Dialysis paper and method for producing the same

Abstract

The application relates to the paper manufacturing technical field, in particular to dialysis paper and a preparation method thereof. The dialysis paper comprises 70-75 parts of regenerated fibers, 20-25 parts of polyolefin fibers and a reinforcing agent, wherein the basis weight of the dialysis paper is 50-85 g / m2. According to the technical scheme, the regenerated fibers with less dissolved substance are used, the safety of raw materials is ensured compared with wood pulp fibers in the prior art, the low-melting-point polyolefin fibers can be melted on the surface of the polyolefin fibers in the hot-pressing process, the surrounding fibers are adhered, and the strength of the dialysis paper is improved. The regenerated fibers have good splitting characteristics, the low-melting-point polyolefin fibers with more branches have more fiber branches, different fibers with different freenesses are selected and matched, and a reasonable paper pore structure is realized.

Description

Technical Field

[0001] This application relates to the field of paper manufacturing technology, and more specifically, to a dialysis paper and a method for preparing the same. Background Technology

[0002] With the rapid development of the medical industry and people's increasing attention to health, higher requirements have been placed on the strength, air permeability, heat sealing, and antibacterial properties of medical dialysis paper. The requirements for Class III medical devices are even more stringent, requiring not only to meet the requirements of antibacterial and air permeability, but also to pay attention to the toxicity of the dialysis paper itself to ensure the biosafety of the dialysis paper.

[0003] Chinese patent application CN118272959A discloses a dialysis paper made of synthetic fibers with a high-toughness core-sheath structure. The strength of the dialysis paper is greatly improved, but its air permeability is reduced accordingly. However, it does not address the toxicity problem of the dialysis paper itself.

[0004] Chinese patent application CN105970719A discloses a medical dialysis paper, comprising a paper base and a hot melt adhesive layer coated on the upper and lower surfaces of the paper base. The paper base contains 60-65 parts by weight of hardwood raw material, 30-35 parts by weight of softwood raw material, 7-10 parts by weight of bamboo charcoal fiber, and 3-5 parts by weight of polyester staple fiber. The hot melt adhesive layer contains 60-75 parts by weight of ethylene-vinyl acetate copolymer, 15-25 parts by weight of polyamide resin, 1-2 parts by weight of paraffin wax, 1.5-2 parts by weight of antioxidant, 5-8 parts by weight of bamboo charcoal fiber powder, 2-3 parts by weight of barium stearate, 8-15 parts by weight of hydrogenated rosin, 1-1.5 parts by weight of fluorinated graphite, and 0.2-0.4 parts by weight of phenyl phthalate. However, the strength of this medical dialysis paper is still insufficient, and its antibacterial performance is generally poor. Moreover, some of the chemicals used will dissolve during the sterilization process, exhibiting certain cytotoxicity.

[0005] Chinese patent application CN103498383A discloses a medical dialysis paper made from coniferous and broadleaf wood fibers using traditional papermaking processes. Because the broadleaf wood used in this method has high permeability and the coniferous wood has high strength, the medical dialysis paper produced has good air permeability and strength. However, this medical dialysis paper uses a large amount of wood pulp fiber, which will dissolve β-glucan during steam sterilization, affecting the detection of bacterial endotoxins.

[0006] Chinese patent application CN117328288A discloses a medical dialysis paper and its manufacturing process. The dialysis paper is prepared using viscose fiber, additives, and conventional wood pulp fiber. The strength and air permeability of the paper are improved by modifying the viscose fiber and changing the freeness of the wood pulp fiber. However, the production process uses a wet strength agent PAE (polyamide epichlorohydrin), which is harmful to the human body. Due to the hydrolysis side reaction of epichlorohydrin, organochlorine compounds are produced, mainly including 1,3-difluoro-2-propanol (DCP) and 3-chloro-1,2-propanediol. These substances can have adverse effects on the human reproductive system and are considered to be carcinogenic.

[0007] In summary, there is an urgent need in this field for a new type of dialysis paper to solve the aforementioned technical problems.

[0008] In view of the above, this application is hereby submitted. Summary of the Invention

[0009] The purpose of this application is to provide a composite idler roller and a method for preparing the same, so as to solve at least one of the technical problems mentioned in the background art.

[0010] Specifically, in a first aspect, this application provides a dialysis paper comprising:

[0011] 70-75 parts of regenerated fiber

[0012] 20-30 parts of polyolefin fiber

[0013] 5-15 parts of reinforcing agent

[0014] The basis weight of the dialysis paper is 50-85 g / m³. 2 .

[0015] By employing the above technical solution, the use of recycled fibers with fewer leachates ensures the safety of raw materials compared to existing wood pulp fibers. The use of low-melting-point polyolefin fibers allows the surface of the polyolefin fibers to melt during hot pressing, acting as an adhesive to surrounding fibers and improving the strength of the dialysis paper. Recycled fibers have good filament splitting characteristics; low-melting-point, multi-branched polyolefin fibers have more fiber branches. By selecting and combining fibers with different degrees of freeness, a reasonable paper pore structure can be achieved.

[0016] Preferably, the basis weight of the dialysis paper is 65-75 g / m³. 2 .

[0017] Preferably, the reinforcing agent content in the dialysis paper is 8-12%.

[0018] Preferably, the regenerated fiber includes at least one of seaweed fiber, lyocell fiber, chitosan fiber, and soybean protein composite fiber; the polyolefin fiber is a low-melting-point polyolefin fiber, including at least one of polyethylene fiber, polypropylene fiber, matrix-fiber type polyolefin fiber, and parallel type polyolefin fiber; the reinforcing agent includes at least one of modified xyloglucan, acrylic copolymer, and waterborne polyurethane.

[0019] Preferably, the polyolefin fiber has a thickness of 0.8-15 mg / m, a freeness of 200-600 mL, and a heat-melting temperature of 100-150℃. More preferably, the polyolefin fiber is a multi-branched polyolefin fiber. Even more preferably, the polyolefin fiber has a thickness of 3-10 mg / m, a freeness of 400-500 mL, and a heat-melting temperature of 100-135℃.

[0020] A second aspect of this application provides a method for preparing dialysis paper as described in the first aspect of this application, comprising the steps of:

[0021] The preparation steps of slurry M1 are as follows: the regenerated fibers are pulped to obtain slurry M1;

[0022] The preparation steps of slurry M2 are as follows: the polyolefin fibers are dispersed evenly to obtain slurry M2;

[0023] The preparation steps of slurry M3 are as follows: slurry M1 and slurry M2 are mixed evenly to obtain slurry M3;

[0024] In the step of obtaining semi-dry paper web, the mass concentration of pulp M3 is adjusted to 0.6-0.8%, and then dewatered, pressed, and dried to obtain semi-dry paper web;

[0025] The step of obtaining semi-finished dialysis paper involves immersing the semi-dry paper web in a reinforcing agent, removing excess reinforcing agent from the paper web, and then drying it to obtain semi-finished dialysis paper.

[0026] The step of obtaining finished dialysis paper involves hot pressing the semi-finished dialysis paper to obtain the finished dialysis paper.

[0027] Preferably, in the step of obtaining semi-dry paper web, a long-wire multi-cylinder paper machine is used to achieve dewatering, pressing, and drying.

[0028] Preferably, in the step of obtaining semi-finished dialysis paper, a two-roll extruder is used to remove excess reinforcing agent from the paper web.

[0029] Preferably, the freeness of the M1 slurry is 250-350 mL, and the coarseness is 0.2-0.35 mg / m.

[0030] Preferably, the polyolefin fiber has a thickness of 0.8-15 mg / m, a freeness of 200-600 mL, and a heat-melting temperature of 100-150℃. More preferably, the polyolefin fiber is a multi-branched polyolefin fiber. Even more preferably, the polyolefin fiber has a thickness of 3-10 mg / m, a freeness of 400-500 mL, and a heat-melting temperature of 100-135℃.

[0031] Preferably, the reinforcing agent is at least one emulsion selected from modified xylo-glucan, acrylic copolymer, and waterborne polyurethane, and the mass concentration of the emulsion is 15-20%.

[0032] Preferably, the dryness of the semi-dry paper web is 50-80%, more preferably 60-65%.

[0033] Preferably, in the step of obtaining the finished dialysis paper, the hot-pressing temperature of the semi-finished dialysis paper is 130-140℃.

[0034] Preferably, the basis weight of the finished dialysis paper is 50-85 g / m³. 2 More preferably, the basis weight of the finished dialysis paper is 65-75 g / m³. 2 .

[0035] In summary, this application has the following beneficial effects:

[0036] First, the dialysis paper provided in this application, through the proportion of components such as regenerated fiber, polyolefin fiber, and reinforcing agent, achieves better strength, breathability, antibacterial properties, lower bacterial endotoxins and toxicity, and better biosafety, thereby ensuring its reliability when used as a medical device and avoiding foreign body reactions during surgery.

[0037] Secondly, the dialysis paper provided in this application, by using recycled fibers with fewer leachables compared to wood pulp fibers in the prior art, ensures the safety of the raw materials. The use of low-melting-point polyolefin fibers allows the surface of the polyolefin fibers to melt during hot pressing, thus adhering to surrounding fibers and improving the strength of the dialysis paper. Recycled fibers have better filament splitting characteristics, and low-melting-point, multi-branched polyolefin fibers have more fiber branches. By selecting and combining fibers with different degrees of freeness, a reasonable paper pore structure can be achieved.

[0038] Third, the method for preparing dialysis paper provided in this application, by preparing M1, M2 and M3 of each component separately, and then preparing semi-dry paper webs and semi-finished dialysis paper in sequence, can make the obtained dialysis paper have better strength, air permeability and biosafety. Detailed Implementation

[0039] Exemplary embodiments will be described in detail below. The embodiments described in the following exemplary embodiments do not represent all embodiments consistent with this application. Rather, they are merely examples of apparatuses and methods consistent with some aspects of this application as detailed in the appended claims.

[0040] The terminology used in this application is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The singular forms “a,” “the,” and “the” used in this application and the appended claims are also intended to include the plural forms unless the context clearly indicates otherwise. It should also be understood that the term “and / or” as used herein refers to and includes any or all possible combinations of one or more of the associated listed items.

[0041] The present application will be described in detail below through examples.

[0042] With the rapid development of the medical industry and people's increasing attention to health, higher requirements have been placed on the strength, air permeability, heat sealing, and antibacterial properties of medical dialysis paper. As a Class III medical device, medical dialysis paper has stricter quality requirements. It not only needs to meet the requirements of antibacterial and air permeability, but also needs to pay attention to the toxicity of the dialysis paper itself to ensure the biosafety of the dialysis paper.

[0043] In view of the above, in order to solve the existing technical problems in the background art, the inventive concept of this application is to provide a dialysis paper and a method for preparing the same, wherein the dialysis paper comprises: 70-75 parts of regenerated fiber, 20-25 parts of polyolefin fiber, and 5-15 parts of reinforcing agent, wherein the basis weight of the dialysis paper is 50-85 g / m³. 2 .

[0044] According to this invention concept, by using recycled fibers with fewer leachables, the safety of raw materials is ensured compared to wood pulp fibers in existing technologies. The use of low-melting-point polyolefin fibers allows the surface of the polyolefin fibers to melt during hot pressing, acting as an adhesive to surrounding fibers and improving the strength of the dialysis paper. Recycled fibers have better filament splitting characteristics; low-melting-point, multi-branched polyolefin fibers have more fiber branches. By selecting and combining fibers with different degrees of freeness, a reasonable paper pore structure can be achieved.

[0045] Furthermore, based on the disclosure of this application, the most widely used traditional wet strength agent is polyamide epichlorohydrin (PAE). This chemical can effectively improve the wet strength of paper, but it is also harmful to human health and the environment. During its production process, epichlorohydrin undergoes a hydrolysis side reaction, producing organochlorine compounds, mainly including 1,3-difluoro-2-propanol (DCP) and 3-chloro-1,2-propanediol. These substances can adversely affect the human reproductive system and are considered carcinogenic. This application adds low-melting-point polyolefin multi-branched fibers as reinforcing fibers, thus eliminating the need for wet strength agents and eliminating the possibility of toxicity. This prevents the addition of hazardous substances from the source, ensuring the biosafety of the dialysis paper.

[0046] Furthermore, in the field of medical dialysis paper, current technologies employ sizing methods during production to achieve water resistance. The additives used are often starch, alkyl ketone dimers, or mixtures of both. These substances can leach harmful compounds during high-temperature sterilization. These compounds possess cytotoxicity and, if they adhere to medical devices, can cause hemolysis and other abnormal toxicities after surgery, increasing the risk of medical accidents. This invention uses acrylic emulsions as reinforcing agents, which not only exhibit excellent water resistance but also possess high safety due to FDA certification.

[0047] To better understand the above technical solutions, the following detailed descriptions will be provided in conjunction with specific implementation methods. Those skilled in the art should also understand that the reaction time and component feeding involved in this application cannot be absolutely precise in actual production, but are all within the allowable error range. For example, if the desired heating time is 30 minutes, the actual operation may be 30 minutes plus or minus 1 second; if the desired sample weight is 30g, the actual weight may be 30.001g or 29.998g.

[0048] Unless otherwise specified, all raw materials mentioned in this application are commercially available products.

[0049] Example 1

[0050] 75 portions of seaweed fiber were pulped to obtain pulp M1 with a freeness of 250 mL and a coarseness of 0.3 mg / m.

[0051] 25 parts of low-melting-point polyethylene fiber with a coarseness of 8 mg / m and a freeness of 400 mL were evenly dispersed to obtain slurry M2, wherein the melting point of the low-melting-point polyethylene fiber is 135℃.

[0052] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0053] The mass concentration of pulp M3 was adjusted to 0.6%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 60%.

[0054] The semi-dry paper sheet is immersed in an acrylic copolymer with a mass concentration of 15% as a reinforcing agent, and then the excess reinforcing agent is expelled from the paper web using a two-roll extruder. After drying, a semi-finished dialysis paper is obtained.

[0055] The semi-finished dialysis paper was hot-pressed at 130℃ to obtain a basis weight of 70 g / m³. 2 The finished dialysis paper was obtained; and the content of acrylic copolymer in the finished paper was measured to be 8%.

[0056] Example 2

[0057] Seventy parts of lyocell fiber were pulped to obtain pulp M1 with a freeness of 350 mL and a coarseness of 0.2 mg / m.

[0058] 30 parts of low-melting-point polyethylene fiber with a coarseness of 3 mg / m and a freeness of 500 mL were evenly dispersed to obtain slurry M2, wherein the melting point of the low-melting-point polyethylene fiber is 100℃.

[0059] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0060] The mass concentration of pulp M3 was adjusted to 0.6%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0061] The semi-dry paper sheet is immersed in an acrylic copolymer with a mass concentration of 15% as a reinforcing agent, and then the excess reinforcing agent is expelled from the paper web by a two-roll extruder and dried to obtain a semi-finished dialysis paper.

[0062] The semi-finished dialysis paper was hot-pressed at 130℃ to obtain a basis weight of 75 g / m³. 2 The finished dialysis paper was obtained; and the content of acrylic copolymer in the finished paper was measured to be 9%.

[0063] Example 3

[0064] 75 parts of chitosan fiber were pulped to obtain pulp M1 with a freeness of 350 mL and a coarseness of 0.2 mg / m.

[0065] 25 parts of polypropylene fiber with a coarseness of 2 mg / m and a freeness of 300 mL were evenly dispersed to obtain slurry M2, wherein the melting point of the polypropylene fiber is 150℃.

[0066] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0067] The mass concentration of pulp M3 was adjusted to 0.6%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0068] The semi-dry paper is immersed in waterborne polyurethane with a mass concentration of 20% reinforcing agent, and then the excess reinforcing agent is expelled from the paper web by a two-roll extruder and dried to obtain semi-finished dialysis paper.

[0069] The semi-finished dialysis paper was hot-pressed at 130℃ to obtain a basis weight of 50 g / m³. 2 The finished dialysis paper was obtained; and the content of acrylic copolymer in the finished paper was measured to be 12%.

[0070] Example 4

[0071] 70 parts of lyocell fiber were pulped to obtain pulp M1 with a freeness of 350 mL and a coarseness of 0.2 mg / m.

[0072] 20 parts of polypropylene fiber with a coarseness of 5 mg / m and a freeness of 500 mL were evenly dispersed to obtain slurry M2, wherein the melting point of the polypropylene fiber is 125℃.

[0073] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0074] The mass concentration of pulp M3 was adjusted to 0.8%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0075] The semi-dry paper sheet is immersed in an acrylic copolymer with a mass concentration of 15% as a reinforcing agent, and then the excess reinforcing agent is expelled from the paper web by a two-roll extruder and dried to obtain a semi-finished dialysis paper.

[0076] The semi-finished dialysis paper was hot-pressed at 140℃ to obtain a basis weight of 65 g / m³. 2 The finished dialysis paper was obtained; and the content of acrylic copolymer in the finished paper was measured to be 9%.

[0077] Example 5

[0078] 75 parts of seaweed fiber were pulped to obtain pulp M1 with a freeness of 300 mL and a coarseness of 0.35 mg / m.

[0079] 25 parts of low-melting-point polyethylene fiber with a coarseness of 10 mg / m and a freeness of 400 mL were evenly dispersed to obtain slurry M2, wherein the melting point of the low-melting-point polyethylene fiber is 100℃.

[0080] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0081] The mass concentration of pulp M3 was adjusted to 0.8%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 60%.

[0082] The semi-dry paper is immersed in waterborne polyurethane with a mass concentration of 20% reinforcing agent, and then the excess reinforcing agent is expelled from the paper web by a two-roll extruder and dried to obtain semi-finished dialysis paper.

[0083] The semi-finished dialysis paper was hot-pressed at 135℃ to obtain a basis weight of 70 g / m³. 2 The finished dialysis paper was obtained; and the content of acrylic copolymer in the finished paper was measured to be 11%.

[0084] Comparative Example 1

[0085] 75 parts of softwood pulp fiber were beating to a freeness of 25SR to obtain pulp M1;

[0086] 25 parts of broadleaf pulp fiber were beating to a freeness of 27SR to obtain pulp M2;

[0087] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0088] The mass concentration of pulp M3 was adjusted to 0.8%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0089] Semi-dry paper sheets are coated with a mixture of alkyl ketene dimer and modified starch, and then dried to obtain the finished dialysis paper.

[0090] Comparative Example 2

[0091] 75 parts of softwood pulp fiber were beating to a freeness of 25SR to obtain pulp M1;

[0092] 25 parts of broadleaf pulp fiber were beating to a freeness of 27SR to obtain pulp M2;

[0093] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0094] The mass concentration of pulp M3 was adjusted to 0.8%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0095] Semi-dry paper sheets are coated with a modified starch solution and then dried to obtain the finished dialysis paper.

[0096] Comparative Example 3

[0097] 75 parts of softwood pulp fiber were beating to a freeness of 30SR to obtain pulp M1;

[0098] 25 parts of broadleaf pulp fiber were beating to a freeness of 32SR to obtain pulp M2;

[0099] Mix slurry M1 and slurry M2 evenly to obtain slurry M3;

[0100] The mass concentration of pulp M3 was adjusted to 0.6%, and the paper was dewatered, pressed, and dried using a long-wire multi-cylinder paper machine to obtain a semi-dry paper sheet with a dryness of 65%.

[0101] Semi-dry paper sheets are coated with a mixture of alkyl ketene dimer and modified starch, and then dried to obtain the finished dialysis paper.

[0102] Example 6 Physical Index Testing

[0103] The dialysis paper obtained using the methods of Examples 1-5 and Comparative Examples 1-3 was used as a sample for tensile strength and air permeability testing:

[0104] Tensile strength: The test method adopts GB / T453-2002 "Determination of tensile strength of paper and paperboard";

[0105] Air permeability: The test method adopts GB / T458-2008 "Determination of air permeability of paper and paperboard";

[0106] The recorded test data is shown in Table 1:

[0107] Table 1. Test results of physical properties of Examples 1-5 and Comparative Examples 1-3

[0108]

[0109] According to the results in Table 1:

[0110] First, the dialysis paper obtained in Examples 1-5 all have a strength greater than 90 N·m / g, which has high strength and further reduces the risk of packaging breakage.

[0111] Second, the dialysis papers obtained in Examples 1-5 all have an air permeability greater than 10 μm (Pa·s). -1 It exhibits good air permeability, which is beneficial for the sterilization of medical devices.

[0112] Third, the tensile index and air permeability of Example 3 are slightly lower than those of other examples, suggesting that the physical properties of the polyolefin fiber used in Example 3 affected the quality indicators of the final product.

[0113] Based on the above, in Examples 1-5, the regenerated fibers with stronger fibrillation and the low-melting-point polyolefin multi-branched fibers exhibited more uniform interweaving between fibers during the molding process. Through hot pressing, the surface of the low-melting-point polyolefin multi-branched fibers melted and bonded with the surrounding fibers, thereby improving the tensile strength of the paper sheet.

[0114] In Comparative Examples 1-3, traditional softwood pulp and hardwood pulp were used for co-papermaking, and the strength of the paper sheet mainly relied on the hydrogen bond combination between fibers. If the strength was to be improved, only by increasing the beating degree of fibers, such as the scheme in Comparative Example 3. However, although increasing the beating degree could improve the strength of the paper sheet, it would also make the paper sheet denser, thus reducing the air permeability of the paper sheet, and it was impossible to balance the air permeability and strength indexes of the dialysis paper.

[0115] In vitro hemolysis test of Example 7

[0116] The dialysis papers obtained by the methods of Examples 1-5 and Comparative Examples 1-3 were used as samples for in vitro hemolysis test: According to ISO 1993-4:2017:

[0117] Experimental animals: New Zealand white rabbits (healthy, male), from Chendun Experimental Animal Breeding Farm Co., Ltd., Songjiang District, Shanghai, license number: SCXK (Shanghai) 2022-0001, quality certificate number: 20220001001461.

[0118] Negative control: 0.9% sodium chloride injection, purchased from Shandong Qidu Pharmaceutical Co., Ltd.

[0119] Positive control: Distilled water, purchased from Guangzhou Watson's Food and Beverage Co., Ltd.

[0120] Test content:

[0121] Preparation of fresh anticoagulated rabbit blood: Mix rabbit blood and 0.9% sodium chloride injection evenly according to the volume ratio of 4:5. Collect 10 mL of blood from healthy adult rabbits, anticoagulate with 2% potassium oxalate, and prepare fresh anticoagulated rabbit blood.

[0122] Preparation of diluted blood: Take 8 mL of fresh anticoagulated rabbit blood and add 10 mL of 0.9% sodium chloride injection for dilution.

[0123] Sample preparation: Weigh 3 portions of test samples, 5 g for each portion, cut them into small segments with a length of 5 cm, and prepare 3 portions for the test according to the ratio (sample: contact liquid volume).

[0124] For the negative control group and the positive control group, take 3 centrifuge tubes respectively, and add 10 mL of 0.9% sodium chloride injection and distilled water to each tube respectively.

[0125] Experimental Procedure: For the test sample group, add 5g of the test sample to each tube, followed by 10mL of sodium chloride injection; for the negative control group, add 10mL of sodium chloride injection to each tube; for the positive control group, add 10mL of distilled water to each tube. Perform three parallel operations per group. Place all tubes in a constant temperature water bath at 37℃±1℃ for 30 minutes. Then, add 0.2mL of diluted rabbit blood to each tube, mix gently, and continue incubating at 37℃±1℃ for another 60 minutes. Pour out the solution from the tubes and centrifuge at 800g for 5 minutes. Aspirate the supernatant into a cuvette and measure the absorbance of each group at 545nm using a spectrophotometer.

[0126] Statistical method: The absorbance of both the test sample group and the control group was taken as the average of three tubes. The absorbance of the negative control tube should not exceed 0.03, and the absorbance of the positive control tube should be 0.8 ± 0.3; otherwise, the test should be repeated. The formula for calculating the hemolysis rate is as follows:

[0127]

[0128] The test results are shown in Table 2.

[0129] Table 2. Results of in vitro hemolysis tests for Examples 1-5 and Comparative Examples 1-3

[0130]

[0131] According to the experimental results in Table 2:

[0132] The hemolysis rate of the test samples in Examples 1-5 was less than 5%, which met the standard requirements; while the hemolysis rate of the test samples in Comparative Examples 1-3 was greater than 5%, which did not meet the standard requirements.

[0133] The dialysis paper provided in this application has a lower hemolysis rate and is safer to use.

[0134] Example 8 In vitro cytotoxicity test

[0135] Test standard: GB / T 16886.5-2017 "Biological evaluation of medical devices - Part 5: In vitro cytotoxicity tests"

[0136] Reference standard: High-density polyethylene.

[0137] Experimental solvent (MEM complete culture medium): 180 mL MEM basal culture medium + 20 mL fetal bovine serum.

[0138] Cells used in the experiment: Mouse fibroblasts L-929, sourced from the Cell Bank of the Chinese Academy of Sciences.

[0139] Pretreatment method for test samples: Take samples with a surface area of ​​30 cm² 2The test sample dialysis paper was placed in a glass container and autoclaved at 115°C for 30 minutes. Then, MEM complete culture medium was used as the extraction solution, and the samples were extracted at 3 cm intervals. 2 Add 10 mL of MEM complete culture medium at a ratio of / mL, and prepare a 100% test sample extract in a constant temperature shaker at 1000 rpm. Blank control pretreatment method: Take 10 mL of MEM complete culture medium and extract it in a constant temperature shaker at 100 rpm and 37℃ for 24 h.

[0140] Negative control pretreatment method: Weigh 2.0012g of high-density polyethylene, clean it, blot it dry with filter paper, place it in a glass container, autoclave at 115℃ for 30min, then use MEM complete culture medium as the extraction medium, add 10mL of MEM complete culture medium at a ratio of 0.2g / mL, and extract in a constant temperature shaker at 100rpm and 37℃ for 24h.

[0141] Preparation of positive control: Take 1 mL of DMSO, add 9 mL of MEM complete culture medium, mix well, and obtain 10 mL of positive control solution containing 10% DMSO.

[0142] Experimental methods: L-929 cells were cultured in MEM complete medium. When the cells nearly converged, they were digested with 0.25% trypsin-EDTA and cultured in MEM complete medium to form 1×10⁻⁶ cells. 5 Cell suspension was prepared at 100 μL / mL. The cell suspension was seeded into 96-well plates with 6 parallel wells per group, 100 μL per well. MEM complete culture medium was added to the outer wells of the 96-well plate at 100 μL per well. The plates were incubated at 37°C in a 5% CO2 incubator for 24 h. The original culture medium was discarded. Fresh complete culture medium was added to the blank control group, negative control extract was added to the negative control group, positive control solution was added to the positive control group, and 100% test sample extract group was added to 100 μL / well. The plates were incubated in a CO2 incubator for another 24 h, and cell morphology was observed under a microscope. The original culture medium was discarded, and 50 μL of MTT solution was added to each well. The plates were incubated for another 2 h, and the plates were carefully shaken. The MTT solution was discarded, and 100 μL of isopropanol was added to each well. The absorbance of each well was measured using a microplate reader at a wavelength of 570 nm (reference wavelength 650 nm).

[0143] Data statistical methods: The raw data are expressed as the mean plus or minus the standard deviation. If the blank OD... 570 If the average value is ≥0.2 and the difference between the average value of the two blank columns and the average value of all blanks is no more than 15%, and the survival rate of 50% of the test sample extract is ≥100% of the test sample extract survival rate, the test system is valid. The degree of cytotoxicity of the test sample should be analyzed and determined. Otherwise, the test should be repeated.

[0144] Calculation of cell viability:

[0145]

[0146] Note: OD570e - mean absorbance of the sample group (negative, positive); OD570b - mean absorbance of the blank control group.

[0147] Cell toxicity judgment: If the cell viability of the 100% test article extract group > 70%, the test article has no cell toxicity.

[0148] The test results are shown in Table 3.

[0149] Table 3 Test results of in vitro cell toxicity of Examples 1 - 5 and Comparative Examples 1 - 3

[0150]

[0151] According to the results in Table 3:

[0152] The dialysis paper prepared in Examples 1 - 5 was subjected to in vitro cell toxicity test, and the results showed that the cell viability was greater than 90%, far higher than 70%, proving that the dialysis paper has no cell toxicity; while the dialysis paper prepared in Comparative Examples 1 - 3 was subjected to in vitro cell toxicity test, and the results showed that the cell viability was less than 70%, proving that the dialysis paper has certain cell toxicity.

[0153] Example 9 Abnormal toxicity test

[0154] The test was carried out according to the "Abnormal Toxicity Test Method" in General Rules 1141 of Part III and Part IV of the Chinese Pharmacopoeia 2020 Edition.

[0155] Test system:

[0156] NIH mice, SPF grade, male, 45, provided by the Guangdong Provincial Medical Experimental Animal Center. Experimental animal production license number: SCXK(Guangdong)2022 - 0002. Experimental animal quality certificate number: 44007200129006. Animal use license number: SYXK(Guangdong)2022 - 0002. Animal experiment certificate number: 00391247.

[0157] Hartley guinea pigs, SPF grade, male, 18, provided by the Guangdong Provincial Medical Experimental Animal Center. Experimental animal production license number: SCXK(Guangdong)2022 - 0002. Experimental animal quality certificate number: 44007200129007. Animal use license number: SYXK(Guangdong)2022 - 0002. Animal experiment certificate number: 00391246.

[0158] Method for preparing the test article: Take an appropriate amount of the test article, at 50L / m 2After rinsing and filtering with purified water, take a small amount of purified water and extract at 100°C. Take the extract for testing.

[0159] The experimental results are shown in Tables 4 and 5.

[0160] Table 4-1 Results of Abnormal Toxicity Tests (Mouse Test Method) for Examples 1-5

[0161]

[0162]

[0163] Table 4-2 Results of Abnormal Toxicity Tests (Mouse Test Method) for Comparative Examples 1-3

[0164]

[0165] According to the experimental results in Table 4:

[0166] Mice were injected with the extracts from Examples 1-5 and observed clinically for 7 days, with their body weight recorded. No abnormal reactions were observed in any of the treatment groups during the experiment, and all animals gained weight and survived, indicating that Examples 1-5 had no abnormal toxicity and met the standards.

[0167] Mice were injected with the extracts of Comparative Examples 1-3 and observed clinically for 7 days, with their body weight recorded. During the experiment, all treatment groups showed symptoms such as anorexia, decreased responsiveness, diarrhea, and polyuria. Some animals died, and the body weight of all animals decreased, indicating that Comparative Examples 1-3 had certain abnormal toxicity and did not meet the standard requirements.

[0168] Table 5. Results of Abnormal Toxicity (Guinea Pig Test Method) of Examples 1-5 and Comparative Examples 1-3

[0169]

[0170] According to the experimental results in Table 5:

[0171] The extracts from Examples 1-5 were injected into guinea pigs, and clinical observation was conducted for 7 days, with body weight recorded. No abnormal reactions were observed in any of the treatment groups during the experiment, and all animals gained weight and survived, indicating that Examples 1-5 had no abnormal toxicity and met the standards.

[0172] Guinea pigs were injected with the extracts of Comparative Examples 1-3 and observed clinically for 7 days, with their weight recorded. All treatment groups showed symptoms such as anorexia, diarrhea, and polyuria during the experiment. Although no animals died, all animals lost more than 10% of their body weight, indicating that Comparative Examples 1-3 had certain abnormal toxicity and did not meet the standard requirements.

[0173] In summary, the dialysis paper and its preparation method provided in this application produce dialysis paper products with high strength and good air permeability. Furthermore, the products meet medical device evaluation standards, exhibit no cytotoxicity or abnormal toxicity, and do not cause hemolysis. They are products with high biosafety and can solve the technical problems mentioned in the background art.

[0174] It should be noted that, for those skilled in the art, the technical features in the above embodiments can be freely combined, and the resulting technical solutions also belong to the embodiments disclosed in this application.

[0175] Furthermore, without departing from the principles of this application, several improvements and modifications may be made to this application, and these improvements and modifications also fall within the protection scope of the claims of this application.

Claims

1. A preparation method of dialysis paper, characterized in that, the preparation method comprises the steps of: a preparation step of pulp M1, wherein regenerated fibers are subjected to a beating treatment to obtain pulp M1; a preparation step of pulp M2, wherein polyolefin fibers are uniformly dispersed to obtain pulp M2; a preparation step of pulp M3, wherein pulp M1 and pulp M2 are uniformly mixed to obtain pulp M3; a step of obtaining a semi-dry paper web, wherein the mass concentration of pulp M3 is adjusted to 0.6-0.8%, and the semi-dry paper web is obtained by dehydration, pressing, and drying; a step of obtaining a semi-finished dialysis paper, wherein the semi-dry paper web is immersed in a reinforcing agent, the excess reinforcing agent of the paper web is removed, and the semi-finished dialysis paper is obtained by drying; a step of obtaining a finished dialysis paper, wherein the semi-finished dialysis paper is subjected to heat pressing to obtain the finished dialysis paper; wherein the freeness of the pulp M1 is 300-350 mL, and the coarseness is 0.2-0.35 mg / m; in the step of obtaining the finished dialysis paper, the heat pressing temperature of the semi-finished dialysis paper is 130-140℃; The dialysis paper prepared by the preparation method comprises components: 70-75 parts of regenerated fibers, 20-30 parts of polyolefin fibers, and 5-15 parts of reinforcing agents, wherein the basis weight of the dialysis paper is 50-85 g / m 2 . the regenerated fibers include at least one of seaweed fibers, lyocell fibers, chitosan fibers, and soybean protein composite fibers; the polyolefin fibers are low-melting-point polyolefin fibers, and include at least one of polyethylene fibers, polypropylene fibers, matrix-fibril type polyolefin fibers, and side-by-side type polyolefin fibers; the reinforcing agent includes at least one of modified xyloglucan, acrylic acid copolymer, and water-based polyurethane; the coarseness of the polyolefin fibers is 0.8-15 mg / m, the freeness is 200-600 mL, and the hot melting temperature is 100-150℃.

2. The method of claim 1, wherein: the reinforcing agent is at least one emulsion of modified xyloglucan, acrylic acid copolymer, and water-based polyurethane, and the mass concentration of the emulsion is 15-20%.

3. The method of claim 1, wherein: the dryness of the semi-dry paper web is 50-80%.

4. The dialysis paper prepared according to the preparation method of claim 1, characterized in that: the coarseness of the polyolefin fibers is 3-10 mg / m, the freeness is 400-500 mL, and the hot melting temperature is 100-135℃.

5. The dialysis paper produced by the production method according to claim 1, characterized by: The dialysis paper has a basis weight of 65-75 g / m 2 .

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