Note 丨 cotton / brocade fabric dyed bright light-colored practical technology (dye factory recommended reading)

Cotton / nylon-based fabric, cotton yarn as warp system, spandex + nylon yarn as weft yarn woven outer fabric color single pin in a large proportion, the higher quality requirements, in which light is usually required Three high:

1. High light fastness to color

The requirement for light fastness for light-colored single-color lighters for export is usually AATCC US standard level 3 or higher (equivalent to IS0 105-B02 International Standard 5) This high requirement is often difficult to achieve in conventional production .

There are two reasons:

(1) In the case of light-colored dyes, the dyes are present in a highly dispersed state on the fibers , and the specific surface area in contact with air , moisture , and sunlight is relatively large , and the dyes are liable to be damaged by sunlight. Therefore, the lighter the color and the worse the light fastness . (Note: when dyeing dark dye mainly in the form of aggregates in the presence of the fibers, exposed to air, moisture, specific surface area is relatively small daylight, the degree of damage to dyes sunlight is relatively weak, so that the deeper the color, The better the light fastness is.)

(2) In the common medium-temperature reactive dyes: yellow reactive dyes, mostly mono-azo dyes synthesized with pyrazolone, pyridone or 2-aminonaphthalene-3.6.8 trinaphthalenesulfonic acid as coupling components. The dye contains an electron-withdrawing group (such as sulfonic acid group, halogen, and an electron-containing heterocyclic ring) at the ortho and para positions of the amino group. Due to the inductive effect of these electron-withdrawing groups, the density of the electron cloud of the nitrogen atom on the amino group is reduced.

Thus, the azo group has a high light stability and is not easily decomposed by photooxidation, and its light fastness is generally good. Such as active yellow 3RS, active yellow M-3RE, active yellow A-4RFN, active yellow FN-2R, etc., when the depth of dyeing 0.3% (owf), the light fastness can reach IS0 105-B02 blue standard about 5 grade . Red reactive dyes, mostly H-acid coupling components, azo dye structure due to the adjacent hydroxyl (-OH) and amino (-NH.) And other electron-donating group, the electrons on the nitrogen atom The relatively high cloud density makes the light stability of the azo group greatly reduced, and the photooxidation reaction is relatively easy to occur. Therefore, the red light-fastness of reactive dyes is generally relatively poor, when light-colored, light fastness is usually only IS0 105-B02 blue standard about 2-3.

The dark blue reactive dyes are mostly bis-amine dyes synthesized with H-acid as the coupling component. In the ortho-position of the azo group, though there is an electron-withdrawing group-(S03 Na) , due to the H-acid With the influence of the electron-donating hydroxy group (-OH) and amino group (-NH2) being introduced, the electron cloud density of the azo nitrogen atom is not reduced but rather high. Therefore, such dyes have poor light stability and low light fastness. When light-colored, the light fastness is only ISO 105-B02 blue standard 2-3.

Phthalocyanine blue reactive dyes, mainly active cuilan. Because of its copper complex structure, its light fastness is acceptable. When light-colored, the light fastness is about IS0 105-B02 blue level 4 or so.

The reactive dyes of the lanthanon blue type, whose mothers are mostly acid dye structures, their light stability is mainly dependent on the strength of the α-amino basicity. The stronger the alkalinity, the more easily it is oxidized to hydroxylamine (-NHOH) and the worse the light fastness is. Such dyes usually have such a structural feature that a strong electron-withdrawing group (-S03 Na) is introduced in the ortho position of the α-amino group. Due to its electron-withdrawing effect, the electron cloud density of the α-amino group is low and the basicity is weak. It is not easily oxidized to hydroxylamine, so the light stability of these dyes is good. The light fastness to light-colored light can generally reach IS0 105-B02 blue standard around grade 4.

Methylene blue reactive dyes, although having an azo group (-N=N-), but due to its copper complex structure, influenced by metallic copper, the photo- stability of the amino group is good. Therefore, these blue reactive dyes have relatively good light fastness, a depth of 0.5% (owf), and a fastness to light of IS0105-B02 blue level 5. However, there are not many such blue varieties.

It can be seen that the light fastness of commonly used medium-temperature reactive dyes is generally poor, and the requirements for light-colored products cannot be achieved. Therefore, when dyeing light-colored colors for export, reactive dyes with high lightfastness, such as Huntsman's disseminated ternary colors (yellow FN-2R, red FN-2BL, and blue FN-R), must be selected; Immersion type ternary color (yellow 3RS, red LF-2B, blue BRF) and so on. The dyeing cotton with these reactive dyes has excellent light fastness, and the dyed light color (0.3% owf) can also reach lS0 105-B02 blue standard 5 (equivalent to AATCC standard 3+). Therefore, it is very suitable for light and light color with high light fastness and light resistance.

2. High-brightness requirements for colored light

Difficult to dye high-light color, single color selection, dyestuffs may not always be able to meet the requirements, but also must maximize the end of the cloth (semi-finished bleaching) of the whiteness. Practice has proved that the quality of the base fabric whiteness, is a major determinant dyed bright shade of good and bad factors.

However, most of the cotton/nylon fabrics are currently treated by the enzyme-chlorine-bath cold-rolling process, and the whiteness often does not reach the maximum. We must do it again multiplexed oxygen bleaching dyed, semi-finished products to further improve the whiteness high to effectively enhance the brightness of the shade.

3 high requirements on the surface finish

Businessmen on the quality of the appearance of dyed products require high, oil must be clean, smooth. However, due to poor heat resistance of nylon, low softening point (160-180 deg.] C to Kam nylon 6, nylon 66 was 235 deg.] C), also a low melting point (215-220 deg.] C of nylon 6, nylon 66 250-265 ℃). Once the dry heat treatment temperature is high, it is prone to "paper" of (strong power drops, the elastic force disappears, hard texture, color and yellowing), or even loss of use value.

Thus cotton / nylon fabric is not pre-class singeing, usually before dyeing, the enzyme "polishing" the cotton fiber fluff removed clean, in order to improve smoothness and brightness of shade cloth.

From the graph it can be seen that conventional processes: conventional treatment process step, has a large energy consumption, emissions, low yield and high cost of defects, does not meet today's "energy, emissions and efficiency" dyeing concept. Therefore it is necessary to reform arts workers to oxygen + oxygen bleaching, polishing, dyeing one bath new technology substitution.

As can be seen from the new technology curve: use of oxygen Novozymes, polishing enzyme (Cellusoft Oombi), you may be oxygen, polishing, dyeing in a bath to complete the "energy saving efficiency" obvious advantages.

Cotton / brocade fabrics are dyed light-colored and this process is suitable for dyeing single reactive dyes. This is because: Unlike nylon and polyester, the structure of nylon is much looser than that of polyester, and its moisture absorption capacity is 10 times that of polyester. Therefore, the glass transition temperature of polyamide is very low (35-50°C for nylon 6 and 47-50°C for nylon 66), and the glass transition temperature in water can even be reduced to room temperature. Therefore, commonly used medium-temperature reactive dyes, under the condition of cotton dyeing at 60°C (mainly in the color-adsorbing stage), have different staining and coloration phenomenon ( see Table 1).

Table 1 Retardation of Nylon by reactive dyes under dyeing conditions

Origin