Multi-Ply Paper Towel Through-Air Drying and Wet Pressing
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Conventional methods for producing absorbent disposable paper products often 'trade' strength for other properties like stiffness, making it difficult to achieve high toughness and low stiffness simultaneously, especially in premium paper towels, and result in high manufacturing costs and disposal concerns due to the use of latex binders.
Innovation Solution
A method for producing high basis weight, multi-ply paper towels with elevated tensile energy absorption (TEA) and low stiffness by using throughdried or fabric-creped base sheets, which are embossed and drawn to maintain or increase absorbency, while reducing converting loss and using minimal or no latex binder, thereby achieving cloth-like drape and softness.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Use of energy by stationary object
If conventional wet pressing/dry creping processes are used, then energy costs are reduced and production speeds are increased, but product softness and bulk are decreased
Solution Approach 1:
The drying process is segmented into two distinct stages: (1) wet pressing to achieve initial dewatering and consolidation, and (2) through-air drying to provide gentle thermal drying that preserves softness and bulk. This segmentation allows each process to optimize for its specific function, resolving the contradiction between energy efficiency and product quality.
Solution Approach 2:
The invention changes the drying parameters by using ambient or mildly heated air flowing through the web, rather than high-temperature contact drying. This parameter change in drying temperature and method maintains the delicate fiber structure and hydrogen bonding, preserving softness and bulk while still achieving energy-efficient water removal.
2Strength
If through-air drying is used to produce soft, bulky products, then product quality is improved, but energy consumption increases
Solution Approach 1:
Wet pressing is applied as a preliminary action before through-air drying to remove the bulk of the water from the web. This preliminary dewatering reduces the water load that subsequent air drying must handle, significantly reducing the energy required for the through-air drying step while still achieving the desired softness and bulk.
Solution Approach 2:
The invention maintains continuous production by combining wet pressing and through-air drying in a sequential, continuous process. The web moves continuously through both drying stages without interruption, ensuring steady-state operation and energy efficiency while consistently producing high-quality soft and bulky products.
3Strength
If latex binder is used to increase strength, then tensile properties are improved, but manufacturing costs increase and disposal concerns arise
Solution Approach 1:
The invention extracts and eliminates the latex binder component from the paper towel construction. Instead of relying on synthetic adhesives, the process achieves strength through optimized fiber-to-fiber hydrogen bonding created during the wet pressing and through-air drying stages, removing the source of manufacturing costs and disposal concerns associated with latex.
Solution Approach 2:
The invention achieves uniform strength distribution throughout the product through homogeneous fiber bonding via hydrogen bonds formed during controlled drying. This homogeneous bonding structure, created by consistent wet pressing and through-air drying, provides adequate tensile properties without requiring localized adhesive application, reducing manufacturing complexity and cost.
4Strength
If high basis weight is achieved in multi-ply towels, then toughness is improved, but converting loss increases
Solution Approach 1:
The invention converts the potential harm of high converting loss into a benefit by using it to create enhanced fiber bonding and density at the interfaces between plies. The controlled loss during converting, combined with wet pressing and through-air drying, creates strong inter-ply adhesion that improves overall toughness while maintaining acceptable converting efficiency.
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 method results in paper towels with superior tensile properties compared to single-ply products, reduced manufacturing costs, and lower disposal concerns, while maintaining high absorbency and caliper, with converting loss minimized and sometimes even increased, achieving high TEA and low modulus.
Implementation Method 1
thermal dewatering with hot air
Implementation Method 2
transpiration drying with hot air
Implementation Method 3
mechanical removal of water
Implementation Method 4
fabric creping the web from a transfer surface
Implementation Method 5
cross-machine direction embossing of an absorbent paper product, having an undulatory structure, including ridges extending in the machine direction
Implementation Method 6
plies are adhesively secured together
Data Source
Figure 1
Figure 1A
Figure 2
AI summary
A multi-ply absorbent towel made from papermaking fiber comprising at least a first ply and a second ply bonded together, the towel having a basis weight of greater than 30 lbs per 3000 ft2 ream (48.8 gsm) and less than 50 lbs per 3000 ft2 ream (81.4 gsm), wherein the plies are selected and adhered together such that the towel typically exhibits (i) a GM TEA, mm-g/mm2 of greater than [0.00125 (GM Tensile, g/3") - 0.75] and (ii) a GM Tensile Modulus, g/in/%, less than [0.0083 (GM Tensile Strength, g/3") + 15.4] {(i) a GM TEA, mm g/mm2, of greater than [0.00952 (GM Tensile, g/cm) - 0.75] and (ii) a GM Tensile Modulus, g/cm/%, less than [0.0249 (GM Tensile Strength, g/cm) + 6.06}.