FR2966148A1 - Granulate, useful for the fabrication of a dry floor coating, comprises fine flax and fine hemp - Google Patents

Abstract

Granulate comprises 5-80 wt.% of fine flax and 5-80 wt.% fine hemp. An independent claim is included for a preparation of the granulate, comprising: (a) preparation of a mixture of fine flax and hemp in a suitable proportion adapted for the preparation of the granulate, and (b) forming the granulate by compression of the obtained mixture.

Description

Granulate for dry screed

TECHNICAL FIELD The present invention relates to an insulating granulate which is thermally and acoustically insulative. State of the teehmique A "dry screed" differs from a charge called "wet" in that its manufacture does not require the addition of a liquid. The material used is conventionally made of a set of granules or balls which, after spreading and leveling, constitute a layer or "load" capable of supporting a floor. A dry screed has the advantage of being light, quick to manufacture (no drying, ease of implementation) and have thermal and acoustic insulation qualities. Dry screeds made from polystyrene plates are particularly known. The manufacture of these screeds however requires cuts and generates falls. Dry screeds made of wood pellets are also known. These screeds, however, tend to deform under the effect of a permanent or variable load. In some cases, the deformation can even become permanent. There is therefore a need for granules for producing a dry screed having improved compression behavior. An object of the present invention is to provide a granulate at least partially meeting this need. SUMMARY OF THE INVENTION For this purpose, the invention proposes a granule, in particular intended for thermal and acoustic insulation, comprising, in percentages by weight relative to the total mass of said granule, between 5 and 80% of linseed fines. and between 5 and 80% of hemp fines. Preferably, the constituents derived from flax or hemp, preferably flax and hemp, together represent more than 80%, more than 90%, more than 95%, or even substantially 100% of the mass of the granule. As will be seen in more detail in the following description, a dry screed made from granules according to the invention has excellent compression behavior. Such a granule also provides good acoustic and thermal insulation. Finally, such granules have the advantage of including flax and hemp fines, which are usually waste products of the processes for making flax or hemp products. Preferably, a granule according to the invention has a relative humidity of less than 12%, preferably less than 10%, preferably less than 9%, preferably less than 8%. Preferably, the flax fines are present in said granule according to the invention in a content of between 10 and 80%, between 20 and 60%, between 30 and 50%, more preferably between 40 and 45%, in percentages by weight relative to the total mass of said granule. Preferably, the hemp fines are present in said granule in a content of between 10 and 80%, between 20 and 60%, between 30 and 50%, more preferably between 40 and 45%, in percentages by weight relative to to the total mass of said granule. Preferably more than 60%, more than 70%, more than 80%, more than 90% by number of the fines. flax have a size preferably greater than 0.01 mm, preferably greater than 0.1 mm, and / or less than 4 'mm, preferably less than 3 mm, less than 2 mzn, or even less than 1 mm. Preferably, more than 60%, more than 70%, more than 80%, more than 90% by number of the hemp fines have a size preferably greater than 0.01 mm, preferably greater than 0.1 mm, and / or less than 4 mm, preferably less than 3 mm, less than 2 mm, or even less than 1 mm. Preferably, the flax fines have an average size of 0.01 to 3 mm and the hemp fines have a mean size of 0.01 to 3 mm. an average size of between 0.01 and 5 mm and the hemp fines have an average size of between 0.01 and 5 mm.

Preferably, the flax fines have an average size of between 0.1 and 2 mm and the hemp fines have an average size of between 0.1 and 2 mm. A granule according to the invention may further comprise a quantity of resinous or leafy wood fines of less than 5%, preferably less than 2%, preferably less than 1%. Preferably, a granule according to the invention has substantially no resinous or hardwood wood fines. According to a preferred embodiment, a granule according to the invention comprises, in percentages by weight relative to the total mass of said granule and for a total of 100 ° / n: between 45 and 50% of flax fines, between 45 and 50% of hemp fines, and between 0 and 10% of a binder. Preferably, a granule according to the invention comprises less than 20%, less than 15%, less than 10%, or even less than 5% of hemp or flax fibers. Advantageously, the stiffness and the compressive strength of the granules are improved. A granule according to the invention is preferably cylindrical. It preferably has a diameter greater than 3 mm, preferably greater than 4 mm, and / or less than 10 mm, preferably less than 8 mm. The length of the granule is preferably greater than 5 mm, preferably greater than 10 mm. mm, greater than 15 mm, greater than 20 mm and / or less than 40 mm, preferably less than 30 mm, preferably less than 25 mm, and preferably less than 20 mm. The invention also relates to a set of granules according to the present invention. Advantageously, such a set of pellet pellets and a patch of quality for poor or uneven floors, that is to say yin leveling with low risk of collapse. The invention also relates to a dry screed consisting of a set of granules according to the invention. The invention also relates to a method of manufacturing a dry screed comprising the following steps: A) spreading granules according to the present invention on a floor, so as to obtain a layer of granules; B) leveling said layer, for example using guiding rules and a draft rule, so as to obtain a level layer; C) optionally, tamping the leveled layer, for example using a roller, so as to obtain a groomed layer; D) optionally, placing load distribution panels on the groomed layer, or on the leveling layer; E) placing a floor resting on the load distributing panels or on the danced layer, or even on the leveled layer, said floor being able for example of wood or plaster, or any other material known to the skilled person. Such a method advantageously makes it possible to level the ground simply, and to ensure good theinlique and acoustic insulation. Advantageously, such a layer leveled. or groomed has a low rate of subsidence. The set of granules can therefore advantageously be used for the renovation of floors, especially the renovation of attics. Advantageously, the layer leveled, or tamped, does not require drying time before the establishment of splitter panels or dis floor. In one embodiment, this method does not include step C). In one embodiment, said method does not include step D). In one embodiment, said method has neither step C) nor step D). Preferably, the granular layer after leveling has a thickness greater than 1 cm, even greater than 2 cm, or even greater than 5 cm, and / or less than 20 cm, or less than 15 cm, or even less than 10 cm. In a preferred embodiment, if the granular layer after leveling has a thickness greater than 10 cm, the spreading is carried out in two successive steps, for example to spread two layers of average thickness substantially equal to the half of the final average thickness. The invention finally relates to a method for producing a granule according to the invention, said process comprising the following successive steps: a) preparation of a mixture of linseed fines and hemp fines in proportions suitable for manufacture a granule according to the invention; b) fofine said mixture so as to obtain a granule, for example in a press chamber of a press, this operation being called "granulation". Definitions A "granule" is a particle comprising a set of agglomerated fines, preferably by compression, and having a size of between 5 and 40 mm. A set of granules, or "granule powder", is a particulate set of granules. "Fiber" is a filamentary substance derived from the fibrous peripheral portion of a straw and having a length more than 10 times greater than its largest dimension in any transverse plane, called "width", the transverse planes being the cutting planes. the fiber perpendicular to the direction of its length. The ratio of width to length is called "sphericity". A "fine" is a particle from the fibrous peripheral portion or the central portion of a straw and having a morphology allowing it to pass through a square mesh screen whose opening has a side of a length of 5 mm. The "size" of a granule or a fin is defined by the length of the side of the smallest square mesh of a sieve through which the granule or fine may pass. The average length of a set of granules is the arithmetic mean of the lengths of these granules. The average diameter of a set of granules is the arithmetic average of the diameters of these granules. Unless otherwise indicated, throughout the description, the percentages mentioned are percentages by weight. Unless otherwise indicated, "comprising" OR "comprising" means "comprising at least".

BRIEF DESCRIPTION OF THE FIGURES Other features and advantages of the invention will become apparent on reading the following detailed description and on examining the accompanying drawings in which: FIG. 1 shows the results of the monotonic compression tests; , s corresponding to the deformation, cs corresponding to the load (in MPa), and EP EP n ° 2 and EP n ° 3 designating the curves obtained with the three samples tested; FIG. 2 represents the results of monotonic and dynamic compression tests carried out on a fourth sample; FIG. 3 represents the results of the tests carried out to evaluate the creep resistance; and - Figure 4 shows, in cross section, a flax straw or hemp. DETAILED DESCRIPTION OF THE EMBODIMENT As explained, a granulate according to the invention can be manufactured according to the above mentioned steps a) and b). Preferably, the fines have a morphology allowing them to pass through a square mesh screen whose opening has a side of a length of less than 4 mm, preferably less than 3 mm, more preferably less than 2 mm, of more preferably less than 1 mm. Preferably, the fines are derived from a defibration of flax straw and hemp straw. As shown in FIG. 4, a straw 10 of flax or hemp has a fibrous peripheral portion 12 and a central portion 14, more rigid than the fibrous peripheral portion 12 and sometimes called "wood". The hemp and flax straws used can come from organic farming, that is to say from crops using little or no phytosanitary treatment inputs, insecticides, or even no chemicals. In particular, hemp straw may have undergone no treatment, which advantageously limits the allergenic risks for the end user. The absence of treatment also avoids any degradation of the properties of the material. Preferably, the flax fines are derived from one or more of the following flax varieties: Everest® and Banquise®.

Preferably, the hemp fines are derived from one or more of the following varieties of hemp: Futura 75e, Epsilon 68e, Santhica 27e, Fedora 17 BIOe, Uso 31 BlOe. The defibration of hemp straw and / or flax may be mechanical or chemical. Mechanical grinding involves grinding and separating the rigid central part (flax shives, hemp groves and fines) and the peripheral part (fibers and non-fibrous fines) of the straw. The fines are obtained by sieving the two mills containing central and peripheral portions of the straws, respectively, by means of sieves of square mesh 10, the side of which preferably measures 2 mm. Preferably, the tanning conditions, and in particular the sieving time, are adapted so that the fraction obtained from the milling of the peripheral and sieve-passing parts (fines) comprises less than 10%, preferably less than 5% of fibers. The fines resulting from the sieving of the two ground materials are then combined. The fines therefore correspond to small particles generally (typically at least 90% by number) having a sphericity greater than 0.1. Some fines may have a sphericity of less than 0.1. Conventionally, at least 90% by number of the fines having a sphericity less than 0, lsont from the central parts of the straws 14 and therefore have a certain rigidity (unlike fibers). The defibration of hemp straw conventionally makes it possible to obtain between 15 and 20% of fines, in percentages of finasse relative to the total mass of hemp straw. The defibration of the flax straw conventionally makes it possible to obtain between 10 and 40% of fines, as a percentage by weight relative to the total mass of the treated flax straw. In step a), hemp fines and linseed fines are mixed and mixed to obtain the most homogeneous feedstock possible. Preferably, the starting charge comprises no other component than hemp and flax fines. The starting charge may however be adapted so that the granules according to the invention comprise less than 5%, preferably less than 2%, preferably less than 1%, and / or preferably more than 0.1%, of preferably more than 0.2%, preferably more than 0.5%, of additional constituents which can advantageously bring additional technical specificities to the granule according to the invention or contribute to improving those which it already possesses, for example fire resistance. , resistance to moisture, thermal and / or acoustic insulation, mechanical performance (resistance to tensile, shear and / or compression force). The additional components may also have antifungal effect or be a binding agent.

Preferably, the flax and hemp fines together account for more than 80%, more than 90%, or even more than 95%, of the total scum of the granule. Preferably, flax fines, hemp fines, and optional additional components together account for more than 90%, or even more than 95% or even substantially 100% of the total mass of the granule.

Preferably, no liquid is added to the feedstock. Preferably, at least 90% by number of the fines have a size of less than 2 mm, or even less than 1 mm. Preferably, the relative humidity level of the mixture at the beginning of step b) is less than 1.7%, preferably less than 15%, preferably less than 13%, preferably less than 11%. In step b), this mixture is granulated. For this purpose, the mixture is compressed. Preferably, the compression is carried out at a pressure greater than 80bars, or even greater than 100bars, or even greater than 120bars, and / or less than 1.80bars, or even less than 160bars, or even less than 140bars. Preferably the pressure is substantially equal to 130bars. Preferably, the compression induces a compression ratio of the mixture resulting from step a) greater than 1.5, or even greater than 20, or even greater than 25, and / or less than 40, or even less than 35, or even less than 30. Preferably, the compression ratio of the mixture resulting from step a) is substantially equal to 28. Advantageously, this compression makes it possible to manufacture dense and rigid granules without other constituents than flax and hemp fines. Preferably, the mixture is then extruded, in the form of a boûdin regularly cut to obtain granules of the desired length, preferably the maximum distance between the respective lengths of any granule and the average length of the granules is less than 10%, or even less than 5%, or even less than 2%. Preferably, step b) comprises a step of cooling the granules thus obtained. Preferably, the relative humidity level in the granules leaving the cooler is less than 12%, preferably less than 10%, preferably less than 9%, preferably less than 8%. The granules can be bagged at the outlet of the cooler. The thermal conductivity of the granules is preferably less than 1 W / m · K, preferably less than 0.5 W / m · K, and preferably less than 0 · IW / m · K. The density of the set of granules produced by this method, poured and distributed homogeneously manually (without sorting or alignment of the granules, and without compression of the set of granules), is preferably between 300 and 1000 kg / m ~, preferably between 400 and 800 kg / m 3, more preferably between 650 and 750 kg / m 3. The diffusion resistance of the steam of the set of granules is preferably less than 10 mg / m 2 / h. Pa, preferably less than 5 mg / m2.h.Pa, preferably less than 2 mg / m2.h.Pa. Preferably, a granule according to the invention is extruded. Preferably, it. has a cylindrical shape, of diameter D and length L. The diameter D of the granule is preferably greater than 3 mm, preferably greater than 4 mm, and / or less than 10 mm, preferably less than 8 mm. The length L of the granule is preferably greater than 2 mm, preferably greater than 5 mm, preferably greater than 10 mm, greater than 15 mm, greater than 20 mm and / or less than 50 mm, preferably less than 30 mm. preferably less than 25 mm.

The cylindrical morphology advantageously allows the formation of a low density screed, but very resistant to compression, without damage.

Tests The tested granules were produced by a process comprising the steps a) and b) described above. In step b), the compression of the mixture resulting from step a) was carried out under a pressure of 130 bars, for a compression ratio of 28. The relative humidity of the mixture resulting from step a) was less than 11%, and the moisture content of the product at the outlet of the cooler was substantially equal to 8%.

The granules having, at the end of step b), the following characteristics: Density of the set of granules 650 kg / m 3 Diameter 6 mm Thermal conductivity 0.06 W / m K Resistance to the diffusion of water vapor 1 2mg / m2.h.Pa Surface settlement in situation 1 to 2% The monotonic compression tests are carried out on three sets of successive granules, resulting from the same manufacturing process, according to the invention: a non-deformable diameter steel mold 150 mm and a height of 151 mm is filled by pouring then homogeneous manual distribution. No sorting or alignment of the granules is performed. A piston then compresses the granules by sinking at a constant speed into the mold. The results of monotonic compression at 0.2 mm1s, under oedometric conditions, are presented in FIG. 1. The three curves are superimposed relatively well, which shows that the granule manufacturing procedure makes it possible to obtain substantially identical mechanical properties for different sets of granules. 4n obtained by this method an average initial module (with substantially zero charge) of 2.4MPa. This means that a load of 1000 kg / m2 would result in a settlement of 4.2 mm for a thickness of 1 μm granules.

In addition, once packed, the behavior of the set of granules stiffens and. the settlement decreases. Figure 2 shows the monotonic compression curve and the dynamic compression curve for a fourth sample. For dynamic compression, charge-discharge cycles are repeated three times, the granules being arranged in a mold identical to that described above. Figure 2 shows the consistency of the dynamic compression results with those obtained by previous tests. The elastoplastic behavior of the set of granules under variable compression loading is also observed. During the discharge, the whole exhibits an almost exclusively elastic behavior (very little plastic). Advantageously, a clevis made of a set of granules according to the invention does not deform substantially plastically and thus regains its original dimensions when a compressive load is rapidly applied and then removed.

Creep tests were then conducted on the sample having undergone the dynamic compression test (and having therefore already undergone a stress of 0.35 MPa). For this purpose, the tests are controlled under load with a crushing speed of 0.121cN / s applied to the sample. Three successive stop and hold ranges at 0.34 MPa are applied. Displacements are then recorded over a period of 5 minutes as a function of time. Figure 3 shows the evolutions of the two load and displacement curves as a function of time. It appears a creep. The set therefore has a viscous component, but it remains relatively modest. In addition, this component decreases rapidly over time: for example, it is substantially divided by three during the third phase compared with the first phase. During the intermediate phases of the test, the stress is greatly reduced. It is then possible to read the permanent deformations on the sample, of the order of 0.003 mm for a height of 151 mm, an average deformation of 2.10 "5.

In conclusion, it appears that the granules used in bulk, without a binding agent, exhibit a highly elastic elastoplastic behavior. A very weak viscous component leads to small delayed deformations. The initial module is of the order of 2.4MPa. It increases rapidly under load and reaches 1 MPa for a load of the order of 0.7 MPa.

These characteristics make the granules according to the invention very well suited to the manufacture of dry fillers. In particular, the behavior of the screeds manufactured with granules according to the invention appears to be superior to that of fillers manufactured with wood-based granules known to the inventors. Of course, the invention is however not limited to the embodiments described above, provided for illustrative and non-limiting purposes,

Claims (15)

REVENDICATIONS1. Granule comprising, in percentages by weight relative to the total mass of said granule, between 5 and 80% of flax fines and between 5 and 80% of hemp fines. 2. Granule according to the preceding claim, comprising between 30 and 50% of flax fines and between 30 and 50% of hemp fines, in percentages finasse relative to the total mass of said granule. 3. Granule according to any one of the preceding claims, wherein the flax fines have an average size of between 0.01 and 5 mm and the hemp fines have an average size of between 0.01 and 5 mm. 4. Granule according to any one of the preceding claims, wherein the flax fines have an average size of between 0.1 and 3 mm and the hemp fines have an average size of between 0.1 and 3 mm. 5. Granule according to any one of the preceding claims, not comprising a binding agent. 6. Granule according to any one of the preceding claims, wherein the fines of flax and / or hemp are substantially free of pesticide traces. Granule according to any one of the preceding claims, in which the flax fines and the hemp fines together account for more than 90% of the total mass of the granule. Granule according to any one of the preceding claims having a cylindrical shape. 9. Granule according to the preceding claim, having a diameter greater than 4 mm and less than 8 mm and having a length greater than 10 mm and less than 25 nm. 10. Granule according to any one of the preceding claims having a relative humidity of less than 12%. 11. Granule according to any one of the preceding claims having a relative humidity of less than 10%. 12. Granule according to any one of the preceding claims, having a fiber content of less than 20%, as a percentage by weight based on the mass of the granule. 13. A method of manufacturing a granule according to any one of the preceding claims, comprising the following steps: a) Preparation of a mixture of linseed fines and hemp fines in proportions suitable for the manufacture of a granule according to any one of the preceding claims; b) Press-forming said mixture to obtain a granule. 14. Process according to the preceding claim, in which the fines are prepared by grinding straw of flax and / or hemp straw and then sieving through a sieve of square mesh whose side length is less than 3 mm. 15. Use of a set of granules according to any one of claims 1 to 12, or from a process according to claims 13 or 14, for the manufacture of a dry screed.