Preparation method of waste textile flame-retardant aerogel

Abstract

The invention discloses a preparation method of waste textile flame-retardant aerogel. The preparation method comprises the steps of cleaning and crushing, biological enzyme treatment, low-temperature freezing, ultraviolet irradiation, liquid nitrogen drying and the like. The preparation method comprises the following steps: cleaning, crushing, treating with biological enzyme, mixing with sodium hydroxide / urea, freezing at low temperature, unfreezing at room temperature, adding a photosensitive cross-linking agent, and performing ultraviolet irradiation; cleaning the hydrogel to neutral pH, and treating the hydrogel with liquid nitrogen for 10-20 hours to obtain an aerogel base material; after the aerogel is cut, the outer layer is dip-coated with a flame retardant solution, the inner layer is dip-coated with a composite solution of a reinforcing agent and carbon dioxide, a skin-core structure with an eccentric cross section is formed, and the aerogel with excellent flame retardance is prepared through vacuum drying and curing; a skin layer solution containing a flame retardant and a core layer solution of a composite solution are introduced in S5, a skin-core structure with eccentric cross section layout is formed in S6, and excellent flame retardant performance is shown, so that when the aerogel encounters flames, flame propagation can be delayed, and the heat release rate can be reduced.

Description

Technical Field

[0001] The invention relates to the technical field of waste textile aerogels, and in particular to a method for preparing a gas-resistant aerogel made of waste textiles. Background Art

[0002] With the growth of textile consumption, the problem of waste textile disposal is becoming increasingly serious. Traditional disposal methods such as landfill or incineration not only cause environmental pollution, but also lead to waste of resources. Therefore, research on the recycling of waste textiles has great value potential in the sustainable development of the chemical economy and the high added value utilization of solid waste.

[0003] Aerogel is a special gel obtained by replacing the liquid in hydrogel with gas, with high porosity and large specific surface area. It is currently recognized as the world's lowest density solid material and is considered one of the most promising thermal insulation materials due to its excellent thermal insulation properties.

[0004] Due to its abundant internal pores and good thermal insulation properties, aerogels have shown application potential in many fields such as adsorption materials, environmental purification, energy storage, sensor materials, catalysis, automobile manufacturing, spacecraft, electronic equipment, clothing, thermal insulation, and sound insulation.

[0005] Waste textile aerogels are easily ignited, which limits their application in the flame retardant field. Therefore, flame retardant modification of waste textile aerogels is crucial to expand their application areas.

[0006] Therefore, it is necessary to provide a method for preparing a flame-retardant gas gel from waste textiles to solve the above technical problems. Summary of the invention

[0007] The invention overcomes the shortcomings of the prior art and provides a method for preparing a flame-retardant gas gel from waste textiles.

[0008] To achieve the above object, the technical solution adopted by the present invention is: a method for preparing fire-resistant gas gel from waste textiles, comprising the following steps:

[0009] S1. Use clean water and neutral detergent to clean the waste textiles, crush the cleaned textiles into 1-5 mm fiber fragments by mechanical means, and treat them with 1-2% of the weight of the textiles using biological enzymes;

[0010] S2, mixing the pretreated fiber fragments with a sodium hydroxide / urea alkali system solution, freezing them at low temperature, and then thawing them at room temperature;

[0011] S3, adding a photosensitive cross-linking agent to the thawed mixture, and exposing the mixture to ultraviolet light for irradiation;

[0012] S4, washing the mixture after ultraviolet irradiation until the pH value of the hydrogel sample reaches neutral, using liquid nitrogen for 10-20 hours to obtain waste textile-based aerogel;

[0013] S5, cutting the hydrogel sample into a desired shape to prepare a skin layer solution and a core layer solution;

[0014] S6, forming a skin-core structure, dipping the outer layer in the skin layer solution to form a flame-retardant skin layer, and dipping the inner layer in the core layer solution to form a reinforced core layer;

[0015] S7. The soaked skin-core structure is dried using a vacuum drying technique, and the curing enhancer is heated for curing.

[0016] In a preferred embodiment of the present invention, in S1, the cleaning time ranges from 15 to 60 minutes, the particle size of the fiber fragments is 1 to 5 mm, and the biological enzyme treatment time is 1 to 4 hours.

[0017] In a preferred embodiment of the present invention, in S2, the pretreated fiber fragments are mixed with a sodium hydroxide / urea alkali system solution at a mass ratio of 1:5-1:10, and are frozen for 3-6 hours at a low temperature of -10--18°C, and the thawing time ranges from 1 to 2 hours.

[0018] In a preferred embodiment of the present invention, in S3, the amount of the photosensitive crosslinking agent is 0.5-2% of the dry weight of the hydrogel, the ultraviolet irradiation time is in the range of 0.5-1.5h, and the ultraviolet intensity is in the range of 100-400μW / cm2.

[0019] In a preferred embodiment of the present invention, in S5, the skin layer solution is a flame retardant solution, and the core layer solution is a composite solution of a reinforcing agent solution and carbon dioxide.

[0020] In a preferred embodiment of the present invention, the method for preparing the composite solution is: adding an enhancer solution into a reaction kettle, and introducing carbon dioxide gas to form the composite solution.

[0021] In a preferred embodiment of the present invention, the pressure range of the reactor is controlled at 1-5 bar and the temperature is controlled at 50-80°C.

[0022] In a preferred embodiment of the present invention, in S6, the dipping time of the outer layer and the inner layer of the skin-core structure is in the range of 5-15 hours.

[0023] In a preferred embodiment of the present invention, in S7, the drying time ranges from 20 to 30 hours, the curing time ranges from 5 to 10 hours, and the curing temperature ranges from 50 to 150°C.

[0024] In a preferred embodiment of the present invention, in S6, the skin-core structure has an eccentric cross-sectional layout, and the distribution of the skin layer and the core layer in the skin-core structure presents an eccentric shape.

[0025] The present invention solves the defects existing in the background technology and has the following beneficial effects:

[0026] (1) The present invention provides a method for preparing a flame-retardant gel from waste textiles. By washing, crushing and treating waste textiles with biological enzymes, high-value utilization of waste is achieved, and environmental pollution and resource waste are reduced. The use of biological enzymes not only improves the processability of fibers, but also reduces the use of chemical treatment agents, which is in line with the principles of green chemistry.

[0027] (2) The present invention provides a method for preparing a flame-retardant gas aerogel from waste textiles. By introducing a skin solution containing a flame retardant and a core solution of a composite solution in step S5, and forming a skin-core structure with an eccentric cross-sectional layout in step S6, the aerogel of the present invention exhibits excellent flame retardant properties; when the aerogel encounters a flame, it can effectively delay the spread of flame and reduce the heat release rate.

[0028] (3) The present invention provides a method for preparing a flame-retardant gas aerogel from waste textiles, which not only has excellent flame retardant properties, but also provides enhanced mechanical strength and durability through a unique skin-core structure design. The eccentric cross-sectional layout brings additional structural advantages to the material, such as improved thermal insulation and acoustic properties; in addition, by controlling the preparation conditions of the composite solution, such as pressure and temperature, the pore structure and chemical composition of the aerogel can be customized to meet the needs of specific applications. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art are briefly introduced below. Obviously, the drawings described below are only some embodiments recorded in the present invention. For those of ordinary skill in the art, other drawings can be obtained based on these drawings without creative work.

[0030] Figure 1 It is a schematic diagram of a flow chart of a preferred embodiment of the present invention;

[0031] Figure 2 It is a schematic cross-sectional view of an eccentric skin-core structure of a preferred embodiment of the present invention. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] In the following description, many specific details are set forth to facilitate a full understanding of the present invention, but the present invention may also be implemented in other ways different from those described herein. Therefore, the protection scope of the present invention is not limited to the specific embodiments disclosed below.

[0034] In the description of the present application, it should be understood that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present application and simplifying the description, rather than indicating or implying that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as limiting the scope of protection of the present application. In addition, the terms "first", "second", etc. are only used for descriptive purposes, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Therefore, features defined as "first", "second", etc. may explicitly or implicitly include one or more of the features. In the description of the invention, unless otherwise specified, "multiple" means two or more.

[0035] In the description of this application, it should be noted that, unless otherwise clearly specified and limited, the terms "installed", "connected", and "connected" should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral connection; it can be a mechanical connection or an electrical connection; it can be directly connected or indirectly connected through an intermediate medium, and it can be the internal communication of two components. For ordinary technicians in this field, the specific meanings of the above terms in this application can be understood by specific circumstances.

[0036] like Figure 1-Figure 2 As shown, the present invention provides a method for preparing a flame-retardant gas gel from waste textiles, comprising the following steps:

[0037] S1. Use clean water and neutral detergent to clean the waste textiles for a period of 15-60 minutes, mechanically crush the cleaned textiles into fiber fragments of 1-5 mm, and use a biological enzyme accounting for 1-2% of the weight of the textiles for treatment for 1-4 hours;

[0038] S2, mixing the pretreated fiber fragments with a sodium hydroxide / urea alkali system solution at a mass ratio of 1:5-1:10, freezing the mixture at a low temperature of -10-18°C for 3-6 hours, and then thawing the mixture at room temperature for 1-2 hours;

[0039] S3, adding a photosensitive crosslinker to the thawed mixture, wherein the amount of the photosensitive crosslinker is 0.5-2% of the dry weight of the hydrogel, and exposing the mixture to ultraviolet light for irradiation, wherein the ultraviolet light irradiation time ranges from 0.5 to 1.5 hours, and the ultraviolet light intensity ranges from 100 to 400 μW / cm2;

[0040] S4, washing the mixture after ultraviolet irradiation until the pH value of the hydrogel sample reaches neutral, using liquid nitrogen for 10-20 hours to obtain waste textile-based aerogel;

[0041] S5, cutting the hydrogel sample into a desired shape, preparing a skin layer solution, the skin layer solution is a flame retardant solution, preparing a core layer solution, the core layer solution is a composite solution of a reinforcing agent solution and carbon dioxide;

[0042] The composite solution preparation method is as follows: adding an enhancer solution into a reaction kettle, then introducing carbon dioxide gas, and controlling the pressure range to be 1-5 bar and the temperature to be 50-80° C., so that the carbon dioxide and the enhancer solution are fully contacted and dissolved to form a composite solution;

[0043] S6, forming a skin-core structure, dipping the outer layer in the skin solution to form a flame-retardant skin, and dipping the inner layer in the core solution to form a reinforced core, the dipping time range of the outer layer and the inner layer of the skin-core structure is 5-15 hours, the skin-core structure has an eccentric cross-sectional layout, and the distribution of the skin and core layers in the skin-core structure presents an eccentric shape;

[0044] S7. The soaked skin-core structure is dried using vacuum drying technology, with a drying time ranging from 20 to 30 hours, and the curing enhancer is heated for curing, with a curing time of 5 to 10 hours and a curing temperature of 50 to 150°C.

[0045] It should be noted that:

[0046] In the S1 stage, the fiber surface is cleaned through washing and bio-enzyme treatment, laying the foundation for subsequent crushing and processing; the freezing and thawing treatment in S2 helps to further purify and adjust the fiber structure, making it more uniform and creating conditions for subsequent steps; in the S3 stage, the use of photosensitive cross-linking agents and ultraviolet irradiation enhance the bonding force between fibers, providing a stable foundation for the preparation of aerogels.

[0047] Entering S4, after cleaning and removing excess chemicals, liquid nitrogen treatment quickly cools and solidifies the fiber structure to form an aerogel with high porosity and low density, showing excellent thermal insulation and sound insulation properties; in the S5 stage, through cutting and preparation of composite solutions, not only the shape and size of the aerogel are customized, but also flame retardant and reinforcing properties are given. The carbon dioxide in the composite solution has flame retardant properties, and its use in the composite solution further enhances the flame retardant effect of the final aerogel product; in S6, the dip-coating process forms a composite structure with a flame retardant outer layer and a reinforcing inner layer, which improves the versatility of the material and enhances the mechanical strength and durability.

[0048] In S6, Figure 2 The skin-core aerogel with an eccentric structure design shows significant performance advantages in many aspects. First, the local mechanical strength of the material is significantly enhanced, especially when facing uneven loads, which can provide better support and resistance; second, the eccentric distribution of the flame-retardant skin layer strategically covers the flammable area of ​​the material, thereby improving the overall flame retardant performance at key points; in addition, the uneven distribution of the skin and core layer also optimizes the thermal insulation performance, forming a more effective thermal insulation layer in specific areas and enhancing the thermal insulation effect.

[0049] Finally, in the S7 stage, vacuum drying technology removes moisture and avoids thermal damage, while heating and curing the reinforcing agent improves the final strength and stability of the material. The entire process not only increases the added value of waste textiles, but also produces new aerogel materials with multiple properties.

[0050] Embodiment 1:

[0051] S1: Soak the waste textiles in clean water and wash them with a neutral detergent for 30 minutes; after washing, use a mechanical crusher to crush the textiles into fiber fragments of 3 mm in size; add 1.5% by weight of biological enzymes to the fiber fragments and treat them in a constant temperature water bath for 2 hours.

[0052] S2: The pretreated fiber fragments were mixed with a sodium hydroxide / urea alkali system solution at a mass ratio of 1:8, and the mixture was frozen at a low temperature of -15°C for 4 hours, and then thawed at room temperature for 1 hour.

[0053] S3: Add 1% of the dry weight of the hydrogel to the thawed mixture with a photosensitive crosslinker; expose the mixture to a UV box with an irradiation time of 1 h and an UV intensity of 200 μW / cm 2 .

[0054] S4: The mixture after step S3 is thoroughly washed with deionized water until the pH value reaches neutral; the washed hydrogel sample is treated in liquid nitrogen for 15 hours to form a waste textile-based aerogel.

[0055] S5: Cut the aerogel sample into the size of 100 mm x 100 mm x 10 mm.

[0056] Preparation of skin layer solution: Use 10% trichloroethyl phosphate as the flame retardant solution.

[0057] Preparation of core layer solution: 5% ammonium polyphosphate reinforcing agent solution was heated to 65° C. in a reaction kettle, and carbon dioxide gas at a pressure of 3 bar was introduced for 1 hour to form a composite solution.

[0058] S6: Forming a skin-core structure:

[0059] The outer layer of the aerogel was dipped into the skin solution for 10 h to form a flame retardant skin.

[0060] The inner layer was dip-coated in the core layer solution for 10 h to form a reinforced core layer.

[0061] S7: Use a vacuum drying oven to dry the skin-core structure after step S6, and the drying time is set to 25 hours.

[0062] After drying, the samples were placed in an oven and cured at 100 °C for 7.5 h to enhance the final cure of the agent.

[0063] Comparative Example 1:

[0064] The comparative example 1 is substantially the same as the embodiment 1, except that in step S1, the waste textiles are cleaned with clean water and a neutral detergent, and the cleaned textiles are mechanically crushed into fiber fragments of 1-5 mm.

[0065] Comparative Example 2:

[0066] The second comparative example is the same as the step S1 of the first comparative example, except that: no steps S2 to S7 are performed, that is, no freezing treatment, photosensitive crosslinking agent treatment, cleaning, liquid nitrogen treatment, cutting, composite solution preparation, dip coating, drying and curing are performed, and fiber fragments that have been basically cleaned and treated with biological enzymes are obtained, but no aerogel structure is formed.

[0067] Comparative Example 3:

[0068] The comparative example 3 is basically the same as the embodiment 1, except that in step S5, when preparing the skin layer solution and the core layer solution, no flame retardant or reinforcing agent is added, and only the basic solution is used.

[0069] Experiment 1:

[0070] Comparing the flame retardant effects of Example 1 with Comparative Examples 1, 2 and 3, samples of the same mass were taken:

[0071] Vertical combustion test: All samples were subjected to vertical combustion test, and parameters such as burning time, flame propagation speed, and carbonization length were recorded;

[0072] Oxygen Index (OI) Test: The oxygen index of each sample is measured to assess the oxygen concentration required for combustion.

[0073] Cone calorimeter test: The heat release rate (HRR), smoke production rate (SPR) and total smoke production of the sample are tested using a cone calorimeter;

[0074] Microstructure analysis: The microstructure of the samples after combustion was observed by scanning electron microscopy (SEM);

[0075] Mechanical properties test: test the tensile strength and elongation at break of samples to evaluate mechanical properties;

[0076] Thermal insulation performance test: evaluate the thermal insulation performance of the sample, such as thermal conductivity;

[0077] Table 1:

[0078]

[0079]

[0080] According to Table 1:

[0081] Vertical burning time: Example 1 shows the shortest burning time (23.48 seconds), which is significantly lower than Comparative Example 1 (58.14 seconds), Comparative Example 2 (117.82 seconds) and Comparative Example 3 (51.37 seconds), which indicates that Example 1 has faster self-extinguishing ability and outstanding flame retardant performance.

[0082] Oxygen Index (OI): Example 1 has the highest oxygen index (29.34%), which means that compared with the comparative example, Example 1 is more difficult to ignite and maintain combustion in air.

[0083] Heat release rate (HRR): Example 1 has the lowest HRR value (21.02 kW / m 2 ), which indicates that it releases the least heat during combustion and has excellent flame retardant properties.

[0084] Smoke generation rate (SPR): The SPR value of Example 1 is the lowest (0.05m 2 / s), which means it produces the least smoke when burned, helping to reduce visibility problems and toxicity risks during fires.

[0085] Tensile strength: Example 1 has the highest tensile strength (5.59 MPa), which indicates that it has good mechanical strength, which may be attributed to its unique skin-core structure and the use of reinforcing agents.

[0086] Elongation at break: Example 1 has the highest elongation at break (15.82%), which indicates that it has good flexibility and ductility, which helps to improve the durability and reliability of the material.

[0087] Thermal conductivity: Example 1 has the lowest thermal conductivity (0.02 W / m·K), which indicates that it has the best thermal insulation performance, which is very important for scenarios requiring thermal insulation applications.

[0088] The above is based on the ideal embodiment of the present invention. Through the above description, relevant personnel can make various changes and modifications without departing from the technical concept of the present invention. The technical scope of the present invention is not limited to the content in the specification, and the technical scope must be determined according to the scope of the claims.

Claims

1. A method for preparing a flame-retardant gel from waste textiles, characterized in that: The following steps are involved: S1. Use clean water and neutral detergent to clean the waste textiles, crush the cleaned textiles into 1-5 mm fiber fragments by mechanical means, and treat them with 1-2% of the weight of the textiles using biological enzymes; S2, mixing the pretreated fiber fragments with a sodium hydroxide / urea alkali system solution, freezing them at low temperature, and then thawing them at room temperature; S3, adding a photosensitive cross-linking agent to the thawed mixture, and exposing the mixture to ultraviolet light for irradiation; S4, washing the mixture after ultraviolet irradiation until the pH value of the hydrogel sample reaches neutral, using liquid nitrogen for 10-20 hours to obtain waste textile-based aerogel; S5, cutting the hydrogel sample into a desired shape to prepare a skin layer solution and a core layer solution; S6, forming a skin-core structure, dipping the outer layer in the skin layer solution to form a flame-retardant skin layer, and dipping the inner layer in the core layer solution to form a reinforced core layer; S7. The soaked skin-core structure is dried using a vacuum drying technique, and the curing enhancer is heated for curing.

2. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In the S1, the cleaning time ranges from 15 to 60 minutes, the particle size of the fiber fragments is 1 to 5 mm, and the biological enzyme treatment time is 1 to 4 hours.

3. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In the S2, the pretreated fiber fragments are mixed with a sodium hydroxide / urea alkali system solution at a mass ratio of 1:5-1:10, and are frozen for 3-6 hours at a low temperature of -10--18°C, with a thawing time ranging from 1 to 2 hours.

4. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In the S3, the amount of the photosensitive crosslinking agent is 0.5-2% of the dry weight of the hydrogel, the ultraviolet irradiation time is in the range of 0.5-1.5h, and the ultraviolet intensity is in the range of 100-400μW / cm2.

5. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In the step S5, the skin layer solution is a flame retardant solution, and the core layer solution is a composite solution of a reinforcing agent solution and carbon dioxide.

6. The method for preparing a flame-retardant gel from waste textiles according to claim 5, characterized in that: The composite solution preparation method comprises: adding an enhancer solution into a reaction kettle, and introducing carbon dioxide gas to form the composite solution.

7. The method for preparing a flame-retardant gel from waste textiles according to claim 6, characterized in that: The reactor pressure range is controlled at 1-5 bar and the temperature is controlled at 50-80°C.

8. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In S6, the dipping time of the outer layer and the inner layer of the skin-core structure is in the range of 5-15 hours.

9. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In S7, the drying time ranges from 20 to 30 hours, the curing time ranges from 5 to 10 hours, and the curing temperature ranges from 50 to 150°C.

10. The method for preparing a flame-retardant gel from waste textiles according to claim 1, characterized in that: In the S6, the skin-core structure has an eccentric cross-sectional layout, and the distribution of the skin layer and the core layer in the skin-core structure presents an eccentric shape.

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