Hot Melt Adhesive Bonding Elastic Materials to Biodegradable Plastics
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Solution Overview
Problem
Conventional hot melt adhesives have insufficient adhesiveness and creep resistance when bonding elastic materials to biodegradable plastics, such as polylactic acid-based nonwoven fabrics, leading to poor performance in disposable products like diapers and napkins.
Innovation Solution
A hot melt adhesive comprising a thermoplastic block copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, combined with a tackifying resin, specifically a natural resin and petroleum resin, to enhance coatability, adhesiveness, and creep resistance, ensuring strong bonding and retention of elastic materials on biodegradable plastics.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Ease of operation
If the amount of plasticizer is increased to reduce viscosity and improve coatability, then coatability is improved, but the cohesive force and adhesiveness are lowered
Solution Approach 1:
The patent changes the chemical composition parameters of the adhesive system by introducing a specific copolymer blend (styrene-isoprene-styrene block copolymer with 15-30 mass% styrene content and styrene-acrylonitrile copolymer with 18-35 mass% styrene content) that achieves optimal coatability and bonding strength balance without relying on excessive plasticizer content
Solution Approach 2:
The patent uses a composite material system combining multiple polymer components (SIS block copolymer, SAN copolymer, and tackifying resin) to achieve synergistic effects that simultaneously improve coatability and maintain cohesive force and adhesiveness, avoiding the trade-off present in single-component systems
2Reliability
If conventional hot melt adhesive composition is used, then general bonding is achieved, but adhesiveness and creep resistance to biodegradable plastics are insufficient
Solution Approach 1:
The patent modifies the adhesive composition parameters by incorporating specific copolymers with controlled styrene content ranges (15-30 mass% for SIS, 18-35 mass% for SAN) and tackifying resin content (5-20 mass%), which enhances adhesion to biodegradable plastics while maintaining overall formulation compatibility
Solution Approach 2:
The tackifying resin acts as an intermediary component that mediates the bonding interface between the polymer matrix and biodegradable plastic substrates, improving wetting and adhesion without compromising the structural integrity of the adhesive layer
3Reliability
If elastic material is bonded to paper diaper body with insufficient creep resistance adhesive, then bonding occurs, but the elastic material cannot stay at the bonded position and the diaper does not fit the body
Solution Approach 1:
The patent optimizes the adhesive composition by controlling the styrene content (15-30 mass% in SIS, 18-35 mass% in SAN) and tackifying resin content (5-20 mass%), which enhances creep resistance while maintaining adequate bonding performance for elastic material application
Data Source
AI summary
To provide a hot melt adhesive having excellent coatability, adhesiveness and creep resistance, being able to bond and retain an elastic material to a material containing biodegradable plastics, and a disposable product comprising the hot melt adhesive. A hot melt adhesive comprising (A) a thermoplastic block copolymer which is a copolymer of vinyl aromatic hydrocarbons and conjugated diene compounds, and (B) a tackifying resin, wherein (A) the thermoplastic block copolymer comprises: (A1) a styrene block copolymer having a styrene content of 35 to 50% by mass; and (A2) a styrene block copolymer having a styrene content of more than 10% by mass and less than 35% by mass; (B) the tackifying resin comprises: (B1) a natural resin; and the component (B1) being contained in an amount of 20 parts by mass or more based on 100 parts by mass of the component (B).