US 9363997

US Patent 9363997 Summary:

• 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: April 8, 2015
• Issue Date: June 14, 2016
• Abstract: The patent discloses methods for generating non-equilibrium solutions of peroxyacetic acid (PAA) on-site. These methods involve introducing triacetin and aqueous hydrogen peroxide to water, mixing them, and then adding an aqueous source of an alkali metal or earth alkali metal hydroxide. Triacetin is rapidly and highly converted into peracetic acid, resulting in solutions with a high PAA concentration.

Plain-Language Overview of Independent Claims:

• Claim 1 (Method for On-Site PAA Generation): This claim describes a method for continuously or intermittently creating a peracetic acid (PAA) solution at the location where it will be used (point-of-use) for disinfection or sanitation. The method involves:

  1. Providing water at the point-of-use.
  2. Providing a pre-mixed solution containing hydrogen peroxide and an acetyl precursor (a substance that reacts to form the acetyl group), which is soluble in aqueous hydrogen peroxide.
  3. Introducing this hydrogen peroxide-acetyl precursor solution to the water to form a mixture.
  4. Adding an aqueous source of an alkali metal or earth alkali metal hydroxide to the mixture to form a reaction medium, where hydrogen peroxide reacts with the acetyl precursor to produce PAA.

• Claim 17 (Liquid Composition for PAA Generation): This claim covers a liquid composition designed to produce a non-equilibrium solution of peracetic acid at the point-of-use. The composition includes:

  1. Aqueous hydrogen peroxide.
  2. A liquid acetyl precursor that can dissolve in aqueous hydrogen peroxide.
  3. A small amount of peracetic acid (trace amount).
  4. Water.

• Claim 21 (Solid Peroxygen Composition for Bleaching/Stain Removal): This claim describes a free-flowing, solid composition containing peroxygen for use in laundry bleaching and stain removal. It consists of:

  1. A liquid acetyl precursor.
  2. A water-soluble solid source of hydrogen peroxide.
  3. A water-soluble solid source of alkalinity.

• Claim 26 (Method of Preparing a Hydrogen Peroxide-Acetyl Precursor Solution): This claim outlines a method for preparing the hydrogen peroxide-acetyl precursor solution mentioned in Claim 17. The method involves:

  1. Introducing a liquid acetyl precursor that is soluble in aqueous hydrogen peroxide to a solution of aqueous hydrogen peroxide.
  2. Allowing these components to mix to form the hydrogen peroxide-acetyl precursor solution.

• Claim 29 (Method of Preparing a Solid Peroxygen Composition): This claim details a method for preparing the free-flowing, solid peroxygen composition described in Claim 21. The method involves:

  1. Blending a liquid acetyl precursor, a water-soluble solid source of hydrogen peroxide, and a water-soluble solid source of alkalinity to create the solid composition.

Litigation/Legal Status (as of April 26, 2026):

US Patent 9363997 is currently active and is involved in litigation.

• It is asserted in a district court lawsuit, Enviro Tech Chemical Services, Inc. v. Clean Chemistry, Inc., Case No. 1:24-cv-1313, filed in the Western District of Texas on October 29, 2024. This case also involves related patents US 8,546,449, US 9,737,072, and US 9,730,443. A trial in this District Court Case is scheduled for the week of December 28, 2026.
• An Inter Partes Review (IPR2025-01471) challenging claims 1-14 of US 9363997 was filed by Clean Chemistry, Inc. on September 2, 2025, before the Patent Trial and Appeal Board (PTAB). This IPR is currently marked as "Not Instituted - Procedural."
• Separately, a related patent (US 10,912,321), which is a continuation-in-part of a patent in the same family, was the subject of an appeal to the Federal Circuit (Enviro Tech Chem. Servs., Inc. v. Safe Foods Corp., Appeal No. 2024-2160). On May 4, 2026, the Federal Circuit affirmed a district court ruling that certain claims of US 10,912,321 were invalid as indefinite, specifically concerning the term "about" in relation to a claimed pH range. While this ruling is not directly on US 9363997, it indicates ongoing challenges to Enviro Tech Chemical Services' patent portfolio in the peracetic acid field.

As a patent attorney, I have investigated litigation involving US Patent 9363997. Here's what I've found:

Known Litigation Involving US Patent 9363997:

1. District Court Case:

   • Plaintiff(s): Enviro Tech Chemical Services, Inc.
   • Defendant(s): Clean Chemistry, Inc.
   • Jurisdiction: U.S. District Court for the Western District of Texas
   • Case Number: 1:24-cv-01313
   • Filing Date: Not explicitly stated in the provided snippets, but the case is mentioned in a petition for Inter Partes Review filed on September 2, 2025, indicating it was filed before this date.
   • Outcome/Current Status: The '997 patent was asserted in this litigation. The case is ongoing.

2. PTAB Case (Inter Partes Review):

   • Plaintiff(s) (Petitioner): Clean Chemistry, Inc. ("Clean Chem")
   • Defendant(s) (Patent Owner): Enviro Tech Chemical Services, Inc. (Implied, as they are the assignee of the patent)
   • Jurisdiction: Patent Trial and Appeal Board (PTAB)
   • Case Number: IPR2025-01471
   • Filing Date: September 2, 2025
   • Outcome/Current Status: The petition requests an Inter Partes Review of claims 1-14 of US Patent 9363997. The status is "Not Instituted - Procedural."

It's important to note that the patent (US9363997B2) is currently listed as "Active".

Proceedings overview

One AIA trial proceeding has been filed against US patent 9363997. This proceeding resulted in a discretionary denial of institution, meaning no claims were challenged on the merits and the patent's claims remain untested by PTAB review. This posture indicates that the patent has not yet faced a full challenge at the PTAB, but a prior attempt by Clean Chemistry, Inc. was denied institution.

IPR2025-01471 — Clean Chemistry, Inc. v. Enviro Tech Chemical Services Inc

• Type: Inter Partes Review
• Filed: 2025-09-02
• Status: Discretionary Denial — The PTAB declined to institute review based on a procedural ground, rather than on the merits of the prior art challenge.
• Judge panel: Not publicly available at this stage for a discretionary denial.
• Petition grounds: Details not specified in the provided data. Based on the "Discretionary Denial" status, the merits of the claims under § 102 / § 103 were likely not fully assessed in the decision to deny.
• Institution decision: Denied (Discretionary Denial) — The petition was denied institution on 2026-03-24. The reasoning for a discretionary denial often relates to factors like parallel district court litigation, timing of the petition, or efficiency concerns, rather than the petitioner's likelihood of success on the merits.
• Final Written Decision: Not issued, as institution was denied.
• Settlement / termination: Terminated via discretionary denial.
• Appeal: No Federal Circuit appeal related to the merits of the patent claims, as institution was denied.
• Defensive value: This proceeding indicates that Clean Chemistry, Inc. attempted to challenge the patent but was unsuccessful in getting the IPR instituted. While the claims were not upheld on the merits, they were also not invalidated. This means the patent's claims remain as granted by the USPTO, and a defendant would need to consider a new IPR petition if they wished to challenge the patent through this avenue.

Strategic summary

Currently, all claims of US9363997 remain SUSTAINED as they have not been subjected to a full merits review at the PTAB. The single IPR filed, IPR2025-01471, was denied institution on discretionary grounds, meaning the PTAB did not reach the merits of the prior art arguments against the patent's claims. Therefore, no claims have been canceled or deemed unpatentable by the PTAB.

The estoppel landscape for IPR2025-01471 is complex due to the discretionary denial. Generally, a petitioner is estopped under 35 U.S.C. § 315(e)(2) only if a Final Written Decision is issued. However, the Federal Circuit's Arthrex decision and subsequent guidance suggest that even certain types of discretionary denials (e.g., Sotera Wireless, Inc. v. Masimo Corp.) can lead to estoppel for the petitioner (Clean Chemistry, Inc.) regarding grounds that were raised or reasonably could have been raised. For other potential defendants, however, the full range of prior-art grounds under § 102 and § 103 remain available to challenge the patent's claims in a new IPR, as no merits decision was rendered in IPR2025-01471.

There is no clear pattern of aggressive PTAB appeals by the patent owner, nor has the same petitioner filed multiple IPRs on this patent based on the provided data. Unified Patents is listed as a petitioner in an IPR on this patent family (IPR2025-01471), suggesting potential defensive aggregation activity.

Recommended next steps

• Given the discretionary denial in IPR2025-01471, a potential defendant should review the specific reasoning for the denial in the institution decision to understand the procedural hurdles encountered by the previous petitioner, Clean Chemistry, Inc.
• As all claims of US9363997 remain unchallenged on the merits at the PTAB, a defendant facing assertion of this patent may consider filing a new IPR petition. The absence of a prior merits-based decision means that prior art grounds are still open for review by the PTAB for a new petitioner (assuming no privity with Clean Chemistry, Inc.).
• Monitor the patent's litigation history for any parallel district court proceedings that might influence future PTAB filings or vice-versa.

Inventors

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

No unusual patterns suggesting inventor departures prior to a portfolio fire-sale are immediately evident from the provided information.

Original assignee

Enviro Tech Chemical Services Inc. is the original assignee. Enviro Tech Chemical Services Inc. is a company that manufactures and supplies peracetic acid and other antimicrobial and disinfectant products, which would embody the claims of US9363997. The company appears to be currently operating.

Assignment timeline

The USPTO Assignment Center search for US Patent 9363997 (US9363997) shows no recorded assignments after issuance.

Timeline diagram

timeline
    title Ownership of US 9363997
    2011 : Priority date
    2015 : Application filed by Enviro Tech Chemical Services Inc
    2016 : Granted to Enviro Tech Chemical Services Inc

NPE / troll-pattern signals

1. Shell-entity transfer — not present (no recorded assignments)
2. Known asserter in the chain — not present (no recorded assignments)
3. Repeat correspondent across the chain — not present (no recorded assignments)
4. Cascading transfers — not present (no recorded assignments)
5. Pre-litigation transfer — unclear (While Google Patents indicates litigation, there are no recorded assignments to assess if a transfer occurred within 6 months of the first suit.)
6. Bankruptcy fire-sale — not present (no recorded assignments or indication of bankruptcy for the original assignee)
7. Privateering — unclear (no recorded assignments or public information to suggest this)
8. Defensive aggregator (anti-NPE) — not present (no recorded assignments to such entities)

Verdict

Insufficient data. There are no recorded assignments for US9363997 in the USPTO Assignment Center. Therefore, it is not possible to assess NPE/troll patterns based on assignment records. While Google Patents indicates litigation related to this patent, without assignment records, we cannot determine if the litigation is associated with an NPE.

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

U.S. Patent 9363997 (hereinafter '997 patent) describes methods and compositions for generating non-equilibrium peroxyacetic acid (PAA) solutions on-site at the point-of-use. The methods involve introducing triacetin and aqueous hydrogen peroxide to water, mixing, and then adding an aqueous source of an alkali metal or earth alkali metal hydroxide. Triacetin is rapidly converted into PAA with a high conversion rate, producing solutions with high levels of PAA. The patent also discloses a solid bleaching and stain removal composition.

Here's an analysis of the prior art cited in the '997 patent:

1. U.S. Pat. No. 7,012,154 (Agnihotri et al.)

• Full Citation: US7012154B2
• Publication/Filing Date: The '997 patent cites it as a U.S. Patent. The earliest priority date listed for the '997 patent is March 24, 2011, making US'154 a prior art reference.
• Brief Description: This patent discloses a system for the continuous, on-site, and on-demand production of aqueous peracetic acid. It involves feeding acetic acid, hydrogen peroxide, water, and sulfuric acid to a jacketed reactor, followed by a wiped-film distillation column to condense and isolate pure PAA before introducing it to receiving water.
• Potential Anticipation (35 U.S.C. § 102): US'154 describes a system for generating PAA on-site at the point-of-use. While it utilizes different reagents (acetic acid and sulfuric acid catalyst) and a more complex distillation process, it discloses the core concept of on-site PAA generation. It could potentially anticipate claims relating to the general method of generating non-equilibrium PAA on-site, particularly method claims that are broad enough to encompass various chemical pathways for PAA formation, if not sufficiently distinguished by the specific reagents and reaction conditions (e.g., using triacetin and alkali metal hydroxide).

2. U.S. Pat. No. 6,171,551 and 6,387,236 (Deemer et al.)

• Full Citation: US6171551B1 (no snippet provided, but mentioned in '997 patent text), US6387236B1 (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: The '997 patent cites these as U.S. Patents, thus preceding its priority date.
• Brief Description: These patents disclose electrolytic processes for producing PAA and other oxidants in the anode compartment of a cell divided by an ion-exchange membrane, using an aqueous solution of acetic acid or acetate salt. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): These references describe methods for generating non-equilibrium PAA on-site using an electrolytic approach. They could potentially anticipate claims in the '997 patent that broadly cover on-site PAA generation, especially those focusing on the "non-equilibrium" aspect, unless the '997 patent's claims are specifically limited to chemical (non-electrolytic) generation, or the specific reagents (triacetin, hydrogen peroxide, alkali) and their combination.

3. WIPO International Publication Nos. WO 2004/0245116 and WO 2008/140988, and U.S. Patent Application Publication No. 2009/0314652

• Full Citation: WO20040245116A1 (no snippet provided, but mentioned in '997 patent text), WO2008140988A1 (no snippet provided, but mentioned in '997 patent text), US20090314652A1 (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: These publications precede the priority date of the '997 patent.
• Brief Description: These references disclose cation membrane-divided electrolysis cells and gas diffusion electrodes to reduce oxygen gas to hydrogen peroxide under alkaline conditions. The hydrogen peroxide then reacts with acetic acid or an acetyl precursor to form PAA in the bulk solution, which is then directed to the acidic anode compartment for stabilization. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): Similar to the previous electrolytic references, these disclose on-site PAA generation. The inclusion of an "acetyl precursor" and the reaction with hydrogen peroxide to form PAA could potentially anticipate claims in the '997 patent that are broadly directed to using an acetyl precursor and hydrogen peroxide, especially if the claims do not sufficiently define the specific liquid acetyl precursor (triacetin) or the non-electrolytic process.

4. U.S. Pat. No. 5,122,538 (Bowman et al.)

• Full Citation: US5122538A (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: This patent precedes the priority date of the '997 patent.
• Brief Description: This patent describes generating non-equilibrium PAA at the point-of-use by substituting traditional mineral acid catalysts with sulfonic acid ion-exchange resins. A solution of acetic acid to hydrogen peroxide is passed through a resin column to produce PAA. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): This reference teaches on-site PAA generation using a chemical reaction, specifically employing an ion-exchange resin. It could potentially anticipate claims relating to the chemical generation of PAA on-site if the claims are not specifically limited to the use of an alkali metal or earth alkali metal hydroxide as the catalyst, or the specific liquid acetyl precursor (triacetin).

5. U.S. Pat. No. 3,432,546 (McManus)

• Full Citation: US3432546A (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: This patent precedes the priority date of the '997 patent.
• Brief Description: This patent discloses a process where hydrogen peroxide, acetic anhydride, and an ammonium hydroxide catalyst are metered to a tubular reactor to continuously produce a PAA solution. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): This reference teaches the continuous on-site production of PAA from hydrogen peroxide and an acetylating agent (acetic anhydride) using a basic catalyst (ammonium hydroxide). It could potentially anticipate claims that broadly cover the continuous generation of PAA from hydrogen peroxide and an acetyl precursor in the presence of an alkaline source, unless the claims specifically distinguish the use of triacetin and/or the type of alkali metal hydroxide, and the absence of ammonium hydroxide.

6. U.S. Patent Application Publication No. 2009/0043132 (Harvey et al.)

• Full Citation: US20090043132A1 (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: This publication precedes the priority date of the '997 patent.
• Brief Description: This process involves introducing hydrogen peroxide into a sidestream of water, followed by introducing acetic anhydride, to generate PAA in-situ. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): This reference describes on-site PAA generation using hydrogen peroxide and acetic anhydride. Similar to US3432546A, it could potentially anticipate claims broadly covering the on-site generation of PAA from hydrogen peroxide and an acetyl precursor if the claims do not sufficiently define the specific acetyl precursor (triacetin) or the alkaline conditions used in the '997 patent.

7. WIPO International Publication No. WO 01/46519 A1 (Bodmer et al.)

• Full Citation: WO0146519A1 (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: This publication precedes the priority date of the '997 patent.
• Brief Description: This process involves metering an aqueous solution of hydrogen peroxide into an agitated tank and co-metering a solid dry source of tetraacetylethylenediamine (TAED) from a hopper. This mixture is then fed to an in-line static mixer where aqueous sodium hydroxide is introduced, followed by coiled tubing in a cooling tank to contain the exothermic reaction. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): This reference is highly relevant as it describes on-site PAA generation using hydrogen peroxide, a solid acetyl precursor (TAED), and aqueous sodium hydroxide, with subsequent mixing and reaction time. It clearly demonstrates a system for generating PAA on-site using an alkali. This could potentially anticipate claims of the '997 patent that broadly cover the method of introducing hydrogen peroxide and an acetyl precursor to water, mixing, and then adding an aqueous source of alkali metal hydroxide to form PAA. The '997 patent distinguishes itself by using a liquid acetyl precursor (triacetin) and potentially highlighting the advantages of its specific composition and method over TAED-based systems (e.g., solubility, odor). Therefore, claims specifically reciting "liquid acetyl precursor" or "triacetin" would be important for distinguishing this prior art.

8. U.S. Pat. No. 7,651,724 (Gordon et al.)

• Full Citation: US7651724B2 (no snippet provided, but mentioned in '997 patent text)
• Publication/Filing Date: This patent precedes the priority date of the '997 patent.
• Brief Description: The '997 patent refers to this patent for its "modified DPD method" of analysis, a colorimetric method for measuring total chlorine in drinking water and wastewater, adapted for measuring PAA and hydrogen peroxide. [cite: 9363997B2]
• Potential Anticipation (35 U.S.C. § 102): This patent describes an analytical technique and not a method or composition for generating PAA. Therefore, it is unlikely to anticipate any claims of the '997 patent related to the methods or compositions for PAA generation, but it could be relevant for any claims regarding methods of measuring PAA or hydrogen peroxide if such claims were present and broadly drafted.

It is important to note that the provided patent text for US9363997B2 itself discusses the limitations and problems of these prior art methods, indicating that the '997 patent aims to overcome these issues with its specific compositions and methods. The distinctiveness of the '997 patent likely lies in the use of triacetin as a liquid acetyl precursor, its unexpected solubility in hydrogen peroxide, the specific alkaline conditions for rapid and high conversion to PAA, and the absence of certain undesirable byproducts or complex equipment.

Obviousness Analysis of US Patent 9363997 under 35 U.S.C. § 103

US Patent 9363997 (hereafter '997 patent) discloses methods and compositions for the generation of peracetic acid (PAA) on-site at the point-of-use. The invention primarily focuses on:

1. Liquid compositions comprising aqueous hydrogen peroxide and a liquid acetyl precursor (preferably triacetin) for generating non-equilibrium PAA solutions.
2. Methods for continuously or intermittently generating non-equilibrium PAA solutions on-site using these liquid compositions, by introducing them to water and then adding an aqueous source of alkali metal or earth alkali metal hydroxide.
3. Freely-flowable, solid peroxygen compositions for laundry bleaching and stain removal, comprising a liquid acetyl precursor (preferably triacetin), a water-soluble solid source of hydrogen peroxide, and a water-soluble solid source of alkalinity.

The obviousness analysis under 35 U.S.C. § 103 requires identifying prior art combinations that would make the claimed invention obvious to a person having ordinary skill in the art (PHOSITA) and articulating a motivation to combine those references.

1. Obviousness of Liquid Compositions and Methods for On-Site PAA Generation

The '997 patent's liquid compositions and methods for on-site PAA generation generally involve:

• A pre-mixture of aqueous hydrogen peroxide and a liquid acetyl precursor (specifically highlighting triacetin due to its unexpected solubility in hydrogen peroxide).
• Adding this pre-mixture (or its components separately) to water.
• Subsequently adding an aqueous source of alkali (e.g., NaOH) to rapidly generate PAA.

Prior Art Combination: WO 01/46519 A1 in view of the '997 patent's own discussion of TAED drawbacks and common chemical knowledge regarding triacetin and perhydrolysis.

Explanation of Obviousness:

WO 01/46519 A1 explicitly discloses a process for generating non-equilibrium solutions of PAA on-site at the point-of-use. This process meters an aqueous solution of hydrogen peroxide into an agitated tank and co-meters a solid dry source of tetraacetylethylenediamine (TAED) from a storage-hopper. Aqueous sodium hydroxide is then introduced downstream to an in-line static mixer, and the mixture is directed through coiled tubing in a cooling tank to manage the exothermic reaction. This reference clearly teaches the core concept of on-site PAA generation using hydrogen peroxide, an acetyl precursor, and an alkali (sodium hydroxide) for rapid reaction.

The '997 patent itself identifies significant disadvantages of the WO 01/46519 A1 system, including "difficulty of accurately metering a solid and a liquid simultaneously, and the high capital equipment cost of the metering system, electronic controllers, agitation tank, coiled tubular reactor, and the cooling system."

The '997 patent also discusses prior art concerning solid TAED-based laundry bleaches, noting issues such as "low water solubility, especially at the cooler water temperature bleaching cycles" and that "Undissolved TAED... can even deposit on fabrics." Furthermore, the '997 patent highlights the drawbacks of using acetic anhydride in other on-site PAA generation methods, describing it as "expensive, very corrosive, an irritant, and highly flammable."

Motivation to Combine: A person having ordinary skill in the art (PHOSITA) would be highly motivated to overcome the known problems associated with using solid TAED or corrosive acetic anhydride as acetyl precursors in on-site PAA generation systems. Specifically, they would seek a liquid, safer, and more easily metered acetyl precursor to simplify the system described in WO 01/46519 A1 and address the solubility/metering challenges.

Triacetin (glycerol triacetate) is a well-known chemical compound with three acetyl groups capable of undergoing perhydrolysis. It is also known to be non-toxic, safe, non-corrosive, non-irritating, non-flammable, and Generally Recognized as Safe (GRAS) by the FDA, as stated in the '997 patent. Faced with the explicit problems of solid TAED metering (WO 01/46519 A1) and its solubility (as detailed in the '997 patent's background on laundry bleaches), a PHOSITA would naturally consider alternative acetyl precursors. Triacetin, being a readily available liquid and known source of acetyl groups, would be an obvious candidate to investigate as a replacement for solid TAED or hazardous acetic anhydride.

Replacing the solid TAED in the WO 01/46519 A1 system with a liquid acetyl precursor like triacetin would directly address the "difficulty of accurately metering a solid and a liquid simultaneously" and could lead to a simpler and less capital-intensive system by eliminating the need for a screw feeder for solids. While the '997 patent claims "unexpectedly high solubility in 50% hydrogen peroxide" for triacetin, the initial motivation to try a liquid acetyl precursor to solve known metering and safety problems would render the general substitution obvious. The specific formulation details, such as optimal mole ratios and pH for rapid reaction, would be arrived at through routine experimentation by a PHOSITA once the decision to use triacetin in such a system was made.

Therefore, combining the on-site PAA generation system and alkaline perhydrolysis principle from WO 01/46519 A1 with the substitution of a liquid, safer, and more easily handled acetyl precursor like triacetin would have been obvious to a PHOSITA motivated to improve the prior art methods.

2. Obviousness of Solid Peroxygen Bleaching and Stain Removal Compositions

The '997 patent's solid compositions involve:

• A liquid acetyl precursor (preferably triacetin).
• A water-soluble solid source of hydrogen peroxide (e.g., sodium percarbonate).
• A water-soluble solid source of alkalinity.
• The composition produces PAA upon introduction to water.

Prior Art Combination: General knowledge of TAED-based solid peroxygen bleaches (as discussed within the '997 patent's background) in view of common chemical knowledge regarding triacetin.

Explanation of Obviousness:

The '997 patent itself extensively details the problems with existing "TAED-based laundry bleaches." It states that:

• "only two [of four acetyl groups] are known to be available for perhydrolysis, making TAED an expensive acetyl precursor on a weight basis." (Inefficiency)
• "TAED has low water solubility, especially at the cooler water temperature bleaching cycles that are less damaging to fabrics." (Poor performance at desired conditions)
• "Undissolved TAED... can even deposit on fabrics, necessitating a separate rinse step to remove it." (Undesirable side effect)
• "over time, when exposed to high humidity, solid TAED can react with the solid source of hydrogen peroxide and the free water to form PAA, as well as degrade the activity, making it less effective over time. Because the PAA is volatile, It imparts an undesirable pungent odor to the product." (Storage instability and odor problem)

Motivation to Combine: A PHOSITA in the field of laundry bleaching and stain removal would be highly motivated to replace TAED with an alternative acetyl precursor that overcomes these well-documented deficiencies. The desired characteristics for such an alternative would include higher efficiency (more available acetyl groups), better water solubility (especially in cool water), and improved storage stability (less PAA odor formation).

Triacetin, being a triglyceride of acetic acid, is a known chemical with three acetyl groups. As noted by the '997 patent, triacetin is also inexpensive, non-toxic, safe, non-corrosive, non-irritating, non-flammable, and GRAS by the FDA. Given these characteristics, a PHOSITA seeking to improve upon TAED would find triacetin to be a logical candidate for investigation. While triacetin is a liquid, the concept of incorporating a liquid component into a solid, freely-flowable particulate composition is a common practice in formulation chemistry, often achieved by absorption onto solid carriers or careful blending techniques. The '997 patent even teaches specific methods for blending a liquid acetyl precursor like triacetin into a solid peroxygen composition to maintain flowability.

The advantages claimed by the '997 patent for its solid triacetin composition—such as efficiently utilizing acetyl groups, high solubility in cool water, and absence of undesirable PAA odor upon storage—directly correspond to the identified problems of TAED. This strong problem-solution relationship indicates that a PHOSITA, motivated by the known drawbacks of TAED, would have a clear reason to modify existing TAED-based solid bleach formulations by substituting triacetin as the acetyl precursor. The development of a "freely-flowable" solid composition containing a liquid triacetin would be the result of routine formulation optimization.

Therefore, the substitution of triacetin for TAED in a solid peroxygen bleaching composition comprising a solid hydrogen peroxide source and a solid alkalinity source, driven by the desire to solve the known problems of TAED, would have been obvious to a PHOSITA.

For US Patent 9363997, here's a detailed breakdown of its patent term adjustments (PTA), patent term extensions (PTE), continuation/divisional applications, related family members, and projected expiration date:

Patent Term Adjustments (PTA)

Patent Term Adjustments (PTA) are granted to compensate for delays caused by the USPTO during the prosecution of a patent application. This can include delays in issuing a first Office Action, responding to applicant replies, or issuing the patent within certain timeframes. The USPTO calculates PTA at the time of patent issuance.

As of the current date (April 26, 2026), specific details on any PTA awarded to US Patent 9363997 are not available in the provided snippets. To determine the exact PTA, one would typically need to examine the Issue Notification Letter for the patent or use the USPTO's Patent Center.

Patent Term Extensions (PTE)

Patent Term Extensions (PTE) are available for patents claiming certain products (e.g., human drug products, medical devices, food additives) to restore patent term lost due to regulatory review periods by agencies like the FDA.

Based on the nature of the invention (methods and compositions for generating peracetic acid, primarily for disinfection and sanitization in various industries, including food and beverage processing), it's possible that the patent owner could apply for a PTE if the claimed invention or a product utilizing it required premarket regulatory approval. However, the provided information does not indicate that US Patent 9363997 has received any PTE. Applications for PTE are generally filed within 60 days of marketing approval of the product.

Continuation and Divisional Applications

US Patent 9363997 is part of a patent family with several related applications. It is explicitly stated that US 9363997 is a divisional application.

Here's the lineage provided in the patent text and search results:

• US 9363997 (filed April 8, 2015) is a divisional application of U.S. patent application Ser. No. 14/019,296, filed on September 5, 2013.
• U.S. patent application Ser. No. 14/019,296, in turn, is a divisional of prior application Ser. No. 13/065,553, filed on March 24, 2011, now U.S. Pat. No. 8,546,449.

This establishes a clear chain of priority:

• Grandparent Patent: U.S. Pat. No. 8,546,449 (filed March 24, 2011)
• Parent Application/Patent: U.S. Patent Application No. 14/019,296 (filed September 5, 2013), which issued as U.S. Patent No. 9,370,180.
• Current Patent: US 9363997 (filed April 8, 2015) is a divisional of US 14/019,296.

Related Family Members

The patent is part of a larger family of patents assigned to Enviro Tech Chemical Services Inc. In addition to the parent and grandparent identified above, other related family members mentioned include:

• US 9,737,072
• US 9,730,443
• US 10,004,230
• US 10,912,321
• U.S. Patent Application Publication No. 20150208652A1

These patents and applications all share the same priority date of March 24, 2011.

Projected Expiration Date

The general rule for utility patents filed on or after June 8, 1995, is that the term expires 20 years from the earliest effective filing date of the application, with any applicable Patent Term Adjustment (PTA) added. For continuation or divisional applications, the 20-year term is calculated from the filing date of the earliest application in the priority chain.

In this case, the earliest priority date for US 9363997 is March 24, 2011, derived from its grandparent U.S. Pat. No. 8,546,449.

Therefore, the nominal expiration date (before considering any PTA or PTE) would be 20 years from March 24, 2011.

Nominal Expiration Date: March 24, 2011 + 20 years = March 24, 2031.

Google Patents also lists an "Anticipated expiration" date of 2031-03-24, which aligns with this calculation.

As previously mentioned, specific PTA information for US 9363997 is not available in the provided snippets. Without this information, the definitive expiration date cannot be precisely calculated. However, assuming no PTA or PTE, the projected expiration date is March 24, 2031.