Elastic Hot Melt Adhesive Composition with Low Viscosity
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Solution Overview
Problem
Formulating a low viscosity hot melt adhesive with good elastic recovery and high peel adhesion is challenging due to the limited availability of styrene block copolymers with high melt flow rates, which often compromise mechanical properties when attempting to achieve such characteristics.
Innovation Solution
A hot melt adhesive composition incorporating at least 15% by weight of a styrene block copolymer with a melt flow rate of at least 15 g/10 minutes and a diblock content of no greater than 10%, along with a tackifying agent, to achieve a viscosity of no greater than 7,000 cps at 177°C, providing elasticity and high peel adhesion in a 3-layer elastic composite.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If styrene block copolymers with high melt flow rate are used to achieve low viscosity, then viscosity is reduced and applicability improves, but mechanical properties deteriorate due to high di-block content
Solution Approach 1:
The invention changes the chemical composition parameters of the styrene block copolymer by limiting diblock content to 10% or less and requiring at least 20% triblock content. This parameter change enables the polymer to achieve both low viscosity (through high melt flow rate) and good mechanical properties (through controlled block structure), resolving the contradiction between viscosity reduction and mechanical property maintenance
Solution Approach 2:
The invention creates a composite adhesive system by combining the specially formulated styrene block copolymer with tackifying resins and plasticizers. This composite approach allows the triblock copolymer to provide structural integrity and elastic recovery while the tackifying resin enhances adhesion, achieving both low viscosity for easy application and high mechanical properties for strong bonding
2Stability of the object's composition
If high melt flow rate styrene block copolymers are used to achieve low viscosity, then low viscosity is achieved, but elastic recovery deteriorates
Solution Approach 1:
The invention changes the architectural parameters of the styrene block copolymer by specifying at least 20% triblock content and limiting diblock to 10% or less. The triblock structure provides physical crosslinking that enables elastic recovery, while the high melt flow rate ensures low viscosity. This parameter change resolves the contradiction between achieving low viscosity and maintaining elastic recovery
Solution Approach 2:
The invention applies local quality by creating distinct functional regions within the adhesive: the triblock copolymer segments provide elastic recovery and structural integrity, while the overall low molecular weight and high melt flow rate characteristics provide low viscosity. This localized functional distribution resolves the contradiction between viscosity and elastic recovery
3Stability of the object's composition
If high melt flow rate styrene block copolymers are used to achieve low viscosity, then low viscosity is achieved, but peel adhesion deteriorates
Solution Approach 1:
The invention creates a composite adhesive formulation combining the low viscosity styrene block copolymer (providing flow and elasticity) with tackifying resins (providing adhesion). The tackifying resin component specifically addresses peel adhesion while the copolymer maintains low viscosity, resolving the contradiction between viscosity reduction and adhesion maintenance
Solution Approach 2:
The invention changes the compositional parameters by formulating a multi-component system where the styrene block copolymer (with controlled diblock ≤10% and triblock ≥20%) provides viscosity control and elastic properties, while tackifying resin content is optimized to provide high peel adhesion. This parameter optimization resolves the contradiction between low viscosity and high peel adhesion
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 adhesive composition enables the creation of elastic composites with excellent elastic recovery and high peel adhesion, allowing for efficient application at high line speeds and targeted elastic performance in disposable articles like diapers and medical bandages.
Implementation Method 1
providing elasticity in the bonded area
Implementation Method 2
thereby permanently bonding the first and second substrates to each other
Data Source
AI summary
This invention claims hot melt adhesive compositions that can be used to form elastic composites that are useful in disposable absorbent articles. The compositions have good elastic recovery and high peel adhesion at a viscosity of less than about 20,000 cps at 177°C. The low viscosity makes it possible to apply the adhesive at a high line speed and target application to only those areas requiring elastic performance.