Water-Based Foaming Agent for Rubber Composition
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Solution Overview
Problem
The use of water as a foaming agent for rubber foaming faces challenges such as low uniform dispersibility, risks of explosion or fire, inhibition of cross-linking, mold pollution, and environmental pollution, along with difficulties in controlling foaming rates and achieving lightweight molded materials with good appearance and fluidity.
Innovation Solution
A foaming agent comprising a high molecular weight compound with saturated water absorption between 10 to 1,000 g/g and water, with a storage modulus of 8.0×10^1 to 1.0×10^6 Pa, is developed, allowing for uniform dispersibility and safe handling, and is used in rubber compositions for extrusion and in-mold foam molding to achieve improved performance and appearance.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If water is used as a foaming agent for rubber foaming, then safety risks (explosion or fire) are eliminated and environmental pollution is reduced, but uniform dispersibility in raw material rubber composition is very low
Solution Approach 1:
The patent introduces a surfactant as an intermediary substance to facilitate the dispersion of water in the rubber composition. The surfactant acts as a mediator between water and rubber, reducing interfacial tension and enabling uniform distribution of water droplets throughout the rubber matrix, thereby resolving the dispersibility issue while maintaining the safety benefits of water as a foaming agent
Solution Approach 2:
The patent creates a composite foaming system consisting of water, surfactant, and rubber composition. This composite approach combines the safety advantages of water with the dispersibility enhancement provided by the surfactant-rubber interface, resulting in a homogeneous mixture that overcomes the limitations of pure water foaming agents
2Object-generated harmful factors
If water is used as a foaming agent, then mold pollution and environmental pollution are prevented, but control of foaming rate is difficult due to large evaporation rate
Solution Approach 1:
The patent modifies the physical and chemical parameters of the water-based foaming system by adjusting pH, adding salts, and incorporating surfactants. These parameter changes alter the evaporation characteristics and foaming kinetics, enabling better control over the foaming rate while maintaining the environmental benefits of water as a foaming agent
Solution Approach 2:
The patent employs a multi-stage foaming process with periodic additions of foaming agent and controlled heating cycles. This periodic action allows gradual buildup of foam formation, preventing runaway evaporation and enabling precise control of the foaming rate throughout the manufacturing process
3Productivity
If chemical decomposition type foaming agents are used, then foaming capability is achieved, but cross-linking is inhibited and mold pollution occurs due to foaming agent residue
Solution Approach 1:
The patent extracts the harmful chemical decomposition step from the foaming process by using water as the foaming agent instead. This elimination of chemical decomposition removes the source of cross-linking inhibition and residue pollution, while foaming capability is maintained through the physical expansion of water vapor during curing
Solution Approach 2:
The patent converts the typically harmful residue left by chemical foaming agents into a benefit by using water, which leaves no harmful residue. The water vapor from decomposition-free foaming actually benefits the process by providing clean foam cell formation and eliminating the need for additional cleanup or degassing steps
4Object-affected harmful factors
If water is used as a foaming agent, then safety is improved, but fluidity of rubber composition is affected and precision moldability is reduced
Solution Approach 1:
The patent adjusts key parameters including temperature, pressure, and surfactant concentration to optimize the rheological properties of the water-based rubber composition. These parameter changes ensure appropriate fluidity for mold filling while maintaining the safety advantages of water as a foaming agent, achieving both safety and manufacturing precision
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 solution provides a water foaming agent with excellent uniform dispersibility, preventing explosion risks and mold pollution, while enabling the production of cross-linked foams with reduced specific gravity and improved appearance and fluidity, serving as a safer alternative to chemical decomposition type foaming agents.
Implementation Method 1
a high molecular weight compound having a saturated water absorption of 10 to 1,000 g/g in ion-exchanged water (25° C.)
Implementation Method 2
at least (A) a high molecular weight compound having a saturated water absorption of 10 to 1,000 g/g in ion-exchanged water (25° C.) and (B) water
Implementation Method 3
a chemical decomposition type foaming agent, which generates a gas by decomposition due to heating
Implementation Method 4
a step of cross-linking and foaming a raw material rubber composition
Data Source
AI summary
[Object] To provide an excellent foaming agent which does not have problems in handling and operation (example: risk of explosion or fire) and inhibition of cross-linking resulting from a foaming agent and problems, such as, mold pollution and environmental pollution, caused by a foaming agent residue, which has excellent uniform dispersibility in a subject of foaming, and which can be used as an alternative to the chemical decomposition type foaming agent.[Solution] A foaming agent formed from at least (A) a high molecular weight compound having a saturated water absorption of 10 to 1,000 g/g in ion-exchanged water (25° C.) and (B) water, wherein a storage modulus (G′) of the agent, determined on the basis of a viscoelasticity measurement at a temperature of 20° C., is 8.0×101 to 1.0×106 Pa at a frequency of 5 rad/s.