Ink Materials and Composition Analysis (3)

Three packing

1) The role of filler in ink

The filler is a white powder that can be uniformly dispersed in the binder. The amount of ink used in the ink is adjusted according to the amount of ink pigment and the ink requirement. The role in the ink is roughly as follows:

a: Reduce ink costs

b: Adjust the ink ink

c: Adjust the color density of the ink

2) Types and Characteristics of Common Fillers

a: Aluminum hydroxide used in aluminum hydroxide inks is prepared by precipitation method, which is a commonly used filler in oil type inks. It is blended with a suitable viscosity varnish (dry linseed oil is polymerized at a certain temperature) to make Visley oil commonly used in printing. The amount of aluminum hydroxide in the ink should not be too much, otherwise it will inhibit the drying of the ink, and it will also reduce the gloss of the ink.

b: Barium sulphate used in barium sulfate ink is also prepared by precipitation method. The ratio is significant, the transparency is poor, and the amount of oil absorption is large. The use of ink alone will make the ink less fluid, and the amount of ink cannot be very high. Otherwise, ink pile-up will occur during printing. It can be used with pigments that are small in specific gravity, fine in grain, and require less ink after grinding to improve the fluidity of the ink.

c: Alumina White This filler is a precipitate of barium sulfate and aluminum hydroxide. The gloss is good, and the printing performance after the ink is made is also good, but if used improperly, the ink will be gelated or thickened. When selected, it can be ground together with varnish to achieve good flow and gloss.

d: The calcium carbonate used in the calcium carbonate ink is obtained by precipitation of calcium hydroxide and sodium carbonate. The calcium carbonate obtained by this method has good transparency and gloss. And calcium carbonate particles can be very small (0.02-0.1μm), can reach the scope of colloidal particles, it is sometimes referred to as colloidal calcium carbonate. Colloidal calcium carbonate is formulated in a certain proportion in the ink, which can improve ink flowability, glossiness, transparency, etc., and generally does not cause poor printing failure. In offset printing inks, resin-based offset printing inks are particularly used, and colloidal calcium carbonate is often selected as a filler to replace other types of fillers.

Four auxiliary agents

Auxiliaries are additives added to the ink to improve certain special properties or requirements of the ink, and can be additives for pigments, binders, and finished ink products. The purpose is to change the wettability of the pigment, the binder, the compatibility, and the performance of the ink itself or some special requirements. The content of adjuvants in the ink is very small, generally not exceeding 10%. The usual adjuvants in the ink are as follows:

1) Desiccant mainly refers to substances that promote polymerization drying of dry oil type vehicles. Most are cobalt, manganese salts or soaps.

2) Remover This auxiliary agent can effectively reduce the viscosity without substantially changing the body of the ink. Commonly used are waxes and gels (gum oils). In addition to the detackifying effect of the wax detackifier, there is also the effect of making the ink resistant to rubbing and increasing the slip; while the colloidal oil has the effect of de-sticking and maintaining the consistency and the body bone.

3) Thickeners are used to increase the viscosity of inks and binders, to improve the thixotropy of inks, to prevent the deposition of pigments, and to increase luster and dot reproducibility.

4) The anti-fouling agent is used to prevent the printed products from getting dirty. Generally, the starch is dispersed in the varnish and then incorporated into the ink.