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n Hig h jet masstone is a requirement of hig h-end performance
coating applications such as automotive OEM or automotive
refinish. The demand for increased jetness has heightened with the
emerg ence of new resin technolog y. For this reason, raw material
and dispersion equipment suppliers have looked for ways to improve
their products. In this respect, Cabot Corporation is no exception
and continues to supply the market with innovative ideas for black
pigments that meet current market needs.
This technical paper presents a summary of information reg arding
友立资讯the effect certain fundamental properties of carbon black may have
on coatings performance.
It also outlines information on Cabot’s core line of hig h-color
carbon black pig ments, including the well-established MONARCH
1300 and MONARCH 1400 carbon blacks. Also covered are
two new pigments, MONARCH 1500 carbon black and the revolu-
tionary EMPEROR 2000 carbon black. While MONARCH 1300,
MONARCH 1400, and MONARCH 1500 carbon blacks are
oxidized pig ments, EMPEROR 2000 carbon black is based on
Cabot’s proprietary surface modification technology.
This brochure demonstrates the ability of EMPEROR 2000 carbon
black to impart superior jetness in high performance coating applica-
tions. The test criteria used to collect and to compare performance
data on these grades are highlighted in Section II of this brochure.
High-Color Carbon Blacks for High Performance Coating Applications
I. Carbon Black Properties and Coating Performance
One of the major reasons carbon black is used in coating applications is for its color properties. Colo
r development can be measured by conver-ting the color spectral reflectance data into three-dimensional color space, as provided by the Hunter Color formula measurements, as shown here.
In automotive topcoat applications, extreme black (low L* values) and deep blue undertones (low b* values) are the desired colors. The key properties of carbon black that can affect this color goal are:
1. Primary particle size/surface area
2. Primary aggregate shape/morphology
3. Surface chemistry
■ Effect of Primary Particle Size
Most pigments absorb and scatter portions of the visible light spectrum. The color of paint depends on how well the pigment is able to absorb and scatter light. Carbon black can be used to help increase the amount of light absorbed by a coating because it can absorb and scatter light more effectively than many other pigments.
As a carbon black’s primary particle size decreases, more surface area becomes available to incident light.
Also, primary aggregates tend to be smaller, assuming a constant structure level, resulting in a finer carbon black. The overall effect of the finer carbon black particle size is increased light absorption and more
efficient light scattering, giving a blacker or “jetter” color.
Hunter Color Definition
■ Effect of Structure
A carbon black characterized by aggregates composed of many pri-
mary particles with considerable branching or chaining is referred to as
a “high structure” black. Conversely, an aggregate having relatively few
particles forming a more compact unit is a “low structure” black.
As structure increases, the absorption and scattering efficiencies are
decreased. Thus, in primary particles of the same size, a high structure
典雅音乐花园black will exhibit lower jetness than a black having low structure.
■ Effect of Surface Chemistry
Increasing the volatiles content (that is, chemisorbed oxygen complex-
es) on the surface of carbon black will generally increase dispersibility
and lower viscosity in liquid systems. The dispersibility of carbon black
can also be enhanced through the adsorption of a limited amount of
moisture on its surface.
金属表面处理技术
To some extent, both the volatiles content and adsorbed moisture can function as surfactants, whereby the surface is more readily “wetted” by
the vehicle. However, as the volatiles content of carbon black increases,
its surface becomes more acidic. Thus, care should be taken when
formulating coatings systems.
■ Physical form
Most commercial high-color carbon blacks are available in either fluffy
or pellet form. The pellet form handles more easily (reduced dusting) and
normally costs less than the fluffy form. However, the process of densi-
fication, which is used to create the pellet form, tends to pack carbon
black agglomerates more closely, making dispersion more difficult than
with the fluffy form.
II. High-Color Carbon Blacks: Cabot MONARCH/ BLACK PEARLS 1300 & 1400, MONARCH 1500, and EMPEROR 2000 Carbon Blacks
■ Properties of an ideal high-color black for coatings
An ideal high-color carbon black should provide superior “jetness” in high-color enamels or lacquer coatings. As explained above, key properties of such a carbon black would include sufficiently fine-sized primary particles for increased light absorption and lower structure for increased light scat-tering.
The volatiles content and moisture level also can be adjusted to improve dispersibility. When these properties are obtained, superior “jetness” in high performance coating systems can be achieved.
■ MONARCH/BLACK PEARLS 1300 & 1400,
MONARCH 1500 and EMPEROR 2000 Carbon Blacks
MONARCH/BLACK PEARLS 1300 & 1400, MONARCH 1500 and EMPEROR 2000 are commercially available Cabot highcolor carbon blacks. Because of their properties, Cabot believes that they are able to impart superior “jetness” for high performance coating applications. They exhibit a very fine primary particle size (9-13 nanometers) for increased light absorption combined with a low structure (90-100 DBP) for increased light scattering. Together, these properties help to achieve superior color “jetness” and improved gloss in high performance coating systems. Additionally, the specifications for volatiles content and moisture levels of these Cabot carbon blacks are optimized to
help maintain dispersibility. MONARCH/BLACK PEARLS 1300 & 1400, MONARCH 1500 are Cabot oxidized high-color carbon blacks. These high-color carbon blacks are produced through the process of chemisorption of oxygen complexes onto the carbon black surface.
EMPEROR 2000 carbon black is Cabot’s newest pigment black and is produced using an innovative chemical modification technology. This patented technology allows specific functional groups to be grafted onto the surface of the carbon black particle. F or EMPEROR 2000, the function of the attached groups is twofold: first, it helps to anchor adsorbed surfactants and dispersants that otherwise can float free of the carbon black surface and affect coating performance, and secondly, it improves the ease of dispersion and dispersion stability of the carbon black yielding the desired coating jetness with a strong blue undertone. The new technology is illustrated here.
Conventional Commercial Carbon Black After-treatments
Cabot's New Surface Treatment (Chemical Modification)
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