How to improve the color fastness of digital printer fabrics?
The color fastness of digital printing fabrics is the key to measuring the quality of printing, which is directly related to the durability and aesthetics of the product. Insufficient color fastness will lead to fading and staining of fabrics, reducing the value of use. The following is an effective way to improve color fastness from multiple links.
Do a good job in fabric pretreatment
Fabric condition has a significant impact on color fastness. Natural fibers contain wax, pectin and other impurities, and synthetic fibers have oil on the surface, which will prevent the ink from adhering. Pre-treatment, neutral detergent can be used to soak the fabric for 30 minutes, and then rinse with water to pH 6-7, completely remove impurities.
Different fabrics need to be targeted treatment. Cotton and linen fabrics can be low-temperature plasma treatment or soak rolling hydrophilic agent to increase the surface roughness and hydrophilicity, so that the ink penetrates uniformly; polyester and other chemical fiber fabrics for alkali reduction treatment to remove the surface layer of skin, enhance the adsorption capacity. At the same time, control the moisture content of the fabric at 6% -8%, to avoid excessive moisture leading to ink diffusion or too dry to make the fiber brittle.
Reasonable choice of ink
The compatibility of ink and fabric is the basis of color fastness. Cotton, silk and other natural cellulose fibers, priority to reactive dye ink, its molecules can form covalent bonds with the fiber chemical reaction, color fastness to washing more than 4; polyester, nylon and other synthetic fibers, with disperse dyes ink, through high temperature sublimation so that the dye penetrates into the fiber.
Blended fabrics can use “dual ink system”, respectively adapted to different fibers. Select inks with high reactive groups and ensure that they are stored at 5-30°C and protected from light during the shelf life to prevent decomposition of the components from affecting the fixation ability.
Optimize Process Parameters
When printing, it is important to control the ink volume and layers. Too much ink will lead to ink accumulation on the surface of the fabric, easy to fall off, can reduce the pattern color saturation or reduce the number of printed layers. At the same time, to ensure that the nozzle spray uniformity, to avoid localized ink concentration.
Solid color link needs to be accurately controlled. Activated ink printing cotton and linen fabrics, steam color-fixing temperature 102-105 ℃, time 8-12 minutes, followed by cold water rinse to float color; dispersed ink printing polyester fabrics, high-temperature baking temperature 170-190 ℃, time 30-60 seconds, the temperature is not enough or too high will affect the effect.
In addition, the printing environment humidity control at 50% -60%, temperature 20-25 ℃, for ink penetration and adhesion to provide stable conditions.
Emphasis on post-processing and testing
Post-processing can strengthen the color-fixing effect. After fixing the color of the fabric should be fully washed, active ink printing can be rinsed with cold water, and then wash with neutral soap at 40 ℃ or less; dispersed ink printing with warm water to rinse the surface residual additives.
High color fastness requirements of the fabric, washing can be added 1% -3% of the color-fixing agent, to enhance the washability, but need to control the amount to prevent the feel hard. Regularly test the color fastness to washing and rubbing according to the standard, analyze the reasons for unqualified products and adjust the process.
Through the optimization of the above whole process, it can effectively improve the color fastness of digital printing machine fabrics, and enhance product quality and service life.
