Soft tissue comprising synthetic fibers
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Solution Overview
Problem
The challenge in tissue paper production is to balance strength and softness while facing economic and environmental pressures on Northern Softwood Kraft fibers, which are ideal for durability and softness, but are under supply pressure, and Southern Softwood Kraft fibers are too coarse for soft tissue products.
Innovation Solution
Substituting the long, low-coarseness cellulosic fiber fraction with a blend of long, high-coarseness cellulosic fibers and synthetic fibers, which maintains or improves tissue product strength and softness without degrading other properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If long, low-coarseness cellulosic fibers (NSWK) are used to provide strength and softness, then tissue product durability and softness are improved, but supply availability and cost are worsened due to economic and environmental pressures
Solution Approach 1:
The patent substitutes expensive, scarce NSWK fibers with more abundant, cost-effective fiber alternatives including SSWK fibers and recycled fibers. While individual alternative fibers may have shorter service life or lower performance, the blend achieves acceptable durability at lower cost and with greater supply availability.
Solution Approach 2:
The patent creates a composite fiber furnish by blending multiple fiber types (SSWK, hardwood kraft, recycled fibers) in specific proportions. This composite approach allows the tissue product to achieve the desired balance of strength, softness, and cost-effectiveness that cannot be obtained with single fiber types alone.
2Quantity of substance
If SSWK fibers are used as alternatives to NSWK fibers, then supply availability is improved, but tissue product softness is worsened due to higher coarseness
Solution Approach 1:
The patent applies local quality by assigning different fiber types to different functional roles within the tissue structure. SSWK fibers (coarser) provide structural framework and bulk, while hardwood kraft fibers and recycled fibers (softer) are distributed to provide surface softness and comfort. This spatial differentiation of fiber functions allows the use of coarser fibers without sacrificing overall product softness.
Solution Approach 2:
The patent changes the compositional parameters of the fiber furnish by specifying precise proportions of different fiber types (e.g., SSWK fibers at least 10% by weight, hardwood kraft fibers at least 40% by weight). By adjusting these compositional parameters, the patent optimizes the balance between using abundant SSWK fibers and maintaining acceptable softness through the diluting effect of softer hardwood and recycled fibers.
Data Source
AI summary
The present application provides a tissue product comprising at least about 10 weight percent high coarseness fibers, from about 1.0 to about 10 weight percent synthetic fibers and less than about 10 weight percent long, low-coarseness cellulosic fibers. The high coarseness fibers may be cellulosic fibers having an average fiber length greater than about 2.0 mm and a coarseness greater than 17 mg/100 m, such as Southern softwood kraft pulp fibers (SSWK) derived from a pine in the Pinus subgenus, and the synthetic fiber is a non-cellulosic, thermoplastic fiber such as non-fibrillated polyethylene terephthalate (PET) fibers. In certain embodiments the tissue products may be substantially free from long, low coarseness cellulosic fibers, yet provide satisfactory strength, such as a geometric mean tensile from about 500 to about 1,200 g/3″, and softness, such as a TS7 less than about 11.0.