Basic principles of photochemistry of dye fading. During the sun exposure process, the effect of light on dyes can be explained from two aspects. First of all, as far as the dye structure is concerned, under the action of ultraviolet light, the chemical bonds in the dye are changed or even broken, causing the structure of the chromophore and auxiliary groups in the dye to be destroyed, thereby losing the color; it may also be under the influence of ultraviolet light Under irradiation, the three-dimensional structure of the dye changes, causing the color to change, which is manifested as color change. On the other hand, it is explained from the electronic structure and energy changes in the dye molecules. Under the irradiation of a large amount of ultraviolet light with higher energy, some bonding electrons gain higher energy and jump to higher energy level antibonding orbitals, or the electrons in lower energy level bonding orbitals jump to antibonding orbitals. . When these electrons return to their original orbits, they release different energies and show different colors from the original ones, thus showing different light fastnesses.
Factors affecting light fastness
1. And dyes Structure-related: Generally speaking, anthraquinone dyes, phthalocyanine dyes, sulfur blue sulfide and metal complex dyes have better light fastness; most insoluble azo dyes also have relatively high light fastness; and combined dyes have better light fastness. Aniline azo dyes have low light fastness; triarylmethane dyes are not light fast.
2. It is related to the type of fiber: ① Indigo is fast to light on wool but very low on cellulose; The light fastness on glue is much higher than on cotton.
3. It is related to the influence of external conditions: the humidity content of the air and the temperature also have a great influence on the light fastness. Generally, when the moisture content is high, the light fastness is low. For example: Vallamin blue is more likely to turn red and fade in the south than in the north.
4. Related to additives: There are many additives that can effectively improve the light fastness.
Measures to improve light fastness
Dye selection (the most important influencing factor) ① High light fastness in the yellow spectrum: Reactive dyes use pyrazolin and naphthalene trisulfonic acid as the parent structure; ② High light fastness in the blue spectrum: Reactive dyes Anthraquinone, phthalocyanine, and methyl ester are used as the parent structure; ③ The light fastness of red spectrum reactive dyes is generally low, especially light colors. Only two adjacent positions of some azo groups contain hydroxyl groups with coordination ability, and Copper forms a stable chelate ring, which can improve the light fastness; ④ When selecting dyes for color combinations, the light fastness level of each component dye must be equivalent. As long as any one of the components, especially The light fastness of the component used in the smallest amount cannot meet the requirements of light-colored dyeing, which will cause the light fastness of the final dyeing to fail to meet the standard.
Other measures
①The influence of dye floating color and incomplete soaping after dyeing. Unfixed dyes and hydrolyzed dyes remaining on the cloth will also affect the light fastness of dyed goods. Their light fastness is significantly lower than fixed reactive dyes. The more fully soaping is carried out, the better the light fastness will be;
② Cationic low molecular weight or polyamine condensed resin-based fixatives and cationic softeners should be used Fabric post-finishing will significantly reduce the light fastness of dyed goods. Therefore, when selecting fixatives and softeners, attention must be paid to their impact on the light fastness of dyed materials;
③Ultraviolet absorbers are often used in light-colored dyed materials to improve light fastness in recent times. However, it must be used in a large amount to have any effect. It not only increases the cost, but also causes yellowing and strong damage to the fabric, so it is not a good measure.
④Introduction to the plan for improving the light fastness
The light fastness improving agent FUNCTEX (Fix) F-5640 can Provides good light shielding effect on various types of fabrics and improves the resistance to sunlight and photolysis and fading of textiles. It is used to improve the sunlight fastness of dyed fabrics such as silk and wool dyed with acid dyes and cotton, viscose, linen and other fabrics dyed with reactive dyes. It can also be used to improve the sunlight fastness of dyed fabrics of polyester and its blended fabrics. Color fastness to light. It can also significantly improve the UV absorption performance of various fabrics.
Characteristics and advantages
1. The treated fabric can achieve good ultraviolet blocking effect.
2. It can reduce fading and enhance the light fastness of polyester disperse dyes.
3. Suitable as a light fastness enhancer for vehicle seat fabrics, decorative fabrics, etc.
4. This product has affinity for pure cotton and wool polyester fibers and can be absorbed during high-temperature dyeing.
5. Excellent emulsification stability, level dyeing and dye migration.
6. This product can significantly improve the light fastness of dyed fabrics;
7. During the treatment process, the treated fabrics The color light has little effect.
It can be effectively applied to cotton, linen (cellulose fiber) and nylon fiber fabrics, whether they are yarn, woven fabrics or knitted fabrics.
Process guidance can be used for dip dyeing and pad dyeing processes
1. Dip dyeing method: 20~40 g/liter Light fastness improving agent FUNCTEX (Fix) F-5640 liquid rate (70-80%) → pre-drying (105*C) 21 → baking (170°Cx60 seconds)
2. Dip method: 2-3% (o.w.f) sun fastness improving agent FUNCTEX (Fix) F-5640 is added to the same dyeing (including reactive, dispersed, acidic dyeing, etc.) in the same bath before dyeing at room temperature. To improve the sun fastness of colored fabrics. Note: It is recommended to test before use to observe its compatibility and stability.
Application fields
1) Improve the performance of various types of clothing and sportswear (such as running, football, Tennis, golf, sailing, etc.), beach, swimming and casual wear (T-shirts, shirts, tops, caps, etc.), work clothes and uniforms (military, postal service, police, school, etc.);
2) Improve the sunlight shielding and light resistance stability of professional textiles such as tents, canopies, awnings and parasols, other textiles used for shading and household textiles such as curtains. </p
