Due to the increasing demand of customers for the quality of fabrics, especially the large number of orders for dark, multi-color and fine patterns, the difficulty of fabric processing has increased. After many years of production practice, we have concluded a set of relatively mature printing process for coating anti-printing reactive dyes (abbreviated as “painting and prevention”), so that the appearance quality and intrinsic quality of the fabric can meet customer requirements, and the product quality is stable. Gained good results.
2 test materials and process flow
Fabric 30×3068×68 fine cloth
Process opening → Singeing → Retort → Mercerized → (smeared) → Printing → Steaming → Washing → Soaping → Finishing
Two positive and two negative, the speed of 100 ~ 110m/min, requires four. To avoid producing a large amount of hair during processing, cause blocking when printing.
2.1.2 Decoction and bleaching
Due to the use of anti-processed flowers, most of them are large-area ground-colored flowers. They are uneven and unrecognisable. They can easily cause variability in color, color, and uneven color. However, the effect is too high. Drying room, reactive dyes are likely to produce migration, but also cause ground color hair, and reactive dyes easily into the fiber and the fiber fixation reaction, affecting the anti-printing effect. General requirements of the effect of 8 ~ 12cm/30min.
Most of the patterns processed by the anti-grafting technique are deep-colored flowers. The cotton fabrics that are not mercerized can easily cause the reactive dyes to have a light color and dark shades, as well as waste of dye. The semi-product pH is required to be maintained at about 7 and should be uniform. Semi-finished printing products require a shrinkage of less than 3% to allow for flowering and, if necessary, preshrinkage treatment.
2.2 Rotary screen printing
2.2.1 Established printing process
The size of the borrow line is established according to the pattern of the flower and the relationship between the colors. The application of anti-smearing process is mainly to solve the following problems:
(1) The opposite color of shades of color When the flowers are overprinted, the third color is easily generated. After the anti-grafting process is adopted, partial overprinting is generally used to solve the problem.
(2) Fine flower patterns are difficult to flower. When using the borrowing line, a slight flickering of the flowers will cause a rag, and adopting all overprinting can greatly reduce the difficulty of flowering;
(3) If overprinting is used for light-colored patterns, color transfer will occur easily, resulting in blemishes. The application of a coating process will solve the problem of color transfer.
2.2.2 Anti-dye agent
When cotton fabrics are printed with reactive dyes, they cannot be dyed under neutral conditions, but under alkaline conditions (adding baking soda), the fibers can react with the dyes, thus preventing the reaction from taking place, both physical and chemical. method.
Anti-dye agents can be divided into two types, mechanical anti-dye agents and chemical anti-dye agents. At present, the mechanical anti-dyeing agent used in our factory is mainly white coating and overprinting white, and the chemical anti-dyeing agent is mainly ammonium acid sulfate.
The mechanical anti-dyeing agent relies on the isolation fiber dyeing seat to prevent the reactive dye from contacting the fiber, so that it can not be dyed, so as to achieve the purpose of anti-dying, the amount of which is larger, according to the appropriate color depth adjustment, the general amount of 10% to 40%. The chemical resist is neutralized by the acidity of the resist to neutralize the alkali soda which is dyed by the reactive dye, so that the reactive dye cannot bond with the fiber, thereby achieving the purpose of dyeing. If the amount is too small, it will not achieve the purpose of anti-dying, and the color will be dark; if the amount is too large, it will produce “dark side”, that is, the effect of over-protection. The theoretical amount can be determined by the following formula:
The ratio of ammonium sulfate to baking soda is 0.78:1, which can be adjusted according to the amount of baking soda and the anti-printing effect in actual production.
2.2.3 printing process prescription
(1) Active color paste
Anti-stain salt S1
Baking soda 1~3
Sodium alginate paste amount
Add water synthesis 100
Method of Dyeing: The dye, anti-staining salt S and urea are opened with hot water, filtered into sodium alginate paste, stirred well, cooled to 30° C., added with cold baking soda, and mixed well. If the amount of dye is too large to be completely dissolved in a certain amount of urea solution, the dusting method can be used to throw the dyes into the high-speed stirred urea and anti-staining salt solution one after another.
(2) color anti-plasma
Appropriate amount of coating thickener
Ammonium sulfate 0.6~1.5
Add water synthesis 100
Material method: The binder is diluted with water and added to the paint. Water and paint thickener are added under stirring. The total amount and color paste viscosity are adjusted. Finally, ammonium sulfate with cold water is added, and the mixture is stirred well. White pulp is the same practice.
2.2.4 Quality Control
(1) The coating color paste should be thick enough so that the anti-printing effect can be improved. When preparing the colorant, the amount of water should be compressed as much as possible.
(2) The overprinting white is a mechanical anti-dyeing agent, which has an obvious effect of assisting prevention. It can also be added in the color anti-slurry, but it has an effect on the coloring amount of the color coating. Due to the fact that overprinting of white and white paint on the doctor blade is a major concern, replacement of the blade should be performed during mass production.
(3) Anti-pigment and anti-white paste should not be added with cationic cross-linking agent (such as cross-linking agent EH) to prevent the adsorption of negatively-charged reactive dyes and cause contamination, affecting the vividness of colors, and if necessary, adding Aldehyde-free resin NF21 or softener CGF to improve fastness and improve fabric feel.
(4) The binder should be an anionic or non-ionic binder that does not adsorb reactive dyes and sodium alginate. It must be resistant to strong electrolytes (such as ammonium sulfate), and it is required that the film be fixed by steaming. After the adhesive film has a certain degree of water repellency, it can prevent reactive dyes from entering the interior of the fiber and act as a mechanical anti-staining effect.
(5) Tartaric acid or citric acid may also be used as the resist. Citric acid has strong alkali resistance and its concentration is 3% to 5%. However, when the pattern area is large, it will affect the fabric strength. Therefore, the fabric should be prevented from staying on the drying cylinder. Tartaric acid is more moderate, it is used for resisting dyeing in medium and light colors, and it can obtain clear-cut flower pattern effect. The dosage is generally about 6%.
(6) As ammonium sulfate is used as a small molecule inorganic compound, it can be dissociated in the color proofing paste. When the amount of resist is large, it can be permeated into the surrounding of the color proofing pattern to make the reactive dyes. Can not be dyed, but the paint slurry can not be osmotic, so as to form a circle of dew, so in the production of strict control of the amount of ammonium sulfate. A new type of anti-dye agent (CLEANTEXPWC) has emerged on the market. Its osmotic performance is comparable to that of a coating and can avoid such problems.
(7) After printing, the fabric must be dried so as to prevent the color from being peeled off and the anti-printing effect can also be improved.
(8) If the anti-printing area of the paint is large, the baking should be increased after steaming to improve the fastness;
(9) If dyed cloth is used for printing, alkali chemicals should be added to the ground and the amount of ammonium sulfate should be increased in the anti-print paste;
(10) The amount of urea in the active slurry should not be too much, so as to avoid urea moisture absorption during steaming and affect the adhesive conjunctiva, affecting the anti-printing effect and fastness;
(11) Thickeners should be thickeners with good acid stability;
(12) Anti-dye agent Ammonium sulphate is not easy to decompose during drying, and does not cause fabric damage; however, ammonium sulphate should not be used with hot-water sizing agent when preparing color paste, otherwise, ammonium sulphate hydrolysis will increase acidity and affect color paste stability. .
Steaming temperature 102 ~ 104 °C; time 7min. Humidity should not be too large, otherwise it will affect the filming of the binder, which will cause some reactive dyes and auxiliaries to transfer to the surface of the fiber and diffuse into the fiber to react with the fiber to fix the color. This will make the anti-printing effect worse, even if the amount of ammonium sulfate is very high. , The pattern has been exposed white lines, there will be irrepressible phenomenon.
Most of the reactive dyes in the anti-printing area exist in the form of hydrolyzed or unfixed, and must be washed with water and soaped.
After fabric printing and steaming, after several washings, the product’s fastness can meet the requirements of the national standard. After finishing the resin finishing agent, the product’s fastness can be improved by half and the product quality can be guaranteed.