Warm-keeping cotton as well as preparation method and application thereof

Abstract

The invention provides warm-keeping cotton and a preparation method and application thereof, and belongs to the technical field of warm-keeping cotton. The warm-keeping cotton is of a structure with at least two layers, the innermost layer comprises, by mass, 10%-30% of polyimide fibers and 70%-90% of aerogel fibers, and the outermost layer comprises, by mass, 40%-60% of polyimide fibers, 5%-10% of aramid fibers, 15%-50% of polyester fibers and 5%-15% of low-melting-point fibers. The composite structure design is adopted, the innermost layer is made of polyimide fibers and aerogel fibers in a specific proportion to achieve lightweight, skin-friendly and warm keeping, the outermost layer is made of polyimide fibers, aramid fibers, polyester fibers and low-melting-point fibers in a specific proportion to play a synergistic role, the heat preservation effect is further enhanced, and the flame retardant property is considered; therefore, the warm-keeping cotton with heat retaining property, light weight and flame retardance is obtained, the bottleneck in the prior art is broken through, and the application range is expanded.

Description

Technical Field

[0001] The present invention relates to the technical field of thermal insulation cotton, in particular to thermal insulation cotton and a preparation method and application thereof. Background Art

[0002] As the core filling material in clothing, bedding and industrial insulation, the performance of thermal cotton directly affects the thermal insulation effect and safety and reliability.

[0003] Current mainstream products (such as down, polyester hollow cotton, and ordinary synthetic cotton) face inherent bottlenecks in thermal insulation performance and safety risks due to their lack of flame retardancy. Traditional materials rely on a still air layer for insulation, but the fiber aggregate structure is susceptible to collapse under pressure (such as the compaction of wet down and repeated compression and deformation of synthetic cotton), which reduces the thickness of the air layer and dramatically increases the thermal conductivity. Especially in high humidity environments (such as sweating during outdoor exercise, rain, and snow), the thermal conductivity of the material can increase by 30%-50% after moisture absorption, resulting in significant heat loss. Furthermore, natural materials like down and cotton have a limiting oxygen index (LOI) of only 20%-22%, causing them to burn rapidly when exposed to open flames. Synthetic fibers (such as polyester) have an LOI of approximately 18%-20%, causing them to melt and drip at high temperatures, causing secondary burns. Such materials cannot meet flame retardancy standards for high-risk applications such as aviation and fire protection. Furthermore, existing technologies require increasing fill volume or loft to improve warmth, resulting in bulky and heavy finished products (for example, down jackets require a fill volume greater than 200g / m2). 2 In other words, current thermal insulation cotton can hardly meet the requirements of thermal insulation, lightweight and flame retardancy at the same time. Summary of the Invention

[0004] The present invention provides a thermal insulation cotton and a preparation method and application thereof, so as to solve the defects of the thermal insulation cotton in the prior art, such as insufficient thermal insulation effect and poor flame retardancy, thereby obtaining thermal insulation cotton that can be used in thermal insulation and flame retardant scenarios.

[0005] In the first aspect, the present invention provides a thermal cotton having at least two layers. With the layer closer to the user as the inner layer, the innermost layer comprises 10%-30% polyimide fiber and 70%-90% aerogel fiber, and the outermost layer comprises 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting-point fiber, in terms of mass percentage.

[0006] According to the thermal insulation cotton provided by the present invention, the denier of the polyimide fiber is 0.8D-5D, and the length is 32-64mm; the denier of the aramid fiber is 1.2D-3D, and the length is 32-64mm; the denier of the polyester fiber is 1.5D-7D, and the length is 32-74mm.

[0007] According to the thermal cotton provided by the present invention, in the innermost layer, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled therein; the outermost layer is formed by a non-woven process of 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting point fiber.

[0008] According to the thermal insulation cotton provided by the present invention, there are one or more intermediate layers between the innermost layer and the outermost layer, and the intermediate layers include polyimide fibers, polyester fibers and low-melting-point fibers. The content of the polyimide fibers increases from the innermost layer to the outermost layer.

[0009] According to the thermal insulation cotton provided by the present invention, the thickness of the innermost layer is 1-1.5 times the thickness of the outermost layer, and the gram weight of the thermal insulation cotton is 40g / m 2 -200g / m 2 .

[0010] According to the thermal insulation cotton provided by the present invention, the outer side of the innermost layer and / or the outermost layer is composited with a layer of non-woven fabric, the material of the non-woven fabric is polypropylene, polyethylene terephthalate or recycled polyethylene terephthalate; the gram weight of the non-woven fabric is 8g / m 2 -30g / m 2 .

[0011] The thermal insulation cotton provided by the present invention further comprises uniformly dispersed far-infrared ceramic powder, and the far-infrared ceramic powder is attached to the surface of the polyimide fiber.

[0012] In a second aspect, the present invention provides the use of the above-mentioned thermal insulation cotton in the preparation of textiles with thermal insulation and flame retardant effects.

[0013] In a third aspect, the present invention provides a method for preparing the above-mentioned thermal insulation cotton, comprising: First, a polyimide fiber mesh is prepared by electrospinning, and the obtained polyimide fiber mesh is immersed in an aerogel sol to prepare the innermost layer; The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed, and laid to form a multi-layer fiber web, and then baked to set the shape to prepare the middle layer and the outermost layer; The innermost layer is connected with the middle layer and the outermost layer through a nonwoven process.

[0014] In some embodiments of the present invention, in the baking and shaping step, the running speed of the fiber web in the oven is 3-4 m / min, the oven temperature is 135°C for the upper net, 140°C for the middle net, 145°C for the lower net, and the oven wind speed is 40-50 Hz.

[0015] Compared with the prior art, the present invention has the following beneficial effects: The present invention provides a thermal insulation cotton and its preparation method and application. By adopting a composite structure design, the innermost layer uses a specific proportion of polyimide fiber and aerogel fiber to achieve lightweight and skin-friendly warmth. The outermost layer uses a specific proportion of polyimide fiber, aramid fiber, polyester fiber and low-melting point fiber to work together to further enhance the thermal insulation effect while taking into account the flame retardant performance, thereby obtaining a thermal insulation cotton that is thermally insulating, lightweight and flame retardant, breaking through the bottleneck of existing technologies and expanding the scope of application. DETAILED DESCRIPTION

[0016] To make the objectives, technical solutions, and advantages of the present invention more clear, the technical solutions of the present invention are described clearly and completely below. Obviously, the embodiments described are only some of the embodiments of the present invention, not all of them. All other embodiments derived by persons of ordinary skill in the art based on the embodiments of the present invention without inventive effort are within the scope of protection of the present invention.

[0017] The endpoints of the ranges and any values disclosed herein are not limited to the precise ranges or values, and these ranges or values should be understood to include values close to these ranges or values. For numerical ranges, the endpoints of each range, the endpoints of each range and individual point values, and the individual point values can be combined with each other to obtain one or more new numerical ranges, which should be considered to be specifically disclosed herein.

[0018] In the description of this specification, the reference terms "one embodiment", "some embodiments", "specific implementation methods", or "some specific implementation methods" and the like mean that the specific features, structures, materials or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the embodiments of the present invention. In this specification, the schematic representations of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials or characteristics described can be combined in any one or more embodiments or examples in a suitable manner. In addition, those skilled in the art can combine and combine different embodiments or examples described in this specification and features of different embodiments or examples without contradiction.

[0019] If no specific techniques or conditions are specified in the examples, the experiments were carried out according to the techniques or conditions described in the literature in the field or according to the product instructions. If no manufacturer is specified for the reagents or instruments used, they are all conventional products that can be purchased through regular channels.

[0020] In the first aspect, the present invention provides a thermal cotton having at least two layers. With the layer closer to the user as the inner layer, the innermost layer comprises 10%-30% polyimide fiber and 70%-90% aerogel fiber, and the outermost layer comprises 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting-point fiber, in terms of mass percentage.

[0021] Polyimide fiber (PI fiber) is a high-performance, extreme-environment-resistant specialty synthetic fiber. It is made from polyimide polymer (a polymer containing imide rings in its backbone) through specialized spinning processes such as dry spinning, wet spinning, or electrospinning. PI fiber's core value lies in successfully transforming the exceptional heat resistance, chemical stability, and excellent mechanical and electrical properties of polyimide resin into fiber form, enabling its application in a wide range of extreme and harsh environments.

[0022] Aerogel fibers are new ultralight, high-porosity materials that incorporate the porous nanostructure of aerogel into a fibrous form. Main preparation methods include sol-gel with supercritical drying, thermally induced phase separation, biotemplating, and electrospinning with atmospheric pressure drying. The latter method is a novel, low-cost method that involves electrospinning nanofibers to form a 3D network, then impregnating them with an aerogel precursor, and finally drying them at atmospheric pressure.

[0023] Aramid fiber is a type of synthetic polyamide fiber with high strength, high modulus, and high temperature resistance, containing aromatic rings in the main chain. It is classified into para-aramid and meta-aramid. Meta-aramid is mainly used in the embodiments of the present invention.

[0024] The low-melting-point fiber described herein refers to a fiber whose cortex melts and forms a bonding agent when heated to a certain temperature (typically between 100°C and 150°C). This fiber exhibits excellent thermal bonding properties, blends easily with other fibers, and exhibits good elasticity. There are many types of low-melting-point fibers, common ones including low-melting-point polyester fibers, low-melting-point polyamide fibers, and low-melting-point polyester fibers. In some embodiments of the present invention, the low-melting-point fiber is low-melting-point polyester fiber.

[0025] The present invention adopts a composite structure design. The innermost layer uses a specific proportion of polyimide fiber and aerogel fiber to achieve lightweight and skin-friendly warmth. The outermost layer uses a specific proportion of polyimide fiber, aramid fiber, polyester fiber and low-melting point fiber to work together to further enhance the thermal insulation effect while taking into account the flame retardant performance, thereby obtaining a thermal insulation cotton that is thermally insulating, lightweight and flame retardant, breaking through the bottleneck of existing technologies and expanding the scope of application.

[0026] In some embodiments of the present invention, the polyimide fiber has a denier of 0.8D-5D and a length of 32-64 mm. Preferably, the polyimide fiber is a three-dimensional crimped polyimide fiber. Further preferably, the polyimide fiber used in the outermost layer has a denier of 0.8D-1.5D, which accounts for more than 80% of the total amount of the polyimide fiber in the outermost layer. Preferably, the polyimide fiber used in the innermost layer has a denier of 1D-3D.

[0027] In some embodiments of the present invention, the aramid fiber has a denier of 1.2D-3D and a length of 32-64 mm. The polyester fiber has a denier of 1.5D-7D and a length of 32-74 mm.

[0028] Fiber denier indicates its thickness. When 9,000 meters of fiber weigh 1 gram, its fineness is 1 denier (1D). The larger the denier, the thicker the fiber; the smaller the denier, the finer the fiber. Fiber denier affects its performance. For example, a lower denier is more likely to form a dense web, trapping more stagnant air layers and thus improving thermal insulation. However, a lower denier also results in lower bending stiffness and mechanical strength. Experimental studies have shown that selecting fibers within the above denier range can produce thermal insulation with superior overall performance.

[0029] In some embodiments of the present invention, in the innermost layer, the polyimide fibers form a three-dimensional skeleton network, and the aerogel fibers are filled therein.

[0030] In the above technical solution, the polyimide fibers in the innermost layer form a three-dimensional skeleton network, which can provide mechanical support and maximize the use of the rigidity and stability of the polyimide fibers to lock the air, thereby solving the problem that traditional thermal insulation cotton is easily compressed and collapsed; filling the formed three-dimensional skeleton network with aerogel fibers can fill the pores to achieve super insulation and obtain good thermal insulation effect.

[0031] In some embodiments of the present invention, the outermost layer is formed by a non-woven process of 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting point fiber.

[0032] The "nonwoven process" described in this invention refers to a material manufacturing technology that directly converts fibers into cloth, mesh, or flake-like structures without traditional spinning, weaving, or knitting processes. Its core steps are fiber web formation and web consolidation. The main fiber web formation methods include dry web formation (carding, air-laid), wet web formation, and spinning (such as spunbond and meltblown). The main web consolidation methods include mechanical bonding (needle punching, hydroentanglement), thermal bonding (hot calendering, hot air), and chemical bonding. In the examples of this invention, the outermost layer is primarily formed using carding and thermal bonding.

[0033] In some embodiments of the present invention, one or more intermediate layers are provided between the innermost and outermost layers, wherein the intermediate layers comprise polyimide fibers, polyester fibers, and low-melting-point fibers, with the polyimide fiber content increasing from the innermost layer to the outermost layer. Preferably, the intermediate layers comprise 20%-50% polyimide fibers, 20%-50% polyester fibers, and 10%-30% low-melting-point fibers.

[0034] The more middle layers are added, the better the thermal insulation effect is. However, this cannot be increased indefinitely, otherwise it will be detrimental to lightweighting. In practice, adding 1-3 middle layers is more appropriate. The present invention ensures that the content of polyimide fiber increases from the innermost layer to the outermost layer, which can effectively ensure that the inner layer is skin-friendly and the outer layer is flame-retardant, with good comprehensive performance.

[0035] In some embodiments of the present invention, the thickness of the innermost layer is 1-1.5 times the thickness of the outermost layer, and the weight of the thermal insulation cotton is 40g / m 2 -200g / m 2 The thermal insulation cotton of the present invention can effectively achieve lightweighting while ensuring warmth retention. When an intermediate layer is included, the thickness of the intermediate layer is preferably 0.6-1.1 times the thickness of the outermost layer.

[0036] In some embodiments of the present invention, a layer of non-woven fabric is compounded on the outside of the innermost layer and / or the outermost layer, and the material of the non-woven fabric is polypropylene, polyethylene terephthalate or recycled polyethylene terephthalate. Compounding a layer of non-woven fabric on the outside of the innermost layer and / or the outermost layer can better maintain the state of the thermal cotton after washing to avoid collapse and deformation. Among them, the outer side of the innermost layer refers to the side of the innermost layer away from the middle layer or the outermost layer, that is, the side close to the user; the outer side of the outermost layer refers to the side away from the user. In the above scheme, the compounding can adopt a non-woven process, such as a needle punching method. Optionally, the gram weight of the non-woven fabric is 8g / m 2 -30g / m 2 .

[0037] In order to further improve the function of the thermal insulation cotton, some specific functional materials can be added to the thermal insulation cotton of the present invention to achieve far infrared, antibacterial, antistatic and other functions.

[0038] For example, in some embodiments of the present invention, the thermal insulation cotton further comprises uniformly dispersed far-infrared ceramic powder, and the far-infrared ceramic powder is attached to the surface of the polyimide fiber.

[0039] In a second aspect, the present invention provides the use of the above-mentioned thermal insulation cotton in the preparation of textiles with thermal insulation and flame retardant effects.

[0040] In a third aspect, the present invention provides a method for preparing the above-mentioned thermal insulation cotton, comprising: First, a polyimide fiber mesh is prepared by electrospinning, and the obtained polyimide fiber mesh is immersed in an aerogel sol to prepare the innermost layer; The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed, and laid to form a multi-layer fiber web, and then baked to set the shape to prepare the middle layer and the outermost layer; The innermost layer is connected with the middle layer and the outermost layer through a nonwoven process.

[0041] In some embodiments of the present invention, the innermost layer may be connected to the middle layer and the outermost layer by needle punching.

[0042] It is understandable that when the thermal insulation cotton does not include an intermediate layer, the preparation method also does not include the preparation of the intermediate layer, and finally the innermost layer and the outermost layer are directly connected through a non-woven process.

[0043] In some embodiments of the present invention, in the baking and shaping step, the running speed of the fiber web in the oven is 3-4 m / min, the oven temperature is 135°C for the upper net, 140°C for the middle net, 145°C for the lower net, and the oven wind speed is 40-50 Hz.

[0044] The present invention uses a hot air method to consolidate the fiber web, resulting in a fluffy, soft, and pressure-free thermal insulation cotton. This method does not rely on roller pressure; instead, hot air penetrates the fiber web, melting the heat-melting component (low-melting-point fibers in this case). After cooling, bonding points are formed at the fiber intersections. Research by the present invention has found that the fiber web's speed in the oven (i.e., residence time), oven temperature, and air velocity must be controlled in a coordinated manner. If any of these parameters are not met, the resulting thermal insulation cotton's uniformity, bulk, and softness will be compromised, and a compromise in quality is achieved.

[0045] In order to facilitate understanding of the thermal insulation cotton and the preparation method thereof provided by the present invention, some specific examples are provided below for illustration.

[0046] In the following embodiments, the polyimide fiber used is a three-dimensional curled polyimide fiber, and the low-melting-point fiber used is a low-melting-point polyester fiber.

[0047] For the convenience of comparing performance, the weight of the thermal insulation cotton prepared in the following examples and comparative examples is 140g / m 2 .

[0048] Example 1 This embodiment provides a thermal insulation cotton having a two-layer structure. With the innermost layer being closer to the user, the innermost layer comprises, by mass percentage, 10% polyimide fiber and 90% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled in the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64 mm. The outermost layer is formed by a non-woven process of 40% polyimide fiber, 5% aramid fiber, 50% polyester fiber and 5% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 80% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0049] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The outermost fiber raw materials are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven. The oven temperature is 135°C for the upper mesh, 140°C for the middle mesh, and 145°C for the lower mesh. The oven wind speed is 45 Hz to prepare the outermost layer. The thickness of the outermost layer is the same as that of the innermost layer. 4) Connect the innermost layer and the outermost layer by acupuncture; 5) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0050] Example 2 This embodiment provides a thermal insulation cotton having a two-layer structure. With the innermost layer being closer to the user, the innermost layer comprises, by mass percentage, 30% polyimide fiber and 70% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled in the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64 mm. The outermost layer is formed by a non-woven process of 60% polyimide fiber, 10% aramid fiber, 15% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0051] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The outermost fiber raw materials are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven. The oven temperature is 135°C for the upper net, 140°C for the middle net, and 145°C for the lower net. The oven wind speed is 45 Hz to prepare the outermost layer. The thickness of the innermost layer is 1.5 times the thickness of the outermost layer. 4) Connect the innermost layer and the outermost layer by acupuncture; 5) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0052] Example 3 This embodiment provides a thermal insulation cotton having a two-layer structure. With the innermost layer being closer to the user, the innermost layer comprises, by mass percentage, 20% polyimide fiber and 80% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled in the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64 mm. The outermost layer is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0053] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The outermost fiber raw materials are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven. The oven temperature is 135°C for the upper mesh, 140°C for the middle mesh, and 145°C for the lower mesh. The oven wind speed is 45 Hz to prepare the outermost layer. The thickness of the outermost layer is the same as that of the innermost layer. 4) Connect the innermost layer and the outermost layer by acupuncture; 5) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0054] Example 4 This embodiment provides a thermal insulation cotton having a three-layer structure. With the innermost layer being closer to the user, the innermost layer comprises, by mass percentage, 20% polyimide fiber and 80% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled in the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64 mm. The middle layer is formed by a non-woven process of 35% polyimide fiber, 45% polyester fiber and 20% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm. The outermost layer is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0055] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven. The oven temperatures are 135°C for the upper net, 140°C for the middle net, and 145°C for the lower net. The oven wind speed is 45 Hz. The middle layer and the outermost layer are prepared. The thickness of the outermost layer is the same as that of the innermost layer, and the thickness of the middle layer is 0.8 times that of the outermost layer. 4) Connect the innermost layer to the baked and consolidated middle layer and outermost layer by needle puncture; 5) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0056] Example 5 This embodiment provides a thermal insulation cotton having a three-layer structure. With the innermost layer being closer to the user, the innermost layer comprises, by mass percentage, 20% polyimide fiber and 80% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber is filled in the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64 mm. The middle layer is formed by a non-woven process of 35% polyimide fiber, 45% polyester fiber and 20% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm. The outermost layer is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0057] The outermost layer is also compounded with a layer of polypropylene non-woven fabric, the weight of the non-woven fabric is 10g / m 2 .

[0058] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven. The oven temperatures are 135°C for the upper mesh, 140°C for the middle mesh, and 145°C for the lower mesh. The air speed is 45 Hz. The middle layer and the outermost layer are prepared. The outermost layer, the middle layer, and the innermost layer have the same thickness. 4) Connect the innermost layer to the baked and consolidated middle layer and outermost layer by needle puncture; 5) Needle punch a layer of polypropylene non-woven fabric on the outer side of the outermost layer; 6) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0059] Example 6 This embodiment provides a thermal insulation cotton having a two-layer structure, with the innermost layer being closer to the user and the innermost layer being formed by a non-woven process of 20% polyimide fiber and 80% aerogel fiber, in terms of mass percentage, wherein the polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm; The outermost layer is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber, wherein the denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, the denier of the aramid fiber is 1.2D-3D and the length is 32-64mm, and the denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0060] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, which is specifically as follows: 1) Mix, loosen, comb and lay the innermost fiber raw materials to form a multi-layer fiber web; 2) Mixing, opening, combing and laying the outermost fiber raw materials to form a multi-layer fiber web; 3) The fiber webs from steps 1) and 2) are stacked and placed in an oven for baking and shaping. The fiber webs are run in the oven at a speed of 3.5 m / min, with the oven temperatures of 135°C for the upper web, 140°C for the middle web, and 145°C for the lower web, and the oven air speed is 45 Hz to prepare a cured fiber web. The thickness of the outermost layer is the same as the thickness of the innermost layer. 4) The surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0061] Comparative Example 1 This comparative example provides a common thermal insulation cotton, which is composed of 100% polyester and has a single-layer structure.

[0062] Comparative Example 2 This comparative example provides pure down for comparison.

[0063] Comparative Example 3 This comparative example provides a thermal insulation cotton with a single-layer structure. The three-dimensional skeleton network is formed by polyimide fibers, and aerogel fibers are filled in the three-dimensional skeleton network. The polyimide fibers have a denier of 1D-3D and a length of 32-64 mm.

[0064] The preparation method comprises the following steps: preparing a polyimide fiber mesh by electrostatic spinning, impregnating the obtained polyimide fiber mesh in an aerogel sol, and drying the mesh at normal pressure to prepare the thermal insulation cotton.

[0065] Comparative Example 4 This comparative example provides a thermal cotton with a single-layer structure, which is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D, and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of the polyimide fiber in the outermost layer, the denier of the aramid fiber is 1.2D-3D, the length is 32-64mm, and the denier of the polyester fiber is 1.5D-7D, and the length is 32-74mm.

[0066] Its preparation method is: The fiber raw materials are mixed, loosened, carded, and laid in a staggered manner to form a multi-layer fiber web; the fiber web is sent into an oven for baking and shaping. The running speed of the fiber web in the oven is 3.5 m / min, the oven temperature is 135°C for the upper net, 140°C for the middle net, 145°C for the lower net, and the oven wind speed is 45 Hz to prepare warm cotton.

[0067] Comparative Example 5 This comparative example provides a thermal insulation cotton having a two-layer structure, with the innermost layer being closer to the user and being formed by a non-woven process of 35% polyimide fiber, 45% polyester fiber, and 20% low-melting-point fiber, by weight percentage. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm, and the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm. The outermost layer is formed by a non-woven process of 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low-melting point fiber. The denier of the polyimide fiber is 0.8D-5D and the length is 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of polyimide fiber in the outermost layer. The denier of the aramid fiber is 1.2D-3D and the length is 32-64mm. The denier of the polyester fiber is 1.5D-7D and the length is 32-74mm.

[0068] Its preparation method is: 1) The fiber raw materials of the innermost layer and the outermost layer are mixed, opened, combed and laid respectively, and the laying is staggered laying to form a multi-layer fiber web; 2) The fiber web is placed in an oven for baking and shaping. The fiber web is run in the oven at a speed of 3.5 m / min. The oven temperature is 135°C for the upper net, 140°C for the middle net, and 145°C for the lower net. The oven wind speed is 45 Hz to prepare a thermal insulation cotton. The thickness of the outermost layer is the same as the thickness of the innermost layer. 3) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0069] Comparative Example 6 This comparative example provides a thermal insulation cotton, the structure and components of which are the same as those of Example 3, and the preparation method thereof is as follows: 1) preparing a polyimide fiber mesh by electrospinning, impregnating the obtained polyimide fiber mesh into an aerogel sol, and drying at normal pressure to prepare an innermost layer; 2) The outermost fiber raw materials are mixed, opened, combed, and laid in a staggered manner to form a multi-layer fiber web; 3) The fiber web is sent into an oven for baking and shaping. The fiber web runs in the oven at a speed of 4.5 m / min, an oven temperature of 140°C, and an oven wind speed of 55 Hz to prepare the outermost layer. The thickness of the outermost layer is the same as that of the innermost layer. 4) Connect the innermost layer and the outermost layer by acupuncture; 5) Finally, the thermal insulation cotton is surface-treated and cut into rolls to obtain the finished product.

[0070] Performance Testing Test method: The test standard for fabric thermal resistance and Kroger value is GB / T 11048-2008; fabric thermal resistance and Kroger value represent warmth retention, and the higher the value, the better.

[0071] The testing standards for bulk, compression, and recovery are in Appendix A of FZ / T64003-2021. Bulk is a measure of the volume occupied by a unit mass of thermal insulation. It directly reflects the insulation's looseness and air-holding capacity. A higher value indicates a larger volume, looser structure, and higher air content for the same weight. Compression measures the degree to which the insulation shrinks under external force, directly reflecting its bulky structure's ability to withstand pressure and its spatial compression efficiency. Recovery indicates the quilt's ability to recover after compression; higher values are better.

[0072] The Limiting Oxygen Index (LOI) test standard is ASTM D2863; it measures the minimum oxygen concentration required for a material to sustain combustion in a nitrogen-oxygen mixture. LOI ≥ 28% indicates self-extinguishing properties, and LOI > 35% indicates a flame-retardant material.

[0073] Durability: The retention of warmth (Kroger value) after 20 washes.

[0074] The test results are shown in Table 1.

[0075] Table 1

[0076] From the above results, it can be seen that the embodiments of the present invention adopt a composite structure design, and the innermost layer uses a specific proportion of polyimide fiber and aerogel fiber to achieve lightweight and skin-friendly warmth. The outermost layer uses a specific proportion of polyimide fiber, aramid fiber, polyester fiber and low-melting point fiber to work together to further enhance the thermal insulation effect and take into account the flame retardant performance, thereby obtaining a thermal insulation cotton that is both thermally insulating, lightweight and flame retardant. Among them, Example 4 is provided with an additional middle layer, which has a better thermal insulation effect. Example 5 is further compounded with a layer of non-woven fabric on the outside of the outermost layer to increase the durability of the thermal insulation cotton. Comparative Examples 1-5 are compared with the embodiments to fully illustrate the importance of the structure and composition of the thermal insulation cotton of the present invention. During the preparation process of Comparative Example 6, the three parameters of the running speed of the fiber web in the oven, namely the residence time, oven temperature and oven wind speed, were not controlled in a coordinated manner, so that the resulting thermal insulation cotton could not take into account uniformity, fluffiness and softness.

[0077] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit it. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that they can still modify the technical solutions described in the aforementioned embodiments, or make equivalent replacements for some of the technical features therein. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims

1. A thermal insulation cotton, characterized in that: It has at least two-layer structure. With the layer closest to the user as the innermost layer, by mass percentage, the innermost layer includes 10%-30% polyimide fiber and 70%-90% aerogel fiber, and the outermost layer includes 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting point fiber.

2. The thermal insulation cotton according to claim 1, characterized in that: The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm; the aramid fiber has a denier of 1.2D-3D and a length of 32-64mm; the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm.

3. The thermal insulation cotton according to claim 1, characterized in that: In the innermost layer, the polyimide fibers form a three-dimensional skeleton network, and the aerogel fibers are filled therein; The outermost layer is formed by a non-woven process with 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low-melting-point fiber.

4. The thermal insulation cotton according to claim 1, characterized in that: One or more intermediate layers are provided between the innermost layer and the outermost layer. The intermediate layers include polyimide fibers, polyester fibers and low-melting-point fibers. The content of the polyimide fibers increases from the innermost layer to the outermost layer.

5. The thermal insulation cotton according to any one of claims 1 to 4, characterized in that: The thickness of the innermost layer is 1-1.5 times the thickness of the outermost layer, and the weight of the thermal insulation cotton is 40g / m 2 -200g / m 2 .

6. The thermal insulation cotton according to any one of claims 1 to 4, characterized in that: The outer side of the innermost layer and / or the outermost layer is composited with a layer of non-woven fabric, the material of the non-woven fabric is polypropylene, polyethylene terephthalate or recycled polyethylene terephthalate, and the gram weight of the non-woven fabric is 8g / m 2 -30g / m 2 .

7. The thermal insulation cotton according to any one of claims 1 to 4, characterized in that: The invention also comprises uniformly dispersed far-infrared ceramic powder, which is attached to the surface of the polyimide fiber.

8. Use of the thermal insulation cotton according to any one of claims 1 to 7 in the preparation of textiles with thermal insulation and flame retardant effects.

9. The method for preparing the thermal insulation cotton according to any one of claims 1 to 7, characterized in that: include: First, a polyimide fiber mesh is prepared by electrospinning, and the obtained polyimide fiber mesh is immersed in an aerogel sol to prepare the innermost layer; The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed, and laid to form a multi-layer fiber web, and then baked to set the shape to prepare the middle layer and the outermost layer; The innermost layer is connected with the middle layer and the outermost layer through a nonwoven process.

10. The method for preparing the thermal insulation cotton according to claim 9, characterized in that: In the baking and shaping step, the running speed of the fiber web in the oven is 3-4 m / min, the oven temperature is 135° C. for the upper net, 140° C. for the middle net, 145° C. for the lower net, and the oven wind speed is 40-50 Hz.

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