Research and application of light-colored conductive powder

Abstract: The charging of powder coating is mainly caused
by the accumulation of electrostatic charge caused by excessive surface resistance of the coating.

The static charge accumulation phenomenon generated by the application field brings great harm to the application of the coating, which is light and dusty, reducing the apparent performance and use value of the product, and seriously interfering with the accuracy and sensitivity
of the normal operation of the instrument and instrument due to electrostatic discharge.

It can even cause the combustion and explosion of certain combustible objects, and the consequences are unimaginable coatingol.
com
paint online.
The preparation of electrostatic conductive coatings has become urgent
.

1.
Preface

For a long time, polymers have been widely used
as insulators in the electrical and electronic industries.
However, after the polymer is incorporated with conductive micronish, it can become conductive, which is not an inherent property of the polymer itself, and its conductivity is achieved by conductive particles
.

It is used in hospital operating rooms, production assembly and transportation sites, large archive rooms, computer rooms, etc
.
Due to some subjective and objective factors, some static electricity will be generated, and a large amount of static electricity will accumulate, which will cause accidents, such as fire
.

The coating surface of these products must not only have aesthetic protection function, but also have special conductive and electric discharge function
.

There are two main methods of conductivity of powder coatings: blended type and intrinsic type, blended type is the resin itself is not conductive, in which the incorporation of conductive fillers to form conductivity, its conductivity relies on the incorporation of conductive particles to achieve, conductive particles provide free electron carriers, thereby conducting electricity, so it is called blended type
.

The intrinsic type is that the binder itself has certain conductivity, but the application has great defects, mainly the synthesis of conductive polymers, there are still many difficulties in construction, the technology is very complicated, the cost is high, so the current application is limited, this article mainly discusses the blended conductive powder coating
.

The principle of adhesion, in the coating is incorporated with conductive powder, it includes metal powder, non-metallic powder and metal oxide
.
Metal powders are: gold, silver, platinum, nickel, zinc and aluminum
.

Non-metallic powders include: graphite, crystalline and amorphous carbon black, acetylene black, etc
.
There are also some metal oxides such as zinc oxide, antimony oxide, etc
.
Conductive powders can be used in a variety of industries
.

At present, the application of conductive powder in powder coating has been relatively mature, and the application of general circumference is also relatively extensive, and the general milling manufacturer's dark or pure black powder can basically achieve a resistance value of 104, 109Ω, such a resistance value
.

The application value can fully meet the needs of customers, dark or pure black conductive powder is mainly a blended system, and the conductive main medium is conductive carbon black
.

Generally, the amount of addition is more than 2%, conductive carbon black is black low-resistance carbon black, generally can only do some dark products, can not be applied to light products, or white products, can do light conductive powder The current market is relatively small, to get light or white system conductive powder is currently more difficult, the application is not much
.

Applied to conductive materials is also rare phosphorus angle, can produce conductive powder enterprises are not many, the market conductive barium sulfate, conductive titanium dioxide, although there is a certain degree of conductivity, but generally can only do within 107Ω, and the price is not cheap, difficult to be accepted by the market, this article is not discussed
.

2.
Experimental part

2.
1 Main raw materials

polyester resin; Epoxy resin; TGIC； Stuffing; titanium dioxide; Powder additives (leveling agents, brighteners, benzoin, matting agents, etc.
)

2.
2 Experimental instruments

twin screw extruder; ACM mill; electrostatic spray guns; Oven; A4 drawing size 0.
5mm tinplate plate, heavy hammer surface tester, etc
.

2.
3 Preparation of powder test samples

According to the formula design (Table 1, 2), weigh different polyester resins, TGIC, epoxy resins, curing agents, other additives, conductive additives, mica powder, etc.
, through the extrusion of the extruder, crushing and grinding, and then sprayed on the tinplate plate
.

Data measurements were carried out, and the average value was taken 3 times using a heavy hammer surface tester (52.
4%RH 20.
4°C at a certain humidity temperature).

The determination of resistance value is in accordance with GB/T 16906·1997
.

3.
Results and discussion

As can be seen from the data in Table 1 and Table 2, the size of conductive resistance mainly depends on the amount of conductive additives used and their conductivity, and the use of other materials in the formulation will indirectly affect the conductivity
.

Most of the additives used in light-colored systems for conductive powders are wet muscovite as the matrix, using nanotechnology, through surface treatment and semiconductor doping treatment, so that a conductive oxide layer is formed on the surface of the matrix, so as to prepare a new type of electronic conductive functional semiconductor pigment (filler).

The formed conductive mica powder is scaly, and its appearance is generally gray-white or light gray powder, which has the characteristics
of light color, easy dispersion, small specific gravity, heat resistance, high chemical stability, corrosion resistance, flame retardant, good wave transmission, good conductivity and low price.

It can be used with color pigments to improve gloss without affecting its color, and can be used with other pigments to make a variety of light-colored, colored, near-white permanent conductive and anti-static coatings
.

Used in coatings to increase the elasticity of the paint film, its horizontal arrangement in the coating can block ultraviolet radiation and protect the paint film, prevent cracking, prevent moisture penetration
.

It can improve the mechanical strength, chalking resistance, temperature resistance, fire resistance, waterproofness, impact resistance and durability of the paint film
.
It is especially suitable
for use in anti-static oil tanks.

The data can also be analyzed that different systems, different patterns, different fillers, additives, etc.
have great changes
in the conductive data.

Why there is a difference, the author believes that it is not difficult to understand the difference in the difference in the system, because the resistance value of different binder resin is different, the resistance value of epoxy resin is the highest in the powder system, so the insulating powder is preferred epoxy system, so the conductive powder should not choose epoxy system
.

The same orange pattern powder, different orange pattern agent addition, will produce different pattern effects, different pattern effect production, its surface unevenness and the measurement tool contact point surface how much difference to produce data difference
.

The contact surface with strong three-dimensional sense of pattern will be significantly smaller than the data of three-dimensional sense flat, and the addition of some additives can improve some properties of the powder, but it will cause obstacles
in the conductive powder.

Generally, additives are small molecule substances, which will drift to the surface of the coating after film curing, hindering its conductivity, so it affects the conductivity value, and the conductivity of the filler will also affect the difference in resistance, and the mica powder resistance value in the filler is the lowest
.

Under the same system, the measured resistance value is: the plane powder is smaller than the sand grain powder, and the sand grain powder is smaller than the orange grain powder
.

Conductive additives can also be applied to the addition of powder, the effect is better than the internal addition of the same year, but because of its poor compatibility with the powder, it will produce fog shadow, loss of light and other phenomena, so the flat light highlight should be used with caution, and can be used for texture powders
such as sand grain and orange grain.

4.
Conclusion

In summary, in addition to the above factors, conductive powder also has to consider external factors of the production process, such as the number of revolutions extruded, temperature, etc.
, and each link needs to be more detailed
.

There is a link that is not paid attention to, may not be able to meet the demand resistance of the product, each product to get the best conductive effect, designers should consider a variety of aspects to achieve the ultimate product
.