Obviousness

Obviousness Analysis under 35 U.S.C. § 103 for US Patent 8772416

This analysis considers whether the claims of US Patent 8772416, "Ink compositions containing isosorbide-capped amide gellant," would have been obvious to a person having ordinary skill in the art (PHOSITA) as of the patent's filing date (April 9, 2012), based on the prior art identified in the preceding "Prior Art" section.

A PHOSITA in the field of curable solid ink compositions and gellant chemistry would possess knowledge of polymer chemistry, synthesis of amide and ester compounds, the various components of curable inks (waxes, monomers, photoinitiators, gellants), and desired ink performance characteristics (viscosity, jetting temperature, cure speed, hardness, shrinkage). They would also be aware of industry trends, such as the increasing demand for bio-renewable materials.

The core distinguishing feature of US8772416's gellant (Claims 1-10) is the use of isosorbide as the end-capping group for an ester-terminated polyamide resin. While the prior art teaches various end-capped amide gellants for different applications, none explicitly disclose isosorbide as the end-capping agent. The obviousness argument will therefore center on whether a PHOSITA would have been motivated to substitute conventional end-caps with isosorbide, with a reasonable expectation of success.

Combinations of Prior Art for Obviousness

Combination 1: U.S. Patent No. 5,783,657 (Pavlin et al.) or U.S. Patent No. 6,111,055 (Berger et al.) in view of general knowledge regarding bio-renewable materials and the advantageous reactivity of isosorbide.

• Prior Art Teachings:
  • US5783657 (Pavlin et al.) and US6111055 (Berger et al.) (a continuation-in-part of Pavlin et al.) disclose ester-terminated polyamide gelling agents. These patents teach the fundamental structure and synthesis of polyamide gellants that are end-capped with ester groups derived from alcohols (specifically C12-C22 alkyl and alkenyl groups).
• Motivation to Combine/Modify:
  • Desire for Bio-Renewable Content: By 2012, there was a well-established and growing trend in various industries, including materials science and chemistry, to develop and utilize bio-renewable resources to reduce reliance on petroleum-based products. Isosorbide was a known bio-based diol molecule derived from sorbitol (from corn) and would be a prime candidate for incorporating bio-renewable content into chemical compounds. The patent itself identifies isosorbide as a "low-cost bio-renewable content substitute to conventional gellants, such as those end-capped with alcohols."
  • Improved Synthesis and Controlled Reactivity: The patent explicitly highlights isosorbide's "unique V-shaped structure" and "different reactivity (endo and exo-)" of its two hydroxyl groups. It notes that this allows for "only one functional group [to] participate[] in the esterification process under mild DCC coupling conditions," which can prevent "undesired side products, such as dimers or oligomers" that might occur with other diols. A PHOSITA, seeking to optimize the synthesis of ester-terminated polyamide gellants (as taught by Pavlin/Berger) for better purity or yield, would be motivated to explore diols offering such controlled reactivity. Isosorbide's known selective functionalization properties would make it an attractive choice for replacing less specific alcohol end-cappers.
• Reasonable Expectation of Success: Given that isosorbide is a known diol and its chemical reactivity (including differential reactivity of its hydroxyl groups) would be understood by a PHOSITA, there would be a reasonable expectation of successfully synthesizing an isosorbide-capped ester-terminated polyamide gellant using established esterification techniques (e.g., DCC coupling as described in the patent).
• Obviousness Finding: This combination would render the specific isosorbide end-capped amide gellant compounds claimed in Claims 1-10 of US8772416 obvious. A PHOSITA, motivated by the desire for bio-renewable materials and the known synthetic advantages of isosorbide, would have found it obvious to substitute the conventional alcohol end-caps of the Pavlin/Berger gellants with isosorbide.

Combination 2: U.S. Patent No. 7,296,614 (Toma et al.) or U.S. Patent No. 7,279,584 (Odell et al.) in view of U.S. Patent No. 5,783,657 (Pavlin et al.) or U.S. Patent No. 6,111,055 (Berger et al.), further in view of general knowledge regarding bio-renewable materials and the advantageous reactivity of isosorbide.

• Prior Art Teachings:
  • US7296614 (Toma et al.) discloses curable amide gellants where the end caps have at least one ethylenically unsaturated group, used in phase change ink compositions to increase mechanical robustness after curing.
  • US7279584 (Odell et al.) discloses photoinitiating compounds with phase change properties and gellant affinity, where the end caps have at least one photoinitiating group, integrated into solid ink compositions. (Note: The patent also mentions US7279587, which pertains to photoinitiating compounds in curable solid inks, supporting the general knowledge of such ink systems.)
  • These patents (Toma and Odell) establish the context of curable solid inks containing amide gellants, along with other standard components like monomers, curable waxes, and photoinitiators.
  • US5783657 (Pavlin et al.) and US6111055 (Berger et al.) teach the fundamental chemistry of ester-terminated polyamide gelling agents.
• Motivation to Combine/Modify:
  • A PHOSITA working on curable solid inks (as taught by Toma/Odell) would be continuously seeking to improve ink formulations. Given the established prior art on amide gellants (Toma/Odell, Pavlin/Berger), a motivation would exist to enhance these gellants by incorporating desirable properties such as bio-renewable content and improved synthesis control.
  • The explicit stated benefits in US8772416 for isosorbide-capped gellants, such as being a "low-cost bio-renewable content substitute to conventional gellants, such as those end-capped with alcohols" with "comparable phase-change properties to those with aromatic end-caps," directly provide the motivation for a PHOSITA to explore this substitution. The unique controlled reactivity of isosorbide (as discussed in Combination 1) further solidifies this motivation for a chemist to achieve a cleaner, more efficient synthesis of the gellant.
• Reasonable Expectation of Success: As noted in Combination 1, a PHOSITA would have a reasonable expectation of successfully synthesizing the isosorbide-capped gellant. Once such a gellant is available, its incorporation into existing curable solid ink formulations (which routinely include curable waxes, monomers, and photoinitiators as taught by Toma and Odell) would be an expected and straightforward modification. The methods of jetting and curing such inks are also well-established in the prior art, as broadly referenced in US8772416 (e.g., U.S. Pat. No. 4,490,731 for solid ink jetting).
• Obviousness Finding: This combination would render the curable solid ink compositions (as claimed in Claims 11-17) and the methods of jet printing using such inks (as claimed in Claims 18-19) obvious. The specific isosorbide-capped gellant would be an obvious substitution into a known ink system with known components and processing steps, driven by the motivations to incorporate bio-renewable materials, improve synthesis, and potentially achieve comparable or improved performance.

Conclusion

While US8772416 highlights specific performance advantages like "faster phase change characteristics, excellent curing performance, increased hardness after curing, and low shrinkage characteristics", the underlying motivation for substituting conventional end-capping alcohols with isosorbide is strongly supported by the desire for bio-renewable content, cost-effectiveness, and the unique, advantageous reactivity of isosorbide in chemical synthesis. A PHOSITA, seeking these benefits, would have been motivated to combine the teachings of the prior art regarding polyamide gellants and curable ink compositions with the known properties and availability of isosorbide. The resulting gellant and ink compositions would therefore likely be considered obvious, as the claimed invention represents an obvious modification of existing technologies to achieve predictable results based on known chemical properties and industry trends.