TED rubber-catalyzed solid amine initiator for polyurethane coatings

A non-flavored solid amine, abbreviated as TED, anhydrous triethylenediamine is flammable crystals, very easy to deliquescence, easy to rise at room temperature. Melting point 158, boiling point 174, flash point 50 (open cup). Soluble in water, acetone, benzene and ethanol, soluble in pentane, alkane, heptane and other straight-chain hydrocarbons; can absorb CO2 in the air and yellowing. It is weakly alkaline.

The mechanical bonding force of coatings on substrates with different surface structures
Resin base materials, plasticizers, wetting agents, surfactants, leveling agents and even solvents are all closely related to adhesion. However, a large part of this definition only talks about the basic requirements of adhesion, that is, the coating fluid and the coating film must be able to wet the substrate or primer. You can obtain this information in Chapters 2 and 8 of this book. Do not go into details. The following will start with the interface force, and then introduce the various adhesion promoters that can provide these forces between the interfaces.

Interface force
There are atomic and molecular forces between the paint film/adhesive and the substrate, including covalent bonds, ionic bonds, hydrogen bonds and van der Waals attraction. If the distance between the two contact planes is as small as nanometers or less, the van der Waals gravitational force can reach 9.8~98MPa, but it is almost impossible to achieve in actual painting and contact. Moreover, van der Waals gravity belongs to physical adsorption, which is easily replaced by water molecules in the air.

Therefore, when there is an adhesion problem, the substrate can be polished to reduce the viscosity of the coating, or increase the curing temperature, or make the substrate form a rough surface. It is best to form a bonding force between the coating film and the substrate to obtain The best force. If the base material of the coating film cannot produce bonding force, a primer or adhesion promoter that can adhere to the substrate can be used to make the primer, and then the coating can be applied. The most convenient method is to add an adhesion promoter to the coating to promote the adhesion between the base material and the substrate of the coating film, and to obtain the coating film with the best adhesion. Table 21-2 shows various forces between interfaces.

Various chemical bonds include covalent bonds, ionic bonds, hydrogen bonds, etc. For example, when the base material has hydrocarbon groups, carboxyl groups and amino groups, it is easy to hydrogen bond with the oxygen atoms or hydroxyl groups of the substrate, while the epoxy groups It can interact with aluminum surface to a certain degree. These forces are very large, several times, tens of times or even hundreds of times that of Van der Waals’s gravity. Silane coupling agents, titanates and polymer adhesion promoters can promote the adhesion of some metals and inorganic substrates, which is based on this effect.

Diffusion force: When the solubility parameters of the molecules of the coating base material or adhesion promoter and the polymer substrate are close to each other, and both are above the glass transition temperature, the base material or adhesion will be promoted due to the Brownian motion of the molecules or chain segments The molecules at the interface between the agent and the polymer substrate diffuse each other to form a force that promotes adhesion. Typical examples are the adhesion of acrylic paints to plastics (ABS, PC), and chlorinated polyolefin adhesion promoters to improve the adhesion of paints to PP, PP/EPDM.