Ultrathin high-strength ceramic fiber paper and preparation method thereof

Abstract

The invention provides ultrathin high-strength ceramic fiber paper and a preparation method thereof. The preparation method comprises the following steps: (1) preparing functional fibers with skin-core structures by adopting a composite spinning process; wherein the skin layer of the functional fiber is made of a thermoplastic polymer material, and the core layer of the functional fiber is made of a ceramifiable polymer material; and (2) dispersing and uniformly mixing the functional fibers and ceramic fibers to obtain mixed fiber slurry, carrying out wet molding on the mixed fiber slurry, and then drying and curing to obtain the ultrathin high-strength ceramic fiber paper. The prepared ceramic fiber paper has ultra-thin thickness, the thickness of the ceramic fiber paper can be controlled within 0.5 mm, and the ceramic fiber paper has high strength, good assembly flexibility and the performance of being capable of resisting the ultra-high temperature of 1000 DEG C or above for a long time.

Description

Technical Field

[0001] This invention relates to the field of wet-process thermal insulation and protection technology, and in particular to an ultra-thin high-strength ceramic fiber paper and its preparation method. Background Technology

[0002] In the field of high-temperature thermal insulation, ceramic fiber paper, with its excellent thermal insulation performance and high cost-effectiveness, is widely used in new energy battery safety protection, aerospace thermal management, and electronic device thermal insulation, becoming an important thermal insulation substrate. Compared with more expensive quartz fiber and zirconium oxide fiber, ceramic fiber paper has greater advantages in terms of economy and development potential, and is especially suitable for cost-sensitive applications that require both thermal insulation performance and cost-effectiveness.

[0003] However, most ceramic fiber papers currently on the market are used in high-stress environments and are typically quite thick. Many emerging applications, however, require further thinning of the material to achieve space saving and lightweighting. Traditional processes often lead to a decrease in mechanical strength and thermal insulation integrity when reducing thickness. The strength performance of conventional ceramic fiber paper at room temperature mainly depends on the added organic or inorganic binders. Commonly used inorganic binders, such as sodium silicate and phosphates, while imparting some initial strength, often result in decreased toughness and increased brittleness, making the paper prone to breakage during use. While organic binders can improve the material's flexibility, their poor heat resistance makes it difficult to maintain stable performance in ultra-high temperature environments. This contradiction severely restricts the application of ultra-thin ceramic fiber paper in high-stress and high-temperature environments.

[0004] Therefore, there is an urgent need to provide an ultra-thin, high-strength ceramic fiber paper and its preparation method. Summary of the Invention

[0005] This invention provides an ultrathin high-strength ceramic fiber paper and its preparation method, which can solve the problem that existing ceramic fiber papers cannot achieve both good room temperature mechanical properties and high temperature resistance while ensuring a relatively thin thickness.

[0006] In a first aspect, the present invention provides a method for preparing ultrathin high-strength ceramic fiber paper, the method comprising the following steps: (1) A functional fiber with a core-sheath structure is prepared by a composite spinning process; wherein the sheath of the functional fiber is a thermoplastic polymer material and the core is a ceramic polymer material; (2) The functional fiber and ceramic fiber are dispersed and mixed to obtain a mixed fiber slurry, and the mixed fiber slurry is wet-formed, and then dried and cured to obtain the ultra-thin high-strength ceramic fiber paper.

[0007] Preferably, in step (1), the outer layer of the functional fiber is one of polyethylene, copolyamide or copolyester, and the core layer is one of ceramicizable styrene-butadiene rubber, ceramicizable cis-butadiene rubber, ceramicizable silicone rubber, ceramicizable nitrile rubber, ceramicizable EPDM rubber or ceramicizable polyolefin.

[0008] Preferably, in step (1), the functional fiber has a sheath layer accounting for 20-25 wt% and a core layer accounting for 75-80 wt%.

[0009] Preferably, the functional fiber with a core-sheath structure is prepared in the following manner: (11) Add the skin layer material and the core layer material into separate screw extruders for melting to obtain core layer melt and skin layer melt; (12) In the composite spinning assembly, the skin melt is guided by the distribution plate to form a surrounding tubular fluid, while the core melt is guided to the central channel of the tubular fluid, and the tubular skin fluid and the core fluid in the central channel are combined in the composite cavity to form a pre-formed fluid with a skin-core structure. (13) The preformed fluid is extruded through a concentric core-sheath composite spinneret and cooled and solidified to obtain the functional fiber with a core-sheath structure.

[0010] Preferably, in step (11), the melt extrusion temperature of the skin material is 200~260℃, and the melt extrusion temperature of the core material is 100~150℃.

[0011] Preferably, in step (13), the extrusion pressure is 0.8~1.2MPa; the aperture of the concentric circle core-shell composite spinneret is 0.2~0.4mm and the length-to-diameter ratio is 2:1.

[0012] Preferably, the cooling and curing method is ring-blowing cooling, with an air temperature of 16~19℃ and an air speed of 0.3~0.5m / s.

[0013] Preferably, the ceramic fiber is one of alumina fiber, mullite fiber, or aluminosilicate fiber.

[0014] More preferably, the ceramic fibers have a diameter of 0.3~3μm, a length of 0.3~6mm, and a slag ball content of ≤0.5%.

[0015] Preferably, in step (2), the mass ratio of functional fiber to ceramic fiber is (0.4~0.5):1.

[0016] Preferably, in step (2), the concentration of the mixed fiber slurry is 0.5~1.5wt%, and the pH value is 2.0~3.0. Preferably, in step (2), during the wet molding process, the dehumidification vacuum degree is 0.03~0.05Mpa, and the forced vacuum degree is 0.04~0.06Mpa.

[0017] Preferably, in step (2), the drying temperature is 140-160℃, the curing temperature is 150-170℃, and the time is 10-15min.

[0018] More preferably, a two-stage gradient heating method is used for drying; the temperature of the first stage is 80~100℃ and the heating rate is 40~60℃ / min, and the temperature of the second stage is 120~140℃ and the heating rate is 10~15℃ / min.

[0019] Secondly, embodiments of the present invention also provide an ultrathin high-strength ceramic fiber paper, which is prepared by any of the preparation methods described in the first aspect above; wherein the ceramic fiber paper has a thickness of 0.2~0.5mm, a temperature resistance of 800~1200℃, and a tensile strength of 0.25~0.50kN / m.

[0020] Compared with the prior art, the present invention has at least the following beneficial effects: In this invention, functional fibers with a core-sheath structure are first prepared through a composite spinning process. The sheath of this functional fiber has a low glass transition temperature (T0). g A thermoplastic polymer material with a core layer of ceramizable polymer material. By combining functional fibers and ceramic fibers of this core-shell structure, low Tg is achieved during the curing stage of the wet molding process. g The outer layer fibers undergo a glass transition upon heating, firmly bonding the ceramic fibers through physical entanglement and thermal adhesion. This significantly improves the strength and flexibility of the ceramic fiber paper at room temperature, effectively avoiding the brittleness problems caused by traditional inorganic binders. In ultra-high temperature environments, the ceramicizable core fibers melt to form a liquid phase and then resolidify through a sintering reaction into a continuous, dense, and hard ceramic protective layer. This protective layer can withstand temperatures up to 1200°C and firmly binds the remaining carbonaceous skeleton, forming a ceramic body with high mechanical strength. This effectively maintains the overall shape and structural integrity of the ceramic fiber paper under ultra-high temperature conditions, overcoming its shrinkage problem. Thus, the ceramic fiber paper prepared in this invention has an ultra-thin thickness, controllable to within 0.5 mm, and possesses high strength, good assembly flexibility, and the ability to withstand ultra-high temperatures above 1000°C for extended periods. Detailed Implementation

[0021] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are some embodiments of the present invention, but not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0022] As mentioned earlier, due to their inherent rigidity, ceramic fibers are difficult to form a uniform and stable fiber network structure during wet molding, resulting in inconsistent strength in the prepared ceramic fiber paper, making it unsuitable for high-stress environments. Currently, the room-temperature strength of conventional ceramic fiber paper mainly depends on organic or inorganic binders. Common inorganic binders such as water glass (sodium silicate) and phosphates significantly reduce the material's toughness, making it prone to brittle fracture. While organic binders can improve flexibility, they are limited by temperature resistance and cannot maintain stable performance under ultra-high temperature conditions. Furthermore, in ultra-high temperature environments, ceramic fibers are prone to sintering and grain growth, leading to increased brittleness, decreased strength, and volume shrinkage, severely affecting structural stability and service life.

[0023] For example, Chinese patent CN120149745A discloses a high-temperature insulating and corrosion-resistant lithium battery ceramic fiber paper and its preparation method. This method involves doping ceramic fibers with rare earth phosphate materials to enhance their crystal structure, improve their mechanical strength and thermal stability, thereby extending the service life of the ceramic fiber paper. However, this method has the following problems in practical industrial applications: the introduction of rare earth phosphates usually involves multi-step doping and high-temperature sintering, requiring highly sophisticated equipment and control, resulting in low production efficiency and significantly increased costs, which is not conducive to large-scale production; furthermore, the above method focuses on modifying the material composition and still fails to solve the problem of difficult forming of ceramic fibers due to their high brittleness and easy breakage during wet forming, leaving the initial strength problem of ultra-thin ceramic fiber paper still present.

[0024] Based on this, embodiments of the present invention provide a method for preparing ultrathin high-strength ceramic fiber paper, the method comprising the following steps: (1) A functional fiber with a core-sheath structure is prepared by a composite spinning process; wherein the sheath of the functional fiber is a thermoplastic polymer material and the core is a ceramic polymer material; (2) The functional fiber and ceramic fiber are dispersed and mixed to obtain a mixed fiber slurry, and the mixed fiber slurry is wet-formed, and then dried and cured to obtain the ultra-thin high-strength ceramic fiber paper.

[0025] In this embodiment of the invention, functional fibers with a core-sheath structure are first prepared by a composite spinning process. The sheath of this functional fiber has a low glass transition temperature (T0).g A thermoplastic polymer material with a core layer of ceramizable polymer material. By combining functional fibers and ceramic fibers of this core-shell structure, low Tg is achieved during the curing stage of the wet molding process. g The outer layer fibers undergo a glass transition upon heating, firmly bonding the ceramic fibers through physical entanglement and thermal adhesion. This significantly improves the strength and flexibility of the ceramic fiber paper at room temperature, effectively avoiding the brittleness problems caused by traditional inorganic binders. In ultra-high temperature environments, the ceramicizable core fibers melt to form a liquid phase and then resolidify through a sintering reaction into a continuous, dense, and hard ceramic protective layer. This protective layer can withstand temperatures up to 1200°C and firmly binds the remaining carbonaceous skeleton, forming a ceramic body with high mechanical strength. This effectively maintains the overall shape and structural integrity of the ceramic fiber paper under ultra-high temperature conditions, overcoming its shrinkage problem. Thus, the ceramic fiber paper prepared in this invention has an ultra-thin thickness, controllable to within 0.5 mm, and possesses high strength, good assembly flexibility, and the ability to withstand ultra-high temperatures above 1000°C for extended periods.

[0026] According to some preferred embodiments, in step (1), the outer layer of the functional fiber is one of polyethylene, copolyamide or copolyester, and the core layer is one of ceramicizable styrene-butadiene rubber, ceramicizable cis-butadiene rubber, ceramicizable silicone rubber, ceramicizable nitrile rubber, ceramicizable ethylene propylene diene monomer rubber or ceramicizable polyolefin; in the functional fiber, the proportion of the outer layer is 20~25wt% (for example, it can be 20wt%, 21wt%, 22wt%, 23wt%, 24wt% or 25wt%), and the proportion of the core layer is 75~80wt% (for example, it can be 75wt%, 76wt%, 77wt%, 78wt%, 79wt% or 80wt%).

[0027] The functional fibers in the embodiments of the present invention, through the use of the above-mentioned low-T fibers, g The plasticizable polymer serves as the skin layer, possessing a defined and adjustable melting temperature, excellent melt flowability, and fiber-forming properties. It can undergo a glass transition during the wet molding and curing stage, achieving uniform bonding of fibers. The core layer is a polymer material that can be ceramicized at high temperatures. Its ceramicized components form a continuous, dense, and thermally stable ceramic protective layer after the matrix decomposes. Simultaneously, by precisely controlling the ratio of the skin layer to the core layer in the functional fibers of the skin-core structure, the prepared ceramic fiber paper exhibits excellent comprehensive performance under both room temperature and ultra-high temperature environments.

[0028] Experiments conducted according to this invention have confirmed that while a high proportion of the sheath layer can improve the bonding of the fiber paper at room temperature, it can also excessively compress the pores of the fiber network, affecting the material's air permeability and high-temperature thermal stability. Conversely, a low proportion of the sheath layer can result in insufficient bonding performance of the fibers at room temperature, making it difficult to form effective inter-fiber bonds and leading to a significant decrease in room temperature strength and toughness. Simultaneously, a low proportion of the core layer will result in a discontinuous and insufficiently thick ceramic protective layer, making it unable to effectively resist high-temperature erosion and structural shrinkage. Conversely, a high proportion of the core layer will compress the bonding volume of the sheath layer, thereby reducing its mechanical properties at room temperature. Therefore, this invention, through reasonable optimization of the sheath-core ratio and full utilization of the excellent bonding characteristics of the selected sheath material and the ceramic-forming properties of the core material, ensures both excellent ultra-high temperature bonding performance and forming flexibility of the fiber paper, while also ensuring the formation of a complete and dense ceramic protective layer at high temperatures. This ultimately enables the ultra-thin ceramic fiber paper to possess high toughness, high strength, and long-term resistance to ultra-high temperatures.

[0029] It should be noted that, in the embodiments of the present invention, the ceramicizable polymer material used in the core layer specifically refers to a polymer material composed of a polymer matrix, ceramic fillers (such as glass powder, mica, clay, etc.), and a flux. The ceramic filler aims to melt and form a ceramic phase with sufficient mechanical strength within the target ceramicization temperature range (e.g., 600℃~1200℃). The flux lowers the eutectic temperature of the ceramic filler system, promoting the formation of a denser ceramic body. The aforementioned ceramicizable polymer material can be obtained using existing preparation methods, which will not be elaborated upon here.

[0030] According to some preferred embodiments, the functional fiber having a core-sheath structure is prepared in the following manner: (11) Add the skin layer material and the core layer material into separate screw extruders for melting to obtain core layer melt and skin layer melt; (12) In the composite spinning assembly, the skin melt is guided by the distribution plate to form a surrounding tubular fluid, while the core melt is guided to the central channel of the tubular fluid, and the tubular skin fluid and the core fluid in the central channel are combined in the composite cavity to form a pre-formed fluid with a skin-core structure. (13) The preformed fluid is extruded through a concentric core-sheath composite spinneret and cooled and solidified to obtain the functional fiber with a core-sheath structure.

[0031] According to some preferred embodiments, in step (11), the melt extrusion temperature of the skin material is 200~260℃ (e.g., 200℃, 210℃, 220℃, 230℃, 240℃, 250℃ or 260℃), and the melt extrusion temperature of the core material is 100~150℃ (e.g., 100℃, 110℃, 120℃, 130℃ or 140℃); in step (13), the extrusion pressure is 0.8~1.2MPa (e.g., 0.8MPa, 0.9MPa, etc.). The pressure is 1.0 MPa, 1.1 MPa, or 1.2 MPa; the aperture of the concentric circular core-shell composite spinneret is 0.2~0.4 mm (e.g., 0.2 mm, 0.3 mm, or 0.4 mm), and the aspect ratio is 2:1; preferably, the cooling and curing method is ring-blowing cooling, the air temperature is 16~19℃ (e.g., 16℃, 17℃, 18℃, or 19℃), and the air velocity is 0.3~0.5 m / s (e.g., 0.3 m / s, 0.4 m / s, or 0.5 m / s).

[0032] In this embodiment of the invention, the sheath material and core material are first added to independent screw extruders, and the temperatures of the two machines are controlled to melt them. During the melting process of the core material, the melting extrusion temperature of the core layer is precisely controlled at the aforementioned temperature, thereby enabling the core layer to melt stably at a low temperature and effectively avoiding pre-vulcanization of the rubber. If the temperature is too high, the vulcanizing agent and ceramic filler in the additives will react prematurely at high temperatures, causing the rubber compound to cross-link in the barrel. This can result in a rough product surface or even block the mold, leading to production interruption. At the same time, controlling the reasonable ratio of sheath and core material during transportation helps to ensure that the sheath melt can uniformly coat the core layer and form a stable pre-formed fluid. Finally, under specific spinning pressure and ring blowing cooling conditions, structurally complete sheath-core fiber is successfully produced.

[0033] It should be noted that before melting the skin and core materials, a step is included in drying them in a forced-air oven at 60-70°C for 5-6 hours. This step removes moisture from the surface of the materials to prevent bubbles or filament breakage during spinning.

[0034] According to some preferred embodiments, in step (2), the ceramic fiber is one of alumina fiber, mullite fiber or aluminosilicate fiber; the diameter of the ceramic fiber is 0.3~3μm (for example, it can be 0.3μm, 0.5μm, 0.8μm, 1.0μm, 1.5μm, 1.8μm or 2μm), the length is 0.3~6mm (for example, it can be 0.3mm, 0.5mm, 1mm, 2mm, 3mm, 4mm or 5mm), and the slag ball content is ≤0.5%.

[0035] In this embodiment of the invention, the above-mentioned types of ceramic fibers are selected as the substrate, and by controlling their diameter and length parameters, it is beneficial to enable the fibers to fully interweave during the wet forming process to form a dense and uniform three-dimensional network skeleton, ensuring the uniformity and integrity of the ultra-thin structure of the fiber paper, and ultimately enabling the ceramic fiber paper to have good room temperature strength, excellent thermal stability and ultra-thin performance.

[0036] According to some preferred embodiments, in step (2), the mass ratio of functional fiber to ceramic fiber is (0.4~0.5):1 (for example, it can be 0.4:1, 0.45:1 or 0.5:1).

[0037] In this embodiment of the invention, by strictly controlling the ratio of functional fibers to ceramic fibers during the wet forming process, it is beneficial to ensure that the ceramic fiber paper has excellent room temperature strength and flexibility while also ensuring its excellent thermal stability at high temperatures, thus achieving a performance balance throughout its entire life cycle from room temperature to ultra-high temperature. If the content of functional fibers is too low, it will be detrimental to ensuring the mechanical properties of the ceramic fiber paper at room temperature and its thermal stability at high temperatures. If the content of functional fibers is too high and the content of ceramic fibers is too low, the excessive decomposition of organic polymers at high temperatures will cause the fiber paper to produce too many pores, thereby weakening the continuity of the ceramic protective layer and causing a decrease in the thermal stability of the fiber paper at high temperatures. Conversely, if the content of ceramic fibers is too high, the mechanical properties of the fiber paper at room temperature will be poor.

[0038] According to some preferred embodiments, in step (2), the concentration of the mixed fiber slurry is 0.5~1.5wt% (e.g., 0.5wt%, 0.8wt%, 1.0wt%, 1.2wt%, or 1.5wt%), and the pH value is 2.0~3.0 (e.g., 2.0, 2.5, or 3.0). In step (2), during the wet molding process, the dehumidification vacuum degree is 0.03~0.05MPa (e.g., 0.03MPa, 0.04MPa, or 0.05MPa), and the forced vacuum degree is 0.04~0.06MPa (e.g., 0.04MPa, 0.05MPa, or 0.06MPa). In step (2), the drying temperature is 140-160℃ (e.g., 140℃, 150℃, or 160℃), the curing temperature is 150-170℃ (e.g., 150℃, 160℃, or 170℃), and the time is 10-15min (e.g., 10min, 12min, or 15min). Preferably, a two-stage gradient heating method is used for drying. The temperature of the first stage is 80-100℃ (e.g., 80℃, 90℃, or 100℃), and the heating rate is 40-60℃ / min (e.g., 40℃ / min, 50℃ / min, or 60℃ / min). The temperature of the second stage is 120-140℃ (e.g., 120℃, 130℃, or 140℃), and the heating rate is 10-15℃ / min (e.g., 10℃ / min, 12℃ / min, or 15℃ / min).

[0039] In this embodiment of the invention, high-temperature resistant ultrathin high-strength ceramic fiber paper is prepared by mixing and dissolving functional fibers with a core-sheath structure and ceramic fibers through a wet forming process. During the curing stage, the low Tg of the functional fibers... g The outer layer undergoes a glass transition upon heating, significantly enhancing the room-temperature mechanical strength and flexibility of ultrathin ceramic fiber paper through physical entanglement and thermal bonding. Under ultra-high temperature conditions, the ceramicizable polymers in the core layer undergo a ceramic transformation, forming a dense and hard ceramic protective layer on the fiber surface. This effectively suppresses dimensional shrinkage at extreme temperatures, solving the problem of severe dimensional shrinkage in ultrathin ceramic fiber paper that prevents its application in high-stress and ultra-high-temperature environments. Furthermore, this method is simple and environmentally friendly.

[0040] The present invention also provides an ultrathin high-strength ceramic fiber paper prepared by any of the above-described preparation methods; wherein the ceramic fiber paper has a thickness of 0.2~0.5 mm, a temperature resistance of 800~1200℃, and a tensile strength of 0.25~0.50 kN / m.

[0041] To more clearly illustrate the technical solution and advantages of the present invention, several embodiments are provided below to describe in detail an ultra-thin high-strength ceramic fiber paper and its preparation method. In the following embodiments, the ceramicizable EPDM rubber specifically comprises the following components: by mass, 100 parts of EPDM rubber matrix, 20 parts of mica powder, 10 parts of calcium borate, 16 parts of ammonium polyphosphate, 30 parts of zinc borate, 10 parts of organically modified montmorillonite, and 10 parts of vulcanizing agent; the ceramicizable styrene-butadiene rubber specifically comprises the following components: 100 parts of styrene-butadiene rubber matrix, 10 parts of silica... The following components are used to make ceramic-compatible butadiene rubber: 100 parts butadiene rubber matrix, 50 parts carbon black, 60 parts mica powder, 30 parts glass powder, 20 parts talc, 10 parts borax, and 10 parts vulcanizing agent; the following components are used to make ceramic-compatible nitrile rubber: 100 parts nitrile rubber matrix, 40 parts silica, 70 parts mica powder, 40 parts glass powder, 20 parts alumina, 10 parts vulcanizing agent, and 10 parts plasticizer.

[0042] Example 1: (1) Functional fibers with a core-sheath structure are prepared using a composite spinning process: (11) The skin material (polypropylene) and core material (ceramicable EPDM rubber) slices were placed in a 65°C forced-air oven and dried for 5 hours to reduce the moisture content to below 200ppm. Then, the dried skin material and core material were added to separate screw extruders for melting. The skin material was controlled to melt and plasticize at a set temperature of 210°C (the specific temperature curves are: 180°C in the feeding zone, 190°C in the compression zone, 210°C in the homogenization zone, and 210°C in the die head). The core material was controlled to melt and extrude at a low temperature of 110°C (the specific temperature curves are: 70°C in the feeding zone, 90°C in the compression zone, 110°C in the homogenization zone, and 110°C in the die head) to obtain the core melt and skin melt. The high-precision metering pumps at the outlets of the two extruders stably transported the skin melt and core melt to the composite spinning assembly at a constant skin-to-core ratio of 20:80. (12) In the composite spinning assembly, the skin melt is guided by the distribution plate to form a surrounding tubular fluid, while the core melt is guided to the central channel of the tubular fluid, and the tubular skin fluid and the core fluid in the central channel are combined in the composite cavity to form a pre-formed fluid with a skin-core structure. (13) The pre-formed fluid is extruded through a concentric core-sheath composite spinneret with an aperture of 0.3 mm and an aspect ratio of 2:1 under a spinning pressure of 1.0 MPa. After being cooled and solidified by annular air blowing, a functional fiber with a core-sheath structure is obtained; wherein, the air temperature is 18℃ and the air velocity is 0.4 m / s; (2) 10 kg of ceramic fibers (alumina fibers) with a length of 4.5~5.5 mm and a diameter of 1.5~2.5 μm and 4.3 kg of the above functional fiber bundles were decomposed in a decomposition machine with a rotation speed of 950 r / min for 8 min to obtain a mixed fiber slurry with a slurry concentration of 1.0%; The pH of the mixed fiber pulp was adjusted to 2.5 using dilute sulfuric acid, and then water was added to form a wet substrate at a papermaking concentration of 0.20 wt‰, following the wet papermaking method. The wet substrate was dried to a constant weight by gradually increasing the temperature to 140°C, and then cured at 160°C for 10 minutes to obtain ultra-thin high-strength ceramic fiber paper. During the drying process, the temperature was first increased from room temperature (25°C) to 90°C at a rate of 50°C / min, and then increased from 90°C to 140°C at a rate of 10°C / min.

[0043] Example 2: Example 2 is basically the same as Example 1, except that in step (1), the outer layer of the functional fiber is polyethylene and the core layer is ceramicizable styrene-butadiene rubber. The amount added and the ratio of the outer layer to the core are the same as in Example 1. The outer layer material is controlled to melt and plasticize at a set temperature of 240°C (the specific temperature curve is: feeding zone 220°C, compression zone 230°C, homogenization zone 240°C, die head 240°C). The core layer material is controlled to melt and extrude at a low temperature of 120°C (the specific temperature curve is: feeding zone 100°C, compression zone 110°C, homogenization zone 120°C, die head 120°C).

[0044] Example 3: Example 3 is basically the same as Example 1, except that in step (1), the outer layer of the functional fiber is copolyamide and the core layer is ceramicizable cis-butadiene rubber. The amount added and the ratio of the outer layer to the core are the same as in Example 1. The outer layer material is controlled to melt and plasticize at a set temperature of 260°C (the specific temperature curve is: feeding zone 240°C, compression zone 250°C, homogenization zone 260°C, die head 260°C). The core layer material is controlled to melt and extrude at a low temperature of 130°C (the specific temperature curve is: feeding zone 110°C, compression zone 120°C, homogenization zone 130°C, die head 130°C).

[0045] Example 4: Example 4 is basically the same as Example 1, except that in step (1), the outer layer of the functional fiber is copolyester and the core layer is ceramic nitrile rubber. The amount added and the ratio of the outer layer to the core are the same as in Example 1. The outer layer material is controlled to melt and plasticize at a set temperature of 260°C (the specific temperature curve is: feeding zone 240°C, compression zone 250°C, homogenization zone 260°C, die head 260°C). The core layer material is controlled to melt and extrude at a low temperature of 130°C (the specific temperature curve is: feeding zone 110°C, compression zone 120°C, homogenization zone 130°C, die head 130°C).

[0046] Example 5: Example 5 is basically the same as Example 1, except that in step (1), the mass ratio of the skin material to the core material is 70:30.

[0047] Example 6: Example 6 is basically the same as Example 1, except that in step (1), the mass ratio of the skin material to the core material is 15:85.

[0048] Example 7: Example 7 is basically the same as Example 1, except that in step (2), the amount of functional fiber added is 3 kg.

[0049] Example 8: Example 8 is basically the same as Example 1, except that in step (2), the amount of functional fiber added is 6 kg.

[0050] Comparative Example 1: 10 kg of ceramic fibers (alumina fibers) with a length of 4.5~5.5 mm and a diameter of 1.5~2.5 μm and 4.3 kg of inorganic binder (sodium silicate) were decomposed in a decomposition machine at a speed of 950 r / min for 8 min to obtain a mixed fiber slurry with a slurry concentration of 1.0%. The pH of the mixed fiber pulp was adjusted to 2.5 using dilute sulfuric acid, and then water was added to form a wet substrate at a papermaking concentration of 0.20 wt‰, following the wet papermaking method. The wet substrate was dried to a constant weight by gradually increasing the temperature to 140°C, and then cured at 160°C for 10 minutes to obtain ultra-thin high-strength ceramic fiber paper. During the drying process, the temperature was first increased from room temperature (25°C) to 90°C at a rate of 50°C / min, and then increased from 90°C to 140°C at a rate of 10°C / min.

[0051] Comparative Example 2 Comparative Example 2 is basically the same as Example 1, except that in step (2), the functional fiber is replaced with the same mass of polypropylene fiber.

[0052] The performance of the ultrathin high-strength ceramic fiber paper samples provided in the examples and comparative examples was tested, and the test results are shown in Table 1 below: Table 1 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 method for preparing ultrathin high-strength ceramic fiber paper, characterized in that, The preparation method includes the following steps: (1) A functional fiber with a core-sheath structure is prepared by a composite spinning process; wherein the sheath of the functional fiber is a thermoplastic polymer material and the core is a ceramic polymer material; (2) The functional fiber and ceramic fiber are dispersed and mixed to obtain a mixed fiber slurry, and the mixed fiber slurry is wet-formed, and then dried and cured to obtain the ultra-thin high-strength ceramic fiber paper.

2. The preparation method according to claim 1, characterized in that, In step (1), the outer layer of the functional fiber is one of polyethylene, copolyamide, or copolyester, and the core layer is one of ceramic-compatible styrene-butadiene rubber, ceramic-compatible butadiene rubber, ceramic-compatible silicone rubber, ceramic-compatible nitrile rubber, ceramic-compatible EPDM rubber, or ceramic-compatible polyolefin; and / or In the functional fiber, the sheath layer accounts for 20-25 wt%, and the core layer accounts for 75-80 wt%.

3. The preparation method according to claim 1, characterized in that, The functional fiber with a core-sheath structure is prepared in the following manner: (11) Add the skin layer material and the core layer material into separate screw extruders for melting to obtain core layer melt and skin layer melt; (12) In the composite spinning assembly, the skin melt is guided by the distribution plate to form a surrounding tubular fluid, while the core melt is guided to the central channel of the tubular fluid, and the tubular skin fluid and the core fluid in the central channel are combined in the composite cavity to form a pre-formed fluid with a skin-core structure. (13) The preformed fluid is extruded through a concentric core-sheath composite spinneret and cooled and solidified to obtain the functional fiber with a core-sheath structure.

4. The preparation method according to claim 3, characterized in that, In step (11), the melt extrusion temperature of the skin material is 200~260℃, and the melt extrusion temperature of the core material is 100~150℃. In step (13), the extrusion pressure is 0.8~1.2MPa; the orifice diameter of the concentric circle core-shell composite spinneret is 0.2~0.4mm, and the length-to-diameter ratio is 2:1; Preferably, the cooling and curing method is ring-blowing cooling, with an air temperature of 16~19℃ and an air speed of 0.3~0.5m / s.

5. The preparation method according to claim 1, characterized in that, In step (2), the ceramic fiber is one of alumina fiber, mullite fiber, or aluminosilicate fiber; and / or The ceramic fibers have a diameter of 0.3~3μm, a length of 0.3~6mm, and a slag ball content of ≤0.5%.

6. The preparation method according to claim 1, characterized in that, In step (2), the mass ratio of functional fiber to ceramic fiber is (0.4~0.5):

1.

7. The preparation method according to claim 1, characterized in that, In step (2), the concentration of the mixed fiber slurry is 0.5~1.5wt%, and the pH value is 2.0~3.

0.

8. The preparation method according to claim 1, characterized in that, In step (2), during the wet molding process, the dehumidification vacuum degree is 0.03~0.05Mpa, and the forced vacuum degree is 0.04~0.06Mpa.

9. The preparation method according to claim 1, characterized in that, In step (2), the drying temperature is 140~160℃, the curing temperature is 150~170℃, and the time is 10~15min; Preferably, a two-stage gradient heating method is used for drying; the temperature of the first stage is 80~100℃ and the heating rate is 40~60℃ / min, and the temperature of the second stage is 120~140℃ and the heating rate is 10~15℃ / min.

10. An ultra-thin, high-strength ceramic fiber paper, characterized in that, Prepared by the method according to any one of claims 1 to 9; The ceramic fiber paper has a thickness of 0.2~0.5mm, a temperature resistance of 800~1200℃, and a tensile strength of 0.25~0.50kN / m.

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