Biodegradable, Industrially Compostable, And Recyclable Injection Molded Microcellular Flexible Foams

What is this patent about?

’704 is related to the field of manufacturing flexible foams, specifically addressing the environmental concerns associated with traditional foam production. Conventional flexible foams often rely on non-renewable materials, chemical blowing agents, and crosslinking, leading to products that are difficult to recycle and contribute to landfill waste. The patent aims to provide a process for creating recyclable foams using more sustainable methods and materials.

The underlying idea behind ’704 is to use a supercritical fluid (SCF) , such as nitrogen or carbon dioxide, as a physical blowing agent in conjunction with recyclable thermoplastic polymers. This eliminates the need for chemical blowing agents and crosslinking, which hinder recyclability. The SCF is mixed with the molten polymer to create a single-phase solution, which is then injected into a mold. The pressure drop in the mold causes the SCF to come out of solution, creating the foam structure.

The claims of ’704 focus on a method for manufacturing a flexible foam. The method involves forming a molten polymer from a thermoplastic masterbatch containing recyclable thermoplastic polymers, mixing a supercritical fluid with the molten polymer to create a single-phase solution, introducing the solution into a mold cavity pressurized with a counterpressure gas, and foaming the solution by allowing the supercritical fluid to come out of solution. A key aspect is that the thermoplastic polymers do not cross-link during manufacturing.

In practice, the process involves carefully controlling several parameters. The thermoplastic polymer is melted and mixed with the SCF in a specialized injection molding machine. The gas counter pressure is used to control the expansion of the foam and prevent surface defects. Dynamic mold temperature control is employed to ensure consistent cell structure. The resulting foam can then be used in various applications, such as shoe midsoles, furniture cushioning, and automotive components.

The differentiation from prior approaches lies in the combination of using recyclable thermoplastic polymers, a supercritical fluid as a blowing agent, and the absence of crosslinking. This allows the resulting foam to be recycled at the end of its life, closing the loop and reducing environmental impact. The use of gas counter pressure and dynamic mold temperature control further enhances the quality and consistency of the foam structure, making it a viable alternative to traditional, less sustainable flexible foams.