Expandable Microspheres in Tissue Webs for Bulk
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Producing premium quality soft tissue sheets with adequate softness, bulk, and strength is challenging for conventional tissue machines without the expense of a layered headbox or throughdryer, as existing methods often compromise on softness or strength to achieve bulk.
Innovation Solution
Incorporating expandable microspheres mixed with a polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer dispersion into the tissue web, eliminating the need for cationic retention aids and enhancing bulk without reducing softness or strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Volume of stationary object
If embossing is used to increase bulk, then bulk is improved, but sheet strength is reduced below acceptable levels
Solution Approach 1:
Expandable microspheres act as intermediary elements between fibers, providing bulk through their expansion capability while the polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer serves as a binding mediator that maintains sheet strength. The microspheres expand to create void space for bulk without compromising the fiber network integrity.
Solution Approach 2:
The invention changes the physical state parameter of the microspheres from compressed (in the dry state during manufacturing) to expanded (after exposure to moisture), thereby increasing bulk without affecting the fundamental fiber structure and strength properties of the sheet.
2Strength
If basis weight is reduced to decrease stiffness, then softness is improved, but multiple plies are required to maintain caliper and performance
Solution Approach 1:
The invention changes the bulk parameter through microsphere expansion rather than reducing basis weight, allowing single-ply sheets to achieve adequate caliper and performance. This eliminates the need for multiple plies while maintaining softness.
3Reliability
If cationic retention aids are used to improve retention and distribution of expandable microspheres, then retention is improved, but product complexity and cost increase
Solution Approach 1:
The polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer acts as an intermediary that facilitates the retention and distribution of expandable microspheres without requiring cationic retention aids. This polymer-stabilized dispersion system simplifies the formulation while achieving reliable microsphere incorporation.
4Volume of stationary object
If conventional methods are used to achieve bulk, then bulk is improved, but softness is compromised
Solution Approach 1:
Expandable microspheres serve as intermediary elements that increase bulk through internal expansion rather than external compression, preserving the soft, airy feel of the sheet. The microspheres create void space without densifying the fiber structure, thereby maintaining softness while achieving bulk.
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 achieves a significant increase in bulk by up to 10% compared to sheets without microspheres, maintaining softness and strength, and can produce tissue webs with basis weights of at least 10 gsm and bulk of at least 10 cc/g, suitable for premium tissue products.
Implementation Method 1
expandable microspheres
Implementation Method 2
expandable microspheres
Implementation Method 3
polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer
Implementation Method 4
nonionic surfactant
Data Source
Figure 1A~2B
AI summary
The disclosure relates to high bulk tissue webs containing microspheres. To form the tissue webs, a nonionic polymer dispersion, such as polyvinyl alcohol stabilized vinyl acetate-ethylene copolymer dispersion, is mixed with microspheres and incorporated into tissue webs to increase sheet bulk.