Views: 4 Author: Site Editor Publish Time: 2025-04-09 Origin: Site
Improving the moisture resistance of adhesives and sealants requires comprehensive improvements from various aspects such as material selection, formulation design, and process optimization. The following are the specific strategies and steps:
Hydrolysis-resistant matrix material
Silicone materials: naturally hydrophobic and suitable for high humidity environments (such as bathroom sealant).
Modified epoxy resin: Enhance hydrolysis resistance by introducing hydrophobic groups such as fluorination or silicone modification.
Polyurethane modification: Aliphatic isocyanate is used to replace aromatics, which has stronger hydrolysis resistance.
Filler reinforcement
Hydrophobic filler: Add silica, mica or carbon nanotubes to form a physical barrier layer.
Nanomaterials: such as graphene or organic clay, increase the tortuousness of the moisture permeability path.
Coupling agent application
Silane coupling agents (such as KH-550, KH-560): Enhance interfacial adhesion and form a hydrophobic film layer.
Titanate coupling agent: Improves the compatibility of polar surfaces with resins and reduces moisture erosion.
Anti-moisture additives
Waterproofing agent: silicone oil or fluorocarbon compound, reducing surface energy.
Hygroscopic inhibitors: calcium oxide or molecular sieve, which locally absorbs permeable moisture.
Full curing: Ensure temperature and humidity conditions (such as epoxy resin needs to be cured after heating) to avoid residues of unreacted monomers.
Deep crosslinking: Use high crosslinking curing agents (such as acid anhydride curing agents) to reduce molecular gaps.
Substrate pretreatment: grinding, plasma treatment or chemical cleaning to remove contaminants.
Primer: Coat primer containing hydrophobic ingredients (such as silane primer) to enhance the interface barrier.
Multi-layer protection: First apply high adhesion adhesive, and the outer layer is covered with elastic sealant (such as polysulfide sealant).
Drainage design: Design diversion grooves at the joints to avoid long-term contact between accumulated water.
Humid and heat aging test: refer to ASTM D2247 or ISO 9142 to simulate long-term humid environments.
Tensile shear test: Evaluate the retention rate of bonding strength under humidity.
Chemical modification: The main chain introduces hydrophobic groups (such as fluorine) or reduces hydrophilic groups (such as hydroxyl).
Economic balance: Nanofillers are costly and can be used locally in key areas; natural mineral fillers (talc powder) reduce costs.
Performance balance: Avoid excessive crosslinking to cause brittle cracks, and requires both flexibility and moisture resistance.
Environmental protection: Choose non-toxic and harmless additives (such as environmentally friendly silane coupling agents).
Through the above method system optimization, the durability of adhesives and sealants in humid environments can be significantly improved, and is suitable for many fields such as construction, automobiles, and electronic packaging.
