Tackifier-Free Adhesive Bonding for Substrates
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Solution Overview
Problem
Existing methods for bonding substrates in absorbent articles, such as diapers and sanitary napkins, face challenges including the need for high energy transfer times, the use of tacky adhesives that contaminate equipment, and the requirement for complex and expensive bonding apparatuses. Additionally, current hot melt adhesives may not provide sufficient peel resistance at body temperature for sustained durations.
Innovation Solution
A method and apparatus for bonding substrates using a substantially tackifier free adhesive, where a layer of the adhesive is applied to one substrate, and the substrates are pressed together to force the adhesive into the substrates, creating a bond without the adhesive penetrating completely through the substrates. This approach eliminates the need for long heat transfer dwell times and vacuum control, and reduces the risk of adhesive contamination.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If traditional hot melt adhesives are used for bonding substrates, then bonding strength is achieved, but the adhesives remain tacky and contaminate equipment and substrates
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive by formulating a tackifier-free hot melt adhesive composition. This parameter change eliminates the tacky residue problem while maintaining bonding strength, as the adhesive sets completely without leaving harmful residues on equipment or substrates.
2Reliability
If traditional bonding methods are used to achieve sufficient peel resistance, then bonding strength is improved, but long heat transfer dwell times are required
Solution Approach 1:
The patent modifies the adhesive formulation by removing tackifiers and adjusting the hot melt polymer composition, which changes the thermal bonding parameters. This allows the adhesive to achieve sufficient peel resistance at body temperature for extended wear periods while requiring significantly reduced heat transfer dwell times, thereby increasing production efficiency.
3Manufacturing precision
If vacuum control is incorporated into the bonding apparatus to control patch formation, then bonding precision is improved, but device complexity and cost increase
Solution Approach 1:
The patent extracts and eliminates the need for vacuum control systems from the bonding apparatus. By using a tackifier-free adhesive formulation that sets completely without requiring vacuum control for patch formation, the design removes this complex subsystem while maintaining manufacturing precision and reducing equipment cost.
4Reliability
If adhesive is applied to discrete parts before assembly, then bonding is achieved, but adhesive migrates and contaminates equipment and other substrates
Solution Approach 1:
The patent changes the physical and chemical parameters of the adhesive by formulating a tackifier-free composition. This parameter change prevents adhesive migration during handling and assembly operations, as the adhesive sets completely upon contact with the receiving substrate without remaining tacky enough to migrate to other surfaces or contaminate equipment.
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 strong, tackifier-free bonds that provide sufficient peel resistance at body temperature for extended durations, while also preventing adhesive contamination and reducing manufacturing costs by simplifying the bonding process.
Implementation Method 1
applying a layer of substantially tackifier free adhesive to the first surface of the second substrate to define an adherence zone; positioning the second surface of the first substrate on the adherence zone of the second substrate; and pressing the first substrate and the second substrate against each other in the adherence zone such to force a first portion of the layer of the substantially tackifier free adhesive into the first substrate and a second portion of the layer of the substantially tackifier free adhesive into the second substrate
Data Source
AI summary
The present disclosure relates to bonding a first substrate together a second substrate with adhesives that are substantially tackifier free. A layer of substantially tackifier free adhesive may be applied to a first surface of the second substrate to define an adherence zone, and the first substrate is positioned on the adherence zone of the second substrate to form a laminate. The first and second substrates are pressed against each other in the adherence zone to force the substantially tackifier free adhesive to penetrate into the first and second substrates. A first portion of the layer of the adhesive penetrates into the first substrate and a second portion of the layer of the adhesive penetrates into the second substrate. A central portion of the layer of the adhesive between the first and second portions separates the second surface of the first substrate from the first surface of the second substrate.