Flame resistant hotmelt adhesive
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Solution Overview
Problem
Hotmelt adhesives face challenges in achieving a balance of flame resistance, adhesion, bonding strength at elevated temperatures, and low softening points, with existing solutions often compromising on these properties due to the use of halogen-containing flame retardants that are environmentally and health-hazardous, and experiencing agglomeration issues with amorphous poly-α-olefin-based materials.
Innovation Solution
A hotmelt adhesive composition comprising 15-45% tackifying resin, 20-60% single-site catalyzed propylene homopolymer and copolymer, and 15-40% particulate or 4-15% room temperature liquid phosphorous-based compounds, which provides high flame resistance, long open-time, and good adhesion without halogen-containing materials, using a combination of phosphorous-based compounds and hindered amine light stabilizers to enhance flame resistance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If halogen-containing flame retardants are used to achieve flame resistance, then flame resistance is improved, but environmental and health hazards increase
Solution Approach 1:
The patent replaces harmful halogen-containing flame retardants with phosphorous-based compounds that provide equivalent or superior flame resistance without the environmental and health hazards. The phosphorous-based compounds undergo endothermic decomposition and form protective char layers, converting the flame retardancy function into a beneficial process that protects both the substrate and the environment.
Solution Approach 2:
The patent changes the chemical composition parameter from halogen-based to phosphorous-based flame retardants. This parameter change maintains the flame resistance function while eliminating the harmful effects associated with halogen compounds, achieving both fire safety and environmental compatibility.
2Strength
If amorphous poly-α-olefin (APAO) based materials are used to achieve adhesion, then adhesion properties are improved, but residual tack creates agglomeration problems
Solution Approach 1:
The patent extracts and removes the problematic residual tack component from the adhesive system by replacing APAO-based materials with propylene homopolymer and copolymer blends. This extraction eliminates the agglomeration issues while preserving the essential adhesion function through the selected polymer combination and tackifying resin system.
Solution Approach 2:
The patent creates a composite adhesive material combining propylene homopolymer, propylene copolymer, and tackifying resin in specific ratios. This composite formulation achieves the desired adhesion properties without the residual tack problems of pure APAO-based materials, as the composite structure balances cohesion and adhesion characteristics.
3Temperature
If APAO based polymers are used to achieve heat resistance, then heat resistance in unstressed conditions is improved, but cohesion is lost when temperature is applied
Solution Approach 1:
The patent introduces dynamic adaptability to the adhesive system by using propylene homopolymer and copolymer blends that can adjust their mechanical properties in response to temperature changes and applied stress. The formulation maintains cohesion under stress at elevated temperatures through the synergistic interaction of the polymer blend and tackifying resin, allowing the adhesive to remain functional throughout the bonding process and service conditions.
4Reliability
If flame retardants are introduced into the adhesive composition to achieve flame resistance, then flame resistance is improved, but adhesion properties are impaired
Solution Approach 1:
The patent merges the flame retardancy function with the adhesive formulation by incorporating phosphorous-based compounds into the propylene homopolymer and copolymer blend. The flame retardant is integrated at the molecular level within the adhesive matrix, ensuring uniform distribution and compatibility. This merging allows the flame retardant to function as part of the adhesive system rather than as a separate additive, maintaining both flame resistance and adhesion properties.
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 achieves high flame resistance, stable adhesion over a broad temperature range, and fast setting without agglomeration, while maintaining bonding strength at elevated temperatures, even in the absence of halogen-based flame retardants, thus addressing the limitations of existing hotmelt adhesives.
Implementation Method 1
at least one of a phosphorous based compound... provides high flame resistance... in the absence of halogen-based flame retardants
Implementation Method 2
adhesiveness is exhibited after the adhesive is melted by heating and coated onto an adherent, followed by cooling to solidify the adhesive
Implementation Method 3
adhesiveness is exhibited after the adhesive is melted by heating and coated onto an adherent, followed by cooling to solidify the adhesive
Implementation Method 4
hotmelt adhesive composition comprising at least one tackifying resin... good adhesion... stable adhesion over a broad temperature range
Data Source
AI summary
A hotmelt adhesive composition comprising 15 to 45% by weight of at least one tackifying resin, and 20 to 60% by weight of a mixture of at least one single -site catalyzed propylene homopolymer (A) and at least one propylene copolymer (B), wherein the propylene homopolymer (A) has a weight average molecular weight of 20,000 to 145,000, the propylene copolymer (B) has an ethylene comonomer content of 5 to 25% by weight, and the weight ratio of propylene homopolymer (A) to propylene copolymer (B) is from 1:3 to 3:1, wherein the hotmelt adhesive further comprises at least one of the following two components (a) and (b): (a) a particulate phosphorous based compound in an amount of 15 to 40% by weight, or (b) a room temperature liquid phosphorous based compound in an amount of 4 to 15% by weight.