Sanitary Tissue Roll Density Gradient to Reduce Curling
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional sanitary thin paper rolls tend to curl when unrolled and cut, making it difficult to use the cut pieces effectively.
Innovation Solution
The sanitary thin paper roll is designed with a basis weight and density gradient, where the outermost face has a smaller basis weight and higher density than the innermost face, and lines of perforation are formed at predetermined intervals to facilitate easy cutting and reduce curling.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If conventional sanitary thin paper rolls are continuously unrolled and cut by a required length, then the user can obtain cut pieces of paper, but the cut pieces tend to curl and are hard to flatten and use
Solution Approach 1:
The patent applies local quality by creating a density gradient within the paper sheet structure. The paper sheet has different densities at different positions: the first region (inner layer) has a first density, while the second region (outer layer) has a second density that is 0.8 to 1.2 times the first density. This localized density variation compensates for the curling tendency during cutting and improves flattenability without affecting the overall paper quality.
Solution Approach 2:
The patent employs parameter changes by systematically adjusting the density parameter across different regions of the paper sheet. The density ratio between the second region and first region is controlled within a specific range (0.8 to 1.2), which optimizes the balance between reducing roll paper curl and maintaining other paper properties. This controlled parameter variation enables the paper to flatten easily after cutting while preserving its functional characteristics.
2Ease of manufacture
If the paper sheet has uniform density throughout, then the manufacturing process is simple, but the cut pieces curl excessively and are difficult to use
Solution Approach 1:
The patent implements local quality by introducing a density gradient within the paper sheet, where the second region (outer layer) has a density 0.8 to 1.2 times that of the first region (inner layer). This localized density variation is achieved through controlled manufacturing processes that modify fiber distribution or bonding characteristics in specific regions, thereby reducing curling without significantly complicating the overall manufacturing approach.
Solution Approach 2:
The patent effectively creates a composite structure within the single paper sheet by combining regions of different densities. The paper sheet comprises a first region with a first density and a second region with a second density (0.8 to 1.2 times the first density). This internal composite structure allows different parts of the same paper to have optimized properties for their specific functions, reducing curl while maintaining manufacturability.
3Shape
If the outer layer paper is made denser, then the roll paper curl is reduced and flattenability is improved, but the oil penetration resistance may be affected
Solution Approach 1:
The patent applies parameter changes by controlling the density ratio between the second region and first region within a specific range (0.8 to 1.2 times). This controlled parameter adjustment optimizes the balance between reducing roll paper curl and maintaining oil penetration resistance. The density increase in the outer region is sufficient to reduce curling but limited enough to preserve the paper's ability to absorb and wipe oil effectively.
Data Source
Figure 1~2
Figure 3
Figure 4(A)~4(D)
AI summary
[PROBLEMS] To reduce the occurrence of a permanent set of winding of a sanitary tissue paper roll. [MEANS FOR SOLVING PROBLEMS] A roll is constituted by two or more plies of sheet. The basis weight of a sanitary tissue paper located on the outermost face of the roll is smaller than the basis weight of the sanitary tissue paper located on the innermost face of the roll, and the density of the sanitary tissue paper located on the outermost face of the roll is larger than the density of the sanitary tissue paper located on the innermost face of the roll.