1 Printing process of spandex-containing knitted fabric Weaving open-width printing → Loose cloth → (steaming) → pre-setting → pre-treatment → (dyeing) → printing → steaming → washing → dehydration → drying → setting.
2 Disposing of color separation design draft Computer color separation drawing, first according to the type of fabric, the size of the elasticity, the return of the pattern, the number of sets, the printing method (direct printing, printing, anti-imprinting), multi-level color depth, As well as scaling the artwork to specifications that meet production requirements.
2.1 Printing size scaling Under the allowable conditions of return, according to the different fabrics of spandex content scaling size, formulating printing speed, maintain the pattern after printing. When the spandex content in the general cotton spandex is between 3% and 5%, the warp direction of the pattern is enlarged by l3% to l8%, and the weft direction can be reduced by about 3%. When the spandex content is 6% to l5%, the pattern is The magnification is 20% to 26%, and the weft is reduced by about 5%. The proportion of warp magnification should take into account the speed of the printing speed, so while drawing the drafting process, we must consider the conditions of the entire printing process. At the same time as the drafting, various parameters of rotary screen printing have been established. The printing speed of the above data is controlled between 30 and 40m/min. If the printing speed is above 50m/min, the warp elongation ratio of the flower shape is more required, but the general printing speed is below 40rn/min, regardless of the flower shape. It's easier to control quality.
2.2 Discoloration of patterns in different printing processes during computer color separation Compared with woven fabrics, knitted fabrics are looser and have better permeability. Therefore, when dealing with drawings, there is a slight difference from the woven cloth printing. In the dyestuff direct printing of knitted fabrics, the permeability of the printing paste is relatively good, generally 8 ~ 16 silk complex color, in the case of mechanical accuracy of the printing equipment allows, to 8 wire, to ensure printing accuracy, while processing stack When printing, try to reduce the full three-color cover to prevent printing pressure paste; anti-print printing coating with anti-activity and activity anti-activity, coating anti-activity process, because the paint printing edge is not easy to open, printing paint points The color draft, the size according to the requirements of the color draft, and active over the cover full of paint; active anti-active printing, anti-printing of the set of monochrome draft must be incorporated into 8 to 16 silk, so that the printed pattern and color Correspondence with the manuscript; pull-printing, the color of the border with the color of the edge, you must close a small 16 to 24 wire, pull the color of the print to try not to cover each other complex color, but you can cover the white part of the overall The color of the colored part can increase the color brightness of the printed part, and it will not produce the white side caused by the printing. In addition to the above requirements related to the printing effect, the general handling principle is to meet the spirit of the original, and the style of the painting is repeated on the cloth.
2.3 Taking into account the method of drawing the method of drawing the net is also related to the method of making the net. At present, companies use more ink-jet screens and wax-jet screens, and some still use film-making networks. Relatively speaking, the ink-jet network is slightly inferior to the precision of the wax-making system, because the ink-jet system is used to wet the ink at the room temperature and then exposed to the surface of the circle. The ink has a spreading process and affects the process. The accuracy of the artwork, scaled polychromatic, or monochrome edges must be considered for this reason. Of course, the temperature and humidity of the grid must be kept constant.
2.4 The purpose of the nickel mesh network selection According to the fineness of the flower pattern and the requirements for the permeability of different fabric thicknesses, the mesh of the nickel mesh is selected. The nickel mesh is an indispensable material for printing. Currently used nickel mesh meshes are 40, 60. , 80, 105, 125, 155, and so on. The permeability of nickel mesh is an important indicator. Of course, the actual amount of slurry is also related to the viscosity of the slurry, the size and pressure of the scraper or magnetic bar, the printing speed, and the fabric. However, compared with the woven fabric, the knitted fabric has a rougher cloth pattern, so the same pattern is printed, and the mesh selected for printing the knitted fabric can be one size larger than the woven fabric. 50 meshes are mainly decorated with gold and silver grain printing, 60 meshes are used for large-area ground color printing, 80 meshes are used for coarser and bulky surface printing such as glue and water slurry, and l05 mesh is mainly used for fineness of leveling fabrics. Twist color, 125 mesh, l55 mesh is mainly used to print particularly fine patterns. If the terry cloth is a plush or velvet print, the fineness of the print will be affected by the texture of the fabric, and even higher meshes will not be able to reflect the effect of fine prints. The main consideration is the permeability of the print. the Lord. Therefore, the selection of nickel nets mainly depends on the specific conditions of each plant.
3 Pre-treatment methods for spandex containing fabrics 3.1 Preformed shape Since spandex is used to improve spinning performance, silicone lubricants and other additives are used in the weaving process. These additives will naturally degrade over time causing the fibers to yellow and the fabric's elasticity to decrease. At the same time, the spandex-containing fabric will form a "cold set" during long-term storage, resulting in a permanent wrinkle that cannot be eliminated during post-processing. Therefore, in addition to reducing the storage time, it is more important for the spandex-containing knitted fabrics to be opened immediately after weaving. Avoid the chance of creases.
Spandex-containing knitted fabrics have a certain amount of internal stress that is formed during weaving of the spandex inside the fiber. Therefore, the purpose of preheating and setting is to eliminate the stress through a relaxation process of the fabric, so that the size of the fabric is fully stabilized, and the permanent creases of the fabric in post-processing are eliminated. If the coil is formed when the cylinder is weaving, the second coil is on the left side of the first coil, and the feeding direction of the predetermined shape should also be 7% to 10% (relative width) in front of the left, which makes the twist of the finished product. be consistent.
Therefore, the best pre-formation plan is: relaxation → steaming (80°C hot water without steaming condition) → overfeeding pre-shaped → (pre-treatment of fabric → shaping → printing). Most dyeing plants directly push water into the shape because they do not have steaming equipment. When the temperature is below 10 degrees (in winter), creases are easily formed on the fabric. After the fabric is set through the steam box and then set, it will receive satisfactory results. The heat setting temperature is preferably between l85-190°C, and the setting time is 45-60 s. Setting too high a temperature will cause the fabric to yellow. At the same time, if the impurities and additives on the fabric are partially degraded due to the effect of baking, the degradation material once migrated to the inside of the fiber to produce marks, then these marks are difficult to remove in the subsequent processing, and the oil spots inside the fibers during dyeing The dyes will be absorbed first, but they will not be able to run out in time during dyeing and dyeing, resulting in the formation of dark spots. Even if they are re-stained and re-stained, they will remain on the fabric. Therefore, do not avoid high temperatures above 195°C. It also affects the fastness of spandex. The width of the set is 10% to 15% wider than that of the blank, so that it has a full recovery in the pretreatment of the dyeing tank, so that the internal stress of the fabric is completely eliminated.
3.2 Pre-treatment The knitted fabric to be printed must also be pre-treated to remove cotton stains, wax, etc., increase the whiteness of the fabric and improve the wetting and absorbing properties of the fabric, so as to achieve a good printing effect. The pre-treatment process can be divided into two major categories, namely the traditional alkali treatment and modern bio-enzyme treatment. The bio-enzyme treatment meets the requirements of environmental protection processing, but currently the fabrics with high requirements for whitening or bleaching are still difficult to meet the requirements, so the conventional The alkali treatment process is still widely used. It is necessary to gradually cool the spandex-containing fabric after the pre-treatment, and prevent the occurrence of creases caused by sudden shrinkage of the fibers due to shrinkage.
3.3 Setting of semi-finished products The setting of semi-finished products must be carried out according to the original design process. In general, the width of shaped shapes is 3% to 5% wider than the width of finished products, and the warp shrinkage rate is controlled within the shrinkage required by finished products. The stretch of the patch is equal to the scale of the drawing. If it is a single knitted fabric, then the control of the paddle trimming and optimal twisting is also needed to reduce the weft in the printing due to the twisting. The width of the pulp edge is about 1 cm, and the pulp breaks. Should not be too thin or too thick, too thin to achieve the desired effect, too thick will affect the printing effect of the near edge. The paint printing will increase the square meter quality of the fabric due to the solid slurry staying on the surface of the fabric. Therefore, under the conditions of width and shrinkage, the quality of the paint can be lighter.
4 operation method of rotary screen printing 4.1 When sewing seams, firstly check the front and back of the fabric. Before sewing the seams, we must first cut along the weaving line, align the two sides and lay it flat. The fabric after sewing with the copy machine is neat and tidy, easy to use. Machine printing.
4.2 Feeding and printing speed According to the performance of the spandex knitted printing fabric, choose heat-shrinking resin or cloth paste, adjust the cloth suction edger, edge stripper, vacuum cleaner, adjust the tension of the cloth, including spandex knitted fabric patch Tension is the minimum and the width of the cloth is reduced within 3% to 5%, and the vacuum cleaner is turned off. Into the cloth when the tension is uniform, the fabric is smooth, prevent slack. Spandex knitted fabric rotary screen printing, because of the fabric's elasticity is not only affected by the patch tension, but also affected by the speed of the speed. Therefore, even if there is almost no patch tension, the instantaneous tension caused by the change of the vehicle speed will cause the fabric to have different elongation. According to practical tests, when the printing speed is less than 20 m/min, the width of the patch is reduced by 1%~2. %, elongation in the direction of 3% to 5%: when the printing speed is 20 to 25 m/min, the width after the application is reduced by about 2%, and the longitudinal elongation is 5% to 10%: the printing speed is 30 to 35 m/s At min, the width of the patch is reduced by 2% to 4%, the elongation in the longitudinal direction is l2% to l8%, and when the printing speed is 35 to 45 m/min, the width of the patch is 4% to 6%, and the elongation in the warp direction 18% to 25%; when the speed is greater than 45m/min, the width of the patch is reduced by more than 7%. Of course, at the same time when the width is reduced, the warp direction will increase by a certain percentage. Therefore, the screen printing speed of spandex-containing knitted fabrics is suitable for printing speeds of 30 to 40 m/min. The excessively fast speed is not conducive to the control of product quality. What's more, the pattern return of rotary screen printing is subject to certain restrictions. Unlike flat screen printing, the return position of rotary screen printing is a fixed length system. The speed must be strictly controlled according to the proportion that has been enlarged. Otherwise, due to the variability of the size of the knitted fabric patch, the printed product will be deformed in size or even different from the horse. Therefore, the printing speed has been determined during the production of the rotary screen. , can not be arbitrarily changed in subsequent operations.
4.3 Rotary Screen Printing Pressure and Magnetic Bar (Scraper) Selection During printing, the height of the slurry in the mesh cylinder is moderate, and the fine stem and small area of ​​spent pulp are less, and the large surface pulp is more a little more. Carving prints are steamed every two to three hours to check the quality of the prints. It is also possible to indirectly fabricate a white cloth in a certain amount of grey cloth for the regular check of the quality of the print and quality of the rotary screen. According to the amount of sizing the fabric needs to control, select the pressure and magnetic bar (scraper), thin stem, small area pattern selection magnetic bar 10 or l2, scraper 45 ~ 50 cm; block surface selection magnetic bar 15 ~ 20 No., scraper 50cm; large surface printing choice magnetic bar 25, scraper 55cm. The size of the pressure varies from small stems to large ones, from small to large. In short, adjust the amount of sizing and penetration effect according to the performance of rotary screen printing machine.
Due to the fast speed of rotary screen printing, and the paste printing and printing printing is difficult to see clearly in dark cloth, the discharge printing with more than three colors is generally performed on flat screen printing machine, only one set or two sets are not available. The color accuracy of the carved printing can be printed on the rotary screen.
4.4 Formulation of the printing process The prescription of the printing process is determined by the dyeing performance of the dye on different fabrics. For example, direct printing of reactive dyes requires nothing more than a slurry (sodium alginate), a reactive dye, an alkaline agent (sodium bicarbonate or soda ash), and a hygroscopic agent (urea). The amount of the alkali agent and the moisture absorbent is very important, which is related to the ability of the dye to color and color the fiber and its effect. Therefore, according to different fabrics, the amount of additives used will also vary. In general, cotton or mercerized cotton is a little more than the amorphous area of ​​cotton, modal, bamboo fiber, etc. The dye is easy to enter the fiber, especially 3% to 6% of urea can be used; while cotton, modal, bamboo The crystallization zone of fibers such as fibers is much larger than that of cotton fibers, so the maximum amount of urea used must reach 25% in order to absorb the required moisture during the steaming and achieve normal hair color and good color yield. The ability of the K-type reactive dyes to color modal fibers is also relatively limited, and color shades are not achieved. P-type or PX-type reactive dyes can achieve good coloring performance.
4.4.1 Spandex Printing Fabric Active Process Table 1
Formula K-type dye Pushion PX/P Ciba P/PT
Adapt to varieties of cotton, cotton, cotton, modal,
Bamboo fiber cotton, cotton, modal, bamboo fiber sodium alginate paste (4%) 500
Thickener (2%) 200
Reactive dye X
Anti-stain salt S 10 10 10 10 10 10
Urea 30 to 60 150 to 250 30 to 60 150 to 250 30 to 60 150 to 250
Baking soda 10 to 30 20 to 30 10 to 30 10 to 20 10 to 30 10 to 20
Soda 0.5 5 ~ lO 5 ~ lO
Water Y
Total 1000
4.4.2 Discharge printing process a. Preparation and operation steps of pulp
Whiteness/%12 14 16 18 20
Starch ether syrup/g 330 320 320 290 270
Sodium alginate (5%)/g 350 340 320 330 330
White powder/g 120 140 160 180 200
Soda Ash/g 60 60 60 60 60
Sodium hexametaphosphate/g 10 10 10 lO 10
Salt/g 20 20 20 20 20
Water/g XXXXX
Total/g 1000 1000 1000 1000 1000
Operation steps: According to the prescription, the starch ether pulp and the sodium alginate pulp are first mixed, sodium hexametaphosphate, salt, water, etc. are added and stirred for 30-60 minutes. Then add the soda ash powder and stir the white powder until it is uniform. The prepared slurry was quantitatively analyzed by iodine droplet determination and recorded. In order to mix the correct fight. According to the need, each factory prepares several kinds of scouring pastes with different matching whiteness to create convenient conditions for brewing printing pastes.
b. Process prescriptions and operating procedures for various kinds of white pulp extraction
White carving carving whiteness /% 12 14 16 18 20
White pulp (white dextrin)/g 700 680 660 640 620
White powder/g 120 140 160 180 200
Water/g 140 140 140 140 140
Sodium hexametaphosphate/g 5 5 5 5 5
Soda Ash/g 60 60 60 60 60
Brightener/g 2 - 32 - 32 - 3 2 - 3 2 - 3
Chemicals Taibai / g 2 ~ 3, depending on the need to set, you can not add.
Flat add O/g 15, increase the smoothness of squeegee, can not increase the total /g 10OO
If neutral white is used, the amount of soda ash in the prescription can be reduced to 2%. Knitted vats of dyed white vats are used for the whitening of the base color. White liquors for bottom sizing can ensure whiteness, because starch ethers and sodium alginate all contain yellow pigments, which will affect The whiteness of the carved background, the use of white pulp will have the desired effect, but many printing plants have no boiled pot now, so if you directly use starch ethers or sodium alginate, you will not be able to reach the white dextrin The whiteness of the pulp, whitening agent in the whitening agent must be reducing agent and electrolyte.
The specific printing process has been described in detail in the previous article “Production Practice of Reactive Dyes Printing and Discharging of Pure Cotton Knitwearâ€, and is not repeated here.
4.5 Drying after printing The temperature of the drying room is strictly controlled. The coating is printed at a temperature of l40-150°C. At the same time, the adhesive is crosslinked at the same time as the drying; the active printing is about l35°C, and both sides are evenly dried if dried. The degree of difference, then steaming will also produce left and right color. Green, gray and other sensitive colors are more obvious; vat printing and printing 125 ~ 130 °C, not only to prevent drying and mutual color, but also to consider the temperature is too high to reduce the early reduction of dye and affect hair color. The printing of embossed printing with steaming, over long time stacking, will cause the dyes exposed on the air part of the fabric to oxidize first, resulting in a permanent color difference; for the printing of polyester fabrics with a smooth fabric, although there is a solid content comparison High paste, but does not rule out the possibility of pulp easy to drag, printing can not be squeezed after dragging, dragging or displacement, naturally falling into a heap, and then enter the evaporator steaming. Modal, cotton and other fabrics encountered reactive dye printing, into the steamer before the best spray to wet, so that the fabric temperature at room temperature, to maintain the color consistency and integrity.
4.6 Steaming and Washing of Spandex-Containing Knitted Fabrics Steaming with a continuous steaming machine is better than steaming tanks because if the steaming tank is steamed, the spandex knitted fabric will not only be stretched in the weft and heat during wetting. Long deformation, and some dragged to the bottom of the box, enlarged the disadvantages of the cylinder steam box that are prone to up and down, resulting in uneven steaming and hair color. In the steaming of the long loop steamer, it is also necessary to pay attention to the tension of the cloth, as long as it can drive the cloth into the steamer. The cloth should be flattened, especially the embossed printing. The cloth surface cannot be folded. Otherwise, it will produce blemishes, dragging and other defects in the process of steaming. K-type reactive dyes have a steaming time of 10 to 14 min, a temperature of 102°C, and a saturated steam inlet pressure of 0.4 to 0.5 MPa. P- and PX reactive dyes are steamed for 5 to 8 min at a temperature of 102°C and saturated steam is introduced. Steam pressure 0.4 ~ 0.5 Mpa; disperse dye steaming time 7 min, temperature 175 °C.
Spandex knitted fabric washing more than the general knitted fabric washing should pay attention to the entire washing process of the longitudinal force problem. The rope-shaped pull cylinder is the most traditional washing equipment and is more suitable for washing the knitted fabric. However, when it meets the engraved printing fabric, it will show the disadvantage that the fabric is always in a rope state, and inevitably produces a color. Therefore, continuous washing with a loose-type, flat-type, loose-type rope is currently a better knit washing machine, and the knitted fabric in the state of a flat web can spray the water, so that the slurry on the fabric can be easily expanded and washed off the fabric. After the alkali agent and a part of the floating color enter the rope soaping or reducing and cleaning process, a good washing effect will be obtained.
4.7 Elastic spandex knitted fabric after finished product shaped water elution water, the width is much smaller than the finished product requirements. The soft setting on the shaping machine is often less than expected, it needs to be dried in a loose dryer, let it shrink naturally, and then After over-feeding, the setting speed is controlled at about 20 m/min, allowing the fabric to be fully fed and over-shaped. Too fast a setting speed will cause the fabric to have a tight and uneven state on both sides. The setting temperature can be 135-160°C, because the final shape setting is given on the basis of the predetermined shape, and the excessively high setting temperature not only makes the fabric yellow or partially yellows the softener, but also causes the spandex to lose some elasticity. Bad effect.
5 Conclusion 5.1 Circular screen printing of spandex-containing knitted fabrics, especially discharge printing, has always been a production restricted area, which is related to the slight improperness from the processing of the color drafts to the printing, and the stability and twist of the dimensions. Issues such as weft and weft come in one after another, causing irreparable damage. Through our practice, this problem has now been solved, and rotary screen printing machines can fully print elastic knitted fabrics containing spandex.
5.2 Spandex-containing knitted fabrics During the processing process, the most important thing is to grasp the problem of no wrinkles in each process. This will require every step from weaving.
5.3 The requirements for the quality, width, shrinkage and twist of the final product containing spandex knitted fabrics must be grasped from the predetermined shape in addition to the requirements for weaving. Otherwise, the same weaving specification, due to different processing methods, will produce different grams of quality, width, shrinkage and twist. Predetermined width control and temperature and speed play a decisive role.
[Abstract] The printing of knitted fabrics developed rapidly within a short span of ten years. However, due to its dimensional stability, it is difficult to control during processing, making it difficult to develop rotary screens for knitwear, especially for cotton knit fabrics containing spandex. The knitted fabric itself has a large plasticity. When the fabric is fed with a drape weight and a cloth rack tension, it is also subjected to a change in the speed of the stretch. The shape and size of the pattern are more difficult to control and it is more difficult to meet geometric patterns. To maintain the original spirit of flowers, it is difficult to achieve satisfactory results. This must take the necessary control of the entire process in order to solve it.
The printing of knitted fabrics developed rapidly within a short span of ten years. However, due to its dimensional stability, it is difficult to control during processing, making it difficult to develop rotary screens for knitted fabrics, especially for cotton knitted fabrics containing spandex, apart from cotton knitted fabrics themselves. The plasticity of the size is large, the weight of the drapery itself and the tension of the fabric feeding frame when entering the fabric, and the tensile force of the vehicle speed change, the shape and size of the flower pattern are more difficult to control, and it is more difficult to maintain the flower shape when encountering the geometric pattern. Some spirits are difficult to achieve satisfactory results. This must take the necessary control of the entire process in order to solve it.