FR2748497A1 - PROCESS FOR THE MANUFACTURE OF SHAPE BODIES FROM FIBROUS AND / OR NATURAL FIBER PLANTS AND CORRESPONDING SHAPE BODIES - Google Patents

Abstract

The invention relates to a method of manufacturing shaped bodies made of fibrous plant elements and / or natural fibers, in which these fibrous plant elements and / or natural fibers are impregnated, dried at will, treated with a binder and the mixture is then formed. According to the invention, the impregnating agent used is a finishing agent for coatings in the building industry. It may contain at least one aqueous or organic solution or dispersion of a polymer, and the binder may comprise at least one polymer used in the building materials art for binding solid particles together and may contain at least one solution or an aqueous or organic dispersion of a polymer. The fibrous plant elements preferably comprise finely chopped straw. The invention also relates to corresponding shaped bodies.

Description

PROCESS FOR MANUFACTURING SHAPE BODIES FROM FIBROUS PLANT ELEMENTS

AND / OR NATURAL FIBERS AND BODY

OF CORRESPONDING SHAPE

  The present invention relates to a process for manufacturing shaped bodies from fibrous plant elements or from natural fibers, as well as shaped bodies

achievable in this way.

  It is known that a combination of different materials makes it possible to obtain materials whose properties are additively composed of those of the individual components. For example, the mechanical resistance and the stability of materials, in particular artificial materials, can be increased by mixing or introducing fibers. It is preferably synthetic fibers, asbestos or glass fibers which have been used hitherto for this purpose. However, it has recently become apparent that such fibers are clearly not

without health risks.

  The search for variants of materials has already made it possible to determine that vegetable fibers, among others, can be used advantageously, as reinforcing fibers. Some particular plants, such as flax, hemp or jute, produce sturdy fibers, resistant and yet elastic enough to be usable by spinning techniques. Due to these special properties, such vegetable fibers can even be processed to form composite materials in which they can be used not only as additives, but also as main components. Examples of such composite materials include nonwoven materials which are used as insulating materials or as flooring in the construction of buildings. However, only vegetable fibers which allow the production of nonwovens of fibers are suitable for these productions. Such fiber nonwovens represent a loose composite of the fibers used, which generally remain assembled together only under the effect of the inherent adhesion of the fibers. Many fibrous plant elements and natural fibers can be

  transformed into form bodies by this process.

  It is the aim of the present invention to produce shaped bodies, from fibrous plant elements and natural fibers, in such a way that the resulting composite materials have properties which

  meet different needs, for example mechanical strength, durability, water resistance and rapid biodegradability.

  This object is achieved by a process in which fibrous plant elements and / or natural fibers are impregnated, at will dried, treated with a binder and the mixture is then formed, the impregnating agent used being a coating agent for the plaster industry

building.

  The suitable primers for plasters in the building industry, in accordance with the invention, are usually used in the building industry for plasters intended to remediate superficial brittle and absorbent mineral basements, to consolidate coatings. old pulverulent remains, for example glue-paint surfaces cleaned by washing, or to reduce the absorption capacity of porous basements, for example plaster, raw bricks, aerated concrete, natural or artificial stone . We know of many agents that have been designed for this purpose and

  which have the advantageous properties suitable for the invention.

  Particularly suitable elements are polymers of natural or synthetic origin, the former also including polymers of natural origin which are then modified, for example chemically. In the context of the present invention, the term polymer denotes both homopolymers and copolymers, or terpolymers. An important condition for the polymers to be able to serve as impregnating agents according to the invention is their ability to penetrate the material to be treated. This penetration must be sufficient and it can possibly

  be influenced by adding common adjuvants, such as wetting agents.

  Polymers in the form of a solution and / or dispersion are preferred within the framework of the present invention. Such polymers in the form of a solution or of a dispersion comprise homopolymers or copolymers which can be produced by polymerization of numerous monomers and comonomers. It is therefore understood that the monomers listed below by way of example can also be used as comonomers for the manufacture of suitable polymers. Examples of such monomers that may be mentioned are alkyl esters C2 to C40 of acrylic acid or alkyl esters C1 to C40 of methacrylic acid such as methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, n-butyl methacrylate, isobutyl acrylate, isobutyl methacrylate, t-butyl acrylate, t-butyl methacrylate, pentyl acrylate, pentyl methacrylate, n-hexyl acrylate, n-hexyl methacrylate, n-hexyl acrylate n-heptyl, n-heptyl methacrylate, n-octyl acrylate, n-octyl methacrylate, ethyl-2-hexyl acrylate, ethyl-2-hexyl methacrylate, decyl acrylate , decyl methacrylate, lauryl acrylate, lauryl methacrylate, palmityl acrylate, palmityl methacrylate, stearyl acrylate, methacrylate stearyl, Hydrenol acrylate, Hydrenol methacrylate, behenyl acrylate, behenyl methacrylate, polyisobutene acrylate, polyisobutene methacrylate, phenoxyethyl acrylate, phenoxyethyl methacrylate, l phenyl acrylate and methacrylate

phenyl.

  Other monomers are chosen from the group consisting of vinyl aromatic compounds such as styrene, t-olefins such as butadiene, vinyl lactams such as N-vinylpyrrolidone, esters

  vinyl, acrylonitriles, acrylamides, acrylic acid or methacrylic acid.

  The preferred impregnating agents according to the invention

  include polyacrylates, polymethacrylates, acrylate-methacrylate and styrene-butadiene copolymers.

  The solutions and dispersions of polymers described above can be carried out according to a process known to those skilled in the art, for example solution, suspension or emulsion polymerization. The adjuvants used for this purpose, for example initiators of

  polymerization, redox or redox catalysts, regulators, emulsifiers and / or colloidal protection products are known to those skilled in the art.

  The solids content of the impregnating agent, as long as it is present in solution or in dispersion, is usually 0.5 to 50% by weight, preferably 0.5 to 15%, based on the agent's total weight. To treat fibrous plant elements or glass fibers, the impregnating agent according to the invention is used in the form of an aqueous or organic solution or dispersion. The material to be treated can for example be immersed in the solution or dispersion or be sprayed therewith. The impregnation is preferably carried out at room temperature, and the reaction time must be sufficient for the maximum penetration depth of the agent to be reached. It is possible at will to remove

  the solution or dispersing agent in a next drying step. This process can be controlled by choosing an appropriate drying temperature.

  The mixture thus prepared is preferably in the form of loose particles, the dimensions of which depend mainly on the particle sizes of the fibrous plant elements and / or of the natural fibers used as original materials. This mixture, that is to say

  the fibrous plant elements and / or the impregnated natural fibers is then mixed with an appropriate binder.

  Suitable binders according to the invention include for example usual polymers used to serve as binder between solid particles in the technique of building materials. They include polymers by means of which materials containing, for example, cellulose, lignin, or keratin can be bonded. As an example of a suitable agent, mention may be made of binders used in the paper or textile industry for paper pulps or textile pulps, finishing agents or else various binders used in paints

  or coatings in the building industry, to serve as binders for the pigment particles contained therein.

  As in the case of the impregnating agents according to the invention described above, one can also classify the

  polymers capable of serving as binders in natural products and synthetic products.

  Natural polymers, such as starch and its derivatives, cellulose ethers, such as carboxymethyl cellulose, or hydroxyethylcellulose, cellulose esters, such as cellulose acetate, soy proteins, casein, and alginates, generally have hydrophilic properties. These polymers are suitable binders, but they are preferably combined with the

  synthetic polymers described below.

  Synthetic polymers have mainly hydrophobic properties, which can be modified & desired using hydrophilic comonomers. Those skilled in the art know many polymers of this type, including

  some, particularly suitable according to the invention, are indicated below.

  Preference is given to homopolymers or copolymers which can be obtained by polymerization of different monomers, such as vinyl esters, acrylates, methacrylates, vinyl aromatic compounds, α-olefins, acrylonitriles. It is understood that these monomers can also be used as comonomers. In addition to these principal monomers, it is also possible to use, in smaller quantities, so-called adjuvant monomers such as acrylamides, mono and di-carboxylic acids a, B monoethylenically unsaturated, such as acrylic acid, methacrylic acid. , crotonic acid or maleic acid, hydroxyalkyl acrylates, hydroxyalkyl metacrylates, cellulosic ethers or cellulose esters. The binder may contain at least one aqueous or organic solution or dispersion of a polymer; we use

  preferably solutions or dispersions of the polymers described above, the dispersions of polyvinyl esters5 and of poly (meth) acrylates here being of particular interest.

  This also includes polymers which may optionally contain, for example, one or more of the comonomers and / or adjuvant monomers of the type mentioned.

above.

  According to a preferred embodiment, the binder comprises a dispersion of polyvinyl acetate.

  As in the case of impregnating agents, those skilled in the art also know many methods of manufacturing the binders described above. The concept of binder therefore also includes, within the framework of the present

  invention, optional adjuvants or additives which are usually used in the manufacture of these polymers and which have already been mentioned in the context of the description of the impregnating agents.

  When the binder is present as a dispersion solution, its solids content is usually

  from 5 to 70% by weight, preferably from 2 to 60% by weight, relative to the total weight of the agent.

  Materials which can be formed into a shaped body by means of the method according to the invention include fibers, but also fibrous elements. This includes, for example, natural fibers including plant fibers, but also animal fibers can be used according to the invention. Usable fibers come for example from various fibrous plants such as cotton, flax, hemp, ramie, jute, loofah, sisal, Manila hemp, hemp from Mauritius, Jucca fiber, New Zealand hemp, seaweed, Esparto and coconut fiber. Wool, hair and silk are examples of animal albuminous fibers, of which the hair is used in a preferred manner. We must add fibrous elements based on plants that are not literally part of natural fibers. In this context, the most interesting are plant elements, which can be used at will in dried form. Examples include stems and leaves of common crops, for example

  example of cereals, legumes or oilseeds.

  A very particular embodiment relates to the transformation, according to the invention, of straw, a term which includes in the broadest sense of the dried fibrous plant elements, but which includes in particular strands and

cereal leaves.

  It is possible to produce such fibrous plant elements or natural fibers according to the usual methods.

  It is not strictly necessary here to remove partially or completely, fibers or fibrous elements, the remaining components. It may however be advantageous, in certain particular cases, to carry out such a separation, in the known manner for example for obtaining high quality fibers to be used as reinforcing fibers or fibers for the constitution of nonwovens. Depending on the purpose of use, it may be appropriate to transform the fibrous plant elements or natural fibers by mechanical fragmentation into a mixture of particles which then has a particle size.

  substantially uniform. This fragmentation can be carried out before and / or after impregnation. Preferably finely chopped straw.

  Depending on the type and purpose of use of the form bodies to be produced according to the method of the invention, other processing steps may also be provided. It is possible, for example, to bleach fibrous plant elements and / or natural fibers in the usual manner if a clear material is desired. However, it must be guaranteed

  that the impregnation is not decisively influenced by the bleaching process.

  One or more adjuvants can also be added at will. It is for example possible to add a flame retardant compound, such as antimony oxide, iron sulphate, alum, bismuth oxide, urea phosphate, or chloroparaffin, preservatives such as bactericides, colors or flavors. Such adjuvants15 can be introduced at an appropriate stage of the process, for example during the impregnation or during the mixing of the

material impregnated with a binder.

  We prefer shaped bodies whose biological degradation is rapid.

  When the vegetable elements and / or the impregnated natural fibers have been mixed with a binder and possibly with other adjuvants, the last process step consists in the configuration. This step includes taking the binder and the actual configuration. The outlet can be adjusted as a function of time and by choosing an appropriate temperature. The configuration is carried out by mechanically supporting the deformable mixture, compression in a mold under pressure at high temperature being generally carried out. These two processes can be executed in parallel. It may also be appropriate to first partially set a mixture whose original viscosity is relatively low, in order to obtain a mixture with relatively high viscosity which can then

  be transformed under pressure to constitute the desired shape body.

  According to a preferred embodiment, an appropriate partial setting of the mixture gives a mass to be formed which can be stored stably for a certain period of time and which can be subjected subsequently to the step of

final configuration.

  The object of the present invention therefore also relates to materials composed of fibrous plant elements and / or natural fibers which can be impregnated according to the invention and which can constitute, by the addition of a binder, a deformable and / or formed mass. This includes, on the one hand, partially taken mixtures of fibrous plant elements and / or natural fibers impregnated with a binder, which are, depending on their viscosity, in the form of a viscous mass or a deformable solid mass. The materials

  composites according to the invention also comprise, on the other hand, mixtures whose setting is complete and which are no longer deformable, or only under defined conditions.

  The final configuration logically depends very closely on the purpose of using the shaped bodies produced according to the invention. Among the many

  employment possibilities, only a few will be given by way of example in the context of the present description. Mention may be made, as examples, of various containers, for example goblets or flowerpots, or elements of

  construction like floor, wall or roof slabs.

  The following examples explain the invention without limiting it.

  Example i: Oat straw goblet. finely chopped barley, seicle or wheat 1 kg of finely chopped straw is soaked with a polyacrylate dispersion, for example the product marketed by Sikkens GmbH, under the trade name of SIKKENS BARROL GRUNDHARTER, on5 diluted in water at a volume ratio of 1: 4 and allow to soak until the finely chopped straw no longer absorbs any liquid. The mixture is then dried. 30% by weight of a dispersion of polyvinyl acetate is added to this impregnated straw, for example the product sold as a binder for paper and textile pulps by the company Jowatex under the name

  JOWATEX (R) sales representative. This mixture is then dried at 30 ° C. and then compressed under pressure at 120 ° C. to form a cup of the desired shape. Such a cup is particularly suitable as disposable tableware.

  It is possible to make other containers in the same way such as plates or flower pots. Example 2: Insulating roofing sheet in oat straw. barley, rye or wheat 1 kg of chopped straw is impregnated with a finishing agent, as described in Example 1. This mixture is then dried and then mixed with 20% by weight of the dispersion 25 d polyvinyl acetate described in Example 1 as well as a flame retardant and a preservative. This mass to be formed

  is dried at 25 C and then compressed to 150 C to form an insulating roofing plate. The resulting plate is strong enough to allow the attachment of fasteners such as dowels or screws.

Claims (11)

  1. Process for manufacturing shaped bodies of fibrous plant elements and / or natural fibers, in which these fibrous plant elements and / or natural fibers are impregnated, at will dried, treated with a binder and the mixture is then trained,   characterized in that the impregnating agent used is a priming agent for plasters in the building industry.   2. Method according to claim 1, characterized in   that the impregnating agent contains at least one aqueous or organic solution or dispersion of a polymer.   3. Method according to claim 2, characterized in that the polymer is chosen from the group consisting of   polyacrylates, polymethacrylates, acrylatesmethacrylates or styrene-butadiene copolymers.   4. Method according to one of the preceding claims, characterized in that the binder comprises at   minus a polymer used in the technique of building materials to bond solid particles together.   5. Method according to claim 4, characterized in that the binder comprises at least one polymer which can be obtained from polymers which are chosen from the group consisting of vinyl esters, acrylates, methacrylates, vinyl aromatic compounds, a-25 olefins, acrylonitriles, acrylamides, mono- and di-carboxylic acids a, B monoethylenically non   saturated, such as acrylic acid, methacrylic acid, crotonic acid or maleic acid, hydroxyalkyl acrylates, hydroxyalkyl metacrylates, cellulose ethers or cellulose esters.   6. Method according to claim 4 or 5, characterized in that the binder contains at least one solution or one   aqueous or organic dispersion of a polymer.   7. Method according to one of claims 4 to 6,   characterized in that the binder comprises a dispersion of polyvinyl acetate.   8. Method according to one of the preceding claims, characterized in that straw, in   In particular, straw from cereal crops, preferably in highly fragmented, crushed and / or finely chopped form, is used.   9. Method according to one of the preceding claims, characterized in that the formation comprises the   the steps of partially letting the   mixing, then giving it the final configuration, preferably under pressure and at a higher temperature.   10. Shaped bodies of fibrous plant elements and / or of natural fibers, characterized in that they have been impregnated with a finishing agent for plasters.   the building industry and were provided with a binder, before being configured.   11. Shaped body according to claim 10, characterized in that they can be produced according to one   the methods of claims 1 to 9.