Obviousness

Obviousness Analysis of US Patent 11261566 under 35 U.S.C. § 103

This analysis identifies combinations of prior art references that would render the claims of US patent 11261566 obvious to a person having ordinary skill in the art (PHOSITA), along with the motivation for combining them. The analysis primarily focuses on Independent Claim 1, as outlined in the patent summary.

Independent Claim 1 of US11261566 specifies:

A clothing or a seam felt for a machine for producing a fibrous material, paper, board, tissue or pulp web, comprising:

• a base structure including a two-layer laminate structure formed of one or a plurality of flat-woven fabrics, said base structure having two end sides;
• said laminate structure having MD threads being monofilaments with a round cross section forming seam loops at said two end sides of said base structure, said seam loops interconnecting said two layers of said laminate structure, said seam loops having a diameter LD and said associated MD threads having a diameter MDYD;
• a seam interconnecting said end sides to make the clothing endless, said seam being formed by interengaging said seam loops of said two end sides and an insertion of an insertion element;
• said seam having a loop density of between 64% and 90%; and
• said diameter LD of said seam loops and said diameter MDYD of said associated MD threads having a ratio LD/MDYD of between 2.7 and 3.6. [cite: Claim 1]

Primary Prior Art Reference: EP 0 425 523 B1

The patent US11261566 itself describes EP 0 425 523 B1 as pertinent prior art. This reference teaches:

• The use of flat-woven webs to produce a clothing for a machine for producing a fibrous material web. [cite: Description, "EP 0 425 523 proposes the use of flat-woven webs."]
• These flat-woven webs are provided in twice the necessary length, and by folding the long-side ends over and placing them on each other, a two-layer laminate structure is produced. [cite: Description, "By folding the long-side ends over and placing them on each other, a two-layer laminate structure is produced."]
• By removing CD threads at the folds, seam loops are produced. [cite: Description, "By removing the CD threads at the folds, seam loops are produced."]
• The base structure can be made endless by interengaging the seam loops of both end sides and inserting an insertion element. [cite: Description, "By interengaging the seam loops of both end sides and inserting an insertion element, this base structure can be made endless."]
• In this configuration, the warp threads of the fabric become the MD threads of the clothing. [cite: Description, "As opposed to the structures woven in the round, here the warp threads of the fabric are the MD threads of the clothing."]

Thus, EP 0 425 523 B1 discloses most of the fundamental structural elements of Claim 1: a clothing with a two-layer laminate structure from flat-woven fabrics, MD threads forming seam loops at the ends, these loops connecting the layers, and the clothing being made endless by a seam formed by interengaging loops and an insertion element.

Missing Elements from EP 0 425 523 B1 in view of US11261566's description:

Based on the description of EP 0 425 523 B1 provided in US11261566, the following features of Claim 1 are not explicitly taught by this single reference:

1. MD threads being monofilaments with a round cross section.
2. The seam having a loop density of between 64% and 90%.
3. The LD/MDYD ratio being between 2.7 and 3.6.

Combination of Prior Art for Obviousness

Combination: EP 0 425 523 B1 in combination with general knowledge in the art regarding thread materials and geometry, and the recognized need for optimizing seam performance in papermaking fabrics.

Motivation for Combination: A person having ordinary skill in the art (PHOSITA) would be motivated to address the known disadvantages associated with the seam area in flat-woven fabrics, as articulated in the background of US11261566. These disadvantages include quality losses due to markings (e.g., from differing permeability) and the difficulty/lengthy process of manually drawing in the insertion element (pintle) to close the seam in wide machines. [cite: Description, "Firstly, these lie in the region of the seam. At the seam point, the properties differ from those of the remaining parts of the clothing. For example, the permeability for water and air is frequently higher here than in the rest of the clothing. As a result, it is possible for quality losses to occur as a result of markings in the paper.", Description, "The seam of a seam clothing is normally closed in the paper machine itself by drawing in an insertion element, also called a pintle. This drawing-in is done by hand and can be a lengthy process, particularly in wide machines."]

Addressing Missing Element 1: MD threads being monofilaments with a round cross section.

• Prior Art Teaching/General Knowledge: The patent itself indicates that the concept of MD threads as monofilaments with a round cross section is a known and advantageous embodiment. The description provides definitions for "diameter of a thread" for both "round threads" and "monofilaments which deviate from the round shape." [cite: Definitions, "diameter of a thread is used. In the case of round threads, this term is well-defined. For monofilaments which deviate from the round shape, or else for threads twisted from multiple monofilaments, the diameter of the thread should be understood to be the diameter of that circle which has the same area as the cross section of the thread or as the sum of the cross sections of the individual monofilaments."] Furthermore, it states, "In advantageous embodiments, provision can be made for the MD threads which are used in particular to form the seam loops to be embodied as monofilaments, in particular as monofilaments with a round cross section." [cite: Description, "In advantageous embodiments, provision can be made for the MD threads which are used in particular to form the seam loops to be embodied as monofilaments, in particular as monofilaments with a round cross section."]
• Motivation: A PHOSITA seeking to improve the durability, consistency, and structural integrity of seam loops in the flat-woven fabrics taught by EP 0 425 523 B1 would find it obvious to use monofilaments. Monofilaments are known in the art for their strength and resistance to abrasion compared to multifilament yarns. A round cross-section is a standard, robust, and easily manufactured shape for such filaments, contributing to smooth interaction with the insertion element and uniform loop formation. This would be a straightforward engineering choice to enhance the performance and longevity of the seam.

Addressing Missing Elements 2 & 3: Seam loop density of 64-90% and LD/MDYD ratio of 2.7-3.6.

• Prior Art Teaching/General Knowledge: The patent explicitly identifies the problems of "different dewatering" and "markings in the paper" due to differing properties (like permeability) in the seam area. [cite: Description, "At the seam point, the properties differ from those of the remaining parts of the clothing. For example, the permeability for water and air is frequently higher here than in the rest of the clothing. As a result, it is possible for quality losses to occur as a result of markings in the paper."] It also details the difficulty of pintle insertion if loops are too small and the risk of mechanical/hydraulic marking if loops are too large. [cite: Description, "The fact that the loop diameter does not become too small in relation to the MD thread diameter means that it is made easier to draw in the pintle.", Description, "However, the diameter or the LD/MDYD ratio must also not become too large. Excessively large loops can firstly lead to mechanical markings in the paper... On the other hand, large loops would also mean that the seam area itself becomes comparatively large. Since this seam area differs structurally from the remainder of the clothing and, in particular, also has a changed permeability for water and/or air, there is the danger in the seam area of hydraulic marking of the paper because of different dewatering. For this reason, it is desirable to keep the seam area as small as possible."] The patent further highlights that flat-woven clothings allow for higher MD thread density and thus higher loop density compared to round-woven fabrics. [cite: Description, "Since, as described above, in flat-woven clothings the weft threads correspond to the MD threads of the clothing, when flat-woven clothings are used a higher MD thread density, and therefore also a higher loop density, can be achieved."] It provides a calculation demonstrating how a 64% seam loop density is achieved using typical thread parameters. [cite: Definitions, "the seam loop density... In a fabric having an MD thread density of 64 yarns/100 mm, the seam area has twice the number, i.e. 128 yarns/100 mm, as a result of the MD threads of the two ends interengaging. If the number of threads is multiplied by the diameter, then the seam loop density (statement in percent) is obtained as a measure of the coverage of the seam area by MD threads. If, in the above example, monofilaments having a diameter of 0.5 mm are used, then the result is a seam loop density of 128 / 0.5 [mm] / 100 [mm] = 64%."].
• Motivation: A PHOSITA, starting with the flat-woven seam fabric of EP 0 425 523 B1 and aiming to solve the acknowledged problems of seam marking and seaming difficulty, would be motivated to optimize the geometric parameters of the seam loops.
  • To reduce permeability and hydraulic marking, the PHOSITA would be motivated to increase the seam loop density, exploring densities within the disclosed range (e.g., starting from a baseline like 64% and increasing it) given the benefits of flat-woven fabrics in achieving higher thread densities. [cite: Description, "Since the permeability of the seam tends to be higher than in the remainder of the clothing, the permeability of the seam can be reduced by a comparatively high seam loop density."]
  • To balance easy pintle insertion with reduced mechanical and hydraulic marking, the PHOSITA would be motivated to optimize the relationship between the seam loop diameter (LD) and the MD thread diameter (MDYD). The patent's explicit statement that "it is not the absolute loop diameter (in mm) but the relative value LD/MDYD that has to be used as the characteristic variable" [cite: Description, "In particular, the applicant has recognized the fact that it is not the absolute loop diameter (in mm) but the relative value LD/MDYD that has to be used as the characteristic variable."] reveals an insight into problem-solving, but the underlying motivation to explore this relationship to find an optimal range remains. Given the clear trade-offs, a PHOSITA would engage in routine experimentation and optimization to determine a suitable LD/MDYD ratio that achieves this balance, potentially arriving at values within the claimed range of 2.7 to 3.6. Other cited prior art, such as US20090090425A1 ("Flat woven full width on-machine-seamable fabric") or EP3196357A1 ("Base fabric for a papermaking felt having seam loops"), would likely inform a PHOSITA's understanding of desirable seam loop characteristics and practical ranges for dimensions in such fabrics, providing guidance for such routine optimization.

While the exact numerical ranges for loop density and LD/MDYD ratio are presented in US11261566 as an "optimum compromise" found through "trials by the applicant" [cite: Description, "Trials by the applicant have shown that, given the LD/MDYD ratios according to the invention, the seam produced is optimal from several points of view.", Description, "The LD/MDYD range according to the invention of between 2.5 and 4, in particular between 2.7 and 3.6, has proven to be the optimum compromise here."], which suggests non-obvious experimentation, the clear articulation of the problem and the conflicting design parameters in the patent's background would motivate a PHOSITA to perform such routine optimization on the flat-woven seam fabrics of EP 0 425 523 B1 using known materials like monofilaments to arrive at improved performance within these defined parameters. Therefore, the combination of EP 0 425 523 B1 with the general knowledge of thread characteristics and the motivation to optimize seam properties to resolve known issues would render Claim 1 obvious.