Multi-Ply Tissue With Latex Creping for Low Stiffness
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Solution Overview
Problem
Existing tissue products struggle to balance properties such as bulk, softness, durability, and drapability, particularly in achieving low modulus in both machine and cross-machine directions without compromising stiffness.
Innovation Solution
Manufacturing tissue products through a creped, through-air drying process with latex creping compositions on outer surfaces, reducing fiber-fiber bonding to lower geometric mean slope and modulus, while maintaining or enhancing tensile energy absorption and bulk.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of moving object
If through-air drying process is used to maintain bulk and softness, then bulk is improved, but modulus and stiffness increase
Solution Approach 1:
The patent applies parameter changes by modifying the drying process parameters - specifically using a two-stage through-air drying process with controlled air velocity and temperature in different zones. The first stage uses high air velocity to remove free water while the second stage uses lower velocity to remove bound water, thereby controlling fiber bonding and achieving desired bulk and modulus properties simultaneously
Solution Approach 2:
The patent implements dynamics by using a moving web through-air drying system where the tissue web continuously moves through the drying chamber. The air velocity, temperature, and web speed are dynamically adjusted during the drying process to control fiber-fiber bonding and achieve the target bulk and modulus characteristics
2Ease of operation
If surface texture is increased to improve wiping utility, then wiping utility is improved, but product complexity increases
Solution Approach 1:
The patent applies curvature principles by forming the tissue web into a cylindrical shape around a drying drum during the through-air drying process. This curved geometry naturally creates surface texture and three-dimensional structure that enhances wiping utility without requiring additional complex processing steps or equipment
3Reliability
If MD stretch and modulus are decreased to improve durability, then durability is improved, but tensile strength is reduced
Solution Approach 1:
The patent applies local quality by creating different structural characteristics in different regions of the tissue web. The through-air drying process produces varying fiber bonding densities and web structures in machine direction versus cross-machine direction, allowing the web to have localized properties that provide both stretch/durability and adequate tensile strength where needed
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 process results in tissue products with low stiffness index, high drapability, and durability, achieving geometric mean tensile energy absorption greater than 15.0 g·cm/cm² and bulk greater than 10.0 cc/g, with geometric mean tensile strength less than 2,500 g/3″.
Implementation Method 1
The wet molded web is typically dried by passing heated air through both the fabric and the wet web as it is transported over a cylindrical dryer
Implementation Method 2
The wet-laid web is molded to the through-air drying fabric and is supported by the fabric until it is at least almost completely dry
Implementation Method 3
Manufacturing tissue products through a creped, through-air drying process with latex creping compositions on outer surfaces
Data Source
AI summary
Disclosed are multi-ply tissue products, particularly creped and through-air dried tissue products, having cloth like properties, such as good drapability and durability. For example, the products generally comprise two plies and have a geometric mean slope (GM Slope) less than about 10.0 kg and a geometric mean tensile energy absorption (GM TEA) of about 15 g·cm/cm2 or greater. In certain instances, the tissue products also have a low degree of stiffness, such as a Stiffness Index less than about 5.00. The tissue products may be prepared from webs manufactured by a print-crepe process that deposits a latex polymer on at least one of the outer surfaces of the tissue web.