Product information
VESTAGON
BF 1321
CROSSLINKING AGENT FOR POLYURETHANE POWDER COATINGS
GENERAL DESCRIPTION
VESTAGON
BF 1321 is a polyisocyanate adduct used in combination with hydroxy functional resins.
Because of an internal blocking mechanism, the product retains its processing stability up to the splitting
temperature of approximately 160 °C. The crosslinker is delivered in the form of fine granules.
SPECIFICATION
Property Value Unit Test method
NCO content (total) 14.0 - 15.5 % wt according to DIN EN ISO 11 909
NCO content (free) ≤ 0,3 % wt DIN EN ISO 11 909
Glass transition temperature 65 - 82 °C DSC
Colour index ≤ 600 - DIN EN ISO 6271
TYPICAL PROPERTIES
Property Value Unit Test method
NCO-equivalent ~ 285 g/Eq -
Density 1.12 g/cm
3
DIN EN ISO 1183
Bulk density ~ 570 kg/m
3
DIN EN ISO 60
Melting range 110 - 130 °C DIN EN ISO 3146
Flashpoint 230 °C DIN EN ISO 2592
Ignition temperature 390 °C DIN 51 794
APPLICATIONS
Numerous OH-terminated polyester and acrylics can be used to achieve weather-resistant decorative
powder coatings with excellent physical properties. These polyols have a determining influence on the
performance of the coating.
Evonik Operations | VESTAGON BF 1321 e | Page 1/3 | 4/17/2023
FORMULATIONS
Crosslinker and polyester are used in equivalent amounts. Empirically determined “under indexing” (up to
NCO:OH = 0.8 : 1) yields economical coatings which exhibit excellent physical properties meeting the
required performance profile.
EXAMPLES OF FORMULATION FOR BINDER COMBINATIONS
Crosslinking ratio (NCO:OH) 1 : 1 0.8 : 1
VESTAGON BF 1321 14 21 12 19 parts
Polyol (OH number 30) 86 - 88 - parts
Polyol (OH number 50) - 79 - 81 parts
Up to 1 % by weight degasser is often used in pigmented powder coatings to minimize surface
imperfections.
The use of a catalyst to accelerate the formation of urethane bonds is recommended. Bismuthcarboxylates
(e. g. KOSMOS MB 16) has been proven to be a useful accelerator. The maximum suggested use level is
0.20 % by weight based on the total formulation.
CURING
The curing temperature for PUR powder coatings based on VESTAGON
BF 1321 lies above the splitting
temperature of about 160 °C. A prerequisite for good physical properties of a coating is sufficient curing in
the range of 170 °C, 20 minutes up to 210 °C, 5 minutes total oven time, according to the following
standard procedures.
⋅ Premixing: MTI-Mixer 2' - 500 rpm
⋅ Application: Manual spray gun 80 kV; steel panels 0.8 mm
⋅ Curing: Air-circulated Heraeus oven; coating thickness 55-75 µm
EXTRUSION CONDITIONS
We recommend the extrusion conditions as follows:
Buss PLK 46
Barrel temperatures: Zone 1 + 2 - 120 °C
Screw temperature: cooled
Screw speed: 160 r.p.m.
Werner & Pfleiderer
Barrel temperatures: Zone 1+2 - 90 °C
Screw speed: 250 r.p.m.
The extrusion temperature must be selected to ensure that a mass temperature of minimum 130 °C is
maintained. Otherwise, inadequate dispersion may result in reduced gloss and mechanical properties of
the coatings.
Evonik Operations | VESTAGON BF 1321 e | Page 2/3 | 4/17/2023