Phosphorus Copolymer Foam Flame Retardancy
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Solution Overview
Problem
Conventional phosphorus-based flame retardants for organic polymers require large quantities, affecting physical properties, are prone to leaching, and complicate polymer processing, especially in the production of nanofoams, leading to issues with cell structure and thermal conductivity.
Innovation Solution
Incorporating a phosphorus-containing thermoplastic random copolymer with a weight average molecular weight of at least 60,000 g/mol and 1.5 to 10% by weight phosphorus into the polymeric matrix, which can be processed into foam bodies with small cell sizes and high porosity, providing effective flame retardancy without significant changes in physical properties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If large quantities of conventional phosphorus-based flame retardants are used to achieve effective flame retardancy, then fire resistance is improved, but physical properties of the polymer are profoundly changed and processing becomes difficult
Solution Approach 1:
The patent changes the molecular weight parameter of the phosphorus compound from low (conventional additives) to high (polymerized form with Mw > 60,000). This parameter change transforms the phosphorus compound from a small molecule additive that plasticizes and complicates processing into a polymer that maintains desirable physical properties and processability while providing flame retardancy
Solution Approach 2:
The patent merges the flame retardant function with the polymer matrix by copolymerizing phosphorus-containing monomers with other monomers to form an integrated copolymer. This eliminates the need for separate flame retardant additives and their associated processing problems, while maintaining effective flame protection
2Reliability
If large amounts of phosphorus compounds are incorporated into the polymer to achieve flame retardancy, then fire resistance is improved, but the polymer requires very tight operating windows that are difficult to maintain in industrial-scale foaming operations
Solution Approach 1:
The patent changes the molecular weight parameter of the phosphorus compound from low (conventional additives with Mw < 1000) to high (copolymer with Mw > 60,000). This parameter change eliminates leaching issues and broadens the foaming process operating window, making industrial-scale production feasible without requiring tight process control
3Reliability
If conventional phosphorus-containing flame retardants are used, then flame retardancy is achieved, but cell structure is affected in adverse ways leading to unduly large or non-uniform cell structure, high foam densities or even foam collapse
Solution Approach 1:
The patent merges the flame retardant function with the polymer matrix through copolymerization, creating an integrated material where the phosphorus-containing copolymer is uniformly distributed at the molecular level. This eliminates the adverse effects on cell structure caused by conventional additives, producing foams with uniform, fine cell structures and appropriate density
Solution Approach 2:
The patent changes the molecular weight parameter of the phosphorus compound from low to high, transforming it from a small molecule additive that disrupts foaming to a polymer that integrates seamlessly with the foam matrix, enabling precise control of cell structure
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 phosphorus-containing copolymers enable the production of foam bodies with improved flame resistance, maintaining processability and thermal insulation properties while reducing the need for high amounts of additives, thus addressing the limitations of conventional flame retardants.
Implementation Method 1
Phosphorus-containing compounds often promote char formation when the polymer is burned. The char forms a physical barrier between the unburned portion of the polymer and the flame front.
Implementation Method 2
Another problem with conventional phosphorus-containing flame retardants is that they can leach from the polymer during polymer processing or during use, especially if they are molecular weights below about 1000.
Implementation Method 3
the transfer of heat through the foam by the gas molecules in the cells can be reduced very significantly if the cell size is reduced to approximately the mean free path of the gas molecules or less
Data Source
AI summary
Polymer foam bodies are made from phosphorus-containing thermoplastic random copolymers of a dialkyl (meth)acryloyloxyalkyl phosph(on)ate. Foam bodies made from these copolymers exhibit increased limiting oxygen indices and surprisingly have good properties. In certain embodiments, the phosphorus-containing thermoplastic copolymer is blended with one or more other polymers and formed into nanofoams.