Modified fiber fabric and preparation method therefor

Abstract

The present invention belongs to the technical field of cellulose. Disclosed are a modified fiber fabric and a preparation method therefor, which solve the technical problem in the prior art of sodium and potassium remaining on a water-absorbing material in CMC-H modified fiber products and thus affecting the biocompatibility of the water-absorbing material. In the modified fiber fabric and the preparation method therefor provided by the present invention, the fiber fabric raw material sequentially modified into carboxymethyl cellulose and subjected to an ammoniation treatment with ammonia gas on the basis of maintaining a fibrous shape, so as to obtain the fiber fabric with ammonium carboxymethyl cellulose as the modified material; the fiber fabric raw material is subjected to a modification treatment reaction on the basis of maintaining the fibrous shape, specifically, during the modification treatment reaction, in fiber molecules of the fiber fabric raw material, 1,4-glucosidic bonds in glucose molecules are linked to form parallel cellulose chains without changing, and specific chemical groups occupying specific carbon positions C6, C2 and C3 on the molecular chains of fibers are subjected to a modification reaction, thereby ensuring the softness and physical properties of the product paper or non-woven fabric.

Description

Modified fiber fabric and preparation method thereof TECHNICAL FIELD

[0001] The present application relates to the technical field of cellulose, in particular to a modified fiber fabric and a preparation method thereof. BACKGROUND

[0002] The water-absorbing materials on the market include ordinary water-absorbing materials and high-molecular water-absorbing materials. The ordinary water-absorbing materials such as paper and cotton fabrics are difficult to be widely applied due to their limited water-absorbing capacity. In comparison, the high-molecular water-absorbing materials are more widely applied in the fields of health care, medical treatment, industry, agriculture and forestry, etc. Among them, the water-absorbing pads made of superabsorbent resin have superior water-absorbing performance and water-retaining property. However, the polypropylene-based superabsorbent resin has poor biodegradability, which easily causes pollution to groundwater and soil environment. Therefore, people have begun to study environmentally friendly water-absorbing materials.

[0003] Cellulose is a long-chain natural polymer in which D-glucose monomers are connected by dehydration in the form of a beta-1,4-glucoside bond. The hydroxyl group at the C6 position is a primary alcohol hydroxyl group, while the hydroxyl groups at the C2 and C3 positions are secondary alcohol hydroxyl groups. The water-absorbing material prepared from cellulose has good degradability and biocompatibility. The hydroxyl group H on C2, C3 and C6 of cellulose is substituted by carboxymethyl to make a CMC-H transition material with relatively small water absorption, and then the corresponding water-absorbing material is obtained by alkalization. The existing CMC-H material made by papermaking or non-woven has sodium ions or potassium ions combined to the unreacted sodium hydroxide, sodium carbonate or potassium hydroxide, which will remain on the water-absorbing material, affecting the biocompatibility of the water-absorbing material, and making it difficult to be well applied in the fields of health care, medical treatment, etc.

[0004] Carboxymethyl cellulose ammonium is another derivative material prepared from cellulose. The existing preparation methods of carboxymethyl cellulose ammonium, such as the preparation method of carboxymethyl cellulose ammonium disclosed in patent application No. CN201110457650.5 and the preparation method of high-viscosity carboxymethyl cellulose ammonium disclosed in patent application No. CN202011249366.4, are all in the form of powder as product, which is usually used as an adhesive for special purposes, mainly for high-quality SCR denitration catalysts. In addition, in addition to the fiber water-absorbing material itself, the water absorption also relies on the "capillary phenomenon" between the fibers, that is, the water will move along the fiber gap due to the capillary phenomenon after the water contacts the gap between the fibers, and part of the water will fill the gap between the fibers. The powder-like carboxymethyl cellulose ammonium has a smaller water-absorbing feature of "capillary phenomenon". Therefore, in the existing technology, carboxymethyl cellulose ammonium is difficult to be utilized as a cellulose water-absorbing material. SUMMARY

[0005] The present application provides a kind of reaction design ingenious, maintain the reaction smoothly at the same time, spare the problem of uncombined non-volatile sodium ion, potassium ion residue, to improve the preparation efficiency and product purity of carboxymethyl cellulose ammonium water-absorbing material, the carboxymethyl cellulose ammonium water-absorbing material obtained has excellent water absorption, water retention, biodegradability and biocompatibility, can be better applied in the modified fiber fabric of health care, medical, industrial, forestry and other fields and its preparation method and application.

[0006] To achieve the above object, the present application is realized by the following technical scheme: the modified fiber fabric provided by the present application is based on maintaining the fiber shape, and is sequentially treated by modification to carboxymethyl cellulose, ammonium treatment with ammonia gas, to obtain a modified fiber fabric with carboxymethyl cellulose ammonium.

[0007] The fiber fabric raw material is modified by maintaining the fiber shape, and specifically, in the modification reaction process, the 1,4-glycosidic bond (i.e., the connection between C1 and C4) in the glucose molecule in the fiber molecule of the fiber fabric raw material does not change, and the specific chemical groups occupying specific carbon positions C6, C2 and C3 on the molecular chain of the fiber are modified.

[0008] Preferably, the degree of substitution of the fiber fabric treated by ammonium with ammonia gas to carboxymethyl cellulose ammonium is 0.2-3.0, the end modification group of the specific chemical groups on carbon positions C6, C2 and C3 in the carboxymethyl cellulose ammonium molecule includes -CH2COONH4, the content range is limited to 4.3%-58.9%, and -CH2COONH4 is directly connected to the glucose unit of the fiber, and the breaking strength of the fiber in the carboxymethyl cellulose ammonium fiber fabric is not less than 60% of the breaking strength of the fiber in the fiber fabric raw material.

[0009] Preferably, the cellulose fiber is natural cellulose fiber and / or regenerated cellulose fiber; the length of the cellulose fiber is not less than 0.5 mm. The cellulose fiber can be natural cellulose fiber such as cotton, hemp, bamboo and straw, or regenerated cellulose fiber such as viscose, tencel, cuprammonium rayon and modal, or a mixture of the above two types of fibers, which has a wide range of applications, abundant raw material sources and good market prospects.

[0010] Preferably, in the modification process to carboxymethyl cellulose, the fiber shape of the cellulose fiber is maintained, and alkalization and etherification are sequentially performed, followed by the addition of acid solution and mixing, the volume percentage concentration of acid in the acid solution is ≥29%, and the modified product obtained after acidification reaction is carboxymethyl cellulose CMC-H.

[0011] The application relates to a preparation method of modified fiber fabric, which is based on keeping the fiber shape and sequentially subjected to modification treatment of carboxymethyl cellulose, ammonia ammoniation treatment, and then obtains the modified fiber fabric with carboxymethyl cellulose ammonium.

[0012] The fiber fabric raw material is subjected to modification treatment reaction while keeping the fiber shape, and specifically, in the modification treatment reaction process, the 1,4-glycosidic bond (i.e. the connection between C1 and C4) in the glucose molecule in the fiber molecule of the fiber fabric raw material is not changed, and a specific chemical group on the specific carbon positions C6, C2 and C3 on the molecular chain of the fiber is subjected to modification reaction.

[0013] Preferably, the fiber fabric raw material is cellulose fiber, and the length of the cellulose fiber is not less than 0.5 mm.

[0014] In the modification treatment of carboxymethyl cellulose, the fiber shape is kept, and alkalization and etherification are sequentially performed, and then acid liquor is added and uniformly mixed; the volume percentage concentration of the acid in the acid liquor is greater than or equal to 29%, and the modified product is carboxymethyl cellulose CMC-H obtained after acidification reaction.

[0015] After washing, the washed fiber is obtained.

[0016] The prepared washed fiber is subjected to ammonia ammoniation treatment by using ammonia gas, and then the modified fiber fabric with carboxymethyl cellulose ammonium is obtained.

[0017] The degree of substitution of the fiber fabric with carboxymethyl cellulose ammonium obtained through ammonia ammoniation treatment is 0.2-3.0, the end modification group of the specific chemical group on the carbon positions C6, C2 and C3 in the carboxymethyl cellulose ammonium molecule includes -CH2COONH4, the content range of which is limited to 4.3%-58.9%, and -CH2COONH4 is directly connected with the glucose unit of the fiber, and the breaking strength of the fiber fabric with carboxymethyl cellulose ammonium is not less than 60% of the breaking strength of the fiber in the fiber fabric raw material.

[0018] Preferably, after the pH of the washing residual liquid is greater than or equal to 4.0, the washed fiber is obtained.

[0019] Preferably, the post-treatment drying step in the ammonia ammoniation treatment step is heating drying, the fiber fabric after ammoniation is heated and dried, the obtained heat synchronously removes the uncombined ammonia gas in the reaction, and the heating and drying is performed until the water content in the fiber fabric with carboxymethyl cellulose ammonium is less than or equal to 15%, at this time, the drying is step-by-step control of the water content to be less than or equal to 15%, which can reduce the deformation of the fiber caused by excessive water loss in a short time to a certain extent, so that the carboxymethyl cellulose ammonium water absorption material with more excellent mechanical strength is obtained.

[0020] Preferably, in the ammonia treatment step with ammonia gas, the fabric is first prepared and then subjected to the ammonium treatment step. This fabric preparation method has more operability, more applicable processes, less drying steps, and higher production efficiency. Specifically, the method comprises the following steps:

[0021] The washed fiber is first made into a primary fabric by a papermaking or non-woven process, and then the primary fabric is subjected to ammonium treatment with ammonia gas to obtain an ammoniated fiber fabric.

[0022] Preferably, in the process of making the washed fiber into a primary fabric,

[0023] When the fabric is prepared by papermaking, the washed fiber is first dispersed uniformly in pure water or a common fiber-water dispersion before being subjected to papermaking to prepare the fabric. The weight ratio of the washed fiber to the common fiber is 10-100:90-0. In the papermaking step, the total amount of the washed fiber and the common fiber is 0.3-1.5 wt% for papermaking, and the single-layer thickness of the paper is 7-30 g / m 2 . If the fiber content is too low and the thickness is too small, the primary fabric obtained has a high breakage rate. If the fiber content is too high and the thickness is too large, it will affect the drying efficiency and effect of the subsequent primary fabric. Therefore, the product performance is optimal when the preparation method of the present application uses the above papermaking parameters.

[0024] When the fabric is prepared by a non-woven process, the washed fiber is first mixed with the common fiber before being subjected to non-woven to prepare the fabric. The weight ratio of the washed fiber to the common fiber is 10-100:90-0. In the non-woven step, the washed fiber and the common fiber are reinforced into a non-woven fabric by mechanical, thermal bonding or chemical methods, and the grammage is 9-600 g / m 2 . The non-woven process can choose various processing methods such as hot rolling, water jet, needle punching, etc. The hot rolling process has a lower grammage, and the needle punching process has a higher grammage. Therefore, the grammage of the present application can be adjusted within the range of 9-600 g / m 2 according to different process needs.

[0025] The papermaking of the present application is to uniformly disperse the water-washed fibers and then to perform papermaking; the non-woven is to arrange the water-washed fibers in a direction or randomly to form a web structure, and then to reinforce by using a mechanical method, a thermal bonding method or a chemical method. Preferably, the common fiber is one or more of bamboo fiber, cotton fiber, wood fiber, hemp fiber, regenerated cellulose fiber, polylactic acid fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester, acrylic fiber, polypropylene fiber and ES fiber. The water-washed fiber of the present application can be prepared into a pure carboxymethyl cellulose ammonium fiber sheet according to the need, or can be prepared into a composite fiber sheet by cooperating with other common fibers. The pure carboxymethyl cellulose ammonium fiber sheet has more excellent water absorption and water retention rate; and the composite fiber sheet has more excellent physical properties due to the incorporation of other common cellulose. The addition of common fibers enhances the physical properties and processability, and the natural cellulose can increase the support of the water-washed fiber; the regenerated cellulose fiber can be cut to a length according to the need before processing, so as to increase the tensile properties of the water-absorbing material; and the added polylactic acid fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester, acrylic fiber, polypropylene fiber and ES fiber all have thermoplasticity, which expands the types of non-woven processes.

[0026] Preferably, in the ammonia treatment step using ammonia gas, the ammonia treatment is performed first, and then the papermaking step is performed, specifically as follows:

[0027] The water-washed fiber is first preliminarily dried, and then the ammonia gas is used to ammoniate the water-washed fiber to generate a CMC-NH4 fiber, and then the uncombined ammonia gas is removed by heating the air duct, and the obtained fiber dry material is uniformly laid and then needled to obtain an ammoniated fiber sheet.

[0028] Preferably, the acid is a biocompatible acid, and the specific acid is one or more of acetic acid, citric acid, hydrochloric acid, nitric acid and formic acid.

[0029] Preferably, the acidification is a multiple acidification operation, until the fiber acidification reaction is fully sufficient, and the total acidification time is 0.8h-1.5h. By the multiple acidification operation, it can be further ensured that the whole fiber is in a high-concentration acid for effective and sufficient acidification, and thus the acidification reaction is fully sufficient.

[0030] Preferably, the acid liquor further comprises an alcohol in a volume percentage concentration of 0-50%; the alcohol is one or more of methanol, ethanol, and isopropanol. In the step of preparing CMC-H, when the acid concentration is low, the water contained therein has a certain swelling and solubility to the CMC-Na that is not sufficiently acidified, and it is difficult to better maintain the fiber form. In combination with the feature that the fiber is difficult to dissolve in alcohol and can maintain the fiber form, the addition of an appropriate amount of alcohol in the present application can better inhibit the swelling and dissolution of the fiber, so as to better maintain the cellulose in the fiber form. If the acid concentration is high in the step of preparing CMC-H, the degree of swelling and dissolution of the fiber is low at this time, and the addition of alcohol can be omitted. The use of methanol, ethanol, and isopropanol is common low-boiling-point alcohol, which has good mutual solubility with water, has less interference to cellulose, and is also convenient for subsequent impurity removal.

[0031] Preferably, the ammonia gas is obtained by evaporating liquid ammonia, ammonia water, or ammonia-alcohol water at a temperature of 0-130 DEG C and a pressure of 102 kPa to less than the liquefied vapor pressure of ammonia gas at the corresponding temperature. The above liquid ammonia, ammonia water, or ammonia-alcohol water are all volatilized to generate ammonia gas under the set temperature and pressure; when the pressure is less than 102 kPa, the pressure is slightly lower than the basic atmospheric pressure, and even if the ammoniation container is emptied of air and filled with ammonia gas, it is difficult to uniformly reach the initial formed fiber, resulting in uneven reaction; the upper limit of the pressure is less than the liquefied vapor pressure of ammonia gas at the corresponding temperature, because after the liquefaction of ammonia gas, the fiber is directly dissolved into the liquid, and it is difficult to maintain the fiber form, so that the subsequent product is hardened. On the other hand, when the temperature is lower than 0 DEG C, the penetration of ammonia gas is poor and difficult to combine; when the temperature is greater than 130 DEG C, it is close to the carbonization temperature of cellulose, and is easy to cause the strength of the fiber to decrease.

[0032] The water-absorbing material can be well applied in the fields of health care, medical treatment, industry, agriculture, forestry, etc. The modified fiber fabric prepared by the above method has good water-absorbing property, and also has good biodegradability and biocompatibility, and can be widely applied in the fields of health care, medical treatment, industry, agriculture, forestry, etc.

[0033] The present application provides a modified fiber fabric and a preparation method thereof.

[0034] (1) The modified fiber fabric and the preparation method thereof adopt cellulose fiber as raw material, and the whole process is modified and treated in the form of fiber, and the sodium ion removal rate of sodium carboxymethyl cellulose is fully considered, the acid concentration in the acidification process is strictly controlled, ammoniation is carried out under suitable temperature and pressure by using ammonia gas, and then drying and removal of uncombined ammonia gas are carried out, so that the softness and physical properties of the product paper or non-woven fabric are finally ensured.

[0035] The application can effectively restore the excellent water absorption and water retention of the fiber while ensuring the smooth progress of the reaction; in the subsequent drying process, on the one hand, the excess ammonia water can be directly volatilized, and on the other hand, the ammonia water can take away part of the water while volatilizing, which can effectively and quickly dehydrate and improve the drying efficiency. In addition, the raw material has relatively high biodegradability, and no sodium ions are added in the system, so that the obtained carboxymethyl cellulose ammonium water absorption material also has excellent biodegradability and biocompatibility.

[0036] Compared with the preparation method of carboxymethyl cellulose sodium fiber in the prior art, the preparation method of the modified fiber fabric of the application can maintain the smooth progress of the reaction, eliminate the residues of uncombined non-volatile sodium ions and potassium ions, significantly improve the preparation efficiency and product purity of the carboxymethyl cellulose ammonium water absorption material, and obtain a carboxymethyl cellulose ammonium water absorption material with excellent water absorption, water retention and biodegradability, which can be well applied in the fields of industry, agriculture, forestry and the like.

[0037] (2) The modified fiber fabric of the application has a wide range of applications, abundant raw material sources and good market prospects.

[0038] (3) The preparation method of the modified fiber fabric of the application uses the technology of “tabletting-ammoniation with ammonia gas-drying” or “drying-ammoniation with ammonia gas needling-drying”, and compared with sodium hydroxide and potassium hydroxide, sodium hydroxide and potassium hydroxide are prepared into a water / alcohol solution, which can dissolve the dried water-washed fiber, and it is difficult to make a sheet material.

[0039] If the CMC-H fiber is first made into a primary sheet and immersed in the solution to generate CMC-Na or CMC-K, although the obtained material can also achieve high water absorption after drying, the Na and K not combined with cellulose-COOH will remain on the fiber, resulting in hardening of the fiber or reduction of biocompatibility. In the application, volatile NH3 is used as the cation combined with-COOH, and the NH3 not generating CMC-NH4 will also remain on the fiber, but due to the volatility of NH3, it can be removed during drying, so that the product water absorption material has good biocompatibility and can be well applied in the fields of health care and medical treatment. BRIEF DESCRIPTION OF DRAWINGS

[0040] Fig. 1 is a photograph of the modified carboxymethyl cellulose ammonium fiber fabric (cloth) prepared in Example 1 of the application. DETAILED DESCRIPTION

[0041] The technical solutions in the embodiments of the application will be described clearly and completely in combination with the drawings in the embodiments of the application. Obviously, the described embodiments are only part of the embodiments of the application, not all the embodiments.

[0042] Fiber raw material (cellulose fiber): both natural cellulose fiber and regenerated cellulose fiber can be used in the present application, and commercially available products of bamboo fiber, cotton fiber, viscose fiber and Tencel are selected as representatives;

[0043] Common fiber: one or more of bamboo fiber, cotton fiber, wood fiber, hemp fiber, regenerated cellulose fiber, polylactic acid fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester, acrylic fiber, polypropylene fiber and ES fiber is mainly used in the present application, and bamboo fiber and polyester are taken as representatives;

[0044] Alkali agent: including sodium hydroxide, potassium hydroxide, etc., and only sodium hydroxide is taken as an example in the present application, and commercially available product of sodium hydroxide with CAS number 1310-73-2 is used;

[0045] Etherifying agent: including chloroacetic acid, sodium chloroacetate, propylene oxide, etc., and only chloroacetic acid is taken as an example in the present application, and commercially available product of chloroacetic acid with CAS number 79-11-8 is used;

[0046] Alcohol: commercially available products of methanol, ethanol and isopropanol are selected as representatives in the present application;

[0047] Acid: commercially available products of acetic acid, citric acid, hydrochloric acid and nitric acid are selected as representatives in the present application;

[0048] Ammonia: self-made.

[0049] The present application is further described in detail in combination with the drawings, examples and comparative examples. Examples

[0050] The method for preparing the modified fiber fabric comprises the following steps:

[0051] Raw material treatment: 10 kg of absolutely dry bamboo chips are cut into pieces with a length of 30-40 cm and a width of 2-3 cm, soaked in distilled water for 12 h, and then put into a digester, and pulp is prepared by sulfate process, and the cooking process is as follows: alkali amount 20% (calculated by NaOH), sulfidity 20% (calculated by Na2S), solid-liquid ratio 1:4, gradually heated to 170℃ for 2 h, and then continue to heat for 2 h, and after the cooking is completed, the prepared bamboo pulp is washed with distilled water, filtered by a flat screen with a screen gap of 0.15 mm, dried after removing impurities, and bamboo fiber is obtained;

[0052] Preparation of CMC-H: Take 1 kg of bamboo fiber, alkali and ether are carried out under the premise of maintaining the fiber morphology of the fiber, that is, first add 30 wt% sodium hydroxide solution and react, alkali at 65 ℃ for 1 h, and obtain alkali cellulose fiber; Then 0.8 kg of etherification liquid is added to the alkali cellulose fiber for etherification, and the etherification liquid contains 45 wt% chloroacetic acid, 35 wt% ethanol and 20 wt% distilled water, and is etherified at 65 ℃ for 2.5 h to obtain etherified cellulose;

[0053] Then add acid liquid and mix evenly, wherein the acid liquid is composed of 35% acetic acid and 65% pure water by volume percentage, the amount of acid liquid added is 100 kg, and the acid liquid is added twice, 50 kg each time. After adding the acid liquid for the first time, stir and acidify for 0.5 h, drain and then add the second acid liquid, continue to stir and acidify for 0.5 h after adding the acid liquid, and obtain carboxymethyl cellulose CMC-H;

[0054] Water washing: the CMC-H is washed with pure water until the pH of the residual liquid is ≥4, and the washed fiber is obtained;

[0055] Papermaking: the washed fiber is put into a water dispersion liquid and stirred to disperse evenly, and 1.0 wt% of the dispersion system is used for papermaking, the papermaking thickness is 15 g / m 2 , and a primary sheet is obtained;

[0056] Ammoniation: the primary sheet is rolled into a cloth roll with a diameter of 15 cm, placed in a sealed container, and ammonia gas is introduced at a temperature of 25±5 ℃, and the pressure is adjusted to 200-300 kPa for ammoniation, and the reaction time is 2 h;

[0057] Drying and removing uncombined ammonia gas: the ammoniated primary sheet is placed in an oven at 65 ℃ and heated for 6 min, and the moisture content is 10%, and the ammoniated fiber sheet, carboxymethyl cellulose ammonium water absorbing material, is obtained. The physical photograph is shown in FIG. 1. Example

[0058] The method for preparing the modified fiber fabric comprises the following steps:

[0059] Preparation of CMC-H: Take 1 kg of commercially available viscose fiber, the fiber length is 3.8 cm, and the fiber is alkalized and etherified under the premise of maintaining the fiber form, that is, first add 27 wt% sodium hydroxide solution and react, alkalize at 65°C for 0.8 h, and obtain alkalized cellulose fiber; then add 0.8 kg of etherification liquid to the alkalized cellulose fiber for etherification, the specific composition of the etherification liquid is chloroacetic acid 45 wt%, ethanol 35 wt% and distilled water 20 wt%, and the etherification is carried out at 65°C for 2.0 h to obtain etherified cellulose; then add acid liquid and mix uniformly, wherein the acid liquid is composed of 30% citric acid and 70% pure water by volume percentage, the amount of acid liquid added is 100 kg, the acid liquid is added twice, 50 kg each time, after adding the acid liquid for the first time, stir and acidize for 0.5 h, drain, and then add the second acid liquid, continue to stir and acidize for 0.5 h after adding the acid liquid, and obtain CMC-H;

[0060] Water washing: the CMC-H is washed with pure water until the pH of the washing residual liquid is greater than or equal to 4, and washed fiber is obtained;

[0061] Non-woven: the carded washed fiber is directly laid or cross-laid, high-pressure water is used to pierce the fiber web, the fibers are entangled into cloth, and after drying, a 45g / m 2 Spunlace cloth initial sheet;

[0062] Ammoniation: the initial sheet is wound into a cloth roll with a diameter of 10 cm, placed in a sealed container, and ammonia gas is introduced at a temperature of 65±5°C, the pressure is adjusted to 600-700 kPa for ammoniation, and the reaction time is 45 min;

[0063] Drying and removing uncombined ammonia gas: the ammoniated initial sheet is placed in a drying tunnel at 65°C and heated for 6 min, until the moisture content is 15%, and the ammoniated fiber sheet, carboxymethyl cellulose ammonium water absorption material, is obtained. Example

[0064] A method for preparing a modified fiber fabric, comprising the following steps:

[0065] Preparation of CMC-H: Take 1 kg of commercially available cotton fiber with a fiber length of 0.3-1.5 cm. Under the premise of maintaining the fiber morphology, perform alkalization and etherification. First, add it to a 27 wt% sodium hydroxide solution and react. Alkalize at 65℃ for 0.8 h to obtain alkalized cellulose fiber. Then, add 0.8 kg of etherification solution to the alkalized cellulose fiber for etherification. The specific composition of the etherification solution is 45 wt% chloroacetic acid, 35 wt% ethanol and 20 wt% distilled water. Etherify at 65℃ for 2.0 h to obtain etherified cellulose. Subsequently, add acid solution and mix evenly. The acid solution consists of 60% acetic acid and 40% purified water by volume percentage. The amount of acid solution added is 100 kg, added in two batches of 50 kg each time. After the first addition of acid solution, stir and acidify for 0.5 h before adding the second batch of acid solution. Continue stirring and acidifying for 0.5 h after the second addition of acid solution to obtain CMC-H.

[0066] Washing: CMC-H is washed with pure water until the pH of the residual washing liquid is ≥4 to obtain washed fibers;

[0067] Papermaking: Washed fibers are added to an aqueous dispersion and stirred until evenly dispersed. 1.5 wt% of the total weight of the dispersion system is used for papermaking, resulting in a paper thickness of 30 g / m². 2 A preliminary film was produced;

[0068] Ammoniation: The initial sheet is rolled into a 12cm diameter roll and placed in a sealed container. Ammonia gas is introduced at a temperature of 125±5℃ and the pressure is adjusted to 1400-1500kPa for ammoniation. The reaction time is 30min.

[0069] Drying and removal of unbound ammonia: The ammonified initial sheet is placed in a drying tunnel at 65°C and dried for 6 minutes until the moisture content is 12%, thus obtaining the ammonified fiber sheet - carboxymethyl cellulose ammonium water-absorbing material. Example

[0070] A method for preparing modified fiber fabrics includes the following steps:

[0071] Preparation of CMC-H: Take 1 kg of commercially available Tencel fiber, with a single fiber fineness of 3.0 dtex and a fiber length of 0.5-0.8 cm, and perform alkalization and etherification under the premise of maintaining the fiber morphology, that is, first add a 28 wt% sodium hydroxide solution for reaction, and perform alkalization at 65°C for 1.2 h to obtain alkalized cellulose fiber; then add 0.7 kg of etherification liquid to the alkalized cellulose fiber for etherification, and the etherification liquid has a specific composition of 45 wt% chloroacetic acid, 35 wt% ethanol, and 20 wt% distilled water, and the etherification is performed at 65°C for 1.2 h to obtain etherified cellulose; then add an acid liquid and mix uniformly, wherein the acid liquid is composed of 37% acetic acid, 3% hydrochloric acid, and 60% pure water in terms of volume percentage, and the amount of the acid liquid added is 100 kg, the acid liquid is added in two times, 50 kg each time, the acid liquid is added for the first time, and after stirring for 0.5 h, the second time of acid liquid is supplemented, and after the acid liquid is supplemented, the stirring is continued for 0.5 h to obtain CMC-H;

[0072] Water washing: the CMC-H is washed with pure water until the pH of the washing residual liquid is ≥4 to obtain washed fiber;

[0073] Papermaking: the washed fiber is put into a water dispersion liquid and stirred to disperse uniformly, and 1.2 wt% of the dispersion system is used for papermaking, with a papermaking thickness of 20 g / m 2 , to obtain a primary sheet;

[0074] Ammoniation: the primary sheet is rolled into a cloth roll with a diameter of 15 cm, placed in a sealed container, and subjected to ammoniation under the condition of a temperature of 25±5°C and an ammonia gas pressure of 200-300 kPa, with a reaction time of 2 h;

[0075] Drying and removal of unbound ammonia gas: the primary sheet after ammoniation is placed in an oven at 65°C for heating and drying for 6 min, until the moisture content is 11%, to obtain an ammoniated fiber sheet, that is, a carboxymethyl cellulose ammonium water absorption material.

[0076] Examples 5-6

[0077] Examples 5 and 6 are based on the method of Example 1, except that the acidification concentration in the preparation of CMC-H step is adjusted. In Example 5, the acetic acid concentration is lowered to 28%, and the pure water ratio is increased to 72%; in Example 6, the acetic acid concentration is lowered to 16%, and the pure water ratio is increased to 84%. Example

[0078] Example 7 is based on the method of Example 1, except that the acidification time in the preparation of CMC-H step is adjusted. In Example 7, the acidification time is 0.4 h.

[0079] Examples 8-9

[0080] Examples 8-9 are based on the method of Example 1, except that the ammonia gas is replaced with an ammonia solution soak. In Example 8, the ammonia solution is 33% ammonia water. In Example 9, the ammonia solution is 10% aqueous ammonium chloride.

[0081] Examples 10-11

[0082] Examples 10-11 are based on the method of Example 1, except that the washed fibers are dispersed in a dispersion of ordinary fibers and water. In Example 10, the ordinary fibers are wood fibers prepared from the raw materials described above. In Example 11, the ordinary fibers are hemp fibers prepared from the raw materials described above. The weight ratio of washed fibers to ordinary fibers is 50:50, and the total weight of washed fibers and ordinary fibers is 1.0 wt% of the dispersion. The paper is formed to a thickness of 15 g / m 2 to obtain a primary sheet.

[0083] Examples 12-13

[0084] Examples 12-13 are based on the method of Example 2, except that the washed fibers are mixed with ordinary fibers in a 50:50 ratio and carded. In Example 12, the ordinary fibers are regenerated cellulose fibers prepared from the raw materials described above. In Example 13, the ordinary fibers are ES fibers prepared from the raw materials described above. The carded fibers are laid flat or cross-lapped, and the fiber web is needled with high pressure water to entangle the fibers into a cloth. The cloth is dried to form a 45 g / m 2 spunlaced cloth primary sheet.

[0085] Comparative Example 1

[0086] A method of making a modified fiber fabric includes the steps of:

[0087] Take 1 kg of bamboo fiber powder through 60 mesh screen for alkalization and etherification, that is, first add 30 wt% sodium hydroxide solution for reaction, alkalization at 65℃ for 1h, obtain alkalized cellulose fiber; then add 0.8 kg of etherification liquid to the alkalized cellulose fiber for etherification, the etherification liquid contains 45 wt% acetic acid and 55 wt% distilled water, etherification at 65℃ for 2.5h, obtain etherified cellulose; then add acid liquid uniformly, wherein the acid liquid is composed of 35% acetic acid, 30% ethanol and 35% pure water by volume percentage, the amount of acid liquid added is 100 kg, the acid liquid is added twice, 50 kg each time, the second time of acid liquid is added after stirring for 0.5h after the first time of acid liquid is added, continue to stir for 0.5h after the second time of acid liquid is added. During the acidification process, the bamboo fiber powder is difficult to maintain the fiber form and is dissolved, so that the subsequent washing, papermaking, ammoniation and drying processes cannot be carried out. Therefore, it can be seen that the modified fiber fabric carboxymethyl cellulose ammonium water absorption material of the present application needs to be prepared based on the fiber form raw material.

[0088] Performance test

[0089] The water absorption materials prepared in Examples 1-13 and Comparative Example 1 were subjected to the following performance tests, and the blank group was the raw viscose fiber of Example 2, and the test results are shown in Table 2.

[0090] 1, degree of substitution

[0091] The degree of substitution of the etherified cellulose in Examples 1-13 was determined according to GB 1886.232-2016.

[0092] 2, water absorption and water retention

[0093] The water absorption materials prepared in Examples 1-17 were cut into samples to be tested with a diameter of 10 cm, the mass m1(g) of the sample before soaking was first measured, then the sample was soaked in deionized water, after 12h, the sample was taken out and drained thoroughly, then the mass m2(g) of the sample was measured, then the sample fully absorbing water was placed in an oven at 65℃, and the drying time (h) required for the weight of the sample to recover to m1(g) was recorded, and the water absorption rate of the water absorption material was calculated simultaneously = [(m2-m1) / m1]*100%, wherein the higher the water absorption rate, the better the water absorption, and the longer the drying time, the better the water retention.

[0094] 3, fiber mechanical strength and flexibility

[0095] The dry breaking strength, wet breaking strength and breaking elongation of the fiber raw material in the water absorption material were determined according to GB / T14337-2022, and the greater the dry breaking strength, wet breaking strength and breaking elongation, the better, wherein the dry breaking strength and wet breaking strength represent the mechanical strength, and the breaking elongation represents the flexibility.

[0096] 4. Sheet tensile strength test

[0097] According to GB / T 12914-2008, the test sheet is cut into 100mmx100mm, unit m / N.

[0098] 5. Determination of nonwoven sheet breaking strength

[0099] According to the textile standard FZ / T 60005 method test.

[0100] 6. Determination method of -CH2COONH4 content

[0101] The w(-CH2COONH4) content is calculated according to the following formula, that is,

[0102] w(-CH2COONH4)=N%*76 / 14*100%, wherein N% is the nitrogen content in the carboxymethyl cellulose ammonium product determined by an elemental analyzer or the Kjeldahl method or the Kjeldahl method.

[0103] Table 2 Performance test table of examples 1-13 and comparative example 1

[0104] Degree of substitution Water absorption rate / % w(-CH2COONH4) Fiber dry breaking strength / cN / dtex Fiber wet breaking strength / cN / dtex Fiber breaking elongation / % Sheet tensile strength N / m Nonwoven sheet breaking strength N Example 10.4017615.83% / / / 230 / Example 20.3320113.43%2.1 / 22 / 165 Example 30.5517020.57% / / / 310 / Example 40.222179.37%4.971.9018 / 115 Example 5 / / / / / / / / Example 6 / / / / / / / / Example 70.4011915.83% / / / 90 / Example 8 / / / / / / / / Example 9 / / / / / / / / Example 10 / 67 / / / / 260 / Example 11 / 77 / / / / 330 / Example 12 / 114 / / / / / 209 Example 13 / 121 / / / / / 480 Comparative example 1 / / / / / / / / Blank group / 7 / 2.11.423 / 165

[0105] According to table 2, it can be obtained that: in example 1, the raw material is cellulose original bamboo cellulose, after the method process of the present application is implemented, the degree of substitution of the obtained modified fiber fabric carboxymethyl cellulose ammonium water absorption material product is 0.4, the water absorption rate is 176 times of its own weight, and the water absorption performance is excellent; the sheet tensile strength is 230N / m, and the fiber still maintains excellent physical properties after treatment.

[0106] Example 2, the raw material is viscose fiber of regenerated cellulose fiber, after the process of the method of the application is implemented, the product obtained has a degree of substitution of 0.33, due to the factor of the new structure of the regenerated cellulose fiber skin, the degree of substitution is slightly lower than that of Example 1; the water absorption rate is 201 times of its own weight, the water absorption performance is excellent; the dry breaking strength of the fiber is 2.1 cN / dtex, and the fiber breaking elongation is 22%, compared with the blank group, the dry breaking strength of the fiber after treatment is not significantly decreased, which indicates that the raw material fiber has not been degraded during the preparation process of the application. The breaking strength of the non-woven piece is 165 N, and the strength of the non-woven fabric is good.

[0107] Example 3, the raw material is cotton fiber, after the process of the method of the application is implemented, the product obtained has a degree of substitution of 0.55; the water absorption rate is 170 times of its own weight, the water absorption performance is excellent; the tensile strength of the sheet is 310 N / m, and the excellent physical properties of the fiber raw material are still maintained.

[0108] Example 4, the raw material is Tencel fiber of regenerated cellulose fiber, after the process of the method of the application is implemented, the product obtained has a degree of substitution of 0.22, due to the factor of the new structure of the regenerated cellulose fiber skin, the degree of substitution is slightly lower than that of Example 1; the water absorption rate is 217 times of its own weight, the water absorption performance is excellent. The dry breaking strength of the fiber is 4.97 cN / dtex, and the fiber breaking elongation is 18%, compared with viscose fiber, Tencel fiber has more excellent physical properties of the raw material fiber, the wet breaking strength of the fiber is 1.9 cN / dtex. The breaking strength of the non-woven piece is 115 N, because the surface of Tencel fiber is smooth, the breaking strength of the cloth is lower than that of viscose fiber cloth.

[0109] From the above, the performance test results of the carboxymethyl cellulose ammonium water-absorbing material prepared by the above embodiment 1-embodiment 4 of the present application can be obtained, the modified fiber fabric prepared by the method for preparing the modified fiber fabric of the present application, the obtained modified fiber fabric carboxymethyl cellulose ammonium water-absorbing material has little influence on the original physical properties of the original fiber, and on the basis of maintaining the excellent physical properties of the raw fiber, at the same time, due to the special groups brought by the carboxymethyl cellulose ammonium, it has excellent received water absorption, water retention and biodegradability, and due to its own structure without potential cytotoxicity, it has excellent biocompatibility, and can be well applied in the fields of health care, medical treatment, industry, agriculture and forestry and the like. The relationship between the water absorption rate of the carboxymethyl cellulose ammonium water-absorbing material prepared by the present application and the -COONH4 is that, through the process implementation of the present application, the cellulose has three groups at C2, C3 and C6, that is, -OH, -COOH and -COONH4. First, from the perspective of the interaction between water molecules and hydrophilic groups, similar dissolves similar, according to the degree of polarity of the groups, the order of the interaction with water molecules from strong to weak is -COONH4, -COOH and OH. Therefore, -COONH4 has better hydrophilicity, and the water absorption performance of the -COONH4 group is significantly better than that of the -COOH and -OH groups.

[0110] On the other hand, the -COONH4 group is an ionic group, which will ionize into -COO- and NH4 + ions in the aqueous solution. -COO- is fixed on the cellulose chain, while NH4 + can move freely. It is just because of the existence of NH4 + ions that causes the difference in osmotic pressure. When the material contacts water, the micro cellulose fiber network bundle expands, and the ionization of NH4 + produces the difference in ion concentration inside and outside the network, thereby causing water molecules to penetrate into the network structure under the action of osmotic pressure. Therefore, the higher the content of -COONH4 group is, the more water molecules penetrate into the cellulose. -OH and -COOH do not have the phenomenon of ionic osmotic pressure, so the water absorption rate is not as good as that of -COONH4 group.

[0111] Based on the combination of water molecules and the oxygen atoms with strong electronegativity in the material to form hydrogen bonds, H shows +1 valence; N shows -3 valence, therefore, the oxygen atom in -COONH4 has stronger electronegativity than that of -OH and -COOH hydrogen. When the content of -COONH4 is high, the free water forms hydrogen bonds with O and is trapped, forming frozen water, and further forming a gel state, which has good water retention. Therefore, the end modification groups of the carbon positions C6, C2 and C3 in the carboxymethyl cellulose ammonium molecules in the carboxymethyl cellulose ammonium water-absorbing material of the present application include -CH2COONH4, the content range is limited to 4.3% to 58.9%, and -CH2COONH4 is directly connected with the glucose unit of the fiber, all of which can realize the high water absorption performance of the present application.

[0112] The preparation method of the present application uses cellulose fiber as raw material, which is suitable for natural cellulose fiber and / or regenerated cellulose fiber. The acid concentration in the acidification process is strictly controlled, and then ammoniation is carried out under the condition of "temperature of 0-130℃, pressure of 102kPa to less than the liquefied steam pressure of ammonia at the corresponding temperature". After that, drying and removal of uncombined ammonia are carried out. In this way, the cellulose is always kept in fiber form, the physical properties of the product fiber are ensured, and the softness and physical properties of the corresponding product paper or non-woven fabric are ensured. At the same time of maintaining the smooth progress of the reaction, the incorporation of organic solvents and impurities such as sodium ions and potassium ions is avoided, thereby improving the preparation efficiency and product purity of the modified fiber fabric carboxymethyl cellulose ammonium water absorption material.

[0113] As can be seen from the results of Example 5 and Example 6, when the acid concentration in the acidification method of the present application is less than 29%, the water content is too high, which causes a large amount of swelling or dissolution of the fiber during acidification. Because the fiber in Example 5 and Example 6 swells or dissolves a large amount, it cannot be detected.

[0114] As can be seen from the product performance test results in Example 7, compared with Example 1, the basic method and parameters are the same, except that the acidification time is shortened. Due to the shortening of the acidification time, the water absorption rate is reduced to 119 times the weight of itself, and the sheet tensile strength is 90N / m.

[0115] As can be seen from the product performance test results in Example 8 and Example 9, compared with Example 1, the basic method and parameters are the same, except that the ammonia solution is selected for ammoniation. Because the acidified fiber dissolves in the ammonia solution, the fiber swells or dissolves a large amount, which cannot be detected.

[0116] The preparation methods of Example 10 and Example 11 are based on the method of Example 1, except that the washed fiber is added to the ordinary fiber-water dispersion liquid for stirring and dispersion. In Example 10, wood fiber is added; in Example 11, hemp fiber is added; and the weight ratio of washed fiber to ordinary fiber is controlled to be 50:50. The water absorption rates are measured to be 67 times and 77 times the weight of itself, respectively. The sheet tensile strength is enhanced due to the addition of ordinary fiber, and is 260N / m and 330N / m, respectively.

[0117] Example 12~13 are based on the preparation method of Example 2, except that the washed fiber and ordinary fiber are mixed and carded in a ratio of 50:50 in the non-woven step. The water absorption rates are measured to be 114 times and 121 times the weight of itself, respectively. The non-woven sheet breaking strength is 209N and 480N, respectively. In Example 13, the ordinary fiber is ES fiber. Due to the performance of ES fiber, the non-woven sheet breaking strength is greatly enhanced.

[0118] Application Examples

[0119] The modified fiber fabric water-absorbing material prepared by the embodiments 1-4 of the present application has excellent water-absorbing property, water-retaining property, biodegradability, and excellent biocompatibility, and can be better applied in the fields of health care, medical treatment, industry, agriculture, forestry, etc., and can be made into water-absorbing pads, water-absorbing papers, water-absorbing strips, etc. for further application in sanitary napkins, wound dressings, face masks, etc.

[0120] The above is only an embodiment of the present application, for example, the cellulose fiber can be natural cellulose fiber such as cotton, hemp, bamboo, straw, etc., or regenerated cellulose fiber such as viscose, tencel, cuprammonium rayon, modal, etc., or a mixed fiber of the above two types of fibers; the common fiber is one or more of bamboo fiber, cotton fiber, wood fiber, hemp fiber, regenerated cellulose fiber, polylactic acid fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester, acrylic, polypropylene and ES fiber; the acid is one or more of acetic acid, citric acid, hydrochloric acid, nitric acid and formic acid, which has biocompatibility. The water-washed fiber of the present application can be prepared into pure carboxymethyl cellulose ammonium fiber sheet according to the need, or can be prepared into a composite fiber sheet together with other common fibers, and both can realize the modified fiber fabric and the preparation method thereof of the present application.

[0121] The above is only a preferred specific embodiment of the present application, but the protection scope of the present application is not limited thereto, any person skilled in the art can make equivalent replacement or change according to the technical solution and the inventive concept of the present application within the technical range disclosed by the present application, which should be covered within the protection scope of the present application.

Claims

1. A modified fibrous fabric characterized in that, The fiber fabric raw material is based on maintaining its fibrous shape, and is successively modified into carboxymethyl cellulose and ammonium treatment to obtain a fiber fabric with carboxymethyl cellulose ammonium as the modified product; The fiber fabric raw material is subjected to a fibrous modification treatment reaction. Specifically, during the modification treatment reaction, the 1,4-glycosidic bonds (i.e., the connection between C1 and C4) in the glucose molecules of the fiber fabric raw material are connected and the parallel cellulose chains are not changed. The specific chemical groups occupying specific carbon positions C6, C2, and C3 on the fiber molecular chains are modified.

2. A modified fibrous fabric according to claim 1, characterized in that The degree of substitution in the carboxymethyl cellulose ammonium fiber fabric after ammonia ammoniation treatment is 0.2-3.

0. The terminal modification groups of specific chemical groups at carbon positions C6, C2, and C3 in the carboxymethyl cellulose ammonium molecule include -CH2COONH4, the content of which is limited to 4.3%-58.9%. Furthermore, -CH2COONH4 is directly connected to the glucose unit of the fiber. The tensile strength of the fiber in the carboxymethyl cellulose ammonium fiber fabric is not less than 60% of the tensile strength of the fiber in the fiber fabric raw material.

3. A modified fibrous fabric according to claim 2, wherein, The raw material for the fiber fabric is cellulose fiber, which is natural cellulose fiber and / or regenerated cellulose fiber; the length of the cellulose fiber is not less than 0.5 mm.

4. A modified fibrous fabric according to claim 1 or claim 3, wherein, In the process of modifying carboxymethyl cellulose, based on maintaining the fibrous shape of cellulose fibers, alkalization and etherification are carried out in sequence, followed by the addition of acid solution and mixing evenly. The volume percentage concentration of acid in the acid solution is ≥29%. After acidification reaction, the modified product is carboxymethyl cellulose CMC-H.

5. A method for producing a modified fiber fabric, characterized by, The fiber fabric raw material is based on maintaining its fibrous shape, and is successively modified into carboxymethyl cellulose and ammonium treatment to obtain a fiber fabric with carboxymethyl cellulose ammonium as the modified product; The fiber fabric raw material is subjected to a fibrous modification treatment reaction. Specifically, during the modification treatment reaction, the 1,4-glycosidic bonds (i.e., the connection between C1 and C4) in the glucose molecules of the fiber fabric raw material are connected and the parallel cellulose chains are not changed. The specific chemical groups occupying specific carbon positions C6, C2, and C3 on the fiber molecular chains are modified.

6. A method of making a modified fibrous fabric according to claim 5, characterized in that, The raw material for the fiber fabric is cellulose fiber, and the length of the cellulose fiber is not less than 0.5 mm; In the process of modifying carboxymethyl cellulose, alkalization and etherification are carried out sequentially while maintaining the fibrous structure, followed by the addition of acid solution and uniform mixing; the volume percentage concentration of acid in the acid solution is ≥29%, and the modified product obtained after the acidification reaction is carboxymethyl cellulose CMC-H; After washing, washed fibers are obtained; The obtained washed fibers are then ammonified with ammonia to obtain fiber fabrics with carboxymethyl cellulose ammonium as the modified product. The degree of substitution of the carboxymethyl cellulose ammonium fiber fabric is 0.2-3.0, the end modification group of the specific chemical group at the carbon position C6, C2, C3 in the carboxymethyl cellulose ammonium molecule includes -CH2COONH4, the content range is limited to 4.3%-58.9%, and -CH2COONH4 is directly connected with the glucose unit of the fiber, and the breaking strength of the fiber in the carboxymethyl cellulose ammonium fiber fabric is not less than 60% of the breaking strength of the fiber in the raw material of the fiber fabric.

7. A method of making a modified fibrous fabric according to claim 6, characterized in that, After the water washing to the pH of the water washing residual liquid is greater than or equal to 4.0, the water washing fiber is obtained.

8. The method of claim 6, wherein the modified fiber fabric is prepared by a process comprising: The post-treatment drying step in the ammonia treatment step with ammonia is heating drying, the heated and dried fiber fabric after ammoniation, the obtained heat synchronously removes the uncombined ammonia in the reaction, and the heating drying is to the carboxymethyl cellulose ammonium fiber fabric with a water content of less than or equal to 15%.

9. The method for preparing a modified fiber fabric according to claim 6, characterized in that, In the ammonia treatment step with ammonia, the step of first making a sheet and then ammoniating is adopted, specifically: First, the washed fiber is made into a primary sheet by papermaking or non-woven process, and then the primary sheet is ammoniated with ammonia to obtain an ammoniated fiber sheet.

10. The method of claim 9, wherein the modified fiber fabric is prepared by a process comprising: In the process of making the washed fiber into a primary sheet, When papermaking is adopted, in the step of papermaking, the washed fiber is first uniformly dispersed in pure water or a dispersion liquid of ordinary fiber-water, and then papermaking is carried out, and the weight ratio of the washed fiber to the ordinary fiber is 10-100:90-0; When non-woven process is adopted, in the step of non-woven, the washed fiber is first uniformly mixed with ordinary fiber, and then non-woven is carried out, and the weight ratio of the washed fiber to the ordinary fiber is 10-100:90-0.

11. A method of making a modified fibrous fabric according to claim 10, characterized in that, The ordinary fiber is one or more of bamboo fiber, cotton fiber, wood fiber, hemp fiber, regenerated cellulose fiber, polylactic acid fiber, polyvinyl alcohol fiber, polyethylene fiber, polyamide fiber, polyester, acrylic, polypropylene and ES fiber.

12. The method of claim 8, wherein the modified fiber fabric is prepared by a process comprising: In the ammonia treatment step with ammonia, the step of first ammoniating and then making a sheet is adopted, specifically: First, the washed fiber is preliminarily dried, then ammoniated with ammonia to generate CMC-NH4 fiber, then heated to remove uncombined ammonia, and then the obtained fiber dry material is uniformly laid and needled to obtain an ammoniated fiber sheet.

13. The method of claim 6, wherein the modified fiber fabric is prepared by a process comprising: The acid is a biocompatible acid, and the specific acid is one or more of acetic acid, citric acid, hydrochloric acid, nitric acid and formic acid.

14. The method of claim 6, wherein the modified fiber fabric is prepared by a process comprising: The acidification is a plurality of acidification operations, and the total acidification time is 0.8h-1.5h.

15. The method of claim 13, wherein the modified fiber fabric is prepared by a process comprising: The acid solution further contains an alcohol with a volume percentage concentration of 0-50%; the alcohol is one or more of methanol, ethanol and isopropanol.

16. The method of claim 6, wherein the modified fiber fabric is prepared by the steps of: The ammonia is obtained by evaporating liquid ammonia, ammonia water or ammonia-alcohol water at a temperature of 0-130℃ and a pressure of 102kPa to a pressure lower than the liquefied vapor pressure of ammonia at the corresponding temperature.

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