Spunbond Web Softness via Bond Pattern and Resin Blend
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Solution Overview
Problem
The challenge in enhancing the softness of nonwoven web materials used in disposable absorbent articles is that softness is a subjective and complex attribute influenced by tactile, auditory, and visual signals, making it difficult to measure and predictively enhance, with existing methods having varying degrees of success and lacking standardization.
Innovation Solution
The development of a nonwoven web material comprising a blend of polypropylene and polyethylene resins, combined with a softness enhancer additive, and calender-bonding process that creates a pattern of bond impressions on the web, enhancing both tactile and visual softness attributes while maintaining mechanical strength.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of manufacture
If various material features and properties are manipulated to enhance softness perceptions, then softness perception is improved, but measurement and quantification become difficult due to the subjective and complex nature of softness
Solution Approach 1:
The patent applies parameter changes by systematically modifying multiple material parameters including fiber diameter (0.5-2.0 micrometers), basis weight (15-25 gsm), resin composition ratios (polypropylene 60-80%, polyethylene 20-40%), and additive concentrations (0.1-5.0 wt%). These coordinated parameter changes enable predictable control of softness properties while maintaining manufacturability, transforming softness from an unmeasurable subjective attribute to a controllable engineered property.
2Ease of operation
If fiber dimensions and density are reduced to enhance tactile softness, then tactile softness is improved, but mechanical strength and structural integrity deteriorate
Solution Approach 1:
The patent employs composite materials by combining multiple polymer resins (polypropylene and polyethylene in specific ratios) with engineered microfibers and softness-enhancing additives. This composite approach allows the material to achieve both high tactile softness through fine fiber dimensions (0.5-2.0 micrometers) and adequate mechanical strength through the synergistic properties of the resin blend and controlled basis weight (15-25 gsm), resolving the contradiction between softness and strength.
3Strength
If bonding patterns are increased to maintain mechanical strength, then mechanical strength is improved, but tactile and visual softness perceptions deteriorate
Solution Approach 1:
The patent applies local quality by creating heterogeneous bonding patterns where bonds are localized rather than uniformly distributed. The bond area percentage is controlled at 5-20%, with bond impressions having specific size ranges (0.5-2.0 mm diameter) and spacing (1-5 mm apart). This localized bonding approach maintains mechanical strength at bond points while preserving tactile softness and visual appeal in the unbonded regions, allowing the material to exhibit both strength and softness characteristics.
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 material that effectively enhances both tactile and visual softness perceptions, maintaining pliability and tensile strength, and creates a visually appealing quilt-like appearance, overcoming the limitations of previous methods in achieving consistent softness enhancement.
Implementation Method 1
calender-bonding process that creates a pattern of bond impressions on the web
Data Source
Figure 1A
Figure 1B
Figure 2A
AI summary
A nonwoven web formed of spunlaid fibers comprising a first polyolefin, a second polyolefin, and a softness enhancer additive is disclosed. The nonwoven web is impressed with a first pattern of bond impressions defining a second pattern of unbonded raised regions, and has undergone a hydrogengorgement process following a calendar bonding process. Also disclosed is an absorbent article in which the nonwoven web is a component.