Nonwoven Web Softness via Patterned Calender Bonding
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Solution Overview
Problem
Current methods for enhancing the softness of nonwoven web materials in disposable absorbent articles face challenges in precisely measuring and achieving softness while maintaining tensile strength, as increasing basis weight or using bicomponent fibers can increase costs and compromise mechanical properties.
Innovation Solution
A nonwoven web with a basis weight of 20-30 gsm, formed from a polypropylene and polyethylene blend, is calender-bonded with a pattern and hydroengorged, featuring a white-tinting agent and a thermoplastic polymeric film, to enhance visual and tactile softness while maintaining tensile strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If basis weight of nonwoven web is increased to enhance softness, then visual and tactile softness improve, but manufacturing cost increases
Solution Approach 1:
The patent applies local quality by creating bond impressions with varying depths and patterns in specific regions of the nonwoven web. The calendering process imparts a patterned structure where certain areas have compressed bonds while others retain loft, providing softness enhancement without uniformly increasing basis weight across the entire material.
Solution Approach 2:
The patent changes physical parameters of the nonwoven web through calendering temperature, pressure, and pattern design. By controlling the calendering parameters (temperature range, pressure applied, roller pattern), the invention achieves softness enhancement through structural modification rather than increasing material quantity, thereby avoiding higher manufacturing costs associated with increased basis weight.
2Ease of manufacture
If bicomponent fibers are used to enhance softness, then tactile softness improves, but tensile strength decreases
Solution Approach 1:
The patent applies local quality by creating bond impressions with varying depths and patterns in specific regions of the nonwoven web. The calendering process imparts a patterned structure where certain areas have compressed bonds while others retain loft, providing softness enhancement without uniformly increasing basis weight across the entire material.
Solution Approach 2:
The patent uses composite materials by combining polypropylene and polyethylene polymers in a bicomponent fiber system. This composite approach allows the material to exhibit both softness characteristics from the fiber composition and adequate tensile strength through the synergistic properties of the polymer blend, resolving the contradiction between softness and strength.
3Ease of manufacture
If calender bonding is applied to enhance softness, then visual appearance improves, but structural integrity may be compromised
Solution Approach 1:
The patent applies local quality by creating bond impressions with varying depths and patterns in specific regions of the nonwoven web. The calendering process imparts a patterned structure where certain areas have compressed bonds while others retain loft, providing softness enhancement without uniformly increasing basis weight across the entire material.
Solution Approach 2:
The patent applies partial action by using controlled calendering that creates bond impressions only in specific patterns rather than uniformly across the entire web. The bond area percentage is controlled to maintain structural integrity while providing sufficient visual and tactile softness in the bonded regions, avoiding excessive compression that would compromise overall structural stability.
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 approach results in a product with improved visual and tactile softness attributes and enhanced tensile strength, balancing cost-effectiveness with desired mechanical properties, maintaining pliability and structural integrity.
Implementation Method 1
The nonwoven web is calender-bonded with a pattern to enhance visual and tactile softness
Implementation Method 2
The nonwoven web is hydroengorged to enhance visual and tactile softness attributes
Data Source
AI summary
An absorbent article having improved softness signals is disclosed. The article may include a topsheet or a backsheet including a nonwoven web. The web may have a basis weight of 30 gsm or less, may be formed of spunlaid fibers including polyolefin and up to 5 percent by weight TiO2, and may be impressed with a pattern of bond impressions to a bond area percentage of at least 10 percent forming a pattern of bonded regions and raised regions. The web may have opacity of 42 or greater; have an average height difference between bonded regions and raised regions of at least 280 μm; be hydroengorged; and/or have a cross-machine direction tensile strength of 350 gf/cm. A nonwoven web manufactured to have a suitable combination of such features exhibits an enhanced appearance of softness, soft tactile feel and satisfactory mechanical attributes, while being relatively cost effective.