Multilayer Nonwoven Fabric with Low Crystalline Polypropylene
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Solution Overview
Problem
Existing nonwoven fabrics, particularly those made with low crystalline polypropylene, face issues with stickiness during production, reduced stretchability, and compromised low-temperature heat sealability, which affect their performance in applications like disposable diapers and sanitary napkins.
Innovation Solution
A multilayer nonwoven fabric structure is developed, comprising an elastic nonwoven fabric with low crystalline polypropylene and a mixed fiber spunbonded nonwoven fabric on its surface, with specific ratios and properties of thermoplastic elastomers and polyolefins to enhance stretchability and reduce stickiness, while maintaining low-temperature heat sealability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If highly crystalline polypropylene or release agent is added to low crystalline polypropylene to prevent sticking during production, then stickiness is reduced, but residual strain increases and stretchability deteriorates
Solution Approach 1:
The invention changes the molecular weight parameter of the low crystalline polypropylene to a specific range (10,000 to 200,000) to reduce stickiness during production while maintaining stretchability, eliminating the need to add highly crystalline polypropylene or release agents that would compromise elastic properties
Solution Approach 2:
The invention creates a composite structure by laminating the elastic nonwoven fabric (made from low crystalline polypropylene with controlled molecular weight) with a spunbonded nonwoven fabric, combining the benefits of low stickiness during production with maintained stretchability and structural integrity
2Productivity
If sealing temperature is increased to improve heat sealing speed, then sealing efficiency increases, but the sealed portion becomes hard
Solution Approach 1:
The invention changes the molecular weight parameter of the low crystalline polypropylene to enable heat sealing at lower temperatures while maintaining adequate sealing speed, preventing the sealed portion from becoming hard and preserving the soft texture required for hygiene materials
3Ease of operation
If stress at extending is decreased for gentle mounting, then mounting comfort improves, but stress at recovering must be increased to prevent gaps
Solution Approach 1:
The invention changes the molecular weight parameter of the low crystalline polypropylene to optimize the stress characteristics, enabling the fabric to exhibit low stress at extending for gentle mounting while maintaining high stress at recovering to prevent gaps and ensure secure sealing
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 solution provides improved moldability, reduced stickiness, enhanced stretchability, and low-temperature heat sealability, making the fabric suitable for hygiene products that require gentle mounting and secure sealing.
Implementation Method 1
nonwoven fabrics are heat sealed and bonded together in some cases
Data Source
AI summary
A multilayer nonwoven fabric includes: an elastic nonwoven fabric containing a specific low crystalline polypropylene; and a mixed fiber spunbonded nonwoven fabric disposed on at least one surface of the elastic nonwoven fabric, wherein the mixed fiber spunbonded nonwoven fabric contains a long fiber of a thermoplastic elastomer (A) and a long fiber of a thermoplastic elastomer (B) other than the thermoplastic elastomer (A), in a ratio of 10 to 90% by mass:90 to 10% by mass ((A):(B), with the proviso that (A)+(B)=100% by mass).