Interlinked Stitch-Pair Knit Fabric for Thin Roofing Membranes
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Solution Overview
Problem
Existing roofing membranes with thicker fabric layers require calendaring to achieve desired thickness, which is a costly manufacturing step, and exhibit higher elongations that may not be suitable for all applications.
Innovation Solution
A knit fabric design featuring pairs of stitch yarns with interlinked two-bar stitch patterns, a warp yarn set with in-lay warp yarns, and a weft yarn set, allowing for a thinner construction without the need for calendaring, with specific stitch patterns and yarn configurations that reduce thickness and elongation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a thicker fabric layer is used in roofing membranes, then the membrane has higher strength and durability, but the membrane requires calendaring to achieve desired thickness and exhibits higher elongation
Solution Approach 1:
The fabric is segmented into multiple independent stitch yarn pairs, each forming discrete interlinked loops. This segmentation allows the fabric to achieve necessary strength through distributed stress points while maintaining thinness, as each stitch pair independently contributes to structural integrity without requiring excessive material thickness
Solution Approach 2:
The invention uses a thin film approach by constructing the fabric with multiple stitch yarn pairs that create strength through their interlinked configuration rather than through material thickness. The fabric achieves the desired thin profile (0.2-0.5mm) while maintaining structural integrity through the engineered stitch pattern
2Strength
If a thicker fabric layer is used in roofing membranes, then the membrane has higher strength, but calendaring is required which increases manufacturing cost
Solution Approach 1:
The fabric structure is divided into multiple independent stitch yarn pairs that can be knitted in a standardized repeating pattern. This segmentation enables consistent production of thin, strong fabric without requiring post-manufacturing calendaring processes, simplifying the manufacturing workflow while maintaining structural strength
Solution Approach 2:
The invention changes the fundamental parameter of fabric construction from thickness-based strength to configuration-based strength. By altering the stitch pattern design (two-bar pattern with interlinked yarns) rather than increasing material thickness, the fabric achieves strength without requiring calendaring, thereby simplifying manufacturing
3Ease of manufacture
If a thinner fabric layer is used in roofing membranes, then calendaring can be eliminated reducing manufacturing cost, but the fabric must maintain sufficient strength
Solution Approach 1:
The invention successfully implements a thin film fabric (0.2-0.5mm) that eliminates the need for calendaring while maintaining sufficient strength for roofing applications. The strength is achieved through the engineered interlinked stitch pattern rather than material thickness
Solution Approach 2:
The fabric uses a composite yarn structure within each stitch pair, combining different yarn types (e.g., UV-resistant outer yarns with reinforcement inner yarns) to achieve high strength in a thin configuration. This composite approach allows the thin fabric to meet strength requirements without calendaring
4Strength
If traditional stitch patterns are used, then the fabric has adequate strength, but the fabric thickness is too great for roofing membrane applications
Solution Approach 1:
The traditional continuous stitch pattern is segmented into discrete, repeating two-bar units with controlled spacing. This segmentation creates a lighter, thinner fabric structure where each segment contributes to overall strength without requiring dense, thick material coverage
Solution Approach 2:
The stitch pattern applies local quality enhancement by concentrating reinforcement at critical interlink points between yarn pairs while maintaining lighter construction in other areas. This localized strengthening allows thinness overall while preserving necessary strength characteristics
Data Source
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AI summary
A knit fabric containing a stitch yarn set containing pairs of stitch yarns, a warp yarn set containing in-lay warp yarns, and a weft yarn set containing weft inserted yarns. Each pair of stitch yarns comprises a first stitch yarn and a second stitch yarn, where the first stitch yarn has a two bar first stitch pattern comprising repeating pattern of at least one tricot stitch optionally followed by at least one pillar stitch and the second stitch pattern comprises a mirror image to the first stitch pattern. The first stitch yarn and the second stitch yarn within each pair of stitch yarns are interlinked together, but the first stitch yarn and second stitch yarn of one pair of stitch yarns are not interlinked with first stitch yarn and second stitch yarn of adjacent pairs of stitch yarns.