How to solvate polyvinyl butyral resin (PVB) and what should be paid attention to in processing?

When mixed solvent is used, the dissolving step is as below.

Firstly we can add and even stir the aromatic solvent (such as xylene, toluene, etc.) or ester solvent (such as n-butyl acetate, ethyl acetate, etc.). Then add PVB resin powder slowly during stirring. After the PVB resin is dispersing and swelling, we can add alcohol solvents (such as n-butanol, ethanol, etc.). At this time, the dissolution time can be shortened by heating.

this dissolution method can avoid the formation of lump-like (Lump) PVB (because the dissolution time will be several times after the lump-like PVB is formed), so the dissolution speed can be accelerated. Generally, the ratio of aromatic and alcohol solvents is 60/40 to 40/60 (weight ratio), and a PVB solution with lower viscosity can be prepared. The solvent composition contains 2-3wt% of water, which can improve the hydrogen bond strength of alcohol solvent (Hydrogen bonding) and help the solubility of PVB.

Although PVB resin is a thermoplastic, it has almost no processability before adding a plasticizer, but its processability is very easy after adding a plasticizer. The general purpose of coatings and adhesives is to change the resin properties by adding plasticizers to meet the application requirements, such as film flexibility, lowering the Tg point of the resin, lowering the temperature of heat sealing, maintaining low temperature flexibility, etc.

PVB is compatible with a variety of resins, such as phenolic resins, epoxy resins, alkyd resins and melamine resins. B-08SY, B-06SY and B-05SY with higher acetal degree can be mixed with nitrocellulose in any ratio. PVB and alkyd resins are partially compatible. General PVB is compatible with low molecular weight epoxy resin, while high molecular weight epoxy resin needs to choose PVB with high acetal degree to be compatible with each other.