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Most of the driers are composed of metal and organic acid radicals and therefore belong to soaps. The general formula R-COOM can be used to indicate the properties of the driers and determine the metal portion, and the effect is related to the organic acid radicals.
The metal with driers performance can be roughly ranked as follows: (decrease)
Cobalt, manganese, lead, antimony, lead, iron, zinc, and calcium Among them, cobalt, manganese, and lead are the most important metals that can be used as the main driers, while others are used as the metal for driers.
The organic acid radicals are derived from organic acids and the organic acids used in the driers must meet the following conditions;
1 The formed metal has good solubility in oils and organic solvents.
The organic acid has a carbon chain segment and has a side chain, particularly a side chain attached to a carbon adjacent to a hydrogen group, and has good solubility and stability, such as naphthenic acid and 2-ethylhexanoic acid.
The greater the degree of unsaturation of the organic acid, the better the solubility of the metal soap, the solubility of the linolenic soap is good, and the solubility of the stearic acid soap is poor.
2 The solubility in water is small.
3 light color, small odor, less impurities.
4 The source is wide and the price is low.
The commonly used organic acids mainly include naphthenic acid, 2-ethylhexanoic acid, linolenic acid, pine oleic acid, and rosin acid. The properties of 2-ethylhexanoic acid are the most preferred, followed by naphthenic acid and flax After the oleic acid, rosin acid was the worst.
Naphthenic acid, also known as naphthenic acid, is obtained by separation, acidification and purification from petroleum. The n in the formula is 0-8, depending on the source, and the acid value is between 170-250. Naphthenic acid soap is currently the most widely used driers, has good solubility and storage stability, good drying effect, wide source, the only drawback is that some odors.
2-Ethylhexanoic acid, also known as isooctanoic acid, is obtained by oxidation of 2-ethylhexanoic acid with an acid value of 265-385. 2-Ethylhexanoic acid soap is a new type of driers with low viscosity and stable storage. Good quality, high drying effect, light color, small smell, but the current high price.
Linoleic acid is obtained by hydrolysis of linseed oil and distillation. It is a mixture of fatty acids such as linolenic acid, linoleic acid and oleic acid. The acid value is 190. Flax oleic acid has a low odor, but it is infrequently used due to its low degree of unsaturation, easy oxidation by air, darkening of color, reduced solubility, and reduced drying ability.
3, driers type and use
The performance of driers depends on the metal part, and the squeezing effect can be divided into two types: oxidative drying and polymerization drying. Therefore, there are two types of driers. One is based on oxidative drying, such as cobalt driers, manganese driers, etc. One is based on polymerization drying, such as lead driers, iron driers, and the like. It is most important to use cobalt, manganese, and lead as the main driers in both types. The characteristics of cobalt, manganese and lead driers are described below:
Cobalt driers
Is a dazzling driers, the strongest drying ability, characterized by fast drying of the surface, it is suitable for use with lead driers, so that the balance between the table and dry. The most common cobalt drier is cobalt naphthenate. It is a purple slurry containing 7.3% of cobalt; for ease of use, it is usually diluted with 200# gasoline into a solution containing 3% of cobalt, and its amount, in terms of metal cobalt, is usually 0.05-0.10% of the dry oil.
2 manganese driers
It is a polymeric driers, but it is not as fast as the cobalt driers promote the surface drying of the film, so it is conducive to the drying of the bottom layer. It has the disadvantages of deep color, yellowing tendency, and easy film brittleness. The common species is manganese naphthenate, a dark red solution containing 3% manganese. If manganese driers are used instead of cobalt, the amount should be more than that of cobalt. For example, when cobalt and manganese are used in combination, the amount of manganese is generally less than that of cobalt.
3 Lead driers
It is a polymeric driers, which can promote the drying of the oil film bottom layer to form a tough dry film with good adhesion. However, it has poor oxidative drying ability. If used alone, the surface will not dry for a long time. It is generally used with cobalt and manganese driers. . The common lead driers are also naphthenic soaps, diluted with 200-gasoline, containing 15% lead. The amount used, in terms of metal lead, is usually 0.5-1.0% of the dry oil.
The liquid dry oil is produced by precipitation, and the liquid cobalt dry oil is also called red dry oil. The production of slurry-like dry oil by the dispersion method, and the dry-like oil of the slurry-like cobalt, are commonly called white dry oil and are almost all produced by the ink industry. (To be continued)
Screen printing ink additives (medium)
2, the composition of driers