The reaction liquid is filtered through plate and frame pressure to obtain lithopone in the form of a filter cake with a moisture content of no more than 45%. It is then roasted in a drying furnace to change the crystal form of lithopone, and is then pickled with sulfuric acid at a temperature of 80°C. Finally, it is washed with water, reinforced with colorants, filtered, dried and ground into powder.

Polyvinyl Butyral Resin (PVB) is a solvent Resin synthesized by the acetal reaction of Polyvinyl Alcohol (PVA) and butyraldehyde in contact with coal.

Because Pvb Resin itself contains a lot of hydroxyl groups, it can bridge with some thermosetting resins to improve the properties of chemicals and film hardness.

Because PVB resin has the above excellent characteristics, it is widely used in adhesive safety glass intermediate film of automobile and building, rust cutting primer, baking paint, wood paint, printing ink, adhesive of electronic ceramics and printed circuit board, adhesive between metal and metal, between metal and plastic, modifier of hot-melt adhesive, iron dimension waterproof processing of textile, etc. A variety of new industrial applications are also continuously developed and applied.

The general characteristics of PVB are as follows:

The appearance of polyvinyl butyral (PVB) resin is white spherical porous particles or powder, and its specific gravity is 1:1; However, the filling density is only 0.20 ~ 0.35g/ml.

Thermal properties

The glass transfer temperature (TG) of polyvinyl butyral (PVB) resin ranges from 50 ℃ of low degree of recombination to 90 ℃ of high degree of recombination; The glass transfer temperature can also be adjusted by adding an appropriate amount of Plasticizer to reduce it below 10 ℃.

Mechanical properties

The coating of polyvinyl butyral (PVB) resin has good water resistance, water resistance and oil resistance (it is resistant to aliphatic, mineral, animal and vegetable oils, but not to sesame oil). PVB is widely used in printing inks and coatings because it contains high hydroxyl groups and has good dispersibility to pigments.

In addition, its chemical structure contains both hydrophobic acetal and acetic ACID groups and hydrophilic hydroxyl groups, so PVB has good adhesion to glass, metal, plastic, leather and wood.

Chemical reaction

Any chemical that can react with secondary alcohol will also react with PVB. Therefore, in many applications of PVB, it is often used with thermosetting resin to bridge and harden with the hydroxyl group of PVB, so as to achieve the characteristics of chemical resistance, solvent resistance and water resistance.

Of course, films with different characteristics (such as hardness, toughness, impact resistance, etc.) can be prepared according to different types of thermosetting resin and different mixing ratio with PVB.

Safety properties