Elevator Belt Tie-Layer Composition for Core-Sheath Adhesion
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Solution Overview
Problem
Elevator systems face challenges with poor adhesion between polyurethane or elastomer sheaths and polymer matrix composite cores, and inadequate fire resistance in load-bearing belts, which are critical for safety and functionality.
Innovation Solution
A thermoplastic polyurethane or elastomer and phosphonate blended bonding agent is used as a tie-layer between the core and sheath in elevator belts, enhancing adhesion and fire resistance by incorporating poly-phosphonate homopolymers, oligomers, and copolymers, which are extruded or co-extruded onto the core and sheath.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Strength
If a polyurethane sheath is adhered to a polymer matrix composite core, then the belt structure is formed, but poor adhesion between the sheath and core occurs
Solution Approach 1:
A bonding agent layer is introduced as an intermediary between the polyurethane sheath and the polymer matrix composite core. This bonding agent contains phosphonate compounds that chemically interact with both the elastomer sheath and the composite core, creating strong interfacial adhesion. The bonding agent acts as a mediator that bridges the two materials, resolving the adhesion problem between the sheath and core.
Solution Approach 2:
The bonding agent is formulated as a composite material containing phosphonate compounds blended with elastomeric polymers. This composite bonding agent combines the adhesive properties of phosphonates with the flexibility and compatibility of elastomers, enabling it to bond effectively to both the polyurethane sheath and the composite core while maintaining the required mechanical properties.
2Object-affected harmful factors
If conventional materials are used for the core and sheath, then the belt structure is simple, but fire resistance is inadequate
Solution Approach 1:
Phosphonate compounds are incorporated into the bonding agent at specific concentrations (e.g., 1-30% by weight) to achieve fire resistance. The phosphonate content and molecular structure are optimized to provide flame retardancy while maintaining adhesion performance. This parameter optimization allows conventional-looking materials to achieve enhanced fire resistance without drastic structural changes.
Solution Approach 2:
The phosphonate-containing bonding agent serves as a fire-resistant intermediary layer that protects the interface between the sheath and core. This bonding agent layer acts as a thermal barrier and flame retardant, preventing fire propagation while maintaining the structural integrity of the belt. The phosphonates decompose endothermically, absorbing heat and releasing flame-inhibiting gases.
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 solution improves adhesion between the sheath and core, and significantly enhances the fire resistance of elevator belts without using halogens, maintaining mechanical properties and allowing for the use of flame retardants in the polymer composite belt design.
Implementation Method 1
A TPU or other elastomer or rubber and phosphonate blended bonding agent adheres the core to the sheath
Implementation Method 2
the fiber/epoxy composite core and the elastomer have poor fire resistance. Fire retardation standards are some of the key safety requirements that each belt is required to meet
Data Source
AI summary
A belt for an elevator system is provided having a core and an elastomeric sheath positioned over the core. An elastomer and phosphonate blended bonding agent adheres the core to the sheath.