Digital textile printing | process step by step | Advantages & disadvantages

Digital textile printing

Digital textile printing is described as any inkjet-based method of color printing on fabric. Most notably, it is characterized when it comes to printing small designs on clothing and printing large designs on a large format roll of textiles. The latter is a growing trend in visual communication, where advertising and corporate branding are printed in polyester media. Examples are flags, banners, signs, and retail graphics.

Simply put, when digital images are reproduced on a physical surface, it is called digital printing. The physical surface can be in the form of paper, cloth, plastic, film, etc. In digital textile printing, once the design is created, the fabric can be printed directly from the computer. No other steps are required for this process. Just as pictures can be printed on paper, designs can be printed on cloth.

Digital textile printing is considered 'next generation' printing which is quite different from conventional fabric printing. As fabric printing goes digital, many textile entrepreneurs are coming forward to invest in digital printing technology, as it is the most emerging method of printing. In India, the textile industry is adopting digital printing technology by printing fancy designs on sarees and garments to meet the demand of domestic and international markets.

The colors used for digital textile printing are different from the colors used in traditional printing. The most popular dyes for digital printing are acid dyes, reactive dyes, and dispersed dyes. These dyes can be used for all commercial applications, and have features such as bright colors, low to medium salt content, and high color fastness.

Acid ink is used for digital printing depending on the fabric, such as silk and nylon; disperse ink for polyester and reactive ink for cellulose-based fabrics such as cotton, linen, and rayon. Furthermore, these dyes are compatible with low-cost ink systems.

History of digital textile printing

Digital textile printing began in the late 1980s as a possible replacement for analog screen printing. With the development of a dye-sublimation printer in the early 1990s, it was possible to spread low-energy sublimation ink and high-energy disperse ink directly into textile media, in contrast to dye-sublimation ink printing on transfer paper, and in a separate process using a heat press, transfer it to the fabric. The concept of digital printing in textiles has been around for some time. Carpet inkjet printing machines have been used since the early 1970s. Digital inkjet printing of continuous rolls of textile fabrics was shown at ITMA in 1995. In 2003, ITMA introduced a number of industrial inkjet printers, which made digital printing a new industry standard in textiles. This new generation of machines had much higher output, higher resolution printing heads, and more sophisticated textile material handling systems that allowed a wide variety of fabrics to be printed.

Pretreatment for digital textile printing

The main reason for separating dye ink from thickeners and other chemicals and applying the fabric separately. All inks are less stable and have less storage stability, as reactive dyes are more likely to hydrolyze when the ink contains alkali. The chemicals in the ink cause corrosion of the jet nozzle; the harmful effects of sodium chloride on steel surfaces are well known, for example; the ink should have low electrical conductivity for use in ‘charged drop’ continuous printers. The presence of large amounts of salt in aqueous ink reduces the solubility of the pigment; Jet printing requires concentrated ink due to the small droplet size.

Cotton, viscose rayon, and lyocell fabrics are usually jet-printed with reactive dyes in a two-stage method, meaning the fabric is dense and pre-treated with alkali, while the ink contains dyes. A pre-treatment liqueur is usually applied with a padding mangle, although it can be screen printed.

i. Pre-treatment for reactive dyes (MCT type) on cotton, viscose rayon, and lyocell fabrics

a. 100 g/L Medium viscosity sodium alginate, e.g. 6% Lamitex M5

b. 100 g/L Urea

c. 20±30 g/L Sodium carbonate

d. Pad (approx.75% pick-up) ± Dry at120°C or below

e. For viscose rayon increase urea to 200 g/L and add10 g/L Lyoprint RG (Ciba)

f. The reason for the low drying temperature is that urea is unstable at high temperatures and this results in high levels of smoke when the stenter comes out.

ii. Pre-treatment for silk prior to reactive ink-jet printing

a. 10 g/L Lyoprint RG (Ciba)

b. 100 g/L Alginate medium viscosity, e.g. 6% Lamitex M5

c. 100 g/L Urea

d. 30 g/L Sodium bicarbonate

e. Pad (approx.75% pick-up) ± dry at low temperature, 100±120°C.

iii. Pre-treatment for wool and silk prior to acid dye ink-jet printing

a. 150 g/L Guar gum thickener, e.g. Meyprogum NP 8 (8% solution)

b. 100 g/L Urea

c. 50 g/L Ammonium tartrate solution (1 part water to 2 parts ammonium tartrate)

d. Pad (approx.75% pick-up) ± dry at low temperature, 100°C or below.

iv. Pre-treatment for polyester printed with dispersed dye ink

a. 10 g/L Cibatex AR (Ciba)

b. 100 g/L Sodium alginate medium viscosity, e.g. 6% Lamitex M5

c. Pad (70% pick-up) ± dry.

Digital textile printing machine

Digital Direct Inkjet Cotton Textile Fabric Sublimation Printer Inkjet Printing Machine-

A sublimation printer is suitable for inkjet advertising production and almost material transfer. It is widely used for eco-solvent printing and sublimation printing.

Eco-solvent printing: vinyl, flex banner, canvas, photo paper, PP paper, light film, car sticker, wallpaper, leather, gum, light cloth;

Sublimation printing: Printing pattern on sublimation paper, then transferring a pattern from sublimation paper to fabric by heat transfer machine.

MACHINE SPECIFICATIONS
Print Head	Brand	Eps	Japan
	Number	2 head or 2 heads
	Item No.	Eps XP600/DX5 head
	Print head Nozzle	8*180
	Resolution	1440DPI
Print Speed	Sketch Type	2 Pass	35 m2/h
	Production Type	4 Pass	25 m2/h
	Precision Type	6 Pass	15 m2/h
	Quality Type	8 Pass	10 m2/h
Operation Environment	Temperature	Degree	15-35
	Humidity	RH	40-70
Suits to	Eco-solvent printing	Vinyl, flex banner, canvas, photo paper, PP paper, light film, Car sticker, Wallpaper, leather, gum, light cloth
	Sublimation Printing	Printing pattern on sublimation paper; then transferring a pattern on fabric from sublimation paper by Heat transfer machine.
Ink	Ink Type	Eco-solvent printer, Sublimation printer
	Ink Color	CMYK	4 colors
	Ink Supply System	Negative Pressure Continuous Ink Supply System
	Ink Capacity	1000ml of each bottle
Parameter	Stoving method	Forepart and back two stages of heating
	Connector	Network line
	Medium dipose	Standard automatic feeding system
	Cleaning system	Automatic cleaning device/scraping ink device
Operation	RIP software	Maintop(free)
	Operation system	Windows XP/7, 32/64bit
Power	Power consume	800W
	Power supply	AC220V 50-60HZ
	Power Connector	Three-Socket
Package	Package size	281.5*84*77cm wooden case
	Gross Weight/Net Weight	220kg/190kg

Digital textile printing process step by step

You need to save your design in the correct print-ready format. It should be saved in CMYK format and it is 300dpi. This ensures quality preservation and keeps the digital printing process ready. If you do not save it at 300 dpi, the pixels will be scattered due to the low-resolution image and the final image may be affected. Your final design should ideally have a bleeding area in addition to a border.

If you are not going to do the designing yourself, but the printing company wants to help you with it, then you start with step 1 and continue. So let's take a look at the steps now:

Step i. Some digital printing companies have their own artists who create custom designs based on your needs and instructions. They may have a detailed discussion or meeting to fully understand your needs. Once the design is ready, mockups will be emailed to the customer; any changes you recommend will be included and the final version will be sent back to the customer. Once you move on we will move on to the next step.

Step ii. When the final design is approved, the artwork is preserved in the appropriate format with the correct resolution, as mentioned earlier, so that it is easy for the printer to recognize and print the product without error.

Step iii. First, the print heads are cleaned with a special liquid so that they do not dry out and are not damaged. This step is repeated after every 100 prints; Depending on the amount of color in the print, sometimes it is necessary to clean the head before 100 prints are completed.

Step iv. In this step, a series of checks are conducted. With each print, some waste ink is produced by the printer and it is collected in a drum. This drum needs to be monitored and should be emptied regularly so that no ink spreads. The printing machine has a container of cleaner; whenever the level of cleaner is low, it is filled. This cleaner is important for the printing process, and therefore care should be taken to ensure that the printer never runs out of this cleaner. Each time the printer stops and restarts, it uses a certain amount of cleaner and insufficient cleaner can damage the head. The ink temperature also needs to be checked; the printer must operate at temperatures between 20 and 25 degrees Celsius. Temperatures outside this range can damage the printer head.

Step v.  After all, checks have been successfully conducted the stage is set for the customer to print the artwork on the product of their choice. There are different-sized palettes for holding products. Depending on what is being printed, the appropriate size palette is attached to the machine and the product is spread on it ready for printing. The printed material or product is kept absolutely flat on the board without any creases. If there are any creases, the print will be distorted. The digital printer starts the actual printing and sprays the design on the material, side by side, to the print heads.

Step vi. Once the printing is complete the material or product is carefully removed from the palette. It is then delivered to the appropriate temperature through a large dryer so that the print is based on the item or sticks securely. The last step is quality testing. Once we are satisfied with the quality, the products are packaged and ready to ship.

Digital textile printing advantages

i. No color limitation, so highly detailed artwork, and better sharpness can be achieved.

ii. No screen is required during digital printing.

iii. Water consumption is 90% lower and electricity consumption is 30% lower than a traditional printing process. Because there is no need to wash the screen to apply new colors.

iv. Less manpower is required than conventional printing.

v. In digital printing, there is no need to calculate repetitive measurements. Any measurement design can be made.

vi. The design can be made with high resolution (300-1200 pixels/inch). So, the print quality is higher.

vii. There is no need for screen engraving and color splitting, i.e., this process is economical.

viii. Less waste of paint/ink and chemicals than flatbed or rotary screen printing.

ix. Low specific cost and low sample cost are the top advantages of digital textile printing.

x. Low capital investment.

Digital textile printing disadvantages

i. All types of fabrics can be printed except blended fabrics.

ii. Printing is not done on deep-color cloth.

iii. The higher the resolution, the more time it takes to develop the design.

iv. The cost of digital printing is much higher, but decreasing day by day.

v. Production rate is lower. It depends on the head of the machine. The higher the head of the machine, the higher the production. Typically, the production rate is 1-3 m / min.

vi. It is not possible to digitally print at any temperature. The temperature may be 25°C. We need to print digitally in the AC room, otherwise, the machine will shut down automatically if the temperature rises and the ink will freeze and the print head will be damaged.

vii. The head of the digital printer cannot be reused.

Conclusion

Digital printing is very popular in the textile sector, and it is growing in popularity as digital printing offers greater precision. Indeed, industry experts have predicted high demand for digitally printed fabrics. Digital printing offers you more diversity, faster change time, clarity, and lower overall cost.