Citric acid-containing acidic membrane cloth and preparation method thereof

Abstract

The invention discloses citric acid-containing acidic film cloth and a preparation method thereof, belongs to the technical field of film cloth processing, and aims to solve the technical problem that moisture absorption, antibacterial performance and degradability of mask base cloth in the prior art need to be further improved. The preparation method comprises the following steps: stirring and mixing polyethylene glycol, 2-allyl-1, 3-propylene glycol, 5-butyltetrahydro-1, 3-bis (hydroxymethyl)-1, 3, 5-triazine-2 (1H)-ketone, a catalyst and N, N-dimethylformamide, raising the temperature of a reaction system to 80-90 DEG C, and adding isophorone diisocyanate into the reaction system. After the base cloth is prepared by mixing and spunlacing the polyurethane composite fibers containing the quaternary ammonium salt cellulose and the polylactic acid fibers, the base cloth is modified by the gelatin and the citric acid, so that the moisture absorption and the dimensional stability of the acidic base cloth are effectively enhanced, and the antibacterial property and the biodegradability of the acidic base cloth are also improved.

Description

Technical Field

[0001] The present invention relates to the technical field of membrane cloth processing, and in particular to an acidic membrane cloth containing citric acid and a preparation method thereof. Background Art

[0002] Facial masks are a category of skin care products that are used to hydrate the skin. They also have multiple functions such as moisturizing, nourishing, improving appearance, and deep cleansing. The facial mask base fabrics currently supplied on the market are mainly non-woven fabrics, including traditional non-woven fabrics, fruit fibers, silk, pure cotton fibers, chitosan, etc. The surface of human skin is weakly acidic, and traditional base fabrics are usually neutral materials. They need to rely on the free acid in the essence for pH adjustment. Free acid directly contacts the skin and can easily cause burning and peeling. The applicability rate for sensitive skin is less than 30%.

[0003] In the existing technology, non-woven fabrics have the advantages of softness and high cost performance, and are widely used in facial mask base fabrics. However, the existing base fabrics cannot inhibit the growth of microorganisms in the essence, and additional preservatives such as phenoxyethanol need to be added, which can easily cause irritation reactions in sensitive skin. In addition, the existing facial mask base fabrics have a low liquid carrying capacity and are easy to absorb skin moisture, resulting in the "drier the more you apply" phenomenon. Citric acid, as a natural α-hydroxy acid, has the functions of mild exfoliation, pH regulation and chelating metal ions. It is an ideal acidic mask fabric modifier. However, when it is directly loaded on the base fabric, due to its small molecular weight and high water solubility, it is easy to be lost during the immersion or storage process. In addition, due to the influence of hygiene and effect, facial masks are usually disposable. The biodegradability of traditional non-woven fabric materials is poor, and its large-scale use will put great pressure on the ecological environment.

[0004] In view of the technical defects in this aspect, a solution is now proposed. Summary of the Invention

[0005] The purpose of the present invention is to provide an acidic membrane cloth containing citric acid and a preparation method thereof, so as to solve the technical problem in the prior art that the moisture absorption, antibacterial properties and degradability of facial mask base cloth need to be further improved.

[0006] The purpose of the present invention can be achieved through the following technical solutions:

[0007] A method for preparing an acidic membrane cloth containing citric acid comprises the following steps:

[0008] S1. Under the protection of inert gas, polyethylene glycol, 2-allyl-1,3-propylene glycol, 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, catalyst dibutyltin dilaurate and N,N-dimethylformamide are stirred and mixed, the temperature of the reaction system is increased to 80-90° C., isophorone diisocyanate is added to the reaction system, and the reaction is kept warm for 3-5 hours. A quaternized ammonium salt cellulose solution is added to the reaction system, and the reaction is kept warm for 2-3 hours. Post-treatment is performed to obtain a composite polyurethane;

[0009] The synthetic reaction formula of composite polyurethane is:

[0010]

[0011] Where: ; .

[0012] The synthetic reaction mechanism of composite polyurethane is:

[0013] During the reaction process, the catalyst catalyzes a condensation reaction between the isocyanate groups on the isophorone diisocyanate molecules and the hydroxyl groups on the polyethylene glycol, 2-allyl-1,3-propylene glycol, and 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one molecules to form a polyurethane chain with a long straight-chain structure terminated with isocyanate. Then, the isocyanate groups on the polyurethane chain condense with the hydroxyl groups on the quaternized cellulose molecules, forming a quaternized cellulose modification on the polyurethane chain while increasing the crosslinking degree of the polyurethane chain to prepare a composite polyurethane.

[0014] S2, mixing the composite polyurethane and dimethyl sulfoxide, raising the temperature of the reaction system to 70-80° C., stirring until the system is dissolved, to obtain a polyurethane spinning solution, and wet spinning to prepare a polyurethane composite fiber;

[0015] S3, preparing a base fabric using polyurethane composite fiber and polylactic acid fiber as raw materials;

[0016] S4. Immerse the base fabric in a modifying liquid at a temperature of 60-70°C, modify the base fabric by two immersions and two rollings, transfer the immersed and rolled base fabric to an ultraviolet irradiation box, irradiate and cross-link, wash with water, and dry to obtain an acidic film fabric, wherein the modifying liquid is composed of activated gelatin, modified citric acid, photoinitiator and deionized water in a dosage ratio of 5g:1g:0.1g:60mL.

[0017] Further, in step S1, the molar ratio of the polyethylene glycol, 2-allyl-1,3-propylene glycol, 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one and isophorone diisocyanate is 9:1:2:13, the polyethylene glycol is polyethylene glycol 600, the amount ratio of the polyethylene glycol, the catalyst dibutyltin dilaurate and N,N-dimethylformamide is 10g:0.2g:50mL, the isophorone The weight ratio of ketone diisocyanate to quaternized cellulose solution is 5:3, and the quaternized cellulose solution is composed of quaternized cellulose and N,N-dimethylformamide in a weight ratio of 1:5. The post-treatment comprises: after the reaction is completed, adding deionized water to the reaction system, stirring and dispersing for 20-30 minutes, filtering, washing the filter cake with deionized water three times and then drying it, transferring the filter cake to a drying oven at a temperature of 60-70°C, and vacuum drying it to constant weight to obtain a composite polyurethane.

[0018] Furthermore, in step S2, the usage ratio of the composite polyurethane and dimethyl sulfoxide is 1g:4-5mL, and the wet spinning operation includes: adding the polyurethane spinning solution to the spinning machine, setting the spinning rate to 60-80m / min, spinning into a coagulation bath, and drying to obtain a polyurethane composite fiber with a linear density of 1.8-1.9detx, wherein the aperture of the spinning machine spinneret is 0.2mm, the draft ratio of the filament bundle to the spinneret is 1.25, and the coagulation bath is deionized water.

[0019] Furthermore, in step S3, the preparation method of the base fabric is: polyurethane composite fiber and polylactic acid fiber are mixed in a weight ratio of 5:2, and after two steps of opening, carding and laying, a base fabric blank is obtained, and the base fabric blank is transferred to the spunlace process, the spunlace pressure is set to 18-20 MPa, the base fabric blank is spunlace reinforced, rolled and dehydrated, and dried to obtain the base fabric.

[0020] Furthermore, in step S4, in the double dipping and double rolling, the first dipping time is 5 minutes, the liquid carrying rate is 50-60%, the second dipping time is 3 minutes, the liquid carrying rate is 70-80%, the temperature of the UV irradiation box is 70-80°C, the irradiation dose is 6-10Gy, the drying temperature is 70-80°C, and the photoinitiator is photoinitiator 2959.

[0021] Furthermore, the preparation method of the quaternized cellulose is as follows: hydroxypropyl methylcellulose and deionized water are mixed and stirred until the system is dissolved, sodium hydroxide and epoxypropyltrimethylammonium chloride are added to the reaction system, the temperature of the reaction system is increased to 60-70° C., the reaction is kept warm for 3-5 hours, and post-processed to obtain the quaternized cellulose.

[0022] The synthetic reaction formula of quaternary ammonium salt cellulose is:

[0023]

[0024] Where: It is the abbreviation of hydroxypropyl methylcellulose.

[0025] The synthetic reaction mechanism of quaternary ammonium salt cellulose is:

[0026] During the reaction, sodium hydroxide acts as an alkaline catalyst to catalyze the ring-opening condensation between the hydroxyl groups on the hydroxypropyl methylcellulose molecules and the epoxy groups on the glycidyltrimethylammonium chloride molecules, thereby modifying the cellulose molecules with quaternary ammonium salts to prepare quaternized cellulose.

[0027] Furthermore, the dosage ratio of the hydroxypropyl methylcellulose, deionized water, sodium hydroxide and glycidyltrimethylammonium chloride is 5g:30mL:0.5g:1g, and the post-treatment includes: after the reaction is completed, distilling off low-boiling substances under reduced pressure to obtain quaternized cellulose.

[0028] Furthermore, the preparation method of the activated gelatin is as follows: gelatin and deionized water are mixed and stirred, the temperature of the reaction system is increased to 50-60°C, and the mixture is stirred until the system is dissolved, 3-butenetriethoxysilane is added to the reaction system, and the mixture is stirred for 20-30 minutes, hydrochloric acid is added to the reaction system, and the mixture is kept warm for 60-80 minutes, and the activated gelatin is obtained by post-processing.

[0029] The synthetic reaction mechanism of activated gelatin is:

[0030] During the reaction, hydrochloric acid catalyzes the hydrolysis of the siloxane bonds on the 3-butenetriethoxysilane molecules to form silanol groups, which react with the active groups on the gelatin molecules to modify the olefin double bonds on the gelatin groups to prepare activated gelatin.

[0031] Furthermore, the amount ratio of the gelatin, deionized water, 3-butenetriethoxysilane and hydrochloric acid solution is 6g:70mL:2g:5mL, the hydrochloric acid concentration is 1-2mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is lowered to room temperature, anhydrous ethanol is added to the reaction system, stirred and dispersed for 30-50min, filtered, the filter cake is washed three times with 80vol% ethanol aqueous solution and then dried, the filter cake is transferred to a drying oven at a temperature of 55-60°C, and vacuum dried to constant weight to obtain activated gelatin.

[0032] Furthermore, the preparation method of modified citric acid is as follows: sodium citrate, deionized water and sodium hydroxide are stirred and mixed, and the system is stirred until the system is dissolved, tetrahydrofuran and epoxybutene are added to the reaction system, the temperature of the reaction system is increased to 50-60°C, and the reaction is kept warm for 4-5 hours, the temperature of the reaction system is lowered to room temperature, hydrochloric acid is added to the reaction system, the pH of the system is adjusted to 3-4, the reaction is kept warm and stirred for 2-3 hours, and post-processed to obtain modified citric acid.

[0033] The synthetic reaction formula of modified citric acid is:

[0034]

[0035] The synthetic reaction mechanism of modified citric acid is:

[0036] During the reaction, under a base-catalyzed environment, the hydroxyl groups on the sodium citrate molecule undergo ring-opening condensation with the epoxy groups on the epoxybutene molecule, modifying the olefin double bond on the sodium citrate molecule. The pH of the reaction system is then adjusted with hydrochloric acid, and the sodium carboxylate salt is converted into carboxylic acid using a strong acid to produce a weak acid, thereby preparing modified citric acid.

[0037] The mass spectrometry analysis data of modified citric acid are: m / z: 262.06887 (100.0%), 263.07222 (10.8%), 264.07311 (1.6%).

[0038] Furthermore, the amount ratio of the sodium citrate, deionized water, sodium hydroxide, tetrahydrofuran and epoxybutene is 5g:20mL:0.5g:5mL:2g, the concentration of the hydrochloric acid is 3-5mol / L, and the post-treatment includes: after the reaction is completed, the temperature of the reaction system is increased to 70-80°C, low-boiling substances are removed by distillation under reduced pressure, the temperature of the reaction system is reduced to 5-10°C, anhydrous ethanol is added to the reaction system, stirred and dispersed for 30-50 minutes, filtered, and the filtrate is transferred to a rotary evaporator with a water bath temperature of 50-60°C, and low-boiling substances are removed by distillation under reduced pressure to obtain modified citric acid.

[0039] Disclosed is an acidic membrane cloth containing citric acid, which is prepared by adopting a preparation method of an acidic membrane cloth containing citric acid.

[0040] The present invention has the following beneficial effects:

[0041] 1. The acidic membrane cloth containing citric acid provided by the present invention is prepared by reinforcing the long-chain segment of polyurethane chain with quaternized ammonium cellulose to obtain an antibacterial and degradable composite polyurethane, and then preparing polyurethane composite fibers based on the composite polyurethane. The base cloth is prepared by using the composite polyurethane fibers and polylactic acid fibers as raw materials. The polylactic acid fibers have a low moisture absorption deformation rate. During the hydroentanglement reinforcement process, the polylactic acid fibers and the polyurethane composite fibers are more tightly entangled to form a high-density network, which reduces shrinkage or expansion after wet treatment and maintains the dimensional stability of the acidic membrane cloth. The high moisture absorption and antibacterial properties of the composite polyurethane fibers can effectively enhance the moisture absorption and antibacterial properties of the base cloth. The base cloth is modified by padding and loaded with polylactic acid and gelatin to further enhance the antibacterial and degradable properties of the acidic membrane cloth, effectively alleviating the impact of large-scale use of facial masks on environmental pollution.

[0042] 2. The acidic membrane cloth containing citric acid provided by the present invention uses polyethylene glycol as a soft segment to prepare a long polyurethane chain with a high soft segment ratio, thereby enhancing its hygroscopicity and flexibility. The polyurethane chain is reinforced by quaternized cellulose. The quaternary ammonium salt has strong polarity, allowing it to bind to water molecules through hydrogen bonds, increasing the hygroscopicity of the fiber. In addition, the multiple active sites contained in the quaternized cellulose can enhance the crosslinking degree of the composite polyurethane. The elastic network of the polyurethane molecular chain gives the fiber good deformation recovery ability, enabling it to resist swelling in a humid environment and reduce dimensional changes. The butyl triazone and quaternary ammonium salt in the composite polyurethane fiber molecules both have good antibacterial properties, constructing a good synergistic antibacterial system in the polyurethane composite fiber, enhancing its antibacterial properties and reducing the sensitive muscle irritation reaction caused by it.

[0043] 3. The acidic membrane cloth containing citric acid provided by the present invention is modified by padding the base cloth with a modification solution composed of activated gelatin and modified citric acid, and then irradiated and cross-linked, so that the activated gelatin and gel molecules can be stably attached to the base cloth, while increasing the cross-linking degree between the fibers of the acidic membrane cloth, further enhancing its dimensional stability. The strong moisture absorption and moisturizing properties of the activated gelatin and the strong polarity of citric acid can effectively enhance the moisture absorption properties of the acidic membrane cloth. The hydrogen ions released by citric acid reduce the pH value on the surface of the membrane cloth and inhibit the growth of microorganisms. At the same time, the carboxyl group combines with the active center of the bacterial enzyme to interfere with metabolism, thereby further enhancing the antibacterial properties of the acidic membrane cloth. The polylactic acid fibers in the acidic membrane cloth and the polyethylene glycol and quaternary polyurethane composite fibers in the polyurethane composite fibers Core components such as ammonium salt cellulose are all degradable materials. At the same time, the butyl triazone molecules introduced into the polyurethane composite fiber contain hydrophilic groups such as ester groups and hydroxymethyl groups, which increase the hydrolysis sensitivity of the polyurethane chain segments. The introduction of quaternary ammonium salts significantly increases the hydrophilicity of polyurethane, promotes the penetration and diffusion of water molecules, provides more active sites for hydrolysis reactions, and accelerates the hydrolysis of ester bonds. The gelatin modified on the acidic membrane cloth has good biodegradability and biocompatibility. The hydrophilic groups in the gelatin molecules can increase the water absorption of the acidic membrane cloth and promote water penetration. Citric acid can regulate the system to form a slightly acidic environment in the degradation process, further accelerate the hydrolysis of ester bonds, and improve the degradability of the acidic membrane cloth. DETAILED DESCRIPTION

[0044] The technical solutions of the present invention will be clearly and completely described below in conjunction with the embodiments. Obviously, the embodiments described are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0045] In the present invention, hydroxypropyl methylcellulose is selected from Zhejiang Yicun Biotechnology Co., Ltd., CAS No. 9004-65-3, and the active ingredient content is 99%;

[0046] In the present invention, polyethylene glycol 600 is selected from Nanjing Yanheng Chemical Co., Ltd., with a CAS number of 25322-68-3 and a density of 1.27 g / cm 3 , content is 99%, molecular weight is 570-630, average molecular weight is 600;

[0047] In the present invention, 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, CAS No. 16356-33-5;

[0048] In the present invention, the polylactic acid fiber is selected from Shenzhen Guanghua Weiye Co., Ltd., 1.24g / cm 3 , linear density is 1.44dtex;

[0049] In the present invention, the gelatin is selected from Guangdong Mingcheng Biotechnology Co., Ltd., is in powder form, has a CAS number of 9000-70-8, and has an active ingredient content of 99%.

[0050] Example 1

[0051] This embodiment provides a method for preparing a polyurethane composite fiber, comprising the following steps:

[0052] Step I: Preparation of quaternary ammonium salt cellulose

[0053] Weigh: 50 g of hydroxypropyl methylcellulose and 300 mL of deionized water are added to a reaction flask and stirred until the system is dissolved. 5 g of sodium hydroxide and 10 g of glycidyltrimethylammonium chloride are added to the reaction flask. The temperature of the reaction flask is raised to 60°C and kept warm for 3 hours. The reaction flask is then vacuumed to 0.1 MPa and low-boiling substances are evaporated under reduced pressure to obtain quaternary ammonium salt cellulose.

[0054] Step II: Preparation of composite polyurethane

[0055] The quaternary ammonium salt cellulose and N,N-dimethylformamide were mixed in a weight ratio of 1:5 and stirred until the system was dissolved to obtain a quaternary ammonium salt cellulose solution for later use;

[0056] Weigh: 540 g of polyethylene glycol 600, 11.6 g of 2-allyl-1,3-propylene glycol, 45.5 g of 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, 10.8 g of catalyst dibutyltin dilaurate and 2.7 L of N,N-dimethylformamide, add them into a reaction flask protected by nitrogen and stir, the temperature of the reaction flask is raised to 80° C., 289 g of isophorone diisocyanate is added to the reaction flask, and the reaction is kept warm for 3 h. 173.4 g of quaternized ammonium salt cellulose solution is added to the reaction flask, and the reaction is kept warm for 2 h. The temperature of the reaction flask is lowered to room temperature, 5 L of deionized water is added to the reaction flask, and the mixture is stirred and dispersed for 20 min. The mixture is filtered, the filter cake is washed three times with deionized water and then dried, the filter cake is transferred to a drying oven at 60° C., and vacuum dried to constant weight to obtain a composite polyurethane.

[0057] Step III: Preparation of polyurethane composite fibers

[0058] The composite polyurethane and dimethyl sulfoxide were added into a reaction flask at a ratio of 1 g:4 mL and stirred. The temperature of the reaction flask was raised to 70°C and stirred until the system was dissolved to obtain a polyurethane spinning solution.

[0059] The polyurethane spinning solution was added to the spinning machine, a spinning machine spinneret with an aperture of 0.2 mm was selected, the spinning rate was set to 60 m / min, the draft ratio of the filament bundle to the spinneret was 1.25, and the fibers were spun into deionized water, washed, and dried to obtain a polyurethane composite fiber with a linear density of 1.8 detx.

[0060] Example 2

[0061] This embodiment provides a method for preparing a polyurethane composite fiber, comprising the following steps:

[0062] Step I: Preparation of quaternary ammonium salt cellulose

[0063] Weigh: 50 g of hydroxypropyl methylcellulose and 300 mL of deionized water are added to a reaction flask and stirred until the system is dissolved. 5 g of sodium hydroxide and 10 g of glycidyltrimethylammonium chloride are added to the reaction flask. The temperature of the reaction flask is raised to 65°C and kept warm for 4 hours. The reaction flask is then vacuumed to 0.1 MPa and low-boiling substances are evaporated under reduced pressure to obtain quaternary ammonium salt cellulose.

[0064] Step II: Preparation of composite polyurethane

[0065] The quaternary ammonium salt cellulose and N,N-dimethylformamide were mixed in a weight ratio of 1:5 and stirred until the system was dissolved to obtain a quaternary ammonium salt cellulose solution for later use;

[0066] Weigh: 540 g of polyethylene glycol 600, 11.6 g of 2-allyl-1,3-propylene glycol, 45.5 g of 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, 10.8 g of catalyst dibutyltin dilaurate and 2.7 L of N,N-dimethylformamide, add them into a reaction flask protected by nitrogen and stir, the temperature of the reaction flask is raised to 85° C., 289 g of isophorone diisocyanate is added to the reaction flask, and the reaction is kept warm for 4 h. 173.4 g of quaternized ammonium salt cellulose solution is added to the reaction flask, and the reaction is kept warm for 2.5 h. The temperature of the reaction flask is lowered to room temperature, 5 L of deionized water is added to the reaction flask, stirred and dispersed for 25 min, filtered, the filter cake is washed with deionized water three times and then dried, the filter cake is transferred to a drying oven at a temperature of 65° C., and vacuum dried to constant weight to obtain a composite polyurethane.

[0067] Step III: Preparation of polyurethane composite fibers

[0068] The composite polyurethane and dimethyl sulfoxide were added into a reaction flask at a ratio of 1 g:4.5 mL and stirred. The temperature of the reaction flask was raised to 75°C and stirred until the system was dissolved to obtain a polyurethane spinning solution.

[0069] The polyurethane spinning solution was added to the spinning machine, a spinning machine spinneret with an aperture of 0.2 mm was selected, the spinning rate was set to 70 m / min, the draft ratio of the filament bundle to the spinneret was 1.25, and the fibers were spun into deionized water, washed, and dried to obtain a polyurethane composite fiber with a linear density of 1.85 detx.

[0070] Example 3

[0071] This embodiment provides a method for preparing a polyurethane composite fiber, comprising the following steps:

[0072] Step I: Preparation of quaternary ammonium salt cellulose

[0073] Weigh: 50 g of hydroxypropyl methylcellulose and 300 mL of deionized water are added to a reaction flask and stirred until the system is dissolved. 5 g of sodium hydroxide and 10 g of glycidyltrimethylammonium chloride are added to the reaction flask. The temperature of the reaction flask is raised to 70°C and kept warm for 5 hours. The reaction flask is then vacuumed to 0.1 MPa and low-boiling substances are evaporated under reduced pressure to obtain quaternary ammonium salt cellulose.

[0074] Step II: Preparation of composite polyurethane

[0075] The quaternary ammonium salt cellulose and N,N-dimethylformamide were mixed in a weight ratio of 1:5 and stirred until the system was dissolved to obtain a quaternary ammonium salt cellulose solution for later use;

[0076] Weigh: 540 g of polyethylene glycol 600, 11.6 g of 2-allyl-1,3-propylene glycol, 45.5 g of 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, 10.8 g of catalyst dibutyltin dilaurate and 2.7 L of N,N-dimethylformamide, add them into a reaction flask protected by nitrogen and stir, the temperature of the reaction flask is raised to 90° C., 289 g of isophorone diisocyanate is added to the reaction flask, and the reaction is kept warm for 5 h. 173.4 g of quaternized ammonium salt cellulose solution is added to the reaction flask, and the reaction is kept warm for 3 h. The temperature of the reaction flask is lowered to room temperature, 5 L of deionized water is added to the reaction flask, and the mixture is stirred and dispersed for 30 min. The mixture is filtered, the filter cake is washed three times with deionized water and then dried, the filter cake is transferred to a drying oven at 70° C., and vacuum dried to constant weight to obtain a composite polyurethane.

[0077] Step III: Preparation of polyurethane composite fibers

[0078] The composite polyurethane and dimethyl sulfoxide were added into a reaction flask at a ratio of 1 g:5 mL and stirred. The temperature of the reaction flask was raised to 80°C and stirred until the system was dissolved to obtain a polyurethane spinning solution.

[0079] The polyurethane spinning solution was added to the spinning machine, a spinning machine spinneret with an aperture of 0.2 mm was selected, the spinning rate was set to 80 m / min, the draft ratio of the filament bundle to the spinneret was 1.25, and the fibers were spun into deionized water, washed, and dried to obtain a polyurethane composite fiber with a linear density of 1.9 detx.

[0080] Example 4

[0081] This embodiment provides a method for preparing an acidic membrane cloth containing citric acid, comprising the following steps:

[0082] S1. Preparation of base fabric

[0083] The polyurethane composite fiber prepared in Example 1 was mixed with the polylactic acid fiber in a weight ratio of 5:2, and after two steps of opening, carding and laying, a base fabric was obtained. The base fabric was transferred to the hydroentanglement process, the hydroentanglement pressure was set to 18 MPa, the base fabric was hydroentangled, dehydrated by rolling, and dried to obtain a base fabric with a thickness of 0.12 mm.

[0084] S2. Preparation of activated gelatin

[0085] Weigh: 60 g of gelatin and 700 mL of deionized water are added to a reaction flask and stirred. The temperature of the reaction flask is raised to 50°C and stirred until the system is dissolved. 20 g of 3-butenetriethoxysilane is added to the reaction flask and stirred for 20 minutes. 50 mL of 1 mol / L hydrochloric acid is added to the reaction system and the mixture is kept warm for 60 minutes. The temperature of the reaction flask is lowered to room temperature. 2 L of anhydrous ethanol is added to the reaction flask and stirred for 30 minutes. The filter cake is washed three times with 80 vol% ethanol aqueous solution and then dried. The filter cake is transferred to a drying oven at 55°C and vacuum dried to constant weight to obtain activated gelatin.

[0086] S3. Preparation of modified citric acid

[0087] Weigh: 50 g of sodium citrate, 200 mL of deionized water and 5 g of sodium hydroxide, add them to a reaction flask and stir until the system is dissolved, add 50 mL of tetrahydrofuran and 20 g of epoxybutene to the reaction flask, raise the temperature of the reaction flask to 50 ° C, keep the reaction for 4 hours, lower the temperature of the reaction flask to room temperature, add 3 mol / L hydrochloric acid to the reaction system, adjust the pH of the system to 3, keep the reaction warm and stir for 2 hours, raise the temperature of the reaction flask to 70 ° C, remove low boiling points under reduced pressure, lower the temperature of the reaction flask to 5 ° C, add 200 mL of anhydrous ethanol to the reaction flask, stir and disperse for 30 minutes, filter, transfer the filtrate to a rotary evaporator with a water bath temperature of 50 ° C, and remove low boiling points under reduced pressure to obtain modified citric acid.

[0088] S4. Preparation of modified liquid

[0089] Under a light-shielding environment, activated gelatin, modified citric acid, photoinitiator 2959 and deionized water were added to a reaction flask in a dosage ratio of 5 g:1 g:0.1 g:60 mL and stirred. The temperature of the reaction flask was raised to 70°C and stirred at this temperature until the system was dissolved to obtain a modified solution.

[0090] S5. Preparation of acidic membrane cloth

[0091] The base fabric was dipped and rolled in a modifying liquid at a temperature of 60°C, and the fabric was dipped and rolled twice. The first dipping time was set to 5 minutes, the rolling liquid rate was 50%, the second dipping time was set to 3 minutes, and the rolling liquid rate was 70% to obtain a dipped base fabric. The dipped base fabric was transferred to an ultraviolet irradiation box at a temperature of 70°C, and irradiated and cross-linked at an irradiation dose of 6Gy. After washing with deionized water, it was transferred to a drying box at a temperature of 70°C and dried to obtain an acidic film cloth.

[0092] Example 5

[0093] This embodiment provides a method for preparing an acidic membrane cloth containing citric acid, comprising the following steps:

[0094] S1. Preparation of base fabric

[0095] The polyurethane composite fiber prepared in Example 2 was mixed with the polylactic acid fiber in a weight ratio of 5:2, and after two steps of opening, carding and laying, a base fabric was obtained. The base fabric was transferred to the hydroentanglement process, the hydroentanglement pressure was set to 19 MPa, the base fabric was hydroentangled, dehydrated by rolling, and dried to obtain a base fabric with a thickness of 0.13 mm.

[0096] S2. Preparation of activated gelatin

[0097] Weigh: 60 g of gelatin and 700 mL of deionized water are added to a reaction flask and stirred. The temperature of the reaction flask is raised to 55°C and stirred until the system is dissolved. 20 g of 3-butenetriethoxysilane is added to the reaction flask and stirred for 25 minutes. 50 mL of 1.5 mol / L hydrochloric acid is added to the reaction system and the reaction is kept warm for 70 minutes. The temperature of the reaction flask is lowered to room temperature. 2 L of anhydrous ethanol is added to the reaction flask and stirred for 40 minutes. Filter and wash the filter cake with 80 vol% ethanol aqueous solution three times and then dry it. Transfer the filter cake to a drying oven at 57°C and vacuum dry it to constant weight to obtain activated gelatin.

[0098] S3. Preparation of modified citric acid

[0099] Weigh: 50 g of sodium citrate, 200 mL of deionized water and 5 g of sodium hydroxide, add them to a reaction flask and stir until the system is dissolved, add 50 mL of tetrahydrofuran and 20 g of epoxybutene to the reaction flask, raise the temperature of the reaction flask to 55 ° C, keep the reaction warm for 4.5 hours, lower the temperature of the reaction flask to room temperature, add 4 mol / L hydrochloric acid to the reaction system, adjust the pH of the system to 3.5, keep the reaction warm and stir for 2.5 hours, raise the temperature of the reaction flask to 75 ° C, remove low boiling points under reduced pressure, lower the temperature of the reaction flask to 8 ° C, add 200 mL of anhydrous ethanol to the reaction flask, stir and disperse for 40 minutes, filter, transfer the filtrate to a rotary evaporator with a water bath temperature of 55 ° C, and remove low boiling points under reduced pressure to obtain modified citric acid.

[0100] S4. Preparation of modified liquid

[0101] Under a light-shielding environment, activated gelatin, modified citric acid, photoinitiator 2959 and deionized water were added to a reaction flask in a dosage ratio of 5 g:1 g:0.1 g:60 mL and stirred. The temperature of the reaction flask was raised to 75°C and stirred at this temperature until the system was dissolved to obtain a modified solution.

[0102] S5. Preparation of acidic membrane cloth

[0103] The base fabric was immersed in the modifying liquid at a temperature of 65°C, immersed and rolled twice, and the first immersion time was set to 5 minutes, the rolling liquid rate was 55%, the second immersion time was set to 3 minutes, and the rolling liquid rate was 75% to obtain the immersed base fabric. The immersed base fabric was transferred to an ultraviolet irradiation box at a temperature of 75°C, and irradiated and cross-linked at an irradiation dose of 8Gy. After washing with deionized water, it was transferred to a drying box at a temperature of 75°C and dried to obtain an acidic film cloth.

[0104] Example 6

[0105] This embodiment provides a method for preparing an acidic membrane cloth containing citric acid, comprising the following steps:

[0106] S1. Preparation of base fabric

[0107] The polyurethane composite fiber prepared in Example 3 was mixed with the polylactic acid fiber in a weight ratio of 5:2, and after two steps of opening, carding and laying, a base fabric was obtained. The base fabric was transferred to the hydroentanglement process, the hydroentanglement pressure was set to 20 MPa, the base fabric was hydroentangled, dehydrated and dried to obtain a base fabric with a thickness of 0.14 mm.

[0108] S2. Preparation of activated gelatin

[0109] Weigh: 60 g of gelatin and 700 mL of deionized water are added to a reaction flask and stirred. The temperature of the reaction flask is raised to 60°C and stirred until the system is dissolved. 20 g of 3-butenetriethoxysilane is added to the reaction flask and stirred for 30 min. 50 mL of 2 mol / L hydrochloric acid is added to the reaction system and the mixture is kept warm for 80 min. The temperature of the reaction flask is lowered to room temperature. 2 L of anhydrous ethanol is added to the reaction flask and stirred for 50 min. The filter cake is washed three times with 80 vol% ethanol aqueous solution and then dried. The filter cake is transferred to a drying oven at 60°C and vacuum dried to constant weight to obtain activated gelatin.

[0110] S3. Preparation of modified citric acid

[0111] Weigh: 50 g of sodium citrate, 200 mL of deionized water and 5 g of sodium hydroxide, add them to a reaction flask and stir until the system is dissolved, add 50 mL of tetrahydrofuran and 20 g of epoxybutene to the reaction flask, raise the temperature of the reaction flask to 60 ° C, keep the reaction warm for 5 hours, lower the temperature of the reaction flask to room temperature, add 5 mol / L hydrochloric acid to the reaction system, adjust the pH of the system to 4, keep the reaction warm and stir for 3 hours, raise the temperature of the reaction flask to 80 ° C, remove low boiling points under reduced pressure, lower the temperature of the reaction flask to 10 ° C, add 200 mL of anhydrous ethanol to the reaction flask, stir and disperse for 50 minutes, filter, transfer the filtrate to a rotary evaporator with a water bath temperature of 60 ° C, and remove low boiling points under reduced pressure to obtain modified citric acid.

[0112] S4. Preparation of modified liquid

[0113] Under a light-shielding environment, activated gelatin, modified citric acid, photoinitiator 2959 and deionized water were added to a reaction flask in a dosage ratio of 5g:1g:0.1g:60mL and stirred. The temperature of the reaction flask was raised to 80°C and stirred at this temperature until the system was dissolved to obtain a modified solution.

[0114] S5. Preparation of acidic membrane cloth

[0115] The base fabric was dipped and rolled in a modifying liquid at a temperature of 70°C, and the fabric was dipped and rolled twice. The first dipping time was set to 5 minutes, the rolling liquid rate was 60%, the second dipping time was set to 3 minutes, and the rolling liquid rate was 80% to obtain a dipped base fabric. The dipped base fabric was transferred to an ultraviolet irradiation box at a temperature of 80°C, and irradiated and cross-linked at an irradiation dose of 10Gy. After washing with deionized water, it was transferred to a drying box at a temperature of 80°C and dried to obtain an acidic film cloth.

[0116] Comparative Example 1

[0117] The difference between this comparative example and Example 6 is that, when preparing the polyurethane composite fiber, step I is omitted, and the quaternized cellulose solution in step II is replaced by hydroxypropyl methylcellulose in step I.

[0118] Comparative Example 2

[0119] The difference between this comparative example and Example 6 is that when the polyurethane composite fiber is prepared, no 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one is added in step II.

[0120] Comparative Example 3

[0121] The difference between this comparative example and Example 6 is that in step S4, modified citric acid is not added.

[0122] Comparative Example 4

[0123] The difference between this comparative example and Example 6 is that step S2 is eliminated and the activated gelatin in step S4 is replaced by the gelatin in step S2.

[0124] Performance testing:

[0125] The acidic membrane cloths prepared in Examples 4-6 and Comparative Examples 1-4 were cut into 10 cm × 10 cm test samples, placed in deionized water, and kept completely immersed for 15 minutes. The test samples were fished out of the deionized water and drained vertically until no liquid dripped. According to the formula Determine the moisture absorption rate of the sample to be tested, where m1 is the weight of the sample to be tested after moisture absorption, and m0 is the weight of the sample to be tested. Determine the dimensional change rate of the test sample, where S1 is the area of the test sample after moisture absorption, and S0 is the area of the test sample;

[0126] The antibacterial properties of the acidic film cloth samples prepared in Examples 4-6 and Comparative Examples 1-4 were measured with reference to the standard GB / T 20944.3-2008 "Evaluation of antibacterial properties of textiles Part 3: Oscillation method";

[0127] The biodegradability of the acidic membrane samples prepared in Examples 4-6 and Comparative Examples 1-4 was determined over 90 days in accordance with the standard GB / T 33616-2017 “Evaluation of Biodegradability of Textile Nonwovens - Determination of Carbon Dioxide Emission”.

[0128] The specific test results are shown in Table 1 below.

[0129] Table 1-Performance test data of the sample

[0130]

[0131] Data Analysis:

[0132] A comparative analysis of the data in Table 1 above shows that the moisture absorption rate of the acidic film cloth sample prepared by the present invention reaches 1180%, the dimensional change rate after moisture absorption is reduced to 1.6%, the antibacterial performance against Staphylococcus aureus reaches 99.6%, the antibacterial performance against Escherichia coli reaches 99.6%, and the antibacterial performance against Candida albicans reaches 99.8%. Its biodegradability within 90 days reaches 78.6%. All performance test data are better than those of the comparative example, indicating that the present invention prepares a polyurethane composite fiber by reinforcing polyurethane with quaternized ammonium cellulose, and then mixes it with polylactic acid fiber for hydroentanglement to prepare a base fabric, and modifies the base fabric by gelatin and citric acid. It not only effectively enhances the moisture absorption and dimensional stability of the acidic base fabric, but also improves its antibacterial and biodegradable properties.

[0133] The above contents are merely examples and explanations of the structure of the present invention. Those skilled in the art may make various modifications or additions to the described specific embodiments or replace them in a similar manner. As long as they do not deviate from the structure of the invention or exceed the scope defined by the claims, they shall fall within the scope of protection of the present invention.

[0134] Throughout this specification, references to terms such as "one embodiment," "example," or "specific example" indicate that the specific features, structures, materials, or characteristics described in conjunction with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, schematic representations of these terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in any one or more embodiments or examples.

[0135] The preferred embodiments of the present invention disclosed above are intended only to help illustrate the present invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the present invention to specific embodiments. Obviously, many modifications and variations are possible based on the contents of this specification. These embodiments are selected and described in detail in this specification to better explain the principles and practical applications of the present invention, thereby enabling those skilled in the art to better understand and utilize the present invention. The present invention is limited only by the claims and their full scope and equivalents.

Claims

1. A method for preparing an acidic membrane cloth containing citric acid, characterized in that: The following steps are involved: S1. Under the protection of inert gas, polyethylene glycol, 2-allyl-1,3-propylene glycol, 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one, catalyst dibutyltin dilaurate and N,N-dimethylformamide are stirred and mixed, the temperature of the reaction system is increased to 80-90° C., isophorone diisocyanate is added to the reaction system, and the reaction is kept warm for 3-5 hours. A quaternized ammonium salt cellulose solution is added to the reaction system, and the reaction is kept warm for 2-3 hours. Post-treatment is performed to obtain a composite polyurethane; S2, mixing the composite polyurethane and dimethyl sulfoxide, raising the temperature of the reaction system to 70-80° C., stirring until the system is dissolved, to obtain a polyurethane spinning solution, and wet spinning to prepare a polyurethane composite fiber; S3, preparing a base fabric using polyurethane composite fiber and polylactic acid fiber as raw materials; S4. Immerse the base fabric in a modifying liquid at a temperature of 60-70°C, modify the base fabric by two immersions and two rollings, transfer the immersed and rolled base fabric to an ultraviolet irradiation box, irradiate and cross-link, wash with water, and dry to obtain an acidic film fabric, wherein the modifying liquid is composed of activated gelatin, modified citric acid, photoinitiator and deionized water in a dosage ratio of 5g:1g:0.1g:60mL.

2. The method for preparing an acidic membrane cloth containing citric acid according to claim 1, characterized in that: In step S1, the molar ratio of the polyethylene glycol, 2-allyl-1,3-propylene glycol, 5-butyltetrahydro-1,3-bis(hydroxymethyl)-1,3,5-triazine-2(1H)-one and isophorone diisocyanate is 9:1:2:13, the polyethylene glycol is polyethylene glycol 600, the amount ratio of the polyethylene glycol, the catalyst dibutyltin dilaurate and N,N-dimethylformamide is 10g:0.2g:50mL, the weight ratio of isophorone diisocyanate and the quaternized cellulose solution is 5:3, and the quaternized cellulose solution is composed of quaternized cellulose and N,N-dimethylformamide in a weight ratio of 1:5; in step S2, the amount ratio of the composite polyurethane and dimethyl sulfoxide is 1g:4-5mL.

3. The method for preparing an acidic membrane cloth containing citric acid according to claim 1, characterized in that: In step S4, in the double dipping and double rolling, the first dipping time is 5 minutes, the liquid carrying rate is 50-60%, the second dipping time is 3 minutes, the liquid carrying rate is 70-80%, the temperature of the UV irradiation box is 70-80°C, the irradiation dose is 6-10Gy, and the photoinitiator is photoinitiator 2959.

4. The method for preparing an acidic membrane cloth containing citric acid according to claim 2, characterized in that: The preparation method of the quaternary ammonium salt cellulose comprises: mixing hydroxypropyl methylcellulose and deionized water and stirring until the system is dissolved, adding sodium hydroxide and epoxypropyltrimethylammonium chloride to the reaction system, raising the temperature of the reaction system to 60-70° C., keeping the temperature for reaction for 3-5 hours, and post-treating to obtain the quaternary ammonium salt cellulose.

5. The method for preparing an acidic membrane cloth containing citric acid according to claim 4, characterized in that: The usage ratio of the hydroxypropyl methylcellulose, deionized water, sodium hydroxide and glycidyltrimethylammonium chloride is 5 g:30 mL:0.5 g:1 g.

6. The method for preparing an acidic membrane cloth containing citric acid according to claim 1, characterized in that: The preparation method of the activated gelatin comprises the following steps: mixing gelatin and deionized water, raising the temperature of the reaction system to 50-60° C., stirring until the system is dissolved, adding 3-butenetriethoxysilane to the reaction system, stirring for 20-30 minutes, adding hydrochloric acid to the reaction system, keeping the temperature for reaction for 60-80 minutes, and post-processing to obtain the activated gelatin.

7. The method for preparing an acidic membrane cloth containing citric acid according to claim 6, characterized in that: The usage ratio of the gelatin, deionized water, 3-butylenetriethoxysilane and hydrochloric acid solution is 6g:70mL:2g:5mL, and the concentration of the hydrochloric acid is 1-2mol / L.

8. The method for preparing an acidic membrane cloth containing citric acid according to claim 1, characterized in that: The preparation method of the modified citric acid is as follows: sodium citrate, deionized water and sodium hydroxide are stirred and mixed, and the system is stirred until the system is dissolved, tetrahydrofuran and epoxybutene are added to the reaction system, the temperature of the reaction system is increased to 50-60°C, and the reaction is carried out by heat preservation for 4-5 hours, the temperature of the reaction system is lowered to room temperature, hydrochloric acid is added to the reaction system, the pH of the system is adjusted to 3-4, the reaction is stirred for 2-3 hours, and post-processed to obtain the modified citric acid.

9. The method for preparing an acidic membrane cloth containing citric acid according to claim 8, characterized in that: The usage ratio of the sodium citrate, deionized water, sodium hydroxide, tetrahydrofuran and epoxybutene is 5g:20mL:0.5g:5mL:2g, and the concentration of the hydrochloric acid is 3-5mol / L.

10. An acidic membrane cloth containing citric acid, characterized in that: The acidic membrane cloth containing citric acid is prepared by the preparation method of the acidic membrane cloth containing citric acid according to any one of claims 1 to 9.

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