What Is Caulking?
Caulking is a product used to fill cracks and gaps in structures caused by impact, fatigue, or age-related deterioration, to maintain waterproofing performance and strength.
Caulking is a type of adhesive that can be injected into cracks or holes to expose them to air, or mixed with the main and hardening agents to fill holes and repair strength. However, there are also many products that are designed to be flexible after curing rather than for adhesive purposes, assuming that holes will be drilled or painted after use.
Applications of Caulking
Caulking is widely used for repairing buildings and machinery.
Cracks and design gaps in concrete, plastic, metal, and other materials require immediate repair because they cause aesthetic damage, loss of strength, leakage, and other problems.
Caulking can be injected into the target surface to restore lost aesthetics and functionality as a post-repair measure, and also to prevent the progression of deterioration due to the intrusion of moisture and other deterioration factors.
For surfaces with more advanced deterioration, it may be necessary to seal the surface only, without injecting into the pore spaces.
Principle of Caulking
Caulking is based on the principle that silicone resin, epoxy resin, etc. react with moisture in the air or polyamine or polyamide to cure.
In the case of silicone resin, there are alkoxy groups on the surface, which hydrolyze with moisture in the environment and cross-link to form a rubber elastic body. In the case of epoxy resins, the epoxy groups in the molecule react with polyamine and polyamide to create a cross-linked structure. However, because strong amide bonds are created in the molecule, the adhesive strength becomes stronger and harder.
When strength is required in caulking for repairing vehicles and buildings, strong bonds such as epoxy resins are suitable. However, they are not suitable for use on plastic surfaces or for post-repair processing. If adhesion to the surface or the use of soft materials is required, silicone resins with excellent elasticity are suitable.
Modified silicone resins, in which some of the methyl groups in the molecule are replaced with functional groups, are an improved version of silicone resin.