ROSINATED PIGMENTS

Rosinated pigments, 365 Rotanes, 365 Rubber, 366 Runaway reactions, 366 Rust, 367... 

With these lacquers, nitrocellulose-based primer-surfacers are used. As well as liquid plasticisers, a wide range of materials are used as plasticising resins short oil alkyds, maleinised oils, ester gum, rosin and bodied castor oils. Pigmentation is usually inert. Thermoplastic acrylics are often preferred under acrylic lacquers these are based on acrylic resins and cellulose acetate butyrate. 

Among the precipitants employed were tannic acid, tartar emetic, rosin soaps, fatty acid (stearic, oleic) soaps, sulphonated oils (Turkey red oil), earth lakes (mixed natural silicates), phosphates, casein and arsenious acid. The fastness properties of these pigments... 

Adsorption of e.g. rosin (abietic acid) at the pigment surface may - depending on the concentration of the rosin - reduce or accelerate the crystal growth. The presence of an excess amount of rosin during the production of diarylide yellow pigments of the Pigment Yellow 13 type affords an additional crystal modification, which can be identified by X-ray diffraction spectroscopy [4],... 

Studies of the metal-exchange process of P.R.49 (Na) to P.R.49 1 (Ba) [1] revealed that the process, apart from the temperature, is not only influenced by the crystal structure and the concentration of the barium ions but also by the amount of rosin soap. Colophony-based rosin which is assumed to act as a surfactant, is converted during the laking process into colorless insoluble rosinate salts. These salts are incorporated in the pigment til up to 30% by weight without a loss of tinctorial strength. Very often the color strength is even increased, accompanied by a color shift to more bluish reds. 

Diazotization of the aminosulfonic acid and subsequent coupling onto the sodium salt of 2-hydroxy-3-naphthoic acid initially affords the monoazo compound in the form of its soluble sodium salt. Subsequent reaction with chlorides or sulfates of alkaline earth metals or with a manganese salt, frequently in the presence of a dispersion agent, or rosin or its derivatives, at elevated temperature yields the insoluble BONA pigment lake. 

For instance in azo pigment manufacture, the crude product is given some form of surface treatment, such as with rosin, to control crystal growth, control aggregation and to aid in dispersion. 

By far the greatest market for this pigment, especially the rosinated grade, is in the printing ink market, where red lake C is known as a warm red, due to its distinct yellow shade. Within the plastics industry red lake C offers an economical azo red that finds use in LDPE and polyurethane where the end use allows such a pigment with relatively poor durability properties to be used as the system colorant. 

As the cylinder rotates in the press, the lower part of the cylinder is flooded with ink having a viscosity in the low centipoise range. The press ready ink may contain 7% pigment, 18% binder, such as modified rosins, nitrocellulose or a synthetic resin and 75% solvent. The solvents are usually blends of such materials as aliphatic hydrocarbons in the heptane range, toluene, acetates and alcohol. Water based systems are used in a number of applications. 

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