CN105442098B - A kind of toughness SiO of PVP coatings2The preparation method of airsetting glue fiber - Google Patents

Abstract

The invention relates to a method for preparing PVP-coated tough _SiO2 airgel fibers. The preparation method includes: preparing silicate or silanol sol into spinning stock solution; adding acidic solution into the coagulation tank as a coagulation bath; adding the spinning stock solution into the coagulation bath for reaction wet spinning to obtain raw silicon Acid/silicate fiber, winding, aging, washing to neutrality, solvent replacement, and drying; the dried fiber is immersed in PVP aqueous solution, taken out, and dried to obtain the product. The method used in the present invention has the characteristics of cheap and easy-to-obtain raw materials, simple reaction process, and good spinnability, and the prepared inorganic _SiO2 airgel fiber has abundant pores, high specific surface area, high temperature resistance, and chemical corrosion resistance , and at the same time the specific surface area of the fiber is adjustable and has a certain toughness, which can expand the application range of the airgel fiber and has more practical value.

Description

A kind of preparation method of tough SiO2 airgel fiber coated with PVP

technical field

The invention belongs to the field of airgel fibers and their preparation, in particular to a method for preparing PVP-coated tough _SiO2 airgel fibers.

Background technique

Aerogel (aerogel) refers to the medium filled in the space network structure in the gel is not a solvent but a gas, a special gel with a solid appearance, because there is almost no solvent component inside, so it is also called xerogel . Airgel is a low-density nanoporous amorphous solid material with a unique structure. The solid phase forms a spatial network structure, and the network structure and the pore structure between the networks are at the nanoscale. Because of its unique structure, airgel also has many unique properties, such as high porosity, high specific surface area, strong adsorption, low density, low acoustic impedance, low thermal conductivity, low refraction, etc.

The high specific surface area of SiO ₂ airgel can provide a large number of reaction/interaction active centers, which is especially beneficial to the processes related to interfacial interaction, such as adsorption, catalysis and electrochemical action; its pores can be used as multifunctional memory and monodisperse Nanoreactor; its special nanopore and its shape bring a rich space and place for interdisciplinary research, such as the diffusion behavior of biomolecules, drug molecules, and reactant molecules in the nanopore, and the contact with the active center Performance, reactivity, etc. are closely related to the pore structure; and the surface effect and quantum size effect brought by its nanoscale network structure make some functionally modified SiO ₂ airgel materials in sensors, lithium It exhibits excellent performance in batteries and nanodevices; its low thermal conductivity makes it have great application prospects in the fields of heat insulation walls, heat insulation windows, and tent heat insulation layers. It is the unique advantages of aerogels in microscopic interface structure and material properties that make them become one of the hotspots in the field of materials research.

The performance of airgel is not only related to its microscopic morphology, but also has an important relationship with the macroscopic morphology of porous composite materials. For SiO ₂ airgel materials, a large number of literatures have reported zero-dimensional powders, two-dimensional films, and three-dimensional blocks, but there are few reports on one-dimensional SiO ₂ airgel fibers. This is mainly because compared with porous materials of other dimensions, fibrous porous materials have more requirements for the preparation of raw materials and preparation conditions. However, fibrous porous materials have excellent properties that other dimensional materials do not possess. Analogous to the porous activated carbon fiber, which is also an inorganic porous fiber, the traditional activated carbon is a porous carbon that has been activated and is in the form of powder or granules, while the activated carbon fiber is in the form of fibers, and the fibers are covered with micropores. The adsorption capacity is several to dozens of times higher than that of granular activated carbon in air, 5 to 6 times higher in aqueous solution, and the adsorption rate is 100 to 1000 times faster. The fiber diameter of the activated carbon fiber is 5-20 μm, the average specific surface area is about 1000-1500 m ² /g, the average pore diameter is 1.0-4.0 nm, and the micropores are evenly distributed on the surface of the fiber. Compared with activated carbon, activated carbon fiber has small and uniform pore size, simple structure, fast adsorption rate for adsorbing small molecular substances, high adsorption speed, and easy desorption. The contact area with the adsorbed substance is large, and it can be evenly contacted and adsorbed, so that the adsorbed material can be fully utilized. High efficiency, and has various fine surfaces such as fiber, felt, cloth and paper, the pores are directly opened on the surface of the fiber, the diffusion path of the adsorbate to the adsorption site is short, and the outer surface area of itself is two orders of magnitude higher than the inner surface area . In terms of air or water purification, the granular or powdery structure is prone to stacking, its adsorption speed is slow, and its separation efficiency is not high. Especially its physical form is inconvenient in application, which limits the scope of application. Activated carbon fiber has small pore size and narrow distribution, fast adsorption speed, large adsorption capacity, and easy regeneration. Compared with powdered (5nm-30nm) activated carbon, activated carbon fiber produces less fine dust during use, and can be made into products in various forms such as yarn, thread, fabric, felt, etc., and is more flexible and convenient to use. However, the massive or membrane-like structure will cause great resistance when air or water passes through, and the pressure difference between before and after filtration is very large. Making SiO ₂ airgel into fiber form will make its performance more excellent.

However, since SiO ₂ airgel is an inorganic material, there are a large number of holes inside it, making SiO ₂ airgel very fragile and brittle. And after making SiO ₂ airgel fiber, it is just easier to break. In order to apply the excellent properties of SiO ₂ airgel fibers in a wider range of fields, it is urgently necessary for me to modify the SiO ₂ airgel fibers to make them stronger.

There is no report on a kind of tough _SiO2 airgel fiber coated with PVP at present.

Contents of the invention

The technical problem to be solved by this invention is to provide a kind of preparation method of PVP-coated tough _SiO2 airgel fiber, which has the characteristics of cheap and easy-to-get raw materials, simple reaction process and good spinnability. A tough SiO ₂ airgel fiber coated with PVP has abundant pores, super high specific surface area, high temperature resistance, and chemical corrosion resistance. The scope of application has more practical value.

In the tough _SiO2 airgel fiber coated with PVP of the present invention, the pores of the airgel fiber are in the nanoscale range, and the specific surface area can be adjusted by changing the preparation conditions.

A kind of toughness SiO that PVP coats of the present invention _The preparation method of airgel fiber, comprising:

(1) Silicate or silanol sol is prepared into spinning stock solution;

(2) Add acidic solution as coagulation bath in coagulation tank;

(3) Add the spinning stock solution in step (1) into the coagulation bath, and perform wet spinning to obtain orthosilicic acid/silicate fiber; the spinning stock solution encounters the coagulation bath acid and undergoes a rapid reaction of strong acid to weak acid Generate solid-phase orthosilicic acid, realize the rapid liquid-solid phase transition required by wet spinning, and form orthosilicic acid/silicate fiber, and sol gelation occurs simultaneously during this process;

(4) Coil the orthosilicic acid/silicate fiber in step (3), then immerse in the aging solution and age at room temperature for 2 to 10 days; make the orthosilicic acid/silicate fiber further undergo sol gelation , realize the transformation from ortho silicic acid/silicate fiber to SiO ₂ fiber, and form a large number of holes at the same time;

(5) washing the fiber aged in step (4) with deionized water to neutrality, using ethanol for solvent replacement, and drying at normal temperature;

(6) After immersing the dried fiber in step (5) in a PVP aqueous solution with a concentration of 5wt% to 15wt% for 5min, take it out, repeat the immersion in PVP and drying operations for 2-5 times, and dry to obtain tough SiO coated with PVP ₂ airgel fibers.

In the step (1), the silicate is sodium water glass, potassium water glass or sodium silicate nonahydrate, and the silanol sol is ethyl orthosilicate, methyltriethoxysilane, methyltrimethoxysilane or Phenyltrimethoxysilane is hydrolyzed into a sol under dilute acid conditions.

In the step (1), the modulus of the spinning stock solution sodium water glass and potassium water glass is 2 to 3, and the Baume degree is 35 to 50. Sodium silicate nonahydrate is directly heated into a solution without further solvent, and the silanol sol The viscosity is 0.01-0.1 Pa·S, and the silicon content is greater than 10wt%.

The acidic solution in the step (2) is a dilute sulfuric acid solution with a concentration of 0.2mol/L to 0.8mol/L, a dilute hydrochloric acid solution with a concentration of 0.4mol/L to 1.2mol/L or a dilute hydrochloric acid solution with a concentration of 12mol/L to 15mol/L L of acetic acid.

The conditions of reaction wet spinning in the step (3) are normal temperature and pressure.

The winding speed in the step (4) is 0.1-2m/s.

The aging solution in the step (4) is to prepare a low-concentration acid solution: a dilute sulfuric acid solution with a concentration of 0.005mol/L～0.1mol/L, a dilute hydrochloric acid solution or a concentration of 0.01mol/L～0.2mol/L It is 0.005mol/L～0.1mol/L oxalic acid.

Drying in the step (6) is freeze drying or supercritical drying.

The invention uses a PVP-coated toughness _SiO2 airgel fiber preparation method, utilizes strong acid to prepare weak acid and sol gelation principle, and prepares _SiO2 airgel fiber by reaction spinning. Then use the surface of a tough SiO ₂ airgel fiber coated with PVP to form a support layer on the surface, thereby preparing a preparation of tough SiO ₂ airgel fiber.

In the present invention, cheap silicate and silicon alcohol sol are mixed with different proportions of cellulose solutions as the spinning stock solution, and different acidic solutions are used as coagulation baths, and the strong acid and weak acid reaction between the silicate and silicon alcohol sol and acid occur and produce The sol is gelled, and orthosilicic acid in the solid phase is partially generated to obtain orthosilicic acid/silicate fibers, and the fibers are wound up by winding rollers. Subsequently, the rolled orthosilicic acid/silicate fiber is soaked in a low-concentration acidic solution for aging, and the fiber is further sol-gelled through the aging process to realize the transformation from orthosilicic acid/silicate fiber to SiO ₂ The fibers are transformed and a large number of holes are formed at the same time. After aging, washing was performed with deionized water, followed by solvent replacement with ethanol. The PVP solution is used to coat the surface of the fiber, and finally a tough SiO ₂ airgel fiber coated with PVP is obtained by freeze-drying or supercritical drying, which is innovative. The prepared tough SiO ₂ airgel fiber coated with PVP has more outstanding advantages in the fields of catalysis, adsorption, filtration, heat preservation, clothing, etc., has a very huge potential demand, and is practical.

In the present invention, after drying at room temperature, immerse the fiber in the PVP solution for 5 minutes, take it out, dry, and repeat the immersion in PVP and drying operations 5 times. A tough SiO ₂ airgel fiber coated with PVP is finally obtained by freeze-drying or supercritical drying the fiber soaked in PVP. The method used in the present invention has the characteristics of cheap and easy-to-obtain raw materials, simple reaction process, and good spinnability, and the prepared inorganic _SiO2 airgel fiber has abundant pores, high specific surface area, high temperature resistance, and chemical corrosion resistance , and at the same time the specific surface area of the fiber is adjustable and has a certain toughness, which can expand the application range of the airgel fiber and has more practical value.

Beneficial effect

The method used in the present invention has the characteristics of cheap and easy-to-obtain raw materials, simple reaction process, and good spinnability, and the prepared inorganic _SiO2 airgel fiber has abundant pores, high specific surface area, high temperature resistance, and chemical corrosion resistance , and at the same time the specific surface area of the fiber is adjustable and has a certain toughness, which can expand the application range of the airgel fiber and has more practical value.

Description of drawings

Fig. 1 is the tenacity SiO that PVP is coated among the embodiment ₁ Airgel fiber knotting physical figure;

Fig. 2 is the SEM figure of the tenacity SiO that PVP coats in embodiment ₁ airgel fiber surface topography;

Fig. 3 is the SEM picture of the pore morphology of the tough SiO ₂ airgel fiber coated with PVP in Example 1.

detailed description

Below in conjunction with specific embodiment, further illustrate the present invention. It should be understood that these examples are only used to illustrate the present invention and are not intended to limit the scope of the present invention. In addition, it should be understood that after reading the teachings of the present invention, those skilled in the art can make various changes or modifications to the present invention, and these equivalent forms also fall within the scope defined by the appended claims of the present application.

Example 1

Sodium water glass with a modulus of 2 and 50 Baume degrees was used as the spinning stock solution, and 0.8 mol/L dilute sulfuric acid solution was used as the coagulation bath to carry out reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 0.1 m/s. The wound fibers were immersed in 0.005 mol/L dilute sulfuric acid for 10 days for aging to realize the transformation from orthosilicic acid/silicate fibers to SiO ₂ fibers, and at the same time, a large number of holes were formed. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, and repeat the immersion in PVP and drying operations 5 times. Finally, after freeze-drying, a tough SiO ₂ airgel fiber coated with PVP is obtained. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 483.2 m ² /g, a most probable pore diameter of 8 nm, and the fiber can be knotted. The obtained PVP-coated tenacity _SiO2airgel fiber knotting physical figure is shown in Figure 1; the SEM image of the PVP-coated tenacity SiO2airgel fiber surface morphology is shown in Figure ₂ shown; the SEM image of the hole morphology of the tough SiO ₂ airgel fiber coated with PVP is shown in Figure 3.

Example 2

Potassium water glass with a modulus of 3 and 35 degrees Baume was used as the spinning stock solution, and 0.2mol/L dilute sulfuric acid solution was used as the coagulation bath to carry out reactive wet spinning. The orthosilicic acid/sodium silicate fiber formed in the coagulation bath was wound at a winding speed of 0.5 m/s. The wound fibers were immersed in 0.005 mol/L dilute sulfuric acid for 10 days for aging to realize the transformation from orthosilicic acid/silicate fibers to SiO ₂ fibers, and at the same time, a large number of holes were formed. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fiber in 5wt% PVP aqueous solution for 5 minutes, take it out, and repeat the immersion in PVP and drying operations 4 times. Finally, freeze-dried to obtain tough SiO ₂ airgel fibers coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 352.4 m ² /g, a most probable pore diameter of 7 nm, and the fiber is bendable.

Example 3

Potassium water glass with a modulus of 3 and 35 degrees Baume was used as the spinning stock solution, and 0.8 mol/L dilute sulfuric acid solution was used as the coagulation bath to carry out reactive wet spinning. The orthosilicic acid/potassium silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.1 mol/L dilute sulfuric acid for 5 days for aging to realize the transformation from ortho silicic acid/silicate fibers to SiO ₂ fibers, while forming a large number of holes. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fiber in 15wt% PVP aqueous solution for 5 minutes, take it out, and repeat the immersion in PVP and drying operation 3 times. Finally, freeze-dried to obtain tough SiO ₂ airgel fibers coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 316.4 m ² /g, a most probable pore diameter of 8 nm, and the fiber can be knotted.

Example 4

The solution obtained by direct heating of sodium silicate nonahydrate is used as the spinning stock solution, and the 0.4mol/L dilute hydrochloric acid solution is used as the coagulation bath for reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 2 m/s. The wound fiber was immersed in 0.01mol/L dilute hydrochloric acid for 10 days for aging, and the transformation from orthosilicic acid/sodium silicate fiber to _SiO2 fiber was realized, and a large number of holes were formed at the same time. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fibers in 10wt% PVP aqueous solution for 5 minutes, take them out, and repeat the immersion in PVP and drying operations twice. Finally, freeze-dried to obtain tough SiO ₂ airgel fibers coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 182.9 m ² /g, a most probable pore diameter of 10 nm, and the fiber is bendable.

Example 5

The solution obtained by direct heating of sodium silicate nonahydrate is used as the spinning stock solution, and the 1.2mol/L dilute hydrochloric acid solution is used as the coagulation bath for reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.2 mol/L dilute hydrochloric acid for 2 days for aging to realize the transformation from ortho silicic acid/sodium silicate fibers to SiO ₂ fibers, while forming a large number of holes. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, and repeat the immersion in PVP and drying operations 5 times. Finally, freeze-dried to obtain tough SiO ₂ airgel fibers coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 207.7 m ² /g, a most probable pore diameter of 10 nm, and the fiber is bendable.

Example 6

The sol with a viscosity of 0.01Pa·S and a silicon content of 12wt% was hydrolyzed with ethyl orthosilicate and dilute hydrochloric acid as the spinning stock solution, and 12mol/L acetic acid solution was used as the coagulation bath to carry out reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.005mol/L oxalic acid for 10 days for aging, and the transformation from orthosilicic acid fibers to SiO ₂ fibers was realized, and a large number of holes were formed at the same time. After aging, the fibers were washed with deionized water until neutral. Solvent replacement was performed with ethanol and dried at normal temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, and repeat the immersion in PVP and drying operations 5 times. Finally, through supercritical drying, the tough SiO ₂ airgel fiber coated with PVP is obtained. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 384.1 m ² /g, a most probable pore diameter of 4 nm, and the fiber can be knotted.

Example 7

Methyltriethoxysilane was hydrolyzed with dilute hydrochloric acid to form a sol with a viscosity of 0.05 Pa·S and a silicon content of 18wt% as the spinning stock solution, and 15mol/L acetic acid solution as the coagulation bath for reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.1mol/L oxalic acid for 5 days for aging to realize the transformation from orthosilicic acid fibers to SiO ₂ fibers and to form a large number of holes at the same time. After aging, the fibers were washed with deionized water until neutral. The solvent in the fibers was replaced with absolute ethanol and dried at room temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, repeat the immersion in PVP and drying operation 5 times, and undergo supercritical drying to obtain the tough _SiO2 airgel fiber coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 592.5 m ² /g, a most probable pore diameter of 4 nm, and the fiber can be knotted.

Example 8

Methyltrimethoxysilane was hydrolyzed with dilute hydrochloric acid to form a sol with a viscosity of 0.1Pa·S and a silicon content of 22wt% as the spinning stock solution, and 15mol/L acetic acid solution as the coagulation bath for reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.1mol/L oxalic acid for 5 days for aging to realize the transformation from orthosilicic acid fibers to SiO ₂ fibers and to form a large number of holes at the same time. After aging, the fibers were washed with deionized water until neutral. The solvent in the fibers was replaced with absolute ethanol and dried at room temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, repeat the immersion in PVP and drying operation 5 times, and undergo supercritical drying to obtain the tough _SiO2 airgel fiber coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 629.4 m ² /g, a most probable pore diameter of 4 nm, and the fiber can be knotted.

Example 9

Using phenyltrimethoxysilane plus dilute hydrochloric acid hydrolyzed into a sol with a viscosity of 0.08 Pa·S and a silicon content of 20wt% was used as the spinning stock solution, and 15mol/L glacial acetic acid solution was used as the coagulation bath to carry out reactive wet spinning. The orthosilicic acid/silicate fiber formed in the coagulation bath was wound at a winding speed of 1 m/s. The wound fibers were immersed in 0.1mol/L oxalic acid for 5 days for aging to realize the transformation from orthosilicic acid fibers to SiO ₂ fibers and to form a large number of holes at the same time. After aging, the fibers were washed with deionized water until neutral. The solvent in the fibers was replaced with absolute ethanol and dried at room temperature. After drying, immerse the fiber in 10wt% PVP aqueous solution for 5 minutes, take it out, repeat the immersion in PVP and drying operation 5 times, and undergo supercritical drying to obtain the tough _SiO2 airgel fiber coated with PVP. The prepared tough SiO ₂ airgel fiber coated with PVP has a specific surface area of 536.4 m ² /g, a most probable pore diameter of 4 nm, and the fiber can be knotted.

Claims (4)

1. A kind of 1. toughness SiO of PVP coatings₂The preparation method of airsetting glue fiber, including：

   (1) silicate is configured to spinning solution；Wherein, silicate is sodium silicate, KP1 or nine water sodium metasilicate, spinning The specification of stoste is：Sodium silicate, the modulus of KP1 are 2~3, and Baume degrees is 35~50, and nine water sodium metasilicate directly heat Into solution without solubilizer again；

   (2) acid solution is added in coagulating basin as coagulating bath；Wherein, acid solution be concentration be 0.2mol/L~ The dilute hydrochloric acid solution or concentration that 0.8mol/L dilution heat of sulfuric acid, concentration are 0.4mol/L~1.2mol/L be 12mol/L~ 15mol/L acetic acid；

   (3) spinning solution in step (1) is added in coagulating bath, carries out reaction wet spinning, part generates the former silicon of solid phase Acid, obtain orthosilicic acid/silicate fiber；

   (4) orthosilicic acid in step (3)/silicate fiber is wound, is then immersed in normal temperature in aged solution and is aged 2~10 days； Wherein, aged solution be concentration be 0.005mol/L~0.1mol/L dilution heat of sulfuric acid, concentration be 0.01mol/L~ 0.2mol/L dilute hydrochloric acid solution or concentration is 0.005mol/L~0.1mol/L oxalic acid；

   (5) fiber after being aged in step (4) is washed with deionized to neutrality, using ethanol progress solvent displacement, and Dried under normal temperature；

   (6) after dried fiber in step (5) being immersed into concentration for 5min in the 5wt%~15wt% PVP aqueous solution, take Go out, repeat to immerse PVP, dry, obtain the toughness SiO of PVP coatings₂Airsetting glue fiber.
2. A kind of 2. toughness SiO of PVP coatings according to claim 1₂The preparation method of airsetting glue fiber, it is characterised in that The condition of reaction wet spinning is normal temperature and pressure in the step (3).
3. A kind of 3. toughness SiO of PVP coatings according to claim 1₂The preparation method of airsetting glue fiber, it is characterised in that The speed of winding is 0.1~2m/s in the step (4).
4. A kind of 4. toughness SiO of PVP coatings according to claim 1₂The preparation method of airsetting glue fiber, it is characterised in that Dried in the step (6) as freeze-drying or supercritical drying.