Obviousness

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.