Silicon-containing polyester aerogel particle with core-shell structure and preparation method of silicon-containing polyester aerogel particle

Abstract

The invention belongs to the technical field of aerogel composite materials, and discloses a silicon-containing polyester aerogel particle with a core-shell structure and a preparation method of the silicon-containing polyester aerogel particle, the preparation method comprises the following steps: (a) soaking hydrophilic silicon dioxide aerogel in an ethanol solution, and activating surface hydroxyl to obtain modified hydrophilic silicon dioxide aerogel; (b) mixing the modified hydrophilic silicon dioxide aerogel, a silane coupling agent, PTA, ethylene glycol, water and other substances, heating to hydrolyze the silane coupling agent, reacting one end of the hydrolyzed silane coupling agent with the modified hydrophilic silicon dioxide aerogel to form a covalent bond, and reacting the other end of the hydrolyzed silane coupling agent with one end of PTA and / or ethylene glycol to form a covalent bond; and (c) adjusting reaction conditions to enable PTA and ethylene glycol to be subjected to esterification reaction and condensation polymerization in sequence. The problems of low strong interface bonding force, non-uniform dispersion and the like in the current bonding process of the silicon dioxide aerogel and the polyester are successfully solved.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of aerogel composites, and particularly relates to a core-shell structure silicon-containing polyester aerogel particle and a preparation method thereof. BACKGROUND

[0002] With the continuous development of material science, silica aerogel has attracted widespread attention in many fields due to its low density, high porosity and other excellent properties, and has become a popular research object for the preparation of high-performance composites. However, there are many technical problems to be solved in the process of compounding silica aerogel and polyester.

[0003] In the prior art, a patent application with the application publication number CN117430922A discloses a method for preparing a silicon-containing aerogel polyester master batch for the production of a silicon-containing aerogel polyester fiber by blending silica aerogel and polyethylene terephthalate with a dispersing agent and mechanical stirring. Although this method can give the fiber good heat insulation performance, the interfacial bonding force between the silica aerogel and the polyester is weak (shear strength ≤ 5 MPa), which leads to brittle fracture of the composite fiber material during use.

[0004] To solve this problem, the prior art proposes a two-step method of "modification before compounding". In the first step, silica aerogel is modified by using a silane coupling agent (such as KH550, KH560). The typical steps are as follows: the silane coupling agent undergoes a hydrolysis reaction under specific conditions, and the alkoxyl groups (-OR) in the molecule are attacked by water molecules and gradually converted into silanol groups (-Si-OH); then, the generated silanol groups react with the hydroxyl groups (-OH) on the surface of the silica aerogel through condensation reaction, and Si-O-Si bonds are formed by dehydration, thereby grafting the silane coupling agent onto the surface of the silica aerogel and achieving the modification of the silica aerogel. In the second step, the modified silica aerogel is compounded with polyester to form a polyester shell layer on the surface of the modified silica aerogel. However, this method does not form chemical bonding between the silica aerogel and the polyester shell layer, and the interfacial bonding force between the silica aerogel and the polyester shell layer is still weak (shear strength is about 8.5 MPa), and the polyester shell layer is easy to fall off, which makes it difficult to ensure the long-term stable use effect of the composite material.

[0005] Therefore, it is necessary to propose a method that can form chemical bonding between silica aerogel and polyester, and based on which a core-shell structure silicon-containing polyester aerogel particle is prepared. SUMMARY

[0006] The present application aims at solving the problems in the prior art and providing a core-shell structure silicon-containing polyester aerogel particle and a preparation method thereof.

[0007] To achieve the above-mentioned purpose, the technical scheme adopted by the present application is as follows:

[0008] A preparation method of a core-shell structure silicon-containing polyester aerogel particle, comprising the following steps:

[0009] (a) soaking the hydrophilic silica aerogel in an ethanol solution to activate the surface hydroxyl group, thereby obtaining modified hydrophilic silica aerogel;

[0010] (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, 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 the other substances include an initiator (such as ammonium persulfate) and a catalyst;

[0011] Taking the silane coupling agent KH560 as an example, the reaction process of step (b) is described, and the reaction equation is as follows:

[0012] ① Hydrolysis of the silane coupling agent, and the reaction equation is as follows:

[0013] (CH3O)3Si-(CH2)3-O-CH2-CH(O)CH2+3H2O→(HO)3Si-(CH2)3-O-CH2-CH(O)CH2+3CH3OH;

[0014] ② Reaction of one end of the hydrolyzed silane coupling agent with the modified hydrophilic silica aerogel, and the reaction equation is as follows:

[0015] n(HO)3Si-(CH2)3-O-CH2-CH(O)CH2+(HO)n-SiO2→SiO2-[Si-(CH2)3-O-CH2-CH(O)CH2] n +nH2O;

[0016] ③ Reaction of the other end of the hydrolyzed silane coupling agent with one end of the PTA and / or ethylene glycol, and part of the reaction equation is as follows:

[0017] 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;

[0018] (c) adjusting the reaction conditions so that PTA and ethylene glycol undergo esterification and polycondensation in sequence;

[0019] 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:

[0020] 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;

[0021] After the polyester segment is connected to the modified hydrophilic silica aerogel through the silane coupling agent, the polyester segments form a physical entanglement network through self-entanglement, and finally form a uniform polyester shell on the surface of the silica aerogel.

[0022] As a preferred technical solution:

[0023] The preparation method of the core-shell structure silicon-containing polyester aerogel particle 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.

[0024] The preparation method of the core-shell structure silicon-containing polyester aerogel particle as described above, wherein 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 (A-151, A-172), and 3-carboxypropyltrimethoxysilane.

[0025] The preparation method of the core-shell structure silicon-containing polyester aerogel particle 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 soaking temperature is 25-30℃, and the soaking time is 2-3 h.

[0026] The preparation method of the core-shell structure silicon-containing polyester aerogel particles as described above, in step (b), the mass ratio of the modified hydrophilic silica aerogel to the total mass of PTA and ethylene glycol in the mixed system 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 5-6h.

[0027] The preparation method of the core-shell structure silicon-containing polyester aerogel particles as described above, in step (b), the other substances further 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.

[0028] The preparation method of the core-shell structure silicon-containing polyester aerogel particles as described above, 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 30-50kHz; in the early stage of polymerization, the silica aerogel is forcibly dispersed by high-frequency ultrasound, which can effectively avoid the agglomeration phenomenon.

[0029] The preparation method of the core-shell structure silicon-containing polyester aerogel particles as described above, in step (c), the reaction conditions of the esterification reaction are as follows: the temperature is 240-260℃, the pressure is 0.1MPa, and the time is 2-3h; the conditions of the polycondensation reaction are as follows: the temperature is 270-290℃, the pressure is below 100Pa, and the time is 3-4h.

[0030] The preparation method of the core-shell structure silicon-containing polyester aerogel particle as described above further comprises the following step (d): after the reaction system of step (c) is cooled to 120-150 DEG C, a bifunctional crosslinking agent (such as divinylbenzene) is added and kept for 1-2 hours; the mass of the bifunctional crosslinking agent added in step (c) is 0.5-2% of the total mass of PTA and ethylene glycol in step (b). The purpose of step (d) is to initiate the covalent crosslinking of the bifunctional crosslinking agent and the polyester, to build a stable three-dimensional chemical network in the polyester shell layer, to form a double network with the physical entanglement network formed between the polyester segments by self-entanglement, to enhance the structural stability of the polyester shell layer, to avoid the collapse or deformation of the pores due to water absorption or external pressure in the subsequent use process, and to greatly enhance the practicability and durability of the material.

[0031] The preparation method of the core-shell structure silicon-containing polyester aerogel particle as described above further comprises the following step (e): after the solid product of step (d) is replaced in a displacement agent (such as ethanol, n-hexane), it is taken out, dried at 25 DEG C for 1-2 hours, dried at 50 DEG C for 2-3 hours, and dried at 80 DEG C for 2-3 hours; the present application uses solvent replacement combined with gradient temperature drying to replace the traditional supercritical drying process, greatly reducing the equipment demand and energy consumption.

[0032] The present application also provides a core-shell structure silicon-containing polyester aerogel particle, which is prepared by the preparation method of the core-shell structure silicon-containing polyester aerogel particle as described above. The shear strength (which is an index reflecting the interfacial bonding force) of the bifunctional core-shell structure silicon-containing polyester aerogel particle prepared without using a bifunctional crosslinking agent is not less than 9.4 MPa, the average coating rate of the modified hydrophilic silica aerogel by the polyester shell layer is not less than 68%, and the thermal conductivity is not higher than 0.025 W / (m·K).

[0033] The shear strength of the bifunctional core-shell structure silicon-containing polyester aerogel particle prepared by using a bifunctional crosslinking agent is not less than 12.5 MPa, the average coating rate of the modified hydrophilic silica aerogel by the polyester shell layer is not less than 90%, and the thermal conductivity is not higher than 0.025 W / (m·K).

[0034] Advantages:

[0035] (1) The present application realizes the chemical bond between the silica aerogel and the polyester through the silane coupling agent; at the same time, a double network is built in the polyester shell layer to firmly anchor the silica aerogel core, and finally the interfacial performance is comprehensively improved. Compared with the traditional physical mixing method, the interfacial bonding force is improved by more than 50%.

[0036] (2) By introducing ultrasonic-assisted dispersion technology and combining it with amphiphilic solvents, the present invention achieves uniform dispersion of silica aerogel in the system, so that the average coating rate of the polyester shell on the modified hydrophilic silica aerogel is not less than 90%.

[0037] (3) This invention successfully solves the problems of low interfacial bonding force and uneven dispersion that occur in the current process of combining silica aerogel with polyester. The resulting core-shell structured silica-containing polyester aerogel particles have the advantages of high thermal insulation, mechanical strength and low cost, and have broad application prospects in the fields of thermal insulation textiles, construction and new energy. Attached Figure Description

[0038] Figure 1 This is a transmission electron microscope image of the core-shell structured silicon-containing polyester aerogel particles obtained in Example 1 of the present invention. Detailed Implementation

[0039] The present invention will be further described below with reference to specific embodiments. It should be understood that these embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. Furthermore, it should be understood that after reading the teachings of this invention, those skilled in the art can make various alterations or modifications to the invention, and these equivalent forms also fall within the scope defined by the appended claims.

[0040] To ensure that the performance of the substances used in each embodiment is fully disclosed, the manufacturers and brands of the substances are specified. Other products from other manufacturers and brands that conform to the limitations of this invention are also feasible.

[0041] The testing methods for the relevant performance indicators in the following embodiments are as follows:

[0042] Shear strength: The core-shell structured silicon-containing polyester aerogel particles prepared in each embodiment were used as samples, and the shear strength of the samples was determined in accordance with GB / T 28889-2012 "Test Method for In-Plane Shear Properties of Composite Materials".

[0043] Thermal conductivity: The core-shell structured silicon-containing polyester aerogel particles prepared in each embodiment were used as samples, and the thermal conductivity of the samples was determined in accordance with GB / T 10294-2008 "Determination of steady-state thermal resistance and related properties of thermal insulation materials - protective hot plate method".

[0044] Coating efficiency: The core-shell structured silicon-containing polyester aerogel particles prepared in each embodiment were used as samples, and then tested using a particle size analyzer. The coating efficiency η (in %) was calculated based on the measured data. The formula for calculating the coating efficiency is: η = ×100%, where D is the diameter of the sample (µm) and d is the particle size of the hydrophilic silica aerogel particles (µm).

[0045] Example 1

[0046] A method for preparing a core-shell structure of a silicon-containing polyester aerogel particle, the steps are as follows:

[0047] (1) Preparation of raw materials;

[0048] Hydrophilic silica aerogel: average particle size of 1 µm, porosity of 93%, bulk density of 22 g / L;

[0049] Ethanol solution: water content of 5 wt%;

[0050] Ethylene glycol;

[0051] PTA (pure terephthalic acid);

[0052] Water;

[0053] Silane coupling agent: vinyl silane coupling agent A-151;

[0054] Initiator: ammonium persulfate;

[0055] Catalyst: antimony ethylene glycol;

[0056] Amphiphilic solvent: N-methylmorpholine-N-oxide;

[0057] Acetic acid;

[0058] Bifunctional crosslinking agent: divinylbenzene;

[0059] Displacement agent: n-hexane;

[0060] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, first ultrasonic dispersed at a frequency of 40 kHz for 0.5 h and refluxed for 2.5 h, then vacuum dried to activate the surface hydroxyl group to obtain a 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°C, the soaking time is 2.6 h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2 h;

[0061] (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 a temperature of 90°C 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 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 1:6, 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;

[0062] (4) The reaction system of step (3) is first esterified at a temperature of 240°C and a pressure of 0.1 MPa for 3 h, and then subjected to polycondensation reaction at a temperature of 270°C and a pressure of 95 Pa for 3.5 h;

[0063] (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 1% of the total mass of PTA and ethylene glycol of step (3);

[0064] (6) After the solid product of step (5) is subjected to replacement in a displacement agent, it is taken out, dried at 25°C for 2 h, dried at 50°C for 3 h, and dried at 80°C for 3 h in sequence, to obtain a core-shell structure silicon-containing polyester aerogel particle.

[0065] The final core-shell structure silicon-containing polyester aerogel particle (the electron microscope image of which is shown in Figure 1 ) has a shear strength of 12.5 MPa, an average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel of 92%, and a thermal conductivity of 0.022 W / (m·K).

[0066] Example 2

[0067] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, comprising the following steps:

[0068] (1) Preparation of raw materials;

[0069] The hydrophilic silica aerogel has an average particle size of 3 µm, a porosity of 93%, and a bulk density of 22 g / L;

[0070] Ethanol solution: water content of 5wt%;

[0071] Ethylene glycol;

[0072] PTA (pure terephthalic acid);

[0073] Water;

[0074] Silane coupling agent: 3-carboxypropyltrimethoxysilane;

[0075] Initiator: ammonium persulfate;

[0076] Catalyst: ethylene glycol antimony;

[0077] Amphiphilic solvent: N-methylmorpholine-N-oxide;

[0078] Acetic acid;

[0079] Bifunctional crosslinking agent: divinylbenzene;

[0080] Displacement agent: n-hexane;

[0081] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, ultrasonically dispersed at a frequency of 40 kHz for 0.8 h, and vacuum dried after refluxing for 2.6 h 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 2.2 h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2 h;

[0082] (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 heating at a temperature of 90°C for 5 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 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 1:10, 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;

[0083] (4) the reaction system of step (3) is first esterified under the condition of a temperature of 250°C and a pressure of 0.1 MPa for 2 h, and then subjected to polycondensation under the condition of a temperature of 280°C and a pressure of 90 Pa for 4 h;

[0084] (5) after the reaction system of step (4) is cooled to 150°C, a bifunctional crosslinking agent is added thereto and kept for 1.5 h; wherein the mass addition amount of the bifunctional crosslinking agent is 0.8% of the total mass of PTA and ethylene glycol of step (3);

[0085] (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, and then the core-shell structure silicon-containing polyester aerogel particles are prepared.

[0086] The shear strength of the finally prepared core-shell structure silicon-containing polyester aerogel particles is 12.6 MPa, the average coating rate of the modified hydrophilic silica aerogel by the polyester shell layer is 93%, and the thermal conductivity is 0.021 W / (m·K).

[0087] Example 3

[0088] A method for preparing core-shell structure silicon-containing polyester aerogel particles, the steps are as follows:

[0089] (1) preparation of raw materials;

[0090] hydrophilic silica aerogel: average particle size of 2 µm, porosity of 91%, bulk density of 26 g / L;

[0091] ethanol solution: water content of 3 wt%;

[0092] ethylene glycol;

[0093] PTA (terephthalic acid);

[0094] water;

[0095] silane coupling agent: epoxy silane coupling agent KH560;

[0096] initiator: ammonium persulfate;

[0097] catalyst: antimony ethylene glycol;

[0098] amphiphilic solvent: N-methylmorpholine-N-oxide;

[0099] acetic acid;

[0100] bifunctional crosslinking agent: divinylbenzene;

[0101] displacement agent: n-hexane;

[0102] (2) the hydrophilic silica aerogel is soaked in an ethanol solution, is dispersed for 1 h under ultrasonic assistance at a frequency of 40 kHz, and is vacuum dried after reflux reaction for 2 h to activate the surface hydroxyl groups, so as 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℃, the soaking time is 2 h, the vacuum drying temperature is 60℃, and the vacuum drying time is 2 h;

[0103] (3) the modified hydrophilic silica aerogel is dispersed in a mixed solution of PTA, ethylene glycol and water under ultrasonic assistance at a frequency of 30 kHz, and then the silane coupling agent, the initiator, the catalyst and the amphiphilic solvent are added and dispersed for 20 min, and the hydrolysis of the silane coupling agent is performed under the protection of nitrogen at a temperature of 60℃ 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 the PTA and / or the 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 the PTA and the ethylene glycol is 1:9, the molar ratio of the ethylene glycol to the 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 the PTA and the ethylene glycol, the mass of the catalyst is 0.04% of the total mass of the PTA and the ethylene glycol, and the mass of the amphiphilic solvent is 10% of the total mass of the PTA and the ethylene glycol, and the pH value of the system is adjusted to 4 during the heating process;

[0104] (4) the reaction system of step (3) is first subjected to esterification reaction at a temperature of 260℃ and a pressure of 0.1 MPa for 2 h, and then subjected to polycondensation reaction at a temperature of 290℃ and a pressure of 85 Pa for 3 h;

[0105] (5) after the reaction system of step (4) is cooled to 120℃, a bifunctional crosslinking agent is added thereto and incubated for 1 h; wherein the mass of the bifunctional crosslinking agent added is 0.5% of the total mass of the PTA and the ethylene glycol of step (3);

[0106] (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 h, dried at 50℃ for 2 h, and dried at 80℃ for 2 h in sequence, so as to obtain the core-shell structure silicon-containing polyester aerogel particles.

[0107] The shear strength of the finally obtained core-shell structure silicon-containing polyester aerogel particles is 12.5 MPa, the average coating rate of the polyester shell layer to the modified hydrophilic silica aerogel is 91.5%, and the thermal conductivity is 0.023 W / (m·K).

[0108] Example 4

[0109] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, comprising the following steps:

[0110] (1) Preparation of raw materials;

[0111] Hydrophilic silica aerogel: average particle size of 3 µm, porosity of 92%, bulk density of 26 g / L;

[0112] Ethanol solution: water content of 15 wt%;

[0113] Ethylene glycol;

[0114] PTA (pure terephthalic acid);

[0115] Water;

[0116] Silane coupling agent: amino silane coupling agent KH550;

[0117] Initiator: ammonium persulfate;

[0118] Catalyst: ethylene glycol antimony;

[0119] Amphiphilic solvent: N-methyl morpholine-N-oxide;

[0120] Acetic acid;

[0121] Bifunctional crosslinking agent: divinyl benzene;

[0122] Displacement agent: ethanol;

[0123] (2) Soaking the hydrophilic silica aerogel in the ethanol solution, first ultrasonic dispersion at a frequency of 40 kHz for 0.6 h and reflux reaction for 2.5 h, then vacuum drying to activate the surface hydroxyl group 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°C, the soaking time is 2.5 h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2 h;

[0124] (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, then a silane coupling agent, an initiator, a catalyst and an amphiphilic solvent are added and ultrasonically dispersed for 25 min, and the mixture is heated at 100 DEG C for 6 h under the protection of nitrogen 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 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 1:7, 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;

[0125] (4) the reaction system of step (3) is first esterified at a temperature of 255 DEG C and a pressure of 0.1 MPa for 2 h, and then polycondensed at a temperature of 275 DEG C and a pressure of 95 Pa for 4 h;

[0126] (5) after the reaction system of step (4) is cooled to 130 DEG C, 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);

[0127] (6) after the solid product of step (5) is replaced in a displacement agent, it is taken out, dried at 25 DEG C for 1.5 h, at 50 DEG C for 2.5 h, and at 80 DEG C for 2.5 h, respectively, to obtain a core-shell structure of silicon-containing polyester aerogel particles.

[0128] The shear strength of the finally prepared core-shell structure of 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).

[0129] Example 5

[0130] A method for preparing a core-shell structure of silicon-containing polyester aerogel particles, which is basically the same as example 4, except that no bifunctional crosslinking agent is added in step (5).

[0131] The shear strength of the finally prepared core-shell structure of 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).

[0132] Example 6

[0133] A method for preparing a core-shell structure of a silicon-containing polyester aerogel particle, the steps are as follows:

[0134] (1) Preparation of raw materials;

[0135] Hydrophilic silica aerogel: average particle size of 2 pm, porosity of 92%, bulk density of 25 g / L;

[0136] Ethanol solution: water content of 8 wt%;

[0137] Ethylene glycol;

[0138] PTA (pure terephthalic acid);

[0139] Water;

[0140] Silane coupling agent: methacryloxy silane coupling agent KH570;

[0141] Initiator: ammonium persulfate;

[0142] Catalyst: antimony ethylene glycol;

[0143] Acetic acid;

[0144] Amphiphilic solvent: N-methyl morpholine-N-oxide;

[0145] Bifunctional crosslinking agent: divinyl benzene;

[0146] Displacement agent: ethanol;

[0147] (2) The hydrophilic silica aerogel is soaked in an ethanol solution, first ultrasonic dispersed at a frequency of 40 kHz for 0.8 h and refluxed for 3 h, and then vacuum dried to activate the surface hydroxyl group to obtain a modified hydrophilic silica aerogel; wherein the mass ratio of the hydrophilic silica aerogel to the ethanol solution is 1:20, the soaking temperature is 26°C, the soaking time is 3 h, the vacuum drying temperature is 60°C, and the vacuum drying time is 2 h;

[0148] (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;

[0149] (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;

[0150] (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);

[0151] (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.

[0152] The final 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).

[0153] Example 7

[0154] A method for preparing a core-shell structure silicon-containing polyester aerogel particle, which is basically the same as that of example 6, except that the silane coupling agent in step (1) is vinyl silane coupling agent A-151.

[0155] The final 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).

[0156] Example 8

[0157] A method for preparing the core-shell structure 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.

[0158] The finally prepared core-shell structure 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).

[0159] Example 9

[0160] A method for preparing the core-shell structure 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).

[0161] The finally prepared core-shell structure 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).

[0162] Comparative Example 1

[0163] A method for preparing the core-shell structure silicon-containing polyester aerogel particles is substantially the same as that in Example 9, except that no silane coupling agent is added in step (3).

[0164] The finally prepared core-shell structure 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%.

[0165] Comparing Comparative Example 1 and Example 9, it can be seen that the shear strength of the core-shell structure 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 at the same time, the bifunctional crosslinking agent can covalently crosslink with the polyester, further enhancing the structural stability inside the polyester shell layer, and finally realizing comprehensive improvement of the interface performance, while in Comparative Example 1, due to the lack of the addition of both, the shear strength of the core-shell structure silicon-containing polyester aerogel particles decreases, and the coating rate of the polyester shell layer to the modified hydrophilic silica aerogel decreases.

Claims

1. A method for preparing core-shell structured silicon-containing polyester aerogel particles, characterized in that, Includes the following steps: (a) The hydrophilic silica aerogel was immersed in an ethanol solution to activate the surface hydroxyl groups, thus obtaining a modified hydrophilic silica aerogel. (b) After mixing modified hydrophilic silica aerogel, silane coupling agent, PTA, ethylene glycol, water and other substances, the mixture is heated to hydrolyze the silane coupling agent. 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. Other substances include initiators and catalysts. (c) Adjust the reaction conditions so that PTA and ethylene glycol undergo esterification and polycondensation reactions in sequence.

2. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, The average particle size of the hydrophilic aerogel is 1-3µm, the porosity is greater than 90%, and the bulk density does not exceed 28.5g / L.

3. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, The silane coupling agent is one or more of the following: epoxy silane coupling agent, amino silane coupling agent, methacryloxy silane coupling agent, vinyl silane coupling agent, and 3-carboxypropyltrimethoxy silane.

4. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, In step (a), the water content of the ethanol solution is 3-15 wt%, the mass ratio of hydrophilic silica aerogel to ethanol solution is 1:10-20, the soaking temperature is 25-30℃, and the soaking time is 2-3 h.

5. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, 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, the pH value of the system is adjusted to 4-5, the heating temperature is 60-100℃, and the heating time is 5-6 hours.

6. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, In step (b), other substances 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.

7. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, 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 a mixture of PTA, ethylene glycol and water, and then the silane coupling agent and other substances are added, wherein the ultrasonic frequency is 30-50kHz.

8. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, In step (c), the reaction conditions for esterification are: temperature 240-260℃, pressure 0.1MPa, and time 2-3h; the conditions for polycondensation are: temperature 270-290℃, pressure below 100Pa, and time 3-4h.

9. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 1, characterized in that, It also includes step (d): after cooling the reaction system of step (c) to 120-150℃, add a bifunctional crosslinking agent and keep it warm for 1-2 hours; the mass of the bifunctional crosslinking agent added in step (d) is 0.5-2% of the total mass of PTA and ethylene glycol in step (b).

10. The method for preparing core-shell structured silicon-containing polyester aerogel particles according to claim 9, characterized in that, It also includes step (e): after the solid product of step (d) is replaced in the displacement agent, it is taken out and dried sequentially at 25°C for 1-2 h, at 50°C for 2-3 h, and at 80°C for 2-3 h.

11. A core-shell structured silicon-containing polyester aerogel particle, characterized in that, The silica-containing polyester aerogel particles with a core-shell structure are prepared by the method described in any one of claims 1 to 10. The shear strength of the silica-containing polyester aerogel particles with a core-shell structure is not less than 9.4 MPa, the average coating rate of the polyester shell on the modified hydrophilic silica aerogel is not less than 68%, and the thermal conductivity is not higher than 0.025 W / (m·K).

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