Common uses of flax
Flaxseed has always been an extremely versatile plant used for both its unique oil and fibre qualities, but research is opening many new doors in areas of new bio-based industrial uses and improved methods for textile production.
There is a growing trend back to natural fibres for industrial and non-traditional end-uses. For example, in Western Europe companies are now using flax, hemp, sisal and jute fibres to replace the glass fibres (i.e., fiberglass) used in many plastic composites, particularly for those used in the automotive sector. This trend is just beginning to spread to North America and East Asia;
There is a growing trend back to natural fibres for clothing. The latest class of French and German drafting and spinning equipment can now produce linen yarn that is even enough to be knitted. This new development permits the production of linen knitwear that is cooler and more comfortable than cotton.
Uses for flaxseed straw vary depending on the quality of the straw, and in regard to fibre production, largely depends upon the degree of retting (straw breakdown). Retting is a biological process making it easier to separate the fibre from the non fibre shive component of the straw. There are several methods to ret flax and several partial or total alternatives to retting. These include enzyme treatments, steam explosion (flash hydrolysis) and ultra sound, chemical “cooking”, and/or grinding and screening.
Paper, Plastic and Insulation
On the lower end of the value-added scale, flax may be used for specialty papers or geotextiles (ground-cover materials). As the straw is further cleaned and processed, more value added opportunities arise including plastic composites, packing materials and insulation. The most highly processed flax fibre is used in absorbency products and textiles.
Canada can produce good quality straw with fibre suitable for higher end uses like textiles, reinforcement for plastic composites, building insulation, nonwovens and other uses if the straw is retted. It is possible to ret straw in Canada several different ways including field retting, when the straw is placed in contact with the soil. Several agronomic management techniques have been identified that can substantially increase straw yields and fibre content.
Flax fibre was traditionally used for specialty pulp and paper, linen garments and other textile applications. The traditional linen markets still exist and markets for flax fibre have expanded into nonwovens, reinforcement for plastic composites, building insulation and others.
Flax shives are the byproduct of fibre extraction. Shive content depends upon the bast fibre content of the straw and is normally in the 65-85% range. Flax shive markets include filler for plastic composites, loose fill insulation, absorbency products, pet and livestock bedding and others.
Flaxseed oil is used extensively for the manufacture of flooring products (linoleum) as well as paints and coatings. Linoleum is a renewable floor covering. Due to its many technical and environmental performance advantages, linoleum is making a comeback in floor covering markets after being displaced several decades ago by less expensive vinyl flooring. Building design recommendations such as the LEED program are supporting an increasing focus upon linoleum. The high levels of the omega-3 fatty acid, alpha-linolenic acid, in flaxseed oil provides the basis for its unique chemistry and drying oil functionality.
Flaxseed oil is used as a plasticizer in polyvinyl chloride (PVC) and other vinyl resins. Epoxidized linseed (flax) oil (ELO) is produced commercially and is used as a plasticizer in reactive diluents. It is also used as a toughening agent for commercial epoxy resin and as a binder for cationic UV-coatings and inks.
PVC resin is widely used globally for a variety of end-uses such as flexible packaging, bags, medical products, toys, tubes, flooring, etc. For all the flexible, as well as semi-rigid, PVC applications, the rigid resin needs to be plasticized so it can be extruded into useful articles with required strength, toughness, flexibility and other properties.
Longer term significant opportunity areas for industrial use of flaxseed oil includes reactive diluents; reactive coalescents; water-based and powder coatings; and as replacements for phthalate plasticizers in PVC.