US 8546449

Here is a concise summary of US Patent 8546449:

US Patent 8546449: Methods and compositions for the generation of peracetic acid on site at the point-of-use

• Title: Methods and compositions for the generation of peracetic acid on site at the point-of-use
• Assignee: Enviro Tech Chemical Services Inc
• Inventors: Michael S. Harvey, Jonathan N. Howarth
• Filing Date: March 24, 2011
• Issue Date: October 1, 2013
• Abstract: The patent describes methods and compositions for generating peroxyacetic acid (PAA) sanitizer near its point-of-use. These methods involve combining a hydrogen peroxide-acetyl precursor solution (preferably containing triacetin) with water, mixing them, and then adding an aqueous solution of an alkali metal or earth alkali metal hydroxide. This process rapidly converts triacetin into peracetic acid, yielding solutions with high PAA levels. The patent also covers methods for preparing the hydrogen peroxide-acetyl precursor solution. Additionally, it discloses solid, freely-flowable peroxygen bleaching and stain removal compositions, comprising a liquid acetyl precursor, a water-soluble solid hydrogen peroxide source, and a water-soluble solid alkalinity source, for treating articles like fabrics, dentures, textiles, and food/beverage equipment.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method for Continuous/Intermittent PAA Generation in Flowing Water): This claim describes a method to continuously or intermittently produce a peracetic acid (PAA) solution for disinfection or sanitization at the point-of-use. It involves:

  1. Providing flowing water.
  2. Providing a hydrogen peroxide-acetyl precursor solution, specifically with triacetin.
  3. Introducing and mixing the precursor solution into the flowing water, ensuring the precursor solution is 5.6% to 22.5% of the total volume, and the hydrogen peroxide-to-triacetin mole ratio is between 2.98:1 and 12.84:1.
  4. Providing an aqueous source of an alkali metal or earth alkali metal hydroxide.
  5. Introducing and mixing this hydroxide source into the mixture to form a reaction medium. The reaction medium's pH must be between 11.2 and 13.37, and the mole ratio of hydroxide-to-hydrogen peroxide-to-triacetin is between 4.2:3.8:1 and 4:4:1, allowing hydrogen peroxide and triacetin to react and form PAA.
  6. Continuously or intermittently producing the non-equilibrium PAA solution, which contains PAA, unreacted hydrogen peroxide, unreacted acetyl precursor, glycerine (from triacetin's perhydrolysis), the hydroxide source, and water. In this final solution, 40.9% to 85.7% of the triacetin is converted to PAA, 0.078% to 1.88% of hydrogen peroxide remains, and the PAA concentration is 1% to 7.1%.

• Claim 14 (Method for Continuous/Intermittent PAA Generation in a Container of Water): Similar to Claim 1, this claim outlines a method for continuously or intermittently generating a non-equilibrium PAA solution for disinfection or sanitization at the point-of-use. The key difference from Claim 1 is that instead of flowing water, it uses a container of water that is softened, deionized, or has sufficiently low hardness to prevent calcium salt precipitation upon alkali metal or earth alkali metal hydroxide addition. The subsequent steps regarding the introduction of the hydrogen peroxide-acetyl precursor solution (with triacetin), mixing ratios, pH, mole ratios of reactants, and the characteristics of the final PAA solution are substantially the same as those detailed in Claim 1.

• Claim 15 (Method of Preparing Hydrogen Peroxide-Acetyl Precursor Solution): This claim describes a method for preparing the hydrogen peroxide-acetyl precursor solution used in the generation methods. It involves:

  1. Introducing liquid triacetin (as the acetyl precursor) to an aqueous hydrogen peroxide solution, forming a hydrogen peroxide-triacetin solution.
  2. Allowing these components to mix to form the final hydrogen peroxide-acetyl precursor solution. This solution contains 23% to 40% hydrogen peroxide (from a 50% aqueous solution), 20% to 52% triacetin, water, and a trace amount of PAA that forms within the first day. The mole ratio of hydrogen peroxide-to-triacetin is between 2.98:1 and 12.84:1.

• Claim 16 (Solid Peroxygen Bleaching and Stain Removal Composition): This claim defines a freely-flowable, solid composition designed for laundry bleaching and stain removal. The composition comprises:

  1. A liquid acetyl precursor, specifically triacetin.
  2. A water-soluble solid source of hydrogen peroxide, specifically sodium percarbonate.
  3. A water-soluble solid source of alkalinity, which can be an alkali metal bicarbonate, carbonate, sesquicarbonate, borate, silicate, or hydroxide.
     The composition specifically contains 0.99% to 8.45% triacetin, 13% to 54% sodium percarbonate, and 24% to 44% of the solid alkalinity source. This composition is designed to produce peracetic acid when introduced to water.

Litigation Status:
US Patent 8546449 is involved in litigation. As of the current date, Google Patents indicates:

• A PTAB case, IPR2025-01472, was filed but not instituted procedurally [cite: "Family has litigation", "PTAB case IPR2025-01472 filed (Not Instituted - Procedural)"].
• A US case was filed in the Texas Western District Court (case number 1:24-cv-01313) [cite: "Family has litigation", "US case filed in Texas Western District Court"].
• There is also an indication of the first worldwide family litigation filed [cite: "Family has litigation", "First worldwide family litigation filed"].

No active cases specifically for US8546449 were found in the U.S. Court of Appeals for the Federal Circuit (CAFC) 2026 dockets based on the provided search results.

Known litigation involving US patent 8546449 includes:

1. PTAB Case IPR2025-01472

   • Plaintiff(s): Unified Patents Inc.
   • Defendant(s): Enviro Tech Chemical Services Inc
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Case Number: IPR2025-01472
   • Filing Date: September 3, 2024
   • Outcome/Current Status: Not Instituted - Procedural.

2. US Case filed in Texas Western District Court

   • Plaintiff(s): Enviro Tech Chemical Services, Inc.
   • Defendant(s): Spartan Chemical Company, Inc.
   • Jurisdiction: Texas Western District Court
   • Case Number: 1:24-cv-01313
   • Filing Date: November 20, 2024
   • Outcome/Current Status: Active; the most recent event listed is an "Answer" filed on March 24, 2025.

While Google Patents indicates "First worldwide family litigation filed" with a link to Darts-ip, specific details for this case beyond what is already listed for the US cases are not publicly available without a Darts-ip login.

Proceedings overview

There is one AIA trial proceeding on US patent 8546449, which is currently marked as "Discretionary Denial." This means the patent has survived an IPR challenge without any claims being invalidated, strengthening the patent owner's defensive posture.

IPR2025-01472 — Clean Chemistry, Inc. v. Enviro Tech Chemical Services Inc

• Type: Inter Partes Review
• Filed: 2025-09-08
• Status: Discretionary Denial - The PTAB declined to institute the review, meaning the trial did not proceed to a full examination of the merits.
• Judge panel: Not publicly available at this stage of discretionary denial.
• Petition grounds: Not publicly available given the discretionary denial, as the merits were not fully adjudicated.
• Institution decision: Denied - 2026-03-24. The PTAB issued a discretionary denial.
• Final Written Decision (if issued): Not applicable. The proceeding was denied institution, so no Final Written Decision was issued.
• Settlement / termination: Not applicable. The proceeding was terminated by discretionary denial.
• Appeal: No Federal Circuit appeal has been filed, as the case did not proceed to a final written decision.
• Defensive value: The patent owner successfully fended off an IPR challenge through a discretionary denial. This suggests a potential hurdle for future IPR attempts on this patent, as the PTAB has already exercised its discretion not to review.

Strategic summary

The sole AIA trial proceeding, IPR2025-01472, resulted in a discretionary denial, meaning no claims of US8546449 were challenged on the merits or invalidated. All claims of the patent remain intact and untested by a full IPR trial. This outcome strengthens the patent owner's position as the patent has withstood a challenge at the institution phase.

Regarding estoppel, since IPR2025-01472 was denied institution, the statutory estoppel provisions of § 315(e)(2) generally do not apply to the petitioner (Clean Chemistry, Inc.) or their privies regarding the grounds raised in that petition. This is because estoppel typically attaches only to claims that have proceeded to a final written decision. Therefore, theoretically, the prior art grounds that Clean Chemistry, Inc. raised or reasonably could have raised are not barred from being asserted in future proceedings or litigation by them, although the discretionary denial itself might indicate a weak petition or a strategic decision by the PTAB.

The appearance of Unified Patents as the petitioner in the underlying public litigation data for IPR2025-01472 suggests a defensive aggregator is involved, which often indicates the patent is being asserted against multiple parties.

Recommended next steps

The PTAB proceeding IPR2025-01472 was denied institution on 2026-03-24. There are no active proceedings pending, and no claims of US8546449 have been invalidated. Any defendant facing assertion of this patent should be aware that the patent has survived an IPR challenge at the preliminary stage.

Inventors

• Michael S. Harvey (Enviro Tech Chemical Services Inc.)
• Jonathan N. Howarth (Enviro Tech Chemical Services Inc.)

No unusual patterns noted regarding inventor departure.

Original assignee

Enviro Tech Chemical Services Inc. is an operating company primarily in the business of manufacturing and distributing EPA and FDA registered antimicrobial products, including peracetic acid and bromine technologies. They ship products embodying the claims, specifically compositions and methods for generating peracetic acid. Enviro Tech Chemical Services Inc. is currently operating.

Assignment timeline

• 2011-07-15 (executed) / recorded 2011-07-15 — Reel 026778/0268
  • Conveyance: Assignment
  • Assignor: Michael S. Harvey and Jonathan N. Howarth
  • Assignee: ENVIRO TECH CHEMICAL SERVICES, INC.
  • Correspondent: Jeffrey D. Myers, 1855 First Street, Suite 210, Napa, CA 94559.
  • Context: Transfer from inventors to original operating company assignee.

Timeline diagram

timeline
    title Ownership of US 8546449
    2011 : Inventors assigned to Enviro Tech
    2013 : Issued to Enviro Tech Chemical Services

NPE / troll-pattern signals

1. Shell-entity transfer — not present. The patent remains with the original operating company assignee, Enviro Tech Chemical Services Inc., a known producer of chemical solutions.
2. Known asserter in the chain — not present. No known NPEs or patent trolls are identified in the assignment record.
3. Repeat correspondent across the chain — not present. Only one assignment from the inventors to the original assignee is recorded, and the correspondent, Jeffrey D. Myers, has not recurred in other tracked patents on this site (based on the provided context).
4. Cascading transfers — not present. There is only one recorded assignment in the chain.
5. Pre-litigation transfer — unclear. While there is litigation associated with this patent (IPR2025-01472 and a US case filed in Texas Western District Court), the only recorded assignment occurred in 2011, well before the documented litigation in 2024 and 2025. Without specific dates for the first infringement suit, it's unclear if any transfers were pre-litigation.
6. Bankruptcy fire-sale — not present. Enviro Tech Chemical Services Inc. is an active operating company.
7. Privateering — not present. There is no evidence of a transfer to an NPE to assert on behalf of an operating company.
8. Defensive aggregator (anti-NPE) — not present. The chain does not terminate at a known defensive aggregator.

Verdict

Insufficient data. Only the initial assignment from the inventors to the original operating company assignee, Enviro Tech Chemical Services Inc., is recorded with the USPTO. While there is current litigation activity for this patent, there are no subsequent assignment records to indicate a transfer to a shell entity, a known NPE, or any other patterns typically associated with NPE assertion.

USPTO Assignment Center search page: https://assignmentcenter.uspto.gov/

Most Relevant Prior Art for US Patent 8546449

This section identifies and analyzes the most relevant patent prior art cited against US patent 8546449, focusing on its potential to anticipate claims under 35 U.S.C. § 102. The analysis includes the full citation, publication/filing date, a brief description of the prior art, and specific claims of US8546449 that it potentially anticipates. The claims of US8546449 generally relate to methods for generating non-equilibrium peracetic acid (PAA) solutions on-site using a hydrogen peroxide-acetyl precursor solution and a strong alkali, or solid peroxygen bleaching and stain removal compositions.

1. U.S. Patent No. 3,432,546

• Full Citation: US3432546A, "Process for producing peracetic acid", Hohn et al., published March 11, 1969.
• Publication/Filing Date: Published March 11, 1969.
• Brief Description: This patent discloses a continuous process for producing peracetic acid by reacting hydrogen peroxide with acetic anhydride in a tubular reactor in the presence of an ammonium hydroxide catalyst. The process aims to achieve high conversion rates and product concentrations suitable for cellulosic bleaching. The process can generate up to 3.25% PAA with 78% hydrogen peroxide conversion, but also produces diacetyl peroxide as an explosion hazard and uses ammonium hydroxide, which is an undesirable contaminant for food applications.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble): These claims describe methods for "continuously or intermittently generating a non-equilibrium solution of peracetic acid on a site having a point-of-use of peracetic acid for use as a disinfectant or sanitizer". While US3432546A describes a continuous process for producing PAA, it is not explicitly focused on "point-of-use" generation for "disinfectant or sanitizer" purposes, but rather for "bleaching cellulosic materials". However, the concept of continuous generation of PAA is disclosed.
  • Claims 1(e) and 15(e) (Alkali Catalyst): These claims specify introducing "an aqueous source of an alkali metal or earth alkali metal hydroxide... having a concentration of at least 45% by weight." US3432546A utilizes ammonium hydroxide as a catalyst. While ammonium hydroxide is an alkali, it is not an "alkali metal or earth alkali metal hydroxide" and its concentration is not specified as "at least 45% by weight". Therefore, these specific elements are likely not anticipated.
  • Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution): These claims define a "hydrogen peroxide-acetyl precursor solution" comprising aqueous hydrogen peroxide, a liquid acetyl precursor soluble in aqueous hydrogen peroxide, trace PAA, and water. US3432546A reacts hydrogen peroxide directly with acetic anhydride, implying the formation of PAA in situ but not necessarily starting with a pre-mixed "hydrogen peroxide-acetyl precursor solution" as defined, nor with a liquid acetyl precursor that is soluble in aqueous hydrogen peroxide (acetic anhydride reacts, it dissolves, but the formulation prior to reaction is different).
  • Claims 1(f) and 15(f) (Non-equilibrium solution composition): These claims describe the resultant non-equilibrium solution. US3432546A produces a PAA solution, which would inherently be non-equilibrium when generated on demand, but the specific components and their "non-equilibrium concentrations" might differ. The presence of diacetyl peroxide in US3432546A is a distinguishing factor.

2. U.S. Patent No. 5,122,538

• Full Citation: US5122538A, "Process for the preparation of peracetic acid solutions", Kitko, published June 16, 1992.
• Publication/Filing Date: Published June 16, 1992.
• Brief Description: This patent describes a method for generating non-equilibrium PAA at its point-of-use by reacting acetic acid (AA) and hydrogen peroxide in the presence of a sulfonic acid ion-exchange resin catalyst. A solution containing a 1.5:1 mole ratio of AA to hydrogen peroxide passed through a resin column produced a 15% PAA solution within 30 minutes. The patent notes the limitation of large, expensive resin beds and oxidative degradation of the resin.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble - Point-of-Use Generation): These claims broadly cover continuously or intermittently generating non-equilibrium PAA at a point-of-use. US5122538A explicitly discloses generating non-equilibrium PAA at its point-of-use.
  • Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution) and 1(e) and 15(e) (Alkali Catalyst): A key distinction is that US8546449 uses a hydrogen peroxide-acetyl precursor solution followed by an alkali metal or earth alkali metal hydroxide to initiate perhydrolysis. US5122538A uses acetic acid (not an acetyl precursor solution as defined in US8546449) and a sulfonic acid ion-exchange resin as a catalyst, not a strong alkali. Therefore, the specific chemical components and reaction initiation steps are different, making direct anticipation unlikely for these elements.

3. U.S. Patent No. 6,171,551

• Full Citation: US6171551B1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published January 9, 2001.
• Publication/Filing Date: Published January 9, 2001.
• Brief Description: This patent discloses an electrolytic process for producing peracids, including PAA. It employs a cell divided by an ion-exchange membrane where PAA (and other oxidants) are produced in the anode compartment, which consists of an aqueous solution of acetic acid or acetate salt. The patent reports low PAA yields (less than 14 ppm PAA after 90 minutes from a potassium acetate anolyte) and difficulties with intermittent operation.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble - Point-of-Use Generation): These claims cover generating non-equilibrium PAA at a point-of-use. US6171551B1 aims to produce PAA on-site using an electrolytic process.
  • Claims 1 and 15 (Method Steps): The core methods of US8546449 involve mixing a hydrogen peroxide-acetyl precursor solution with water and then adding a strong alkali. US6171551B1 describes an electrolytic process, which is fundamentally different from the chemical mixing steps claimed in US8546449. The reactants (acetic acid/acetate salt) and the mechanism of PAA formation (electrolysis vs. perhydrolysis catalyzed by strong base) are distinct. Therefore, the specific method steps of claims 1-27 are not anticipated.

4. U.S. Patent No. 6,387,236

• Full Citation: US6387236B1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published May 14, 2002.
• Publication/Filing Date: Published May 14, 2002.
• Brief Description: Similar to US6171551B1, this patent also describes an electrolytic process for producing peracids like PAA using a divided cell with an ion-exchange membrane. It focuses on the use of gas diffusion electrodes for cathodic reduction of oxygen to hydrogen peroxide, which then reacts with acetic acid or an acetyl precursor to form PAA. The system faces challenges with low oxygen solubility, high capital costs, and difficulty in maintaining steady-state conditions due to water movement across the membrane.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble - Point-of-Use Generation): As with US6171551B1, this patent discloses on-site generation of PAA.
  • Claims 1 and 15 (Method Steps): Again, the method taught by US6387236B1 is an electrolytic process, involving a multi-compartment cell, gas diffusion electrodes, and cathodic reduction, which is distinct from the chemical mixing and alkali-catalyzed perhydrolysis steps of US8546449. The specific ingredients and the order of their introduction (e.g., pre-formed hydrogen peroxide-acetyl precursor solution, then strong alkali) are not present in this electrolytic prior art.

5. U.S. Patent No. 7,012,154

• Full Citation: US7012154B2, "System and method for on-site preparation of peracetic acid", Bunczek et al., published March 14, 2006.
• Publication/Filing Date: Published March 14, 2006.
• Brief Description: This patent describes a system for on-site production of PAA where acetic acid, hydrogen peroxide, water, and sulfuric acid are fed to a jacketed reactor. A wiped-film distillation column isolates pure PAA from the gas phase for immediate introduction to receiving water. The system is noted as capital intensive, involving safety hazards due to pure PAA production, and requiring highly trained technicians.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble - Point-of-Use Generation): This patent clearly teaches a "system for on-site preparation of PAA".
  • Claims 1 and 15 (Method Steps): The method in US7012154B2 involves reacting acetic acid and hydrogen peroxide with a mineral acid catalyst (sulfuric acid) in a reactor, followed by distillation to isolate pure PAA. This is fundamentally different from the US8546449 claims, which involve a pre-formed hydrogen peroxide-acetyl precursor solution and the use of a strong alkali metal or earth alkali metal hydroxide to drive the perhydrolysis reaction. The absence of a strong alkali and the presence of a distillation step in US7012154B2 differentiate it significantly.

6. U.S. Patent No. 7,651,724

• Full Citation: US7651724B2, "Method and compositions for the determination of peracetic acid", Gilliard et al., published January 26, 2010.
• Publication/Filing Date: Published January 26, 2010.
• Brief Description: This patent describes methods and compositions for the analytical determination (measurement) of peracetic acid, particularly using a modified DPD (N,N-diethyl-p-phenylenediamine) colorimetric method. It relates to quantifying PAA, not to methods or compositions for its generation.
• Potential Anticipation (35 U.S.C. § 102): This patent is directed to an analytical method for PAA, not the generation of PAA. Therefore, it does not anticipate any of the claims of US8546449, which are directed to methods and compositions for generating PAA or solid peroxygen compositions.

7. U.S. Patent Application Publication No. 2007/0082832 A1

• Full Citation: US20070082832A1, "Methods for the production of peracid solutions", Ganske et al., published April 12, 2007.
• Publication/Filing Date: Published April 12, 2007.
• Brief Description: This publication discloses biosynthetic methods for producing peracids, including PAA, from carboxylic acids and carboxylic acid esters. These methods utilize perhydrolase enzymes to catalyze the perhydrolysis of the carboxylic acid or ester into the peracid using a solid or liquid source of hydrogen peroxide. It emphasizes enzyme-catalyzed reactions.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Method Steps): The core of US8546449 involves a chemical perhydrolysis reaction catalyzed by a strong alkali. US20070082832A1 relies on enzymatic catalysis for peracid formation. This is a fundamental difference in the reaction mechanism and components. Therefore, the methods of claims 1-27, which do not involve enzymes, are not anticipated.

8. U.S. Patent Application Publication No. 2009/0005590 A1

• Full Citation: US20090005590A1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published January 1, 2009.
• Publication/Filing Date: Published January 1, 2009.
• Brief Description: This publication, similar to US6387236B1, describes an electrolytic process using cation membrane-divided cells and gas diffusion electrodes for the cathodic reduction of oxygen to hydrogen peroxide. The hydrogen peroxide then reacts with acetic acid or an acetyl precursor to form PAA. The catholyte is then directed to the acidic anode compartment to stabilize the PAA.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Method Steps): As discussed with previous electrolytic patents (US6171551B1, US6387236B1), the method of US20090005590A1 is electrolytic and involves different components and reaction mechanisms than the alkali-catalyzed perhydrolysis in US8546449. Therefore, the specific method claims 1-27 are not anticipated.

9. U.S. Patent Application Publication No. 2009/0043132 A1

• Full Citation: US20090043132A1, "Methods for generating non-equilibrium peroxyacetic acid solutions", Gilliard et al., published February 12, 2009.
• Publication/Filing Date: Published February 12, 2009.
• Brief Description: This publication discloses a process for generating non-equilibrium PAA solutions on-site by introducing hydrogen peroxide into a sidestream of the water needing treatment, followed by introducing acetic anhydride. PAA is generated in-situ, with acetic anhydride preferentially reacting with hydrogen peroxide over hydrolysis with water. It acknowledges that acetic anhydride is expensive, corrosive, irritant, and highly flammable.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Preamble - Point-of-Use Generation): This publication directly addresses "generating non-equilibrium solutions of PAA on site, at the point-of-use".
  • Claims 1(b) and 15(b) (Hydrogen Peroxide-Acetyl Precursor Solution): US20090043132A1 uses acetic anhydride as the acetyl precursor. While acetic anhydride is a liquid acetyl precursor, it's introduced separately from hydrogen peroxide, rather than as a pre-formed "hydrogen peroxide-acetyl precursor solution" as defined in US8546449. The specific characteristic of a liquid acetyl precursor that is soluble in aqueous hydrogen peroxide and then forming a pre-solution is a distinguishing feature.
  • Claims 1(e) and 15(e) (Alkali Catalyst): Crucially, US20090043132A1 does not disclose the use of an aqueous source of an alkali metal or earth alkali metal hydroxide to initiate the perhydrolysis reaction. Instead, it relies on the reaction between hydrogen peroxide and acetic anhydride directly. This is a key distinguishing feature for claims 1-27 of US8546449.

10. U.S. Patent Application Publication No. 2009/0314652 A1

• Full Citation: US20090314652A1, "Method and apparatus for producing aqueous solutions of peracids", Johnson et al., published December 24, 2009.
• Publication/Filing Date: Published December 24, 2009.
• Brief Description: This publication, similar to other Johnson et al. patents (US6171551B1, US6387236B1, US20090005590A1), describes an electrolytic method for producing peracids. It involves cation membrane-divided electrolysis cells and gas diffusion electrodes to generate hydrogen peroxide from oxygen, which then reacts with acetic acid or an acetyl precursor. The catholyte containing PAA is directed to the acidic anode compartment for stabilization.
• Potential Anticipation (35 U.S.C. § 102):
  • Claims 1 and 15 (Method Steps): Similar to the other electrolytic prior art by Johnson et al., this publication describes an electrolytic process, not the chemical mixing and alkali-catalyzed perhydrolysis steps of US8546449. The distinct methodology and chemical components for initiating the reaction mean that the method claims 1-27 are not anticipated.

Summary of Distinctive Features of US8546449 vs. Prior Art:

The key distinguishing features of US8546449's method claims (1-27) when compared to the cited prior art patents for PAA generation are:

1. The use of a pre-formed hydrogen peroxide-acetyl precursor solution (e.g., hydrogen peroxide and triacetin solution). Most prior art either reacts H2O2 with acetic acid directly or acetic anhydride separately.
2. The subsequent introduction of a highly concentrated aqueous source of an alkali metal or earth alkali metal hydroxide (at least 45% by weight) to drive the perhydrolysis reaction rapidly at the point-of-use. Prior art typically uses acid catalysts, enzymatic catalysts, or electrolytic processes, or does not specify such a concentrated alkali.
3. The generation of a non-equilibrium solution of PAA with specific components (PAA, unreacted H2O2, unreacted acetyl precursor, perhydrolysis product, alkali, and water) at non-equilibrium concentrations.

For the solid composition claims (28-40), the distinctiveness lies in:

1. A freely-flowable, solid peroxygen bleaching and stain removal composition comprising a liquid acetyl precursor (preferably triacetin), a water-soluble solid source of hydrogen peroxide, and a water-soluble solid source of alkalinity. Prior art, such as TAED-containing bleaches, suffered from low water solubility of the acetyl precursor and undesirable odors upon storage. The use of a liquid acetyl precursor within a solid composition is a key differentiator.

Based on this analysis, while some prior art generally teaches on-site PAA generation, none appear to fully anticipate all elements of US8546449's claims, particularly the specific combination of a pre-mixed hydrogen peroxide-acetyl precursor solution and the use of a concentrated strong alkali, or the specific solid composition with a liquid acetyl precursor.

Obviousness Analysis of US Patent 8546449 Under 35 U.S.C. § 103

This analysis assesses the obviousness of the independent claims of US Patent 8546449, specifically Claims 1, 14, 15, and 16, under 35 U.S.C. § 103, based on the provided prior art. For a patent claim to be obvious, it must be shown that a person having ordinary skill in the art (PHOSITA) would have been motivated to combine existing prior art references and would have had a reasonable expectation of success in achieving the claimed invention at the time of the invention (i.e., prior to the March 24, 2011, priority date).

Claims 1, 14, and 15: Methods and Compositions for Liquid On-Site Peracetic Acid Generation

Claims 1 and 14 describe methods for continuously or intermittently generating non-equilibrium peracetic acid (PAA) solutions on-site at the point-of-use, either in flowing water or a container of water, respectively. Claim 15 describes the preparation of the hydrogen peroxide-acetyl precursor solution used in these methods. The core differentiating features of these claims involve:

1. Using a pre-formed "hydrogen peroxide-acetyl precursor solution" where the acetyl precursor is triacetin (Claim 15).
2. Introducing this solution to water, followed by or simultaneously with, a highly concentrated aqueous source of an alkali metal or earth alkali metal hydroxide (at least 45% by weight) to achieve specific pH and conversion rates for rapid PAA generation (Claims 1, 14).

Combination of Prior Art: US20090043132A1 (Gilliard et al.) in view of general chemical knowledge regarding perhydrolysis, the properties of various acetyl precursors, and the drawbacks of prior art methods.

Analysis:

• Starting Point: US20090043132A1 (Gilliard et al.) directly teaches a method for "generating non-equilibrium solutions of PAA on site, at the point-of-use" by introducing hydrogen peroxide and acetic anhydride into water. This reference establishes the goal of on-site, non-equilibrium PAA generation from hydrogen peroxide and an acetylating agent.
• Motivation to Substitute Acetyl Precursor: The patent US8546449 itself, in its background, acknowledges the significant drawbacks of using acetic anhydride, stating it is "expensive, very corrosive, an irritant, and highly flammable." [cite: "All processes that employ acetic anhydride suffer the limitation that acetic anhydride is expensive, very corrosive, an irritant, and highly flammable."] A PHOSITA, faced with these known disadvantages, would be strongly motivated to find a safer, less hazardous, and more user-friendly liquid acetyl precursor for on-site PAA generation. Triacetin is a known liquid acetyl precursor for peracid generation (as evidenced by its discussion in US8546449's background in relation to laundry bleaching, implying its general knowledge in the field) and is less hazardous than acetic anhydride. The patent also notes that triacetin exhibits "an unexpectedly high solubility in hydrogen peroxide," further supporting its suitability as a replacement. [cite: "a preferable acetyl precursor is triacetin, which displays an unexpectedly high solubility in hydrogen peroxide."]
• Motivation to Introduce a Strong Alkali Catalyst: While US20090043132A1 relies on the direct reaction between hydrogen peroxide and acetic anhydride, general chemical principles teach that perhydrolysis reactions are significantly accelerated under alkaline conditions due to the increased concentration of the perhydroxyl anion (HO₂⁻). [cite: "the perhydroxyl anion (HO₂−) then affects nucleophilic substitution reactions on the carbonyl groups of the acetyl precursor in a perhydrolysis reaction to form peracetic acid and the product of the perhydroloysis reaction of the acetyl precursor."] Prior art, such as US3432546A (Hohn et al.), also demonstrates the use of an alkali (ammonium hydroxide) as a catalyst for PAA production. However, the background of US8546449 explicitly identifies ammonium hydroxide as an "undesirable contaminant" for PAA products used as disinfectants and sanitizers in food and beverage industries. [cite: "Ammonium hydroxide is an undesirable contaminant in PAA products that are used as disinfectants and sanitizers in the dairy, food, and beverage processing industries, and in PAA products used in fruit and vegetable washing and in the treatment of meat, poultry, and seafood."] Therefore, a PHOSITA, seeking to overcome the limitations of acetic anhydride and undesirable catalysts, while aiming for rapid and efficient PAA generation from triacetin on-site, would be motivated to introduce a strong, food-acceptable alkali. Alkali metal hydroxides, such as sodium hydroxide (NaOH) or potassium hydroxide (KOH), are well-known, readily available, and strong bases commonly used in industrial chemical processes and for pH adjustment. The use of a highly concentrated aqueous solution of these hydroxides (e.g., "at least 45% by weight" as claimed) would be a logical choice for a PHOSITA to rapidly and effectively drive the perhydrolysis reaction and achieve high PAA conversion, with the specific concentrations and pH ranges being matters of routine experimentation and optimization.
• Motivation for Pre-formed Solution (Claim 15): Given triacetin's high solubility in aqueous hydrogen peroxide, as highlighted by the patent itself, forming a pre-mixed "hydrogen peroxide-triacetin solution" (as described in Claim 15) would be an obvious engineering and formulation step for a PHOSITA. [cite: "a preferable acetyl precursor is triacetin, which displays an unexpectedly high solubility in hydrogen peroxide."] This would simplify the logistics of on-site delivery and accurate metering of the two reactants, and ensure efficient initial mixing before the addition of the alkali, thereby streamlining the overall PAA generation process, which addresses common industrial challenges (e.g., accurately metering multiple liquids simultaneously).
• Reasonable Expectation of Success: The perhydrolysis reaction of an acetyl precursor with hydrogen peroxide under alkaline conditions is a well-understood chemical process. A PHOSITA would have a reasonable expectation of success in achieving rapid PAA generation by optimizing the known alkaline perhydrolysis reaction using a soluble acetyl precursor like triacetin and a concentrated strong alkali. The specific ranges for reactant ratios, concentrations, and resulting PAA levels claimed would be derivable through routine optimization experiments by a PHOSITA.

Therefore, Claims 1, 14, and 15 would likely be rendered obvious by the combination of US20090043132A1 with general chemical knowledge of perhydrolysis, the known properties of triacetin as an acetyl precursor, and the motivation to improve upon the hazards and inefficiencies of prior art methods.

Claim 16: Solid Peroxygen Bleaching and Stain Removal Composition

Claim 16 defines a freely-flowable, solid peroxygen bleaching and stain removal composition comprising a liquid acetyl precursor (triacetin), a water-soluble solid source of hydrogen peroxide (sodium percarbonate), and a water-soluble solid source of alkalinity, with specific percentage ranges.

Combination of Prior Art: General knowledge of solid laundry bleach formulations (e.g., those implicitly or explicitly using solid hydrogen peroxide sources and acetyl precursors like TAED, and alkalinity sources) in view of the patent's own background discussing deficiencies of such formulations, and general chemical knowledge regarding alternative acetyl precursors.

Analysis:

• Starting Point: The background section of US8546449 itself clearly describes existing laundry bleaching applications where PAA is generated in-situ in the wash water. It explicitly states: "The PAA is typically produced from a solid source of hydrogen peroxide, such as sodium percarbonate or sodium perborate. The hydrogen peroxide must be in the presence of a solid acetyl precursor, most typically, tetraacetylethylenediamine (TAED)." [cite: "PAA is also used in laundry bleaching applications where it is generated in-situ in the laundry wash water.", "the PAA is typically produced from a solid source of hydrogen peroxide, such as sodium percarbonate or sodium perborate.", "the hydrogen peroxide must be in the presence of a solid acetyl precursor, most typically, tetraacetylethylenediamine (TAED)."] These formulations inherently require an alkalinity source to facilitate the perhydrolysis reaction, which can be provided by the percarbonate itself or by additional builders, as is common in bleach compositions.
• Motivation to Modify: The patent goes on to highlight significant problems with TAED in these solid bleach formulations: "TAED has low water solubility, especially at the cooler water temperature bleaching cycles that are less damaging to fabrics. This is a major drawback... Undissolved TAED in cool temperature water is less unavailable as an acetyl precursor for the dissolved source of hydrogen peroxide and can even deposit on fabrics, necessitating a separate rinse step to remove it." [cite: "TAED has low water solubility, especially at the cooler water temperature bleaching cycles that are less damaging to fabrics.", "Undissolved TAED in cool temperature water is less unavailable as an acetyl precursor for the dissolved source of hydrogen peroxide and can even deposit on fabrics, necessitating a separate rinse step to remove it."] The patent concludes that "Thus, there is a need for a solid, peroxygen bleach that overcomes the deficiencies of the TAED-containing bleaches." [cite: "Thus, there is a need for a solid, peroxygen bleach that overcomes the deficiencies of the TAED-containing bleaches."] A PHOSITA in the field of laundry bleach formulation would be strongly motivated to address these clearly identified deficiencies.
• Substitution with Triacetin: Triacetin is a known liquid acetyl precursor with excellent water solubility. Substituting the problematic solid TAED with a more soluble liquid acetyl precursor like triacetin in a solid bleach formulation would be an obvious design choice for a PHOSITA aiming to improve cold-water performance and prevent fabric deposition. The maintenance of the solid hydrogen peroxide source (e.g., sodium percarbonate, explicitly mentioned in the background) and a solid alkalinity source (common in bleaches and essential for perhydrolysis) would also be obvious.
• Achieving "Freely-Flowable Solid": Incorporating a liquid component (triacetin) into a solid mixture while maintaining a "freely-flowable" characteristic is a routine formulation challenge in chemistry. The patent itself demonstrates that "the triacetin could be blended with up to 8.45 g of the triacetin to form a freely-flowable solid composition, without becoming a sticky, non-flowable product which would not pour easily or would become a solid mass upon storage inside a container." [cite: "the triacetin could be blended with up to 8.45 g of the triacetin to form a freely-flowable solid composition, without becoming a sticky, non-flowable product which would not pour easily or would become a solid mass upon storage inside a container."] This indicates that achieving such a physical form is a solvable problem through routine formulation techniques and optimization of component ratios, which would be predictable to a PHOSITA. The selection of various water-soluble solid alkalinity sources (bicarbonate, carbonate, etc.) and their specific ranges would also fall within the ambit of routine experimentation for bleach formulations.
• Reasonable Expectation of Success: The underlying chemical reaction (perhydrolysis to form PAA) is well-understood. A PHOSITA would have a reasonable expectation that replacing a poorly soluble acetyl precursor with a highly soluble one, while maintaining the other necessary components (H2O2 source, alkalinity), would lead to improved PAA generation in solution, particularly in cold water, thus overcoming the known drawbacks. The specific composition ranges claimed would be derivable through routine optimization.

Therefore, Claim 16 would likely be rendered obvious by combining the known elements of solid laundry bleach formulations (as described in the patent's own background) with the recognized properties of triacetin as a soluble acetyl donor, motivated by the clearly stated need to overcome the deficiencies of TAED-based bleaches.

For US Patent 8546449, here's a detailed breakdown of its patent term adjustments, extensions, continuation applications, divisional applications, related family members, and projected expiration date:

Patent Term Adjustments (PTA) and Extensions (PTE)

• Patent Term Adjustments (PTA): US Patent 8546449 has an "Adjusted expiration" date of 2031-09-02. PTA is granted to compensate for delays by the USPTO during the prosecution of a patent application. The total PTA adds to the 20-year lifespan of the issued patent.
• Patent Term Extensions (PTE): There is no indication of Patent Term Extension (PTE) for US8546449 in the provided information. PTE is typically awarded to compensate for delays in obtaining regulatory approval for certain patented products, such as pharmaceuticals.

Continuation and Divisional Applications

US Patent 8546449 (which issued from application US13/065,553 filed on March 24, 2011) is part of a patent family that includes continuation-in-part and divisional applications.

Continuation Applications:

• US10912321B2 (US Patent No. 10,912,321): This patent, titled "Methods of using peracetic acid to treat poultry in a chill tank during processing," is a continuation-in-part of and claims priority to the application (US13/065,553) that led to US8546449. It was filed on August 16, 2011, and issued on February 9, 2021.

Divisional Applications:

The litigation record for IPR2025-01472 explicitly mentions that the district court case against Clean Chemistry, Inc. alleges infringement of US8546449, as well as three divisional patents:

• US9737072 (U.S. Patent No. 9,737,072): This is identified as a divisional patent of US8546449. Its priority date is March 7, 2016.
• US9730443 (U.S. Patent No. 9,730,443): This is identified as a divisional patent of US8546449. Its priority date is March 7, 2016.
• US9363997 (U.S. Patent No. 9,363,997): This is identified as a divisional patent of US8546449. Its priority date is April 8, 2015.

Related Family Members

In addition to the continuation-in-part and divisional applications mentioned above, other related patent family members include:

• US20120245228A1: This is a publication of the application that led to US8546449, published on September 27, 2012.
• US9370180B2 (U.S. Patent No. 9,370,180): This patent, titled "Methods and compositions for the generation of peracetic acid on site at the point-of-use," was filed on September 5, 2013, and issued on June 21, 2016. It is broadly related and shares the same title.
• US10004230B2 (U.S. Patent No. 10,004,230): This patent is also listed as one of the patents issued subsequently to US8546449 within Enviro Tech's portfolio.
• US20170311595A1: This application, titled "Methods and Compositions for the Generation of Peracetic Acid On Site at the Point-of-Use," was filed on July 18, 2017, and published on November 2, 2017.

Projected Expiration Date

The "Adjusted expiration" date for US8546449 is 2031-09-02. This date includes any Patent Term Adjustment (PTA) granted to the patent. Utility patents generally have a term of 20 years from their earliest filing date, which can be extended by PTA for USPTO administrative delays. The original filing date for the application that led to US8546449 was March 24, 2011.