With natural dyes and pigments for dyeing the fabric has a long history in our country. People are already using the Shang and Zhou dynasties pulverized ore paiting color fabric. Qin and Han Dynasties sericite and lead sulfide have been used to stain. Meanwhile, blue grass, vegetable dyes such as madder and comfrey applications are becoming more common. Wei's "Qi Min Yao Shu" on the records of the dye was prepared "to kill safflower Law" and "making indigo Act." Ming and Qing dynasties, China's natural dye preparation and staining techniques have reached very high levels. In addition to self-dye, but also a large number of exports.
Mid-19th century and the advent of synthetic dyes into China in 1902, because of its shade and color fastness and other aspects of superiority, making natural dyes dyeing application in plants have been gradually replaced by synthetic dyes. However, in recent years, as people's awareness of environmental protection, production and application of synthetic dyes in the process of bringing the pollution problem has drawn increasing attention in the global green revolution, the natural dyes began importance for the people.
2, a new source of natural dyes
It is generally believed that natural dyes are derived from plants, animals and minerals, which went mainly vegetable dyes. However, it is now found in bacteria, fungi, mold and other microorganisms can also be used as a natural pigment dye source. British researchers said: palmate leather bacteria, fungi coarse fiber large hole monocytogenes can be used as a natural dye staining.
2.1, with the bacteria staining dye
Japan Institute of Agricultural Technology and insect silk silk trading cooperative research and found to produce purple pigment used to stain microorganisms make it . This organism is bred from silk waste in bacteria, Bacillus violet as Jensen mold pigment. The main species that produce pigment violacein and deoxy violacein. Jensen mold pigment violet non-pathogenic bacteria. Therefore, this pigment is safe. It can be divided into cells staining staining staining and the extract. Cells staining cells is suspended in water or a liquid medium, the fabric was immersed in the suspension 2h ~ 12h. Or cells placed in the pot with the agar medium, add boiling water, and then the dye the fabric was immersed in 80 ℃ 3min. Staining extract is extracted with methanol, tetrahydrofuran or a dye is dissolved in methanol or ethanol, and the fabric was immersed in a solution dissolving 2h ~ 12h. After staining, simply fabric washing, dry.
Not only can this pigment dyed cotton, hemp, silk, wool and other natural fibers can also be dyed nylon and other synthetic fibers. In addition to textile dyeing, but this technique can also be used in cosmetics and food coloring.
22, with the pigment stain fungi
Red yeast rice, also known as red rice, is rice Monascus inoculated into the culture. For the manufacture of red wine and red fermented bean curd, and it also used as a food coloring, medicine can be used for activating blood circulation. Red yeast rice pigment does not dissolve in water, the main component of the pigment is rubropunctatin and monascorubrin, orange and red, with fluorescence. Our researchers always try to use red yeast stained beige silk , will be placed with red yeast rice and acetic acid, the dye and other additives peregal heated to 60 ℃, the silk into the dye, heated 1h , remove washing, dry. With red yeast rice can be dyed in beautiful crimson silk.
3, a new method to extract natural dyes
The majority of natural dyes are vegetable dyes, pigments were present in their flowers, fruit, bark, stems, leaves and roots, how to extract natural dye pigment is applied when the first problem to be solved. Most plant pigments are water-soluble, so the vegetable dyes generally directly extracted with water. The dye-containing portion of the plant after grinding soaked in water a certain time, and then heated to boiling 20min ~ 30min, the resulting solution is dye. However, the dye bath is thus obtained a large size, the impact fastness.
In order to improve the performance of dye extraction, the researchers used ethanol instead of water as a solvent. The plant dye and after grinding, into a closed container, into 95% ethanol, immersed for 24h, the solution was poured out, and then impregnated with the same alcohol 6h, repeated twice. Finally, all the solutions were mixed and filtered, to a dye. This method is particularly suitable for those water insoluble dye.
Current research has shown that using ultrasonic method for dyeing processing, can improve the dyeing effect. The principle is: the use of ultrasonic dispersion of the cavitation in the liquid surrounding the micro-bubble generating thousands of atmospheres of pressure, the dye solution polymerization, to obtain a dye micro-particle, to improve the dyeing effect.
Some researchers use ultrasonic extraction of catechin dyed wool . The processing of the remaining poor Fu brick tea leaves, stems, etc. with water placed in an ultrasonic generator, hard rate of 25Hz 2kW ultrasonic treatment 30min, cooled to the residue filtered and the filtrate was concentrated to dryness derived dyes. UV spectrophotometer conventional method and the same concentration of catechins ultrasonic extraction test results showed that the catechins extracted by ultrasonic method than with the conventional method of extraction of the particle size is much smaller. Thus, the ability to enhance its penetration, combined with wool firmly. Contrast dye test results also indicate that ultrasonic extraction of the dye fastness, washing fastness and perspiration than conventional extraction method has greatly improved, reaching 3 to 4.
4, a new method for preparing dye
Traditional dyeing method is applied directly after the extraction staining dye, natural dye but some solubility in water, in order to achieve a certain dye depth, often require several dye. Tests showed that use of such dyes plus dispersant method, the effect is very good. An anionic or non-ionic surfactants in the dye to be dispersed dye particles, so that the dye may form a stable dispersion system, and the fabric, and increases the chance of contact with the dye, the dye rate is accelerated. The smaller water-soluble dyes, dye dispersant effect of adding more obvious.
5, mordant new advances in
Natural dye for dyeing cellulose fiber is low, the affinity of the protein fibers larger, but still much lower than synthetic dyes. Therefore, when natural dyes are normally used mordant, in order to increase the dye uptake. Traditional multi-copper mordant, iron, aluminum, chromium and other metal salts. Today textiles heavy metal ions has been restricted, it is necessary to develop new mordant replace traditional heavy metal ions.
Workers with our dyed earth - citrate complex as a natural dye mordant dyeing of ramie fiber test . The wetting of the fabric with natural dyes into the dye bath boiling dye 30min, cooled to 70 ℃, mordant added then heated to boiling, dyeing 30min, after removing treatment, the indicators measured. Experimental results show that a rare earth - citric matchmaker agent, dyeing depth and fastness are improved, the fabric dyed with a higher pH value of shade stability.
Rare earth - citrate complex is a natural dye mordant for dyeing the fabric, a natural dye - RE - Fabric three processes form a stable complex. Rare earth ions can be used as central ion and a ligand dye ion complexation. In addition, it has the role of electrolytes, could promote dyeing. Cellulose fibers treated with the surface pores of varying sizes, which can be rare earth ions into the fiber of the amorphous crystalline region and even the edge of the dye molecules and the formation of multiple complex cellulose molecules, thereby improving color fastness. The formation of this diverse complex system to fight because of the dye solution pH fluctuations arising from changes in shade.
6, the application of new progress in the field of
Since the advent of synthetic dyes, natural dyes has been phasing out the field of fabric dyeing, synthetic fibers occurs, natural dyes has been rarely used in fabric dyeing, so the only natural dyes for dyeing practice cotton, hemp, silk, wool and other natural fibers dyed . In recent years, as people on the upsurge of interest in natural dyes, people began to try to use natural dyes synthetic [4-5].
6.1, polyester fibers with natural dyes
Madder, comfrey and rhubarb and other natural dyes are anthraquinone pigment structure or naphthoquinone, and is very similar to the structure of disperse dyes. Their molecular weight is small and hydrophobic. These types of dye used for dyeing polyester fiber test, the adsorption isotherm in accordance with the Nernst disperse dyeable polyester isotherm, suggesting that these natural dyes disperse dyeable polyester similar mechanism.
Japanese researchers with onions, shellac and turmeric, ferrous sulfate as a mordant in dyeing polyester. The fabric was immersed in mordant solution, heated to boiling 45min, dehydrated and stained. Staining can be divided into high-temperature high-pressure method and an open bath and French liquor ratio of 1:40. Temperature high-pressure dyeing at 130 ℃ 45min, the open-bath dyeing at 100 ℃ 45min. Washing after dyeing, fixing under acidic conditions, and then washed with water, soap making. Test results show that the light fastness of dyed fabrics of 3 to 4, soaping and sublimation fastness of 4 to 5.
6.2, polyamide fibers dyed with natural dyes
Polyamide fibers containing amino and carboxyl groups available ionic dyes, such as acid and metal complex dyes, the adsorption mechanism is the Langmuir mechanism; also available disperse dyes. With comfrey, walnuts, etc. naphthoquinone type of natural dyes, its adsorption mechanism is consistent with the Nernst disperse dyeable polyester isotherm; while dyeing with annatto, because pigment is a linear ionic molecule, apart from the emergence one kind of mechanism, but are the dominant mechanism Langmuir.
6.3, using natural dyes polyacrylonitrile fibers
HuangBo natural dyes contained berberine is currently the only known natural dyes cationic dye. It can be used to dye polyacrylonitrile fibers. Thermodynamic results showed that: the coloring mechanism the Langmuir adsorption isotherm. This suggests that the positively charged and negatively charged dye may form an ionic bond fibers, the dye adsorbed on the fiber.
Flora and fauna in natural dyes dyes extracted from the organism, and good environmental compatibility, biodegradable. Although the distinctive bright synthetic dyes, natural dyes elegance but also synthetic dyes can not be compared. In addition to staining features, natural dyes also have drugs, spices and other features. Natural dyes are mostly traditional Chinese medicine, in the dyeing process, pharmaceutical and flavor ingredients together with fabric dye absorption, so dyed fabric drugs on the human body has a special health care function. China has abundant resources of natural dyes, dyed with natural dyes has a long history. In the natural dyes have unique physical and technical conditions. We should dig and carry forward the traditional technology, so that flourish in the 21st century.