Ultra-thin low-temperature graphene composite fiber and preparation method thereof

Abstract

The invention discloses an ultra-thin low-temperature graphene composite fiber and a preparation method thereof. The raw material components of the ultra-thin low-temperature graphene composite fiber include: modified graphene, microfiber glass wool, chopped fibers and a dispersant, wherein the dispersant includes sulfuric acid and a rosin-based surfactant; the mass ratio of modified graphene: microfiber glass wool: chopped fibers: rosin-based surfactant is (2-4): (93-95): (2-4): (1-3); the modified graphene is prepared by grafting and modifying graphene oxide with PEG, or the modified graphene is prepared by grafting and modifying graphene oxide with polyether; the thickness of the ultra-thin low-temperature graphene composite fiber is ≤0.04mm. The invention effectively solves the problem of uniform dispersion of graphene in glass fiber wool dispersion, and obtains a low-temperature thermal insulation graphene composite fiber with pinholes and concave-convex structures, which has the advantages of excellent mechanical properties, low thermal conductivity, good uniformity, light weight, wide operating temperature range, high yield rate, low energy consumption, etc.

Description

Technical Field

[0001] The invention relates to an ultra-thin low-temperature graphene composite fiber and a preparation method thereof, and belongs to the technical field of graphene composite materials. Background Art

[0002] Graphene, also known as "single-layer graphite sheet", refers to a dense layer of carbon atoms wrapped in a honeycomb crystal lattice. The carbon atoms are arranged in a two-dimensional structure, similar to the single atomic layer of graphite. Compared with carbon nanotubes, graphene has a perfect hybrid structure, and its large conjugated system makes it have a strong electron transmission ability. In addition, the raw material for synthesizing graphene is graphite, which is inexpensive. Due to its unique structure, excellent physical properties and stable chemical properties, graphene has received widespread attention from the scientific community and has been widely used in high-performance micro-nanoelectronic devices, composite materials, field emission materials, gas sensors, energy storage and other fields.

[0003] The boiling point of cryogenic liquid gas is very low, for example, liquid nitrogen is -196℃, liquid oxygen is -183℃, liquid hydrogen is -253℃, and liquid helium is even lower at -268.9℃. With the increasing demand for cryogenic liquids, the application of cryogenic containers such as LNG cryogenic cylinders, storage tanks, cryogenic pipelines, etc. is becoming more and more extensive, accompanied by higher and higher requirements for cryogenic insulation materials. Therefore, the demand for high-quality insulation materials for the storage and transportation of ultra-low temperature liquid gases is becoming increasingly prominent.

[0004] Low-temperature insulation fiber is the main raw material for LNG (liquefied natural gas) cylinders, storage tanks, and tank trucks. After being compounded with aluminum foil, it is wrapped between the inner and outer liner of the cylinders, storage tanks, and tank trucks. After being vacuumed, it can meet the insulation requirements of -269°C to 500°C. It is the latest generation of insulation technology in the world and a new material industry that the country encourages to develop.

[0005] The existing glass fiber low-temperature insulation paper products have a light weight (10-12 grams / square meter), and the tensile strength of the dried products is only 0.03KN / m. At present, the hot air drying technology used in the drying of domestic low-temperature insulation paper products has the disadvantages of complex ovens, high manufacturing costs, and low yields. CN101357979A discloses a low-temperature resistant LNG insulation material and its preparation method. The material is composed of a component A composed of 60-97% mixed polyols, 0.1-2% catalysts, 0.5-10% uniform foaming agents, 2-15% foaming agents, 2-15% flame retardants, and 0.1-5% chain extenders; and then reacted with a component B of isocyanates to obtain the obtained material. The material can be used for a long time at low temperatures above -220°C, has good cold preservation and mechanical properties, can adapt to rapid changes in the temperature range above 300°C, has high flame retardancy, low thermal conductivity, can effectively prevent heat loss of ultra-low temperature liquids, and is an environmentally friendly, energy-saving, pollution-free, high-performance insulation and cold preservation material. However, this material is not suitable for use under high vacuum conditions. The organic material has a high air exchange rate and is not suitable for multi-layer vacuum insulation applications. CN103074799B discloses a super-permeable deep-cold insulation material and a preparation method thereof. The glass fiber paper is prepared using alkali-free glass fiber and water-drawn glass fiber, which has the disadvantages of high thermal conductivity coefficient and reduced strength.

[0006] To this end, this application proposes an ultra-thin low-temperature graphene composite fiber and a preparation method thereof. After scientific research, the applicant has developed a low-temperature graphene composite fiber with pinholes and concave-convex structures, which reduces the user's vacuuming time and is of great significance for saving energy and improving efficiency. The successful development of this product fills the gap of domestic LNG companies' reliance on imported high-end insulation materials from abroad, and lays a solid foundation for localization. At the same time, it has important practical significance and driving role in the development of related emerging industries, especially the further promotion and application of liquefied natural gas, reducing coal and gasoline combustion emissions, saving energy and reducing emissions, improving urban air quality, and improving the living environment and quality of citizens. Summary of the invention

[0007] The present invention provides an ultra-thin low-temperature graphene composite fiber and a preparation method thereof, which effectively solves the dispersion problem of graphene in a glass fiber wool dispersion liquid, obtains a stable dispersion liquid through the modification of graphene and the selection of raw material components such as a dispersant, improves the mechanical properties and yield of the product, shortens the vacuuming time, and reduces energy consumption.

[0008] In order to solve the above technical problems, the technical solutions adopted by the present invention are as follows:

[0009] An ultra-thin low-temperature graphene composite fiber, whose raw material components include: modified graphene, microfiber glass wool, chopped fibers and a dispersant, wherein the dispersant includes sulfuric acid and a rosin-based surfactant; the mass ratio of modified graphene: microfiber glass wool: chopped fibers: rosin-based surfactant is (2-4): (93-95): (2-4): (1-3); the modified graphene is prepared by grafting PEG onto graphene oxide, or the modified graphene is prepared by grafting polyether onto graphene oxide; the thickness of the ultra-thin low-temperature graphene composite fiber is ≤0.06 mm.

[0010] If graphene oxide is used directly, it cannot be evenly dispersed in the glass fiber wool dispersion, and in practice, it will not improve the performance of ultra-thin low-temperature paper. This application modifies graphene oxide through non-ionic surfactant grafting modification, and studies the compatibility of modified graphene with microfiber glass wool and dispersant. The modified graphene is applied to the production process of ultra-thin low-temperature paper, the formula is designed and optimized, and a stable dispersion is formed. At the same time, the tensile strength of the ultra-thin low-temperature paper is improved, the flexibility is increased, the yield rate is improved, and the air extraction rate is improved.

[0011] The present application effectively solves the problem of uniform dispersion of graphene in glass fiber wool dispersion by modifying the surface functional groups of graphene and designing the formula.

[0012] The above-mentioned microfiber glass wool is mainly used as the material, and short-cut fibers are used as the auxiliary material.

[0013] Through the above improvements to the low-temperature insulation paper, the inventor has made the quality of the company's low-temperature insulation paper significantly leading among domestic counterparts.

[0014] When PEG is used to graft-modify graphene oxide, the graphene oxide is firstly subjected to carboxylation treatment and then subjected to PEG graft-modification.

[0015] Since the carboxyl functional groups of graphene oxide (GO) only exist at the edges of GO sheets, and are small and dispersed, the present application first performs carboxylation treatment on graphene oxide, and then performs PEG (polyethylene glycol) grafting modification, which improves the dispersion effect and ensures product performance.

[0016] Through the above-mentioned modification of the surface functional groups of graphene oxide, not only the dispersibility in the glass fiber wool dispersion is significantly improved, but also the mechanical properties and yield rate of the product are improved.

[0017] When PEG is used to graft-modify graphene oxide, the following steps are included:

[0018] 1) drying the graphene oxide in a vacuum oven at 40-50° C. for 10-12 h, and then ultrasonically dispersing it in anhydrous DMSO;

[0019] 2) Under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C., TDI (toluene diisocyanate) is added to the material in step 1) in portions. After TDI is completely added, the reaction is continued under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C. for 20 to 24 hours, and then filtered;

[0020] 3) The filtered solid (solid obtained by filtration) obtained in step 2) is ultrasonically dispersed in anhydrous DMSO, and then a dichloromethane solution of polyethylene glycol 400 is added under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C. The reaction is continued under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C. for 6 to 8 hours, filtered, and dried to obtain modified graphene.

[0021] In the above step 1), the ratio of the mass g of graphene oxide to the volume ml of anhydrous DMSO is (0.0552±0.0005):100;

[0022] In step 2), the ratio of the volume of TDI to the volume of anhydrous DMSO is (0.06±0.01):100; TDI is added in 3 to 4 times, with a time interval of more than 10 minutes between the last addition;

[0023] In step 3), the volume of anhydrous DMSO is equal to the volume of anhydrous DMSO in step 1); the volume of dichloromethane is half the volume of anhydrous DMSO; the ratio of the volume of polyethylene glycol 400 to the volume of anhydrous DMSO is (0.15±0.03):100;

[0024] When polyether is used to graft graphene oxide, graphene oxide is subjected to a catalytic grafting reaction with PO and / or EO in a solvent; wherein the solvent is dimethyl sulfoxide (DMSO) or cyclopentane sulfone, the catalyst is KOH, and the grafting reaction is carried out in a high-pressure reactor. The hydrophilic and hydrophobic properties of non-ionic surface-active graphene can be regulated by controlling the chain length of the grafted PO and EO.

[0025] When polyether is used to graft graphene oxide, the following steps are included:

[0026] 1) drying the graphene oxide in a vacuum oven at 40-50° C. for 10-12 hours, then mixing with a refined solvent and dispersing it evenly under ultrasonic action; the solvent is dimethyl sulfoxide (DMSO) or sulfolane;

[0027] 2) Transfer the dispersion obtained in step 1) to a high-pressure reactor, add KOH, replace with nitrogen three times, and then evacuate at T<90°C (too high temperature will draw out the solvent); at the same time, add PO and / or EO to the PO and / or EO tank;

[0028] 3) Open the valve of the PO and / or EO tank, and let PO and / or EO flow into the autoclave to start stirring reaction. The reaction pressure in the autoclave is controlled to be 0.1-0.2 MPa, and the stirring speed is 100 r / min;

[0029] 4) After the reaction reaches the specified amount of PO and / or EO, ​​the valve of the PO and / or EO tank is closed, and the reaction pressure is reduced to -0.02 MPa, the reaction is completed, the temperature is reduced to 70° C., the material is discharged, and the solvent is removed to obtain modified graphene.

[0030] In the above step 1), the drying temperature is too high and GO is prone to agglomeration.

[0031] In step 2), the mass amount of KOH is 1-2% of the mass of graphene oxide.

[0032] In step 3), when the solvent is dimethyl sulfoxide, the reaction temperature is 90-100°C; when the solvent is sulfolane, when the reactant is PO, the reaction temperature is 120-130°C; when the reactant is EO, the reaction temperature is 110-120°C.

[0033] In step 4), the mass ratio of PO and / or EO to graphene oxide is 1:2 to 8. Preferably, a mixture of PO and EO in a volume ratio of 1:1 is used.

[0034] The rosin-based surfactant is prepared by esterifying rosin with fatty alcohol, adding acrylic acid, condensing with polyethylene glycol, and then esterifying with maleic anhydride.

[0035] The method for preparing the above-mentioned ultra-thin low-temperature graphene composite fiber comprises the following steps:

[0036] 1) Adding modified graphene, microfiber glass wool and chopped fibers to a hydraulic pulper, adding water to disintegrate, and then pumping them to a pulp preparation tank for dilution and adding a dispersant to prepare a 0.1-0.3 wt% slurry, and adding sulfuric acid in an amount to adjust the pH of the slurry to 3-4;

[0037] 2) The slurry pump transports the slurry from the slurry mixing tank to the slag removal equipment, and then flows into the high-level box;

[0038] 3) The pulp in the high-level box flows to the front box by gravity and the size of the valve opening, and then is dehydrated by gravity and negative pressure on the inclined long wire to form a wet paper sheet. The wet paper sheet further absorbs moisture from the wet paper sheet through the negative pressure tank;

[0039] 4) The transfer net guides the wet paper sheets to the gas-fired infrared drying equipment for drying, and then rolls them up to obtain the product.

[0040] The applicant focuses on the research and development of new products, and creatively uses gas infrared drying technology for the entire drying process of glass fiber low-temperature insulation paper. After debugging, the trial production line has produced stable and qualified glass fiber low-temperature insulation paper products.

[0041] The above-mentioned ultra-thin low-temperature graphene composite fiber adopts wet production technology.

[0042] In the above step 3), the water at the bottom of the oblique long net is reused in step 1). The water generated in the negative pressure tank is returned to the water tank at the bottom of the oblique long net by a vacuum pump. The water tank and the white water pool are connected by a pipe, and the white water in the water tank flows back to the white water pool by gravity for standby use.

[0043] Unless otherwise specified, % in this application is by mass, and a percentage greater than 99.999% is regarded as 100%.

[0044] In the present application, PEG is polyethylene glycol; DMSO is dimethyl sulfoxide; TDI is toluene diisocyanate; EO is ethylene oxide; and PO is propylene oxide.

[0045] The operation without particular description of temperature may be performed at room temperature.

[0046] The technologies not mentioned in the present invention are all referred to the prior art.

[0047] The ultra-thin low-temperature graphene composite fiber of the present invention has the following excellent effects:

[0048] 1) Through the modification of graphene surface functional groups and the design of formula, the problem of uniform dispersion of graphene in glass fiber wool dispersion is effectively solved; the tensile strength of ultra-thin low-temperature paper is improved, the flexibility is increased, the yield rate and the air extraction rate are improved, and the static evaporation rate is reduced;

[0049] 2) A low-temperature insulation paper with pinholes and concave-convex structures was obtained, the air extraction speed of which was increased by more than 20% and the air permeability was increased by more than 15% compared with similar products, which significantly shortened the vacuum extraction time and reduced energy consumption.

[0050] 3) Using gas infrared drying, it saves 20% energy compared with ordinary hot air circulation oven, increases the yield by 10%, and is environmentally friendly;

[0051] 4) It has the characteristics of low thermal conductivity, large contact thermal resistance, good uniformity, light weight and wide operating temperature range. It is the preferred super insulation material for cryogenic liquid storage and transportation containers such as liquid oxygen, liquid hydrogen, liquefied natural gas, liquid helium, liquid argon, liquid nitrogen, and cryogenic transmission pipelines. It has great potential in the fields of industry, agriculture, national defense, scientific research, and people's livelihood. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a scanning electron microscope image of the modified graphene of the present invention;

[0053] Figure 2 This is a surface diagram of the ultra-thin low-temperature graphene composite fiber of the present invention;

[0054] Figure 3 This is a scanning electron microscope image of the ultra-thin low-temperature graphene composite fiber of the present invention. DETAILED DESCRIPTION

[0055] In order to better understand the present invention, the content of the present invention is further explained below in conjunction with the embodiments, but the content of the present invention is not limited to the following embodiments.

[0056] Example 1

[0057] Preparation of rosin-based surfactants:

[0058] 500g of rosin (softening point 76°C, acid value 166mg / g, first grade, Jiangxi Huajin) was heated to 150°C, 1g of ZnO was added, and after uniform stirring, 215g of n-octanol was added dropwise, and the mixture was dropped in 1 hour. After the addition was completed, the mixture was kept warm and refluxed for 10 hours. The mixture was vacuumed and the temperature was reduced to 130°C. 0.1g of hydroquinone was added, and 106g of acrylic acid was added dropwise, and the mixture was dropped in 45 minutes. After the addition was completed, the mixture was kept warm and reacted for 3 hours. The temperature was raised to 180°C, 600g of polyethylene glycol 8000 was added, and the mixture was reacted for 21 hours. Then, 170g of maleic anhydride was added, and the mixture was reacted at 180°C for 5 hours. The mixture was cooled to 60°C, and 5g of sodium bisulfite was added and reacted at 60°C for 3 hours to obtain an off-white rosin-based surfactant.

[0059] Example 2

[0060] Preparation of modified graphene (polyether):

[0061] 1) drying graphene oxide (TNGO, purity greater than 99%, Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences) in a vacuum oven at 45° C. for 10 h, then mixing with anhydrous dimethyl sulfoxide, and dispersing under ultrasonication for 10 min to obtain a dispersion, wherein the mass content of graphene oxide in the dispersion is 5.2 mg / 100 ml;

[0062] 2) The dispersion obtained in step 1) is transferred to a high-pressure reactor, KOH is added, and nitrogen is replaced three times, the mass amount of KOH is 1% of the mass of graphene oxide, and then vacuum is evacuated to -0.02MPa at T<90°C; PO and EO are added to PO and EO tanks at the same time;

[0063] 3) Open the valves of the PO and EO tanks, and flow PO and EO into the autoclave at a volume ratio of 1:1 to start stirring reaction. The reaction pressure in the autoclave is controlled to be 0.1 MPa, the stirring speed is 100 r / min, and the temperature is 90°C;

[0064] 4) After the reaction reaches the specified amount of PO and EO (the mass ratio of PO and EO to graphene oxide is 1:5), the valves of the PO and EO tanks are closed. When the reaction pressure drops to about -0.02 MPa, the reaction is completed, the temperature is lowered to 70°C, the material is discharged, and the solvent is removed to obtain modified graphene, such as Figure 1 shown.

[0065] Example 3

[0066] Preparation of modified graphene (PEG):

[0067] 1) drying graphene oxide (TNGO, purity greater than 99%, Chengdu Organic Chemistry Co., Ltd., Chinese Academy of Sciences) in a vacuum oven at 45° C. for 10 h, then mixing with anhydrous dimethyl sulfoxide, and dispersing under ultrasonication for 10 min to obtain a dispersion, wherein the mass content of graphene oxide in the dispersion is 5.5 mg / 100 ml;

[0068] 2) under the protection of nitrogen and in a water bath at 30° C., TDI was added to the material in step 1) in three times, with a time interval of 15 minutes between two adjacent times. After TDI was completely added, the reaction was continued under the protection of nitrogen and in a water bath at 30° C. for 20 hours, and filtered; the ratio of the volume of TDI to the volume of anhydrous dimethyl sulfoxide was 0.06:100;

[0069] 3) The filtered solid obtained in step 2) is then mixed with anhydrous dimethyl sulfoxide (the volume of anhydrous dimethyl sulfoxide in this step is equal to the volume of anhydrous dimethyl sulfoxide in step 1), dispersed under ultrasonic action for 10 minutes, and then, under the protection of nitrogen and in a water bath at a temperature of 30° C., a dichloromethane solution of polyethylene glycol 400 is added (the volume of dichloromethane is half the volume of anhydrous dimethyl sulfoxide in this step, and the ratio of the volume of polyethylene glycol 400 to the volume of anhydrous dimethyl sulfoxide in this step is 0.15:100), and the reaction is continued under the protection of nitrogen and in a water bath at a temperature of 30° C. for 6 hours, filtered, and dried to obtain modified graphene.

[0070] Example 4

[0071] Preparation of ultra-thin low-temperature graphene composite fibers:

[0072] 1) adding modified graphene (prepared in Example 2), microfiber glass wool (average fiber diameter less than 4.5 μm, EWB-39-H JC / T 978-2012) and chopped glass fibers (diameter 9-13 μm, length 3 mm) into a hydraulic pulper, adding water to disintegrate, and then pumping to a pulp preparation tank for dilution and adding a dispersant to prepare a 0.1 wt% slurry (beating degree 60° SR); the dispersant includes sulfuric acid (mass concentration of 70%) and a rosin-based surfactant (prepared in Example 1); the amount of sulfuric acid added is to adjust the pH of the slurry to 3.5, and the mass ratio of modified graphene: microfiber glass wool: chopped fiber: rosin-based surfactant is 3:94:3:2;

[0073] 2) The slurry pump transports the slurry from the slurry mixing tank to the slag removal equipment, and then flows into the high-level box;

[0074] 3) The pulp in the high-level box flows to the front box by gravity and the size of the valve opening, and then is dehydrated on the inclined long wire by gravity and negative pressure (0.05MPa) to form a wet paper sheet. The wet paper sheet further absorbs the moisture in the wet paper sheet through the negative pressure tank (0.05MPa), and the humidity is ≤85% at this time;

[0075] 4) The transfer net guides the wet paper sheets to the gas-fired infrared drying equipment for drying at 115°C, and the product is obtained by rolling it up.

[0076] The above method adopts gas infrared drying, which saves 20% energy compared with the ordinary hot air circulation oven, increases the yield of finished products by 10%, and is environmentally friendly.

[0077] like Figure 2-3 As shown, the ultra-thin low-temperature graphene composite fiber (ultra-thin low-temperature graphene composite fiber paper) obtained above has pinholes and concave-convex structures. The ultra-thin low-temperature graphene composite fiber is compounded with aluminum foil (6-7 μm), wound around the bottle, and covered with an outer shell to evacuate (10 -4 ~10 -5 Pa), a low thermal conductivity insulation layer is obtained, the evaporation rate of the cryogenic liquid is reduced, and a high vacuum degree can be effectively maintained for a long time.

[0078] Ultra-thin low-temperature graphene composite fiber product performance

[0079] Serial number Product Performance unit parameter 1 thickness mm ≤0.02 2 Weight <![CDATA[g / m 2 ]]> 11±1 3 Thermal Weight Loss ％ <0.5 4 Thermal conductivity W / mk <0.0015 5 Tensile Strength kN / m 0.1 6 Moisture content ％ ≤0.5 7 Breathability μm / pa·s 82.3 8 Operating temperature ℃ -300～750 9 Yield ％ 100

[0080] As can be seen from the above table, ultra-thin low-temperature graphene composite fibers were obtained, which have good thermal insulation, strong mechanical properties, and a wide operating temperature range. Due to the improvement of mechanical properties and process steps, a 100% yield rate was achieved, and the air permeability was good, and the air extraction speed was significantly improved. Relying on independent technology, the applicant has built an annual production line of 300 tons of low-temperature new materials. After trial operation, the product is stable.

[0081] Example 5

[0082] Preparation of ultra-thin low-temperature graphene composite fiber: The difference from Example 4 is that the modified graphene is prepared using Example 3, and the rest is reference to Example 4.

[0083] Ultra-thin low-temperature graphene composite fiber product performance

[0084] Serial number Product Performance unit parameter 1 thickness mm ≤0.02 2 Weight <![CDATA[g / m 2 ]]> 12±1 3 Thermal Weight Loss ％ <0.5 4 Thermal conductivity W / mk <0.0015 5 Tensile Strength kN / m 0.08 6 Moisture content ％ ≤0.5 7 Breathability μm / pa·s 78.9 8 Operating temperature ℃ -273～730 9 Yield ％ 100

[0085] Comparative Example 1

[0086] The difference from Example 4 is that graphene oxide is used instead of modified graphene, that is, the graphene oxide modification step is omitted, and the rest is referred to Example 4.

[0087] Composite fiber product performance

[0088] Serial number Product Performance unit parameter 1 thickness mm 0.04 2 Weight <![CDATA[g / m 2 ]]> 12±1 3 Thermal Weight Loss ％ <0.5 4 Thermal conductivity W / mk 0.04 5 Tensile Strength kN / m 0.04 6 Moisture content ％ ≤0.5 7 Breathability μm / pa·s 70.1 8 Operating temperature ℃ -269～700 9 Yield ％ 92.1

[0089] Comparative Example 2

[0090] The difference from Example 4 is that the modified graphene is omitted, and the rest is the same as Example 4.

[0091] Composite fiber product performance

[0092] Serial number Product Performance unit parameter 1 thickness mm 0.04 2 Weight <![CDATA[g / m 2 ]]> 13±1 3 Thermal Weight Loss ％ <0.5 4 Thermal conductivity W / mk 0.02 5 Tensile Strength kN / m 0.03 6 Moisture content ％ ≤0.5 7 Breathability μm / pa·s 46.5 8 Operating temperature ℃ -269～500 9 Yield ％ 86.3

[0093] Comparative Example 3

[0094] The difference from Example 4 is that the rosin-based surfactant is omitted.

[0095] Composite fiber product performance

[0096] Serial number Product Performance unit parameter 1 thickness mm 0.04 2 Weight <![CDATA[g / m 2 ]]> 12±1 3 Thermal Weight Loss ％ <0.5 4 Thermal conductivity W / mk 0.012 5 Tensile Strength kN / m 0.04 6 Moisture content ％ ≤0.5 7 Breathability μm / pa·s 72.3 8 Operating temperature ℃ -269～600 9 Yield ％ 93.2

[0097] Compared with the product without modified graphene, the tensile strength of the product is more than doubled, the vacuuming time is shortened by more than 15%, and the static evaporation rate is reduced by more than 15%. Through the implementation of this project, a major technological breakthrough in the application of new graphene materials in ultra-thin low-temperature paper has been achieved, the modification of graphene surface functional groups and the uniform dispersion of glass fiber cotton dispersion have been solved, and the performance of ultra-thin low-temperature paper has been improved. Compared with domestic and American Rand products, the air permeability is increased by more than 15%.

Claims

1. An ultra-thin low-temperature graphene composite fiber, characterized in that: The raw material components include: modified graphene, microfiber glass wool, chopped fibers and a dispersant, wherein the dispersant includes sulfuric acid and a rosin-based surfactant; the mass ratio of modified graphene: microfiber glass wool: chopped fibers: rosin-based surfactant is (2-4): (93-95): (2-4): (1-3); the modified graphene is prepared by grafting PEG onto graphene oxide, or the modified graphene is prepared by grafting polyether onto graphene oxide; the thickness of the ultra-thin low-temperature graphene composite fiber is ≤0.06 mm; When PEG is used to graft-modify graphene oxide, the following steps are included: 1) drying the graphene oxide in a vacuum oven at 40-50° C. for 10-12 h, and then ultrasonically dispersing it in anhydrous DMSO; 2) Under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C., TDI was added to the material in step 1) in portions. After TDI was completely added, the reaction was continued under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C. for 20 to 24 hours, and then filtered; 3) ultrasonically dispersing the filtered solid obtained in step 2) in anhydrous DMSO, then adding a dichloromethane solution of polyethylene glycol 400 under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C., continuing to react for 6 to 8 hours under the protection of nitrogen and in a water bath at a temperature of 25 to 35° C., filtering and drying to obtain modified graphene; When polyether is used to graft graphene oxide, the following steps are included: 1) drying the graphene oxide in a vacuum oven at 40-50° C. for 10-12 hours, then mixing with a solvent and dispersing the solvent evenly under ultrasonic action; the solvent is dimethyl sulfoxide or cyclopentane; 2) transferring the dispersion obtained in step 1) to a high-pressure reactor, adding KOH, replacing with nitrogen three times, and then evacuating at T<90°C; at the same time, adding PO and / or EO to the PO and / or EO tank; 3) Open the valve of the PO and / or EO tank, and let PO and / or EO flow into the autoclave to start stirring reaction. The reaction pressure in the autoclave is controlled to be 0.1-0.2 MPa, and the stirring speed is 100 r / min; 4) After the reaction is continued until PO and / or EO reach the specified amount, the valve of the PO and / or EO tank is closed, and the reaction pressure is reduced to -0.02 MPa, the reaction is completed, the temperature is reduced to 70° C., the material is discharged, and the solvent is removed to obtain modified graphene; Rosin-based surfactants are prepared by esterification of rosin with fatty alcohols, addition of acrylic acid, condensation with polyethylene glycol, and then esterification with maleic anhydride.

2. The ultra-thin low-temperature graphene composite fiber according to claim 1, characterized in that: When PEG is used to graft-modify graphene oxide, in step 1), the ratio of the mass g of graphene oxide to the volume ml of anhydrous DMSO is (0.0552±0.0005):

100.

3. The ultra-thin low-temperature graphene composite fiber according to claim 1, characterized in that: When PEG is used to graft-modify graphene oxide, in step 2), the ratio of the volume of TDI to the volume of anhydrous DMSO is (0.06±0.01):100; TDI is added in 3 to 4 times, with a time interval of more than 10 minutes between the last addition; In step 3), the volume of anhydrous DMSO is equal to that of anhydrous DMSO in step 1); the volume of dichloromethane is half the volume of anhydrous DMSO; and the ratio of the volume of polyethylene glycol 400 to the volume of anhydrous DMSO is (0.15±0.03):

100.

4. The ultra-thin low-temperature graphene composite fiber according to claim 1, characterized in that: When polyether is used to graft-modify graphene oxide, in step 2), the mass amount of KOH used is 1 to 2% of the mass of graphene oxide.

5. The ultra-thin low-temperature graphene composite fiber according to claim 1, characterized in that: When polyether is used to graft-modify graphene oxide, in step 3), when the solvent is dimethyl sulfoxide, the reaction temperature is 90-100°C; when the solvent is cyclopentane sulfone, when the reactant is PO, the reaction temperature is 120-130°C, and when the reactant is EO, the reaction temperature is 110-120°C.

6. The method for preparing the ultra-thin low-temperature graphene composite fiber according to any one of claims 1 to 5, characterized in that: The steps include: 1) Adding modified graphene, microfiber glass wool and chopped fibers to a hydraulic pulper, adding water to disintegrate, and then pumping them to a pulp preparation tank for dilution and adding a dispersant to prepare a 0.1-0.3 wt% slurry, and adding sulfuric acid in an amount to adjust the pH of the slurry to 3-4; 2) The slurry pump transports the slurry from the slurry mixing tank to the slag removal equipment, and then flows into the high-level box; 3) The pulp in the high-level box flows to the front box by gravity and the size of the valve opening, and then is dehydrated by gravity and negative pressure on the inclined long wire to form a wet paper sheet. The wet paper sheet further absorbs moisture from the wet paper sheet through the negative pressure tank; 4) The transfer net guides the wet paper sheets to the gas-fired infrared drying equipment for drying, and then rolls them up to obtain the product.

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