27 июля, 2015 
Malyar The most common type of additive used in TPA formulations is the cellulose ester, in particular cellulose acetate butyrate (CAB). This can confer a range of properties to coatings, including flow control, reflow in automotive top coats and the improvement of cold check resistance.
Manufacturers of CAB, such as Eastman Chemical, offer a range of esters formulated for the diverse range of uses.
The main formulating parameters are:
• Acetyl/Butyryl ratio
• Hydroxyl value
• Molecular weight
High butyrate content resins (45-53%) exhibit better general compatibility and when combined with lower molecular weights (15000-30000) result in products which are used mainly as flow additives.
CAB’s with less than 40% butyryl and higher acetyl contents (14%) and molecular weights as high as 70000 are tough products, which improve the mechanical strength of the coating. These grades tend to be used with MMA thermoplastic acrylics in automotive OEM (original equipment manufacture) or repair applications.
Levels of CAB used in acrylic lacquer formulations fall between 1 % (flow additives) and 10% based on solid resin content.
Other additives used to aid thermoplastic acrylic paint formulation are pigment wetting agents, and silicone slip and flow aids.
Опубликовано в рубрике 