UV-Curable Hot Melt Adhesive for Absorbent Articles
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Solution Overview
Problem
Conventional hot melt adhesives used in absorbent articles fail to bond well with microfibre fabrics, lead to staining and reduced bonding performance on breathable films, and are adversely affected by fragrances or lotions, resulting in unacceptable bonding and residue issues.
Innovation Solution
Radiation curable hot melt adhesives, specifically comprising acrylic polymers and tackifying resins, are applied to absorbent articles and cured with UV irradiation, providing stable bonding to various fabrics without staining breathable films and resisting fragrances or lotions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If conventional hot melt adhesives are used for bonding absorbent articles to fabrics, then the adhesive provides initial bonding capability, but the bonding performance varies significantly across different fabric types (cotton vs. microfibre) and staining occurs on breathable films
Solution Approach 1:
The patent changes the chemical parameters of the adhesive by incorporating UV-curable functional groups (acrylate, epoxy, or isocyanate groups) into the polymer structure. This allows the adhesive to undergo chemical transformation upon UV exposure, creating crosslinked networks that provide consistent bonding across different fabric types including cotton and microfibre, while preventing staining on breathable films through controlled polymerization.
Solution Approach 2:
The invention creates a composite adhesive system combining conventional hot melt adhesive components with UV-curable functional monomers or oligomers. This composite structure integrates the initial bonding capability of hot melt adhesives with the enhanced adhesion and stability of crosslinked polymer networks, achieving versatile bonding performance across different fabrics without staining.
2Strength
If higher tack positioning adhesives are developed to improve bonding to microfibre fabrics, then bonding to microfibre improves, but bonding becomes too aggressive to cotton and nylon fabrics
Solution Approach 1:
The patent applies local quality by creating different adhesive formulations with tailored functional group compositions and molecular weights suited for specific fabric types. The UV-curable adhesive system allows for localized optimization of bonding characteristics through selective crosslinking density and functional group distribution, enabling appropriate bonding strength for each fabric type without excessive adhesion.
3Reliability
If conventional positioning adhesives are used with breathable PE films, then the back sheet provides breathability, but low molecular ingredients of the adhesive migrate into the breathable film causing staining and significantly reducing bonding performance
Solution Approach 1:
The invention utilizes phase transition by transforming the adhesive from a low-viscosity state (before UV curing) to a crosslinked solid network state (after UV exposure). This phase transition locks the adhesive components in place, preventing low molecular ingredients from migrating into the breathable PE film while maintaining the film's breathability and eliminating staining issues.
Solution Approach 2:
The patent replaces the reliance on mechanical adhesion (physical bonding through van der Waals forces) with chemical bonding through UV-induced crosslinking. This substitution creates a more stable adhesive system that resists migration and staining while maintaining effective bonding performance on breathable films.
4Ease of operation
If conventional hot melt adhesives are used in absorbent articles containing fragrances or lotions, then the adhesive provides positioning function, but performance is adversely affected by the presence of fragrances or lotions
Solution Approach 1:
The patent converts the potential harm of fragrances and lotions (which can interfere with conventional adhesive bonding) into a benefit by using UV-curable chemistry that is less sensitive to these contaminants. The photopolymerization process creates a crosslinked network that is more resistant to chemical interference, allowing the adhesive to maintain reliable positioning function even in the presence of fragrances and lotions.
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 radiation curable adhesives exhibit excellent bonding balance across different fabrics, maintain stability over time, prevent adhesive transfer, and are resistant to lotions and fragrances, ensuring secure attachment and easy removal without residue.
Implementation Method 1
Radiation curable hot melt adhesives, specifically comprising acrylic polymers and tackifying resins, are applied to absorbent articles and cured with UV irradiation
Data Source
AI summary
An article comprising an adhesive attachment region is provided. The adhesive attachment region comprises a radiation curable hot melt pressure sensitive adhesive.