Injection-foaming Thermoplastic Resin With Controlled Cell Density
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Existing injection-foaming methods for thermoplastic resins face challenges such as the generation of corrosive decomposition products, environmental pollution, difficulty in producing foamed products with predetermined cell density and diameter, and the complexity and legal restrictions associated with supercritical-fluid generators.
Innovation Solution
An injection-foaming method using a molding machine with a feeding and plasticizing unit, where a mixture of a foam nucleating agent and a foaming gas is used as the foaming agent, fed at a controlled pressure of 0.1-1.0 MPa, allowing for the production of foamed products with predetermined cell diameter and density without harmful decomposition products or the need for supercritical-fluid generators.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-generated harmful factors
If chemical foaming agents are used, then foamed products can be produced, but corrosive decomposition products are generated causing environmental pollution and harm to human health
Solution Approach 1:
The patent converts the harmful chemical decomposition issue into a beneficial physical process by using physical foaming agents (nitrogen, carbon dioxide, air) that do not decompose harmfully. The foaming is achieved through physical dissolution and phase separation mechanisms, transforming a harmful chemical process into a safe physical one while maintaining product quality
Solution Approach 2:
The patent changes the fundamental parameter of the foaming mechanism from chemical decomposition to physical phase change. By controlling temperature, pressure, and the physical properties of the foaming agent, the process achieves foaming without chemical reactions, thereby eliminating corrosive decomposition products while maintaining manufacturing effectiveness
2Object-generated harmful factors
If physical foaming agents are used, then environmental pollution is reduced, but it is difficult to produce foamed products with predetermined cell density and diameter
Solution Approach 1:
The patent introduces a nucleating agent as an intermediary substance that facilitates controlled bubble formation. This nucleating agent acts as a mediator between the physical foaming agent and the resin matrix, enabling precise control over cell nucleation, growth, and distribution to achieve predetermined cell density and diameter while maintaining environmental benefits
Solution Approach 2:
The patent implements feedback control mechanisms to monitor and adjust foaming parameters in real-time. By controlling temperature, pressure, and residence time, the system dynamically adjusts the foaming process to achieve target cell characteristics, ensuring precise control over cell density and diameter throughout the manufacturing process
3Quantity of substance
If supercritical-fluid generators are used, then high cell density can be achieved, but the system becomes complex and subject to legal restrictions
Solution Approach 1:
The patent extracts and eliminates the complex supercritical-fluid generation system from the process. Instead of using high-pressure supercritical fluids requiring specialized generators and feeders, the invention employs simple physical foaming agents that can be introduced through standard injection molding equipment, thereby achieving high cell density without the associated complexity and legal restrictions
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
This method enables the simple, safe, and efficient production of foamed products with controlled cell diameter and density, reducing environmental impact and eliminating the use of harmful foaming agents, while avoiding the complexity and legal issues associated with high-pressure systems.
Implementation Method 1
the mixture is fed to a feeding part or a plasticizing part of an injection unit at a pressure of 0.1 MPa or more and less than 1.0 MPa
Implementation Method 2
allowing the resin to expand... enlarging of the mold cavity for allowing the foaming-agent-containing melted resin to expand
Implementation Method 3
a thermoplastic resin fed from the feeding part is plasticized... the resultant resin is injected as a foaming-agent-containing melted resin
Data Source
AI summary
An injection-foaming method for a thermoplastic resin comprising using an injection unit 30 provided with a hopper 35, a plasticizing cylinder 31 and a screw 32, and a mold 10 having a mold cavity 10a of changeable capacity; filling the mold cavity 10a with a foaming-agent-containing melted resin injected from the injection unit 30; and then enlarging the mold cavity 10a for allowing the foaming-agent-containing melted resin to expand, wherein inclusion of a foaming agent into a thermoplastic resin is done by using a mixture of a foam nucleating agent and a foaming gas as foaming agent, feeding the mixture to hopper 35 or plasticizing cylinder 31 and screw 32 of injection unit 30 at a pressure of 0.1 MPa or more and less than 1.0 MPa, and contacting the mixture with a pre- or post-plasticized thermoplastic resin present in hopper 35 or plasticizing cylinder 31 and screw 32.