The Wire and cable industry use various types of pigments to color polyolefins. Mainly they are employed for Wire Identification Methods. As in cables, it can be seen the coloring done on the outer layer is governed by a different set of requirements as from the inner layers. Pigments that are used in the wire and cable industries can be of two types inorganic and organic. Newer alternatives that are coming in to the market are known as the "mixed-phase metal oxide" pigments. Examples: yellow nickel Titanates and blue and green cobalt Aluminates. A relatively new entrant is the brilliant yellow bismuth vanadate. Organic pigments are also used but not as popular because they are more difficult to disperse than inorganic ones leading to possible loss in mechanical strength.
Some common examples are given in this table:
Used in Variety of resins
Red, yellow, brown, and black
Lead chromates and lead chromate molybdates
Colors can include bright yellow and orange
Comes in reds, yellows, oranges and maroons
Excellent for engineering resins
Shows good heat and light fastness, variety of uses
Comes in blue, pink and violet shades
Works in a wide gamut of resins
Factors in Selection of Pigments
There are various factors that govern the choice of colorants when it comes to the Wire and Cable industries:
Resistance to fading
Exposure (Outdoor & Indoor)
Wire Identification Methods In modern Wire and cable industry, there is a constant need for effective wire identification. Inkjet Marking- Inkjet technology has vastly improved over the years. With features of less maintenance and faster start-ups, Inkjet marking systems are now more reliable and user friendly. For the wire and cable industry, a dye or pigmented ink, with an Methyl Ethyl Ketone base is applied. Hot Stamp Marking- Hot stamp marking is still among the most inexpensive techniques for wire identification and is perhaps with exception of laser the only viable option for marking of the Teflon insulated wire. Four important factors here are correct air pressure, dwell time, wheel temperature, and lastly foil. Use of pigments come in the foil part. The foil comprises of a backing and pigment. The pigment gets transferred to wire insulation through the heat emanating from the character wheels. It is vital to note here that certain types of pigments can stick to only particular substrates and would need different temperatures to transfer them.