Inkjet printing and printing (2)

â—† The type of ink jet is divided into three types:

1. Oil-soluble type: It is not suitable for use in confined office space because of air pollution. The colorants used can be divided into two types: pigment type and dye type. Oil-soluble type is characterized by fast drying, so it is commonly used in the industry.

2. Water-soluble type: Most commonly used in the market. Can also be divided into pigment type and dye type, because the pigment is insoluble in water, it will precipitate, so the pigment particles must be made very small, to be less than 30μm, will have a better printing effect, otherwise use high resolution Can cause obstruction. The pigment's weather resistance, lightfastness, wash fastness, and fastness are all very good. The advantage of the dye is that there is no problem in solubility, and there are many types of colors, and the brightness is good, but the fastness is poor.

3. Hot-melt type: The above-mentioned Tektronix uses this type of ink, which uses a wax liquid that is liquid at 60°C, and immediately cools to a solid surface when it is sprayed onto the paper. Can also be divided into pigment type and dye type. Hot melt ink is less used.

â—†Physical properties and conditions of water-soluble ink

1. In order not to clog the inkjet head, it must pass through a 0.2 μm filter.

2. Clogging phenomenon does not occur. Ink crumbs can easily block the inkjet head.

3. Sodium chloride content should be less than 100 ppm, sodium chloride will cause the dye to settle down, and sodium chloride is corrosive. Especially in Bubble system, it is easy to corrode the nozzle. Although the nozzles are all made of titanium metal, It will still be corroded by sodium chloride at high temperatures.

4. Viscosity control (1~5 cp): Piezo system requires higher viscosity and Bubble system requires lower viscosity.

5. Surface tension (30~60 dyne/cm): Piezo system requires lower surface tension and higher surface tension of Bubble system.

6. The effect of the buffer solution: the pH of the ink is stable, and some dyes will precipitate due to the pH change.

7. The light fastness and water fastness are both high.

8. Shelf Life: The ink is manufactured from the factory to the consumer and used for the fastest three months, usually one year. Normally, the ink must be stored for 0.2 year.

9. Thermal stability: The thermal stability of the dye for the Bubble system is better because the Bubble system ink is heated to a high temperature of 400°C. If the dye does not withstand high temperatures, it will decompose or discolor.

10. The drying speed should be just right, and it is easy to plug the inkjet head or break ink too quickly. It is too slow to spread easily and makes the dot overlap severe.

â—†Dye for inkjet printing

1. The standard three primary colors are Cyan, Magenta, and Yellow, but the three primary colors cannot produce pure black. Therefore, the black color must be added, and the grayscale effect also needs black.

2. Ames Test Negative: Inkjet printing is usually in confined space and must be non-toxic.

3. Light fastness, washing fastness and water fastness: Inkjet printing requires the first two, ink jet printing must be required.

4. Heat resistance: Both ink jet printing and ink jet printing require heat resistance.

5. Solubility: Ink-jet printing requires less dye concentration, and ink-jet printing requires about five times as much dye density as inkjet printing.

6. Mob absorbance: Dye absorbance is high, a small amount of dye will produce a deep color, can solve the solubility problem. The light absorption coefficient preferably exceeds the absorbance of 2x104.

7. The stability of color: It is not sensitive to the change of material of printed material, so it is more convenient for consumers.