Flax is an ancient source of natural fibers which had been used for thousands of years. It is one of the most important economic crops in China, behind cotton fiber in textile industry.

Flax is the epidermal layer fiber of plants, the structure of which is similar to human skin. It has a natural function of defending the body and regulating temperature. The length and thickness of flax fiber is close to cotton fiber, while the degree of cellulose macromolecular orientation in its cell wall is higher than cotton fiber, also with a larger crystallinity. Therefore, flax fiber has a higher strength than cotton fiber, reaching a elongation of 6.5 gram per denier, as the half of cotton fiber 3.5%, but more brittle. The surface of flax fiber is smooth, thus easy to absorb moisture and help return water to air rapidly. The fiber is straight and hard to distortion with a high strength and low extensibility. Flax garments can absorb sweat better than other material and its water absorption velocity is several times faster than cotton. The capillary phenomenon appears when it contacts skin, acting as an extension of skin. These natural breathability, hygroscopicity and flash drying make it a freely-breathing textile fiber, which is known as “natural air conditioner” “fiber queen”. USDA(United States Department of Agriculture) designated flax staple as a 100% BioPreferred® product.

What’s more, flax fiber is also preferred by consumers for its natural healthcare functions of anti-microbial and ultraviolet radiation absorbing. Flax fiber has a good property as well as distinctive characteristics and becomes an important source of traditional superior textile products in the United States and European nations.

China is a textile country and holds 12% of the world flax textile processing quantity, leading the production and trade of ramie and linen. With the increasing demand of flax fabrics from home and abroad as well as limitation of resource utilization techniques, the flax textile industry is restricted from source shortage, therefore importing huge quantity of flax raw material every year. As a result, the comprehensive utilization of flax leftovers and resource utilization maximizing become the focus concerned day by day. With the decreasing of cotton planting area in China and rise in price, it is particularly eager to develop utilization of non-cotton natural fiber. Meanwhile, continuous development and application of multi- fiber fabrics help a lot to apply fiber source and differential fiber.

After the first process of retting and scotching, long ramie fiber can be wet span into hair cords, and part of leftovers fluffed and blended with cotton and other fibers into rather cheap products. The loss outweighs the gain. The deserted part leads to waste of sources.

The leftover of flax is a mixture of fibers, ramie leather and hemps without process of degumming and purification. Developing it into hemp soft cloth by bioprocess technology can sharply enhance the utilizing rate of flax source and alleviate the shortage of flax textile industry source. Hemp soft cloth can be blended with various superior fibers (such as colored cotton, wool, cashmere, real silk, etc.) and enhance the level of products and added value. Its wide utilization in garments and bedding broadens application areas of flax products.

Development status and trend at home and abroad-- about practice and theory on bioprocess technology of flax leftovers.

China has the largest ramie and flax planting area, covering more than 28% flax planting area in the world. However, with the increasing flax products exports, domestic demand rises, especially flax fiber sources. Making the most of flax source and developing flax leftovers have become a focus of the industry. Recently, traditional flax degumming process lags behind and causes severe pollution and low fiber quality. Therefore, developing degumming techniques and equipment, reducing environmental pollution, as well as enhancing yield and product quality, have becoming a trend in flax textile industry.

The researches about flax bioprocessing techniques in China are limited and ongoing, still taking time towards scale-up production. In the 11th five-year plan, the comprehensive utilization of non-cotton fiber and supporting natural fibers diversity were raised clearly. For one thing, it can make up the shortage of cotton sources; for another, it may use differential fiber textile techniques to enhance the wearability of fabrics. The bioprocessing and fining process are just fitting the developing direction. And the flax planting area in China holds over 28% of the world planting area, as much as more than 15% of domestic cotton output. If the utilization rate of flax fiber reaches above 90%, then the shortage of cotton sources can be effectively relieved.

The utilization of flax fiber takes the leading position abroad, such as Italy, England, France and Belgium, where flax products are superior products. But the utilization of leftovers has been ignored, especially in 1990s, when they sell flax leftovers to developing countries after simple fluffing process. China is among main import countries as well.

According to recent researches, our exquisite bioprocessing techniques of flax leftovers take a leading position at home and abroad.

The symbioses of natural fibers are protective layer during plant growth. They are both important protection and obstacle in textile processing. In traditional techniques, people use high-alkalinity chemicals such as NaOH or plenty auxiliary chemicals to wipe out symbioses. But this will destroy many advantages of cellulose and greatly reduce its good processing and physical properties. In addition, the high energy consumption and emission will lead to environmental pollution and endanger human living environment.

On the contrary, biotechnology stems from the nature. Environmental-friendly techniques can give flax fiber great quality and spinnability to the most degree and make it hemp soft cloth or blended with many other new superior fibers, such as wool, cashmere, silk and colored cotton, effectively enhancing the added value of products.

Flax leftovers bioprocessing techniques can help achieve “three low” “two high”.

Three low:

1.Low consumption. Low liquor ratio (<1:8), save over 50% water, short-process, save over 50% electricity; low-temperature, ≤55℃, yarding at normal temperature, save 80% steam.

2.Low pressure. Processing at normal temperature and pressure, production and fiber safety can be guaranteed, low rejection rate, low weight-loss ratio.

3.Low emission. Basicly no waste gas or water emission, using water <1ton per 100Kg flax fiber processing, which is 1/4 as before, work liquid PH value 7-8, add a set of water-processing equipment, recycle waste water over 90%, basicly zero-emission. Sediment are organics, can be recycled into organic fertilizer.

Water-processing flow:

recycle—neutralize—subside—filter—reuse collect water—solid organic fertilizer Achieve green, low-carbon, environmental production line.

Two high:

1.High quality. Guarantee the fiber strength, not damaged; disintegration degree highly improved; weavability techniques improved; dyeing and finishing process simplified.

2.High efficiency. Yield ratio 90%, spinning yield ratio 85%, weight-loss ratio<10%; low temperature and normal pressure, short-process, time-saving and effective.

Experimental process flow (by tube gaze dyeing equipment):

1.Enzymes scouring (50-55℃)—hot washing and extracting—softening—drying—opening—packing Characteristics: low amounts of enzymes, long time, low comprehensive cost.

(one bath refining enzymes—oxygen bleaching)—hot washing and extracting—softening—drying—opening—packing Characteristics: refining by hydrogen peroxide, one bath scouring and oxygen bleaching, save time and energy.Traditional fiber processing and bioprocessing techniques measurement comparison

To sum up, after bioprocessing, flax leftovers become high-quality flax velvet. This is practicable and reliable and can be applied to various cotton spinning to obtain economic and social benefits and meet the demands of global market.

The application and prospect of flax velvet The physical norms of flax velvet are close to cotton fiber. It has a wide range of application and a good property. This kind of flax fiber, blended with superior fibers, can be used to produce functional fabrics of good wearability.

Spandex can be added to make elastane yarns and fabrics; static wire can be added to make antistatic uniforms in special industries; fire-proofing and antiflaming fabrics are available as well. Combing fall object can be blended with rotor-spun yarns into coarse yarn for denim. This technique takes full advantage of flax source and greatly expands categories of high-end textile.

The techniques we are using are environmental friendly, resource-saving, intensive and high efficient with great social and economic benefits, leading the textile industry.

1.Technical route: preparing flax leftovers—bioprocessing—cotton type fiber fining—finished product Key technique: enzymes bioprocessing technique, fiber fining technique

2.Major process flow Grey fibers: enzymes scouring—hot washing and extracting—softening—drying—opening, fining—packing Bleached fibers: (enzymes refining—one bath oxygen bleaching)—hot washing and extracting—softening—opening and fining—packing Technical and quality indexes (According to GB/T18888-2002)

Note: 1. The standard is close to quality of cotton 229.
2. Improved in pilot-scale study, disintegration degree can be over 2000.