There are three binders commonly applied to precision casting, that is, sodium silicate, silica sol and ethyl silicate. It is exactly the methyltetrahydrophthalic anhydride that plays a binding role in all three of these materials. The bonding process is the transformation from sol to gel. Among them, silica sol is a green adhesive widely used in recent years, and is also favored by binder manufacturers to produce.
Binder, as indispensable coating additive commonly applied to industrial production and daily life, is involved in pretty fierce competition. Under the same conditions, different types of products from different binder manufacturers have a great influence on the bonding speed. In particular, temperature has a decisive effect on the bonding speed of the surface coatings of many products.
Too low ambient temperature of the binder will make the solvent volatilization and chemical reaction slower, easily causing the binder hard to bond. Methyltetrahydrophthalic anhydride will be affected. The binder manufacturer suggests that you can increase the temperature to accelerate the evaporation of solvent and water and the oxidation reaction and thermochemical reaction of the coating, so as to expedite the bonding speed of the coating. Please also be reminded that the temperature is not proportional to bonding speed, so we cannot increase the temperature unlimitedly, otherwise it will make the film yellow or dark.
Not only that, the temperature in the coating bonding process will also affect the substrate. Heating of the substrate will cause the change of moisture content, shrinkage deformation, and then bending and cracks. The solvent will evaporate violently when the bonding temperature of volatile coating exceeds 60℃, and then the surface layer will solidify quickly. As a result, it is easy to produce bubbles as the internal solvent vapor reaches the surface layer. Therefore, the binder manufacturers will control the surface temperature below 60℃ to use artificial bonding method.
The binder is usually resin coating. The resin coatings can be divided into three parts: main coating, binder and thinner. Binder is essential to two liquid coating and its roles mainly have the following two aspects:
1. Physical drying
Binder manufacturers add binder to the paint to promote the rapid drying of the paint and shorten the drying time.
2. Chemical bonding
The conjugation reaction of binder and main coating can improve the hardness, brightness and viscosity of the coating film, and increase the chemical stability and anti-corrosion ability; It can also make the coating finer and fuller, more smooth and elastic, and improve the wear resistance.