Elevator Belt Tie-Layer for Adhesion and Flame Resistance

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Solution Overview

Problem

Elevator belts with polyurethane sheaths and polymer matrix composite cores face challenges in adhesion and poor fire resistance, failing to meet safety standards despite reactivation methods.

Innovation Solution

A thermoplastic polyurethane or elastomer sheath with a phosphonate blended bonding agent is used to adhere the core, forming a tie-layer between the sheath and core, enhancing adhesion and fire resistance by incorporating phosphonate polymers and oligomers, which are extruded or applied via pultrusion.

Engineering Contradictions & Design Principles

VSEngineering Contradiction Analysis

1Strength

If a polyurethane sheath is adhered to a polymer matrix composite core using conventional bonding agents, then the belt structure is formed, but adhesion between the sheath and core remains poor

Engineering Contradiction:
Improveadhesion strengthVSAvoidbonding reliability
Core Design Contradiction:
StrengthVSReliability

Solution Approach 1:

The bonding agent's chemical composition is modified by incorporating phosphonate groups (such as phosphonic acid, phosphonates, or phosphonocarbonates) at concentrations of 0.1-50%, which changes the chemical parameters of the adhesive to achieve superior adhesion between the polyurethane sheath and PMC core

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The bonding agent is formulated as a composite material combining polyurethane with phosphonate-containing compounds, creating a multi-component adhesive system that provides both mechanical bonding and chemical adhesion to the carbon fiber/epoxy core

Inventive Principle:
Principle #40Composite materials

2Object-affected harmful factors

If conventional polymer matrix composite cores and elastomer sheaths are used, then the belt structure is formed, but fire resistance remains poor

Engineering Contradiction:
Improvefire resistanceVSAvoidsafety compliance
Core Design Contradiction:
Object-affected harmful factorsVSReliability

Solution Approach 1:

The chemical composition of the bonding agent is modified to include phosphonate groups (phosphonic acid, phosphonates, or phosphonocarbonates) at concentrations of 0.1-50%, which fundamentally changes the fire resistance parameters of the belt system by promoting char formation and reducing flammability

Inventive Principle:
Principle #35Parameter changes

Solution Approach 2:

The bonding agent is formulated as a composite material combining polyurethane with phosphonate-containing compounds, creating a fire-retardant adhesive system that provides both bonding functionality and flame resistance to meet safety standards

Inventive Principle:
Principle #40Composite materials

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 flame resistance without using halogens, maintaining mechanical properties and meeting fire retardation standards.

Implementation Method 1

A TPU or other elastomer or rubber and phosphonate blended bonding agent adheres the core to the sheath

Methodology Applied
Scientific EffectAdhesion: Adhesive

Data Source

PatentEP3318395B1Load bearing member for an elevator system having an elastomer and phosphonate blended bonding agent
Publication Date: 2021.05.05 OTIS ELEVATOR CO
  • EP3318395B1 patent drawingFigure 1
  • EP3318395B1 patent drawingFigure 2~3
  • EP3318395B1 patent drawingFigure 4

AI summary

A belt (50) for an elevator system is provided having a core (54) and an elastomeric sheath (52) positioned over the core. An elastomer and phosphonate blended bonding agent (56) adheres the core (54) to the sheath (52).