Surface Action of Organosiloxane Modified Resin
Application of organosiloxane in coatings The adhesion of resin to the surface of the base material is usually negligible, especially when there is no chemical affinity between the polymer resin and the surface of the base material. Usually, manual peeling with mechanical force or automatic peeling at the edge of the facility are the manifestations of poor adhesion. In addition, wet vapor, acid or alkali often further accelerate the failure of adhesion. Organosiloxane is a kind of silane coupling agent. The general chemical formula is Y(CH2)nSiX3. Among them, n is 0-3; X is a hydrolyzable group which can react with inorganic substrates, mainly alkoxy group; Y is an organic group which can react with organic materials, mainly including vinyl, amino, epoxy, mercapto and other functional groups. Silicone is hydrolyzed by X-group to form silanol, which reacts with hydroxyl groups on the surface of inorganic substrates to form siloxane. Through Y-group, the purpose is to react with organic substances for chemical action. The inorganic substrates and organic substances are joined together to improve the performance of coatings and increase the bonding strength. It acts as a coupling.
There are three main ways in which organosiloxane can be used as adhesion promoter for coatings.

(1) As a base material treatment agent: usually add 3-10% organic siloxane and water and solvent mixed solvents cold-spelling mix, and then the substrate treatment, play the role of adhesion promoter;

(2) As reaction monomers: 0.5-5% organic siloxane is blended with conventional monomers of synthetic resins, and then copolymerization is carried out, so that the structure of the resins can be incorporated into the siloxane structure. Siloxane acts as crosslinking agent, promotes the adhesion of the resins to the matrix, improves the mechanical properties and water resistance of the resins, etc.

(3) As a post-additive, siloxane monomer is added to the resin according to the solid content of the resin 0.2-5%. After about 12 hours of induction period, the resin is mixed with other additives and fillers to prepare the coating, so as to enhance the adhesion of the coating to the substrate. Some examples of specific applications at present include: as a substrate treatment agent, aminosiloxane is blended with mixed solvents such as water, isopropanol, butanol and butyl fibrinolytic agent. Among them, the amount of water is determined by the amount of water required for pre-hydrolysis of siloxane, and the thickness of the cleaned substrate surface is obtained by spraying, dipping or brushing.- 3 micron coating can dry the surface and coat the surface in 24 hours to enhance the adhesion of the coating. As the application of polymer copolymerization modification monomer, vinyl siloxane is pre-emulsified with conventional acrylate monomer, and then copolymerization is initiated by initiator to obtain Siloxane-modified propylene. In the process of drying film formation, siloxane will undergo hydrolysis and condensation, so that the cross-linking structure of Si-O-Si can be obtained through condensation between silanol and cross-linking monomer. Or in the process of preparing polyurethane, siloxane containing amino group or epoxy group is used to end-capping reaction with isocyanate group, and siloxane is introduced into the chain of polyurethane to modify the monomer function; as the application of post-additive additive, siloxane containing amino group is added into the epoxy resin after preparation, and amino group and ring are used to modify the monomer function. Siloxane group was introduced into the grafting reaction of oxygen group, and then a small amount of water mixed solvent was introduced. Siloxane was hydrolyzed and condensated to obtain the designed structure. Coatings with improved properties were prepared by grinding and dispersing additives and fillers. BNK-D6040 (Adhesion Promoter) of case [Merikan].
BNK Auxiliaries Transferred from USA