Synthesis of nano-porous rare earth silicate thermal insulation fiber by co-precipitation method and preparation method thereof

Abstract

The application provides a kind of co-precipitation method synthesis nanometer porous rare earth silicate heat preservation fiber and preparation method thereof, the fiber is prepared by the following components by weight parts through melt spinning process: 2-15 parts of nanometer porous rare earth silicate, 85-98 parts of high molecular polyester chip;Wherein, the chemical formula of nanometer porous rare earth silicate is (La a Ce b Y c Sm d )2Si2O7@KH550, 0 The fabric woven from the fiber has light and thin texture, low thermal conductivity, high tensile strength, and excellent thermal insulation effect.

Description

TECHNICAL FIELD

[0001] The present application belongs to the field of functional fibers, and particularly relates to a kind of nano-porous rare earth silicate thermal insulation fiber synthesized by coprecipitation method and a preparation method thereof. BACKGROUND

[0002] With the continuous prosperity of social economy and the evolution of modern lifestyle, people's interest in outdoor leisure activities is increasing day by day, which not only reflects the improvement of life quality, but also reflects the pursuit of natural experience and health. Consequently, consumers' expectations for functional outdoor textiles have significantly increased, especially products with excellent thermal insulation performance, which not only meet the demand for warmth, but also take into account comfort and durability.

[0003] In view of this, it has become an urgent need in the industry to develop a new type of fiber fabric that not only has excellent thermal insulation effect, but also ensures good tensile strength and excellent thermal insulation performance. Such fabric aims to provide all-round protection for outdoor enthusiasts, so that they can maintain body comfort in cold or hot environments, thereby improving the overall experience of outdoor activities. However, the mainstream thermal insulation fabric on the current market relies on surface coating technology to achieve thermal insulation function. Although this method achieves the expected effect to some extent, coating treatment often leads to heavy fabric texture, and is easily affected by environmental factors such as humidity and temperature changes during long-term use, resulting in decreased weather resistance, affecting the wearing experience and service life.

[0004] To overcome the above limitations, research teams are working to explore innovative solutions, among which thermal insulation fiber fabric made of aerogel silicon oxide, glass beads and thermal expansion balls shows great potential. Although these materials can theoretically provide excellent thermal insulation performance, their particle size is large, making it difficult to process finely, which in turn affects the tensile strength of the fibers, limiting their widespread application in actual products.

[0005] In view of this challenge, in-depth research and technological innovation are particularly crucial. Optimizing material formulations, improving processing techniques, and developing new composite materials will be important ways to break through existing bottlenecks. By precisely controlling material particle size, enhancing fiber bonding, and improving overall fabric structural stability, it is hoped that better performing, more market-demand-oriented thermal insulation fiber fabrics can be created, leading to an innovation trend in the outdoor textile industry. SUMMARY

[0006] Therefore, the present application aims to propose a kind of nano-porous rare earth silicate thermal insulation fiber synthesized by coprecipitation method and a preparation method thereof, to solve the defects of complex preparation process, high cost, high thermal conductivity, poor thermal insulation effect and low tensile strength of rare earth silicate in the prior art.

[0007] To achieve the above object, the technical scheme of the present application is as follows:

[0008] A kind of nano-porous rare earth silicate heat-insulating fiber is synthesized by co-precipitation method, which is prepared by melt spinning process from components including the following weight fractions: 2-15 parts of nano-porous rare earth silicate, 85-98 parts of high molecular polyester chip;Wherein, the chemical formula of nano-porous rare earth silicate is (La a Ce b Y c Sm d )2Si2O7@KH550, 0 < a, b, c, d < 1, and a + b + c + d = 1.

[0009] Further, the nano-porous rare earth silicate is prepared by the following method:

[0010] 1) uniformly disperse 2-10 parts by weight of rare earth chloride salt in 2-10 parts by weight of deionized water to obtain a rare earth chloride salt solution;

[0011] 2) completely dissolve 1-5 parts by weight of sodium silicate and 0.1-3 parts by weight of surfactant in 50-70℃ deionized water in turn to obtain a sodium silicate solution;

[0012] 3) then pour 0.1-5 parts by weight of surfactant solution into the rare earth chloride salt solution, then add an acidic solution to adjust the pH to 2-4, and finally add the sodium silicate solution drop by drop while stirring;

[0013] 4) the system after reaction is filtered, washed and dried to obtain a nano-porous rare earth silicate precursor;

[0014] 5) disperse the nano-porous rare earth silicate precursor in anhydrous ethanol, add a surface modifier and ultrasonic dispersion, and finally filter, freeze and dry to obtain the nano-porous rare earth silicate.

[0015] Further, in step 1), the solid content of the rare earth chloride salt solution is 50-80%, and the temperature is 50-70℃;

[0016] In step 3), the surfactant solution is poured into the rare earth chloride salt solution, the temperature is maintained at 50-70℃, and stirring is carried out for 60-90 minutes;After the sodium silicate solution is added dropwise, the reaction is carried out for 3-5 hours;

[0017] In step 4), the drying temperature is 60-80℃;

[0018] In step 5), ultrasonic dispersion is carried out for 30-60 minutes, and the temperature for freeze-drying is -10℃ to -50℃.

[0019] Further, the rare earth chloride salt is a mixture of lanthanum chloride, yttrium chloride, samarium chloride and cerium chloride.

[0020] Further, the surface active agent is one or a mixture of more than one of citric acid, sodium citrate, sodium dodecyl sulfate, and ethylenediaminetetraacetic acid;

[0021] The acid solution is one or a mixture of more than one of hydrochloric acid, oxalic acid, acetic acid, and citric acid, and the pH value of the acid solution is 1;

[0022] The surface modifier is KH550.

[0023] Further, the dropping speed of the sodium silicate solution is 10-20 mL·min -1 , and the concentration of the sodium silicate solution is 5-15 mol / L.

[0024] Further, the high-molecular polyester chip is one or a mixture of more than one of polyethylene terephthalate, polybutylene terephthalate, polyamide, polyethylene, polyurethane, and polylactic acid.

[0025] The application further provides a preparation method of the nano-porous rare earth silicate thermal insulation fiber synthesized by the co-precipitation method.

[0026] 1) uniformly mixing the nano-porous rare earth silicate and the high-molecular polyester chip, and then drying in an oven to obtain the functional high-molecular polyester chip with a water content of less than 300 ppm;

[0027] 2) putting the functional high-molecular polyester chip obtained in step 1) into a double-screw extruder to perform melt extrusion granulation, and obtaining a thermal insulation master batch;

[0028] 3) preparing a round thermal insulation fiber through a melt spinning process by using the thermal insulation master batch obtained in step 2).

[0029] Further, in step 1), the drying temperature is 65-90 DEG C, and the drying time is 8-15 h;

[0030] In step 2), the temperature for melt extrusion is 150-350 DEG C, and the extrusion speed is 100-300 r / min.

[0031] The application further provides an application of the nano-porous rare earth silicate thermal insulation fiber synthesized by the co-precipitation method to outdoor products, clothes, home textiles, and industrial textiles.

[0032] Compared with the prior art, the nano-porous rare earth silicate thermal insulation fiber synthesized by the co-precipitation method and the preparation method thereof have the following advantages:

[0033] (1) The nano-porous rare earth silicate is synthesized by a co-precipitation method, and the nano-porous rare earth silicate is prepared by adjusting the concentration (solid content) of a rare earth chloride solution, adding a surfactant, and adjusting the pH value of a reaction system, and the preparation method is simple, the particle size is controllable, the yield is large, and the purity is high, and the nano-porous rare earth silicate can be directly used for granulation and spinning.

[0034] 2) The nano-porous rare earth silicate has stable physical and chemical properties, a large specific surface area, and a low thermal conductivity, is an excellent thermal insulation material, and the surface structure of the nano-porous rare earth silicate contains an organic-inorganic bonding agent, so that the nano-porous rare earth silicate can be strongly combined with high polymer polyester chips and is not easy to fall off, and the nano-porous rare earth silicate is beneficial to better thermal insulation effect.

[0035] 3) The nano-porous rare earth silicate is blended with high polymer polyester chips, and thermal insulation fibers are finally formed by melt spinning, thermal insulation fabrics are made by knitting or weaving, and finally, the thermal conductivity, tensile strength, and thermal insulation rate of the fabrics are tested, the thermal insulation fabrics have light and thin texture, low thermal conductivity, high tensile strength, and high thermal insulation rate, and have excellent heat insulation and warm-keeping effects. BRIEF DESCRIPTION OF DRAWINGS

[0036] The accompanying drawings, which form a part of the present application, are used to provide further understanding of the present application, and serve as an appositive explanation of the illustrative embodiments of the present application, and do not constitute improper limitations to the present application. In the drawings:

[0037] Figure 1 It is a schematic diagram of the reaction process of the present application;

[0038] Figure 2 It is an SEM diagram of the nano-porous rare earth silicate prepared in Example 1 of the present application;

[0039] Figure 3 It is an X-ray diffraction diagram of the nano-porous rare earth silicate prepared in Example 1 of the present application. DETAILED DESCRIPTION

[0040] It should be noted that the embodiments in the present application and the features in the embodiments can be combined with each other without conflict.

[0041] The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0042] Example 1

[0043] A nano-porous rare earth silicate thermal insulation fiber is synthesized by a co-precipitation method, which is prepared by a melt spinning process and comprises the following components in parts by weight: 10 parts of nano-porous rare earth silicate, 90 parts of high molecular polyester chips; wherein the chemical formula of the nano-porous rare earth silicate is (La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7@KH550, and the high molecular polyester chips are 45 parts of polyethylene terephthalate and 45 parts of polybutylene terephthalate.

[0044] The nano-porous rare earth silicate is prepared by the following method:

[0045] 1) 6 parts of a mixture of rare earth chloride salts with a molar ratio of 0.25:0.25:0.25:0.25 are dissolved in 4 parts of deionized water to uniformly disperse, to obtain a rare earth chloride salt solution with a solid content of 60% and a temperature of 60°C;

[0046] 2) 2 parts of sodium silicate and 1 part of surfactant sodium citrate are respectively and sequentially completely dissolved in the same part of 60°C deionized water to obtain a sodium silicate solution;

[0047] 3) 1 part of the surfactant sodium citrate solution is poured into the rare earth chloride salt solution, the temperature is kept at 60°C, and stirring is performed for 60 minutes; then an acidic solution with pH = 1 is added to adjust the solution pH to 3, and finally the sodium silicate solution with a concentration of 10 mol / L is added dropwise while stirring for 4 hours, and the dropwise adding speed is 15 mL·min -1 ; the acidic solution is a mixed solution of hydrochloric acid, oxalic acid, acetic acid, and citric acid with a pH value of 1;

[0048] 4) the reaction system is filtered, washed, and dried at 60°C for 12 hours to obtain a nano-porous rare earth silicate precursor;

[0049] 5) the nano-porous rare earth silicate precursor is dispersed in anhydrous ethanol, a surface modifier KH550 (NH2-(CH2)3-Si-(OCH2CH3)3) is added and ultrasonically dispersed for 60 minutes, and finally the system is filtered, frozen at -30°C, and dried to obtain the nano-porous rare earth silicate (La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7@KH550.

[0050] The preparation method of the nano-porous rare earth silicate thermal insulation fiber by the co-precipitation method comprises the following steps:

[0051] 1) Mix nano-porous rare earth silicate and high molecular polyester chip uniformly, and then dry in an oven at 80℃ for 12 hours to obtain functional high molecular polyester chip with water content less than 300ppm;

[0052] 2) Put the functional high molecular polyester chip obtained in step 1) into a double screw extruder, and melt extrude and granulate at 270℃, with water temperature of 70℃, and extrusion speed of 200r / min, to obtain heat preservation master batch finally;

[0053] 3) Dry the heat preservation master batch obtained in step 2) at 120℃ for 12 hours to make water content less than 200ppm, and prepare circular heat preservation fiber through melt spinning process, with spinning temperature of 270℃ and winding speed of 400m / min;

[0054] 4) Finally, prepare heat preservation fiber fabric through weaving or knitting.

[0055] Figure 1 The figure is a schematic diagram of the reaction process of the present application, Figure 2 The figure is a SEM image of nano-porous rare earth silicate prepared in the present embodiment, from which it can be seen that the surface of the nano-porous rare earth silicate is covered by porous structure, Figure 3 The figure is an X-ray diffraction image of nano-porous rare earth silicate prepared in the present embodiment, from which it can be seen that the diffraction peak of the prepared powder is consistent with the standard card of (La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7, i.e. (La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7 is successfully prepared, and the diffraction peak is sharp, indicating good crystallinity and stable physical and chemical properties.

[0056] Example 2

[0057] On the basis of the above embodiment 1, the rare earth chloride salt used for preparing nano-porous rare earth silicate is lanthanum chloride, cerium chloride, yttrium chloride and samarium chloride with molar ratio of 0.35:0.2:0.3:0.15, and the surfactant is sodium dodecyl sulfate, and the others are the same as in embodiment 1.

[0058] Finally, prepare heat preservation fiber fabric through weaving or knitting.

[0059] Example 3

[0060] On the basis of the above-mentioned embodiment 1, the rare earth chloride salt used in the preparation of nanoscale porous rare earth silicate is lanthanum chloride, cerium chloride, yttrium chloride and samarium chloride with a molar ratio of 0.3:0.2:0.4:0.1, and the surfactant is ethylenediaminetetraacetic acid, and the others are the same as in embodiment 1.

[0061] Finally, the thermal insulation fiber fabric is made by weaving or knitting.

[0062] Example 4

[0063] On the basis of the above-mentioned embodiment 1, the rare earth chloride salt used in the preparation of nanoscale porous rare earth silicate is lanthanum chloride, cerium chloride, yttrium chloride and samarium chloride with a molar ratio of 0.4:0.1:0.4:0.1, and the surfactant is citric acid, and the others are the same as in embodiment 1.

[0064] Finally, the thermal insulation fiber fabric is made by weaving or knitting.

[0065] Comparative Example 1

[0066] The difference from embodiment 1 is that the use amount of nanoscale porous rare earth silicate and high molecular polyester chip is different, 1 part of nanoscale porous rare earth silicate, 49.5 parts of polyethylene terephthalate powder and 49.5 parts of polybutylene terephthalate powder are mixed.

[0067] Comparative Example 2

[0068] The difference from embodiment 1 is that the use amount of nanoscale porous rare earth silicate and high molecular polyester chip is different, 20 parts of nanoscale porous rare earth silicate, 40 parts of polyethylene terephthalate powder and 40 parts of polybutylene terephthalate powder are mixed.

[0069] Comparative Example 3

[0070] The difference from embodiment 1 is that the reaction temperature in steps 2) and 3) in the preparation of nanoscale porous rare earth silicate is different:

[0071] 2) Dissolve 2 parts of sodium silicate and 1 part of surfactant sodium citrate in 90℃ deionized water respectively to obtain a sodium silicate solution;

[0072] 3) Pour the surfactant sodium citrate solution into the rare earth chloride salt solution at 80℃, keep at 90℃, stir for 60 minutes, then add an acidic solution to adjust the pH to 3, and finally add the sodium silicate solution drop by drop while stirring, and react for 4 hours after the addition is completed.

[0073] Comparative Example 4

[0074] The difference from embodiment 1 is that in the preparation of nanoscale porous rare earth silicate, an acidic solution is added in step 3) to adjust the pH to 1.

[0075] Comparative Example 5

[0076] The difference from Example 1 is that the rare earth silicate is prepared by a solid phase grinding method, and the specific preparation method is as follows:

[0077] 1) The lanthanum oxide, cerium oxide, yttrium oxide, samarium oxide and silicon oxide are weighed according to the molar ratio of 0.25:0.25:0.25:0.25:2, mixed uniformly, and then deionized water is added to make the solid content 60%;

[0078] 2) The material weighed in step 1) is poured into a ball mill tank, and the ball mill is operated at a speed of 500 r / min for 8 hours, then taken out and poured into a sand mill, and ground to a slurry particle size of 300 nm, and then filtered, washed, and dried at 60°C for 12 hours to obtain a nano rare earth silicate precursor;

[0079] 3) The nano rare earth silicate precursor is dispersed in anhydrous ethanol, and an appropriate amount of surface modifier KH550, i.e. NH2-(CH2)3-Si-(OCH2CH3)3, is added and ultrasonically dispersed for 60 min, and then filtered, freeze-dried to obtain a nano(La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7@KH550.

[0080] 4) The preparation method and the addition ratio of the nano(La 0.25 Ce 0.25 Y 0.25 Sm 0.25 )2Si2O7@KH550 modified insulation fiber are the same as those of Example 1.

[0081] Comparative Example 6

[0082] The difference from Example 1 is that the rare earth chloride salt is lanthanum chloride, cerium chloride and yttrium chloride with a molar ratio of 1 / 3:1 / 3:1 / 3, and the nano porous rare earth silicate is(La 1 / 3 Ce 1 / 3 Y 1 / 3 )2Si2O7.

[0083] Comparative Example 7

[0084] The difference from Example 1 is that the rare earth chloride salt is cerium chloride, yttrium chloride and samarium chloride with a molar ratio of 1 / 3:1 / 3:1 / 3, and the nano porous rare earth silicate is(Ce 1 / 3 Y 1 / 3 Sm 1 / 3 )2Si2O7.

[0085] Comparative Example 8

[0086] The difference from Example 1 is that the rare earth chloride salt is lanthanum chloride, yttrium chloride and samarium chloride in a molar ratio of 1 / 3:1 / 3:1 / 3, and the nano-porous rare earth silicate is (La 1 / 3 Y 1 / 3 Sm 1 / 3 )2Si2O7.

[0087] Comparative Example 9

[0088] The difference from Example 1 is that the rare earth chloride salt is lanthanum chloride, cerium chloride, yttrium chloride and samarium chloride in a molar ratio of 0.5:0.5:0.5:0.5, and the final product is (La 0.5 Ce 0.5 Y 0.5 Sm 0.5 )2Si2O 10 .

[0089] Comparative Example 10

[0090] The difference from Example 1 is that the concentration of the rare earth chloride salt solution is different, and 9 parts of the rare earth chloride salt is dissolved in 1 part of deionized water, with a solid content of 90%.

[0091] Comparative Example 11

[0092] The difference from Example 1 is that no surfactant is added when preparing the nano-porous rare earth silicate.

[0093] Blank fabric

[0094] That is, no nano-porous rare earth silicate is added to the fiber fabric, and the specific preparation method is as follows: (1) 50 parts of polyethylene terephthalate powder and 50 parts of polybutylene terephthalate powder are weighed according to the mass ratio, and after being mixed uniformly, they are dried in an 80°C oven for 12 hours to obtain functional polyester chips with a water content of less than 300 ppm;

[0095] (2) The mixed powder obtained in step (1) is put into a twin-screw extruder for melt extrusion granulation at 270°C, the water temperature of the draw bar is 70°C, the extrusion speed is 200 r / min, and finally the master batch is obtained;

[0096] (3) The master batch obtained in step (2) is dried at 120°C for 12 hours to make the water content less than 200 ppm, and round heat preservation fibers are prepared through a melt spinning process, the spinning temperature is 270°C, the winding speed is 400 m / min, and the fiber fabric is made by shuttle weaving or knitting.

[0097]

[0098] ​The nano-sized porous rare earth silicate prepared in Examples 1-4 was subjected to specific surface area test, and the thermal insulation fiber fabric prepared therefrom was subjected to thermal conductivity, tensile strength and thermal insulation rate test, and the results are shown in Table 1.

[0099] Table 1: Comparison of performance indicators of Examples 1-4 and blank fabric

[0100]

[0101]

[0102] As can be seen from Table 1, the nano-sized porous silicate prepared by coprecipitation has a large specific surface area, which can be up to 488.51 m 2 / g, and the larger the specific surface area, the larger the surface area of the static air layer, which is more conducive to improving the thermal insulation performance of the fabric. The main indicators for measuring the thermal insulation fiber and fabric are thermal conductivity and thermal insulation rate, and the lower the thermal conductivity, the higher the thermal insulation rate, the better the thermal insulation performance of the fabric. Compared with the blank fabric, Examples 1-4 all have very low thermal conductivity and high thermal insulation rate, which reflects excellent thermal insulation performance. In addition, the addition of inorganic components in the fiber generally causes incompatibility, resulting in low tensile strength of the fiber and fabric and easy tearing, which cannot be applied. In Examples 1-4, the surface of the nano-sized porous rare earth silicate is modified, which can connect with inorganic components and be compatible with organic matrix, thereby effectively improving the tensile strength of the fabric. By comparing the tensile strength of Examples 1-4 and the blank fabric, it can be seen that when the addition amount of nano-sized porous rare earth silicate is 10 parts, the tensile strength of the fabric is basically the same as that of the pure fiber fabric.

[0103] The silicates prepared in Comparative Examples 1-11 were subjected to specific surface area test, and Examples 1 and each of the comparative examples were subjected to thermal conductivity, thermal conductivity and thermal insulation test, and the test results are shown in Table 2.

[0104] Table 2: Comparison of performance indicators of each comparative example

[0105]

[0106]

[0107] Comparing the performance of Example 1 and Comparative Examples 1-2, it can be seen that when the addition amount of nano-sized porous silicate is 10 parts, the thermal insulation effect of the fiber fabric is best, and when the addition amount is 1 part, the content of nano-sized porous rare earth silicate in the fiber is low, which is not enough to significantly improve the thermal insulation performance of the fiber fabric, and too much addition may cause agglomeration, resulting in uneven distribution of rare earth silicate, which ultimately leads to a decrease in the thermal insulation performance of the fiber fabric. In addition, too much addition may cause the fiber to agglomerate into large particles, which may weaken the tensile strength of the fiber and limit its application.

[0108] Comparing the performance of Example 1 with that of Comparative Example 3, it can be seen that by adjusting the reaction temperature, a porous rare earth silicate with a larger particle size (smaller specific surface area) can be prepared, and the thermal insulation fiber prepared therefrom has poor thermal insulation and tensile strength, because at the same addition amount, the distribution amount of the large particle size porous silicate is less, the voids are more, in addition, the specific surface area of the large particle size rare earth silicate is small, the static air layer area is small, and under the influence of the two factors, the thermal insulation and tensile strength are poor. In the nano-porous rare earth silicate, the silicon source is sodium silicate, which can be electrolyzed into Na + and SiO3 2+ in aqueous solution. SiO3 2+ is easy to react with H + to generate H2SiO3, reducing the SiO3 2+ content in the solution, and further reducing the yield of rare earth silicate.

[0109] In Comparative Example 4, the pH of the solution is 1, and the H + content in the solution is too high, which reduces the SiO3 2+ content, and further reduces the production yield.

[0110] Comparative Example 5 is a nano-rare earth silicate prepared by a solid phase grinding method. Although the preparation process is relatively simple, only grinding according to the proportion is required, but the preparation process is time-consuming and energy-consuming, and the specific surface area of the finally prepared rare earth silicate is extremely low, and the thermal conductivity of the thermal insulation fiber prepared therefrom is high, and the thermal insulation rate is low.

[0111] Comparing the performance of Example 1 with that of Comparative Examples 6-8, it can be seen that Comparative Examples 6-8 are all ternary nano-porous silicates, and their specific surface areas are similar to those of multi-element nano-porous silicates, but their thermal insulation performance is poorer. This is because the multi-element nano-porous rare earth silicate contains multiple rare earth ions, which increases the mass disorder and bond disorder of the material, thereby reducing the thermal conductivity and improving the thermal insulation performance.

[0112] In Comparative Example 9, adjusting the proportion of rare earth elements in the rare earth silicate may affect the formation and stability of the surface pores of the reaction product. Excessive amount of a certain element may fill or destroy these pores, thereby reducing the porosity of the material, and further weakening its thermal insulation performance. In addition, the excessive amount of a certain element may also cause phase separation in the material, forming a new phase different from the main material. These new phases may have different thermal properties, thereby affecting the thermal insulation effect of the overall material. Phase separation also leads to a decrease in the uniformity of the material, and further affects its long-term performance.

[0113] In Comparative Example 10, the concentration of the rare earth chloride salt solution was increased. At high concentrations, the rare earth ions can locally become supersaturated, which can easily produce by-products or irregular precipitates, thereby affecting the purity of the product. In addition, at high concentrations, both the nucleation rate and the growth rate are accelerated, which can result in the formation of large particle precipitates. These large particles have a small specific surface area, thereby reducing the insulation effect. Furthermore, when these large particles are added to the fibers, the fibers can be more easily broken due to the large particle size, thereby reducing the tensile strength of the fibers.

[0114] In Comparative Example 11, no surfactant was added during the reaction. The resulting rare earth silicate had a large size, the particles were severely agglomerated, the surface properties were unstable, the specific surface area was small, and the fiber tensile strength was low.

[0115] The above description is merely preferred embodiments of the present application, but not to limit the present application. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall fall within the protection scope of the present application.

Claims

1. A nanoporous rare earth silicate thermal insulation fiber synthesized by a co-precipitation method, characterized in that: The application is prepared by a melt spinning process from components comprising the following weight parts: 2-15 parts of nano-sized porous rare earth silicate, 85-98 parts of high molecular polyester chip; wherein the chemical formula of the nano-sized porous rare earth silicate is (La a Ce b Y c Sm d )2Si2O7@KH550, 0 < a, b, c, d < 1, and a + b + c + d = 1. The nanoscale porous rare earth silicate is prepared by the following method: 1) uniformly dispersing 2-10 parts by weight of a rare earth chloride salt in 2-10 parts by weight of deionized water to obtain a rare earth chloride salt solution; the solid content of the rare earth chloride salt solution is 50-80%; 2) completely dissolving 1-5 parts by weight of sodium silicate and 0.1-3 parts by weight of a surfactant in 50-70°C deionized water in sequence to obtain a sodium silicate solution; 3) then pouring the surfactant solution into the rare earth chloride salt solution, keeping the temperature at 50-70°C, then adding an acidic solution to adjust the pH to 2-4, and finally adding the sodium silicate solution drop by drop while stirring; 4) filtering, washing and drying the system after reaction to obtain a nanoscale porous rare earth silicate precursor; 5) dispersing the nanoscale porous rare earth silicate precursor in anhydrous ethanol, adding a surface modifier and ultrasonic dispersion, and finally filtering, freezing and drying to obtain the nanoscale porous rare earth silicate.

2. The nanoporous rare-earth silicate thermal fiber synthesized by the co-precipitation method according to claim 1, characterized in that: In step 1), the temperature is 50-70°C; In step 3), the surfactant solution is poured into the rare earth chloride salt solution and stirred for 60-90 minutes; after the sodium silicate solution is added drop by drop, the reaction is carried out for 3-5 hours; In step 4), the drying temperature is 60-80°C; In step 5), ultrasonic dispersion is carried out for 30-60 minutes, and the freezing and drying temperature is -10°C to -50°C.

3. The co-precipitation method synthesized nanoporous rare earth silicate thermal insulation fiber according to claim 1, characterized in that: The rare earth chloride salt is a mixture of lanthanum chloride, yttrium chloride, samarium chloride and cerium chloride.

4. The co-precipitation method synthesized nanoporous rare earth silicate thermal insulation fiber according to claim 1, characterized in that: The surfactant is a mixture of one or more of citric acid, sodium citrate, sodium dodecyl sulfate and ethylenediaminetetraacetic acid; The acidic solution is a mixture of one or more of hydrochloric acid, oxalic acid, acetic acid and citric acid, and the pH value of the acidic solution is 1; The surface modifier is KH550.

5. The co-precipitation method synthesized nanoporous rare earth silicate thermal insulation fiber according to claim 1, characterized in that: The dropping speed of the sodium silicate solution is 10-20 mL·min -1 The concentration of the sodium silicate solution is 5-15 mol / L.

6. The co-precipitation method synthesized nanoporous rare earth silicate thermal insulation fiber according to claim 1, characterized in that: The high molecular polyester chip is one or more of polyethylene terephthalate, polybutylene terephthalate, polyamide, polyethylene and polyurethane.

7. A method for the preparation of nanoporous rare earth silicate thermal insulation fibers by co-precipitation synthesis according to any one of claims 1 to 6, characterized in that: The method comprises the following steps: 1) uniformly mixing the nanoscale porous rare earth silicate and the high molecular polyester chip, and then drying in an oven to obtain a functional high molecular polyester chip with a water content of less than 300 ppm; 2) putting the functional high molecular polyester chip obtained in step 1) into a twin-screw extruder for melt extrusion and granulation to obtain a heat preservation master batch; 3) preparing a round heat preservation fiber through a melt spinning process using the heat preservation master batch obtained in step 2).

8. The method of claim 7, wherein the method of synthesizing nanoporous rare earth silicate thermal fibers by co-precipitation is characterized by: In step 1), the drying temperature is 65-90°C, and the drying time is 8-15h; In step 2), the melt extrusion temperature is 150-350°C, and the extrusion speed is 100-300r / min.

9. Use of the nanoscale porous rare earth silicate heat preservation fiber synthesized by the coprecipitation method according to any one of claims 1-6 in outdoor products, clothing, home and industrial textiles.

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