Procedure for obtaining an insulating panel for construction from textile waste and insulating panel obtained with the same

Abstract

The present invention discloses a process for obtaining an insulating panel for construction from textile waste, involving the steps of shredding textile waste, preparing a binding solution from a boron salt and a complex carbohydrate, and mixing it with the shredded textile waste; pouring the resulting mass into a mold, pressing, and drying. The invention also discloses the resulting insulating panel, which has a thermal conductivity of between 0.079 and 0.095 W / (mK), is a self-extinguishing material, and has a weighted sound absorption coefficient of 0.55, making it a material with noteworthy properties suitable for construction applications.

Description

Procedure for obtaining an insulating panel for construction from textile waste and insulating panel obtained with the same OBJECT OF THE INVENTION The present invention relates to a process for obtaining an insulating panel for construction using textile waste, thus generating a sustainable insulating panel with remarkable fireproof, acoustic, thermal and antifungal properties that offer an ecological and high-performance alternative to known insulators. On the other hand, the sustainable insulating panel obtained by the developed procedure is also an object of the invention, which has a percentage of at least 75% textile waste in the dry insulating panel obtained, and a thermal conductivity of between 0.079 and 0.095 W / (mK). It should also be noted that the sum of boron salt and complex carbohydrate should not exceed 25% in the resulting dry insulating panel. BACKGROUND OF THE INVENTION These are well-known insulating materials used in construction made with synthetic foams, mineral fibers or petroleum derivatives, which have a high environmental impact in their production and final disposal. On the other hand, the textile industry generates large amounts of waste that mostly end up in landfills without proper treatment. Therefore, it is concluded that in the field of construction materials there is a significant need arising from society's demand to incorporate sustainable materials that, while being effective in their insulating action, are made up of waste generated by humans, such as textile waste. In particular, document EP4048844A1 discloses a process that initially involves shredding textile waste to obtain a homogeneous textile fiber; followed by the preparation of a binding solution from casein; mixing this binding solution with the homogeneous textile fiber, where the mixture is moist and the homogeneous textile fiber is present in a percentage of between 45% and 60% relative to the binding solution; subsequently pouring the mass resulting from the previous step into a mold; pressing the mass for compaction; and finally drying the compacted mass at room temperature. However, this document does not disclose essential aspects of the present invention, such as the use of an alkaline binder based on a boron salt and a complex carbohydrate, its preparation at a temperature between 50°C and 90°C, or the fact that the drying is carried out at a high temperature (between 60°C and 90°C). Thus, the applicant of this patent identifies the need to provide a procedure that allows obtaining a sustainable building material that offers performance that meets the required needs and that, using textile waste as the main raw material, allows proposing an ecological binder and a panel with excellent insulating and fire-resistant properties. DESCRIPTION OF THE INVENTION The present invention proposes a procedure for obtaining an insulating panel for construction from textile waste, the insulating panel obtained using the developed procedure also being the object of the invention. The object of the present invention is to use textile waste, mainly that which comes from the textile industry, in such a way that it can be used to obtain an insulating panel. Specifically, the textile waste involved in the process of obtaining the insulating panel of the present invention is very specific, essentially containing remnants from garments, scraps and unused fibers. In other words, the proposed procedure allows for the use of these textile waste materials that would otherwise go to landfill. The procedure of the invention comprises the following operational steps: - Crushing of textile waste until a homogeneous textile fiber is obtained. - Preparation of a binding solution which is an alkaline aqueous solution with a pH between 8 and 11 in which a boron salt and a complex carbohydrate are combined under agitation at a temperature between 50 and 90 ºC. - Mixing the binding solution with the homogeneous textile fiber in a mixer, where the mixture is wet and the homogeneous textile fiber is present in a percentage between 45 and 60% (preferably 52%) with respect to the binding solution. - Pouring the resulting mass from the previous stage into a mold. - Pressing the mass for compaction, which can be done cold or hot. - Drying the compacted mass at a temperature between 60 and 90 ºC until an insulating panel with a moisture content of less than 10% is achieved. Preferably, the boron salt used in the preparation of the binding solution is borax or boric acid, while the complex carbohydrate is modified starch or cellulose. It should also be noted that, optionally, in the process of the invention, a sealant is applied after drying. In another embodiment of the process of the invention, and also optionally, a sealant, or a dye or varnish, preferably environmentally friendly, is applied after drying. Thus, the invention procedure allows the obtaining of a sustainable insulating panel that has been characterized to determine its fire resistance, thermal insulation and fungal insulation capacity. In this sense, the described procedure yields an insulating panel that has a percentage of at least 75% textile waste in the dry insulating panel obtained, and a thermal conductivity of between 0.079 and 0.095 W / (mK), a very advantageous behavior as concluded from the tests shown in the preferred embodiment section. Similarly, it should be noted that the sum of boron salt and complex carbohydrate should not exceed 25% in the resulting dry insulating panel. Likewise, it should be noted that the insulating panel obtained is a self-extinguishing material class HBF as established in the ASTM D4986-20 standard, which has a Weighted Sound Absorption coefficient of 0.55 as established in the ISO 11654:1997 standard, classified with an acoustic absorption class D and has a noise reduction coefficient of 0.52 as established in the ASTM C42.- 09a standard, with an average sound absorption of 0.50. All these parameters have been tested and obtained as explained in the following preferred embodiment of the invention section. Therefore, the present invention provides a solution to the problem related to the processing and obtaining of insulating panels for sustainable construction by including textile waste from the industry in its composition. It should be noted that, optionally, the textile waste includes fibers of different colors, creating a heterogeneous visual pattern in the resulting insulating panel. Advantageously, the surface of the insulating panel can be left exposed in interior applications, functioning as an abstract decorative element without requiring additional coatings and constituting a unique design for use in spaces where an exposed finish is desired. Among the suitable applications for the insulating panel obtained according to the present invention, the following should be noted: - Interior coverings (walls, ceilings) as acoustic-thermal insulation and decorative element. - Modular partitions in offices or residential spaces. - Passive fire protection in metal structures, wood or electrical installations. - Structural partitions (walls) as an insulating core. Optionally, a natural or synthetic sealant can be applied to the insulating panel to improve its moisture resistance without affecting its aesthetic appearance. The insulating panel of the invention can also be treated with eco-friendly dyes or varnishes to adjust its color without compromising its fire-retardant properties. In other words, various treatments can be applied to the insulating panel to increase its adaptability to different environments. In short, the invention is presented as a high value-added technological option in technical and environmental terms, since the insulating panels developed with the textile waste are biodegradable and maintain fire resistance and acoustic absorption and noise reduction performance as expected. BRIEF DESCRIPTION OF THE DRAWINGS To complement the description that follows and to aid in a better understanding of the characteristics of the invention, according to a preferred embodiment thereof, a set of figures is included as an integral part of said description, in which, for illustrative and non-limiting purposes, the following has been represented: Figure 1 shows four photographs of the test specimens of the insulating panel subject to the invention, tested according to the details in Test 1. Figure 2 shows the graph of results from test 1 where the x-axis represents the frequency (expressed in Hz) and the y-axis represents the equivalent absorption area per unit. Figure 3 shows a graph with the results of test 1, where the x-axis corresponds to the frequency (Hz) and the y-axis represents the sound absorption coefficient (p). Figure 4 shows a schematic of the thermal conductivity equipment used in test 2. Figure 5.- Corresponds to a graph of test 2, where the test temperature, temperature differential obtained and applied voltage over time are shown. Figure 6.- Corresponds to a graph of test 2, where the thermal conductivity obtained over time is shown. Figure 7 shows four photographs of the test specimen subject to the invention taken during test 3. Figure 8 shows the diagram of the test chamber used in test 3. PREFERRED EMBODIMENT OF THE INVENTION A preferred embodiment of the procedure for obtaining an insulating panel for construction from textile waste according to the present invention is detailed below: - Shredding of textile waste: Textile waste (garments, scraps, unused fibers) is fed into an industrial shredder to reduce its size and obtain a homogeneous textile fiber. This homogeneous textile fiber will serve as structural reinforcement and provide insulating properties to the final product. - Preparation of the binding solution: In a stirred reactor, an alkaline aqueous solution (pH between 8 and 11) is prepared in which the following are combined: • A boron salt (e.g., borax or boric acid), which confers fire-retardant and antifungal properties. • A complex carbohydrate (such as modified starch or cellulose), which acts as a natural binder. The mixture formed by boron salt and a carbohydrate is heated to a moderate temperature (between 50 °C and 90 °C) under constant stirring until a homogeneous solution is obtained, which we call the agglomerating solution. - Mixed: The homogeneous textile fiber obtained in the first stage described above is introduced into an industrial mixer, where it is blended with the previously prepared binding solution until a uniform mass is formed. The resulting mixture is moist, and the homogeneous textile fiber is present in the mixture at a percentage of between 45 and 60% relative to the binding solution. While it is true that the proportion of textile fiber and binding solution may vary depending on the desired density of the insulating panel to be obtained. - Pressed The mass resulting from the previous stage is poured into a mold and subjected to pressing, either cold or hot, to compact the material. - Drying The compact mass that has been pressed is subjected to drying, for this purpose it is taken to an industrial dryer (oven or drying chamber) at a temperature between 60 and 90 °C until the insulating panel obtained reaches a moisture content of less than 10%, and a percentage of at least 75% textile waste in the dry insulating panel obtained. The properties of the resulting insulating panel are detailed below: - High fire resistance (due to the presence of boron salts). - Acoustic insulation (due to the fibrous structure of the recycled textile). - Thermal insulation (low thermal conductivity). - Antifungal and antibacterial properties. - Low environmental impact (uses textile waste and natural binders). Of particular interest are the advantages associated with the insulating panel of the invention: - Sustainability: Reuses textile waste, reducing its environmental impact. - Safety: Greater fire resistance than conventional insulation. - Energy efficiency: Better thermal and acoustic insulation. - Low cost: Low cost raw material as it comes from waste. TEST 1: SOUND ABSORPTION OF MATERIALS In test 1, sound absorption is performed for a test specimen or sample according to the insulating panel obtained from the procedure of the present invention. Testing facilities Sound absorption tests are conducted in the reverberation chamber of the Acoustics Laboratory at the Center for Research, Development, and Innovation in Structures and Materials of the University of Chile (IDIEM), located at Plaza Ercilla 883, Santiago, Chile. In the testing facility, the internal surfaces of the perimeter walls are not parallel, nor is the ceiling parallel to the floor. These walls are made of concrete, 40 cm thick, and are mechanically disconnected with an elastomeric material. The chamber has a volume of 252.0 m³ and a total surface area of ​​approximately 243.1 m². Test procedure The sound absorption of the specimen was determined using the interrupted response method. For this purpose, the room was excited with pink noise generated by a CESVA omnidirectional source, model BP012, and the sound pressure level decays were measured inside the empty reverberation chamber and subsequently with the specimen placed inside. In both situations, the decays were measured using two source positions, 12 fixed microphone positions randomly distributed within the room, and one decay per microphone position. In all measurements, the signal-to-noise ratio was greater than 15 dB. Equipment Table 1 specifies the characteristics of the equipment used for measuring sound absorption as detailed above. Table 1: Characteristics of the equipment used for measuring sound absorption. In Table 1, NS corresponds to the Serial Number and when referring to "Class" the codes used correspond to: Class "1": the equipment complies with IEC 61672-1:2002 standard Class "-": the equipment does NOT comply with an IEC 61672-1:2002 standard Description of the tested element Table 2 specifies the characteristics of the tested insulating panel specimen or sample. Table 2: Specifications of the tested insulating panel specimen. Figure 1 shows four photographs of the test specimens of the insulating panel of the invention used in the sound absorption test. Measurement and environmental conditions Table 3 specifies the measurement and environmental conditions of the enclosure with and without a test tube or sample. Table 3: Relative humidity and temperature (°C) of the room with and without the sample. Results of the sound absorption test of materials Tables 5 and 6 show the results obtained in the sound absorption coefficient test of the tested insulating panel specimen. Table 5: Results obtained in the absorption coefficient test which are represented in figure 2. Table 6: Results obtained in the absorption coefficient test, which correspond to the sound absorption coefficient (p) data represented in figure 3. It should be noted that in Figure 3 the continuous line with diamonds corresponds to the practical sound absorption coefficient (p) of the test specimen (values ​​collected in Table 6), the thick gray line shows the reference sound absorption coefficient or the sound absorption standard curve defined by ISO 11654 to compare against the measured material, and the continuous line represents the difference between the practical sound absorption coefficient (p) and the reference curve established by ISO 11654, a value obtained that is below the reference value obtained from ISO 11654. The solid line with diamonds corresponds to the practical sound absorption coefficient (p) in octave bands, even though Table 6 expresses these values ​​in third-octave bands. This complies with ISO 11654, whereby the values ​​are obtained by converting thirds to octaves using the arithmetic mean. Table 7 presents the results of the acoustic evaluation of the insulating panel according to the ISO 11654 and ASTM C423 standards for the insulating panel. Table 7: Results of the acoustic evaluation of the insulating panel, where the weighted sound absorption coefficient (aw), acoustic absorption class, noise reduction coefficient (NRC) and sound absorption average (SAA) are represented. Table 8 shows the classification of the sound absorption of the insulating panel specimen or sample according to the weighted coefficient (w) value. This classification ranges from class A (maximum absorption) to the "No Classification" category. Table 8: Acoustic absorption class of the insulating panel specimen. From test 1 we conclude that the analyzed specimen of the insulating panel of the invention presents an acoustic absorption of 0.55 as established in the ISO 11654:1997 standard, classified as a class of acoustic absorption D. TEST 2: THERMAL CONDUCTIVITY COEFFICIENT In test 2, the thermal conductivity coefficient is measured for a test specimen or sample conforming to the insulating panel obtained from the procedure of the present invention. Description of the insulating panel test specimen Table 9 presents the description of the insulating panel sample to be tested. Table 9: Description of the test specimen or sample of insulating panel. Preparation of the insulating panel test specimen Table 10 shows the information relating to the preparation of the insulating panel test specimen. Table 10: Information relating to the preparation of the test specimen or sample of insulating panel. Essay description The thermal conductivity coefficient was determined in accordance with the provisions of standard NCh850.Of2008 "Thermal insulation - Determination of thermal resistance in steady state and related properties - Guard hot plate apparatus". For this purpose, the test specimens were installed horizontally and symmetrically with respect to the flat electric heater of the equipment. Steady-state conditions were achieved with a stabilized power supply and thermostatic temperature control. Temperature measurements were taken using thermocouples. The interior of the equipment was filled with polystyrene beads to minimize heat loss through the outer edges of the guard section and the test specimens. Figure 4 shows the schematic of the thermal conductivity equipment used in test 2, identifying: the central measuring heater (1), the hot guard plate (2), the test material specimens (3), and the cold plates (4). It should be noted that the specimens are arranged on an inner and an upper plane. Trial results Table 11 shows the results obtained in the thermal conductivity test of the insulating panel. Table 11: Thermal conductivity test results. Figure 5 shows the test temperature, the temperature difference obtained (average temperature change), and the voltage applied over time for each tested specimen. The right y-axis represents the voltage (expressed in V), the left y-axis represents the temperature (expressed in °C), and the x-axis corresponds to the time elapsed during the test (expressed in hours:minutes:seconds format). Four temperature measurements were taken: two for the specimen in a higher position and two for the specimen in a lower position. This graph shows the results for the solid line with "x" (a) lower specimen 1, gray line with "+" (b) upper specimen 1, gray line with "o" (c) upper specimen 2, black line with transparent triangles "" (d) lower specimen 2, gray line with transparent rhombuses "" (e) average Delta temperature. The black line with opaque black circle "" (f) corresponds to volts. On the other hand, Figure 6 shows the thermal conductivity obtained for the tested specimens over time. The y-axis represents the thermal conductivity (expressed in W / (mK)) and the x-axis indicates the time elapsed during the test (expressed in hours:minutes:seconds format). Observations: The test was carried out entirely in accordance with standard NCh850.Of2008. TEST 3: FLAME BEHAVIOR In test 3, the flame behavior of test specimens or samples is analyzed according to the insulating panel obtained from the procedure of the present invention. Scope and field of application The test results show the self-extinguishing capacity of the aforementioned samples, tested under the ASTM D4986-20 standard "Standard Test Method for Horizontal Burning Characteristics of Cellular Polymeric Materials", and according to the SII-PP-305 V.06 procedure, in the IDIEM Fire Laboratory located at Salomón Sack 840, Cerrillos (Chile). Rehearsal Ten identical specimens or samples measuring 150 mm x 50 mm x 13 mm were prepared. Five of them (1 to 5) were conditioned for 48 hours at a temperature of 23 ± 2 °C and a relative humidity of 50 ± 5%. The remaining five specimens (6 to 10) were conditioned for 168 hours in an oven at 70 ± 5 °C. These latter specimens were cooled in a desiccator at room temperature. Each test specimen was marked at 25 mm, 60 mm, and 125 mm at one end and placed horizontally on a steel grid. Cotton was placed under the grid. Combustion was then initiated at one end using a special fan-flame burner, applied for 60 seconds. The initial, final, and flameless combustion times, as well as the length burned, were measured. Classification: Materials classified as HBF (Horizontal Burning Foam) - materials that meet the following criteria were classified as HBF: - Materials classified as HBF must not have any test specimen that has a burning rate greater than 40 mm / min in a 100 mm section or must not have any test specimen where combustion has reached the 125 mm mark. If only one test specimen or sample from a set of samples does not meet this classification, then the test must be repeated with five other test specimens conditioned in the same way. - All specimens in this second group must meet the same requirements (thickness and density) for the material to be classified as HBF. Materials classified as HF1 and HF2 (Horizontal Flame) must comply with Table 12. Table 12 shows the classification of HF1 and HF2 materials. Table 12. Classification of HF1 and HF2 materials Where: a) 4 / 5 - Four out of five test tubes b) 1 / 5 - One out of five test tubes c) If the upper and lower sides of the test specimen show different extents of damage, the side with greater damage should be chosen to determine its classification. According to the results obtained, the test specimens or samples are classified as follows: a) Self-extinguishing material class HF1. b) Self-extinguishing material class HF2. c) Self-extinguishing material class HBF. d) Easily combustible material. Terminology - Self-extinguishing: Material that, being combustible, goes out after the ignition source that has combusted it ceases to act upon it. - Flame combustion time (Lcll): Time elapsed from when the standardized flame is removed from the test specimen, until the moment when the flame combustion is extinguished. - Flameless combustion time (Lsll): Time elapsed from the end of the flameless combustion time in the test specimen until the end of the flameless combustion. In the case of test specimens that continue to burn without a flame, it is the time that this type of combustion (incandescent combustion) lasts. - Burned Length (L): This is the maximum length affected by combustion, measured in millimeters. - Combustion Rate (CR): This is the speed at which the flame advances from the 25 mm mark to the 125 mm mark. It is only calculated for combustible materials. - M25 Time: The time it takes for combustion to reach the 25 mm mark. - M60 Time: Time at which combustion reaches the 60 mm mark. - M125 Time: Time at which combustion reaches the 125 mm mark. Results The flame behavior results obtained for the insulating panel are valid only for the tested insulating panel specimen. This can be observed in Figure 7 as the received specimen (Figure 7A), the specimen during the test (Figure 7B), the specimen after the flame was removed (Figure 7C), and the specimen at the end of the test (Figure 7D). Table 13 details the average characteristics of the 10 insulating panel specimens tested. Table 13. Average characteristics of the tested insulating panel specimens. Table 14 contains the results of the flame behavior test for specimens 1 to 5. Table 14. Results of the flame behavior test for specimens 1 to 5. Table 15 contains the results of the flame behavior test for specimens 6 to 10. Table 15. Results of the flame behavior test for specimens 6 to 10. Table 16 shows the average results of the flame behavior test for specimens 1 to 10. Table 16. Average results of the flame behavior test for specimens 1 to 10. Table 17 shows the average air velocity (expressed in m / s) in a test chamber as shown in Figure 8. Table 17. Air velocity values ​​in the air chamber. According to the results obtained from test 3, the specimen or sample is a self-extinguishing material class HBF, as established in the ASTM D4986-20 standard. - The 10 test tubes self-extinguish once the standard flame is removed. - None of the test specimens reach the 25 mm mark. - No test specimen reaches the 125 mm mark. - There wasn't much smoke production and very little smell. Therefore, from the three tests carried out with test specimens or samples according to the insulating panel obtained by the procedure of the present invention, we conclude that: - They have a thermal conductivity of 0.087 W / (mK). - It is a self-extinguishing material class HBF as established in the ASTM D4986-20 standard. - It has a Weighted Sound Absorption coefficient of 0.55 as established in the ISO 11654:1997 standard, classified with an acoustic absorption class D. - It presents a noise reduction coefficient of 0.52 as established in the ASTM C42.- 09a standard, with an average sound absorption of 0.50.

Claims

1. A method for obtaining an insulating panel for construction from textile waste, characterized in that it comprises the following steps: - Shredding the textile waste until a homogeneous textile fiber is obtained. - Preparation of an alkaline aqueous binding solution with a pH between 8 and 11, in which a boron salt and a complex carbohydrate are combined under agitation at a temperature between 50 and 90 °C. - Mixing the binding solution with the homogeneous textile fiber in a mixer, where the mixture is moist and the homogeneous textile fiber is present in a percentage of between 45 and 60% with respect to the binding solution. - Pouring the mass resulting from the previous step into a mold. - Pressing the mass for compaction. - Drying the compacted mass at a temperature between 60 and 90 °C until an insulating panel with a moisture content of less than 10% is obtained. 2.A process for obtaining an insulating panel for construction from textile waste, according to claim 1, characterized in that the boron salt is borax or boric acid.

3. A process for obtaining an insulating panel for construction from textile waste, according to claim 1, characterized in that the complex carbohydrate is modified starch or cellulose.

4. A process for obtaining an insulating panel for construction from textile waste, according to claim 1, characterized in that the pressing of the mass is carried out cold or hot.

5. A process for obtaining an insulating panel for construction from textile waste, according to claim 1, characterized in that a sealant is applied after drying.

6. A process for obtaining an insulating panel for construction from textile waste, according to claim 1, characterized in that a dye or varnish is applied after drying. 7.Insulating panel obtained from the process of any of the preceding claims, characterized in that it contains 75% dry textile waste.

8. Insulating panel, according to claim 7, characterized in that it has a sealant layer.

9. Insulating panel, according to claim 7, characterized in that it has a dye or varnish layer.

10. Insulating panel, according to claim 7, characterized in that it has a thermal conductivity of between 0.079 W / (mK) and 0.095 W / (mK).

11. Insulating panel, according to claim 7, characterized in that it is a self-extinguishing material, class HBF, as established in ASTM D4986-20.

12. Insulating panel, according to claim 7, characterized in that it has a Weighted Sound Absorption coefficient of 0.55 as established in ISO 11654:1997, classified with an acoustic absorption class D 13.Insulating panel, according to claim 7, characterized in that it has a noise reduction coefficient of 0.52 as established in the ASTM C42.- 09 standard, with an average sound absorption of 0.50.

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