Promising hemp fiber spinning technologies: LAROCHE сottonization equipment
We are pleased to announce the amazing results of the French company LAROCHE. For several months, Europe’s best technologists have been testing French technical hemp straw in order to extract the best fibres for use in the textile industry, without using chemicals and only mechanically.
The photo shows the first fabric samples obtained from hemp trust fibers (hemp straw after maceration in the field) using the technology of straw decoration, and then thinning and cottoning the fibers on the Laroche equipment. Spinning and weaving were made by our partners in Europe. This fabric is used basically for furniture.
Historically, hemp cultivation has been traditional for Russia, and in terms of agrotechnical conditions it provides certain advantages in crop rotations with mass commercial crops within the agriculture of the black and non-black soil zones. Hemp fiber belongs to the class of bast fibers together with flax fiber, and the problems of the technology of processing these fibers in spinning are similar.
The Laroche cottonization process chain is an extension of the straw or trust fibre production line, based on the technology of decorating, dedusting, cleaning and refinement of the fibres. The Laroche cottonizing line consists of the following technological modules: fibre slicing, cleaning, cottonization (fibre breakage into elementary fibres and reduction of linear density of the fibres), second cleaning and boiling.
Moreover, it is important to know that in order to obtain quality fibers from the raw materials, the proper maceration process and sufficient tensile strength of the original raw material are required. At the same time, the technological core of the cottonizing line is the EXEL cottonizing module with two double-drum cottonizators (only 4 fiber-retaining drums).
Testing of hemp straw are continuing to this day, with the aim of achieving even greater refinement of the fibres and fabrics respectively, in order to increase the percentage of hemp cottonin with cotton or wool blended yarn (50/50). All samples can be seen and touched at the Laroche Test Centre in France in Cours-la-Ville, where we are always happy to meet you.
Learn more information from our exclusive representative in Russia –
Galina Yelchaninova – Vice-President of APR (Association of Russian Textiles)
How to Spin Hemp Fiber
Spinning hemp fiber involves retting, decortification, softening, combing then spinning using wet or dry methods. Hemp fiber can be spun using any one of these three processes, cottonization, long fiber or tow processing.
Long Fiber Processing
• Hemp is harvested up to the mid flowering stage, which is then cut four to five feet from ground level, thus ensuring that both the seeds and the fibers are harvested. The plants are then left in the field to ret for about 10 to 20 day s. Retting is done either by water or dew.
• Water retting is a process where the stems are placed in water, more specifically, in ponds, tanks or streams for approximately 10 days . While dew retting involves laying the hemp parallel in rows so the morning dew falls on the hemp. During this time, the stems are turned at least twice to allow them to ‘ret’ or rot evenly.
• In either method of retting, pectin within the hemp, that binds the fibers to the stem’s core is being released, which causing the fibers to separate. The process is complete once the hemp stalks have become white , divides easily into fibers, separates from the core, and stalks are dry.
• At the end of the retting process, the fibers go through decortification. Some call this the grassing and scutching step. This is a drying process where the retted hemp is conditioned as well as freed from wood kernels by squeezing, breaking and scutching. More specifically, the stems are broken by passing them through fluted rollers.
• After this, the fibers are de-cored or “scutched” through a process of beating the stems with a beech stick. Alternatively, the stems may pass through rotary blades.
Softening and Combing
• After decortification, the hemp fibers are softened using a roller or softener . This causes the fibers to be suppler and softer.
• Then the softened hemp is combed. During this step, the long fibers are smoothed and “parallellized” with a hackling machine. While this is taking place, woody particles are being removed to produce a “continuous sliver” for the spinning step.
• At the end of the combing process, the spinning process begins. This is where the slivers are drawn and doubled , then pre-spun into roving yarns using dry or wet processes. The wet spinning process involves “ bobbin, drying and winding ” while dry spinning is done through the spinning frames used for spinning flax.
• Next, the yarns are bleached with hydrogen peroxide then boiled in caustic soda for refinement. With these methods of spinning, two types of yarn are produced, one that is short and the other is long. Wet spinning produces softer yards; however , dry spinning produces yarn that is cheaper but coarser.
Tow Processing and Cottonization
• At the scutching and hackling step, the shorter fibers are spun into a coarse yard using the wet or dry process. At this stage, they are refined and parallelalized using carding machines. This is the towing process.
• Cottonization is where long hemp yarns are turned into a texture similar to cotton. It involves removing substances such as lignin and pectin from the yarn. This step uses “ elementarization ,” similar to what is done when making cotton.How to Spin Hemp Fiber Spinning hemp fiber involves retting, decortification, softening, combing then spinning using wet or dry methods. Hemp fiber can be spun using any one of these three ]]>