What exactly is printing?

The process of printing dyes, pigments and coatings on the surface of cloth, leather or other objects through a flower tube or screen is called printing.

The principle of printing is similar to that of printing.

Fabric printing has a long history.

China used stencil printing during the Warring States Period (see History of Dyeing and Finishing in China).

India in BC

Woodblock printing has existed since the 4th century.

Continuous gravure cylinder printing began in the18th century (see cylinder printing).

Screen printing is developed from hollow board, which is suitable for small batch and multi-variety printing of deformable fabrics.

In 1960s, seamless metal rotary screen printing was applied, which provided conditions for continuous production and its efficiency was higher than that of flat screen printing.

In the late 1960s, transfer printing appeared. Using the sublimation characteristics of disperse dyes, the dyes on transfer paper can be transferred to polyester and other fiber fabrics by heating, and fine patterns can be printed.

In 1970s, a jet printing method controlled by computer program was also developed, in which various dyes were intermittently sprayed from many combination ports to form color patterns, which were mainly used for carpet printing.

Calico classification according to the process:

Commonly used are direct printing and indirect printing (resist printing, discharge printing and burnt-out printing).

Direct printing: dyes or pigments are directly printed on white or light-colored fabrics, and then the patterns are obtained through post-processing such as steaming. The process is short and widely used.

Indirect printing: you can't see the effect when printing, and the effect will be displayed after post-processing.

Anti-dye printing is a substance printed on fabric to prevent dyes from dyeing or developing color, and then dyeing or developing color, so as to obtain patterns on dyed fabric.

Anti-discharge printing is a printing process in which substances are printed on dyed fabrics to eliminate dyed dyes, and patterns are obtained on dyed fabrics in the post-treatment process.

Rotten flowers are usually made of polyester cotton. Dye the base cloth into the required color or white, and then print the protective material on the cloth. In the post-treatment, the unprotected cotton was corroded by a strong corrosive agent, and the rest showed a flower-like effect.

Divided by the equipment used; There are usually two kinds: manual printing and machine printing.

1) Manual printing: Generally, the dye paste is scraped on the cloth by hand with a silk screen plate, which can be printed on one page or on the bottom.

It is characterized by less investment, convenience and flexibility, and the color registration is not limited to increase or decrease at will, but the output and quality are not as good as those of machine printing.

2) machine printing: a, roller printing.

Carve a pattern on the flower tube, and print the dye on the cloth surface as required through the rolling of the flower tube.

Generally no more than 4 groups of colors.

B. screen printing.

(including flat screen printing and rotary screen printing) is to put the pattern on the screen, and then let the dye penetrate into the surface of the cloth through the mesh, which can increase the color registration.

With the development of modern science and technology, there are many other printing methods, such as transfer printing, bronzing, embossing, jet printing, flocking and so on, but they can't be counted as printing fundamentally.

It can also be divided into cotton printing, polyester-cotton printing, wool printing, silk printing, polyester printing, linen-cotton printing and so on.

Different raw materials are different in the finishing process of printing.

It can also be divided into different base fabrics: woven fabric printing; Knitted fabric printing.

The production process of digital printing is simply to input various digital patterns such as scanning, digital photos, images or computer processing into a computer, then process them through a computer color separation printing system, and then spray-print various special dyes (active, dispersed and acidic main paints) directly on various fabrics or other media through a spray-printing system by special RIP software. After processing, compared with the traditional printing and dyeing process, it has the following advantages to obtain various high-precision printed products on various textile fabrics.

Because the production process of digital printing gets rid of the processes of color separation, drawing, film making and screen making in the traditional printing production process, the production time is greatly shortened.

This model can be accepted by CD-ROM, e-mail and other advanced means. Generally, the proofing time does not exceed one working day, while the traditional proofing cycle is generally about one week.

In addition, due to the simplification of the process, the proofing cost is greatly reduced.

Shortening the proofing cycle and reducing the proofing cost will undoubtedly bring more market opportunities to enterprises under the market competition law that time is money and efficiency is life.

The principle of digital printing technology makes its products break the traditional production of color matching and flower length, and can make textile fabrics achieve high-grade printing effect.

Because digital printing technology can use digital patterns, the color of digital printing products can theoretically reach 654.38+06.7 million through computer color measurement, color matching and jet printing, which breaks through the color registration of traditional textile printing and dyeing patterns, especially in the printing of high-precision patterns such as color gradient and moire, digital printing has unparalleled advantages in technology.

In addition, the pattern of traditional printing is often influenced by the length of "flower back", while the concept of "flower back" can not exist in the process of digital printing, thus greatly expanding the space of textile pattern design and upgrading the product grade.

Digital printing production has truly realized the production process of small batch and quick response, and the production batch is not subject to any.

Because the digital printing production process is all computerized digital production, the production flexibility is greatly improved, and some products can even be delivered on the same day, which is desirable.

In addition, due to the application of computer technology, a series of patterns with the same pattern and different colors are printed, and designers constantly modify the patterns and colors during the production process, which has become a major technical advantage that distinguishes digital printing from traditional printing.

High-precision jet printing process makes the jet printing process water-free and colorless.

In the process of jet printing, the use of dyes is "distributed as needed" by the computer, so there is no waste of dyes and wastewater, and there is no noise in the process of jet printing controlled by the computer, so that there is no pollution in the process of jet printing, and the green production process is realized, so that the production of textile printing is free from the past high-energy production process, high pollution and high noise, and the production process of low energy consumption and low pollution is realized, which brings to textile printing and dyeing production.

There are several reasons for the defects in digital printing: poor plate joint (receiving printing) is the overlapping or mismatch (separation) of plate patterns.

Most of them are because the conveyor belt is not well adjusted or the table rules are not properly adjusted, which affects the accuracy of flower arrangement.

Pattern misplacement (misregister, misregister) is a printed matter with pattern misplacement.

Most of them happen when the flowers are not allowed, the carving is not good and the stickers are not good.

The printed part (printing frame, removal) of the plate frame mark presents the abnormal stripe mark in the shape of the plate frame.

Most of them are caused by bad conveyor belt and bad installation of pattern frame.

Bending (skew) means that the pattern is inclined or bent towards the warp and weft yarns of the fabric.

Usually, the printed grey cloth (silk) itself has weft skew, poor sewing, or the platen is skewed.

Part of the exposed warp or weft turns over or moves to the front and back of the fabric, and the pattern looks like a path left by a scratch.

This defect is mostly caused by poor penetration of color paste and improper post-printing treatment (uneven tension, etc.). ).

Uneven printing color (spots) A part of the printing has become a spot shaped like the skin of a sand fish.

This kind of defect mostly occurs when the viscosity of color paste is inappropriate, the screen is improperly selected or the paste is uneven.

The color of the bleed (melt) printing pattern oozes out, and the outline of the pattern is not clear, showing fuzzy color.

It is caused by low viscosity of color paste, extremely thick dye concentration, too much pulp absorption or too much moisture absorbent during printing.

A stain caused by the color of a printed pattern being contaminated to other parts.

Most of them happen when the printing platen is not cleaned, the drying after printing is not completely overlapped with each other, or the fabrics are in contact with each other in steaming projects.

Now, in some factories, thorough washing is carried out by adjusting the tension of the fabric under conditions similar to ropes.

The color difference (uneven scraping) of the two plates presents a certain color depth interval in the transverse direction of the fabric.

This defect often occurs when the screen frame and scraper are poorly installed or scraped unevenly.

Grade transfer printing first prints the pigment on paper to make transfer printing paper, and then transfers the color to the fabric through high temperature (heating and pressurizing the back of the paper). Generally used in chemical fiber fabrics, it is characterized by bright colors, delicate layers, vivid patterns and strong artistry, but this process is only suitable for a few fibers such as polyester.

The transfer printing process is simple, the investment is small, the production is flexible, and it is popular in the market ... But to be honest, compared with other printing types, the price of this transfer printing is a bit high, but there are certain grades of discharge printing (discharge printing), which uses dyes that are not resistant to discharge agents to dye the background color, and then prints with color dyes containing discharge agents or both.

Also known as line drawing or color painting.

Reducing printing This process uses the difference of chemical corrosion resistance of different fibers in interwoven or blended fabrics, and uses combustion agent to remove one fiber in the fabric through printing, leaving other fibers to form translucent patterns.

Also known as burnt-out printing or burnt-out printing.

Shrinkage printing is a method of printing, in which chemicals that can make the fibers expand or contract are applied locally. Through proper treatment, the fibers in the printed part and the non-printed part will have differences in expansion or contraction, so as to obtain products with regular concave-convex patterns on the surface.

For example, pure cotton printed seersucker is used as bulking agent.

Also known as relief printing.

The flat screen printing die is a polyester or nylon screen (pattern) with hollow patterns fixed on a square frame.

The color paste can penetrate the pattern on the pattern board, and the mesh is sealed with polymer film where there is no pattern.

When printing, press the pattern plate on the fabric, fill the color paste on the pattern plate, and scrape it back and forth with a scraper to make the color paste reach the surface of the fabric through the pattern.

Flat screen printing has low production efficiency, but wide adaptability and flexible application, which is suitable for small batch and multi-variety production.

Rotary screen printing die is a cylindrical nickel screen with hollow patterns, which is installed above the rubber guide belt in a certain order and can rotate synchronously with the guide belt.

When printing, the color paste is input into the screen and stored at the bottom of the screen. When the rotary screen rotates with the guide belt, the scraper closely attached to the screen scrapes against the flower screen, and the color paste reaches the fabric surface through the patterns on the screen.

Rotary screen printing is continuous and has high production efficiency. It has the advantages of roller and flat screen printing, but it still has some limitations in pattern fineness and printing color richness.

Remember: rotary screen printing has certain limitations in color selection.

Pigment printing is also called pigment printing. Because pigment is a water-insoluble coloring substance, it has no affinity for fibers, and its coloring depends on the coating of polymer compounds (adhesives) that can form films and the adhesion to fibers.

Pigment printing can be used for any fiber textiles, and it has more advantages in printing blended and interwoven fabrics. The process is simple, the color spectrum is wide, the flower outline is clear, but the handle is poor and the rubbing fastness is low.

Zinc plate printing is a printing method that engraves patterns on zinc plate, covers the fabric, and scrapes the patterns with color paste.

This method is suitable for printing large flower-shaped or thick fabrics, such as headscarves and towels.

Now sometimes chemical etching technology is used instead of hand-carved panels.

Drum printing is a process of printing on fabrics with copper drums engraved with concave patterns, also known as copper roller printing.

The cylinder engraved with flowers is called flower tube for short.

When printing, the color paste is first stained on the surface of the flower tube, and then the surface color paste of the non-engraved part of the flower tube is scraped off with a sharp flat scraper, so that the color paste is left in the concave pattern.

When the flower tube is printed on the fabric, the color paste is transferred to the fabric to print the pattern.

Each flower tube prints a color paste. If multiple flower tubes are installed on the printing equipment at the same time, color patterns can be printed continuously.

Counting printing is printing with counting technology.

With the continuous development of computer technology, digital printing technology is a high-tech product integrating mechanical and computer electronic information technology. It first appeared in the mid-1990s. The appearance and continuous improvement of this technology has brought brand-new ideas to textile printing and dyeing industry, and its advanced production principles and means have brought unprecedented development opportunities to textile printing and dyeing.

Jet printing is a printing method in which dye solution is sprayed on the fabric through the holes of patterned screen or the holes of patterned paper with a sprayer containing liquid.

Also known as jet printing.

In 1970s, a jet printing method controlled by computer program was developed. Various dyes were intermittently sprayed from many combination ports to form patterns of various colors, which were mainly used for carpet printing.

T-shirt screen printing is a common T-shirt printing method, which has simple manufacturing process and convenient printing, and is suitable for printing various printing materials on T-shirts.

Taking printing materials as examples, there are water slurry printing, mucilage printing, bronzing printing, flocking printing and so on.

Water-based printing paste is soluble in water, and the paste itself is relatively thin.

When printing, the printing paste evenly drains to the part to be printed through the mesh of the screen printing screen, so that the pattern is printed on the T-shirt.

Its characteristic is that only one color can be printed at a time. If you want to print a second color, you must wait until the last color is dry, so you don't need to steam it after printing. The advantage is that the printed fabric has good air permeability. As long as it is not printed on the spot in a large area, it feels basically soft. In the case that the resolution requirement is not too high, four-color dot printing can be done.

The disadvantage is that this printing paste is not suitable for printing on dark fabrics.

One point that needs special explanation: color fastness is related to the color depth of printed patterns. The lighter the color, the better the color fastness, and vice versa.

The basic process of mucilage printing is the same as that of water slurry printing, except that the material used is mucilage pigment, which will solidify on the fabric after drying, which is a bit like the feeling of sticking plaster on the skin.

Its characteristic is that only one color can be printed at a time. If you want to print a second color, you must wait until the last color is dry. Because the mucilage is opaque, it can print light patterns on dark fabrics, but it is not suitable for large-scale field printing because of its poor air permeability.

For patterns with scattered flowers or less rough lines, it can show its excellent performance. At present, the most common printed T-shirts on the market mostly use mucilage printing.

Foam printing T-shirt foam printing, also called three-dimensional printing, is developed on the basis of mucilage printing technology.

Its principle is that a certain amount of chemicals with high expansion coefficient are mixed in the mucilage printing paste, commonly known as foaming paste.

After the printing part is baked at low temperature, it is pressed and foamed at 130- 150℃.

Realize the three-dimensional effect similar to relief, and the foaming printing process can be high, medium and low foaming according to the specific requirements of customers.

The biggest advantage of foam printing technology is its strong three-dimensional sense, and the printed surface is prominent and swollen. This printing technology is widely used in all kinds of knitted fabrics.

Use of dyes and pastes

Before printing, the fabric must be pretreated to make it have good wettability.

The dyes used for printing are basically the same as those used for dyeing, and some smaller patterns can be painted (pigment).

In addition, there are special dyes for printing, such as fast pigments, fast amines and fast sulfonates.

Different dyes can be selected to print different patterns on the same fabric.

When printing, dye or pigment is mixed into the color paste.

After printing is dried, it is usually steamed, developed or fixed, and then soaped and washed to fully remove the paste, chemicals and floating color in the color paste.

Printing paste consists of dye (or pigment), hygroscopic agent, cosolvent and original paste.

The function of printing paste is to make the paste have certain viscosity and fluidity.

It is made of hydrophilic polymer paste, and commonly used pastes include starch, starch degradation products (white dextrin and yellow dextrin), starch ether derivatives, sodium alginate (or ammonium), hydroxyethyl Arabic gum, dragon gum, cellulose ether, polymer electrolyte, etc.

Pastes made of water, kerosene and chemicals are sometimes used as printing pastes.

Printing paste should have good stability to the chemicals in the color paste, do not react with dyes, have certain adhesion to fibers, and be easily washed off the fabric.

The viscosity of printing paste depends on the properties of the original paste.

When printing, it is difficult to print fine lines when the viscosity of color paste drops too much, and it is difficult for color paste to pass through the fine holes of screen when the viscosity is too high.

Steaming and its equipment

Steam is also called steaming.

The fabric printed with color paste is dried and steamed.

Steam condenses on the fabric, causing the temperature of the fabric to rise, the fiber and paste to swell, the dyes to dissolve and dye, and some dyes will react chemically during steaming.

Because of the existence of paste, the dyeing process of printing dyes is more complicated, and steaming time is longer than pad dyeing.

There are three kinds of steaming equipment: ① steaming box: hang the fabric on the bracket and push it into the box for steaming; (2) continuous steaming machine: the fabric is hung on the drum in a ring shape, and it moves slowly and continuously steamed; ③ Various rapid steaming machines.

Steam box and hanging continuous steam box are suitable for silk, knitted fabric and fiber fabric.

The steamer is steamed under closed conditions, but it cannot be produced continuously.

The steaming conditions vary with the properties of dyes and fibers.

When the vat dye printed fabric is steamed, the air in the steaming room should be excluded.

Disperse dye polyester printed fabric can be steamed in a closed steamer at about 65438 030℃, or steamed with superheated steam at about 65438 075℃ under normal pressure, or cured and fixed at about 200℃.

Connection shortcomings related to picture matching Digital printing machine, also known as general flatbed printing machine.

Universal flat-panel printer can print any material and irregular soft and hard objects, such as: metal, ceramics, crystal, glass, acrylic, stone, PVC, plastic, toys, U disk, cloth, wood, silica gel, leather and so on. Digital printers can reduce costs, reduce labor and improve efficiency for you, because digital printers do not need film plate making, one-time full-color imaging, accurate positioning and so on.

Digital printers completely replace traditional processes such as screen printing, pad printing and transfer printing, and are environmentally friendly products that can be exported, which is the trend of special printing of products in 2009.

Compared with digital printing, traditional printing has gradually moved away from people's realization. Let's take a look at the disadvantages of traditional printing.

Disadvantages of traditional special printing:

1, the screen printing cost of the film is high, and the printing cost is expensive;

2. Color correction is complicated, and once the version is finalized, it cannot be modified;

3, the process is complicated and the production cycle is long;

4. The cost of screen printing is high, and screen printing spots cannot be eliminated, so mass production is needed to reduce the cost;

5. Thermal sublimation ink is used for thermal transfer printing. First, print the picture on the transfer paper, and then transfer it to the surface of the medium. There are several problems: color deviation and positioning deviation. The finished drawing is also easy to scrape off and has poor firmness. Generally, protective film should be sprayed.

In addition, the transfer of special media also requires flexographic printing.

6. Traditional signs generally adopt the way of engraving+corrosion+colored paint filling, or laser engraving, which can only be monochrome signs and can't do anything about color patterns.

7. Repeated overprinter has high rejection rate and large color difference.

8. Skilled printing technicians with many years of rich experience are needed.

9, personnel need more, high proportion of manual.

The five most common printing processes are the process of printing patterns on textiles with dyes or pigments.

Printing can be divided into fabric printing, top printing and yarn printing, with fabric printing as the main one.

Top printing is used to make mixed color tweed; Yarn printing is used to weave fabrics with special color patterns.

Fabric printing has a long history.

China used stencil printing during the Warring States Period (see History of Dyeing and Finishing in China).

India had block printing in the 4th century BC.

Continuous gravure cylinder printing began in the18th century (see cylinder printing).

Screen printing is developed from hollow board, which is suitable for small batch and multi-variety printing of deformable fabrics.

Let's take a concrete look at several technical methods about reusable shopping bags.

Viscose foaming printing

Foaming material is added to the mucilage, and it is ironed at high temperature after printing, so that the protrusion of the printed part presents a three-dimensional effect. This year's latest foaming technology, in the process of plate making and color separation, can be layered and color separation foaming, highlighting the strong three-dimensional sense and feel.

Thermosetting ink printing

Thermosetting ink printing is mainly used to print exquisite animals, stars, animation games and other fashionable and chic high-definition pictures, as well as thick plates with right angles, rounded corners and special effects formed by different printing processes.

Thermosetting ink thick screen printing technology has become a popular trend in T-shirt clothing and handbag printing.

Thermosetting ink is a solvent-free ink, which can print fine lines, and has the advantages of flat surface, good fastness, dry printing, tasteless, high solid content, good scraping fluidity, manual printing and automatic machine printing, so we choose thermosetting ink for thick plate printing.

Thick printing ink has high hiding power, spot color, translucent, transparent and other types.

Advanced water slurry printing

Advanced water slurry printing is the most traditional printing process. Water slurry is transparent and can only be printed on light-colored fabrics such as white. Because of the single printing effect, it was once faced with elimination.

However, judging from the recent international popular printing trend, with the improvement of technology, water-based printing has become the first choice for fashion designers, and it is favored because of its super soft feel, strong permeability and rich expressive force.

Advanced environmentally friendly viscose printing

Environmental protection mucilage printing is characterized by strong color hiding power, which is suitable for printing fashionable printing patterns with clear lines, neat edges and accurate color matching. It is mostly used for printing high-end fashion and T-shirts, and it is also the most widely used fabric.

High-grade printed works with soft hand feeling, strong elasticity and good color fastness after printing need to be ironed and shaped at high temperature.

High elastic thermal transfer printing

Thermal transfer printing is a new printing technology, and there are more than a dozen different technologies in transfer printing itself. Commonly used offset printing, can print a photo-level delicate effect, suitable for printing photos and details with gradient colors.

However, the disadvantage is that the production batch requirements are large, and generally more than 2000 pieces can reach the economic cost.

Thermal transfer printing is suitable for cotton and non-woven fabrics, which can greatly improve the product grade of reusable shopping bags.