why nylon fabric and liquid silicone rubber are difficult to bond?
The main reasons why nylon fabric and liquid silicone rubber are difficult to bond are as follows:
1. Surface energy difference
Nylon surface energy is low: Nylon fabric has low surface energy, and liquid silicone rubber is difficult to wet and spread, resulting in bonding difficulties.
Silicone rubber surface energy is low: Liquid silicone rubber also has low surface energy, which further increases the difficulty of bonding between the two.
2. Chemical structure difference
Polarity difference: Nylon is a polar material, while liquid silicone rubber is a non-polar material. The chemical compatibility between the two is poor, and it is difficult to form a strong chemical bond.
Low reactivity: Liquid silicone rubber has low reactivity and is difficult to react chemically with the functional groups on the surface of nylon.
3. Surface contamination
Grease and impurities: The surface of nylon fabric may contain grease, release agent or other impurities. These contaminants will hinder the direct contact between liquid silicone rubber and nylon, affecting the bonding effect.
4. Smooth surface
Smooth surface: The surface of nylon fabric is usually smooth and lacks sufficient roughness, so it is difficult for liquid silicone rubber to achieve a firm bond through mechanical bite.
5. Difference in thermal expansion coefficient
Mismatched thermal expansion coefficient: The thermal expansion coefficients of nylon and liquid silicone rubber are quite different, which easily generates stress when the temperature changes, resulting in failure of the bonding interface.
Solution
In order to improve the bonding strength between nylon fabric and liquid silicone rubber, the following measures can be taken:
Surface treatment
Cleaning surface: Use solvents or detergents to thoroughly clean the surface of nylon fabric to remove grease and impurities.
Surface activation: Improve the polarity and reactivity of the nylon surface through methods such as plasma treatment, corona treatment or chemical treatment.
Use primer
Apply primer: Apply a special primer on the surface of nylon fabric to increase surface energy and improve the wettability and adhesion of liquid silicone rubber.
Adjust the silicone rubber formula
Add adhesion promoter: Add adhesion promoter to liquid silicone rubber to improve its bonding performance with nylon.
Choose special silicone rubber: Use liquid silicone rubber specifically for nylon materials to improve the bonding effect.
Mechanical treatment
Increase surface roughness: Increase the roughness of the nylon fabric surface through methods such as grinding or sandblasting to improve the mechanical bite force.
Optimize process parameters
Control curing conditions: Ensure that the liquid silicone rubber is cured at the appropriate temperature and time to avoid insufficient or over-curing.