Signage special multi-purpose environmental protection screen printing water penetration ink

At present, the majority of signage screen printing inks are mainly based on oily solvents. They have high prices and serious pollution. They have potential fire hazards and seriously endanger the construction personnel. They must also use oily solvents when washing plates, causing a waste of funds. The water-based ink is based on water as the solvent, compared with the oil-based ink, the price is low, the pollution to the environment is reduced, there is no fire hazard, no harm to the human body, and the water-washable version is available, and the price is low. Through the unremitting efforts of technicians, multi-purpose environmental protection water-based inks that have been developed and put into the market are well received by users. The ink is prepared by adding water-based penetrant, water-soluble auxiliaries, edible preservatives and imported macromolecule water-soluble dyes. The food starch is used as a bonding agent and reacts under high temperature to form a thick Paste, and then at 80 °C often pressure filter 800 mesh stainless steel mesh. Its features are water-based, environmentally friendly, easy to operate, low cost, water-washable version, delicate ink, exquisite image formation, full color, long weathering period and versatility.

The ink is suitable for screen printing patterns such as aluminum oxidation signs, electrophoretic coating signs, paint signs, PVC, acrylic, plexiglass and other flat signs. The printed pattern has no bumps, feels smooth, and has good color transparency without any damage to the surface of the signage. The dyes carried in the ink penetrate into the oxide layer, paint film, and resin in the surface of the signage. The following briefly describes the use of water-based penetrating inks.

First, aluminum oxide plate screen printing water penetration ink

Aluminium and aluminum alloys in the specific electrolyte and process conditions, due to the application of an external current to form an oxide film on the aluminum surface is called aluminum anodization. Due to the type of electrolyte and the nature of the oxide layer, aluminum anode oxidation can be divided into sulfuric acid method, chromic acid method, oxalic acid method, mixed acid method, hard and porcelain oxidation method. Due to the simple composition of sulfuric acid oxidation, the bath is stable, easy to operate, and low in cost. At room temperature oxidation, a thick and colorless packaging machine can be obtained, which has a porous layer, strong adsorption, and easy printing. Therefore, the oxidation of aluminum signs using sulfuric acid oxidation. Aluminum oxide screen printing water penetration ink label process flow is as follows:

Mechanical polishing or sanding → Remove grease → Cold wash → Hot wash → Cold wash → Dry → Chemical polishing or electrolytic polishing → Cold wash → Hot water wash → Cold wash → Anodizing → Cleaning 2 times → Drying → Screen printing water-based penetrating ink → Baking closed → washing → drying → mechanical polishing → cutting → inspection storage.

Precautions:

1. Use water-based screen printing, select the appropriate mesh of polyester mesh according to the thickness of the pattern line;

2. Because the oxide layer is easily contaminated before it is closed, it is necessary to pay attention to environmental cleanliness during operation.

3 after printing into the oven above 100 °C bake 20min;

4. After the baking is completed, allow it to cool naturally, rinse with clean water, and dry it for mechanical polishing.

Second, electrophoretic coating signs screen printing water penetration ink

The electrophoretic coating process, also called electrodeposition coating, is based on the phenomenon of electrophoresis, that is, the charged colloid ions move toward the electrode with the opposite charge sign under the action of the DC electric field and lose the charge on the surface of the plate (workpiece). It is deposited on the plate (workpiece) in an insoluble state, and is washed and dried to form a paint film.

Electrophoretic coating is a complex process, mainly in the following four aspects:

1. Electrophoresis

Disperse in the water charged colloidal ions, in the direct current electric field under the action of the electrode opposite its charge electrophoresis is called electrophoretic phenomenon.

2. Electrolysis

In the electrolyte (such as electrophoretic paint), direct current is applied to the solution, and oxidation and reduction reactions are performed on the electrodes respectively. This phenomenon is called electrolysis.

Since the cathode and anode of the electrolytic reaction release hydrogen and oxygen, respectively, the coated workpiece is prone to air bubbles. Therefore, the electrophoretic paint must be mixed with pure water or distilled water, and avoid impurities such as acids, alkalis and metal salts brought into the paint. Paint contamination leads to excessive electrolysis.
3. Electrodeposition

As electrophoresis moves to the vicinity of the workpiece, the phenomenon that the charged colloidal ions release electrons on the surface of the electrode and precipitate in an insoluble state is called electrodeposition, which is the main process of electrophoretic coating.

4. Electroosmosis

Under the action of an electric field, the phenomenon that the solid phase is immobile and the liquid phase moves is called electroosmosis. In the electrophoretic coating construction, electroosmotic can make the water liquid in the paint film on the surface of the coated workpiece seepage, ensuring the density and firmness of the paint film. In order to ensure the quality of the electrophoresis plate, please pay attention to the following issues when purchasing the electrophoresis machine:

(1) Electrophoretic power distribution must be provided with a soft starter, paint liquid temperature control device, time control device, overload protection and work warning device.

(2) The design of the electrophoresis tank must have a defoaming device for the auxiliary tank and it can be continuously circulated and agitated without leaving a dead angle. The number of stirrings per hour and the pump head must be reasonably designed according to the size of the tank body. If the electrophoresis equipment is designed properly, the use time of the electrophoretic paint can be maintained for several years without replacement. Otherwise, the surface of the electrophoretic sign may be uneven, so that the paint liquid in the tank will be scrapped in a short time, resulting in unnecessary waste.

Electrophoretic coating screen printing water penetration of the ink process: aluminum polishing → cold washing → hot water → pure water → electrophoretic coating transparent paint → rinse → baking → screen printing pattern → baking → washing → cutting → inspection storage.

From the above workflow, it is not difficult to see that the electrophoresis signage is simpler than the oxidation signage process, and the reject rate is extremely low.

Third, the surface spray cover light paint signs and PVC, acrylic signs screen printing water penetration ink method

1. Surface spray paint sign

The surface of the metal sign is processed cleanly. After the paint is dried, the screen printing pattern is re-entried into the oven and baked at a temperature of 120° C. for a time of 15 to 20 minutes. After cooling, it can be washed.

2. PVC, acrylic signs

Clear the surface of PVC, acrylic grease, screen printing water penetration ink, re-entry oven baking, the temperature is 100 ~ 120 °C, time is 15 ~ 20min, after cooling can be washed.

Source: Screen Printing Industry Author: Zhao Shu Zhong Zhang Kunliang