Electrostatic charges are mostly generated by friction (triboelectric effect) or from induction. They are producing negative effects as: dust, bad handling, electric discharges, sparks.
Their elimination can be done either with electrostatic bars (without any lasting effect), either chemically (with lasting effect) by using migrating agents in the resin and on the surface (these additives are using surrounding humidity to decrease the surface resistivity of the treated material from 1016 to 1010/12 ohms, this is avoiding any charge accumulation (charge is disappearing at once before growing), either by adding in the resin conductive materials as carbon or metal (these treatments which are difficult to process, give the possibility to reach very low resistivity as 105/6 ohms independently of surrounding humidity).
We developed several additives (migrating):
INTERNAL ANTISTATIC PRODUCT, as:
| AS-15 N | antistatic treatment for LDPE |
| AS-50 | antistatic treatment for LDPE, LLDPE and PP |
| AS-11 VG | antistatic treatment for PP, plasticized PVC |
| AS-11 N | antistatic treatment for PP, plasticized PVC |
MSG-190 G | antistatic treatment for PP, plasticized PVC (for short term treating!) and SURFACE ANTISTATIC. |
These additives are approved for food packaging and give efficient antistatic treatment with fast action (a few minutes to a few hours after processing) lasting several years (without rubbing) depending dosering (even at low humidity rate as 20 % at 20°C).
IMPORTANT :
Like all migrating agents, these additives are producing secondary effects:
- | sometimes positive | : | slip effect, antifog, demolding effect. |
- | sometimes negative | : | decrease of the surface tension: printing or gluing more difficult to achieve (dyne level must be checked, Corona or Flame treatment can be needed), lubricating effect in the process, seal ability can also be modified. |
We have produced optimum quality and rules of use for our additives in the limit of knowledge today's technology. We keep in mind, in our advices, your work conditions as compatibility, printing, seal ability, organoleptic, etc.
We are organized to measure your samples for surface tension (dynes/cm) and electrostatic performances (measurement of half decay and Rs under controlled atmosphere).
Comparatives electrostatic measurements must be done at constant temperature and humidity, performances measurements must be done at 20°C and 50 % humidity. The weight of water in the air must be known (it will strongly influence the performance of your additive). Performance at lower humidity, must also be checked.
A) surface resistivity: with 2 electrodes, can be operated with smooth and flat materials.
B) half decay time: electrostatic charge produced with a generator or by friction (triboelectric effect) is induced in the material and immediately after (with an appropriate field meter) we measure the time spend by the material to lose half of its electrostatic charge (for flat and thin materials, you can use a laboratory charge analyser). All measurements are done at 50% humidity and 20°C.
Surface resistivity (RS) | 1/2 decay time | Antistatic treatment quality (dissipative) (example: anti-dust treatment) |
| | |
1010 Ω (Ohms) | < 1 second | very good |
1011 Ω | 1 second | good |
1011 Ω to 1012 Ω | 5 seconds | good (acceptable) |
1012 Ω | 10 seconds | acceptable (to be checked) |
1012 Ω to 1013 Ω | 10 to 100 seconds | bad |
