Meishen
Introduction
Of The Effect Of Magnesium Hydroxide On Flame Retardant
Magnesium
hydroxide is converted between 340? and 490?,
and its heat absorption energy is 187cal/g.
The
average initial conversion temperature of magnesium hydroxide is much higher
than that of alumina hydrate. It has good heat stability, excellent flame
retardant grade and smoke removal effect. It is very suitable for the
production and processing of polyolefin plastic products with higher average
temperature.
When
Mg(OH)2 is applied to PP (the addition amount is more than 50%), it has an
excellent flame retardant level effect. When Mg(OH)2 is applied to PE, its
flame retardant level effect is stronger than AI(OH)3.
This
is due to magnesium hydroxide in the ignition not only achieve dehydration
chemical reaction, but also on the polymer has the corresponding carbonization
effect to produce a layer of protective layer, with a flame-retardant
efficiency.
Under
the same amount of addition, different proportions of aluminum hydroxide and
magnesium hydroxide have no significant difference in the efficacy of flame
retardancy grade, but the efficacy of the two combined applications is better
than that of the direct application. Although both of them require dehydration
chemical reactions, there are differences in the average conversion temperature
and endothermic energy.
Magnesium
hydroxide requires a higher average temperature to dehydrate and is carbonized
at the same time.
The
heat absorption of magnesium hydroxide is relatively small, because the effect
of controlling the average temperature rise of the material is not as good as
that of aluminum hydroxide, the two applications can be combined to fill each
other, its flame retardant grade is better than the direct application effect.
Magnesium
hydroxide has a good smoke suppression effect. The smoking duration of PP
specimens containing Mg(OH)2 was significantly delayed at the beginning, and
the maximum smoking volume and the smoking volume after 4min were much lower
than those of PP specimens containing halide /Sb2O3.
For
this reason,Mg(OH)2 is an efficient smoke-removing filler for PP under the
standard of moderate dosage.
Poor
acid resistance of Mg(OH)2, it will dissolve rapidly in the acid, and it is
also easy to be interfered by lactic acid and leave fingerprints on the surface
of the product.
In
order to get rid of the defects of dispersivity and mismiscibility of Mg(OH)2,
it is necessary to develop and design good varieties with miscibility.
The
way to improve the grain size distribution and agglutination reaction
characteristics of crystals can be selected, and the way to implement surface
treatment of unsaturated high fatty acids, saturated fats and multi-component
with excellent thermal conductivity can also be chosen.
The
principle of the flame-retardant grade of magnesium hydroxide is given: when
magnesium hydroxide encounters heat (340-490 degrees), it generates the surface
heat energy of the adsorbent and has the flame-retardant grade effect.
At
the same time, a lot of water vapor is released to dilute the oxygen on the
surface of the fuel, and the active magnesium oxide formed by the
transformation sticks to the surface of the combustible material, which further
blocks the realization of ignition.