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Colorants
Colorants, pigments and dyes are dispersed in paints and caulks to
provide characteristics such as color, hiding power, bulk, durability,
and corrosion resistance. They are available in many forms and colorant
types. Common colors for colorants, pigments and dyes include black,
blue, bronze, brown, copper, gray, green, orange, purple, red, silver,
white, and yellow. Pearlescent and photoluminescent products are also
available. Important specifications for colorants, pigments and dyes
include pH and oil absorption, the amount of oil required to make paint
with a pigment. Typically, oil absorption depends upon the size of the
pigment particle, the type of binder, and the pigment’s physical and
chemical properties. Smaller pigment particles require greater amounts
of binder in order to cover larger surface areas and wet each of pigment
particle.
Colorants, pigments and dyes are available in several forms. Examples
include dry powders, granules, liquids, pastes, pellets, and chips. Dry
powders and granules are traditional forms that are available in the
widest variety of grades. Free-flowing pourable liquids and
high-viscosity pastes are master batches or concentrated dispersions of
organic or waterborne pigments that contain solvents or diluents. They
may also contain resins, additives or surfactants. Pellets and chips do
not contain solvents, but may contain additives or plasticizers. These
solid industrial pigments are easy to handle and feature a high
pigment-to-binder ratio. Depending on the pigment and resin type,
pigment levels of between 50% and 75% are achievable.
There are many colorant types for colorants, pigments and dyes. Examples
include barium metaborate, barium sulphate, chromium oxide, iron oxide,
lead carbonate, strontium chromate, zinc oxide, zinc phosphate, and zinc
sulfide. Titanium dioxide or anatase titanium is the white pigment in
most white paints and the primary hiding pigment in most other paints.
Carbon black, a pigment produced by the thermal decomposition of natural
hydrocarbons, is available in three types: furnace, channel, and lamp
black. Other colorant types for colorants, pigments and dyes include
organic and inorganic compounds, fluorescent and phosphorescent
materials, and the synthetic products of chemical reactions and
processes. Raw sienna, burnt sienna, raw umber, and burnt umber are
naturally occurring and commonly available.
Colorants, pigments and dyes are used in a variety of products and often
contain application-specific features. Common applications for
colorants, pigments and dyes include adhesives, art supplies, beverages,
ceramics, clothing, concrete, cosmetics, fibers, food, glass, inks,
paints, paper, plastics, polymers, soap and wax. Colorants, pigments and
dyes are also used in medical and biomedical applications such as tissue
staining. Specialized products are resistant to heat, weather conditions,
and ultraviolet light (UV). Some products are water soluble or can
conduct electricity. Others contain reinforcing fibers or are free from
heavy metals.
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- The guide to polymer processing technology,
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