Author: Philippe Bichot
3 minutes read

EXPLORING THREE TYPES OF ANTI-STATIC AGENTS FOR CONDUCTIVE FLOORING

What is the most essential parameter for you when choosing a conductive filler? Is it the required loading, the price, its influence on color and smoothness of the floor surface, or the stability of anti-static properties over time?

 

Achieving the targeted uniform conductivity level in static dissipative floors is heavily dependent on choosing the right conductive filler. This article compares three different types of anti-static agents that are frequently used to impart permanent, stable conductive properties to epoxy and polyurethane self-levelling floors: chopped carbon fibers, graphene nanotubes and conductive mica, and identifies the so-called “price per property” for each ESD additive. Ammonium salts and other nonpermanent anti-static polymer additives are not taken into account in this review due to their limited effect and high dependence on humidity and time.

Parameter	Chopped carbon fiber	Conductive mica	Graphene nanotubes
Working dosage	1.5—4 wt. %	5—20 wt. %	0.01—0.04 wt. %
Resistance range (surface to ground)	1011—104Ω
Color opportunity	various	various	various
Required coat thickness	~2 mm	various	various
Can be used without conductive primer	none	yes	yes
Black dots on surface	possible	none	none
Stable resistivity over time	yes	yes	yes
Hot spots (resistance varies on surface)	possible	none	none
Resistance remains stable after abrasion defect on surface	none	yes	yes
Cost of performance	acceptable	high	acceptable

Strengths: ✅ Large variety of suppliers ✅ Good price per property

Weaknesses: ❌ Occurrence of insulative “hot spots” ❌ Problematic installation ❌ High cost of floors due to coating thickness ❌ Can’t be used without conductive primer

Carbon fiber is the most frequently applied anti-static agent for static dissipative flooring. Together, chopped and milled carbon fiber represent more than a half of the whole self-leveling anti-static flooring market share. They comprise 10–15 µm diameter carbon fibers based on coal tar pitch that are either chopped to a length of 2–6 mm or milled to a length of 0.13–2 mm. The working dosage for chopped carbon fiber is 1–2 wt.%, while for milled carbon fiber it is 1–6 wt.%. Both of these carbon fiber options have a good price per property ($0.2 – $1.5) because of the relatively low initial fiber price and concentration required.

However, because of the length of chopped carbon fiber (2 mm or longer), the thickness of the top/base layer must be at least as much. This limitation results in increased costs, as the top/base layer accounts for almost 60% of the total cost to the customer. Anti-static flooring with chopped carbon fiber has a better appearance than flooring containing milled carbon fiber, but is more sensitive to installation defects, and suffers from the occurrence of insulating “hot spots”.

Strengths: ✅ Can be used without conductive primer ✅ No black dots or insulative “hot spots” ✅ Variety of thickness of the coating

Weaknesses: ❌ High price per property ❌ High working dosage

Conductive pigments such as zinc oxide or mica are typically supplied in flakes or powder form. Conductive mica performs well when applied in anti-static flooring. It can be applied as a thinner ESD coat, allow various colours, have no negative influence on the mechanical properties and provide a high level of safety with an absence of “hot spots”. However these benefits come at a price, with conductive mica demanding the highest price per property. This severely limits the areas of use to niche applications which can accept the significant price increase.

Strengths: ✅ 100% ESD protection without “hot spots” ✅ Wide color range of flooring ✅ Reduced cost due to less raw material required ✅ Can be applied with standard equipment ✅ Can be used without conductive primer

Weaknesses: ❌ Need to follow dilution guideline

Graphene nanotubes (also known as single wall carbon nanotubes) are a relatively new product that is now being welcomed by the market. Their key advantage in comparison with traditional anti-static additives lies in the extremely low working dosage required to achieve the targeted level of conductivity – from as little as 0.01% of the total compound weight.

Thanks to their small diameter and high aspect ratio, this minimal dosage of graphene nanotubes is sufficient to create a uniform conductive network. Extra-low working dosages open the door to reducing the thickness of the ESD coating (as low as 25 microns DFT) and to a full color palette. Graphene nanotubes help to significantly reduce installation and maintenance time, yielding additional cost savings. Learn more about the performance of graphene nanotubes in ESD flooring

OCSiAl produces TUBALL graphene nanotube concentrates for anti-static epoxy and polyurethane flooring that make it easier to apply nanotubes in a standard manufacturing process. Request a sample of nanotube concentrate that suits your ESD flooring formulation:

Target system	Sovent-free epoxy			Solvent-based epoxy
Additive carrier	Plasticizer		Surfactant	Plasticizer & stabilizing agent
	Fatty acid glycidyl ester	Alkyl glycidyl ether	Ethoxylated alcohol	Fatty acid glycidyl ester, ammonium salt of polyolefins-based derivative	Alkyl glycidyl ether, ammonium salt of polyolefins based derivative
Product	More info	More info	More info	More info	More info