Skin-core type polyester aerogel fiber and preparation method thereof

Abstract

The invention belongs to the technical field of polyester aerogel fibers, and discloses a skin-core type polyester aerogel fiber and a preparation method thereof.The monofilament of the skin-core type polyester aerogel fiber is of a skin-core structure, base materials of a skin layer and a core layer are polyester, silicon-containing polyester aerogel particles of a core-shell structure are dispersed in the core layer, and the silicon-containing polyester aerogel particles of a core-shell structure are dispersed in the core layer. The mass of the silicon-containing polyester aerogel particles with the core-shell structure in the core layer is 25-45% of the mass of polyester, and the preparation process of the silicon-containing polyester aerogel particles with the core-shell structure comprises the following steps: soaking hydrophilic silicon dioxide aerogel in an ethanol solution, mixing the modified hydrophilic silicon dioxide aerogel, a silane coupling agent, PTA, ethylene glycol, water and other substances, heating, and carrying out ultrasonic dispersion to obtain the silicon-containing polyester aerogel particles with the core-shell structure. Carrying out esterification reaction and condensation polymerization reaction; the preparation method comprises the following steps: respectively preparing a core layer raw material and a skin layer raw material, and performing skin-core composite spinning to obtain the skin-core type polyester aerogel fiber. The heat-insulating material has good heat-insulating property and mechanical property at the same time.

Description

TECHNICAL FIELD

[0001] The present application belongs to the technical field of polyester aerogel fibers, and relates to a skin-core type polyester aerogel fiber and a preparation method thereof. BACKGROUND

[0002] With the aggravation of global climate problems, the increase in the cost of space heating and cooling and its impact on the environment, researchers are increasingly focusing on the personal thermal management function of textiles. In cold environments, traditional cold-weather clothing often uses down, cotton and other filling materials, but such materials have certain limitations in terms of warmth and comfort. With further research, aerogel textiles have gradually become a research hotspot for personal thermal management textiles due to their advantages of being lightweight, having good warmth retention and strong air permeability.

[0003] Silica aerogel is a lightweight porous new material with a three-dimensional nanometer grid structure, and has the advantages of high surface area, high porosity, low thermal conductivity and low density. Polyester fibers have the advantages of high strength, good wear resistance and good elasticity, but their performance in terms of thermal insulation and the like is lacking. The combination of the two can make polyester fibers have the characteristics of lightness, thermal insulation and the like. The current production method of silica polyester aerogel fibers mainly uses in-situ blending and post-treatment and the like, but with the addition of silica, the aerogel particles are prone to agglomeration, resulting in poor melt flowability of the chips and failing to meet the requirements of the spinning process. Moreover, the two are prone to uneven dispersion, poor interfacial bonding and damage to the aerogel structure during mixing, resulting in poor mechanical properties and thermal insulation of the fibers.

[0004] In the document "Thermal Insulation PET / SiO2 Aerogel Composite Fiber Preparation and Thermal Conductivity Research[D]. 2023.", silica aerogel is added to PET by melt blending and adding carbon tetrachloride as a dispersant to prepare silica polyester aerogel fibers. This method reduces the falling of dust, but with the addition of SiO2 aerogel, the mechanical properties of the fibers are deteriorated, and carbon tetrachloride as a dispersion medium can harm the environment and the body.

[0005] Patent application No. CN117430922A discloses a silica-containing aerogel polyester masterbatch, a preparation method thereof and a silica-containing aerogel polyester fiber. However, the silica content of the silica-containing aerogel polyester masterbatch is ≤8%, and the interfacial shear strength is ≤5MPa, which is difficult to be used as the core material of high-performance skin-core fibers, and is prone to problems such as aerogel particle shedding and fiber breakage. Moreover, some aerogel particles are exposed on the surface of the fibers, and the structure of the aerogel changes over time due to the erosion of moisture and oxygen in the air, thereby affecting the thermal insulation effect.

[0006] Therefore, it is necessary to provide a skin-core type polyester aerogel fiber and a preparation method thereof to solve the above problems, which is of great significance. SUMMARY

[0007] The present application aims to solve the problems existing in the prior art and provide a skin-core type polyester aerogel fiber and a preparation method thereof.

[0008] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0009] A skin-core type polyester aerogel fiber, a single filament having a skin-core structure;

[0010] The base material of the skin layer is polyester;

[0011] The base material of the core layer is polyester, and the core layer is dispersed with core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 25%-45% of the mass of the polyester, and when the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is >45% of the mass of the polyester, the flowability will be lost;

[0012] The preparation steps of the core-shell structure silicon-containing polyester aerogel particles are as follows:

[0013] (a) soaking the hydrophilic silica aerogel in an ethanol solution to activate the surface hydroxyl group, thereby obtaining modified hydrophilic silica aerogel;

[0014] (b) mixing the modified hydrophilic silica aerogel, silane coupling agent, PTA, ethylene glycol, water and other substances, and heating to hydrolyze the silane coupling agent, and the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel at one end to form a covalent bond, and reacts with one end of PTA and / or ethylene glycol at the other end to form a covalent bond, wherein the other substances include an initiator (such as ammonium persulfate) and a catalyst;

[0015] Taking the silane coupling agent KH560 as an example, the reaction process of step (b) is described, and the reaction equation is as follows:

[0016] ① Hydrolysis of the silane coupling agent, and the reaction equation is as follows:

[0017] (CH3O)3Si-(CH2)3-O-CH2-CH(O)CH2+3H2O→(HO)3Si-(CH2)3-O-CH2-CH(O)CH2+3CH3OH;

[0018] ② Reaction of one end of the hydrolyzed silane coupling agent with the modified hydrophilic silica aerogel, and the reaction equation is as follows:

[0019] n(HO)3Si-(CH2)3-O-CH2-CH(O)CH2+(HO)n-SiO2→SiO2-[Si-(CH2)3-O-CH2-CH(O)CH2] n+nH2O;

[0020] The other end of the hydrolyzed silane coupling agent reacts with one end of PTA and / or ethylene glycol, and part of the reaction equation is as follows:

[0021] SiO2-[Si-(CH2)3-O-CH2-CH(O)CH2] n +nHO-CH2CH2-OH→SiO2-[Si-(CH2)3-O-CH2-CH(OH)-CH2-O-CH2CH2-OH] n +nH2O;

[0022] (c) Adjust the reaction conditions so that PTA and ethylene glycol undergo esterification and polycondensation reactions in turn;

[0023] In this process, the product of step (b) also reacts with the polyester segment (the polycondensation product of PTA and ethylene glycol, PET), and the reaction equation is as follows:

[0024] SiO2-[Si-(CH2)3-O-CH2-CH(OH)-CH2-O-CH2CH2-OH] n +nHO-PET→SiO2-[Si-(CH2)3-O-CH2-CH(OH)-CH2-O-CH2CH2-O-PET] n + nH2O;

[0025] After the polyester segment is connected to the modified hydrophilic silica aerogel through the silane coupling agent, the polyester segments are self-entangled to form a physical entangled network, and finally a uniform polyester shell layer is formed on the surface of the silica aerogel;

[0026] The shear strength of the core-shell structure silicon-containing polyester aerogel particles is not less than 9.4 MPa, the average coating rate of the polyester shell layer on the modified hydrophilic silica aerogel is not less than 68%, and the thermal conductivity is not higher than 0.025 W / (m·K).

[0027] As a preferred technical solution:

[0028] A skin-core polyester aerogel fiber as described above, the cross-section of the single filament is circular, and the skin-core structure is a positive skin-core structure; the mass ratio of the skin layer to the core layer is 4:6; the base material of the skin layer is PET or low-melting-point PET, and the melting point of the low-melting-point PET is 110-130℃; the base material of the core layer is PET; and 0-20wt% of functional powder (antibacterial and antiviral powder, antistatic powder, light-heat conversion powder, flame-retardant powder, phase change material, conductive and thermal conductive material, etc.) is dispersed in the skin layer.

[0029] A core-sheath type polyester aerogel fiber as described above, wherein the average particle size of the hydrophilic silica aerogel is 1-3 µm, the porosity is greater than 90%, and the bulk density is not more than 28.5 g / L;

[0030] The silane coupling agent is one or more of an epoxy silane coupling agent (such as KH560, A-187), an amino silane coupling agent (such as KH550, A-1100), a methacryloyloxy silane coupling agent (such as KH570, A-174), a vinyl silane coupling agent (such as A-151, A-172), and 3-carboxypropyltrimethoxysilane.

[0031] A core-sheath type polyester aerogel fiber as described above, wherein in step (a), the water content of the ethanol solution (water content = mass of water / mass of ethanol solution × 100%) is 3-15 wt%, the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:10-20, the temperature of the soaking is 25-30℃, and the soaking time is 2-3 h;

[0032] In step (b), in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:6-10, the molar ratio of ethylene glycol to PTA is 1-3:1, the mass of the silane coupling agent is 1-15% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.1-1% of the total mass of PTA and ethylene glycol, and the mass of the catalyst is 0.01-0.05% of the total mass of PTA and ethylene glycol; during the heating process, acetic acid is used to adjust the pH value of the system to 4-5 to control the hydrolysis rate of the silane coupling agent and the dynamic bonding rate of the silane coupling agent and the polyester, the heating temperature is 60-100℃, and the heating time is 5-6 h;

[0033] In step (b), the other substances also include an amphiphilic solvent (such as a tertiary amine oxide); in the mixed system, the mass of the amphiphilic solvent is 3-20% of the total mass of PTA and ethylene glycol; the amphiphilic solvent can effectively reduce the interfacial tension between PTA, ethylene glycol, and the modified hydrophilic silica aerogel, and enhance the hydrophilicity of the system;

[0034] In step (b), the process of mixing the modified hydrophilic silica aerogel, the silane coupling agent, PTA, ethylene glycol, water, and other substances is as follows: under ultrasonic assistance, the modified hydrophilic silica aerogel is dispersed in the mixed solution of PTA, ethylene glycol, and water, and then the silane coupling agent and other substances are added, wherein the ultrasonic frequency is 30-50 kHz; in the early stage of polymerization, the silica aerogel is forcibly dispersed by high-frequency ultrasound, which can effectively avoid the agglomeration of the silica aerogel;

[0035] In step (c), the reaction conditions of the esterification reaction are: temperature 240-260℃, pressure 0.1 MPa, time 2-3h; and the conditions of the polycondensation reaction are: temperature 270-290℃, pressure 100 Pa or less, time 3-4h.

[0036] The preparation steps of the core-shell structure of the silicon-containing polyester aerogel particles also include step (d): after the reaction system of step (c) is cooled to 120-150℃, a bifunctional crosslinking agent (such as divinylbenzene) is added thereto and kept for 1-2h; the mass addition amount of the bifunctional crosslinking agent in step (d) is 0.5-2% of the total mass of PTA and ethylene glycol in step (b); the purpose of step (d) is to initiate covalent crosslinking of the bifunctional crosslinking agent with the polyester, to build a stable three-dimensional chemical network in the polyester shell layer, to cooperate with the physical entanglement network formed between the polyester segments by self-entanglement to form a double network, to enhance the structural stability of the polyester shell layer, to avoid pore collapse or deformation of the polyester shell layer due to water absorption or external pressure in the subsequent use process, and to greatly enhance the practicability and durability of the material.

[0037] The preparation steps of the core-shell structure of the silicon-containing polyester aerogel particles also include step (e): after the solid product of step (d) is replaced in a displacement agent (such as ethanol or n-hexane), it is taken out, dried at 25℃ for 1-2h, dried at 50℃ for 2-3h, and dried at 80℃ for 2-3h; the present application uses solvent replacement combined with gradient temperature drying to replace the traditional supercritical drying process, greatly reducing the equipment requirements and energy consumption.

[0038] The skin-core polyester aerogel fiber according to any one of the above has a specification of 75-150D / 48-96F, a density of 0.14-0.18g / cm3, a characteristic viscosity of 0.65±0.05dL / g, a breaking strength of ≥2.22cN / dtex, an elongation at break of 15-35%, a thermal conductivity of 0.028-0.035W / (m·K), and a pore retention rate of the core-shell structure of the silicon-containing polyester aerogel particles of >85%.

[0039] The present application also provides a method for preparing the skin-core polyester aerogel fiber according to any one of the above, wherein after the core layer raw material and the skin layer raw material are prepared respectively, skin-core composite spinning is performed, and the skin-core polyester aerogel fiber is obtained.

[0040] As a preferred technical solution:

[0041] The method according to the above has the following preparation steps for the core layer raw material:

[0042] (i) the dried core-shell structure of the silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO (N-methyl morpholine-N-oxide), antioxidant are added into a high-speed mixer, and stirred at 80-100℃ at a speed of 300-500r / min for 30-60min to obtain a premix, wherein the mass of the silane coupling agent, NMMO and antioxidant is 5wt%, 3wt% and 1wt% of the mass of the core-shell structure of the silicon-containing polyester aerogel particles respectively;

[0043] (ii) the premix is added into a twin-screw extruder together with polyester, and after melt blending, extruded and pelletized; the temperature of each zone of the twin-screw extruder is: zone 1 260-270℃, zone 2 270-280℃, zone 3 280-290℃, the temperature of the extruder is 280-285℃; the screw rotation speed is 100-200r / min;

[0044] (iii) the pellets are soaked in n-hexane for 1.5-2.5h to replace residual moisture, and after void protection treatment, collapse during drying is avoided;

[0045] (iv) the pellets are gradient dried to make the core-shell structure of the silicon-containing polyester aerogel particles have a pore retention rate of >85%, the gradient drying is that first dried at 75-85℃ for 1-2h, then dried at 95-105℃ for 1-2h, and then dried at 115-125℃ for 1-2h;

[0046] (v) the pellets are vacuum dried at 90-110℃ for 4-6h (vacuum degree ≤-0.09MPa), and the water content is controlled to be ≤0.05wt%, to obtain the core layer raw material;

[0047] When the functional powder is not contained in the skin layer, the polyester is directly used as the skin layer raw material; when the functional powder is contained in the skin layer, the polyester is melt blended with the functional powder to pelletize, to obtain the skin layer raw material.

[0048] The process flow of the skin-core composite spinning is as follows: melting→ metering→ extrusion→ monomer suction→ side air cooling→ oiling for bundling→ first stretching→ second stretching→ third stretching→ setting→ winding into a shape, according to the method described above.

[0049] The process parameters of the skin-core composite spinning include: spinning temperature 260-300℃, spinning speed 800-1200m / min, slow cooling zone temperature 80-100℃, first stretching (i.e. pre-stretching) temperature 55-70℃, first stretching (i.e. pre-stretching) multiple 1.8-2.2, second stretching (i.e. main stretching) temperature 120-135℃, second stretching (i.e. setting stretching) multiple 2.5-3.0, third stretching temperature 95-110℃, third stretching multiple 0.9-1.05, setting temperature 90-105℃, setting time 8-15min, total stretching multiple = pre-stretching × main stretching.

[0050] Advantages:

[0051] (1) The present application solves the problem of poor organic-inorganic interface compatibility in the preparation process of polyester aerogel fibers by adding core-shell structure silicon-containing polyester aerogel particles with high shear stress, reduces the damage of mechanical stirring in the blending process to the structure of aerogel particles; at the same time, the core-shell structure silicon-containing polyester aerogel particles are coated in the polyester, avoiding the damage of wet oxygen to the structure of aerogel, ensuring the heat insulation effect, and avoiding the use of toxic aerogel dispersant and high-cost drying technology.

[0052] (2) The present application provides flexible support by taking polyester as the skin layer, and coats the core-shell structure silicon-containing polyester aerogel particles in the core layer, avoiding the brittle fracture of aerogel fibers, solving the problems of low fiber strength, cracks and easy fracture of conventional blended aerogel fibers due to uneven particle distribution and poor interface compatibility, and making it have wide application prospect in the fields of ultra-light thermal insulation clothing, aerospace lightweight materials, new energy and the like. BRIEF DESCRIPTION OF DRAWINGS

[0053] Figure 1 The transmission electron micrograph of the core-shell structure silicon-containing polyester aerogel particles prepared in Example A1 of the present application;

[0054] Figure 2 The SEM graph of the skin-core type polyester aerogel fiber prepared in Example B3 of the present application. DETAILED DESCRIPTION

[0055] The present application will be further described in conjunction with specific embodiments. It should be understood that these embodiments are only used to illustrate the present application and not to limit the scope of the present application. In addition, it should be understood that after reading the content taught by the present application, those skilled in the art can make various modifications or changes to the present application, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

[0056] In order to fully disclose the properties of the substances used in each example and comparative example, the manufacturer and brand of the substance are written, and other products of other manufacturers and brands that meet the definition of the present application are also feasible.

[0057] The following are the manufacturers and brands of silane coupling agents in each example:

[0058] Vinyl silane coupling agent A-151: the manufacturer is Guangzhou Longkai Chemical Co., Ltd.;

[0059] 3-carboxypropyltrimethoxysilane: the manufacturer is Wuhan Kemik Biological Medicine Technology Co., Ltd.;

[0060] Epoxy silane coupling agent KH560: the manufacturer is Sinopharm Chemical Reagent Co., Ltd., the Sinopharm code is 30213868, and the specification is KH560 (Shanghai test);

[0061] Amino silane coupling agent KH550: the manufacturer is Sinopharm Chemical Reagent Co., Ltd., the Sinopharm code is 30213867, and the specification is KH550 (Shanghai test);

[0062] Methacryloxy silane coupling agent KH570: the manufacturer is Sinopharm Chemical Reagent Co., Ltd., the Sinopharm code is 30213869, and the specification is KH570 (Shanghai test);

[0063] The test methods of the relevant performance indicators in the following examples and comparative examples are as follows:

[0064] Breaking strength: the core-sheath structure aerogel fibers prepared in examples B1-B9 and each comparative example are respectively taken as samples, and then the breaking strength of the samples is determined according to the standard of GB / T 14344-2022 “Chemical fibers - Filament tensile property test method”.

[0065] Breaking elongation: the core-sheath structure aerogel fibers prepared in examples B1-B9 and each comparative example are respectively taken as samples, and then the breaking elongation of the samples is determined according to the standard of GB / T 14344-2022 “Chemical fibers - Filament tensile property test method”.

[0066] Thermal conductivity: the core-sheath structure aerogel fibers prepared in examples B1-B9 and each comparative example are respectively taken as samples, and then the thermal conductivity of the samples is determined according to the standard of GB / T 10294-2008 “Determination of steady-state thermal resistance and related properties of thermal insulating materials - Guarded hot plate method”.

[0067] Example A1

[0068] A preparation method of a core-shell structure silicon-containing polyester aerogel particle, the steps are as follows:

[0069] (1) Preparation of raw materials;

[0070] Hydrophilic silica aerogel: the average particle size is 1 µm, the porosity is 93%, and the bulk density is 22 g / L;

[0071] Ethanol solution: the water content is 5 wt%;

[0072] Ethylene glycol;

[0073] PTA (purified terephthalic acid);

[0074] Water;

[0075] Silane coupling agent: vinyl silane coupling agent A-151;

[0076] initiator: ammonium persulfate;

[0077] catalyst: antimony ethylene glycol;

[0078] amphiphilic solvent: N-methylmorpholine-N-oxide;

[0079] acetic acid;

[0080] difunctional crosslinking agent: divinylbenzene;

[0081] displacement agent: n-hexane;

[0082] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, ultrasonically dispersed at a frequency of 40 kHz for 0.5 h, and vacuum dried after refluxing for 2.5 h to activate the surface hydroxyl groups, to obtain modified hydrophilic silica aerogel; wherein the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:15, the soaking temperature is 28℃, the soaking time is 2.6 h, the vacuum drying temperature is 60℃, and the vacuum drying time is 2 h;

[0083] (3) The modified hydrophilic silica aerogel is dispersed in a mixture of PTA, ethylene glycol and water under the assistance of ultrasonic waves at a frequency of 40 kHz, and then the silane coupling agent, initiator, catalyst and amphiphilic solvent are added and ultrasonically dispersed for 30 min, and the silane coupling agent is hydrolyzed under the protection of nitrogen at a temperature of 90℃ for 5 h, so that one end of the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel to form a covalent bond, and the other end reacts with one end of PTA and / or ethylene glycol to form a covalent bond; wherein in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:6, the molar ratio of ethylene glycol to PTA is 1.5:1, the mass of the silane coupling agent is 5% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.5% of the total mass of PTA and ethylene glycol, the mass of the catalyst is 0.01% of the total mass of PTA and ethylene glycol, and the mass of the amphiphilic solvent is 20% of the total mass of PTA and ethylene glycol, and the pH value of the system is adjusted to 4.5 during the heating process;

[0084] (4) The reaction system of step (3) is first esterified at a temperature of 240℃ and a pressure of 0.1 MPa for 3 h, and then subjected to polycondensation reaction at a temperature of 270℃ and a pressure of 95 Pa for 3.5 h;

[0085] (5) After the reaction system of step (4) is cooled to 150℃, a difunctional crosslinking agent is added and incubated for 1.5 h; wherein the mass of the difunctional crosslinking agent is 1% of the total mass of PTA and ethylene glycol in step (3);

[0086] (6) After the solid product of step (5) is subjected to replacement in a replacement agent, it is taken out, dried at 25°C for 2h, at 50°C for 3h, and at 80°C for 3h in sequence, and a core-shell structure silicon-containing polyester aerogel particle is prepared.

[0087] The shear strength of the finally prepared core-shell structure silicon-containing polyester aerogel particle (whose electron microscope image is shown in Figure 1 ) is 12.5 MPa, the average coating rate of the modified hydrophilic silica aerogel by the polyester shell layer is 92%, and the thermal conductivity is 0.022 W / (m·K).

[0088] Example A2

[0089] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, the steps are as follows:

[0090] (1) Preparation of raw materials;

[0091] Hydrophilic silica aerogel: average particle size 3 µm, porosity 93%, bulk density 22 g / L;

[0092] Ethanol solution: water content 5 wt%;

[0093] Ethylene glycol;

[0094] PTA (pure terephthalic acid);

[0095] Water;

[0096] Silane coupling agent: 3-carboxypropyltrimethoxysilane;

[0097] Initiator: ammonium persulfate;

[0098] Catalyst: antimony ethylene glycol;

[0099] Amphiphilic solvent: N-methylmorpholine-N-oxide;

[0100] Acetic acid;

[0101] Bifunctional crosslinking agent: divinylbenzene;

[0102] Replacement agent: n-hexane;

[0103] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, first ultrasonically dispersed at a frequency of 40 kHz for 0.8h and refluxed for 2.6h, and then vacuum dried to activate the surface hydroxyl groups to obtain a modified hydrophilic silica aerogel; wherein the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:16, the soaking temperature is 28°C, the soaking time is 2.2h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2h;

[0104] (3) Under the assistance of ultrasonic waves with a frequency of 40 kHz, the modified hydrophilic silica aerogel is dispersed in a mixture of PTA, ethylene glycol and water, and then a silane coupling agent, an initiator, a catalyst and an amphiphilic solvent are added and ultrasonically dispersed for 30 min. The mixture is heated at 90°C under nitrogen protection for 5 h to hydrolyze the silane coupling agent, and the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel at one end to form a covalent bond and reacts with one end of PTA and / or ethylene glycol at the other end to form a covalent bond; wherein in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:10, the molar ratio of ethylene glycol to PTA is 2:1, the mass of the silane coupling agent is 10% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.3% of the total mass of PTA and ethylene glycol, the mass of the catalyst is 0.05% of the total mass of PTA and ethylene glycol, and the mass of the amphiphilic solvent is 8% of the total mass of PTA and ethylene glycol; and the pH value of the system is adjusted to 4.3 during the heating process;

[0105] (4) The reaction system of step (3) is first esterified at a temperature of 250°C and a pressure of 0.1 MPa for 2 h, and then subjected to polycondensation reaction at a temperature of 280°C and a pressure of 90 Pa for 4 h;

[0106] (5) After the reaction system of step (4) is cooled to 150°C, a bifunctional crosslinking agent is added thereto and incubated for 1.5 h; wherein the mass of the bifunctional crosslinking agent added is 0.8% of the total mass of PTA and ethylene glycol of step (3);

[0107] (6) After the solid product of step (5) is subjected to displacement in a displacement agent, it is taken out, dried at 25°C for 2 h, at 50°C for 3 h, and at 80°C for 3 h in sequence, to obtain the core-shell structure silicon-containing polyester aerogel particles.

[0108] The final core-shell structure silicon-containing polyester aerogel particles have a shear strength of 12.6 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 93%, and a thermal conductivity of 0.021 W / (m·K).

[0109] Example A3

[0110] A method for preparing core-shell structure silicon-containing polyester aerogel particles, comprising the following steps:

[0111] (1) Preparation of raw materials;

[0112] Hydrophilic silica aerogel: average particle size of 2 µm, porosity of 91%, bulk density of 26 g / L;

[0113] Ethanol solution: water content of 3 wt%;

[0114] Ethylene glycol;

[0115] PTA (pure terephthalic acid);

[0116] Water;

[0117] Silane coupling agent: epoxy silane coupling agent KH560;

[0118] Initiator: ammonium persulfate;

[0119] Catalyst: ethylene glycol antimony;

[0120] Amphiphilic solvent: N-methyl morpholine-N-oxide;

[0121] Acetic acid;

[0122] Bifunctional crosslinking agent: divinyl benzene;

[0123] Displacement agent: n-hexane;

[0124] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, and the surface hydroxyl groups are activated by ultrasonic dispersion at a frequency of 40 kHz for 1 h and reflux reaction for 2 h followed by vacuum drying, to obtain modified hydrophilic silica aerogel; wherein the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:10, the soaking temperature is 25°C, the soaking time is 2 h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2 h;

[0125] (3) The modified hydrophilic silica aerogel is dispersed in a mixture of PTA, ethylene glycol and water under the assistance of ultrasonic waves at a frequency of 30 kHz, and then the silane coupling agent, initiator, catalyst and amphiphilic solvent are added and mixed and ultrasonic dispersed for 20 min, and the hydrolysis of the silane coupling agent is carried out by heating at a temperature of 60°C under nitrogen protection for 5.5 h, so that one end of the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel to form a covalent bond, and the other end reacts with one end of PTA and / or ethylene glycol to form a covalent bond; wherein in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:9, the molar ratio of ethylene glycol to PTA is 1.3:1, the mass of the silane coupling agent is 1% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 1% of the total mass of PTA and ethylene glycol, the mass of the catalyst is 0.04% of the total mass of PTA and ethylene glycol, and the mass of the amphiphilic solvent is 10% of the total mass of PTA and ethylene glycol, and the pH value of the system is adjusted to 4 during the heating process;

[0126] (4) The reaction system of step (3) is first subjected to esterification reaction at a temperature of 260°C and a pressure of 0.1 MPa for 2 h, and then subjected to polycondensation reaction at a temperature of 290°C and a pressure of 85 Pa for 3 h;

[0127] (5) After the reaction system of step (4) is cooled to 120°C, a bifunctional crosslinking agent is added thereto and incubated for 1 h; wherein the mass addition amount of the bifunctional crosslinking agent is 0.5% of the total mass of PTA and ethylene glycol of step (3);

[0128] (6) After the solid product of step (5) is replaced in a replacement agent, it is taken out, dried at 25°C for 1 h, at 50°C for 2 h, and at 80°C for 2 h in sequence, and a core-shell structure silicon-containing polyester aerogel particle is prepared.

[0129] The shear strength of the finally prepared core-shell structure silicon-containing polyester aerogel particle is 12.5 MPa, the average coating rate of the modified hydrophilic silica aerogel by the polyester shell layer is 91.5%, and the thermal conductivity is 0.023 W / (m·K).

[0130] Example A4

[0131] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, the steps are as follows:

[0132] (1) Preparation of raw materials;

[0133] Hydrophilic silica aerogel: average particle size of 3 µm, porosity of 92%, bulk density of 26 g / L;

[0134] Ethanol solution: water content of 15 wt%;

[0135] Ethylene glycol;

[0136] PTA (pure terephthalic acid);

[0137] Water;

[0138] Silane coupling agent: amino silane coupling agent KH550;

[0139] Initiator: ammonium persulfate;

[0140] Catalyst: ethylene glycol antimony;

[0141] Amphiphilic solvent: N-methylmorpholine-N-oxide;

[0142] Acetic acid;

[0143] Bifunctional crosslinking agent: divinylbenzene;

[0144] Replacement agent: ethanol;

[0145] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, and is ultrasonically dispersed at a frequency of 40 kHz for 0.6 h and refluxed for 2.5 h, and then vacuum dried to activate the surface hydroxyl groups, to obtain modified hydrophilic silica aerogel; wherein the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:15, the soaking temperature is 30℃, the soaking time is 2.5 h, the vacuum drying temperature is 60℃, and the vacuum drying time is 2 h;

[0146] (3) The modified hydrophilic silica aerogel is dispersed in a mixture of PTA, ethylene glycol and water under the assistance of ultrasonic waves at a frequency of 40 kHz, and then a silane coupling agent, an initiator, a catalyst and an amphiphilic solvent are added and ultrasonically dispersed for 25 min, and the silane coupling agent is hydrolyzed under heating at a temperature of 100℃ for 6 h in a nitrogen atmosphere, so that one end of the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel to form a covalent bond, and the other end reacts with one end of the PTA and / or ethylene glycol to form a covalent bond; wherein in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:7, the molar ratio of ethylene glycol to PTA is 2.2:1, the mass of the silane coupling agent is 8% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.6% of the total mass of PTA and ethylene glycol, the mass of the catalyst is 0.02% of the total mass of PTA and ethylene glycol, and the mass of the amphiphilic solvent is 12% of the total mass of PTA and ethylene glycol, and the pH value of the system is adjusted to 5 during the heating process;

[0147] (4) The reaction system of step (3) is first esterified at a temperature of 255℃ and a pressure of 0.1 MPa for 2 h, and then subjected to polycondensation reaction at a temperature of 275℃ and a pressure of 95 Pa for 4 h;

[0148] (5) After the reaction system of step (4) is cooled to 130℃, a bifunctional crosslinking agent is added thereto and incubated for 2 h; wherein the mass of the bifunctional crosslinking agent added is 1.2% of the total mass of PTA and ethylene glycol of step (3);

[0149] (6) After the solid product of step (5) is subjected to displacement in a displacement agent, it is taken out, dried at 25℃ for 1.5 h, at 50℃ for 2.5 h, and at 80℃ for 2.5 h, respectively, to obtain the core-shell structure silicon-containing polyester aerogel particles.

[0150] The shear strength of the finally obtained core-shell structure silicon-containing polyester aerogel particles is 12.8 MPa, the average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel is 90%, and the thermal conductivity is 0.022 W / (m·K).

[0151] Example A5

[0152] A method for preparing core-shell structure silicon-containing polyester aerogel particles, substantially the same as embodiment 4, the difference is that no bifunctional crosslinking agent is added in step (5).

[0153] The shear strength of the finally prepared core-shell structure silicon-containing polyester aerogel particles is 9.4 MPa, the average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel is 70%, and the thermal conductivity is 0.020 W / (m·K).

[0154] Example A6

[0155] A method for preparing core-shell structure silicon-containing polyester aerogel particles, the steps are as follows:

[0156] (1) Preparation of raw materials;

[0157] Hydrophilic silica aerogel: average particle size 2 µm, porosity 92%, bulk density 25 g / L;

[0158] Ethanol solution: water content 8 wt%;

[0159] Ethylene glycol;

[0160] PTA (pure terephthalic acid);

[0161] Water;

[0162] Silane coupling agent: methacryloxy silane coupling agent KH570;

[0163] Initiator: ammonium persulfate;

[0164] Catalyst: antimony ethylene glycol;

[0165] Acetic acid;

[0166] Amphiphilic solvent: N-methyl morpholine-N-oxide;

[0167] Bifunctional crosslinking agent: divinyl benzene;

[0168] Displacement agent: ethanol;

[0169] (2) Soak the hydrophilic silica aerogel in the ethanol solution, first ultrasonic dispersion at a frequency of 40 kHz for 0.8 h and reflux reaction for 3 h, then vacuum drying to activate the surface hydroxyl group, to obtain modified hydrophilic silica aerogel; wherein the mass ratio of hydrophilic silica aerogel to ethanol solution is 1:20, the soaking temperature is 26℃, the soaking time is 3 h, the vacuum drying temperature is 60℃, and the vacuum drying time is 2 h;

[0170] (3) under the assistance of ultrasonic waves with a frequency of 50 kHz, the modified hydrophilic silica aerogel is dispersed in a mixture of PTA, ethylene glycol and water, then a silane coupling agent, an initiator, a catalyst and an amphiphilic solvent are added and ultrasonically dispersed for 28 min, and the mixture is heated at 80 ℃ under the protection of nitrogen for 5 h to hydrolyze the silane coupling agent, and the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel at one end to form a covalent bond, and reacts with one end of PTA and / or ethylene glycol at the other end to form a covalent bond; wherein in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:8, the molar ratio of ethylene glycol to PTA is 3:1, the mass of the silane coupling agent is 15% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.1% of the total mass of PTA and ethylene glycol, the mass of the catalyst is 0.03% of the total mass of PTA and ethylene glycol, and the mass of the amphiphilic solvent is 3% of the total mass of PTA and ethylene glycol, and the pH value of the system is adjusted to 4.8 during the heating process;

[0171] (4) the reaction system of step (3) is first esterified at a temperature of 248 ℃ and a pressure of 0.1 MPa for 2.5 h, and then polycondensed at a temperature of 285 ℃ and a pressure of 95 Pa or lower for 3.5 h;

[0172] (5) after the reaction system of step (4) is cooled to 135 ℃, a bifunctional crosslinking agent is added thereto and incubated for 1.8 h; wherein the mass of the bifunctional crosslinking agent added is 2% of the total mass of PTA and ethylene glycol of step (3);

[0173] (6) after the solid product of step (5) is replaced in a displacement agent, it is taken out, dried at 25 ℃ for 1.5 h, at 50 ℃ for 2.5 h, and at 80 ℃ for 2.5 h, respectively, to obtain a core-shell structure silicon-containing polyester aerogel particle.

[0174] The finally prepared core-shell structure silicon-containing polyester aerogel particle has a shear strength of 12.6 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 92%, and a thermal conductivity of 0.025 W / (m·K).

[0175] Example A7

[0176] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, which is basically the same as example 6, except that the silane coupling agent in step (1) is vinyl silane coupling agent A-151.

[0177] The finally prepared core-shell structure silicon-containing polyester aerogel particle has a shear strength of 12.7 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 94%, and a thermal conductivity of 0.022 W / (m·K).

[0178] Example A8

[0179] A method for preparing the core-shell structured silicon-containing polyester aerogel particles is substantially the same as that in Example 6, except that the silane coupling agent in step (1) is composed of 3-carboxypropyltrimethoxysilane and vinyl silane coupling agent A-172 in a mass ratio of 1:1.

[0180] The finally prepared core-shell structured silicon-containing polyester aerogel particles have a shear strength of 12.8 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 92%, and a thermal conductivity of 0.023 W / (m·K).

[0181] Example A9

[0182] A method for preparing the core-shell structured silicon-containing polyester aerogel particles is substantially the same as that in Example 6, except that no bifunctional crosslinking agent is added in step (5).

[0183] The finally prepared core-shell structured silicon-containing polyester aerogel particles have a shear strength of 9.5 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 68%, and a thermal conductivity of 0.022 W / (m·K).

[0184] Comparative Example 1

[0185] A method for preparing the core-shell structured silicon-containing polyester aerogel particles is substantially the same as that in Example A9, except that no silane coupling agent is added in step (3).

[0186] The finally prepared core-shell structured silicon-containing polyester aerogel particles have a shear strength of 6.5 MPa, and an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 46%.

[0187] A comparison between Comparative Example 1 and Example A9 shows that the shear strength of the core-shell structured silicon-containing polyester aerogel particles prepared in Comparative Example 1 decreases, and the coating rate of the polyester shell layer to the modified hydrophilic silica aerogel decreases, because the silane coupling agent can realize chemical bonding between the silica aerogel and the polyester, and at the same time, a double network is constructed inside the polyester shell layer to firmly anchor the silica aerogel core, and the bifunctional crosslinking agent can covalently crosslink with the polyester to further enhance the structural stability inside the polyester shell layer, and finally realize comprehensive improvement of the interfacial performance, while in Comparative Example 1, the lack of both the silane coupling agent and the bifunctional crosslinking agent leads to a decrease in the shear strength of the core-shell structured silicon-containing polyester aerogel particles and a decrease in the coating rate of the polyester shell layer to the modified hydrophilic silica aerogel.

[0188] Example B1

[0189] A method for preparing a core-sheath type polyester aerogel fiber, comprising the following steps:

[0190] (1) Preparation of raw materials;

[0191] Core-shell structure silicon-containing polyester aerogel particles: the core-shell structure silicon-containing polyester aerogel particles prepared in Example A1 were dried at 80℃ for 1.5h;

[0192] Polyester: PET, intrinsic viscosity 0.66dL / g, water content ≤0.4%;

[0193] Silane coupling agent: vinyl silane coupling agent A-151;

[0194] NMMO;

[0195] Antioxidant: manufacturer Qingdao Jidejia New Material Technology Co., Ltd., brand antioxidant AN 215 (B215);

[0196] (2) The dried core-shell structure silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO, antioxidant were added into a high-speed mixer, stirred at 80℃ at a speed of 300r / min for 30min to obtain a premix; wherein the mass of silane coupling agent, NMMO and antioxidant was 5wt%, 3wt% and 1wt% of the mass of the core-shell structure silicon-containing polyester aerogel particles, respectively;

[0197] (3) The premix and polyester were added into a twin-screw extruder, extruded and pelletized after melt blending; wherein the screw speed was 100r / min, the initial melting zone temperature of the twin-screw extruder was 260℃, the melting zone temperature was 270℃, the extruder temperature was 280℃, the water tank temperature was 28℃, and the pelletizer speed was 280r / min;

[0198] (4) The pellets were soaked in n-hexane at 28℃ for 1.5h;

[0199] (5) The soaked pellets were first dried at 75℃ for 1h, then dried at 95℃ for 1h, and then dried at 115℃ for 1h;

[0200] (6) The dried pellets were vacuum dried at 90℃ for 4h to control the water content to be ≤0.05wt%, thereby obtaining the core layer raw material; wherein the vacuum degree during vacuum drying was -0.09;

[0201] (7) The core layer raw material in step (6) was used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) was used as the sheath layer raw material, and then a core-sheath composite process was used for spinning, and the process flow was: melting → metering → extrusion → monomer suction → side blowing cooling → bunching oiling → first stretching → second stretching → third stretching → setting → winding into a shape;

[0202] The process parameters of the core-sheath composite spinning include: spinning temperature 260℃, spinning speed 800m / min, slow cooling zone temperature 80℃, first stretching temperature 55℃, first stretching multiple 1.81, second stretching temperature 120℃, second stretching multiple 2.6, third stretching temperature 95℃, third stretching multiple 0.98, setting temperature 90℃, setting time 8min.

[0203] The cross section of the single fiber of the finally prepared core-sheath polyester aerogel fiber is circular, and the single fiber has a core-sheath structure, and the core-sheath structure is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6;

[0204] The core layer disperses the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 30% of the mass of the polyester;

[0205] The specification of the core-sheath polyester aerogel fiber is 120D / 72F, the density is 0.15g / cm³, the breaking strength is 3.05cN / dtex, the elongation at break is 32%, and the thermal conductivity is 0.029W / (m·K).

[0206] Example B2

[0207] A preparation method of a core-sheath polyester aerogel fiber, the steps are as follows:

[0208] (1) Preparation of raw materials;

[0209] Core-shell structure silicon-containing polyester aerogel particles: the core-shell structure silicon-containing polyester aerogel particles prepared in Example A2 are dried at 80℃ for 2h;

[0210] Polyester: PET, intrinsic viscosity 0.66dL / g, water content ≤0.4%;

[0211] Silane coupling agent: 3-carboxypropyltrimethoxysilane;

[0212] NMMO;

[0213] Antioxidant: the manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., and the brand is Antioxidant AN 215 (B215);

[0214] (2) The dried core-shell structure silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO, antioxidant are added into a high-speed mixer, stirred at 85℃ and 350r / min for 40min to obtain a premix; wherein the mass of the silane coupling agent, NMMO and antioxidant is 5wt%, 3wt% and 1wt% of the mass of the core-shell structure silicon-containing polyester aerogel particles, respectively;

[0215] (3) the premix and the polyester are added into a twin-screw extruder, and after melt blending, extruded and cut into particles; wherein the screw rotation speed is 120 r / min, the initial melting zone temperature of the twin-screw extruder is 263℃, the melting zone temperature is 274℃, the extruder temperature is 281℃, the water tank temperature is 30℃, and the cutting machine rotation speed is 283 r / min;

[0216] (4) the cut pieces are soaked in n-hexane at 28℃ for 1.8 h;

[0217] (5) the soaked cut pieces are first dried at 79℃ for 1.5 h, then dried at 100℃ for 1.5 h, and then dried at 120℃ for 1.5 h;

[0218] (6) the dried cut pieces are vacuum dried at 100℃ for 5 h, with the water content controlled to be ≤0.05wt%, to obtain the core layer raw material; wherein the vacuum degree during vacuum drying is -0.07;

[0219] (7) the core layer raw material in step (6) is used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) is used as the skin layer raw material, and then a skin-core composite process is used for spinning, and the process flow is: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a shape;

[0220] The process parameters of the skin-core composite spinning include: spinning temperature 280℃, spinning speed 950 m / min, slow cooling zone temperature 90℃, first stretching temperature 60℃, first stretching multiple 1.8, second stretching temperature 125℃, second stretching multiple 2.5, third stretching temperature 100℃, third stretching multiple 1.1, setting temperature 95℃, and setting time 10 min.

[0221] The cross section of the single filament in the finally prepared skin-core type polyester aerogel fiber is circular, and the single filament has a skin-core structure, and the skin-core structure is a positive skin-core structure; the mass ratio of the skin layer to the core layer is 4:6;

[0222] The core layer is dispersed with the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 40% of the mass of the polyester;

[0223] The specification of the skin-core type polyester aerogel fiber is 75D / 48F, the density is 0.16 g / cm³, the breaking strength is 2.92 cN / dtex, the breaking elongation is 28%, and the thermal conductivity coefficient is 0.03 W / (m·K).

[0224] Example B3

[0225] A method for preparing a skin-core type polyester aerogel fiber, the steps are as follows:

[0226] (1) Preparation of raw materials;

[0227] Silicon-containing polyester aerogel particles with core-shell structure: the silicon-containing polyester aerogel particles with core-shell structure prepared in Example A3 were dried at 80℃ for 1h;

[0228] Polyester: PET, intrinsic viscosity of 0.66dL / g, water content ≤0.4%;

[0229] Silane coupling agent: epoxy silane coupling agent KH560;

[0230] NMMO;

[0231] Antioxidant: the manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., and the brand is Antioxidant AN 215 (B215);

[0232] (2) The dried silicon-containing polyester aerogel particles with core-shell structure, polyester, silane coupling agent, NMMO, antioxidant were added into a high-speed mixer and stirred at 90℃ at a speed of 400r / min for 50min to obtain a premix; wherein the mass of silane coupling agent, NMMO and antioxidant was 5wt%, 3wt% and 1wt% of the mass of silicon-containing polyester aerogel particles with core-shell structure, respectively;

[0233] (3) The premix was added into a twin-screw extruder together with polyester, and after melt blending, it was extruded and pelletized; wherein the screw speed was 150r / min, the initial melting zone temperature of the twin-screw extruder was 265℃, the melting zone temperature was 275℃, the extruder temperature was 283℃, the water tank temperature was 38℃, and the pelletizer speed was 285r / min;

[0234] (4) The pellets were soaked in n-hexane at 30℃ for 2h;

[0235] (5) The soaked pellets were first dried at 85℃ for 2h, then dried at 105℃ for 2h, and then dried at 125℃ for 2h;

[0236] (6) The dried pellets were vacuum dried at 110℃ for 6h to control the water content to be ≤0.05wt%, thereby obtaining the core layer raw material; wherein the vacuum degree during vacuum drying was -0.08;

[0237] (7) The core layer raw material in step (6) was used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) was used as the skin layer raw material, and then a skin-core composite process was used for spinning, and the process flow was: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a form;

[0238] The process parameters of the core-sheath composite spinning include: spinning temperature 300℃, spinning speed 1100m / min, slow cooling zone temperature 100℃, first stretching temperature 65℃, first stretching multiple 1.5, second stretching temperature 130℃, second stretching multiple 3.0, third stretching temperature 105℃, third stretching multiple 1.05, setting temperature 105℃, setting time 15min.

[0239] The finally prepared core-sheath polyester aerogel fiber (the SEM image of which is shown in Figure 2 ) has a round cross section of the monofilament, and the monofilament has a core-sheath structure which is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6;

[0240] The core layer disperses the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 45% of the mass of the polyester;

[0241] The specification of the core-sheath polyester aerogel fiber is 150D / 72F, the density is 0.18g / cm³, the breaking strength is 2.89cN / dtex, the breaking elongation is 25%, and the thermal conductivity is 0.028W / (m·K).

[0242] Example B4

[0243] A preparation method of a core-sheath polyester aerogel fiber, the steps are as follows:

[0244] (1) Preparation of raw materials;

[0245] Core-shell structure silicon-containing polyester aerogel particles: the core-shell structure silicon-containing polyester aerogel particles prepared in Example A4 are dried at 80℃ for 1.5h;

[0246] Polyester: PET, intrinsic viscosity 0.66dL / g, water content ≤0.4%;

[0247] Silane coupling agent: amino silane coupling agent KH550;

[0248] NMMO;

[0249] Antioxidant: the manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., and the brand is Antioxidant AN 215 (B215);

[0250] (2) The dried core-shell structure silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO, antioxidant are added into a high-speed mixer, stirred at 100℃ at a speed of 500r / min for 60min to obtain a premix; wherein the mass of the silane coupling agent, NMMO and antioxidant is 5wt%, 3wt% and 1wt% of the mass of the core-shell structure silicon-containing polyester aerogel particles, respectively;

[0251] (3) the premix and the polyester are added into a twin-screw extruder, and after melt blending, extruded and cut into particles; wherein the screw rotation speed is 180 r / min, the initial melting zone temperature of the twin-screw extruder is 268℃, the melting zone temperature is 280℃, the extruder temperature is 285℃, the water tank temperature is 25℃, and the cutting machine rotation speed is 287 r / min;

[0252] (4) the cut pieces are soaked in n-hexane at 32℃ for 2.3 h;

[0253] (5) the soaked cut pieces are first dried at 80℃ for 1.6 h, then dried at 98℃ for 1.5 h, and then dried at 118℃ for 1.8 h;

[0254] (6) the dried cut pieces are vacuum dried at 95℃ for 4.5 h, and the water content is controlled to be ≤0.05wt%, thereby obtaining the core layer raw material; wherein the vacuum degree during vacuum drying is -0.06;

[0255] (7) the core layer raw material in step (6) is used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) is used as the skin layer raw material, and then a skin-core composite process is used for spinning, and the process flow is: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a shape;

[0256] The process parameters of the skin-core composite spinning include: spinning temperature 265℃, spinning speed 1200 m / min, slow cooling zone temperature 85℃, first stretching temperature 70℃, first stretching multiple 2.0, second stretching temperature 135℃, second stretching multiple 2.4, third stretching temperature 110℃, third stretching multiple 0.9, setting temperature 95℃, and setting time 10 min.

[0257] The cross section of the single filament in the finally prepared skin-core type polyester aerogel fiber is circular, and the single filament has a skin-core structure, and the skin-core structure is a positive skin-core structure; the mass ratio of the skin layer to the core layer is 4:6;

[0258] The core layer is dispersed with the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 25% of the mass of the polyester;

[0259] The specification of the skin-core type polyester aerogel fiber is 150D / 96F, the density is 0.14 g / cm³, the breaking strength is 3.23 cN / dtex, the breaking elongation is 35%, and the thermal conductivity coefficient is 0.032 W / (m·K).

[0260] Example B5

[0261] A method for preparing a skin-core type polyester aerogel fiber, comprising the following steps:

[0262] (1) Preparation of raw materials;

[0263] Silicon-containing polyester aerogel particles with core-shell structure: the silicon-containing polyester aerogel particles with core-shell structure prepared in Example A5 were dried at 80℃ for 2h;

[0264] Polyester: PET, intrinsic viscosity of 0.66dL / g, water content ≤0.4%;

[0265] Silane coupling agent: amino silane coupling agent KH550;

[0266] NMMO;

[0267] Antioxidant: manufacturer Qingdao Jidejia New Material Technology Co., Ltd., brand antioxidant AN 215 (B215);

[0268] (2) The dried silicon-containing polyester aerogel particles with core-shell structure, polyester, silane coupling agent, NMMO, antioxidant were added into a high-speed mixer and stirred at 95℃ at a speed of 380r / min for 55min to obtain a premix; wherein the mass of silane coupling agent, NMMO and antioxidant was 5wt%, 3wt% and 1wt% of the mass of silicon-containing polyester aerogel particles with core-shell structure, respectively;

[0269] (3) The premix and polyester were added into a twin-screw extruder, and after melt blending, extruded and pelletized; wherein the screw speed was 200r / min, the initial melting zone temperature of the twin-screw extruder was 270℃, the melting zone temperature was 280℃, the extruder temperature was 283℃, the water tank temperature was 30℃, and the pelletizer speed was 290r / min;

[0270] (4) The pellets were soaked in n-hexane at 32℃ for 2.5h;

[0271] (5) The soaked pellets were first dried at 82℃ for 1.8h, then dried at 102℃ for 1.8h, and then dried at 119℃ for 1.2h;

[0272] (6) The dried pellets were vacuum dried at 98℃ for 5h, and the water content was controlled to be ≤0.05wt%, to obtain the core layer raw material; wherein the vacuum degree during vacuum drying was -0.08;

[0273] (7) The core layer raw material in step (6) was used as the core layer raw material, and the polyester (the same as used in the preparation of the core layer raw material) was used as the skin layer raw material, and then a skin-core composite process was used for spinning, and the process flow was: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a form;

[0274] The process parameters of the core-sheath composite spinning include: spinning temperature 270℃, spinning speed 850m / min, slow cooling zone temperature 93℃, first stretching temperature 68℃, first stretching multiple 1.9, second stretching temperature 123℃, second stretching multiple 2.8, third stretching temperature 98℃, third stretching multiple 0.9, setting temperature 100℃, setting time 13min.

[0275] The cross section of the single fiber of the finally prepared core-sheath polyester aerogel fiber is circular, and the single fiber has a core-sheath structure, and the core-sheath structure is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6;

[0276] The core layer disperses the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 30% of the mass of the polyester;

[0277] The specification of the core-sheath polyester aerogel fiber is 150D / 96F, the density is 0.15g / cm³, the breaking strength is 2.98cN / dtex, the breaking elongation is 30%, and the thermal conductivity is 0.03W / (m·K).

[0278] Example B6

[0279] A preparation method of a core-sheath polyester aerogel fiber, the steps are as follows:

[0280] (1) Preparation of raw materials;

[0281] Core-shell structure silicon-containing polyester aerogel particles: the core-shell structure silicon-containing polyester aerogel particles prepared in Example A6 are dried at 80℃ for 1.5h;

[0282] Polyester: PET, intrinsic viscosity 0.66dL / g, water content ≤0.4%;

[0283] Silane coupling agent: methacryloxy silane coupling agent KH570;

[0284] NMMO;

[0285] Antioxidant: the manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., and the brand is Antioxidant AN 215 (B215);

[0286] (2) The dried core-shell structure silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO, antioxidant are added into a high-speed mixer, stirred at 98℃ at a speed of 350r / min for 45min to obtain a premix; wherein the mass of the silane coupling agent, NMMO and antioxidant is 5wt%, 3wt% and 1wt% of the mass of the core-shell structure silicon-containing polyester aerogel particles, respectively;

[0287] (3) The premixed material and polyester are added to a twin-screw extruder, and after melt blending, they are extruded and pelletized; wherein, the screw speed is 160 r / min, the initial melting zone temperature of the twin-screw extruder is 262℃, the melting zone temperature is 278℃, the extruder temperature is 280℃, the water tank temperature is 32℃, and the pelletizer speed is 285 r / min;

[0288] (4) Soak the slices in hexane at 30°C for 2 hours;

[0289] (5) After soaking, the slices were dried at 78℃ for 1.2h, then at 105℃ for 1.6h, and then at 116℃ for 1.8h.

[0290] (6) The dried slices were vacuum dried at 96℃ for 5.5h, and the moisture content was controlled to be ≤0.05wt% to obtain the core material; wherein the vacuum degree during vacuum drying was -0.07;

[0291] (7) Use the core material in step (6) as the core material and polyester (the same polyester used when preparing the core material) as the sheath material. Then use the sheath-core composite process for spinning. The process flow is: melting → metering → extrusion → monomer suction → side blowing cooling → bundling and oiling → first stretching → second stretching → third stretching → shaping → winding.

[0292] The process parameters for core-sheath composite spinning include: spinning temperature 275℃, spinning speed 880m / min, slow cooling zone temperature 95℃, first stretching temperature 65℃, first stretching ratio 1.61, second stretching temperature 132℃, second stretching ratio 2.8, third stretching temperature 96℃, third stretching ratio 0.9, setting temperature 98℃, and setting time 12min.

[0293] The final core-sheath type polyester aerogel fiber has a circular cross-section for the monofilaments, and the monofilaments have a core-sheath structure, which is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6.

[0294] The core layer contains core-shell structured silicone polyester aerogel particles, and the mass of the core-shell structured silicone polyester aerogel particles in the core layer is 30% of the mass of the polyester.

[0295] The core-sheath type polyester aerogel fiber has the following specifications: 150D / 96F, density: 0.15g / cm³, breaking strength: 2.45cN / dtex, breaking elongation: 25%, and thermal conductivity: 0.032W / (m·K).

[0296] Example B7

[0297] A method for preparing core-sheath type polyester aerogel fiber, comprising the following steps:

[0298] (1) Preparation of raw materials;

[0299] Silicon-containing polyester aerogel particles with core-shell structure: the silicon-containing polyester aerogel particles with core-shell structure prepared in Example A7 were dried at 80℃ for 2h;

[0300] Polyester: PET, intrinsic viscosity of 0.66dL / g, water content ≤0.4%;

[0301] Silane coupling agent: vinyl silane coupling agent A-151;

[0302] NMMO;

[0303] Antioxidant: manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., brand is Antioxidant AN 215 (B215);

[0304] (2) The dried silicon-containing polyester aerogel particles with core-shell structure, polyester, silane coupling agent, NMMO, antioxidant were added into a high-speed mixer, and stirred at 88℃ at a speed of 450r / min for 35min to obtain a premix; wherein the mass of silane coupling agent, NMMO and antioxidant was 5wt%, 3wt% and 1wt% of the mass of silicon-containing polyester aerogel particles with core-shell structure, respectively;

[0305] (3) The premix was added into a twin-screw extruder together with polyester, and after melt blending, extruded and pelletized; wherein the screw speed was 130r / min, the initial melting zone temperature of the twin-screw extruder was 263℃, the melting zone temperature was 276℃, the extruder temperature was 282℃, the water tank temperature was 30℃, and the pelletizer speed was 289r / min;

[0306] (4) The pellets were soaked in n-hexane at 25℃ for 1.5h;

[0307] (5) The soaked pellets were first dried at 80℃ for 1.4h, then dried at 100℃ for 1.4h, and finally dried at 124℃ for 2h;

[0308] (6) The dried pellets were vacuum dried at 105℃ for 6h, and the water content was controlled to be ≤0.05wt%, thereby obtaining the core layer raw material; wherein the vacuum degree during vacuum drying was -0.05;

[0309] (7) The core layer raw material in step (6) was used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) was used as the skin layer raw material, and then a skin-core composite process was used for spinning, and the process flow was: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a form;

[0310] The process parameters of the core-sheath composite spinning include: spinning temperature 273℃, spinning speed 920m / min, slow cooling zone temperature 88℃, first stretching temperature 58℃, first stretching multiple 1.5, second stretching temperature 130℃, second stretching multiple 3, third stretching temperature 100℃, third stretching multiple 1.05, setting temperature 92℃, setting time 15min.

[0311] The cross section of the single fiber of the finally prepared core-sheath polyester aerogel fiber is circular, and the single fiber has a core-sheath structure, and the core-sheath structure is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6;

[0312] The core layer disperses the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 45% of the mass of the polyester;

[0313] The specification of the core-sheath polyester aerogel fiber is 150D / 72F, the density is 0.18g / cm³, the breaking strength is 2.56cN / dtex, the breaking elongation is 15%, and the thermal conductivity is 0.03W / (m·K).

[0314] Example B8

[0315] A preparation method of a core-sheath polyester aerogel fiber, the steps are as follows:

[0316] (1) Preparation of raw materials;

[0317] Core-shell structure silicon-containing polyester aerogel particles: the core-shell structure silicon-containing polyester aerogel particles prepared in Example A8 are dried at 80℃ for 2h;

[0318] Polyester: PET, intrinsic viscosity 0.66dL / g, water content ≤0.4%;

[0319] Silane coupling agent: 3-carboxypropyltrimethoxysilane and vinyl silane coupling agent A-172 in a mass ratio of 1:1;

[0320] NMMO;

[0321] Antioxidant: manufacturer Qingdao Jidejia New Material Technology Co., Ltd., brand antioxidant AN 215(B215);

[0322] (2) The dried core-shell structure silicon-containing polyester aerogel particles, polyester, silane coupling agent, NMMO, antioxidant are added into a high-speed mixer, stirred at 85℃ and a speed of 420r / min for 48min to obtain a premix; wherein the mass of the silane coupling agent, NMMO and antioxidant is 5wt%, 3wt% and 1wt% of the mass of the core-shell structure silicon-containing polyester aerogel particles, respectively;

[0323] (3) The premixed material and polyester are added together to a twin-screw extruder, and after melt blending, they are extruded and pelletized; wherein, the screw speed is 150 r / min, the initial melting zone temperature of the twin-screw extruder is 260℃, the melting zone temperature is 279℃, the extruder temperature is 281℃, the water tank temperature is 29℃, and the pelletizer speed is 283 r / min;

[0324] (4) Soak the slices in hexane at 26°C for 1.6 h;

[0325] (5) After soaking, the slices are dried at 79℃ for 2 hours, then at 96℃ for 1.2 hours, and then at 122℃ for 1.7 hours.

[0326] (6) The dried slices were vacuum dried at 108℃ for 5 hours, and the moisture content was controlled to be ≤0.05wt% to obtain the core material; wherein the vacuum degree during vacuum drying was -0.07;

[0327] (7) Use the core material in step (6) as the core material and polyester (the same polyester used when preparing the core material) as the sheath material. Then use the sheath-core composite process for spinning. The process flow is: melting → metering → extrusion → monomer suction → side blowing cooling → bundling and oiling → first stretching → second stretching → third stretching → shaping → winding.

[0328] The process parameters for core-sheath composite spinning include: spinning temperature 292℃, spinning speed 980m / min, slow cooling zone temperature 90℃, first stretching temperature 60℃, first stretching ratio 1.8, second stretching temperature 128℃, second stretching ratio 2.5, third stretching temperature 108℃, third stretching ratio 1.1, setting temperature 96℃, and setting time 12min.

[0329] The final core-sheath type polyester aerogel fiber has a circular cross-section for the monofilaments, and the monofilaments have a core-sheath structure, which is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6.

[0330] The core layer contains core-shell structured silicon-containing polyester aerogel particles, and the mass of the core-shell structured silicon-containing polyester aerogel particles in the core layer is 40% of the mass of the polyester.

[0331] The core-sheath type polyester aerogel fiber has the following specifications: 150D / 72F, density: 0.16g / cm³, breaking strength: 2.31cN / dtex, breaking elongation: 20%, and thermal conductivity: 0.031W / (m·K).

[0332] Example B9

[0333] A method for preparing core-sheath type polyester aerogel fiber, comprising the following steps:

[0334] (1) Preparation of raw materials;

[0335] Silicon-containing polyester aerogel particles with core-shell structure: the silicon-containing polyester aerogel particles with core-shell structure prepared in Example A9 were dried at 80℃ for 2h;

[0336] Polyester: PET, intrinsic viscosity of 0.66dL / g, water content ≤0.4%;

[0337] Silane coupling agent: methacryloxy silane coupling agent KH570;

[0338] NMMO;

[0339] Antioxidant: the manufacturer is Qingdao Jidejia New Material Technology Co., Ltd., and the brand is Antioxidant AN 215 (B215);

[0340] (2) The dried silicon-containing polyester aerogel particles with core-shell structure, polyester, silane coupling agent, NMMO, antioxidant were added into a high-speed mixer and stirred at 83℃ at a speed of 480r / min for 38min to obtain a premix; wherein the mass of silane coupling agent, NMMO and antioxidant was 5wt%, 3wt% and 1wt% of the mass of silicon-containing polyester aerogel particles with core-shell structure, respectively;

[0341] (3) The premix was added into a twin-screw extruder together with polyester, and after melt blending, it was extruded and pelletized; wherein the screw speed was 140r / min, the initial melting zone temperature of the twin-screw extruder was 266℃, the melting zone temperature was 273℃, the extruder temperature was 285℃, the water tank temperature was 31℃, and the pelletizer speed was 282r / min;

[0342] (4) The pellets were soaked in n-hexane at 30℃ for 2.2h;

[0343] (5) The soaked pellets were first dried at 83℃ for 1.8h, then dried at 98℃ for 1.8h, and finally dried at 125℃ for 1.6h;

[0344] (6) The dried pellets were vacuum dried at 104℃ for 5.5h, and the water content was controlled to be ≤0.05wt%, thereby obtaining the core layer raw material; wherein the vacuum degree during vacuum drying was -0.06;

[0345] (7) The core layer raw material in step (6) was used as the core layer raw material, and the polyester (the same as the polyester used in the preparation of the core layer raw material) was used as the skin layer raw material, and then a skin-core composite process was used for spinning, and the process flow was: melting → metering → extrusion → monomer suction → side air cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a form;

[0346] The process parameters of the core-sheath composite spinning include: spinning temperature 285℃, spinning speed 1000m / min, slow cooling zone temperature 92℃, first stretching temperature 58℃, first stretching multiple 2.2, second stretching temperature 126℃, second stretching multiple 2.5, third stretching temperature 105℃, third stretching multiple 0.9, setting temperature 102℃, setting time 9min.

[0347] The cross section of the single fiber of the finally prepared core-sheath polyester aerogel fiber is circular, and the single fiber has a core-sheath structure, and the core-sheath structure is a positive core-sheath structure; the mass ratio of the sheath layer to the core layer is 4:6;

[0348] The core layer disperses the core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 25% of the mass of the polyester;

[0349] The specification of the core-sheath polyester aerogel fiber is 150D / 96F, the density is 0.14g / cm³, the breaking strength is 2.35cN / dtex, the breaking elongation is 28%, and the thermal conductivity is 0.035W / (m·K).

[0350] Comparative Example 2

[0351] A method for preparing a core-sheath polyester aerogel fiber, which is basically the same as Example B9, except that the amount of core-shell structure silicon-containing polyester aerogel particles is reduced in step (2) (the mass of silane coupling agent, NMMO, and antioxidant also changes accordingly).

[0352] The mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer of the finally prepared core-sheath polyester aerogel fiber is 20% of the mass of the polyester;

[0353] The breaking strength of the core-sheath polyester aerogel fiber is 3.1cN / dtex, the breaking elongation is 30%, and the thermal conductivity is 0.038W / (m·K).

[0354] Comparing Comparative Example 2 and Example B9, it can be seen that the breaking strength and breaking elongation of the core-sheath polyester aerogel fiber prepared in Comparative Example 2 increase, and the thermal conductivity increases. This is because the mechanical properties of polyester are good, which can improve the mechanical properties of the core-sheath polyester aerogel fiber, but the thermal conductivity of the core-sheath polyester aerogel fiber will be affected by the mass ratio of the core-shell structure silicon-containing polyester aerogel particles in the core layer. In Comparative Example 2, the mass ratio of the core-shell structure silicon-containing polyester aerogel particles in the core layer is small, which will lead to an increase in the thermal conductivity of the prepared core-sheath polyester aerogel fiber and a decrease in the thermal insulation performance.

[0355] Comparative Example 3

[0356] A kind of preparation method of skin-core type polyester aerogel fiber, substantially same as embodiment B9, the only difference is that the core-shell structure of the silicon-containing polyester aerogel particles in step (1) is replaced by equal mass of silica aerogel (average particle size is 3 μm, porosity is 93%).

[0357] The structure of the finally prepared skin-core type polyester aerogel fiber is substantially the same as that of embodiment B9, except that the breaking strength of the skin-core type polyester aerogel fiber is 2.18 cN / dtex, the elongation at break is 25%, and the thermal conductivity is 0.042 W / (m·K).

[0358] Comparing comparative example 3 with embodiment B9, it can be seen that the breaking strength and elongation at break of the skin-core type polyester aerogel fiber prepared in comparative example 3 are reduced, and the thermal conductivity is increased. This is because the interfacial bonding force between conventional silica aerogel and polyester is weak, which leads to brittle fracture of the fiber, resulting in a decrease in breaking strength and elongation at break. The core-shell structure of the silicon-containing polyester aerogel particles used in embodiment B9 improves the interfacial bonding force between organic and inorganic, and the core-shell structure of the silicon-containing polyester aerogel particles is coated inside the polyester, which reduces the plugging of the aerogel voids by polyester and the damage to the structure of the aerogel particles caused by mechanical stirring during the blending process, so that the prepared skin-core type polyester aerogel fiber has good mechanical properties and thermal insulation effect.

Claims

1. A core-sheath polyester aerogel fiber, characterized by, The monofilament has a sheath-core structure; The base material of the sheath layer is polyester; The base material of the core layer is polyester, and the core layer is dispersed with core-shell structure silicon-containing polyester aerogel particles, and the mass of the core-shell structure silicon-containing polyester aerogel particles in the core layer is 25%-45% of the mass of the polyester; The preparation steps of the core-shell structure silicon-containing polyester aerogel particles are as follows: (a) soaking the hydrophilic silica aerogel in an ethanol solution to activate the surface hydroxyl group and obtain modified hydrophilic silica aerogel; (b) mixing the modified hydrophilic silica aerogel, silane coupling agent, PTA, ethylene glycol, water and other substances, and then heating to hydrolyze the silane coupling agent, and the hydrolyzed silane coupling agent reacts with the modified hydrophilic silica aerogel at one end to form a covalent bond, and reacts with PTA and / or one end of ethylene glycol at the other end to form a covalent bond, wherein the other substances include an initiator and a catalyst; (c) adjusting the reaction conditions to make PTA and ethylene glycol undergo esterification and polycondensation reactions in sequence.

2. The core-sheath polyester aerogel fiber according to claim 1, wherein, The cross section of the monofilament is circular, and the sheath-core structure is a positive sheath-core structure; the mass ratio of the sheath layer to the core layer is 4:6; the base material of the sheath layer is PET or low-melting-point PET, the melting point of the low-melting-point PET is 110-130℃, and the base material of the core layer is PET; and the sheath layer is dispersed with 0-20wt% functional powder.

3. The core-sheath polyester aerogel fiber according to claim 1, wherein, The average particle size of the hydrophilic silica aerogel is 1-3µm, the porosity is greater than 90%, and the bulk density is not more than 28.5g / L; The silane coupling agent is one or more of epoxy silane coupling agent, amino silane coupling agent, methacryloxy silane coupling agent, vinyl silane coupling agent and 3-carboxypropyl trimethoxysilane.

4. The core-sheath polyester aerogel fiber according to claim 1, wherein, In step (a), the water content of the ethanol solution is 3-15wt%, the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:10-20, the soaking temperature is 25-30℃, and the soaking time is 2-3h; In step (b), in the mixed system, the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol is 1:6-10, the molar ratio of ethylene glycol to PTA is 1-3:1, the mass of the silane coupling agent is 1-15% of the mass of the modified hydrophilic silica aerogel, the mass of the initiator is 0.1-1% of the total mass of PTA and ethylene glycol, and the mass of the catalyst is 0.01-0.05% of the total mass of PTA and ethylene glycol; the pH value of the system is adjusted to 4-5 during heating, the heating temperature is 60-100℃, and the heating time is 5-6h; In step (b), the other substances also include an amphiphilic solvent; in the mixed system, the mass of the amphiphilic solvent is 3-20% of the total mass of PTA and ethylene glycol; In step (b), the process of mixing the modified hydrophilic silica aerogel, silane coupling agent, PTA, ethylene glycol, water and other substances is as follows: under ultrasonic assistance, the modified hydrophilic silica aerogel is dispersed in the mixed solution of PTA, ethylene glycol and water, and then the silane coupling agent and other substances are added, wherein the ultrasonic frequency is 30-50kHz; In step (c), the reaction conditions of the esterification reaction are: temperature 240-260 DEG C, pressure 0.1 MPa, time 2-3 h; the conditions of the polycondensation reaction are: temperature 270-290 DEG C, pressure below 100 Pa, time 3-4 h.

5. The core-sheath polyester aerogel fiber according to claim 1, wherein, The preparation steps of the core-shell structure silicon-containing polyester aerogel particle further comprise step (d): after the reaction system of step (c) is cooled to 120-150 DEG C, a bifunctional crosslinking agent is added thereto and kept for 1-2 h; the mass addition amount of the bifunctional crosslinking agent in step (d) is 0.5-2% of the total mass of PTA and ethylene glycol in step (b).

6. The core-sheath polyester aerogel fiber according to claim 5, wherein, The preparation steps of the core-shell structure silicon-containing polyester aerogel particle further comprise step (e): after the solid product of step (d) is replaced in a replacement agent, it is taken out, and sequentially dried at 25 DEG C for 1-2 h, at 50 DEG C for 2-3 h, and at 80 DEG C for 2-3 h.

7. The core-sheath polyester aerogel fiber according to any one of claims 1 to 6, characterized in that, The skin-core type polyester aerogel fiber has a specification of 75-150D / 48-96F, a density of 0.14-0.18 g / cm3, an intrinsic viscosity of 0.65±0.05 dL / g, a breaking strength of ≥2.22 cN / dtex, an elongation at break of 15-35%, a thermal conductivity of 0.028-0.035 W / (m·K), and a pore retention rate of the core-shell structure silicon-containing polyester aerogel particle of >85%.

8. A process for preparing a core-sheath polyester aerogel fiber as claimed in any one of claims 1 to 7, characterized in that, After the core layer raw material and the skin layer raw material are prepared respectively, the skin-core composite spinning is performed, and the skin-core type polyester aerogel fiber is obtained.

9. The method of claim 8, wherein, The preparation steps of the core layer raw material are as follows: (i) the dried core-shell structure silicon-containing polyester aerogel particle, polyester, silane coupling agent, NMMO and antioxidant are added into a high-speed mixer, stirred at a speed of 300-500 r / min at 80-100 DEG C for 30-60 min to obtain a premix, wherein the mass of the silane coupling agent, NMMO and antioxidant is 5 wt%, 3 wt% and 1 wt% of the mass of the core-shell structure silicon-containing polyester aerogel particle respectively; (ii) the premix and the polyester are added into a twin-screw extruder, extruded and pelletized after melt blending; the temperature of each zone of the twin-screw extruder is: zone 1 260-270 DEG C, zone 2 270-280 DEG C, zone 3 280-290 DEG C, and the temperature of the extruder is 280-285 DEG C; the screw rotation speed is 100-200 r / min; (iii) the pellets are soaked in n-hexane for 1.5-2.5 h; (iv) the pellets are gradient dried, that is, first dried at 75-85 DEG C for 1-2 h, then dried at 95-105 DEG C for 1-2 h, and finally dried at 115-125 DEG C for 1-2 h; (v) the pellets are vacuum dried at 90-110 DEG C for 4-6 h, and the water content is controlled to be ≤0.05 wt%, thereby obtaining the core layer raw material.

10. The method of claim 8, wherein, The process flow of the skin-core composite spinning is: melting → metering → extrusion → monomer suction → side air blowing cooling → bunching and oiling → first stretching → second stretching → third stretching → setting → winding into a shape. The process parameters of the core-sheath composite spinning include: spinning temperature 260-300 DEG C, spinning speed 800-1200 m / min, slow cooling zone temperature 80-100 DEG C, first stretching temperature 55-70 DEG C, first stretching multiple 1.8-2.2, second stretching temperature 120-135 DEG C, second stretching multiple 2.5-3.0, third stretching temperature 95-110 DEG C, third stretching multiple 0.9-1.05, setting temperature 90-105 DEG C, setting time 8-15 min.

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