Definition of a fabric print
A process in which a dye or pigment of various colors is made into a color paste and applied to a fabric to be patterned, which is called a fabric print.
Two common printing methods
• Flat screen printing
The patterned screen is flat and tight on the frame, and the color paste is printed on the textile to form a pattern by the action of the printing blade.
The advantage of flat screen printing is that the size and color of the unit pattern are limited, and the color is rich, which is suitable for fabrics that are easy to deform. The shortcoming is that the straight pattern is easy to print, and the output of the shift is low.
• Round screen printing
The rotary screen printing machine is based on the automatic flat screen printing machine. The flat net is changed into a cylindrical metal nickel net. The color paste is pumped into the circular net and passes through the mesh at the pattern under the action of the scraper. It is printed on the fabric, and the output is high. The straight strip pattern is printed without joints, and the printed color is rich.
(3) Copper roller printing
It is a gravure printing. When printing, the color paste is embedded in the concave part of the flower plate. Under the extrusion, the color paste is transferred to the fabric to complete the printing. The pattern is clear and the output is high, but the number of printed sets and the width of the fabric are restricted.
Three-print post-processing equipment
• Steaming machine
After the printing process, the dye on the fabric is fixed on the fiber at a certain humidity and temperature to complete the process of the device.
(2) Drying equipment.
Some printing products do not need to be steamed, and are fixed by heating, such as paint printing, and a common guide roller type baking machine.
(3) Washing equipment
Washing and washing equipment for removing the slurry on the fabric and the unfixed dye
Printing paste
The printing paste is a polymer compound which acts as a thickening agent in the printing paste. It is often first swelled in water to make a thick colloidal solution (printed paste), and then added to the printing paste.
• The role of the original printing paste in the printing process
(1) As a thickener for printing paste, to ensure the contour finish of the pattern.
(2) The dye, chemicals and additives are evenly dispersed in the original paste according to the specified concentration.
(3) As a carrier for the diffusion of dye from the surface of the fabric to the inside, it acts as a carrier.
(4) Used as an adhesive, so that the printing paste at the pattern does not fall off the fabric during processing.
(5) as a moisture absorbent during steaming
(6) as a stabilizer and protective colloid for printing paste
• Performance of commonly used printing pastes
(1) starch
Commonly used in printing is wheat starch and corn starch. The color paste produced by the color paste has a high color yield, and the printed pattern is clear, but the printability and uniformity are poor. It is not easy to be washed after printing, and is often mixed with other pastes to improve printing. Performance.
(2) Etherified plant paste
Commonly used eucalyptus bean pods are made by etherification reaction. Commonly used such as synthetic tarragon, good printing performance, good pattern dyeing, high paste rate, easy washing, good acid resistance, water repellency Good, often used in chemical fiber printing and paint printing, and can be used in combination with other pastes.
(3) etherified cellulose derivatives
It is made from the cellulose fiber waste of the textile mill. Commonly used is carboxymethyl cellulose (CMC), the original paste is white, and can be used for reactive dye printing.
(4) Dextrin
It is an intermediate product degraded by starch. The white dextrin has high solid content and high water repellency after being paste. It can be used for chemical fiber fabrics, especially cationic dye printing, to obtain fine and clear patterns; yellow dextrin and printing dye penetration Excellent in properties, levelness and plasticity, high solid content, excellent dyeing resistance, often used for vat dye printing.
(5) Natural rubber
It is made from the liquid juice secreted by plants. It is commonly used in the production of long gum and gum arabic. Long gel has a high paste rate, good water retention, high color yield, easy washing, and is suitable for printing of soluble vat dyes and phthalocyanine dyes. It is often mixed with starch paste. Acacia gum is usually made into 50% original paste, which has high solid content, good water retention, high adhesion, easy washing, acid and alkali resistance, suitable for wool, silk and chemical fiber fabrics. printing.
(6) seaweed
The most commonly used is sodium alginate, which is derived from Sargassum and kelp. Its original paste has good chemical stability and compatibility, good printing performance, good leveling and easy washing. It is ideal for reactive dye printing. Paste, suitable for printing on chemical fiber fabrics and compact fabrics.
(7) synthetic paste
Paint printing is not suitable for the application of natural thickeners. It is often thickened with emulsified oil emulsified paste and thickened with synthetic thickener. When emulsified paste is used for paint printing, the color is bright and the pattern is smooth, but it causes volatile oil pollution of fire oil. Synthetic thickening The agent has very low solid content and good thickening effect. It is an ideal paste for flat net and rotary screen printing. It has clear flower-shaped lines and can be used for chemical fiber fabric printing.
Paint printing is a printing method in which a coating (coloring agent) is printed on a fabric with a polymer compound (adhesive), and a transparent film having a certain elasticity and wear resistance is formed by high temperature treatment to fix the coating on the fiber.
• Advantages of paint printing
(1) Simple to use, concise process, no need to wash after printing, reducing wastewater discharge.
(2) It can be applied to various fibers and various fabrics, especially for the blended fabric, which is uniform in coloration and does not produce flashing color.
(3) The chromatogram is wide, the color matching is easy, the flower profile is clear, and the stereoscopic effect is strong.
• Composition of paint printing paste
(1) coating
The coating is a coloring agent for paint printing, which is in the form of a slurry. It is prepared by adding an inorganic pigment or an organic pigment to an emulsifier, a wetting agent, etc. The coating is required to have good tinting strength and hiding power, excellent chemical stability, and particles. Be fine and even.
(2) adhesive
Most of the binders are polymer compounds obtained by copolymerization of two or more monomers. After post-treatment, a film with abrasion resistance, colorless transparency and strong adhesion can be formed on the fabric. Excellent chemistry is required. Stability, soft feel after film formation, smooth and elastic.
• Non-crosslinking adhesive
Refers to the absence of reactive groups in the structure of the polymer, and the addition of a crosslinking agent. Improve the anti-friction fastness of the film. For example: adhesive BH, adhesive 104
• Cross-linking adhesive
The binder polymer contains reactive groups that react with the crosslinker and the fiber to improve the fastness. For example: Akramin FWR
• Self-crosslinking adhesive
The binder molecule contains a group which can initiate a crosslinking reaction, and forms a strong film by self-crosslinking reaction under high temperature. For example: Dongfeng self-crosslinking adhesive RFN
(3) Crosslinking agent
Also known as fixing agent or bridging agent, its purpose is to improve the wet processing and rubbing fastness of the paint printing, reduce the baking temperature of the adhesive and shorten the baking time.
• Thermosetting resin
Commonly used trimethylol melamine ( TMM ) dimethylol dihydroxycycloethylene urine ( DMDHEU )
• Active polyfunctional compounds
Such as: Accra Ficks FH crosslinker 101
(4) thickener
Emulsified paste and synthetic thickener are pastes for color printing of paints. Emulsified paste is a white paste obtained by high-speed stirring of white oil and water with emulsifier. It has good printing performance and is baked after printing. The dry emulsified paste is volatilized; the synthetic thickener is a high molecular compound, which has the advantages of convenient slurry adjustment, low solid content, clear printing outline, no need for washing after printing, and can replace the emulsified paste.
(5) Catalyst
Catalyst is added to the paint printing paste to accelerate the crosslinking reaction rate of the binder and reduce the baking temperature after printing. The commonly used catalysts are ammonium sulfate and magnesium chloride.
(6) hygroscopic agent
It can keep the surface of the paste moisturized, without skinning, and improve the stability of the paste at high temperature. Urea is commonly used.
(7) Softener
It can make the surface of the fabric smooth, soft to the touch and improve the rubbing fastness. Common silicone softener.
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