Embossed fibrous structures and methods for making same
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Solution Overview
Problem
Embossed fibrous structures comprising filaments, such as polyvinyl alcohol or starch filaments, face consumer acceptance issues due to embossments that relax and become less visible, and existing methods do not effectively create visible embossments in multi-ply sanitary tissue products with polysaccharide filaments.
Innovation Solution
The method involves embossing a multi-ply fibrous structure with a heated emboss roll or passing it through a nip formed by a heated anvil roll and a non-heated emboss roll to create embossed multi-ply sanitary tissue products, ensuring the embossments are more permanent and visible.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If a non-heated embossing roll and rubber roll are used to emboss fibrous structures, then the embossing process is simpler and energy consumption is lower, but the embossments relax and become less visible
Solution Approach 1:
The patent changes the temperature parameter of the embossing roll from non-heated to heated (e.g., 50-200°C), which fundamentally alters the embossing mechanism. The heat activates the filament material (especially starch or polyvinyl alcohol), causing it to soften and set in the embossed pattern, thereby preventing relaxation and maintaining visibility.
Solution Approach 2:
The patent applies moisture to the fibrous structure before embossing. This preliminary action prepares the material by plasticizing the filaments, making them more pliable and responsive to the embossing heat and pressure, ensuring the embossments set properly and remain visible.
2Ease of operation
If steam is applied to cellulosic pulp fiber fibrous structures to reduce modulus before embossing, then the fibrous structures become more pliable for embossing, but the tensile strength decreases due to disruption of hydrogen bonds
Solution Approach 1:
Instead of using steam (which causes hydrogen bond disruption), the patent uses controlled moisture application combined with heat. This alternative parameter combination achieves pliability through thermal activation and moisture plasticization without the severe tensile strength loss associated with steam treatment.
Solution Approach 2:
The patent replaces the steam-based softening mechanism with a heat-and-moisture combination. This substitution avoids the hydrogen bond disruption caused by steam while achieving the same pliability effect through thermal softening and moisture plasticization of the filaments.
3Strength
If thermal bonds are imparted to fibrous structures comprising filaments, then the filaments fuse together providing strength and integrity, but the embossments may be compromised by the bonding process
Solution Approach 1:
The patent merges the embossing and thermal bonding operations into a single integrated process. The heated embossing roll simultaneously provides both the heat for thermal bonding and the pressure for embossing, ensuring that filaments fuse within the embossed patterns while maintaining sharp definition. This eliminates the need for separate bonding steps that could blur embossment boundaries.
Solution Approach 2:
The patent applies moisture before embossing to prepare the filaments for thermal bonding. This preliminary plasticization ensures that the filaments will bond effectively during the embossing process while maintaining embossment definition, resolving the conflict between bonding strength and embossment sharpness.
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
This approach results in embossed fibrous structures with more permanent embossments that are visible to consumers, enhancing the appearance and durability of multi-ply sanitary tissue products.
Implementation Method 1
embossing a multi-ply fibrous structure with a heated emboss roll or passing it through a nip formed by a heated anvil roll and a non-heated emboss roll
Data Source
AI summary
Embossed fibrous structures containing a plurality of filaments and methods for making same are provided.