Synonyms: Stannous octoate, Stannous octoate, DABCO T-9, Kosmos 29, Addocat SO, Niax D-19, PC CAT T9, Borchi Kat 28, CAS 301-10-0, dabco t catalyst, dabco t polyurethane catalyst
Stannous octoate is a basic catalyst used in the production of polyurethane foam, room temperature curing silicone rubber, polyurethane rubber, and polyurethane coatings. It is extremely chemically unstable and highly susceptible to oxidation.
Dipole effect: A contact potential is generated between the organic coating and the substrate, forming an electric double layer, and generating a dipole force. For example, the acid-modified water-based resin with ammonia as the cation forms a positive charge on its surface, which can form a good adhesion on the metal surface with a negative charge.
The increase in adhesion can be explained by the force between the interfaces. However, the effect of the adhesion promoter is not achieved by a certain force alone. Sometimes multiple forces exist at the same time, even like the adhesion of certain plastics. It also benefits from the dissolution and wetting of the plastic by the solvent to a certain extent, so that the base material (containing the adhesion promoter) and the plastic polymer wax form a swollen and entangled adhesion layer to form an adhesion promotion. The following introduces various adhesion promoters to understand specific applications and performance characteristics.
Types and characteristics of adhesion promoters
A silane coupling agent
Silane is an organosilicon compound monomer with the general chemical formula R—SiX, where X is a hydrolyzable organic functional group, generally methoxy; R is a non-hydrolyzable organic functional group, such as amino, Diamino group, methacrylate group, styrene/amino cationic group, epoxy group, vinyl group, chlorinated alkyl group, etc. The functional groups and chemical structures of typical commercial silane coupling agents.
The adhesion promotion effect of the silane coupling agent has different promotion effects for different inorganic substrates, and not all kinds of inorganic substrates have very excellent adhesion promotion effects. Generally, silane coupling agents can form covalent bonds on absorbent inorganic surfaces and elements, such as glass containing hydrocarbon groups, quartz/silicon, aluminum, zinc, and iron. Magnesium oxide, kaolin, talc and titanium dioxide can form covalent bonds. The reactivity of the silane coupling agent is medium. For non-absorbent inorganic surfaces, such as graphite, boron, alkali metal and alkaline earth metal oxides, they cannot form covalent bonds with silanol, and the adhesion strength is relatively the worst L4.57.
A silane coupling agent is added to the coating. After the coating is applied, the silane migrates to the interface of the substrate. When it encounters the moisture on the inorganic surface, it can hydrolyze to form a silanol group, and then form a hydrogen bond or shrink Synthesize Si-OM (M stands for metal, glass and other inorganic surfaces) covalent bond; and the R organic functional group on the silane reacts with the coating resin or curing agent, bonds or forms a tangled entanglement, so as to achieve the role of adhesion promotion At the same time, the silanol groups between the silane molecules will also condense with the coating film to form a network structure.
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