Positive Pattern PS Platemaking Process (7)

3. Develop black ink and glue
(one). In addition to developing black ink. Developing black ink is a kind of black ink made of oily substance and aqueous substance. It is an emulsified ink emulsified by oil phase and water phase substance. The developing black ink is applied to the printing plate surface. The oily substance is absorbed by the graphic part, and the aqueous material is absorbed by the blank part, which not only improves the lipophilicity of the graphic part, but also improves the stability of the blank part. Therefore, whether it is a baked plate or a plate that has only been developed and dirty but not baked, the developer black ink is applied. In addition, the application of the developed black ink makes it possible to darken the text and also to check the quality of the print.

The oil phase material in the black ink is composed of terpene resin, turpentine oil, carbon black, and oil-soluble emulsifier. The waterborne substance is composed of gum arabic (or carboxymethyl cellulose), water-soluble emulsifier and water, commonly used emulsifiers. There are Span-60 and Tween-60.

Terpene resin is a linker in developing black ink and is an unsaturated terpenoid. It can be dissolved in the mineral oil of turpentine oil, kerosene, gasoline, etc., and has excellent lipophilic properties. It is used to formulate black ink, has good affinity to the photosensitive layer, and has good ink receptivity. When used, terpene resins with higher boiling points are generally used because the low boiling terpene resins tend to volatilize when heated.

Turpentine is a good solvent for terpene resins and consists of cyclic hydrocarbons. It is volatile and flammable, and has a strong affinity for lipophilic substances.

Carbon black is a pigment in a black developing ink. It is an amorphous powder. It is insoluble in any solvent. Its dispersibility in the binder is also poor. Carbon black must be mixed into the terpene resin when preparing black ink. After grinding by the grinding roller of the grinding roller, it can be dispersed evenly.

Span-60, also known as emulsifier-S or emulsifier S-60, is a commercial name for sorbitan stearate, which is formed by the condensation of sorbitan and higher fatty acids and has the formula C24H46O6. Span-60 is a non-ionic surfactant, is a high quality water-in-oil (W/O) emulsifier, has good emulsifying, dispersing, and wetting properties and is soluble in water. It is used with Tween-60. Emulsification effect is more obvious.

Tween-60 is made by the condensation of Span-60 and ethylene oxide. Its molecular formula is C64H126O26. It is a high quality oil-in-water (O/W) emulsifier with good emulsifying, dispersing and wetting properties, and is soluble in water. Warm water, often used with Span-60.

Gum arabic is a hydrophilic colloid that is used in developing black inks. Its function is to enhance the hydrophilicity of the blank. Gum Arabic has a higher market price and can be replaced with hydrophilic colloidal CMC (powdered methyl cellulose).

There are many formulas for developing black ink, one of which is listed below for reference.

Black ink formulation:
Pre-olefin resin 100g,
Turpentine oil 200ml,
Carbon black 50g,
One 60 3 g
Tween 60 l4g,
Gum arabic 8 g,
Water 1000ml.

The steps for preparing the developed black ink are as follows:

(1) According to the proportion of the formula, the terpene resin is dissolved in the turpentine oil at a temperature of 50-60° C., carbon black is released, and the mixture is uniformly stirred; then the mixture is ground into a grinding machine until the carbon black particle size reaches 4 to 1. When the carbon black is uniformly dispersed in the terpene resin at 6 μm, the grinding is stopped and the resin black ink is formed.

(2) According to the proportion of the formula, Dissolve Span 60 into water at 60°C, and mix the resulting solution with resin black ink to form oil phase material.

(3) According to the proportion of the formula, Tween 60 and gum arabic are dissolved in water at 60°C, and then phosphoric acid is slowly added dropwise, the pH of the solution is adjusted to about 5.5, and the aqueous phase material is formulated.

(4) Slowly inject the aqueous phase material into the oil phase material while stirring. At the beginning, the added water phase material is less, forming a water-in-oil type emulsion; with the increase of the amount of water phase material added, the emulsion When the viscosity of the emulsion rises, when the amount of water phase material in the emulsion reaches a certain amount, the viscosity of the emulsion drops sharply, and the water-in-oil type is converted into an oil-in-water type, and the developed black ink with good performance is obtained.

The developed black ink is prepared by the above method, and the emulsification speed is fast, the particles are fine, the water phase and the oil phase are uniformly dispersed, and it is not easy to separate and separate; the performance of the developed black ink is good and stable.

The application of the developed black ink is relatively simple. For baked plates, a gum arabic solution was first applied to the surface of the plate to make the plate wet, and then black ink was developed. For unbaked plates, the developed black ink can be applied simply by using a squeegee to remove the developing water and washing the water remaining on the plate. Apply black ink gently with a slightly damp sponge

Wedding & Christmas Greeting Cards

Wedding Cards, Greeting Card, Birthday Greeting Card

Paper Boxes,Paper Cards Co., Ltd. , http://www.cnpaperbags.com

This entry was posted in on