English Name: Stannous octoate
Chemical formula: C16H30O4Sn
Molecular weight: 405.1
CAS Registry Number: 301-10-0
Stannous main content: 28+/-0.50%
The three processes of silane coupling agent to improve adhesion:
① The silanol group is formed after the silane is hydrolyzed.
②The silanol group forms hydrogen bonds or covalent bonds with inorganic substrates such as metals and glass:
Metal glass, etc.
③The organic functional group on the silanol group reacts with the resin or curing agent:
Since the silane coupling agent needs to complete the above three processes in order to achieve the effect of improving adhesion and the resulting increase in water resistance, moisture resistance and salt spray resistance of the coating film, the choice of silane coupling agent must follow the following Point principle,
①The resin/curing agent has reactive groups that can react with the R organofunctional group on the silane. For thermoplastic resin base materials, silanes with similar properties and polarity should be selected to make the resin base material and the organic functional groups of the silane easily entangled. Entangled.
②The reaction rate of the organic functional group of the silane and the resin or curing agent must be equivalent to the reaction rate of the resin/curing agent in the coating to ensure dyneon ptfe fine powder that the functional group on the silane can react and bond to the coating film base during the crosslinking process of the resin and the curing agent. On the material.
③When the silane coupling agent is used as an additive, it needs to maintain its stability and sufficient migration force, so that the silane coupling agent can migrate to the interface between the substrate and the coating film, and play the role of coupling and promoting adhesion. It is usually slightly acidic. The stability of hydrolysis can be maintained in the environment.
After proper selection of the silane coupling agent, after the completion of the hydrolysis and the formation of a hydrogen bond or covalent bond with the substrate, and a strong chemical bond with the resin or curing agent in the base material, the silane and the base material can be in the substrate The interface layer interacts with each other to form an interpenetrating network structure, which enhances the cohesion and hydrolysis resistance stability, so that the stress can be transferred from the high modulus substrate to the low modulus paint base, so as to improve adhesion and hydrolysis resistance stability.
When the silane-added coating film is immersed in water, the bond formed will be broken and reconnected to restore the adhesion. Since the longer the immersion in water, the higher the degree of bond hydrolysis and disconnection. The actual bond disconnection and reconnection and the required time are related to the coupling strength and chemical bonding of the coupling agent.
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