CN117165102A - Silicon dioxide dispersoid and preparation method and application thereof - Google Patents

Abstract

The invention discloses a silicon dioxide dispersoid and a preparation method and application thereof; the silica dispersion comprises the following components in parts by mass per 100 parts of silica dispersion: 5-20 parts of modified silicon dioxide and 80-95 parts of ethylene glycol; the modified silicon dioxide is prepared by modifying silicon dioxide by a hydrophilic modifier and an oleophylic modifier, wherein the hydrophilic modifier is a copolymer obtained by polymerizing acrylamide derivatives, sodium styrene sulfonate and maleic anhydride, and the oleophylic modifier is an oleophylic silane coupling agent. According to the invention, the hydrophilic modifier and the lipophilic modifier are adopted to sequentially modify the silicon dioxide, so that hydrophilic groups are partially grafted on the surface of the silicon dioxide, and lipophilic groups are partially grafted on the surface of the silicon dioxide; the hydrophilic group can enable the silicon dioxide to be stably dispersed in the glycol, the prepared dispersoid can not generate phenomena of sedimentation, agglomeration, coarsening and the like in the storage or transportation process, and the lipophilic group can enable the silicon dioxide to improve the compatibility of the silicon dioxide and the polymer in the polyester polymerization, so that the silicon dioxide can be uniformly dispersed in the polyester.

Description

Silica dispersion and preparation method and application thereof

Technical field

The invention relates to the technical field of fine chemicals, and specifically relates to a silica dispersion, its preparation method and its application in in-situ polymerization of polyester.

Background technique

In my country, synthetic fibers containing more than 85% polyethylene terephthalate are called polyester fibers, and their trade name is polyester. Polyester is a polymer obtained by condensation of polybasic acid and polyol. The polyester synthesis process includes direct esterification method and transesterification method. Since the direct esterification method has the advantages of low raw material consumption and short reaction time, it has become the main synthesis process. . The main reaction process of the direct esterification method is: first, use high-purity terephthalic acid and ethylene glycol to esterify to generate ester and water, and then perform polycondensation reaction of the generated ester to obtain polyester and ethylene glycol. The polycondensation includes pre- Polycondensation and final polycondensation. Polyester fiber is a typical hydrophobic fiber with a moisture regain rate of only about 0.4%. Moreover, polyester fiber generally has a smooth surface and has a non-porous structure. When used as a material, it has poor wearing comfort and is prone to feeling stuffy when worn in hot and humid conditions.

New fiber materials characterized by high performance, multi-function, lightweight, and flexibility provide an important path for increasing the value of the textile industry and meet the upgraded consumer demands for functionality, fashion, and greenness. Silica is added to polyester fiber and then treated with alkali to form micropores on the surface of the fiber, giving the fiber the ability to absorb moisture and dry quickly. The three invention patents disclosed by Suzhou Jinhui Fiber New Materials Co., Ltd. (publication numbers are CN104746171A, CN104746172A, CN104746173A) are to add nano-silica to hemp charcoal polyester fiber, coffee charcoal polyester fiber, and hemp charcoal polyester In the fiber, the silica is then removed by alkali washing to obtain polyester fiber with pores, which improves the adsorption and moisture absorption capacity of the fiber.

There are a variety of hydroxyl groups on the surface of silica, such as spontaneous hydroxyl groups, associated hydroxyl groups, twin hydroxyl groups, etc. Adjacent hydroxyl groups are bonded to each other by hydrogen bonds. The hydrogen atoms of isolated hydroxyl groups are highly positively charged and are easily adsorbed to negatively charged atoms. The surface hydroxyl groups are The presence makes the surface chemically active and forms hydrogen bond adsorption when it meets water molecules. The smaller the particle size, the larger the particle specific surface area, the higher the surface energy, and the stronger the cohesion. It is in a thermodynamically unstable state and the particles are more likely to agglomerate. After reducing the particle size through physical and mechanical methods, it is also necessary to add surfactants or perform surface treatment on the particles, so that they are not prone to coarsening or agglomeration during subsequent storage, or are incompatible with the polymer matrix during use. The phenomenon. Among the three invention patents disclosed by Suzhou Jinhui Fiber New Materials Co., Ltd. (publication numbers are CN104746171A, CN104746172A, CN104746173A), hemp charcoal/coffee charcoal/hemp charcoal, silane coupling agent, and nanoscale silica powder are directly Dispersion, specifically attaching nanoscale silica to the surface pores of hemp charcoal/coffee charcoal/hemp straw charcoal. Without pre-treatment of nanoscale silica, the silica is unevenly dispersed in the fiber.

The Chinese patent with the publication number CN102330188A discloses a method for preparing nano-silica modified polyester fiber. Terephthalic acid and ethylene glycol are added to the slurry kettle for pulping, and then nano-silica and nano-silica are added to the slurry kettle for pulping. Zirconium dioxide and matting agent titanium dioxide are added into the beating kettle to undergo esterification and polycondensation to obtain nano-modified polyester chips. The technology used in this patent is to add nano-silica directly to polymerized monomers for polymerization. However, the method of directly adding nano-silica cannot be fully dispersed in ethylene glycol and easily agglomerates during the polymerization and esterification processes. It cannot be dispersed well in polyester slices and cannot reflect the nano-structure. The effects and properties of materials.

Ye Renji, majoring in materials physics and chemistry at Donghua University, in his 2005 graduate thesis "Research on the Industrialization of Nanosilica-Modified PET Fiber": Different nanoparticles were proportioned and stirred by high-speed shearing to make them Evenly and stably dispersed in ethylene glycol, and then esterification reaction of ethylene glycol and terephthalate, and then through condensation polymerization, still can obtain PET/nano-silica chips with nanometers evenly dispersed in it, and then melt spinning Silk. This method uses high-speed shearing to disperse nanosilica into ethylene glycol. However, this method can only disperse the silica briefly, but after the shearing force stops, the nanoparticles will aggregate, agglomerate, and Return to coarse phenomenon.

The Chinese patent with publication number CN1760443A discloses a method for preparing polyester nanocomposite materials that can be used for deep-dyed fibers. Nanosilica is used as an added modifier. First, it is organically surface modified to make it evenly dispersed in the fiber. In one of the polyester polymerization monomers, ethylene glycol, the prepared nano-silica/ethylene glycol dispersion is added into the reaction kettle during the esterification process, and polymerized with another polyester monomer. In the process, polyester nanocomposite material is obtained, and after high-temperature melt spinning, the polyester nanocomposite fiber is finally formed; this method greatly improves the dye uptake rate by adding nanometer silica particles in the polymerization reaction. The nanosilica is surface-modified by organic coating, and the organic coating uses one or more organic modifiers and coupling agents to modify the surface. However, the use of organic modifiers or coupling agents cannot well improve the dispersion of nanosilica in ethylene glycol or polyester.

The surface of silica particles is generally hydrophilic and highly polar. It is easy to combine with moisture in the air and easily agglomerate, resulting in reduced dispersibility, and the formed agglomerates are not easy to disperse in organic media with weak polarity. It is also not easy to physically adsorb with organic media. In order to improve the dispersion performance of silica, commonly used modifiers include silane coupling agents, organohalogenated silanes, silazane, siloxane organosilicon compounds, alcohols and organic polymers. In the prior art, it is not known to use hydrophilic modifiers and lipophilic modifiers to modify silica successively and use it in the in-situ polymerization of polyester to improve the compatibility and dispersion of silica and polyester, thereby improving the Related reports on the hygroscopic and quick-drying properties of polyester fiber.

Contents of the invention

In order to solve the above technical problems, the purpose of the present invention is to provide a silica dispersion and its preparation method and application; the present invention uses a hydrophilic modifier and a lipophilic modifier to successively modify the silica to make the silica dispersion The surface of silica is partially grafted with hydrophilic groups and partially grafted with lipophilic groups; the hydrophilic groups enable the silica to be stably dispersed in ethylene glycol, and the prepared dispersion will not settle during storage or transportation. , agglomeration, coarsening and other phenomena, the lipophilic group can improve the compatibility of silica with the polymer during polyester polymerization, and thus can be evenly dispersed in the polyester.

In order to achieve the above technical objectives and achieve the above technical effects, the present invention is implemented through the following technical solutions:

A silica dispersion, based on parts by mass, contains the following components per 100 parts of silica dispersion: 5 to 20 parts of modified silica, 80 to 95 parts of ethylene glycol; wherein, The modified silica is prepared by modifying silica with a hydrophilic modifier and a lipophilic modifier. The hydrophilic modifier is obtained by polymerizing acrylamide derivatives, sodium styrene sulfonate, and maleic anhydride. copolymer, the lipophilic modifier is a lipophilic silane coupling agent.

Further, the acrylamide derivative has a structure represented by general formula (I):

In the general formula (I), R ₁ , R ₂ and R ₃ are the same or different, and each is independently selected from H or methyl; R ₄ is one of an alkyl group and an aromatic hydrocarbon group; M is Na, K, H one of them. Preferably, the acrylamide derivative is selected from the group consisting of 2-acrylamide-2-methylpropanesulfonic acid, sodium 2-acrylamide-2-methylpropanesulfonate, sodium 4-acrylamidobenzenesulfonate, p- Sodium methacrylamide benzene sulfonate.

Preferably, the lipophilic silane coupling agent is selected from the group consisting of phenyltrimethoxysilane, phenyltriethoxysilane, benzyltriethoxysilane, dodecyltrimethoxysilane, and dodecyltriethoxysilane. At least one of ethoxysilane and octadecyltrimethoxysilane.

Further, the silica is nano-silica prepared by a gas phase method, with a particle size of 50 to 100 nm.

The invention further provides a preparation method of the silica dispersion, which includes the following steps:

(1)Hydrophilic modification

Using acrylamide derivatives, sodium styrene sulfonate, and maleic anhydride as raw materials, and using potassium persulfate and sodium bisulfite as initiators, the polymerization reaction is heated under the protection of an inert gas to obtain a hydrophilic modifier; Add a silica aqueous solution to the water modifier to perform a hydrophilic modification reaction. After the reaction, filter, wash, and dry to obtain hydrophilic silica;

(2) Lipophilic modification

The lipophilic modifier is added to the aqueous solution of hydrophilic silica, and the reaction is heated under the protection of inert gas. After the reaction, the modified silica is obtained by filtering, washing, and drying;

(3) Preparation of silica dispersion

Mix the modified silica and ethylene glycol according to the formula amount and disperse them evenly through mechanical stirring to obtain a silica dispersion.

In the above method, the hydrophilic modifier is produced by polymerizing three monomers under the action of an oxidizing agent through unsaturated double bonds; the anhydride group of the hydrophilic modifier reacts with the hydroxyl group of silica, The hydrophilic group is grafted to the silica surface; the methoxy/ethoxy group of the lipophilic modifier reacts with the hydroxyl group of the silica after hydrolysis, and the lipophilic group is grafted to the silica surface.

Further, in step (1), the mass ratio of the acrylamide derivative, sodium styrene sulfonate, and maleic anhydride is (1-3): (1-3):1.

Further, in this method, the mass of the hydrophilic modifier is 1 to 3% of the mass of the silica; the mass of the lipophilic modifier is 1 to 3% of the mass of the hydrophilic silica.

Further, in step (1), the heating temperature is 50-70°C, the polymerization reaction time is 2-6h, and the hydrophilic modification reaction time is 1-4h; in step (2), the heating temperature is 70-90°C. ℃, reaction time is 1 ~ 4h.

The present invention further provides the application of silica dispersion in in-situ polymerization of polyester. Specifically, the silica dispersion is added during the polyester polymerization process. The timing of addition can be during esterification, precondensation, and final polycondensation. During or before reaction. The silica dispersion of the present invention is modified silica dispersed in ethylene glycol. Ethylene glycol can be used as a raw material for polyester esterification, so the silica dispersion is preferably added before the esterification reaction.

The specific preparation process of polyester fiber: raw materials such as silica dispersion, polyterephthalic acid, ethylene glycol and oxidant are subjected to esterification, pre-polycondensation, and final polycondensation to obtain a polyester melt, and then spinning to obtain polyester Fibers; silica is removed by alkali washing to form micropores on the surface of polyester fibers.

The beneficial effects of the present invention are:

The present invention uses a hydrophilic modifier and a lipophilic modifier to modify the silica successively, so that the surface of the silica is partially grafted with hydrophilic groups and partially grafted with lipophilic groups; the hydrophilic groups can make the silica surface Silicon is stably dispersed in ethylene glycol, and the prepared silica dispersion will not cause sedimentation, agglomeration, coarsening, etc. during storage or transportation; the lipophilic group can improve the performance of silica during polyester polymerization. Compatibility with polymers enables the silica to be evenly dispersed in polyester.

There is no cross-linking or self-polymerization of hydroxyl groups on the surface of modified silica, and the viscosity of the system is reduced. Moreover, the sulfonated styrene-maleic anhydride in the hydrophilic modifier can reduce the viscosity of the system, thereby improving the silica dispersion. The solid content of acrylamide derivatives can not only improve the dispersion of silica in water, but also improve the mechanical properties of polyester fibers.

The silica dispersion of the present invention has low viscosity, high solid content, small particle size and good storage stability. It is used in the in-situ polymerization of polyester. After the polyester fiber is alkali dissolved, the micropores on the fiber surface are evenly dispersed, and the fiber surface is uniformly dispersed. The breaking strength and elongation at break have not changed significantly, and the dripping water diffusion time is short, the evaporation rate is high, and it has good moisture absorption and quick-drying properties.

Description of drawings

Figure 1 is an SEM image of No. 1 microporous polyester fiber corresponding to the embodiment of the present invention.

Detailed ways

The technical solutions in the present invention will be clearly and completely described below with reference to specific embodiments. Obviously, the described embodiments are only some, not all, of the embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts fall within the scope of protection of the present invention.

The invention provides a silica dispersion. In terms of parts by mass, every 100 parts of the silica dispersion contains the following components: 5 to 20 parts of modified silica and 80 to 95 parts of ethylene glycol. ; Among them, modified silica is prepared by modifying silica with a hydrophilic modifier and a lipophilic modifier. The hydrophilic modifier is composed of acrylamide derivatives, sodium styrene sulfonate, and maleic anhydride. In the copolymer obtained by polymerization, the lipophilic modifier is a lipophilic silane coupling agent.

Among them, the acrylamide derivative has the structure represented by the general formula (I):

In the general formula (I), R ₁ , R ₂ and R ₃ are the same or different, and each is independently selected from H or methyl; R ₄ is one of an alkyl group and an aromatic hydrocarbon group; M is Na, K, H one of them.

The acrylamide derivatives are preferably 2-acrylamide-2-methylpropanesulfonic acid, sodium 2-acrylamide-2-methylpropanesulfonate, sodium 4-acrylamidobenzenesulfonate, and p-methacrylamide One of the sodium benzenesulfonates.

The lipophilic silane coupling agent is preferably phenyltrimethoxysilane, phenyltriethoxysilane, benzyltriethoxysilane, dodecyltrimethoxysilane, dodecyltriethoxysilane, At least one type of octadecyltrimethoxysilane.

The silica is nano-silica prepared by a gas phase method, with a particle size of 50 to 100 nm.

The invention further provides a preparation method of the silica dispersion, which includes the following steps:

(1)Hydrophilic modification

The mass ratio of acrylamide derivative, sodium styrene sulfonate, and maleic anhydride is (1 to 3):

(1~3): 1. Use potassium persulfate and sodium bisulfite as initiators, heat to 50~70°C under the protection of inert gas, and polymerize for 2~6 hours to obtain a hydrophilic modifier; then perform the hydrophilic modification process Add aqueous silica solution to the modifier and continue the reaction for 1 to 4 hours. After the reaction, filter, wash, and dry to obtain hydrophilic silica; the mass of the hydrophilic modifier is 1 to 3% of the mass of the silica;

(2) Lipophilic modification

Add the lipophilic modifier to the aqueous solution of hydrophilic silica, heat to 70-90°C under the protection of inert gas, react for 1-4 hours, filter, wash and dry to obtain modified silica after the reaction; Among them, the mass of the lipophilic modifier is 1 to 3% of the mass of the hydrophilic silica;

(3) Preparation of silica dispersion

Mix the modified silica and ethylene glycol according to the formula amount and disperse them evenly through mechanical stirring to obtain a silica dispersion.

In the above method, the hydrophilic modifier is produced by polymerizing three monomers under the action of an oxidizing agent through unsaturated double bonds; the anhydride group of the hydrophilic modifier reacts with the hydroxyl group of silica, The hydrophilic group is grafted to the silica surface; the methoxy/ethoxy group of the lipophilic modifier reacts with the hydroxyl group of the silica after hydrolysis, and the lipophilic group is grafted to the silica surface.

The present invention further provides the application of silica dispersion in in-situ polymerization of polyester. Specifically, the silica dispersion is added during the polyester polymerization process. The timing of addition can be during esterification, precondensation, and final polycondensation. During or before reaction. The silica dispersion of the present invention is modified silica dispersed in ethylene glycol. Ethylene glycol can be used as a raw material for polyester esterification, so the silica dispersion is preferably added before the esterification reaction.

Polyester fiber preparation process: silica dispersion, polyterephthalic acid, ethylene glycol and oxidant and other raw materials are subjected to esterification, pre-polycondensation and final polycondensation to obtain a polyester melt, and then spinning to obtain polyester fiber; Silica is removed by alkaline washing to form micropores on the polyester fiber surface.

The present invention will be further described in detail below through specific examples.

Preparation of modified silica

Example 1

Weigh 0.40g of 2-acrylamide-2-methylpropanesulfonic acid and disperse it in 5ml of ice water. Use NaOH solution to adjust the pH value to 8.0 to obtain solution A; weigh 0.40g of sodium styrenesulfonate and 0.20g of maleic anhydride. Dispersed in 10ml of water, add solution A, then add 0.01g potassium persulfate and 0.01g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours to obtain a hydrophilic modifier; then add 50g containing mass The silica aqueous solution of silica is continued to react for 2 hours, filtered, washed, and dried to obtain hydrophilic silica;

Add 1g of phenyltrimethoxysilane to a hydrophilic silica aqueous solution containing 50g of hydrophilic silica, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash, and dry to obtain modified dioxide. Silicon A1.

Example 2

Weigh 0.20g of 2-acrylamide-2-methylpropanesulfonic acid and disperse it in 5ml of ice water. Use NaOH solution to adjust the pH value to 8.0 to obtain solution A; weigh 0.60g of sodium styrenesulfonate and 0.20g of maleic anhydride. Dispersed in 10ml of water, add solution A, then add 0.01g potassium persulfate and 0.01g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours to obtain a hydrophilic modifier; then add 50g containing mass The silica aqueous solution of silica is continued to react for 2 hours, filtered, washed, and dried to obtain hydrophilic silica;

Add 1g of phenyltriethoxysilane to a hydrophilic silica aqueous solution containing 50g of hydrophilic silica, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash and dry to obtain the modified silica. Silica A2.

Comparative example 1

Weigh 0.80g of 2-acrylamide-2-methylpropanesulfonic acid and disperse it in 10ml of ice water. Use NaOH solution to adjust the pH value to 8.0 to obtain solution A; weigh 0.80g of sodium styrenesulfonate and 0.40g of maleic anhydride. Dispersed in 20 ml of water, add solution A, then add 0.02g potassium persulfate and 0.02g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours to obtain a hydrophilic modifier; then add 50g of carbon dioxide The silica aqueous solution of silicon was continued to react for 2 hours, filtered, washed, and dried to obtain hydrophilic silica.

Add 2g phenyltrimethoxysilane to a hydrophilic silica aqueous solution containing 50g hydrophilic silica, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash, and dry to obtain modified dioxide. Silicon B.

Comparative example 2

Weigh 0.40g of 2-acrylamide-2-methylpropanesulfonic acid and disperse it in 5ml of ice water. Use NaOH solution to adjust the pH value to 8.0 to obtain solution A; weigh 0.40g of sodium styrenesulfonate and 0.20g of maleic anhydride. Dispersed in 10 ml of water, add solution A, then add 0.01g potassium persulfate and 0.01g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours to obtain a hydrophilic modifier; then add 50g of dioxide containing The aqueous silica solution of silicon was continued to react for 2 hours, filtered, washed, and dried to obtain modified silica C1.

Comparative example 3

Weigh 0.80g of 2-acrylamide-2-methylpropanesulfonic acid and disperse it in 10ml of ice water. Use NaOH solution to adjust the pH value to 8.0 to obtain solution A; weigh 0.80g of sodium styrenesulfonate and 0.40g of maleic anhydride. Dispersed in 20 ml of water, add solution A, add 0.02g potassium persulfate and 0.02g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours to obtain a hydrophilic modifier; then add silica with a mass of 50g of silica aqueous solution was continued to react for 2 hours, filtered, washed, and dried to obtain modified silica C2.

Comparative example 4

Add 1g of phenyltrimethoxysilane to a silica aqueous solution with a silica mass of 50g, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash, and dry to obtain modified silica D1.

Comparative example 5

Add 2g of phenyltrimethoxysilane to a silica aqueous solution with a silica mass of 50g, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash, and dry to obtain modified silica D2.

Comparative example 6

Weigh 0.40g sodium styrene sulfonate and 0.20g maleic anhydride and disperse them in 10ml of water, add 0.01g potassium persulfate and 0.01g sodium bisulfite, heat to 56°C in a nitrogen atmosphere, polymerize for 4 hours, and obtain hydrophilic Modifier; then add a silica aqueous solution with a silica mass of 50g, continue the reaction for 2 hours, filter, wash, and dry to obtain hydrophilic silica;

Add 1g of phenyltrimethoxysilane to a hydrophilic silica aqueous solution containing 50g of hydrophilic silica, heat to 80°C in a nitrogen atmosphere, react for 2 hours, filter, wash, and dry to obtain modified dioxide. Silicon D3.

Preparation and testing of silica dispersions

The modified silica prepared in Examples 1-2, Comparative Examples 1-6, and the directly purchased untreated silica (E) were mixed with ethylene glycol according to the mass ratio in Table 1 through mechanical stirring. The dispersion is uniform, and silica dispersions with serial numbers 1 to 11 are obtained.

Table 1. Silica dispersion component mass ratio

The viscosity and particle size of the prepared silica dispersions No. 1-10 were tested, and the viscosity and particle size were tested after storage for 30 days. The test data are shown in Table 2; because the slurry obtained from the silica dispersion No. 11 was in the form of a paste condition, poor liquidity, and no relevant tests have been conducted.

Table 2. Silica dispersion performance test results

It can be seen from the above Table 2 that the silica dispersions No. 1 to 5 have hydrophilic groups grafted on the surface of the silica. The dispersion viscosity of the silica in ethylene glycol is low and the particle size is small. After 30 days of storage, Viscosity and particle size did not change much. Due to the lipophilic groups grafted on the silica surface of No. 6 to 7 silica dispersions, the dispersion viscosity and particle size of silica in ethylene glycol are larger. After 30 days of storage, the viscosity and particle size change. big. Because the hydrophilic modifier does not add acrylamide derivatives to No. 8 silica dispersion, compared with No. 1 silica dispersion, the viscosity and particle size of the silica in ethylene glycol are larger. After 30 days of storage, Viscosity and particle size vary greatly. The silica of No. 9 silica dispersion is a commercial product. Due to the self-crosslinking of the silica, its viscosity and particle size are large; after 30 days of storage, the viscosity and particle size change greatly. Compared with No. 1 silica dispersion, No. 10 silica dispersion has increased silica content, slightly increased viscosity, and little change in particle size; after 30 days of storage, the viscosity and particle size did not change much. The silica of No. 11 silica dispersion is a commercial product. The obtained slurry was in the form of a paste and had poor fluidity. No relevant tests were conducted.

Preparation and performance testing of microporous polyester fiber

Add the silica dispersion numbered 1 to 10 into the polyester reaction vessel (the mass of silica in the silica dispersion accounts for 1% of the total mass of terephthalic acid and ethylene glycol, and the mass of terephthalic acid and ethylene glycol. The molar ratio of dicarboxylic acid and ethylene glycol is 1:1.2, and the mass of the catalyst tetrabutyl titanate accounts for 0.2% of the mass of terephthalic acid). After esterification (reaction temperature 265°C, reaction pressure 150kPa), precondensation ( Reaction temperature: 260°C, reaction pressure: 3kPa), final polycondensation (reaction temperature: 265°C, reaction pressure: 100Pa), to obtain a polyester melt. The polyester fiber was obtained by spinning at a temperature of 255°C and a winding speed of 4500 m/min. The polyester fiber is alkaline washed in a sodium hydroxide solution with a concentration of 1 mol/L at 100°C for 120 minutes, and then washed with water and dried to obtain microporous polyester fibers numbered 1 to 10. The microporous polyester fibers No. 1 to 10 and the conventional polyester fiber No. 11 (no silica dispersion is added during polymerization) were tested according to the following method:

Breaking strength and elongation at break: refer to GB/T 14344-2022 Chemical fiber filament tensile properties test method;

Dripping water diffusion time and evaporation rate: refer to GB/T 21655.1-2008 Evaluation of moisture absorption and quick-drying properties of textiles - Part 1: Single combination test method.

The test results are shown in Table 3.

Table 3. Polyester fiber performance test results

Polyester fiber serial number 1 2 3 4 5 6 7 8 9 10 11 Breaking strength (cN/dtex) 3.9 4.0 2.4 2.5 2.4 2.3 2.1 2.2 2.6 3.8 4.2 Elongation at break (%) 35 36 twenty three 25 twenty four twenty three twenty one twenty one 27 34 39 Dripping water diffusion time (s) 0.3 0.3 4.5 4.6 4.8 5.1 5.2 4.7 4.2 0.3 6.6 Evaporation rate (g/h) 1.06 1.06 0.16 0.17 0.15 0.15 0.14 0.15 0.21 1.05 0.11

Modified silica A1 or A2 is added to the polymerization of No. 1, No. 2 and No. 10 polyester fibers, and the content in the polyester fiber is the same. The breaking strength, breaking productivity, dripping diffusion time, and evaporation rate of the two fibers basically the same.

Compared with No. 11 polyester fiber, the breaking strength and breaking productivity of No. 1, No. 2 and No. 10 fibers are basically the same. The dripping diffusion time is short and the evaporation rate is high. It can be seen that the silica dispersion prepared by the present invention is used in polyester fiber. In the fiber, it improves the moisture absorption and perspiration performance of the fiber and has little effect on the mechanical properties of the fiber.

Compared with No. 1 polyester fiber, No. 3 to No. 5 polyester fibers have poorer breaking strength, breaking productivity, dripping diffusion time, and evaporation rate. This is due to the fact that the silica in the No. 3 to No. 5 silica dispersions is in the polyester fiber. The poor dispersion properties in ester synthesis result in poor fiber mechanical properties and moisture absorption and perspiration performance.

Compared with No. 1 polyester fiber, No. 6 to No. 7 polyester fiber has poorer breaking strength, breaking productivity, dripping diffusion time, and evaporation rate. This is due to the poor dispersion performance of No. 6 to No. 7 silica dispersion. There is also not good dispersion in the ester polymerization, resulting in poor fiber mechanical properties and moisture wicking properties.

Compared with No. 1 polyester fiber, No. 8 polyester fiber has poorer breaking strength, breaking productivity, dripping diffusion time, and evaporation rate. This is because the modifier of No. 8 silica dispersion does not contain acrylamide derivatives. Silica dispersions are also relatively poorly dispersed.

Compared with No. 1 polyester fiber, the commercially available silica used in No. 9 polyester fiber has poor dispersion properties in ethylene glycol and polyester. The breaking strength, fracture productivity, and The dripping water diffusion time and evaporation rate are poor.

The above are only examples of the present invention, and do not limit the patent scope of the present invention. Any modifications or equivalent transformations made using the contents of the description of the present invention, or directly or indirectly applied to other related technical fields, all include the same. Within the scope of patent protection of the present invention.

Claims (10)

1. A silica dispersion, characterized in that, in terms of parts by mass, every 100 parts of silica dispersion contains the following components: 5 to 20 parts of modified silica, 80 to 95 parts of ethanol Diol; wherein, the modified silica is prepared by modifying silica with a hydrophilic modifier and a lipophilic modifier, and the hydrophilic modifier is composed of an acrylamide derivative, sodium styrene sulfonate , a copolymer obtained by polymerizing maleic anhydride, and the lipophilic modifier is a lipophilic silane coupling agent. 2. The silica dispersion according to claim 1, characterized in that the acrylamide derivative has a structure represented by general formula (I): In the general formula (I), R ₁ , R ₂ and R ₃ are the same or different, and each is independently selected from H or methyl; R ₄ is one of an alkyl group and an aromatic hydrocarbon group; M is Na, K, H one of them. 3. Silica dispersion according to claim 1, characterized in that the acrylamide derivative is selected from the group consisting of 2-acrylamide-2-methylpropanesulfonic acid, 2-acrylamide-2-methyl One of sodium propane sulfonate, sodium 4-acrylamide benzene sulfonate, and sodium p-methacrylamide benzene sulfonate. 4. The silica dispersion according to claim 1, wherein the lipophilic silane coupling agent is selected from the group consisting of phenyltrimethoxysilane, phenyltriethoxysilane, and benzyltriethoxysilane. At least one of silane, dodecyltrimethoxysilane, dodecyltriethoxysilane, and octadecyltrimethoxysilane. 5. The silica dispersion according to claim 1, characterized in that the silica is nano-silica prepared by a gas phase method. 6. A method for preparing the silica dispersion according to any one of claims 1 to 5, characterized in that it includes the following steps: (1)Hydrophilic modification Using acrylamide derivatives, sodium styrene sulfonate, and maleic anhydride as raw materials, and using potassium persulfate and sodium bisulfite as initiators, the polymerization reaction is heated under the protection of an inert gas to obtain a hydrophilic modifier; Add a silica aqueous solution to the water modifier to perform a hydrophilic modification reaction. After the reaction, filter, wash, and dry to obtain hydrophilic silica; (2) Lipophilic modification The lipophilic modifier is added to the aqueous solution of hydrophilic silica, and the reaction is heated under the protection of inert gas. After the reaction, the modified silica is obtained by filtering, washing, and drying; (3) Preparation of silica dispersion Mix the modified silica and ethylene glycol according to the formula amount and disperse them evenly through mechanical stirring to obtain a silica dispersion. 7. The preparation method of silica dispersion according to claim 6, characterized in that, in step (1), the mass ratio of the acrylamide derivative, sodium styrene sulfonate, and maleic anhydride is (1 ~3): (1~3):1. 8. The preparation method of silica dispersion according to claim 6, characterized in that the mass of the hydrophilic modifier is 1 to 3% of the mass of silica; the mass of the lipophilic modifier is hydrophilic. 1 to 3% of the mass of reactive silica. 9. The preparation method of silica dispersion according to claim 6, characterized in that, in step (1), the heating temperature is 50-70°C, the polymerization reaction time is 2-6h, and the hydrophilic modification reaction The time is 1 to 4 hours; in step (2), the heating temperature is 70 to 90°C, and the reaction time is 1 to 4 hours. 10. Application of the silica dispersion according to any one of claims 1 to 5 in in-situ polymerization of polyester.