Silica Dispersion Adhesive pH Adjustment for Sprayable Heat Resistance
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Solution Overview
Problem
Existing adhesive formulations based on polychloroprene dispersions face challenges such as high viscosity, short pot life, and low heat resistance, making them unsuitable for spraying and requiring the use of solvents or heating to achieve high heat resistance.
Innovation Solution
A process involving the adjustment of silicon dioxide dispersions to low pH values using strong or medium acids, allowing for the mixing with polychloroprene dispersions without coagulation, resulting in 1K formulations with high solids content and low pH, which can be sprayed and achieve high heat resistance without heating.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Temperature
If adhesive formulations based on polychloroprene dispersions and silica sols are used to achieve long open time and high heat resistance, then the formulations have high viscosity and are not suitable for processing by spraying
Solution Approach 1:
The patent applies parameter changes by adjusting the pH value of the adhesive formulation to the range of 8.5-9.5 through addition of bases (such as ammonia, hydroxides, or carbonates). This pH adjustment fundamentally changes the chemical environment, preventing coagulation of the polychloroprene dispersion while maintaining high solids content (30-60%), thereby achieving both heat resistance and sprayability without the need for solvents or heating
2Ease of operation
If solvent-free aqueous 1K formulations are used to achieve ease of operation for spraying, then the formulations show low heat resistance and are only used for foam-foam bonds
Solution Approach 1:
The patent employs composite materials by combining polychloroprene dispersion with inorganic fillers (such as silica, calcium carbonate, or aluminum oxide) in a synergistic formulation. The inorganic fillers enhance the heat resistance of the adhesive film while the polychloroprene provides adhesion. This composite approach allows the formulation to achieve both sprayability (through proper pH adjustment) and high heat resistance (through the thermal stability of inorganic fillers), breaking the limitation of low heat resistance in solvent-free aqueous formulations
3Stability of the object's composition
If the pH value of polychloroprene dispersions is lowered to achieve stability, then strong or medium acids cause immediate coagulation
Solution Approach 1:
The patent uses intermediaries (bases such as ammonia, hydroxides, or carbonates) to adjust the pH value to the optimal range of 8.5-9.5. These intermediaries act as mediators that neutralize excess acidity without causing coagulation, allowing the formulation to achieve both stability and prevent harmful coagulation effects. The intermediary substances buffer the pH and maintain the dispersion stability while enabling the use of inorganic fillers that require alkaline conditions
4Ease of operation
If organic solvents are added to achieve sprayability and destabilize the adhesive dispersion, then the formulations are only permitted under strict environmental conditions due to environmental regulations
Solution Approach 1:
The patent extracts and eliminates organic solvents from the adhesive formulation entirely, replacing them with an aqueous-based system. By removing the harmful organic solvent component and using only water, inorganic fillers, and pH adjusters, the formulation achieves sprayability through proper rheology control (pH 8.5-9.5) without any environmental restrictions. This extraction of the harmful substance allows unrestricted use while maintaining all functional properties
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 process enables the production of solvent-free, sprayable adhesive formulations with high initial strength, long pot life, and high heat resistance, suitable for bonding substrates without the need for heating, overcoming the limitations of existing technologies.
Implementation Method 1
the adjustment of silicon dioxide dispersions to low pH values using strong or medium acids, allowing for the mixing with polychloroprene dispersions without coagulation
Data Source
Figure 1
AI summary
The invention relates to aqueous compositions, particularly aqueous dispersions based on silicon dioxide, and to a method for the production and usage thereof as a component in the production of adhesive layers and for the bonding of the substrates coated on one side or both sides by spray application using the compositions.