Thermal cotton, and preparation method and application thereof

Abstract

The application provides a warm cotton and a preparation method and application thereof, and belongs to the technical field of warm cottons. The warm cotton has at least two layers of structures, and the innermost layer comprises 10-30% polyimide fibers and 70-90% aerogel fibers in terms of mass percentage, and the outermost layer comprises 40-60% polyimide fibers, 5-10% aramid fibers, 15-50% polyester fibers and 5-15% low-melting-point fibers. The application adopts a composite structure design, the specific proportion of polyimide fibers and aerogel fibers is selected for the innermost layer to realize lightweight and skin-friendly warmth, the specific proportion of polyimide fibers, aramid fibers, polyester fibers and low-melting-point fibers is selected for the outermost layer to synergistically play a role, the warmth-keeping effect is further enhanced, and the flame-retardant performance is considered, so that a warm cotton with warmth-keeping, lightweight and flame-retardant properties is obtained, the bottleneck of the prior art is broken, and the application range is expanded.

Description

Technical Field

[0001] This invention relates to the field of thermal insulation cotton technology, and in particular to a thermal insulation cotton, its preparation method, and its application. Background Technology

[0002] As a core filling material in clothing, bedding, and industrial insulation, thermal insulation cotton's performance directly affects its heat insulation effect and safety reliability.

[0003] Currently, mainstream products (such as down, polyester hollow fiber, and ordinary synthetic fiber cotton) suffer from inherent limitations in insulation performance and safety hazards due to a lack of flame retardant properties. Traditional materials rely on a static air layer for insulation, but the fibrous aggregate structure is prone to collapse under pressure (such as down hardening when wet or synthetic fiber cotton undergoing repeated compression and deformation), resulting in a reduced air layer thickness and a sharp increase in thermal conductivity. Especially in high humidity environments (such as outdoor exercise with sweating or rain and snow), the thermal conductivity of the material can increase by 30%-50% after absorbing moisture, causing serious heat loss. Moreover, natural materials such as down and cotton have a limiting oxygen index (LOI) of only 20%-22%, igniting rapidly when exposed to open flames; synthetic fibers (such as polyester) have an LOI of about 18%-20%, melting and dripping at high temperatures, causing secondary burns. Such materials cannot meet the flame retardant standards of high-risk fields such as aviation and fire fighting. In addition, current technologies require increasing the filling weight or loft to improve warmth, resulting in a heavy finished product (e.g., down jackets require a filling weight >200g / m²). 2 (Only then can it meet the requirement of -10℃ insulation), which violates the lightweight requirements of modern equipment. In other words, current thermal insulation materials can hardly meet the requirements of insulation, lightweight, and flame retardancy. Summary of the Invention

[0004] This invention provides a thermal insulation cotton, its preparation method, and its application, in order to solve the defects of insufficient thermal insulation effect and poor flame retardancy of existing thermal insulation cotton, thereby obtaining thermal insulation cotton that can be applied to thermal insulation and flame retardant scenarios.

[0005] In a first aspect, the present invention provides a thermal insulation cotton having at least two layers, with the innermost layer being closer to the user, comprising, by weight percentage, 10%-30% polyimide fiber and 70%-90% aerogel fiber, and the outermost layer comprising 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low melting point fiber.

[0006] According to the thermal insulation cotton provided by the present invention, 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; and the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm.

[0007] According to the thermal insulation cotton provided by the present invention, 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 nonwoven process from 40%-60% polyimide fibers, 5%-10% aramid fibers, 15%-50% polyester fibers and 5%-15% low melting point fibers.

[0008] According to the thermal insulation cotton provided by the present invention, there is one or more intermediate layers between the innermost layer and the outermost layer, the intermediate layers comprising polyimide fibers, polyester fibers and low melting point fibers, wherein the content of 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 weight of the thermal insulation cotton is 40 g / m². 2 -200g / m 2 .

[0010] According to the thermal insulation cotton provided by the present invention, a non-woven fabric is laminated to the innermost layer and / or the outermost layer, wherein the non-woven fabric is made of polypropylene, polyethylene terephthalate, or recycled polyethylene terephthalate; and the basis weight of the non-woven fabric is 8 g / m². 2 -30g / m 2 .

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

[0012] Secondly, the present invention provides the application of the above-mentioned thermal insulation cotton in the preparation of textiles with heat-insulating and flame-retardant properties.

[0013] Thirdly, the present invention provides a method for preparing the above-mentioned thermal insulation cotton, comprising:

[0014] First, a polyimide fiber web is prepared by electrospinning. The obtained polyimide fiber web is then impregnated in an aerogel sol to prepare the innermost layer.

[0015] The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed and laid into a web to form a multi-layer fiber web. After baking and shaping, the middle layer and the outermost layer are obtained.

[0016] The innermost layer is connected to the middle and outermost layers using a nonwoven process.

[0017] In some embodiments of the present invention, during the baking and shaping step, the fiber web runs at a speed of 3-4 m / min in the oven, the oven temperature is 135°C for the upper web, 140°C for the middle web, and 145°C for the lower web, and the oven wind speed is 40-50 Hz.

[0018] Compared with the prior art, the present invention has the following beneficial effects:

[0019] This invention provides a thermal insulation cotton, its preparation method, and its application. By adopting a composite structure design, the innermost layer uses a specific ratio of polyimide fiber and aerogel fiber to achieve lightweight and skin-friendly warmth, while the outermost layer uses a specific ratio of polyimide fiber, aramid fiber, polyester fiber, and low-melting-point fiber to work synergistically, further enhancing the thermal insulation effect and taking into account flame retardant properties. This results in a thermal insulation cotton that combines thermal insulation, lightweight, and flame retardancy, breaking through the existing technical bottlenecks and expanding the application range. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of this invention clearer, the technical solutions of this invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this invention, not all embodiments. Based on the embodiments of this invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of this invention.

[0021] The endpoints and any values ​​of the ranges 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 endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed herein.

[0022] In the description of this specification, the references to terms such as "one embodiment," "some embodiments," "specific implementation," or "some specific implementations," etc., refer to specific features, structures, materials, or characteristics described in connection with that embodiment or example, which are included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples. Moreover, without contradiction, those skilled in the art can combine and integrate the different embodiments or examples described in this specification, as well as the features of different embodiments or examples.

[0023] Where specific techniques or conditions are not specified in the examples, they shall be performed in accordance with the techniques or conditions described in the literature in this field, or in accordance with the product instructions. Reagents or instruments whose manufacturers are not specified are all conventional products that can be purchased through legitimate channels.

[0024] In a first aspect, the present invention provides a thermal insulation cotton having at least two layers, with the innermost layer being closer to the user, comprising, by weight percentage, 10%-30% polyimide fiber and 70%-90% aerogel fiber, and the outermost layer comprising 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low melting point fiber.

[0025] Polyimide fiber (PI fiber) is a high-performance, extreme-environment-resistant specialty synthetic fiber. It is made from polyimide polymer (a polymer with imide rings in its main chain) through special spinning processes (such as dry spinning, wet spinning, or electrospinning). Its core value lies in successfully transforming the excellent heat resistance, chemical stability, and superior mechanical and electrical properties of polyimide resin into a fiber form, enabling its application in numerous extreme and harsh environments.

[0026] Aerogel fibers are novel ultralight, high-porosity materials that endow the porous nanostructure of aerogels with a fibrous morphology. The mainstream preparation methods include sol-gel + supercritical drying, thermally induced phase separation, biotemplating, and electrospinning + atmospheric pressure drying. Among these, electrospinning + atmospheric pressure drying is a novel, low-cost preparation method. The specific steps involve first electrospinning nanofibers to form a 3D network, then impregnating the aerogel precursor, and finally drying at atmospheric pressure.

[0027] Aramid fibers are a type of high-strength, high-modulus, and high-temperature-resistant synthetic polyamide fiber whose main chain contains aromatic rings. They are classified into para-aramid and meta-aramid, and the embodiments of this invention mainly use meta-aramid.

[0028] The low-melting-point fiber described in this invention refers to a fiber whose outer layer melts and bonds when heated to a certain temperature (typically between 100°C and 150°C). This type of fiber exhibits excellent thermal bonding properties, is easily mixed with other fibers, and possesses good elasticity. There are many types of low-melting-point fibers, commonly including low-melting-point polyester fibers, low-melting-point polyamide fibers, and low-melting-point polyester fibers. In some embodiments of this invention, the low-melting-point fiber is low-melting-point polyester fiber.

[0029] This invention employs a composite structure design. The innermost layer uses a specific ratio of polyimide fiber and aerogel fiber to achieve lightweight and skin-friendly warmth. The outermost layer uses a specific ratio of polyimide fiber, aramid fiber, polyester fiber, and low-melting-point fiber to work synergistically, further enhancing the heat insulation effect while also taking into account flame retardant properties. This results in a warm cotton that combines heat insulation, lightweight, and flame retardancy, breaking through existing technical bottlenecks and expanding its application range.

[0030] In some embodiments of the present invention, the polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Preferably, the polyimide fiber is a three-dimensional crimped polyimide fiber. More preferably, the polyimide fiber used in the outermost layer has a denier of 0.8D-1.5D, accounting for more than 80% of the total amount of polyimide fiber in the outermost layer. Preferably, the polyimide fiber used in the innermost layer has a denier of 1D-3D.

[0031] In some embodiments of the present invention, 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.

[0032] Denier indicates the fineness of a fiber. One denier (1D) is defined as the weight of 9000 meters of fiber that is 1 gram. A higher denier indicates a thicker fiber, while a lower denier indicates a finer fiber. Denier affects fiber performance; for example, a lower denier makes it easier to form a dense web, trapping more still air and thus providing better insulation. However, a lower denier also results in lower fiber bending stiffness and weaker mechanical strength. Experiments have shown that using fibers within the aforementioned denier range yields thermal insulation materials with superior overall performance.

[0033] In some embodiments of the present invention, in the innermost layer, the polyimide fibers form a three-dimensional skeletal network, and the aerogel fibers are filled therein.

[0034] In the above technical solution, the innermost layer of polyimide fibers forms a three-dimensional skeleton network, which can provide mechanical support and maximize the use of the rigidity and stability of polyimide fibers to lock in air, thereby solving the problem of traditional thermal insulation cotton being easily compressed and collapsed; the aerogel fibers filled in the formed three-dimensional skeleton network can fill the pores to achieve super insulation and obtain a good heat preservation effect.

[0035] In some embodiments of the present invention, the outermost layer is formed by a nonwoven process from 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low melting point fiber.

[0036] The "nonwoven process" described in this invention is a material manufacturing technology that directly forms fibers into fabric, web, or wadding structures without traditional spinning, weaving, or knitting processes. Its core steps are fiber web formation and web consolidation. The main methods for fiber web formation include dry web formation (carding, air-jet forming), wet web formation, and spinning web formation (such as spunbond and meltblown processes). The main methods for web consolidation include mechanical consolidation (needle punching, hydroentangling), thermal bonding consolidation (hot rolling, hot air bonding), and chemical bonding consolidation. In the embodiments of this invention, the outermost layer mainly employs carding and thermal bonding consolidation.

[0037] In some embodiments of the present invention, one or more intermediate layers are further provided between the innermost and outermost layers. These intermediate layers comprise polyimide fibers, polyester fibers, and low-melting-point fibers, with the content of the polyimide fibers increasing from the innermost to the outermost layer. Preferably, the intermediate layer comprises 20%-50% polyimide fibers, 20%-50% polyester fibers, and 10%-30% low-melting-point fibers.

[0038] Adding more intermediate layers improves insulation, but there's no limit to the number; otherwise, it hinders weight reduction. Adding 1-3 intermediate layers is generally suitable. This invention ensures that the polyimide fiber content increases progressively from the innermost to the outermost layer, effectively guaranteeing a skin-friendly inner layer and a flame-retardant outer layer, resulting in excellent overall performance.

[0039] 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 insulating cotton is 40 g / m². 2 -200g / m 2 The insulating cotton of this invention can effectively achieve lightweighting while ensuring warmth. 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.

[0040] In some embodiments of the present invention, a nonwoven fabric is laminated to the outermost layer and / or the outermost layer. The nonwoven fabric is made of polypropylene, polyethylene terephthalate, or recycled polyethylene terephthalate. Laminated with a nonwoven fabric to the outermost layer and / or the outermost layer better maintains the insulation's condition after washing, preventing collapse and deformation. The outermost layer refers to the side of the innermost layer furthest from the middle or outermost layer, i.e., the side closest to the user; the outermost layer refers to the side furthest from the user. In the above embodiments, the lamination can be performed using a nonwoven process, such as needle punching. Optionally, the nonwoven fabric has a basis weight of 8 g / m². 2 -30g / m 2 .

[0041] To further improve the functionality of the thermal insulation cotton, some specific functional materials can be added to the thermal insulation cotton of this invention to achieve functions such as far-infrared radiation, antibacterial properties, and antistatic properties.

[0042] For example, in some embodiments of the present invention, the thermal insulation cotton further comprises uniformly dispersed far-infrared ceramic powder, which is attached to the surface of the polyimide fiber.

[0043] Secondly, the present invention provides the application of the above-mentioned thermal insulation cotton in the preparation of textiles with heat-insulating and flame-retardant properties.

[0044] Thirdly, the present invention provides a method for preparing the above-mentioned thermal insulation cotton, comprising:

[0045] First, a polyimide fiber web is prepared by electrospinning. The obtained polyimide fiber web is then impregnated in an aerogel sol to prepare the innermost layer.

[0046] The fiber raw materials of the middle layer and the outermost layer are mixed, opened, combed and laid into a web to form a multi-layer fiber web. After baking and shaping, the middle layer and the outermost layer are obtained.

[0047] The innermost layer is connected to the middle and outermost layers using a nonwoven process.

[0048] In some embodiments of the present invention, the innermost layer can be connected to the middle and outermost layers by a needle-punching method.

[0049] Understandably, when the insulation material does not include a middle layer, the preparation method also does not include the preparation of the middle layer, and the innermost layer and the outermost layer are directly connected by a nonwoven process.

[0050] In some embodiments of the present invention, during the baking and shaping step, the fiber web runs at a speed of 3-4 m / min in the oven, the oven temperature is 135°C for the upper web, 140°C for the middle web, and 145°C for the lower web, and the oven wind speed is 40-50 Hz.

[0051] This invention employs a hot air method for fiber web consolidation, resulting in a fluffy, soft, and pressure-free insulating cotton. The hot air method does not rely on roller pressure; instead, hot air penetrates the fiber web to melt the heat-melting components (low-melting-point fibers in this invention), which then form bonding points at the fiber intersections upon cooling. Research in this invention has revealed that three parameters—the fiber web's travel speed (residence time), the oven temperature, and the oven airflow—must be controlled synergistically. If any one parameter fails to meet these requirements, the uniformity, fluffiness, and softness of the resulting insulating cotton will be affected, and all three cannot be achieved simultaneously.

[0052] To facilitate understanding of the thermal insulation cotton and its preparation method provided by the present invention, some specific embodiments are described below.

[0053] In the following examples, the polyimide fiber used is a three-dimensional crimped polyimide fiber, and the low-melting-point fiber used is a low-melting-point polyester fiber.

[0054] For ease of performance comparison, the basis weight of the thermal insulation cotton prepared in the following examples and comparative examples is 140 g / m². 2 .

[0055] Example 1

[0056] This embodiment provides a thermal insulation cotton with a two-layer structure. With the innermost layer closest to the user as the innermost layer, the innermost layer includes 10% polyimide fiber and 90% aerogel fiber by weight percentage. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber fills the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64mm.

[0057] The outermost layer is formed by nonwoven technology using 40% polyimide fiber, 5% aramid fiber, 50% polyester fiber and 5% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0058] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0059] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0060] 2) Mix, open, comb, and lay the outermost layer of fiber raw materials into a web, which is laid in an interlaced manner to form a multi-layered fiber web;

[0061] 3) The fiber web is sent into the 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℃ for the upper web, 140℃ for the middle web, and 145℃ for the lower web. The oven wind speed is 45 Hz. The outermost layer is prepared. The thickness of the outermost layer is the same as that of the innermost layer.

[0062] 4) Connect the innermost and outermost layers by needle punching;

[0063] 5) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0064] Example 2

[0065] This embodiment provides a thermal insulation cotton with a two-layer structure. With the innermost layer closest to the user as the innermost layer, the innermost layer comprises 30% polyimide fiber and 70% aerogel fiber by weight percentage. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber fills the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64mm.

[0066] The outermost layer is formed by nonwoven technology using 60% polyimide fiber, 10% aramid fiber, 15% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0067] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0068] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0069] 2) Mix, open, comb, and lay the outermost layer of fiber raw materials into a web, which is laid in an interlaced manner to form a multi-layered fiber web;

[0070] 3) The fiber web is sent into the 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℃ for the upper web, 140℃ for the middle web, and 145℃ for the lower web. The oven wind speed is 45 Hz. The outermost layer is obtained. The thickness of the innermost layer is 1.5 times that of the outermost layer.

[0071] 4) Connect the innermost and outermost layers by needle punching;

[0072] 5) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0073] Example 3

[0074] This embodiment provides a thermal insulation cotton with a two-layer structure. With the innermost layer closest to the user as the innermost layer, by weight percentage, the innermost layer includes 20% polyimide fiber and 80% aerogel fiber. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber fills the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64mm.

[0075] The outermost layer is formed by nonwoven technology using 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0076] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0077] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0078] 2) Mix, open, comb, and lay the outermost layer of fiber raw materials into a web, which is laid in an interlaced manner to form a multi-layered fiber web;

[0079] 3) The fiber web is sent into the 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℃ for the upper web, 140℃ for the middle web, and 145℃ for the lower web. The oven wind speed is 45 Hz. The outermost layer is prepared. The thickness of the outermost layer is the same as that of the innermost layer.

[0080] 4) Connect the innermost and outermost layers by needle punching;

[0081] 5) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0082] Example 4

[0083] This embodiment provides a thermal insulation cotton with a three-layer structure. With the layer closest to the user as the innermost layer, the innermost layer includes 20% polyimide fiber and 80% aerogel fiber by weight percentage. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber fills the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64mm.

[0084] The middle layer is formed by nonwoven process of 35% polyimide fiber, 45% polyester fiber and 20% low melting point fiber. The denier of polyimide fiber is 0.8D-5D and the length is 32-64mm. The denier of polyester fiber is 1.5D-7D and the length is 32-74mm.

[0085] The outermost layer is formed by nonwoven technology using 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0086] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0087] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0088] 2) Mix, open, comb, and lay the fiber raw materials of the middle layer and the outermost layer separately. The laying of the web is a cross-laying web to form a multi-layer fiber web;

[0089] 3) The fiber web is placed in 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℃ for the top web, 140℃ for the middle web, and 145℃ for the bottom web. 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.

[0090] 4) Connect the innermost layer to the already baked and solidified middle and outermost layers by needle punching;

[0091] 5) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0092] Example 5

[0093] This embodiment provides a thermal insulation cotton with a three-layer structure. With the layer closest to the user as the innermost layer, the innermost layer includes 20% polyimide fiber and 80% aerogel fiber by weight percentage. Specifically, the polyimide fiber forms a three-dimensional skeleton network, and the aerogel fiber fills the three-dimensional skeleton network. The polyimide fiber has a denier of 1D-3D and a length of 32-64mm.

[0094] The middle layer is formed by nonwoven process of 35% polyimide fiber, 45% polyester fiber and 20% low melting point fiber. The denier of polyimide fiber is 0.8D-5D and the length is 32-64mm. The denier of polyester fiber is 1.5D-7D and the length is 32-74mm.

[0095] The outermost layer is formed by nonwoven technology using 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0096] The outermost layer is further laminated with a layer of polypropylene nonwoven fabric, with a basis weight of 10 g / m². 2 .

[0097] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0098] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0099] 2) Mix, open, comb, and lay the fiber raw materials of the middle layer and the outermost layer separately. The laying of the web is a cross-laying web to form a multi-layer fiber web;

[0100] 3) The fiber web is sent into the 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℃ for the top web, 140℃ for the middle web, and 145℃ for the bottom web. The oven wind speed is 45 Hz. The middle layer and the outermost layer are prepared. The thickness of the outermost layer, the middle layer, and the innermost layer are the same.

[0101] 4) Connect the innermost layer to the already baked and solidified middle and outermost layers by needle punching;

[0102] 5) A layer of polypropylene nonwoven fabric is needle-punched onto the outermost layer;

[0103] 6) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0104] Example 6

[0105] This embodiment provides a thermal insulation cotton with a two-layer structure. With the innermost layer closest to the user as the innermost layer, the innermost layer is formed by non-woven process using 20% ​​polyimide fiber and 80% aerogel fiber by weight percentage. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm.

[0106] The outermost layer is formed by nonwoven technology using 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. 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, and the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm.

[0107] This embodiment also provides a method for preparing the above-mentioned thermal insulation cotton, as follows:

[0108] 1) Mix, open, comb, and lay the innermost layer of fiber raw materials to form a multi-layer fiber web;

[0109] 2) Mix, open, comb, and lay the outermost layer of fiber raw materials to form a multi-layer fiber web;

[0110] 3) Stack the fiber webs from steps 1) and 2) and put them into an oven for baking and shaping. The running speed of the fiber webs in the oven is 3.5 m / min, the oven temperature is 135℃ for the top web, 140℃ for the middle web, and 145℃ for the bottom web, and the oven wind speed is 45 Hz. The cured fiber web is obtained; the thickness of the outermost layer is the same as the thickness of the innermost layer.

[0111] 4) Finish the surface of the thermal insulation cotton, cut it into rolls, and obtain the finished product.

[0112] Comparative Example 1

[0113] This comparative example provides a common thermal insulation cotton, which is 100% polyester and has a single-layer structure.

[0114] Comparative Example 2

[0115] This comparative example uses pure down as a reference.

[0116] Comparative Example 3

[0117] This comparative example provides a thermal insulation cotton with a single-layer structure, consisting of a three-dimensional skeleton network formed by polyimide fibers, with aerogel fibers filling the three-dimensional skeleton network. The polyimide fibers have a denier of 1D-3D and a length of 32-64mm.

[0118] The preparation method is as follows: polyimide fiber web is obtained by electrospinning, the obtained polyimide fiber web is impregnated in aerogel sol, and dried under normal pressure to prepare thermal insulation cotton.

[0119] Comparative Example 4

[0120] This comparative example provides a thermal insulation cotton with a single-layer structure, formed by nonwoven technology from 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm, of which the polyimide fiber with a denier of 0.8D-1.5D accounts for 85% of the total amount of the outermost polyimide fiber. The aramid fiber has a denier of 1.2D-3D and a length of 32-64mm, and the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm.

[0121] Its preparation method is as follows:

[0122] The fiber raw materials are mixed, opened, combed, and laid into a web in an interlaced manner to form a multi-layered fiber web. The fiber web is then sent into an oven for baking and shaping. The fiber web runs at a speed of 3.5 m / min in the oven, and the oven temperature is 135℃ for the top web, 140℃ for the middle web, and 145℃ for the bottom web. The oven wind speed is 45 Hz, and the thermal insulation cotton is prepared.

[0123] Comparative Example 5

[0124] This comparative example provides a thermal insulation cotton with a two-layer structure. With the innermost layer closest to the user as the innermost layer, by weight percentage, the innermost layer is formed by a nonwoven process from 35% polyimide fiber, 45% polyester fiber, and 20% low-melting-point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm, while the polyester fiber has a denier of 1.5D-7D and a length of 32-74mm.

[0125] The outermost layer is formed by nonwoven technology using 50% polyimide fiber, 5% aramid fiber, 30% polyester fiber and 15% low melting point fiber. The polyimide fiber has a denier of 0.8D-5D and a length of 32-64mm. Among them, 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 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.

[0126] Its preparation method is as follows:

[0127] 1) Mix, open, comb, and lay the innermost and outermost fiber raw materials separately, and lay them into a web in an interlaced manner to form a multi-layered fiber web;

[0128] 2) The fiber web is sent into the 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℃ for the upper web, 140℃ for the middle web, and 145℃ for the lower web. The oven wind speed is 45 Hz. The thermal insulation cotton is prepared. The thickness of the outermost layer is the same as the thickness of the innermost layer.

[0129] 3) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0130] Comparative Example 6

[0131] This comparative example provides a thermal insulation cotton, whose structure and composition are the same as in Example 3, and its preparation method is as follows:

[0132] 1) Polyimide fiber web was prepared by electrospinning, and the obtained polyimide fiber web was impregnated in aerogel sol and dried under normal pressure to prepare the innermost layer;

[0133] 2) Mix, open, comb, and lay the outermost layer of fiber raw materials into a web, which is laid in an interlaced manner to form a multi-layered fiber web;

[0134] 3) The fiber web is placed in an oven for baking and shaping. The fiber web runs at a speed of 4.5 m / min in the oven, the oven temperature is 140℃, and the oven wind speed is 55 Hz to obtain the outermost layer. The thickness of the outermost layer is the same as that of the innermost layer.

[0135] 4) Connect the innermost and outermost layers by needle punching;

[0136] 5) Finally, the surface of the thermal insulation cotton is finished, and it is cut into rolls to obtain the finished product.

[0137] Performance testing

[0138] Test method:

[0139] The standard for testing the thermal resistance and clo value of fabrics is GB / T 11048-2008; the thermal resistance and clo value of fabrics characterize their warmth retention, and the higher the value, the better.

[0140] The testing standards for loft, compression ratio, and recovery rate are Appendix A of FZ / T64003-2021. Loft is an indicator that measures the volume occupied by a unit mass of thermal insulation cotton. It directly reflects the looseness of the insulation cotton and its ability to hold air. The higher the value, the larger the volume, the looser the structure, and the higher the air content for the same weight. Compression ratio is an indicator that measures the degree of volume reduction of thermal insulation cotton under external force. It directly reflects the compressive strength and space compression efficiency of its loose structure. Recovery rate characterizes the resilience of thermal insulation cotton after compression; the higher the value, the better.

[0141] The Limiting Oxygen Index (LOI) test standard is ASTM D2863; it determines 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.

[0142] Durability: The rate of heat retention (clo value) after 20 repeated washes.

[0143] The test results are shown in Table 1.

[0144] Table 1

[0145]

[0146] The results above show that the embodiments of the present invention, through the use of a composite structure design, achieve lightweight and skin-friendly warmth by selecting a specific ratio of polyimide fiber and aerogel fiber in the innermost layer, while the outermost layer uses a specific ratio of polyimide fiber, aramid fiber, polyester fiber, and low-melting-point fiber to work synergistically, further enhancing the heat insulation effect and taking into account flame retardant properties, thus obtaining a warm cotton that combines heat insulation, lightweight, and flame retardancy. Among them, Example 4 adds an extra middle layer, resulting in better heat insulation. Example 5 further composites a non-woven fabric layer on the outermost layer to increase the durability of the warm cotton. Comparing Comparative Examples 1-5 with the embodiments fully illustrates the importance of the structure and composition of the warm cotton of the present invention. In the preparation process of Comparative Example 6, the three parameters of the fiber web running speed (i.e., residence time), oven temperature, and oven wind speed were not controlled synergistically, resulting in a warm cotton that could not simultaneously achieve uniformity, fluffiness, and softness.

[0147] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A type of thermal insulation cotton, characterized in that, It has at least two layers. With the innermost layer closest to the user as the innermost layer, by weight percentage, the innermost layer comprises 10%-30% polyimide fiber and 70%-90% aerogel fiber, wherein the polyimide fiber forms a three-dimensional skeleton network and the aerogel fiber is filled therein; the outermost layer is formed by a nonwoven process from 40%-60% polyimide fiber, 5%-10% aramid fiber, 15%-50% polyester fiber and 5%-15% low melting point fiber. 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.

2. The thermal insulation cotton according to claim 1, characterized in that, Between the innermost and outermost layers, there are one or more intermediate layers, the intermediate layers comprising polyimide fibers, polyester fibers and low-melting-point fibers, wherein the content of polyimide fibers increases from the innermost layer to the outermost layer.

3. The thermal insulation cotton according to claim 1 or 2, characterized in that, The thickness of the innermost layer is 1-1.5 times that of the outermost layer, and the weight of the insulating cotton is 40g / m². 2 -200g / m 2 .

4. The thermal insulation cotton according to claim 1 or 2, characterized in that, A nonwoven fabric is laminated to the outermost layer and / or the outermost layer. The nonwoven fabric is made of polypropylene or polyethylene terephthalate and has a basis weight of 8 g / m². 2 -30g / m 2 .

5. The thermal insulation cotton according to claim 4, characterized in that, The polyethylene terephthalate is a recycled polyethylene terephthalate.

6. The thermal insulation cotton according to claim 1 or 2, characterized in that, It also contains uniformly dispersed far-infrared ceramic powder, which is attached to the surface of polyimide fibers.

7. The use of the thermal insulation cotton according to any one of claims 1-6 in the preparation of textiles with thermal insulation and flame retardant properties.

8. The method for preparing the thermal insulation cotton according to any one of claims 1-6, characterized in that, include: First, a polyimide fiber web is prepared by electrospinning. The obtained polyimide fiber web is then impregnated 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 into a web to form a multi-layer fiber web. After baking and shaping, the middle layer and the outermost layer are obtained. The innermost layer is connected to the middle and outermost layers using a nonwoven process.

9. The method for preparing thermal insulation cotton according to claim 8, characterized in that, In the baking and shaping step, the fiber web runs at a speed of 3-4 m / min in the oven, the oven temperature is 135℃ for the upper web, 140℃ for the middle web, and 145℃ for the lower web, and the oven wind speed is 40-50 Hz.

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