National Gypsum Company
• Patent Owner(s): United States Gypsum Company
• Challenged Claims: 2

2. Patent Overview

• Title: Method of Preparing Set Gypsum Product Containing Enhancing Material
• Brief Description: The ’236 patent discloses a method for producing set gypsum products (e.g., gypsum boards, plasters) by adding an aqueous solution of "enhancing materials" to a mixture of calcined gypsum, water, and an accelerator. The enhancing materials are intended to improve properties such as strength and sag resistance.

3. Grounds for Unpatentability

Ground 1: Claim 2 is obvious over Graux in view of Kerr.

• Prior Art Relied Upon: Graux (Patent 5,932,001) and Kerr (Patent 2,884,413).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Graux disclosed a method of producing set gypsum products that included all the key components of claim 2: calcined gypsum, water, accelerators, and an enhancing material (sodium trimetaphosphate, or STMP, used to crosslink starch). Graux’s composition is mixed with water and allowed to set, forming an interlocking matrix. The key element allegedly missing from Graux alone was the explicit step of pre-dissolving the enhancing material in water before adding it to the gypsum mixture.
  • Motivation to Combine: Petitioner contended that a person of ordinary skill in the art (POSITA) would combine Graux with Kerr because Graux taught using STMP and starch to improve the quality of gypsum products, while Kerr taught the fundamental chemistry of using STMP to crosslink starch. Kerr explicitly disclosed that the most effective way to achieve this crosslinking is to add the phosphate (STMP) to an aqueous starch slurry. A POSITA would therefore be motivated to apply Kerr’s teaching to Graux’s process to ensure the STMP was chemically active and the process was more efficient and reliable.
  • Expectation of Success: A POSITA would have a reasonable expectation of success because combining the references involved applying known chemical principles (dissolving a reagent in water to make it active, per Kerr) to a known process (Graux's gypsum composition) to achieve a predictable improvement in the process.

Ground 2: Claim 2 is obvious over Satterthwaite in view of Kerr.

• Prior Art Relied Upon: Satterthwaite (Patent 3,234,037) and Kerr (Patent 2,884,413).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner asserted that Satterthwaite disclosed manufacturing acoustical ceiling tiles from a mixture of water, gypsum, and other ingredients, including a starch treated with STMP to increase resistance to sag. While Satterthwaite did not explicitly recite an accelerator, Petitioner argued its inclusion was admitted prior art. Similar to Ground 1, the argument relied on Kerr to supply the teaching of pre-dissolving the STMP in water.
  • Motivation to Combine: The motivation was analogous to Ground 1. A POSITA reading Satterthwaite would understand the benefit of using STMP to improve the properties of a gypsum-based product. To optimize this known benefit, the POSITA would turn to a reference like Kerr, which taught the preferred and chemically necessary method of dissolving STMP in water to make it reactive for crosslinking starch.
  • Expectation of Success: Success would be expected because the combination merely involved applying a standard chemical preparation step (dissolving a reactant) taught by Kerr to the components already disclosed in Satterthwaite to achieve the desired property improvements.

Ground 3: Claim 2 is obvious over Conroy in view of Johnstone.

• Prior Art Relied Upon: Conroy (Patent 4,965,031) and Johnstone (Patent 4,372,814).
• Core Argument for this Ground:
  • Prior Art Mapping: Petitioner argued that Conroy disclosed a continuous process for making gypsum board that included mixing calcined gypsum, water, and various additives, including "hardeners/accelerators" such as boric acid. Petitioner contended that boric acid qualified as an "enhancing material" under the proper claim construction as it was known to increase compressive strength. Johnstone was relied upon for its teaching of including a solution of boric acid in a gypsum wallboard composition.
  • Motivation to Combine: A POSITA, seeking to incorporate the boric acid hardener taught by Conroy, would be motivated to do so in the most effective and common manner. Johnstone taught that using an aqueous solution of boric acid was a known method for its inclusion in gypsum products. Using a solution would provide more accurate metering and more efficient, homogeneous incorporation into the gypsum slurry, representing a simple and predictable process optimization.
  • Expectation of Success: A POSITA would have a high expectation of success because adding an ingredient as a solution rather than a solid powder is a routine and well-understood technique in the art for improving process control and product uniformity.

4. Key Claim Construction Positions

• "enhancing material(s)": Petitioner argued this term should be construed as "an additive that improves at least one of resistance to permanent deformation, strength, and dimensional stability in set gypsum-containing products."
  • This broad construction was central to Petitioner's arguments, particularly for Ground 3, as it allowed boric acid (disclosed in Conroy as a "hardener/accelerator") to qualify as an enhancing material. Petitioner supported this construction by contrasting the open-ended use of the term in challenged claim 2 with other, un-challenged claims of the ’236 patent that recited a specific Markush group of chemicals for the enhancing material, implying claim 2 was intentionally broader.

5. Relief Requested

• Petitioner requested institution of an inter partes review and cancellation of claim 2 of the ’236 patent as unpatentable.