Dr N.N.Mahapatra
C.Col FSDC ( UK),CText FTI ( Manchester ), FRSC ( UK ),FAIC(USA)
Business Head(Dyes)
SHREE PUSHKAR CHEMICALS & FERTILISERS LTD.
(301-302, Atlanta Center, Near Udyog Bhawan,
Sonawala Road, Goregaon (East )
Mumbai 400063. India
Innovation sees no limit and Indian consumers can expect something big coming up in the textile industry like fabrics and textiles woven from fine quality Ramie fiber. Ramie (pronounced Ray-me) is one of the oldest vegetable fibers and has been used for thousands of years. Ramie fibre is one of the oldest textile fibres .it was used in mummy cloths in Egypt during the period 5000 to 3000 BC and has been grown in China for many centuries. In the study of the “Lazarus” mummy, three types of textiles were found. The outermost cloth was heavy and coarsely woven; the innermost was the lightest and most tightly woven. The outer cloth appeared to be ramie (which Wiseman notes “contains non-fibrous material that is toxic to bacteria and fungi”—in other words, an ideal textile for mummy making). Farmers in ancient China are also known to have used the fiber to weave clothing. Ramie was used to produce an open weave fabric called mechera, used for shirts and dressing gowns suitable for warm climates. The French painter Raoul Dufy designed in the early 20th century patterns for prints on mechera used by the French shirtmaker Charvet. Brazil began production in the late 1930s with production peaking in 1971. Since then, production has steadily declined as a result of competition with alternative crops, such as soybeans and the important synthetic fibres.
Production of Ramie Fibre-
Ramie (Boehmeria nivea), commonly known as China grass, white ramie, green ramie and rhea, is one of the group referred to as the bast fiber crops. The ramie plant is a hardy perennial belonging to the Urticaceae or Nettle family, which can be harvested up to 6 times a year. It produces a large number of unbranched stems from underground rhizomes and has a crop life from 6 to 20 years. The fibers need chemical treatment to remove the gums and pectins found in the bark. Ramie is one of the oldest fibre crops, having been used for at least six thousand years, and is principally used for fabric production. It is a bast fibre, and the part used is the bark (phloem) of the vegetative stalks. Ramie is normally harvested two to three times a year but under good growing conditions can be harvested up to six times per year.[2] Unlike other bast crops, ramie requires chemical processing to de-gum the fibre. The process of transforming the ramie fibers into fabric is similar to the process used for manufacturing linen from flax. The true ramie or ‘China Grass’ is also known as ‘white ramie’ and is the Chinese cultivated plant. It has large heart shaped, crenate leaves covered on the underside with white hairs that give it a silvery appearance. Boehmeria nivea var. tenacissima is believed to have originated in the Malay Peninusula and is known as ‘green ramie’ or ‘rhea’. Green ramie has smaller leaves than true ramie and is better suited to tropical climates.
Extraction of the fiber occurs in three stages.
• Firstly, the cortex or bark is removed, either by hand or machine, in a process called de-cortication.
• The second stage involves scraping the cortex to remove most of the outer bark, the parenchyma in the bast layer and some of the gums and pectins.
• The third stage involves washing, drying and de-gumming of the residual cortex material to extract the spinnable fiber. Details of the de-gumming processes tend to be regarded as commercial-in-confidence information .
Harvesting is done just before or soon after the beginning of flowering. It is done at this time because at this stage there is a decline in plant growth and the maximum fibre content is achieved.[2] Stems are harvested by either cutting just above the lateral roots or else bending the stem. This will enable the core to be broken and the cortex can be stripped from the plant in situ.
After harvesting, stems are decorticated while the plants are fresh. If this is not done while the plants are still fresh the plants will dry out and the bark will be hard to remove. The bark ribbon is then dried as quickly as possible. This will prevent bacteria and fungi from attacking it.
The dry weight of harvested stem from crops ranges from 3.4 to 4.5 t/ha/year, so a 4.5 ton crop yields 1,600 kg/ha/year of dry non-de-gummed fibre. The weight loss during de-gumming can be up to 25% giving a yield of de-gummed fibre of about 1,200 kg/ha/year.
The extraction of the fibre occurs in three stages. First the cortex or bark is removed; this can be done by hand or by machine. This process is called de-cortication. Second the cortex is scraped to remove most of the outer bark, the parenchyma in the bast layer and some of the gums and pectins. Finally the residual cortex material is washed, dried, and de-gummed to extract the spinnable fibre.
The stems need retting ,which is controlled rolling by soaking in water and allowing bacteria to attack the stems . The fibres are then separated mechanically by scutching ( beating ).The fibres are bundles of many overlapping cellulosic cells and are much , stiffer and longer than cotton. The cells adhere by means of lignin cements.When combed Ramie is half the density of Linen , but much stronger , coarser , and more absorbent. It is reported to have a tensile strength eight times that of cotton and seven times greater than silk. The stems of Ramie grow to a height of 1 to 2.5 meters. It has a permanent luster and good affinity for dyes , it is affected little by moisture.
China leads in the production of ramie and exports mainly to Japan and Europe. Other producers include Japan, Taiwan, the Philippines, and Brazil.[7] Only a small percentage of the ramie produced is available on the international market. Japan, Germany, France and the UK are the main importers, the remaining supply is used domestically.[2]
Properties of Ramie Fibre – This is a natural woody fibre resembling flax . it is known as Rhea and China grass. It is stiff,more brittle than linen. It is highly lustrous and almost silk like appearance It is obtained from a tall shrub grown in South East Asia , China , Japan and Southern Europe. It can be bleached to extreme whiteness. The strength of Ramie is excellent and varies from 5.3 to 7.4 grams per denier.Elastic recovery is low and Elongation is poor. This is also used in making coarse grass cloth and for rope, twine,nets and clothing.
Ramie is one of the strongest natural fibres. It exhibits even greater strength when wet. Ramie fibre is known especially for its ability to hold shape, reduce wrinkling, and introduce a silky lustre to the fabric appearance. It is not as durable as other fibres, and so is usually used as a blend with other fibres such as cotton or wool. It is similar to flax in absorbency, density and microscopic appearance. However it will not dye as well as cotton. Because of its high molecular crystallinity, ramie is stiff and brittle and will break if folded repeatedly in the same place; it lacks resiliency and is low in elasticity and elongation potential.
Ramie fiber is one of the premium vegetable fibers. The ultimate fibers are exceptionally long and are claimed to be the longest of vegetable origin, with one report claiming the fibers range up to 580 mm, averaging about 125 mm. Ramie fiber is very durable, is pure white in colour and has a silky luster.
For the hand spinner, ramie is treated similar to flax in that it can be either wet or dry spun. A wet spun yarn will produce a smooth softer yarn with high luster, while a dry spun yarn will feel hairier, have less luster and a harsher handle. It can readily be blended with other fibers such as wool or silk, although the length of ramie can sometimes cause difficulties.
Advantages of Ramie
• Resistant to bacteria, mildew, alkalis, rotting, light and insect attack.
• Extremely absorbent (this makes it comfortable to wear)
• Dyes fairly easy.
• Natural stain resistance.
• Increases in strength when wet.
• Withstands high water temperatures during laundering.
• Smooth lustrous appearance improves with washing.
• Keeps its shape and does not shrink.
• Strong and durable (It is reported to have a tensile strength eight times that of cotton and seven times greater than silk).
• Can be bleached.
Disadvantages of Ramie
• Low in elasticity.
• Lacks resiliency.
• Low abrasion resistance.
• Wrinkles easily.
• Stiff and brittle.
• Necessary de-gumming process.
• High cost (due to high labour requirement in production, harvesting and decortication.)
The main producers of ramie today are China, Brazil, Philippines, India, South Korea and Thailand. Only a small percentage of the ramie produced is available on the international market. Japan, Germany, France and the UK are the main importers, the remaining supply is used domestically (in the country in which it is produced).
Blending of Ramie fibre –
Ramie is most often blended (common is 55% ramie/45% cotton) with other fibres for its unique strength and absorbency, lustre and dye-affinity. For example,
• Blended with cotton, results in increased lustre, strength and colour.
• Blended with wool, results in lightness and minimises shrinkage.
Chemical processing of Ramie fibre.-
Chemically ramie is classified as a cellulose fibre, just as cotton, linen, and rayon.
Pretreatment It is done as follows.
1. Ramie fibre is loaded into the fibre carrier.
2. First a low foaming wetting agent and detergent with emulsifying , dispersing and extractive action .( 1 gpl ) was added in the m/c and circulated for 5 mins at room temperature..
3. Raise temperature to 60 deg c then add Caustic Soda Flakes ( 3 gpl ) , Hydrogen Peroxide ( 50 % ) –2 gpl and a silicate free stabilizer for alkaline peroxide bleaching. Run for 10 mins.
4. Then raise temperature to 95 deg c at the rate 2 deg per min.run at 95 deg for 30-45 mins.
5. Then drain.
6. Hot wash at 95 deg c. for 10 mins.
7. Cold wash.
8. Neutralize with Enzyme based Peroxide Killer ( 0.5 gpl) . Run at 45 deg c for 25 mins.
9. Now Ramie Fibre is ready for dyeing.
Ramie fibre is dyed using Reactive and Vat dyes.
As per requirement Ramie fibre is dyed using ME dyes at 60 deg c or HE dyes at 80 deg c. Where high fastness is required in that case Vat dyes are used.
After Treatment process for Ramie fibre is done as follows.
1. After dyeing give overflow rinse .
2. Hot wash at 95 deg c for 10 mins.
3. Neutralization for certain class of dyes ( bi-functional ).
4. Soaping with 1-2 gpl ( two soaping for dark shades ). 5. Softening with Cationic softener 2 % ( OWF ) at room temperature.
Bleaching of Ramie fibre
Ramie fibre is loaded in the fibre carrier. M;L ratio is 1;8.
Following chemicals are added into the m/c via side tank at room temperature.
1. De foamer – 0.3 gpl.
2. Wetting agent – 1 gpl.
3. Peroxide stabilizer – 0.75 gpl.
4. Hydrogen Peroxide ( 50 %)- 10 gpl.
Then raise temperature to 60 deg c at the rate 3 deg per min. run for 10 mins at 60 deg c. then add NaoH ( 50 % ) – 4gpl. Again run for 5 mins at 60 deg c then add
Optical Brightening Agent – 0.3 %
Raise temperature to 95 deg c at the rate of 3 deg per minute.. run for 60 mins at 95 deg c . then cool down to 80 deg c and drain.
Then hot wash at 80 deg c for 10 mins. Followed by cold wash at 50 deg c the softening is done by using Cationic softener – 2 % on weight of material. It is a special cationic softener Then unload. Hydroextract and dry it in dryer.
Uses of Ramie fibres-
The fiber is very fine like silk, and being naturally white in colour does not need.Chemically ramie is classified as a cellulose fiber, just as cotton, linen, and rayon. The leading global producers of ramie are China, Taiwan, Korea, the Philippines and Brazil. Ramie is often blended with cotton to make woven and knit fabrics that resemble fine linen to coarse canvas. Ramie is commonly used in clothing, tablecloths, napkins and handkerchiefs. It is often blended with cotton in knit sweaters. Outside the clothing industry, ramie is used in fish nets, canvas, upholstery fabrics, straw hats and fire hoses.
Despite its strength, ramie has had limited acceptance for textile use. The fibre’s extraction and cleaning are expensive, chiefly because of the several steps—involving scraping, pounding, heating, washing, or exposure to chemicals. Some or all are needed to separate the raw fibre from the adhesive gums or resins in which it is ensheathed. Spinning the fibre is made difficult by its brittle quality and low elasticity; and weaving is complicated by the hairy surface of the yarn, resulting from lack of cohesion between the fibres. The greater utilization of ramie depends upon the development of improved processing methods.
Ramie is used to make such products as industrial sewing thread, packing materials, fishing nets, and filter cloths. It is also made into fabrics for household furnishings (upholstery, canvas) and clothing, frequently in blends with other textile fibres (for instance when used in admixture with wool, shrinkage is reported to be greatly reduced when compared with pure wool.) Shorter fibres and waste are used in paper manufacture.
For the 2010 Prius, Toyota will begin using a new range of plant-derived ecological bioplastics made from the cellulose in wood or grass instead of petroleum. One of the two principal crops used is ramie.
Ramie is also used as an ornamental plant in eastern Asia.
Care Recommendations for Ramie Fabrics-
Care procedures prescribed on the care labels of ramie products vary. Items of 100 percent ramie should not require special care. Generally, they may be laundered or dry-cleaned depending on individual dyes, finishes and design applications. High temperatures will not harm the fiber itself, making washing in hot water and ironing at high settings possible; however, color retention, shrinkage control or properties of blended fibers may dictate lower temperatures. Recent laboratory testing done has led to the conclusion that the best performance results when gentler or more special handling is used in care. For example, fabrics retained the best color and shape with the most wrinkle-free appearance when they were dry-cleaned.
Machine washing in cold water on gentle cycle with line drying was better than machine washing in warm water with tumble drying on permanent press cool down cycle. Hand washing in cool water with flat drying is the most strongly recommended home care method for both knits and woven fabrics. The consumer who knows the strengths and limitations of the fiber can receive maximum service and enjoyment from ramie products.
When storing ramie or ramie blends, lay them flat. Ramie fibers are brittle and tend to break. Avoid folding the garment or pressing sharp creases in woven fabrics.
