METHOD FOR PRODUCING AN OPTIMIZED LOOSE INSULATION MATERIAL AND INSULATION STRUCTURE WITH SUCH A MATERIAL

Description

technical field

[0001] The present invention relates to the general technical field of loose-fill insulation materials used in new or renovated buildings. These materials are generally intended to improve the thermal performance of an attic, an intermediate floor, or an exterior wall. These loose-fill insulation materials can also be incorporated into prefabricated modular timber structures or prefabricated composite timber-concrete structures by blowing them in.

[0002] In France and other countries, public and private tender specifications increasingly require the use of bio-based insulation materials with the lowest possible environmental footprint. These insulation materials are made, for example, from renewable and recyclable raw materials such as wood fibers, cellulose wadding, textile fibers, expanded cork, hemp, sheep's wool, or other bio-based materials.

[0003] The term “bio-based materials” refers to materials derived from renewable organic matter (biomass) of plant or animal origin.

[0004] The invention relates more particularly to the manufacture of bulk bio-based insulating materials as well as the design and manufacture of insulating structures incorporating such materials. Previous technique

[0005] We are familiar, for example, with the use of loose mineral wool intended to be blown into attics or blown into a hollow wall partition.

[0006] However, such an insulating material has a density of approximately 40 kg / m³, which may prove insufficient, depending on the applications considered, to protect against summer heat if one wishes to obtain true thermal comfort.

[0007] Most known loose-fill insulation materials are not bio-based. Mineral wool and hybrid wools are examples. Furthermore, these loose-fill materials offer insufficient insulation performance in summer.

[0008] Bio-based products available on the market, such as cellulose wadding, typically have a fire rating of E or F. This poor performance necessitates the addition of fire-resistant materials, for example, in the design of insulating walls. This results in higher costs for these solutions. Furthermore, the use of these non-bio-based fire-resistant materials negatively impacts the carbon footprint of these solutions.

[0009] As an example, document EP 2 204 483 discloses a manufacturing process for loose-fill insulation in which cellulose wadding is mixed with animal or plant fibers. The weight ratio of cellulose wadding to the total mass is 35% to 60%. This high proportion of cellulose wadding is not sufficient to give the insulating material significant thermal and environmental performance. Presentation of the invention

[0010] The object of the invention is therefore to overcome the disadvantages of the prior art by proposing a new process for manufacturing a bio-based insulating material in bulk, from raw materials that are ecological, renewable, recyclable and available in almost all rural areas.

[0011] Another object of the invention aims to propose a method for manufacturing bulk insulating material, free from boron salt.

[0012] Another object of the invention is to propose a method for manufacturing bulk insulating material that is easy to implement and economical.

[0013] Another object of the invention is to provide a new insulating material in bulk, which can be blown or injected into cavities and which has excellent thermal and acoustic insulation performance.

[0014] Another object of the invention aims to provide prefabricated modular insulating elements, incorporating the new insulating material and exhibiting excellent fire resistance, thermal and acoustic insulation performance.

[0015] The objects assigned to the invention are achieved using a process for manufacturing a bulk insulating material based on cereal straw, characterized in that it comprises the following steps: a) Mechanically shred the straw to obtain defibrated straw with an average length of strands between 3 mm and 22 mm, and preferably between 3 mm and 11 mm, and an average diameter between 0.5 mm and 4.0 mm, and preferably between 0.5 mm and 2.5 mm; b) Use cellulose wadding and untangle and aerate said cellulose wadding; c) Use a mixer and mix the defibrated straw from a) and the cellulose wadding prepared from b), said cellulose wadding being introduced into the mixer in a proportion by mass between 1% and 30%, relative to the total mass of the defibrated straw and cellulose wadding; d) Inject compressed air into the mixer to homogenize said mixture and to obtain a mixture with a density between 55 kg / m³ and 65 kg / m³; and e) Bag the mixture of the insulating material thus obtained.

[0016] According to one example of implementation, the process consists in step a) of using at least one shredder to shred and grind the straw into bales, said at least one shredder comprising adjustable shredding / grinding tools to define the shape and size properties of the resulting defibrated straw strands, said tools comprising in series knives and hammers.

[0017] As an example, the process consists in step c) of using at least one mixer of the rotary cylinder type and / or dropping cage type.

[0018] According to one implementation example, the process consists of filtering the defibrated straw obtained under a) to remove dust and other impurities to a mass proportion of at least 2% and preferably at least 5% to 10% of the defibrated straw. This filtration advantageously reduces the risk of explosion at the manufacturing site due to a high concentration of dust in the air.

[0019] According to one example of implementation, it consists of mixing cellulose wadding or a mixture of cellulose wadding and defibrated straw, with one or more adjuvants including a fungicide product.

[0020] According to one example of implementation, the process consists of mixing cellulose wadding or the cellulose wadding - defibrated straw mixture, with one or more additives, including at least one fire retardant product with a mass proportion relative to the total mass of the products mixed under c), of between 10% and 30%.

[0021] The fire retardant product, for example, is chosen from a family of geo-sourced products.

[0022] According to another example of implementation of the process, the fire retardant product is in viscous or liquid form and comprises a geopolymer of the metakaolin type.

[0023] The objects assigned to the invention are also achieved using a prefabricated modular wooden structure for constructing a partition or wall, or for cladding a wall of a building, on the exterior or interior side. This structure advantageously comprises at least one cavity containing the insulating material obtained according to the manufacturing process detailed above.

[0024] The objects assigned to the invention are also achieved using a prefabricated modular structure made of mixed wood and concrete to create a partition or wall, or to clad a wall of a building, on the exterior or interior side. This structure advantageously comprises at least one cavity containing the insulating material obtained according to the manufacturing process described above.

[0025] The process according to the invention provides the remarkable advantage that the insulating material obtained comprises cereal straw, which is available in large quantities and in almost all regions.

[0026] Furthermore, the straw requires no prior treatment before being manufactured into loose-fill insulation according to the process described in the invention. The straw can therefore be stored as is, immediately after harvesting, pending its processing to manufacture the insulation material.

[0027] Furthermore, the loose insulating material obtained with the process according to the invention includes a product that is very interesting from an ecological point of view, namely straw, which has CO2 storage / emission performance that is significantly superior to the performance of other insulating materials, namely wood wool, cellulose wadding, grass wool or hemp wool.

[0028] Another advantage of the loose-fill insulation material obtained using the process according to the invention is that it is perfectly suited to existing blowing devices that typically operate with other loose-fill insulation materials. Users of this new loose-fill insulation material can therefore retain their existing blowing or injection equipment without modification.

[0029] The material obtained using the process according to the invention also exhibits remarkable performance. Indeed, this material has a thermal conductivity coefficient lambda- (W / mK) of 0.038, which is remarkable, given that the thermal conductivity coefficient is between 0.052 and 0.080 for straw, between 0.037 and 0.044 for expanded cork and between 0.037 and 0.042 for cellulose wadding.

[0030] The material obtained according to the process according to the invention also exhibits, surprisingly, great lightness and great homogeneity. Brief description of the figures

[0031] Other features and advantages of the present invention will become more apparent upon reading the following description, made with reference to the attached drawing, given by way of non-limiting example, in which: there figure 1 is a schematic view of a flowchart of an example of implementation of the manufacturing process of a bulk insulating material according to the invention. Detailed description of the invention

[0032] There figure 1 illustrates, using a flowchart, an example of the implementation of a process for manufacturing a bulk insulating material from cereal straw, such as wheat, barley, oats, rapeseed, miscanthus, rice straw or various mixtures thereof.

[0033] The installation includes, for example, a shredding and defibrating unit 1 which transforms raw straw into defibrated straw by shredding and grinding.

[0034] The shredding and defibrating unit 1 advantageously includes tools for cutting and breaking the straw strands. For example, the shredding and defibrating unit 1 comprises two shredders connected in series. The first shredder includes, for example, tools for cutting the straw strands, such as knives. The second shredder includes, for example, tools for breaking the straw strands, such as hammers.

[0035] By defibrated straw, it is appropriate to understand a straw comprising non-homogeneous strands of average length between 3 mm and 22 mm and preferably between 3 mm and 11 mm and whose average diameter is between 0.5 mm and 4.0 mm and preferably between 0.5 and 2.5 mm.

[0036] The average diameter should be understood as the largest dimension of the straw strand, taken in a plane orthogonal to the longitudinal direction of said strand.

[0037] As an example, a defibrated straw comprises 29% to 33% of strands with an average length of 9.633 mm and an average diameter greater than 2 mm, 32% to 37% of strands with an average length of 6.951 mm and an average diameter greater than 1 mm and 16% to 20% of strands with an average length of 3.960 mm and an average diameter greater than 0.5 mm.

[0038] The remainder of this sample sample is considered to be dust, which is preferably removed by filtration using a filtration / dosing unit 2.

[0039] The process is implemented, for example, using an installation schematically illustrated with the flowchart of the figure 1 .

[0040] The installation includes a shredding and defibration unit 1 fed with straw, for example, baled or bundled. The shredding and defibration unit 1 comprises, for example, two shredders in series, which may include shredding tools with specific shapes or settings. Each shredder thus includes adjustable cutting, bursting, and / or shredding tools to define the shape and size parameters of the defibrated straw strands.

[0041] According to another example of the installation, the shredding and defibration unit 1 includes knives for cutting the straw strands and hammers for breaking them apart. During the straw shredding process, one or more passes through the shredding and defibration unit 1 may be required. The number of passes depends on the desired morphology (shape, length, and diameter) of the defibrated straw strands. The resulting defibrated straw, exiting the shredding and defibration unit 1, is composed of strands optimized in terms of size and shape to facilitate mixing with the cellulose wadding and to improve the thermal and acoustic insulation properties of the resulting insulating material.

[0042] According to one embodiment, the installation also includes a filtering and dosing unit 2 which directly feeds a mixer 3.

[0043] The filtering operation is carried out, for example, using a vibrating sieve and / or a cyclone separator. The latter can be advantageously used to transfer the shredded straw to mixer 3. The filtering process separates the shredded straw from dust and other impurities by gravity or cyclone filtration.

[0044] Mixer 3 includes, for example, at least one mixer of the rotary cylinder type and / or dropping cage.

[0045] The installation also includes a first dosing and spraying unit 4a to supply the mixer 3 with adjuvants. These include at least one fungicidal adjuvant F. These adjuvants may also include a fire-retardant adjuvant R.

[0046] The installation also includes a second dosing and spraying unit 4b to supply the mixer 3 with cellulose wadding. Advantageously, the installation includes a loosening and aeration unit 5 to decompact the cellulose wadding before it is dosed and sprayed into the mixer 3. One loosening and aeration unit 5 includes, for example, a carding system.

[0047] The installation also includes a compressor 6 to inject compressed air into the mixer 3, thus promoting the homogenization and aeration of the mixture.

[0048] The installation also includes a bagging and palletizing unit 7 for the insulating material at the outlet of the mixer 3.

[0049] The loose insulating material is therefore manufactured according to the manufacturing process according to the invention and detailed below.

[0050] The manufacturing process of the bulk insulating material based on cereal straw includes a step a) consisting of mechanically shredding and grinding the straw to obtain defibrated straw whose strands preferably have an average length between 3 mm and 11 mm and an average diameter between 0.5 mm and 2.5 mm.

[0051] Advantageously, the process consists of filtering the defibrated straw obtained under a) to remove dust and other impurities amounting to at least 2%, and preferably 5% to 10%, of the defibrated straw by mass. The separation of undesirable residues, dust, or other materials affecting the performance of the insulating material can therefore be carried out by gravity using a sieve, for example a vibrating one, or by means of cyclonic filtration.

[0052] According to step b), the process consists of using cellulose wadding and performing a detangling and aeration of said cellulose wadding. This detangling and aeration phase of the cellulose wadding can be carried out separately in an ancillary installation or directly in mixer 3, before the introduction of the defibrated straw into said mixer 3.

[0053] According to step c), the process consists of mixing the defibrated straw under a) and the cellulose wadding prepared under b).

[0054] The cellulose wadding is therefore introduced into mixer 3, before the defibrated straw, for example by spraying, with a mass proportion between 1% and 30% relative to the total mass of the defibrated straw and the cellulose wadding.

[0055] According to step d), the process consists of injecting compressed air into the mixer 3 to homogenize the mixture and to obtain an insulating material with a density between 55 kg / m³ and 65 kg / m³. This is the density that must be achieved, for example, when blowing the bulk material into cavities.

[0056] The duration of the mixing operation depends on the size of mixer 3.

[0057] The process then consists, according to step e), of bagging the insulating material thus obtained and, where appropriate, palletizing it.

[0058] According to one example of implementation, the process consists of filtering the defibrated straw obtained under a) to remove dust and other impurities to a mass proportion of at least 2% and preferably 5% to 10% of the defibrated straw.

[0059] According to one example of implementation, the process consists of mixing cellulose wadding, or the cellulose wadding - defibrated straw mixture, with one or more adjuvants including a fungicide product, for example with a proportion by mass relative to the total mass of the mixture, of between 0.03% and 11% and preferably of between 0.5% and 4%.

[0060] For example, additives include at least one fire retardant with a proportion by mass relative to the total mass of the mixed products of between 10% and 30%. The precise proportion can be chosen according to the properties and performance required for the bulk material.

[0061] As an example, the fire retardant product, viscous or liquid, includes a geopolymer of the metakaolin type.

[0062] According to another example of implementation of the process, one or more adjuvants, fungicides and / or fire retardants can be mixed with the cellulose wadding prior to the mixing operation with the defibrated straw.

[0063] The invention also relates to a prefabricated modular wooden structure for constructing a partition or wall, or for cladding a wall of a building, on the exterior or interior side. Such a structure comprises at least one cavity containing the insulating material obtained according to the manufacturing process detailed above.

[0064] The invention also relates to a prefabricated modular structure made of mixed wood and concrete for constructing a partition or wall, or for cladding a wall of a building, on the exterior or interior side. Such a structure comprises at least one cavity containing the insulating material obtained according to the manufacturing process detailed above.

[0065] According to one implementation example, the cellulose wadding used is made entirely from recycled paper or from recycled paper incorporating recycled cardboard.

[0066] It is evident that the present description is not limited to the explicitly described examples, but also includes other modes of embodiment and implementation.

Claims

1. Method for continuously manufacturing a loose insulating material based on cereal straw, characterised in that it comprises the steps of: a) mechanically grinding the straw to obtain a defribed straw, the strands of which have an average length of between 3 mm and 22 mm, preferably between 3 mm and 11 mm, and an average diameter of between 0.5 mm and 4.0 mm, preferably between 0.5 and 2.5 mm, b) using cellulose wadding and untangling and aerating said cellulose wadding, c) using a mixer (3) and mixing the straw defibred in step a) and the cellulose wadding prepared in step b), said cellulose wadding being introduced into the mixer (3) before the defribed straw with a proportion by weight of between 1% and 30%, relative to the total weight of the defribed straw and the cellulose wadding, d) injecting compressed air into the mixer (3) to homogenise said mixture and to obtain a mixture having a density of between 55 kg / m3 and 65 kg / m3, and e) bagging the insulating material thus obtained.

2. Method according to claim 1, characterised in that it involves, in step a), using at least one grinder to shred and grind the straw in bales, said at least one grinder comprising shredding / grinding tools which can be adjusted to define the properties of the strands of obtained defribed straw in terms of shape and size, said tools comprising knives and hammers in sequence.

3. Method according to claim 1 or 2, characterised in that it involves, in step step c, in using at least one mixer (3) of the rotary cylinder and / or chute type.

4. Method according to any one of claims 1 to 3, characterised in that it involves filtering the defribed straw obtained in a) to remove dust and other impurities in a proportion by weight of at least 2%, preferably at least 5% to 10%, of the defribed straw.

5. Method according to any one of claims 1 to 4, characterised in that it involves mixing the cellulose wadding or the mixture of cellulose wadding and defribed straw, with one or more additives comprising a fungicidal product.

6. Method according to any one of claims 1 to 5, characterised in that it involves mixing the cellulose wadding or the mixture of cellulose wadding and defribed straw, with one or more additives comprising at least one fire-retardant product in a proportion by weight, relative to the total weight of the mixed products, of between 10% and 30%.

7. Method according to claim 6, characterised in that the fire-retardant product is selected from among products of a family of geo-based products.

8. Method according to claim 6, characterised in that the fire-retardant product is in viscous or liquid form and comprises a geopolymer of the metakaolin type.

9. Prefabricated modular structure made of wood or a mix of concrete and wood for producing a wall or for externally or internally covering a wall of a building, characterised in that it comprises at least one cavity containing the insulating material obtained in accordance with the method according to any of claims 1 to 8.

10. Prefabricated modular structure made of wood or a mix of concrete and wood for producing a wall or for externally or internally covering a wall of a building, characterised in that it comprises at least one cavity containing the insulating material obtained in accordance with the method according to any of claims 1 to 8.