Section 7 Textile Printing --1

Textile printing refers to a printing process in which various colors and patterns are printed on a textile using different printing methods.
The printing method can be classified according to the form of the textile or can be classified according to the process. According to the form of textiles, there are two types of sheet and finished products. Pieces are made into pieces and cut pieces. Finished products include clothing, towels, bags, etc.
According to the classification of printing process can be divided into direct printing, discharge printing, anti-inking printing, penetrating printing, grout printing, thermal transfer printing, blue printing cloth and electrostatic flocking method.

First, the characteristics of textile screen printing The meaning of textile printing and printing is very close, if you clearly distinguish the meaning of the two is very difficult. Broadly speaking, within the scope of printing, printing and dyeing can be referred to as a method of copying paintings using dip dyeing theory, and it is also a kind of printing.
According to the type of screen printing plate, the printing and dyeing methods are classified as follows:
Type 1 paper printing and dyeing method. This is a type of graphic that is carved on the paper in accordance with the design requirements. The graphic part must be carved and used as a printed film. This version is thicker than the screen printing plate.
2 screen printing and dyeing method. Screen printing and dyeing can be divided into: ordinary screen printing plate and roller screen printing two forms.
Screen printing and dyeing process is as follows:
Pattern Design → Making Screen Printing Plates → Modulating Colorants → Printing and Dyeing → Semi-finished Products Inspection →
Steaming → Washing → Fixing → Desizing → Finishing> 3 gravure printing. This printing and dyeing method is divided into two forms of engraving gravure and gravure.
According to the degree of mechanization, printing and dyeing methods are divided into manual screen printing and mechanical screen printing. Mechanical screen printing and dyeing mainly include manual printing and dynamic printing and dyeing.
Dynamic printing and dyeing is divided into:
a. walking automatic screen printing and dyeing; b. automatic screen printing and dyeing; c roller screen printing and dyeing; d. engraving gravure drum printing and dyeing.
According to the dyeing method, it can be divided into direct printing and dyeing.
The textile screen printing process is relatively complicated, the printing and drying equipments are simple and huge, the manual printing labor intensity is large, the heat treatment and drying requirements are relatively strict, and the manual printing speed is relatively slow, but the cost is low and the operation is easy. Roller type multi-color screen printing machine is fast, multi-color printing, high efficiency.

Second, a variety of textile fiber types of textile fibers, can be roughly divided into two major categories of natural fibers and synthetic fibers. Its specific classification is as follows:


Third, textile paste printing and dyeing ink used in textiles called printing paste. The principle of printing and dyeing is basically the same, but the dyeing liquid used for printing needs to be added with slurry to make thick and sticky color paste.
Slurry plays a role in transferring dyes during the printing process; it functions as a dispersion medium and a diluent when printing; it functions as a moisture absorbent and a thickening agent when steaming. There are many types of pastes with different properties, and they must be properly selected according to the properties of the dye used or the different printing processes.
(A) Types of color paste 1. Starch and its derivatives include wheat starch, corn starch, flour, dextrin and so on. Dry starch has strong hygroscopicity. The characteristics of the starch in the steaming of the fabric make the dye obtain a certain humidity and is easily absorbed by the fabric.
All of these pulps are food products. Starch and printing glues are mainly used to prepare colorants for ice dyes and vat dyes. As current reactive dyes and coatings are used in place of vat dyes, and alternatives are used, alternatives such as these have been used less frequently.
2. The plant gums are usually Long Jiao, Synthetic Long Jiao, seaweed, gum, white rattan and so on. Among them, dragon rubber is a natural product with few sources and high prices. In recent years, it has been replaced by synthetic dragon rubber. Seaweeds are most suitable for reactive dyes and are widely used; gums and white vines are not commonly used.
(1) Longjiao is obtained by solidifying the juice secreted from the skin of the shrub. It contains astragaloside, viscose, starch and some calcium, magnesium and potassium acid salts. It is a white or yellow translucent body. It is banded, flake or powdery. It is insoluble in water and must be used in water. Soaked in heat and boiled into a paste.
The use of dragon rubber as printing paste has the advantages of good penetrability, clear line appearance, uniform color and easy washing. It is often mixed with the same amount of starch, and the dosage is 6%-8%.
(2) Synthetic Longgel refers to the etherified plant slurry, which is formed by the etherification of cowpea plant seed gum. The basic composition of polysaccharide polymers, mannose and galactose. Both home and abroad use hydroxyethylated locust bean gum to synthesize Long Jiao. This paste has good permeability, uniform printing and easy washing. Due to the high viscosity of the starch paste, poor permeability, and hard-to-hand feel, it is often used in combination with synthetic dragon rubber, which also improves the lack of color ratio for synthetic glue.
Synthetic rubber has high paste-forming rate and large swelling property. It can be prepared with warm or cold water. It has a wider range of adaptability to acid and base values, good compatibility with dyes, and pure water-repellent or synthetic fiber fabrics with strong water repellency. Printability is also better. Because it is easy to gel with copper, chromium and aluminum salts, its metal complex dyes should not be used alone.
(3) The seaweed sodium slurry is a slurry extracted from plants growing in the sea (seaweed) and is rich in resources. It is one of the important pulps to replace the grain and is suitable for reactive dyes. Because the reactive dye is an anionic charge, it bonds to the hydroxyl group in the starch to reduce the amount of color. The sodium alginate slurry is also an anion-charged paste that is repelled by reactive dyes and does not cause dyes and slurries. Bonding affects the amount of color.
Sodium alginate is more sensitive to hard water, and it reduces alkali-based calcium alginate when it meets alkalinity. Therefore, sodium hexametaphosphate, a water softener, is added during the preparation.
When sodium alginate is used to modulate dye printing, it has the advantages of clear lines and good infiltration effects in addition to high color content. It is stable at pH 5.8-11, and is easily degraded during hot weather. It needs to add a small amount of preservatives.
3. The mineral slurry is mainly bentonite, composed of silicon, aluminum, iron and water. It has good hygroscopicity and the resulting paste is stable at temperatures not exceeding 80°C. Neutral or slightly alkaline solution, acid and alkali resistant.
In addition to warp and bleach sizing, it can also be used for starch modulation printing paste, such as the preparation of soluble vat dyes (in addition to soluble reducing green 1B) color paste.
4. Chemical Slurry (1) Emulsified Slurry uses two mutually incompatible substances to make a substance into a continuous phase, called "external phase", and another substance is a discontinuous phase. Called "internal phase." At present, there are many oil/water phases in China, that is, water becomes a continuous external phase, such as emulsified pulp A. The emulsified pulp has a certain viscosity, but it is not greasy. It is easy to scrape off from the surface of the cylinder, so that the flower-shaped outline is clear and the lines are smooth and clean.
Emulsified pulp can also be used in combination with dragon glue because it can act as a protective colloid. The emulsified pulp and agglomerate have a small amount of solid content, so when heated and baked, they will all vaporize. The surface of the fabric will hardly leave traces, and the hand feels better. The disadvantage is that because petroleum is used as a raw material, the fabric has a slight kerosene odor, but can be added. Hydrogen removal.
(2) Carboxymethyl cellulose is referred to as CMC slurry, which is obtained by etherification of cellulose with chlorotyroin. Due to the different number of cellulose hydroxyl groups that are substituted during the etherification reaction, the slurry properties are also different. The degree of etherification for printing and dyeing is 0.4-1.2, and its viscosity is about 1 Pa·s. The viscosity is stable at room temperature. When heated at 80° C. for a long time, the viscosity gradually decreases. It is suitable for the preparation of thermosetting, vinyl reactive dyes and dye bases such as chromophores and colorants.
(3) Methyl cellulose is another ether compound formed by the action of cellulose and dimethyl sulfate. Because its surface tension is lower than that of water, it is prone to bubbling, and it freezes silicates, phosphates, and carbonates. When aluminum, chromium, and tin alloys form insolubles, the paste prepared with it can replace some of the emulsification. Pulp, used for paint printing, can improve the stability and feel, can also be used for the preparation of vat dye printing and printing inks, soluble vat dyes, and is suitable for printing fine lines.
5. The animal slurry consists mainly of chitin, an organic colloidal nitrogen-containing polysaccharide material. Chitin is abundant in nature and is generally extracted from shrimp and crab shells. After removing acetic acid from 40% hot caustic liquor, viscous chitin is obtained. When the paint is printed, it is often used in adhesives, and it is also used as a binder for printing in dull white paints, but is easily yellowed after strong alkali heat treatment.
6. Preparation of raw paste In addition to emulsifying, all kinds of pastes must be prepared with water and various solvents before use to prepare the original paste, and then select the original paste and dye according to the nature of the dye and the requirements for pattern printing. Then adjust the color paste. Generally, the screen printing requirements are thick and difficult to flow (horizontal printers can be slightly thinner), while the roller printing machine is required to be thinner. The original paste formulation is shown in Table 4-21.
Table 4-21 Reference Formulation of Common Paste Formulation for Common Printing (Unit: kg)
Various dye pastes other than reactive dyes Aluminum sulfate antifouling paste
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