Soft Creped Tissue Web with Cationic Polymer Bonding
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Solution Overview
Problem
Existing paper products face a challenge in achieving a balance between softness and strength, as methods to increase strength often compromise fiber bonding, leading to issues like lint and sloughing, and excessive use of debonders is undesirable.
Innovation Solution
A creped tissue web with a creping composition comprising a mixture of (poly)ethylene oxide, polyvinyl alcohol, carboxymethylcellulose, or hydroxypropyl cellulose, applied at high add-on levels to maintain strength while enhancing softness, using a creping composition that includes cationic polymers like cationic starch to improve fiber bonding without relying heavily on chemical debonders.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If chemical debonders are used to increase softness, then softness is improved, but fiber bonding is decreased leading to lint and sloughing
Solution Approach 1:
The patent applies chemical softening agents at controlled concentrations and uses specific creping parameters (temperature, pressure, blade angle) to achieve softness while maintaining fiber bonding strength. This resolves the contradiction by optimizing process parameters rather than using excessive debonders that would compromise strength.
Solution Approach 2:
The invention uses composite fiber structures combining different fiber types (wood fibers, hardwood fibers, and synthetic fibers) with varying bonding characteristics. This composite approach allows the tissue to achieve softness through fiber composition while maintaining overall structural integrity and resistance to linting and sloughing.
2Strength
If mechanical forces like creping or calendering are used to increase softness, then softness is improved, but hydrogen bonds between fibers are broken resulting in lint
Solution Approach 1:
The patent applies chemical softening agents to the tissue web before the creping process. This preliminary chemical softening reduces the mechanical forces needed during creping to achieve the desired softness, thereby preserving hydrogen bonds between fibers and preventing lint formation.
Solution Approach 2:
The invention optimizes creping parameters including dryer surface temperature, creping blade angle and pressure, and web tension to minimize mechanical fiber damage. By carefully controlling these parameters, the process achieves softness through controlled fiber separation while maintaining sufficient hydrogen bonding to prevent linting.
3Strength
If strength agents are added to increase strength, then strength is improved, but softness is adversely affected
Solution Approach 1:
The patent uses controlled amounts of strength agents combined with optimized creping parameters to achieve the desired balance. The chemical softening agents and mechanical creping work together to soften the tissue, while the strength agents provide necessary tensile strength without excessive stiffening.
Solution Approach 2:
The invention employs composite fiber structures where different fiber types contribute different properties. Wood fibers provide strength while hardwood fibers and synthetic fibers contribute to softness and bulk, allowing the tissue to achieve both strength and softness simultaneously without relying solely on chemical additives.
4Ease of operation
If excessive debonders are used to achieve softness, then softness is improved, but lint and sloughing increase substantially
Solution Approach 1:
The patent uses controlled concentrations of chemical softening agents combined with optimized creping parameters to achieve softness without excessive fiber separation. This parameter optimization reduces lint and sloughing while maintaining desired softness levels.
Solution Approach 2:
The creping process acts as an intermediary mechanism that transfers energy from the dryer surface to the tissue web in a controlled manner. This intermediary action softens the tissue through controlled fiber separation rather than direct mechanical force, reducing lint generation while achieving the desired softness.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The solution results in tissue products with improved softness and strength, characterized by low TS7 and TS750 values, maintaining sufficient geometric mean tensile strength and bulk characteristics, reducing lint and sloughing issues while minimizing debonder usage.
Implementation Method 1
a creping composition comprising a mixture of (poly)ethylene oxide, polyvinyl alcohol, carboxymethylcellulose, or hydroxypropyl cellulose
Implementation Method 2
using a creping composition that includes cationic polymers like cationic starch to improve fiber bonding
Data Source
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AI summary
The present disclosure is directed to creped tissue webs, and products produced therefrom. The creped tissue webs and tissue products made therefrom are soft and strong, such as having a TS7 value less than about 8.0. Moreover, the tissue of the present disclosure also preferably has low TS750 values such as less than about 7.0. Further, while webs prepared according to the present disclosure have low TS7, and in certain embodiments low TS750 values, they are also strong enough to withstand use.