Liquid Blowing Agent Formulation for PVC Foaming
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Solution Overview
Problem
Solid formulations of chemical blowing agents for thermoplastic polymers, such as PVC, are difficult to handle and distribute evenly, leading to inconsistent cell structures and surface finishes in extruded sheets.
Innovation Solution
A liquid formulation comprising a carrier and a chemical blowing agent with 1 wt% or less water, which includes exothermic and endothermic agents, surfactants, and desiccants, ensuring stable and even distribution within the polymer for consistent cell structure and surface finish.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If solid formulations (pellets or powders) are used to deliver chemical blowing agents, then the formulation is stable and easy to store, but it is difficult to handle, accurately dose, and distribute evenly throughout the thermoplastic polymer
Solution Approach 1:
The patent changes the physical state of the blowing agent formulation from solid (pellets or powders) to liquid form. This parameter change enables the formulation to be pumped, metered, and distributed easily through liquid delivery systems while maintaining stability through controlled water content (less than 1 wt%) and appropriate chemical composition.
Solution Approach 2:
The patent introduces a liquid carrier as an intermediary medium to dissolve or disperse the chemical blowing agents. This liquid carrier facilitates easy handling, accurate dosing, and uniform distribution of the blowing agents throughout the thermoplastic polymer melt, while the formulation's low water content ensures stability.
2Reliability
If solid formulations are used, then the formulation is stable, but even distribution of the blowing agent throughout the thermoplastic polymer is difficult to ensure, leading to inconsistent and coarser cell structures
Solution Approach 1:
Changing from solid to liquid formulation enables molecular-level dispersion of the blowing agents throughout the polymer melt, ensuring uniform distribution and consistent cell structure. The liquid state allows the formulation to flow and distribute evenly, eliminating the aggregation issues inherent in solid pellets or powders.
Solution Approach 2:
The liquid formulation can be delivered through hydraulic or pneumatic systems (pumping and metering systems), enabling precise control of distribution and flow characteristics that ensure even dispersion of blowing agents throughout the thermoplastic material, resulting in consistent cellular foam structures.
3Ease of operation
If liquid formulations with higher water content are used, then the formulation is easier to handle, but the formulation becomes unstable over time with reduced shelf-life
Solution Approach 1:
The patent optimizes the water content parameter to be less than 1 wt%, which is sufficient to maintain liquid formulation properties for easy handling and pumping, while being low enough to prevent premature reaction of water-sensitive blowing agents and ensure long-term stability and extended shelf-life.
Solution Approach 2:
The formulation uses different components with specific local functions: water-sensitive blowing agents are protected from moisture by controlling overall water content, while hydrophilic components are included to maintain liquid flow properties. This local quality differentiation allows the formulation to be both handleable and stable.
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 liquid formulation provides a finer and more consistent cell structure, smooth surface finish, and stable shelf-life, allowing for accurate dosing and handling, while maintaining the color integrity of the final product.
Implementation Method 1
it allows more even distribution within the thermoplastic polymer thereby forming a finer and more consistent cell structure
Implementation Method 2
The formulation may include one or a plurality of exothermic chemical blowing agents
Implementation Method 3
Said formulation may include one or a plurality of endothermic chemical blowing agents
Implementation Method 4
Said formulation preferably includes a surface active agent, for example a surfactant
Implementation Method 5
by ensuring the formulation includes no more than 1 wt % of water, the formulation is stable over time, meaning it has a long shelf-life
Data Source
AI summary
A formulation for foaming a thermoplastic polymer, for example PVC, comprises a carrier, exothermic and endothermic chemical blowing agents and 1 wt %, preferably less than 0.2 wt % of water. The liquid formulation can readily be used for foaming PVC and other thermoplastics.