Search

What are the applications of disperse dyes?

Date:Nov 23, 2020

Background and overview

Disperse dye is a kind of dye which is insoluble in water (strictly speaking, slightly soluble in water) and forms a highly dispersed form in water by the action of dispersant. It is mainly used for dyeing polyester fiber. The chemical structure of most disperse dyes belongs to the monoazo type, accounting for about 80% of the disperse dyes, followed by the anthraquinone type accounting for about 15%, and other structural types accounting for about 5%. It is generally believed that the dyeing mechanism of disperse dyes in water is: due to the action of dispersants, at the dyeing temperature, part of the dyes are dissolved in the dyeing bath to become dye molecules, and then they are adsorbed on the surface by the fibers in the form of molecules, and at the same time they polymerize The amorphous area in the ester fiber expands at the dyeing temperature to form a cavity sufficient to hold the dye molecule, which makes it easy to diffuse the dye molecule in the fiber. At the end of dyeing, as the temperature decreases, the previously expanded cavity shrinks , The dye molecules are wrapped in the fiber, so that the dye molecules are finally fixed in the fiber in the form of single molecules or low-molecular aggregates. Some scholars abroad once believed that the crystal form (ie, crystal form) of disperse dyes has an effect on its dyeing performance, but later research results rejected this statement. However, the crystal form of disperse dyes is different, and its lattice energy is also different, so the crystal form of disperse dyes has an impact on its commercial processing.


Application

Due to the hydrophobicity of polyester fibers, the dyeing methods of disperse dyes generally include hot melt method, high temperature pressure method and carrier method. The hot-melt method is to first pad dye and dry the fabric, and then send it to a hot-melt machine to heat-melt and fix the color at about 200℃; the high-temperature press method usually expands the fiber at 120~140℃, so that the dye diffuses into The inside of the fiber is dyed; the carrier method is to add an organic carrier in the dye bath to make the fiber puff and guide the dye to penetrate into the fiber for dyeing.


1. Lifting power and fastness of disperse dyes for polyester superfine fibers

The development of polyester microfibers in my country, especially the island-in-the-sea polyester microfibers manufactured by the composite spinning method, makes the fabrics made of polyester fibers have the advantages of moisture absorption, breathability, softness, and good drape. A great improvement. The suede fabric made from it is very similar to natural suede. The output of polyester microfibers in my country has been increasing year by year, but the supramolecular structure of this fiber has undergone great changes, and its specific surface area is very large, which makes the dyeing rate and amount of disperse dyes for the existing polyester microfibers, New problems have appeared in the color rendering property, leveling property, lifting power and color fastness of dyes. Improving and improving the lifting power and fastness of disperse dyes for polyester ultra-fine fibers has become a top priority. At present, many large foreign companies have successfully developed new disperse dyes suitable for dyeing various ultrafine polyester fibers such as sea-island silk types and differentiated composite types, such as Lumacron MFB (M. Duowen Company ), Tiankun Skycron Ace, Kayalon Microester (Nippon Kayaku Corporation), DianixSPH and UPH (DyStar) and other dyes. Compared with foreign products, the disperse dyes for sea-island polyester ultra-fine fibers developed in my country still have a certain gap in lifting power, covering property, light fastness and wet fastness, which need to be further improved.


2. Fabric fastness performance requirements

In order to meet the increasing fastness requirements of polyester fabrics such as sportswear, casual wear and automotive interior fabrics, such as excellent washing fastness, the research and development of new disperse dyes should be strengthened. After polyester fabrics such as sportswear, casual wear and automobile interior decoration fabrics are dyed with disperse dyes, heat setting treatment is required to ensure uniform and stable dimensions of the finished product. As the heat setting temperature exceeds 140°C, the disperse dyes in the fiber will undergo thermal migration in the opposite direction to that of dyeing, and some dyes will re-migrate to the fiber surface, resulting in the color fastness of the heat-set polyester fabric after dyeing, mainly washing fastness. , Perspiration fastness, etc., will be contaminated on the adjacent lining, or pollute the environment. On the other hand, polyester fabrics after dyeing and reduction washing, especially polyester-cotton blended fabrics, need to be softened and waterproofed after finishing, and the finishing temperature is relatively high.


Many softeners and waterproofing agents currently available on the market, such as amino silicone softeners, are emulsified with emulsifiers made of nonionic surfactants. They are like carriers, which will dissolve disperse dyes, so that the dyed disperse dyes will not only undergo thermal migration due to high temperature during finishing, but also migrate to the fiber surface due to dissolution in the carrier, thereby reducing the washing fastness and washing fastness of dyed fabrics. Color fastness such as perspiration fastness. This migration occurs even during storage and transportation. So far, the color fastness to washing etc. measured for the disperse dyes produced in our country is the data after the polyester fabric is dyed with disperse dyes and then reduced and cleaned without heat setting treatment or soft and waterproof finishing. Thermal migration resistance of disperse dyes. Practice has proved that among the existing disperse dyes in our country, quite a few varieties, especially the red disperse dyes, have poor heat-resistant migration properties, which will make the color fastness of dyed polyester fabrics worse after heat-setting or soft and waterproof finishing.


3. New disperse dyes with high light fastness

In order to meet the requirements for light fastness of automobile interior decoration fabrics, military camouflage fabrics, mountaineering clothing and home decoration fabrics, the development of new disperse dyes with high light fastness should be accelerated. my country's automobile industry has developed rapidly, and the light fastness requirements of polyester decorative fabrics in automobiles have been continuously improved. This is also a major market for disperse dyes in my country in the future. At present, it is particularly necessary to develop a new type of super light fast disperse dyes that are adapted to the new daylight test requirements formulated by General Motors Corporation of the United States, the light fastness requirements of the International Automobile Manufacturers Association, and other test requirements. Tiankun Skycron HLF dyes have been launched in the international market. Research and development of this new type of disperse dye is a reference. In addition, there is a growing demand for new high light fastness disperse dyes suitable for dyeing military camouflage fabrics, mountaineering clothing and home decoration fabrics.


4. New high-performance disperse dyes

Starting from environmental and ecological requirements, accelerate the development of new high-performance disperse dyes that replace allergic disperse dyes and toxic disperse dyes. At present, my country no longer produces and uses internationally banned disperse dyes that can cleavage and release 24 kinds of carcinogenic aromatic amines. In addition, some of the important allergic disperse dyes in the international banned dyes are still produced and used in my country, including C. I. Disperse Yellow 3, C. I. Disperse yellow orange 13, C. I. Disperse Orange 76, C. I. Disperse Red 1, and Disperse Blue EX-SF300%, Disperse Black EX. SF300%, disperse black EX-SF150% (liquid) etc. There are also dispersants and other additives used in the commercialization of disperse dyes, because of the lack of strict control on toxicological indicators such as carcinogenicity and allergies, harmful chemical substances are introduced. For example, a wide range of dispersant MF is used. Due to the impure raw materials produced, many harmful fused ring compounds are contained in the finished product.


Since January 2006, the mandatory national standard GB18401-2003 for my country's textile industry has been officially implemented. It is mainly for dyes and auxiliaries. It is not only applicable to all textiles in my country, but will also be extended to export textiles. In the first quarter of 2006, my country's recommended national standards for ecological textiles were promulgated. Therefore, it is imperative to accelerate the development and further substitution of new high-performance disperse dyes for allergic disperse dyes and toxic disperse dyes.


5. New disperse dyes suitable for dyeing blended fabrics such as PES/PA

Because of the blended fabric composed of polyester fiber (PES) and polyamide fiber (PA). It has the characteristics of anti-white stripe dyeing effect, differential dyeing effect and same color shade dyeing effect. Therefore, in recent years, the interlaced fabric with polyester fiber as warp yarn and polyamide fiber as weft yarn is very popular in the market. In Asia, blended fabrics composed of polyester and polyamide two-component microfibers are widely used in man-made wool fabrics, silk-like fabrics, sportswear, ultra-high-density fabrics, and high-tech clean clothing. Development of suitable dye pairs It is important to dye it. Generally speaking, the disperse dyes used in the above-mentioned fabrics are required to have uniform lifting power for light colors; the staining of polyamide fibers during the one-bath dyeing process is low; when the two-bath dyeing process is acid reduction cleaning, the disperse dyes should have easy Detergency and reliability of dye bath exhaustion to prevent uneven dyeing. It is also researching and developing other fibers (such as spandex fiber, polyacrylonitrile fiber, cellulose fiber, etc.) that form a blended fabric with polyester fiber to use new disperse dyes with low staining properties and excellent dyeing properties. These are the technical issues that my country's disperse dye manufacturers need to solve.