Bectron® PK 4340 is a one-component resin system which cures to form a soft polyurethane duroplastic. It comprises a liquid polyol system with a dispersed solid encapsulated polyisocyanate and a pigment combination selected to provide controlled rheology including excellent thixotropic properties. Heating the resin releases the encapsulated polyiso- cyanate resulting in a polyaddition reaction to give a resistant duroplastic cured material.
In contrast to the usual 2 component resin systems Bectron® PK 4340 is ready to use and distinguished by excellent properties and especially good environ- mental compatibility.
APPLICATIONS
- The cured Bectron® PK 4340 is a soft duroplastic suitable for vibration protection of delicate compo- nents.
- Bectron® PK 4340 is therefore well suited for the partial or selective coating of SMD and other compo- nents groups on printed circuit boards and ceramic substrates. The rapid increase of viscosity at low shear allows small areas of components to be pro- tected individually.
- Bectron® PK 4340 can be applied as a dam around an area requiring thicker coating to be filled by a low- er viscosity grade such as PK 4342.
Properties of components as supplied
|
Property |
Condition |
Value |
Unit |
|
Viscosity, DIN 53019 |
D=15 s-1, 23°C |
9.500 ± 1.500 |
mPas |
|
Density, DIN EN ISO 2811-2 |
23°C |
1,23 ± 0,02 |
g/cm³ |
|
Shelf life |
23°C |
6 |
months |
Pot-life, gel-time, curing conditions
|
Property |
Value |
Value |
Unit |
|
Temperature |
80 |
90 |
°C |
|
Gel-time |
5 ± 2 |
|
min |
|
Curing |
65 ± 5 |
30 ± 5 |
min |
Thermal properties of cured compound
|
Property |
Condition |
Value |
Unit |
|
Coefficient of thermal expansion, Beck Test M 56 |
-20°C to + 90°C |
200·10-6 |
K-1 |
|
Thermal conductivity, DIN 52616 |
23°C |
0,18 ± 0,02 |
W/mK |
