Stock material or miscellaneous articles – Coated or structually defined flake – particle – cell – strand,... – Rod – strand – filament or fiber
Patent
1990-12-14
1993-08-03
Ryan, Patrick J.
Stock material or miscellaneous articles
Coated or structually defined flake, particle, cell, strand,...
Rod, strand, filament or fiber
428381, 428383, 428389, 428390, 428393, 428402, 162 70, 162 71, 162 72, 162 79, 162158, D02G 300, B32B 1302, D21C 300
Patent
active
052327795
DESCRIPTION:
BRIEF SUMMARY
The invention relates to reinforcement fibers and/or process fibers based on plant fibers, method for their production, and their use.
It is known that asbestos fibers are frequently mixed to molded parts. It was found recently that asbestos is by no means harmless from the point of view of health. In spite of this disadvantage, these fibers continue to be used to a large extent because in many fields of application they have great advantages and genuine alternatives are not on the market at this time.
The same applies for glass fibers. Artificial fibers also are not harmless since at increased temperatures breakdown reactions can take place with the formation of toxic vapors.
Attempts have also been made to find a substitute material for asbestos based on plant fibers. DE-OS 30 08 204 describes a method for the production of reinforcing fibers in which, with respect to the capillaries, the plant fibers are initially opened and subsequently the plant fibers treated in this way are impregnated with a slurry of lime and water and, after an intermediate drying process, with a solution of sodium silicate containing formaldehyde. These treatment steps can also be carried out in reverse sequence, this method, however, has also not led to the desired success.
The invention is therefore based on the task of making available reinforcing and process fibers which have the advantageous properties of the asbestos fibers without having their detelerious health disadvantages.
The task is solved by reinforcing and process fibers based on plant fibers obtainable through the following method.
The method for the production of the reinforcing and process fibers according to the invention is characterized in that: removed from the fiber-containing parts of the fiber plants, treated, if desired, with an aqueous solution of at least one metal compound, selected from metal oxides, metal hydroxides, metal carbonates, metal sulfates, metal thiosulfates, metal sulfites, metal silicates or metal phosphates, that they are subsequently washed and treated with an inorganic or organic binding agent or that the non-washed fibers are neutralized with a mineral acid, or an oxidizing agent, or 350.degree. C. with controlled addition of air so that carbonization of the fibers takes place.
For the production of the reinforcement and process fibers, fibers of all fiber plants are suitable. Preferably bast fibers are used such as the stem fibers of flax, hemp, jute, nettle plants, the leaf fibers of the agave, the seed hair of, for example, cotton, and coconut shell fibers. Also, fibers obtainable from grasses, in particular from elephant grass which has a fiber component of approximately 50%, are usable.
The plant fibers in cut or uncut form must first be freed of wood components and other undesired plant components. This takes place by known and conventional methods, for example through roasting and decortication of green flax.
According to a preferred embodiment, the removal of the wood components takes place by breaking down the plant fibers with ultrasonic treatment in an aqueous medium. The length of the ultrasonic wave is not critical. It is chosen, depending on the apparatus, preferably so that optimum sound intensity is achieved and ultrasonic cavitation occurs.
A mixture of water with at least one polar organic solvent is preferably used as the aqueous medium. As organic solvent there is preferably used a C.sub.1 - to C.sub.4 -mono- or dialcohol, a C.sub.1 - to C.sub.4 -ketone, an ether miscible with water, or a mixture thereof. Especially preferred are methanol, ethanol, and acetone. The volume ratio of water to organic solvent lies preferably in the range from 5:1 to 1:5, particularly 3:1 to 1:3.
The ultrasonic method is a particularly fast simple and gentle method for removing the wood components and other undesired components of the raw plant fibers. The plant fibers obtained in this manner are not damaged mechanically and they possess the tear resistance of the original fiber. Since the other undesired plant components, in particu
REFERENCES:
patent: 4647505 (1987-03-01), Blackie et al.
Ecco Gleittechnik GmbH
Ryan Patrick J.
Weisberger Richard P.
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