Ultrasonic Bonding for Elastic Threads in Sanitary Products
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Solution Overview
Problem
The use of adhesives in manufacturing elastic composite structures for absorbent sanitary products leads to thread breakage and undesirable tactile properties, and there is a need for a method that minimizes or eliminates the use of consumable adhesives while ensuring reliable bonding of elastic threads.
Innovation Solution
An apparatus and method that uses an ultrasonic bonding unit to bond web layers with a bond pattern featuring pairs of adjacent bonds, anchoring elastic threads within passages with a cross-sectional area smaller than the thread's non-tensioned state, thereby securing the threads without the need for adhesives.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If adhesives are used to bond elastic threads in elastic composite structures, then the threads can be secured between web layers, but thread breakage occurs and tactile properties deteriorate (stiffness increases)
Solution Approach 1:
The patent removes adhesives from the bonding process entirely, replacing them with a mechanical anchoring system. The elastic threads are secured through notches in the web layers that create friction-based retention, eliminating the harmful effects of adhesive stiffness and thread breakage while maintaining reliable thread anchoring.
Solution Approach 2:
The patent replaces the chemical bonding mechanism (adhesives) with a mechanical anchoring system. The notches in the web layers create physical interlocking with the elastic threads through friction and geometric constraint, providing reliable anchoring without the harmful side effects of adhesive materials.
2Object-affected harmful factors
If thermal or ultrasonic welding techniques are used to bond elastic threads, then adhesives are eliminated, but thread movement or shifting during manufacturing causes thread breakage or unanchoring
Solution Approach 1:
The patent incorporates notches into the web layers during the forming process, before the elastic threads are threaded through them. These pre-formed notches provide immediate mechanical anchoring as the threads are inserted, preventing movement or shifting that would lead to breakage or unanchoring during subsequent manufacturing operations.
Solution Approach 2:
The patent replaces thermal or ultrasonic welding with a mechanical anchoring system using notches. The notches create friction-based retention and geometric constraint that secures the elastic threads without the movement and shifting problems associated with welding techniques, while also eliminating the need for adhesives.
3Ease of manufacture
If adhesives are used to secure elastic threads, then bonding is achieved, but manufacturing costs increase due to consumable material
Solution Approach 1:
The patent eliminates adhesives from the manufacturing process entirely, replacing them with a reusable mechanical anchoring system based on notches in the web layers. This removes the ongoing cost of consumable adhesive materials while maintaining effective bonding capability through friction-based mechanical retention.
Solution Approach 2:
The notches in the web layers provide self-contained mechanical anchoring without requiring external adhesive materials. The structure itself serves the bonding function through its geometric features, eliminating dependence on consumable substances and reducing manufacturing costs.
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 reduces thread breakage and improves bond reliability, resulting in a softer, more uniform product with enhanced manufacturing efficiency and reduced adhesive costs.
Implementation Method 1
an ultrasonic bonding unit to bond web layers with a bond pattern featuring pairs of adjacent bonds, anchoring elastic threads within passages
Data Source
AI summary
An apparatus and method for manufacturing an elastic composite structure for an absorbent sanitary product includes a bonding unit configured to bond a first web layer to a second web layer via a bond pattern that includes at least one bond line having at least one pair of adjacent bonds. The bonding unit secures an elastic thread within a passage defined by the at least one pair of adjacent bonds. The passage has a cross-sectional area smaller than a cross-sectional area of the elastic thread in a non-tensioned state.