Corduroy is a textile that people love, it was mainly used for spring and autumn clothing fabrics. In recent years, through continuous research and development, the use of corduroy has been expanded to wear, hang, pad, cover, lean, cover, and other aspects, and become a new force for decorative cloth. China is a major producer of corduroy, with an annual output of 400 million meters and nearly a thousand varieties. Regardless of output, quality or color variety, China's corduroy production is the leader of other countries in the same industry, and the products have many exports. The quality is “clear velvet, full fluff, soft touch, moisture absorption, washable, wear-resistant and color. "High fastness" and other features are well known at home and abroad. There are a wide variety of corduroy printing methods (such as frosted printing, burnt-out printing, three-dimensional printing, overprint printing, gold and silver powder printing, pearl printing, spray printing, etc.), each with its own characteristics, and its operating technology depends on different printing methods and printing. Material formulations, corduroy product structure, printing machinery, etc. There are major differences, the following, it will introduce the technical characteristics of the corduroy frost flower printing and the operation should pay attention to issues, to attract bricks and jade.
First, the characteristics and process technology of frosted printing
Frosted corduroy is a kind of technology and high value-added corduroy products because of its unique style and loved by consumers. Frosted corduroy is the use of strong oxidants (usually potassium permanganate or sodium hypochlorite) to destroy colored suede dyes and reactive dyes on dyed corduroy. The surface of corduroy is evenly decolorized with strong oxidants to make its surface. With the unique effects of cream and full fluff, soft touch, bright and lively color, good dimensional stability, frosted printed corduroy can be divided into a variety of styles, such as monochrome, two-color imitation color pull. Among them, the production principle of cream color bicolor pulling corduroy is to chemically and physically act on the surface of the fabric to make local frost white or frost white. It can also be dyed or printed to make it partially discolored and form velvet. Velvet bottom two colors and various flower patterns. Actually, corduroy cream printing also belongs to a discharge printing (ie, corduroy pull-out printing). Discharge printing, also known as engraving, has been used since the early 18th century and is still a major printing method. Discharge printing is to print a discharge agent (activator) in the graphic area. The discharge agent is used to remove the dye from the fabric, so that the graphics area is left with a neutral tone for printing graphics. It is the use of reducing agent and oxidant to destroy the color of the colored fabric (that is, the dye is printed on the colored fabric to destroy the pigment that has been dyed), and the printing method for obtaining the partial achromatic or colored patterns and patterns is achieved. The former is called white and the latter is colored. Because the pull-out printing and the pull-out printing can be applied to one pattern at the same time, they are collectively called discharge printing. The discharge printing process can be roughly divided into two steps, namely, dyeing the fabric into a single color and then printing the pattern on the fabric. In pattern printing, the printing paste contains chemicals (such as strong bleaching agents, also known as discharge agents) that can damage the ground color dye, and the base color is destroyed during the post-steaming process, so it can be produced by this method. Blue white dot pattern of the cloth, this process is called pull white printing. When a bleaching agent is mixed with a dye that does not react with it in the same colorant (reduced dye belongs to this type), color printing can be performed. That is, when the whitening color is destroyed, a stable dye for the discharge agent is added to the anti-pollution paste. When the dye is dyed at the drawn pattern, a colored pattern different from the ground color can be obtained. effect. Therefore, when a suitable yellow dye (such as a vat dye) is mixed with a colored bleach, a blue dot pattern can be printed on the blue base fabric. The background color of the discharge printing is mostly the floor printing that is dyed and dyed first, and its color is deep and abundant. This is the main purpose of using discharge printing. Discharge printing fabric can be printed by roller printing and screen printing, but it cannot be printed by thermal transfer printing. Because of the high production costs of the unpainted fabric compared to direct printing, the reductant required for use must also be carefully and accurately controlled. Fabrics printed in this way have better sales and higher prices. Sometimes, the reducing agent used in this process can cause the fabric at the printed pattern to be damaged or destroyed. The discharge agent is the main solvent used in the discharge printing. The discharge agent is a chemical reducing agent and has the effect of bleaching the dyed bottom. For different fabrics, the choice of the discharge agent is also different. For example, rayon fabrics and reactive dyes are generally made of carved white block or Degulin as discharge agents, and silk fabrics are usually selected from stannous chloride, while polyester fabrics are selected from Decolin as discharge agents. In addition, the whiteness requirement is not high, only for the shallow pull can also be used sodium hypochlorite as a discharge agent for printing, and acid dyes and disperse dyes, cationic dyes can be used as a discharge agent stannous chloride, sulfide and indigo dye available high manganese Potassium or sodium hypochlorite and other oxidants are used as discharge agents, but there is a need for selection of dyestuffs. Generally, those azo dyes that are easy to pull off are used as the background color.
Most corduroy fabrics are dyed with sulfur dyes, with less color pulling and more whitening. Commonly used oxidants are potassium permanganate and sodium hypochlorite as cream agents; indigo blue denim is generally used in these two oxidants. In addition, suitable thickeners (such as thickener CMS) should be selected for the discharge agent. Common usage formulas are: (1) thickener CMS (10%), add water (50%), stir well, then , Slowly add sodium hypochlorite (40%) while stirring; (2) Thickener CMS (10%), add water (40%), stir well; In addition, take appropriate amount of potassium permanganate, use warm water (50%) After dissolving, it is cooled, and then the cooled potassium permanganate aqueous solution is slowly added to the thickener solution while stirring. Pay attention to the compatibility of the discharge agent and the dye. For example, when using Acid Red C, this dye is not resistant to stannous chloride, so it produces an achromatic effect. While Chai Linyan 6B is resistant to stannous chloride, the adhesive is usually an acrylate.
After determining the discharge agent, it is necessary to select the appropriate paste to meet the printing requirements. The paste must have good water repellency and strong reductant resistance. At the same time, no reaction with the reducing agent is required. Only in this way can the sharpness and fullness of the printed product be ensured. The main components of DP-1 and DP-2 are polyurethane and acrylate copolymers, which have good water-holding properties, do not become dilute by adding whitening agent, and have excellent effect of pulling white ink, and are easy to use. It can be used for pulling white and also for drawing. It is suitable for flat screen printing on circular screens. It can also be used for manual desk printing. After printing, it can be processed by various methods such as steaming, pressing, high temperature and baking. Discharge effect. If you pull white, you can add appropriate amount of whitening agent in DP-2 can be evenly mixed can be printed; if the color pull, use DP-1 can add appropriate amount of whitening agent and paint color paste, stir well to use. Reactive dye discharge printing process is, before discharge, should choose easy to discharge reactive dyeing dyeing cloth; after printing, it is best to steam or press on the same day, in order to avoid long exposure of the printing surface air, so that Discharge failure; before steaming, pressing, do not laminate the printed fabric after each other to avoid causing the paste paste paste, even after steam press, should also be printed fabrics to cool and fully After drying, they can be stacked on each other; sometimes the main colors after washing are faded. The main reason is that the selected dyes and colorants are improper. If paint colorants are used, the amount of colorant must be increased and the drying time must be increased.
In the discharge printing, special attention must be paid to ensuring that the original dye on the cloth is suitable for discharging. After printing the discharge agent, the cloth must be cooked and dried, and the designed pattern can be printed in the discharged area. The effect of cooking can also neutralize the discharge agent to prevent it from damaging the fabric, otherwise large holes may occur when the ink is printed. Discharge printing is usually performed on a web-type rotary screen printer. The fabric of the process does not feel the ink, and the pattern is the same as the original one. More than 10 years ago, after technological innovation, the limitations of discharge printing were overcome, and the discharge printing was completely applied to the produced garments by applying the screen printing method. So that the discharge printing can be used for horsepower cloth can also be used for finished clothing, application more extensive and flexible. Clothing discharge printing can be regarded as a breakthrough in the discharge printing, especially in the field of manual plate printing, has achieved considerable development in recent years. Discharge printing for finished garments, also called printing, ie color discharge. The printing of garments generally uses screen printing methods to print a water-based printing paste containing a special discharge agent onto clothing. This printing looks the same as other water-based printing pastes printed on colored clothing. The next step is drying at a certain temperature. The discharge agent is activated by heat to selectively remove the dye from the garment and neutralize it so that it can express the color of the printed water-based printing paste. However, it is still a water-based system and must be completely dry (ie, the water content must be thoroughly evaporated), and the effect of discharge printing should be checked by cleaning. If the pattern fades, the drying time needs to be increased. The principle of color development of color discharge is that the discharge agent discolors the original dye on the fabric, and the color of the printing paste penetrates into the fabric fibers to give it a new color. Color discharge has the advantages of high production efficiency, good product feel, water-based color paste safety, and easy handling. Water-based inks are the most commonly used for discharge printing, and they are mixed with special activator powders that can remove organic dyes from the fabric. Use this method to ensure that the stencil material is water-resistant and the stencil is preferably waterproof. Discharge printing In the use of ink colorants, additives and other materials, should pay attention to the choice of other materials and operating techniques.
For screens, the number of screen lines is generally 50 lines. The best color density can be obtained with a 90T screen, and according to the characteristics of the fabric to be printed, excellent results can be obtained with a finer mesh. Dispensing printing must first print a white version (also known as a dark version). Its production method is to put four three-primary-colored Yang pictures together to create a negative version, which is a white version. In the positive plate exposure, the white plate is masked and the highlight area no longer needs the flash process. Discharge printing except black ink, other inks should be activated before printing. Pay attention to the quality of dyeing on the fabric or clothing so that the best results can be obtained. When garments pass through the dyeing device, due to the effect of heat on the active ink, the original dye in the printed area on the garment disappears, so that the pigment in the ink enters this region and the garment is printed. However, it should be noted that the dyeing and printing can only be carried out using garments that have been specially dyed for discharge printing. Discharge printing can use any device capable of handling water-based inks to cure the prints. In discharge printing, the dye on the fabric is destroyed by the dye discharge agent (activator) in the ink. So the dye is unstable to some extent. Discharge ink is water based and it is completely different from hot melt ink. Therefore, it should be noted that all screens and tools used should be cleaned after use; if the printing operation has to stop for several minutes, the printing plate must be kept moist. If done correctly, the printed clothing will not fade. Discharging the ink is absolutely safe for the skin. Once the garment is washed, any remaining chemicals are completely removed. Among the factors affecting the discharge effect, the effects of different fabrics are also different, and this also needs attention in the discharge printing. For example, the color phenol, the color structure and the direct effect on the cotton fiber have a great influence on the discharging. When the lake decomposition product has a dark color and the affinity for the cotton fiber is large, it is difficult to obtain a good whitening effect. The whitening effect is generally determined by the color phenol, and the relative stability of the azo component to the reducing agent is different. Although it also affects the whitening effect, it is subordinate to the former. Dyeing will affect the discharge effect, and the floating color will cause poor discharge. In order to reduce the floating color, it is important to control the proper ratio of chromic phenols, chromophores, and suitable chromogenic conditions, such as controlling the appropriate pH and adding suitable penetrants. In addition, post-processing should be fully washed, but it should not be vigorous soap. After the dye is dyed, the fabric is dipped in oxidizer and dried before printing. When printing and dyeing, due to the influence of the reducing agent, the earth color may be damaged to a certain degree during printing and steaming. This phenomenon is called embossing. Especially the old flower cylinder, the surface finish is reduced, easy to scratch, or even make the appearance of serious darkening or producing white hair. This relief can be prevented by eating oxidants.
In addition, pay attention to the