MagShield® S NB10 in Polypropylene Formulations

MagShield S NB10 magnesium hydroxide was utilized at 60% by weight in a polypropylene formulation along with the addition of 5% talc. The compound was UL94 V(0) for 1/8" (3.2 mm) and 1/16" (1.6 mm) thicknesses.

Formulation  
MagShield S NB10
60% by weight
Talc, MicroTuff AGD 609
5%
Polypropylene (MFI 22 @ 230 C)
33%
PolyAd Preblend MM1252-25*
1%
Calcium Stearate 1%

All Ingredients Fed as a Preblend

Extruder Conditions  
Extruder                                                          
40 mm Leistritz
Extruder RPM                                     170
Temperature Profile
T1                                                                    213°C
T2                                                                    211°C
T3                                                                    211°C
T4                                                                    211°C
T5                                                                    210°C
T6                                                                    210°C
T7                                                                    210°C
T8                                                                    211°C
Die                                                                  210°C

Good venting and vacuum (at least 900 millibars) near the die is recommended to obtain a high quality extrudate.

UL94 Results    
Thickness
1/8" (3.2 mm) 1/16" (1.6 mm)
UL94 Rating V(0) V(0)
Average Afterflame Time per Sample 1 second 2.2 seconds
Average Afterflame + Afterglow
Time per Sample, Average
3.6 seconds 6.0 seconds
Afterflame/Afterglow to Clamp None None
Cotton Ignition None None

MagShield S NB10 can be used to achieve a UL94 V(0) compound at 60% loading in polypropylene (PP) at both 1/8" (3.2 mm) and 1/16" (1.6 mm) thicknesses. The main difficulty with achieving a UL94 V(0) rating on thin samples (1/16") is dripping of the plastic. The presence of 5% talc in the formulation helped to prevent dripping which allowed the MagShield to effectively retard the flame and prevent burning of the plastic.

If a high whiteness, high brightness compound is desired, 1-2% TiO2 may be added to the formulation.

Use of an antioxidant, such as the MM1252-25 shown in our formulation, is necessary for good color characteristics.

See MagShield data sheets for complete descriptions of products. Other formulations for other polymers and FR standards are available from Martin Marietta Magnesia Specialties’ Technical Service. Please call 800-648-7400 (inside the U.S.) or +1-410-780-5500. Or, email us with your questions.

*PolyAd Preblend MM1252-25, available from Ciba Specialty Chemicals, is:
TM 25% Irganox 1010
TM 20% Irganox 168
TM 25% Irganox MD 1024
TM 30% Irganox PS-802
Irganox is a Trademark of Ciba Specialty Chemicals