Kewang's Multifunctional Liquid Photosensitive Ink and Artwork Copy (3)

Third, the use of attention 1. The surface of the substrate is cleaned and treated. The surface properties of the substrate are different. The methods of cleaning and surface treatment are also different. Some are easily oxidized, some are hydrophilic, and some are bright like mirrors. Ink is not easy to adhere to, and some are scared. Organic solvents erode, and some substrates are afraid of acids and alkali.

The surface of copper and copper is easy to be oxidized. Therefore, before printing photosensitive inks, the surface oil should be cleaned with a cleaning agent, and the surface oxides should be brushed off, rinsed again with tap water, and put in a person's anti-oxidation agent to soak for 5-10min/30-50. °C, the final hot air drying standby.

Stainless steel Stainless steel is used to remove surface oils with dilute aqueous alkali or detergent before printing, or dip with solvent, rinse with water and dry. For mirror stainless steel, the surface must be rubbed or sprayed with 20 # surface treatment agent (a syrup specially prepared by Kewang Company) before printing, and then dried at 100-120°C for 5-10 minutes. That is, a very thin transparent coating is formed on the surface of the stainless steel, especially for a screen with a high screen density, which can prevent the loss of dots, and can also improve the corrosion resistance.

Titanium plate Titanium plate cleaning is similar to stainless steel. If acid etching is used, a small amount of hydrochloric acid should first be added to the sodium fluoride to scrub the titanium layer; if electroetching is used, it can be directly etched.

There are many hydrophilic groups on the surface of glass and ceramic glass and ceramics. Before printing photosensitive inks, it is necessary to use a dilute aqueous alkali solution or detergent to remove surface oil stains. After drying, the surface must be treated with hydrophobic treatment, and the surface treatment agent should be used to wipe the glass or The ceramic surface is then dried at 100° C. for 10 minutes to chemically react a reactive hydrophilic group such as a hydroxyl group on the surface of the substrate with the active group in the surface treatment agent to become a hydrophobic surface, thereby increasing the adhesion of the photosensitive ink to the glass and the ceramic. Degree and resistance to development.

Aluminium Aluminium is an amphoteric metal that is afraid of acids and is afraid of alkalis. It cannot clean the surface with either acid or alkali. It can be dried by washing with a surfactant or organic solvent. If the surface is etched or electroetched with colored photosensitive inks, caustic soda cannot be used when removing the cured film of the ink. Because aluminum reacts with NaOH chemically and can only be soaked with polar organic solvents, its disadvantage is that the film is removed slowly. The higher cost is also detrimental to the health of operators. To this end, our company has introduced a five-color transparent liquid photosensitive resist oil. Its use and performance are the same as Type 800 photosensitive resist inks. After the aluminum foil is etched, the cured film is permanently retained on the aluminum foil and can be filled or electrophoretically filled without removing the film. The disadvantage is that the surface pinhole is not easily found. Can also use LPR-805 solvent developed photosensitive resist ink, solvent removal, no effect on the substrate, both acid and alkali double function, both for acidic etching, but also use alkali corrosion.

2. Coating of photosensitive inks Screen printing is usually used for flat substrates. The number of screen meshes depends on the process requirements.

When 820 photosensitive inks are used for chemical etching or etching, different substrates, different etching depths, and required photosensitive film thicknesses are also different. The deeper the etching, the thicker the film and the lower the screen mesh.

When using 820 spot color inks for coloring, the screen mesh number should not be too high, generally 100-200 mesh is preferred to ensure that the photosensitive film has a certain thickness and color concentration.

When using 820 four-color inks to make colorful metal paintings, glass or ceramic paintings, the number of screen meshes should not be too low, generally 350-420 meshes are preferred to ensure the sharpness of the sun, especially for high-line images. Use high-mesh screens (above 350 mesh) for full-page impressions.

The color order of 820 printing should usually be: black/cyan/magenta/yellow. Generally black is the first color, otherwise, the film is difficult to align. There is no absolute rule for printing color sequence, which can be determined according to the nature of the work.

When using 830 colored sand ink to make signs, the mesh is preferably 100-200 mesh. When it is larger than 200 mesh, there will be some sand particles that cannot be removed, which will affect the decorative effect. When the mesh is less than 100, the coating is too thick, the ink is wasted, and the film is not easily aligned. If the etching is deep, such as when the depth is more than 0.5mm, and the ink is desired to be in the same plane as the literal surface, the ink may be continuously scraped twice to increase the ink leakage. The 830 ink can also be diluted with cyclohexanone for spraying. The second color and the third color can be performed in the same manner.

For curved or extra-large materials, spray coating can be used. For flexible substrates such as aluminum foil, gravure printing can be used. Some manufacturers also gravure 820 photosensitive ink on the transfer film first. After the ink is dried, the heat is transferred to the curved metal product and then etched.

3. Pre-drying of photosensitive inks Printed products should be hot-air dried at 75-90°C for 30-50 minutes. If the temperature is too low or the time is too short, the solvent in the ink will not evaporate completely. When the film is exposed, there will be a sticky film phenomenon. After the development, the cured film will be dull. Conversely, if the temperature is too high or the time is too long, it may cause difficulty in development or no pattern at all. The product after drying can only be exposed after being cooled to room temperature. Otherwise, sticky film or misalignment may occur. In particular, multi-color superposition, often due to thermal expansion and contraction of the substrate, resulting in inaccurate positioning of the film, so that the picture is blurred.

4. Exposure light source LPR-820 can use high-pressure mercury lamp, iodine lamp, metal halogen and other light sources, in which the maximum luminous wavelength of the high-pressure mercury lamp is 365mm, which is consistent with the absorption wavelength of the ink, the highest efficiency, the shortest time, and the type of light source used, Lamp distance, power, ink coating thickness and other factors, such as 1kW high pressure mercury lamp, lamp distance 50cm, 200 mesh screen printing, photosensitive time is about 1min. Before the official production, the experimental version should be used to determine the exposure time so as not to waste. When covered with glass, the thickness should not exceed 3mm.

The darker the relationship between the exposure time and the color of the ink, the thicker the ink layer and the longer the required exposure time. The black is the longest photosensitive time, followed by blue, red and yellow. From the perspective of UV curing, the color sequence of 820 printing should be black/cyan/yellow/magenta, and the 820 photosensitive inks of different colors need different photosensitive time.

The sensitized time is directly related to the gloss of the ink cured film. The longer the exposure time, the more complete the curing of the photosensitive film and the higher the surface gloss of the developed film. Conversely, there will be reduced gloss or no light. For precision graphics, the optimum exposure time should be determined experimentally to avoid affecting the resolution.

Lifetime of UV lamps Most of the instructions in the instruction manual indicate that the UV lamp must be replaced after about 1000 hours of use. The aging factor of the lamp should also be taken into account when sensitized, and the exposure time should be appropriately extended.

If the reflector is not installed, about 80% of the UV light will not be able to irradiate the substrate due to scattering. Therefore, the UV curing device must be equipped with a safety lamp cover so that the UV light is concentrated on the substrate. The reflector must be kept clean. Dust or dust adheres to the reflector and affects the reflection. When not using a UV lamp, close the UV lamp cover to prevent dust.

5. The developing method is recommended to use the spray method, especially the fine lines or the high number of dots, it should be developed by spraying. The developer was a 1% aqueous sodium carbonate solution and no heating was required.

6. Drying The developed product should be dried at 80-120°C for more than 10 minutes as soon as possible, and then it can be glazing. If the photosensitive film is immersed in water for a long time, it will cause some of the dots to be lost or the cured film to fall off.

7. Covering In order to improve the wear resistance and scratch resistance of the product, increase the gloss, and extend the service life, the surface of the ink is often cured after development. To this end, we have developed UV-MI-20N solid metal varnish, high transparency, no yellowing after photocuring, 200-300 mesh screen printing, the surface of the cured film surface friction coefficient is very small, excellent wear resistance, high Hardness, high gloss, alcohol resistance, gasoline scrub resistance, but also has the ability to absorb sunlight UV.

8. Film design LPR-830 ​​photosensitive sand ink is suitable for making all kinds of precision metal signs, metal paintings, handicrafts, etc. The design should use the positive word with a larger background area to make the recessed part, ie, the color sand ink filling pattern larger. More prominent 830 ink decorative effect.

IV. Problems and Countermeasures Common Problems and Countermeasures

V. Ink technical indicators Solid content: 75%;
Viscosity (cps, 25°C): 4000-4500;
Thinner: Cyclohexanone.

Six, cured film characteristics Adhesion: 100%;
Pencil Hardness (H): 1-2H (before exposure), 2-3H (after exposure).

VII. Packaging It is divided into 1kg/barrel and 4kg/barrel.

VIII. Storage period is generally 6 months.

Nine, storage conditions should be stored in a cool, ventilated, dry place, is strictly prohibited from heat and light.




Source: Screen Printing He Ping