Phosphonate-Modified Polyurethane Prepolymer for Flame Retardancy
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Solution Overview
Problem
Current polyurethane coatings, especially solvent-based ones, face issues with flammability, environmental harm, and compatibility with flame retardant additives, which affect their performance and safety.
Innovation Solution
A flame retardant prepolymer composition comprising isocyanate-terminated polyurethane prepolymer, prepared with diols, polyols, and phosphonate oligomers, which provides superior flame resistance and environmental sustainability by forming a stable polymeric network with even distribution of flame retardant effects.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Speed
If solvent-based polyurethane coatings are used, then fast drying is achieved, but flammability and environmental harm increase
Solution Approach 1:
The patent changes the fundamental parameter of the solvent system from organic-based to water-based, creating aqueous polyurethane dispersions. This parameter change maintains the coating functionality while eliminating the flammability and environmental harm associated with organic solvents, as water is non-flammable and environmentally benign
Solution Approach 2:
The patent employs water as the solvent medium, which is inexpensive, readily available, and leaves no harmful residues. Water evaporates completely without leaving toxic by-products, effectively replacing expensive and harmful organic solvents with a simple, safe alternative
2Reliability
If inorganic flame retardants are added to polyurethane dispersions, then flame resistance is improved, but material properties are impaired due to high quantities required
Solution Approach 1:
The patent merges the flame retardant function with the polyurethane dispersion matrix by incorporating phosphorus-containing compounds during the polymerization process. This integration allows the flame retardant to become part of the polymer structure itself, eliminating the need for high quantities of separate inorganic additives and avoiding impairment of material properties
Solution Approach 2:
The patent creates a composite polyurethane dispersion system where phosphorus-containing compounds are chemically integrated into the polymer chains. This composite approach provides flame resistance through the phosphorus content while maintaining the structural integrity and performance characteristics of the polyurethane matrix
3Reliability
If phosphorus-containing flame retardants are used, then flame resistance is achieved, but compatibility with the binder and even distribution are insufficient
Solution Approach 1:
The patent combines the phosphorus-containing flame retardant components with the polyurethane binder during the polymerization process, ensuring molecular-level distribution throughout the matrix. This merging eliminates compatibility issues and achieves uniform distribution, as the flame retardant becomes an integral part of the polymer structure rather than a separate additive
Solution Approach 2:
The patent incorporates phosphorus-containing functional groups at specific locations within the polyurethane chain structure, allowing the flame retardant property to be distributed locally throughout the material. This local incorporation ensures even distribution and compatibility while maintaining the overall structural properties of the binder
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 composition achieves excellent flame resistance, as evidenced by a limiting oxygen index of at least 27 and UL-94 VTM test results, while being environmentally friendly and free from harmful additives, ensuring no bleeding or toxic by-products during combustion.
Implementation Method 1
Phosphor-containing flame retardants form a protective layer on the burning surface by charring. This layer has an insulating effect and insulates the oxygen supply to the source of the fire.
Implementation Method 2
In the condensed phase, oxygen-rich phosphorus compounds react preferentially, for example phosphates, phosphonates, while the gas phase mechanism is influenced by hydrogen- and carbon-rich phosphorus compounds. Phosphor-containing flame retardants form a protective layer on the burning surface by charring. This layer has an insulating effect and insulates the oxygen supply to the source of the fire.
Implementation Method 3
At the same time, water is formed by charring, which has a cooling effect.
Data Source
AI summary
The present invention relates to a flame retardant prepolymer composition which is intended primarily for the use in a flame retardant polymer. The inventive flame retardant prepolymer composition comprises at least one isocyanate-terminated polyurethane pre- polymer wherein the at least one isocyanate-terminated polyurethane prepolymer contains at least one phosphonate oligomer, phosphonate monomer or a mixture thereof in an amount of from 5 to 75 parts by weight, referring to the total amount of the at least one isocyanate-terminated polyurethane prepolymer, wherein the at least one phosphonate oligomer, phosphonate monomer or a mixture thereof contains units according to the fol- lowing structural formula (I) of the description in which n is an integer from 1 to 20, R is a C1- 20 alkyl, C2-20 alkene, C2-20 alkyne, C3-20 cycloalkyl, or C6-20 aryl, and R2 is an aliphatic and/or aromatic group, wherein a NCO value is in a range between approximately 2 % to approximately 10 % obtained by titration against a dibutylamine/tolulene solution as per ISO 14896: 2009-07 Method A. Further, the present invention relates to a flame retardant polyurethane composition, methods to prepare the flame retardant polymer and the flame retardant polyurethane composition, and a use of said flame retardant polyurethane composition.