The method of fibrous plant degumming

This invention relates to a method of fibrous plant degumming, especially to flax and hemp using physico-chemical processes, especially osmosis, occurring inside the plant stem in contact with water.

There are many commonly known methods for plant fiber degumming that allow for separation of fiber from the woody part, and removal of non-cellulosic components such as pectin, hemicellulose, lignin, waxes and fats. A traditionally used method for degumming is dew retting of fibrous plants in the field. The principle of the process is micro organisms, mainly fungi, which penetrate the swathed stems and decompose pectin, commonly referred to as plant glue, with enzymes and thus conduct the process. Such process is difficult to control and, depending on the atmospheric conditions (air temperature, humidity, rain), the fiber of different quality is obtained. Another method of fibrous plant degumming is water retting in special tanks or ponds. In this case the biochemical phenomena occurring as result of bacteria action (fermentation) cause the separation of the woody part of stem from the fiber. This process can be conducted in aerobic and anaerobic conditions.

To create optimal conditions for "retting" microorganisms growth and to speed up the process the stimulators of degumming were used such as nitrogen (urea) media or leavens: retting liquor recycling, "double retting" and inoculation with retted matted straw. All these solutions aimed at faster and simultaneous degumming of fiber from the woody part of stem and decomposition of pectin in the fiber itself which resulted in shortening of degumming time and improvement of fiber quality, mainly by increasing fiber divisibility and thinning the fiber strand.

In patent description GB 2 186 002 (published on 1987-08-05) the non-retted or under-retted flax straw and green fiber treated with a metal chelating agent in alkaline solution to weaken the hemicellulose and pectin bonds and to enable the fiber to be readily separated from the straw was presented. In patent description GB 2 186 002 (published on 1987-08-05) the process applied also to fabric containing under-retted fibers was presented.. Preferred chelating agents are the sodium salt of ethylene diamine tetra-acetic acid (EDTA), the tetra sodium salt of this EDTA and penta sodium salt of diethyl triamine penton acetic acid. Treatment temperature is 35-50 degrees C for straw and under-retted flax, and ambient temperature for grey fabric . International P atent Classification DOlC.

In patent description EP 220913 (published on 1987-05-06) the enzymatic retting of flax or other plants was presented. In a method for batchwise enzymatic retting of flax or other plants with regard to fiber release, the cut flax etc. is treated with an SPS-ase preparation produced by a strain of the genus Aspergillus, preferably Aspergillus japonicus or Aspergillus aculeatus in an aq. medium until the retting is completed. If desired, the retted flax fiber is decolorized by exposure to moderate bleaching. The method can be completed in a few hr and gives a better yield and better strength retted fibers with a lighter color. The method causes less pollution with retted fibers of reproducible quality giving thinner fibers with a higher average degree of polymerization of the cellulose. Preferably the SPS- ase activity in the aq. medium is 90-250 U/l. The pH is adjusted to preferably 4.5-5.5, and the temperature to 15-45 deg.

In patent description CNl 342789 (published on 2002-04-03) a degumming process for oil seed flax features has been described in which under the ambient condition of 12-32 deg. C and more than 70% of relative humidity, the oil seed flax stems are spread on grassland or oil seed flax field by 1-2.5 cm of thickness for 7-14 days and turned over every 3 days so to complete the process. Its advantages are convenient operation, low cost, no environmental pollution and no damage to flax fibers.

In patent description KR2001088933 (published on 2001-09-29) a method for degumming decorticated plant bast fiber has been presented. The methods for degumming bast fiber a tenacious plant are described. According to the methods, the bast fiber is effectively degummed by a mixture of an aerobic bacterial culture and an anaerobic bacterial culture at a temperature of 38 DEG C SIMILAR 40 DEG c and a pH OF 6.0 SIMILAR 7.0. hi patent description US4617383 (published on 1986-10-14) a method for degumming and bleaching decorticated plant bast fiber has been presented. This is a method for degumming decorticated plant bast fiber, such as ramie, flax, or hemp bast fiber, to remove

pectin-containing material and coloring gums therefrom. The decorticated plant bast fiber is desirably washed with a washing solution containing a surface active agent to penetrate the plant bast fiber and remove water soluble material and other debris therefrom. The washed plant bast fiber is then rinsed. The washed and rinsed plant bast fiber is treated with an aqueous acidic treatment solution of fungal pectinase for a period of time of between 10 and 30 minutes to remove the pectin from the plant fiber. The acidic treatment solution is maintained at an elevated temperature in the range of between 60 DEG C. and 70 DEG C. and has a pH between about 2.0 and 3.5. Thereafter, the plant bast fiber with the pectin removed therefrom, is removed from the acidic treatment solution and a sufficient amount of NaOH is added thereto to increase the pH of the treatment solution to about 11.0. The plant bast fiber with the pectin removed therefrom is then further treated in the basic solution for a period of time between about 15 to 60 minutes to remove the coloring gum adhering to the plant bast fiber. The plant bast fiber with both the pectin and the coloring gum removed therefrom is then rinsed to remove the treating solution therefrom.

In patent description WO 2003006722 (published on 2003-01-23) a method for sepg. decorticated bast skin into individual fibers has been presented, comprises maintaining decorticated bast skin in a closed container in the presence of at least one enzymic and/or chem. retting agent for a period sufficient for at least a portion of the fiber bundles to sep. into individual fibers.

In patent description EP 0 221 811 (published on 1985-05-13) process for biochemical retting of plants containing bast fibers has been presented. An enzymatic retting of flax or hemp which employs the enzyme SPS-ase is claimed. International Patent Classification DOlC. In patent description WO8702390 (published on 1987-04-23) a biochemical retting of fibrous bast plants has been presented. A process for the biochemical retting of fibrous bast plants to achieve degradation of cements aggregating the fibers and separation of the fibers from the bunch to enable their use in the (para) textile industry comprises treating the plants with SPS-ase enzymes. SPS-ase is a wide spectrum polyactive enzyme acting on polysaccharides. The obtained fibers are also claimed. The method is used for retting plants such as hemp, flax, ramie, jute and kenaf and produce fibers for spinning or cord production. The process is reproducible and does not adversely affect the fibers. The fibrous plants are treated with a mixture of SPS-ase and beta-glucanase and preferably also pectinase (EC-3.2.1.15) in a preferred process. Treatment is effected by impregnation and then maceration of the straws or tows in an aq. medium containing the enzymes.

Maceration is effected for 1-48 (3-36) hr at 20-70 (40-60) deg and at pH 3-7 (4-6). In patent description USP 4 481 355 (published on 1984-11-06) a method for degumming decorticated plant bast fibers to remove pectin-containing material is claimed. In patent descriptions USP 4 568 739 (published on 1986-02-04) and USP 4 617 383 (published on 1986-10-14) a method for degumming decorticated plant bast fiber has been presented. A method of degumming decorticated plant bast fiber to remove pectin- containing material from it comprises washing and rinsing the bast fiber and treating it with an aqueous acidic treatment solution of fungal pectinase. In patent description EP 1 082 472 (published on 1999-02-26) a plant material processing system has been presented. A system for processing plant material is provided which separates plant fibers from the woody portions of the material to produce a commercially desirable length of fiber and to grind the shorter woody portions that have been separated from the longer fibers to a desirable size which has found use in certain commercial applications. The current system is well suited to process the tough fibers of the North American strain of flax straw, and will also find utility in processing other bast fibers, such as jute, hemp, ramie, and kenaf.

In patent submission CN1594719 (published on 2005-03-16) a peeling and degumming process for hemp plants has been presented. The invention refers to textile industry field. The character lies in: the invention uses ambary, Calcutta hemp or sun hemp bast fiber as material, through biological deglue, then adds in compound enzyme to modify them, the deglued and modified fibers is decreased in fiber crystallinity, initial modulus and lignin content, the fiber softness, crack intensity and separation rate are improved prominently, the invention upgrades the textile performance of the fiber. The invention solves the bottleneck problem of coarse and fine process of ambary, Calcutta hemp and sun hemp, realizes clean production, and has no contamination to environment. The invention has a low synthesis cost, the economic efficiency and environment efficiency are significant. In patent description CN1400338 (published on 2003-03-05) a method for cleaning and degumming steamed hemp has been presented. The invention adopts steam-knocking process to make hemicellulose and lignin in the hemp partially degrade, then uses the micro-biological zymogenic and zymolytic coupling method to make the steam-knocked hemp undergo further degumming treatment, finally uses hydrogen peroxide to bleach hemp, the prepared refined help is white and loose, and its quantity is good. The steam- knocking treatment can degrade 80% of hemicellulose and pectin firstly, it not only can provide required nutrients for micro-biological fermentation, but also can break natural structure of hemp, so that it is favorable for zymolysis of pectin and removing it so as to

attain the goal of degumming hemp.

In patent description CNl 125788 (published on 1996-07-03) a biological degumming technology for hemp bast has been presented. The technology includes such steps as clustering, cutting into 750-850 mm in length, retting at 21-25 deg.C for 70-74 hr, washing with water, drying, beating, and clustering again, and features low environmental pollution, high yield rate and low cost. Obtained hemp fibers with 650-750 mm in length has increased spinnability and may be used to spin high-count and -quality bast fabrics. In patent description CNl 089669 (published on 1994-07-20) an enzymolysis method for degumming of hemp has been presented. In this invention, autogenetic bacteria of hemp are cultivated under anaerobic condition when their integrated activity is raised to 100-200 mu/ml, artificially cultivated supplementary bacteria are added, thus a complex decomposition enzyme for pectin is formed. The pH and temp, of degumming are controlled, so the growth and reproduction of bacteria is rapid, the activity is maintained at 200-250 mu/ml, and time of degumming is also controlled, so hemp is degummed just in time and in degree. Then it is washed with water to a neutral condition and dried. The degummed hemp produced by the degumming technique of this invention may be woven for 5-36NM hemp yarn of various grades, the productivity of hemp is raised to 33 percent, the degumming speed is rapid, and the product quality is stable. In patent description CN1058624 (published on 1992-02-12) a method and apparatus for comprehensive treatment of waste from biological degumming of ramie has been presented. This invention relates to a complete set technology of combined bacterio- chemical degumming process for ramie with equipment thereof. It features that the refined waste gas generated in biological degumming of ramie, waste water after flushing machine, oiled waste liquid, condensed water of baker, partial refined water liquid and fermentation tail-gas treatment are used for the immersion of bacterially degummed ramie, beating ramie, refining, oiling, and filtering the soot of boiler, so realizing comprehensive treatment of waste water. Its settling tank is a plane-rectangular diagonal flow type. This invention has such advantages as low investment, low running expense and good treatment effect. The quality of treated water conforms to class-one national standard. In patent description EP 0 907 780 (published on 1996-06-27) a fiber product, method and apparatus for manufacturing a fiber product has been presented. The invention concerns a product obtained from flax or similar bast fiber which contains actual stalk fibers and shives originating in the same plant. Both fibers and shives are incorporated in the product by appropriately crushing the stalk. The product may be a pressed-to-shape structural element, or a porous product such as an insulating material or a product for use in

cultivation. The method of production is also claimed.

Inspite above-mentioned research devoted to methods of fibrous plants degumming, especially flax and hemp by physico-chemical phenomena, there is a constant need to create more efficient solutions allowing for obtaining higher efficiency of the process and keep the process free of by-products dangerous to environment, poisonous to living creatures and having bad effect on fiber quality (softness, smell, strength). A classical process of retting is run by the fermentation process conducted by microorganisms. The by-products in this case are mainly volatile fatty acids such as: acetic, butyric, propionic, formic and valeric, that contribute to the pH reduction and increase of post-retting liquor acidity. Additionally, the liquor produces bad odor of decomposing impurities. In the process of osmotic degumming the process that extracts the fiber from the stem is leaching of mineral and organic substances, thus no micro flora is being developed.

The goal of the present invention is to render the method of degumming of fibrous plants, especially flax and hemp. The process is based on physico-chemical phenomena, especially osmosis, occurring inside the fibrous plants in contact with pure water, using no chemicals, enzymes nor bacterial and fungal inoculations. Using fibrous plant degumming based on natural physico-chemical phenomena allows for obtaining sewage characterised by a low load of easy-to-neutralize pollutants. The whole process cycle requires considerable amounts of water. Therefore, application of filters allows for full recycling of water and thus improves the economics of the process.

The realisation of such a defined goal and resolution of the problems described in the state of the art regarding the degumming of fibrous plants, especially flax and hemp using physico-chemical processes, especially osmosis were achieved in the present invention. Furthermore by using the osmotic degumming of fibrous plants we may achieve the objective estimation method both quantitative and qualitative of the fibre in the stock. It is very important aspect in the development of the new fibrous plants cultivations.

The subject of the present invention is the method of a fibrous plant degumming in which the stems are placed in a container and flooded with water, characterised in that, the ratio is from 70:1 to 10:1 in relation to stem weight and the extraction of fibers is carried out by natural physical laws, namely water diffusion and/or osmosis and/or osmotic

pressure, where the process includes three phases: a) phase 1, in which submerged in water stems are soaking the water and swelling and are leading up to the moment when water soluble mineral salts, pectin A, retting bacteria and pigments are being leached out from the stems causing the liquor to turn brown (with different intensity) and gas bubbles are appearing; b) in phase 2 the osmotic pressure is generated inside the stem, the water particles diffuse through the semi-permeable membrane until the concentration of water particles inside the stem is lower than outside, so the concentration of water particles inside the stem grows; c) in phase 3 the osmotic pressure inside the stem causes the stem fracture.

Preferentially, the fibrous plants are exposed to water in constant water flow. Preferentially, the fibrous plants are exposed to water using periodical exchange of water.

Preferentially, the water soluble substances are being leached out throughout the whole process, which causes water coloration, opacity and decrease of its pH reaction below 7.

Preferentially, the temperature in the tank varies from 7 ⁰ C to 6O ⁰ C .

Preferentially, the leaching process is conducted in time dependent from decrease of pH to the terminal value pH 5.

Preferentially, the coloration and opacity occurs.

Preferentially, the the stems are draining off from the water solution in time dependent from decrease of pH to the terminal value pH 5.

Preferentially, the stems are flooded again with water within the range of temperature 7- 6O ⁰ C.

Preferentially, the exchange of water, leaching process and water removal is cyclically repeated in time dependent on the decrease of pH to the terminal value pH 5.

Preferentially, the constant water flow is applied in amount depending on the decrease of pH to the terminal value pH 5. Preferentially, the temperature of supplied water is within the range of 7-6O ⁰ C.

Preferentially, the degree of degumming is determined organoleptically by the ease of fiber separation from wood.

Preferentially, when the fiber in the straw has been separated from wood the process is then considered terminated; after that the water is draining off from the straw, pressed out and the measures are undertaken to prevent the development of retting bacteria on the surface of the raw material; then the straw is dried, broken and fiber is separated.

Preferentially, the flax stems are subject to degumming.

Preferentially, the hemp stems are subject to degumming.

Preferentially, the degumming is carried out in solution of pH 8.0-5.0. Preferentially, the degumming is carried out in closed water cycle using membrane filters.

Preferentially, the method is used for evaluation of fiber content in the raw material. Preferentially, the whole plant and/or the middle part of plant is subject to degumming.

The examples of using the invention defined above are listed below.

Example I

Hemp stems are placed in a tank and flooded with water of 15 ⁰ C in amount ten-fold exceeding the amount of stems. After some time, depending on liquor reaction reduction to pH 5, the water is removed and replaced with a fresh one, having 15 ⁰ C, in amount ten-fold exceeding the amount of stems. The degree of retting should be deteπnined organoleptically and monitored throughout the whole process. When the straw is degummed, the process is considered to be completed. Next, the water is removed, straw is pressed to remove more water, the measures are undertaken to prevent the development of retting bacteria on the surface of the raw material, dried, broken and fiber is extracted.

Example II

Flax stems are placed in a tank and flooded with water of 15 ⁰ C in amount ten-fold exceeding the amount of stems. The leaching process is carried out in continuously flowing water. The amount of water depends on the water reaction reduction to a threshold value of pH 5. The degree of retting should be determined organoleptically and monitored throughout the whole process. When the straw is degummed, the process is considered completed. Next, the water is removed, straw is pressed to remove more water, the measures are undertaken to prevent the development of retting bacteria on the surface of the raw material, dried, broken and fiber is extracted.