Method for testing the quality of antibacterial chlorine-resistant medical cotton

Abstract

The present application relates to the technical field of medical dressing detection, and discloses a quality detection method of antibacterial chlorine-resistant medical cotton, comprising the following steps: placing a sample to be tested into a constant-temperature and constant-humidity box for balancing; preparing a neutral phosphate buffer treatment solution and dividing it into a test group and a blank group; immersing the sample into the test group and synchronously placing the blank group in the dark; separating and collecting double-track residual liquid, rinsing and dehydrating the sample, and drying; testing the breaking strength and antibacterial rate of the dried sample and the original sample; titrating the residual liquid and the blank residual liquid to obtain the net consumption of effective chlorine; calculating the breaking strength retention rate and the antibacterial rate decay rate, and combining the net consumption of effective chlorine to substitute into a failure cause matrix for discrimination. The present application eliminates systematic errors generated by alkaline hydrolysis and natural evaporation of effective chlorine, realizes quantitative differentiation of physical structure dominant failure and chemical inactivation dominant failure, and provides accurate investigation basis for quality control of medical cotton.

Description

Technical Field

[0001] This invention relates to the field of medical dressing testing technology, and in particular to a quality testing method for antibacterial and chlorine-resistant medical cotton. Background Technology

[0002] Medical cotton faces complex chemical exposures in clinical nursing environments, particularly the routine use of chlorine-containing disinfectants, requiring antibacterial medical cotton to possess adequate chlorine resistance. Current conventional chlorine resistance testing methods typically involve directly immersing cotton samples in a sodium hypochlorite aqueous solution and then observing changes in mechanical properties and antibacterial properties. However, ordinary sodium hypochlorite solutions are strongly alkaline, and cotton cellulose macromolecules undergo glycosidic bond hydrolysis in alkaline liquids. This alkaline hydrolysis-induced fiber breakage can obscure the oxidative damage from available chlorine, causing the measured mechanical degradation to deviate from the material's true chlorine resistance level.

[0003] Conventional testing systems calculate chlorine consumption directly based on the concentration difference of the solution before and after treatment, ignoring the natural volatilization and decomposition of sodium hypochlorite during settling due to temperature and time accumulation. This failure to account for natural loss leads to inflated chlorine consumption data and introduces systematic errors. Furthermore, conventional testing methods ultimately only output surface degradation results for breaking strength and antibacterial rate, leaving the test data at a macroscopic level. When cotton samples exhibit substandard performance, the testing system cannot determine whether the degradation is due to physical structural peeling caused by insufficient cross-linking of the surface coating or chemical inactivation caused by the decomposition of core antibacterial functional groups by free chlorine. Consequently, the test results cannot provide accurate guidance for product formulation and process improvement. Summary of the Invention

[0005] The purpose of this invention is to provide a quality testing method for antibacterial and chlorine-resistant medical cotton, which solves the problem that existing testing methods cannot comprehensively evaluate the performance evolution process of quaternary ammonium salt modified medical cotton in chlorine-containing environments, and it is difficult to accurately locate the physical or chemical causes of material failure, resulting in a lack of reliable basis for product quality monitoring and modification process optimization.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a quality testing method for antibacterial and chlorine-resistant medical cotton, comprising the following steps:

[0007] Select the test sample and the original sample, weigh the total mass of the test sample and balance it to obtain the balanced sample;

[0008] Prepare the treatment solution, and take two equal volumes of the treatment solution as the test group solution and the blank group solution, respectively.

[0009] The equilibrated test piece is immersed in the test group solution, while the blank group solution remains without test pieces and is simultaneously placed in the dark. After treatment, the equilibrated test piece and the test group solution are separated into solid and liquid components to obtain the separated test piece and residual treatment solution. The residual treatment solution and the blank group solution are respectively referred to as test residual solution and blank residual solution.

[0010] The separated test pieces are rinsed, dehydrated, and dried to obtain dried test pieces;

[0011] The dried test piece and the original test piece were simultaneously tested to obtain the longitudinal tensile strength and antibacterial rate, respectively.

[0012] Take equal volumes of the blank residual liquid and the test residual liquid, respectively, and titrate them with standard titration solution. Calculate the net effective chlorine consumption based on the total mass of the test sample piece.

[0013] By comparing the longitudinal tensile strength and antibacterial rate of the dried test piece and the original test piece, the tensile strength retention rate and antibacterial rate decay rate are calculated. The tensile strength retention rate, the antibacterial rate decay rate, and the effective chlorine net consumption are then substituted into the failure attribution matrix and compared with the pre-set threshold values ​​of each corresponding indicator.

[0014] By adopting the above technical solution, this detection method has the following beneficial effects:

[0015] This method establishes a correlation between the macroscopic performance degradation and microscopic chemical consumption of materials, constructing a multi-dimensional quality evaluation system. The specific reaction and discrimination mechanisms are as follows:

[0016] A dual-track control system was established to eliminate interference from natural depletion: Since sodium hypochlorite undergoes a certain degree of spontaneous decomposition during settling, a blank solution without test pieces was set up to obtain the natural exposure loss of the treated solution under the same conditions. Subsequently, by subtracting the titration results, the net effective chlorine consumption solely due to the test piece reaction was precisely determined.

[0017] Decoupling the two-way degradation pathway of physical damage and chemical deactivation: The material faces two types of degradation reactions in chlorine-containing treatment solutions.

[0018] One is the skeleton destruction reaction. The effective chlorine component in the treatment solution attacks the cellulose macromolecular skeleton of cotton fibers, breaks the glycosidic bonds, and leads to a decrease in longitudinal breaking strength.

[0019] Secondly, there is the antibacterial group consumption reaction. Available chlorine attacks the quaternary ammonium salt active center grafted onto cellulose, triggering a chemical substitution reaction, which leads to a decrease in the antibacterial rate.

[0020] Multi-level index combination to infer failure causes: Effective chlorine net consumption is used as a quantitative indicator of chemical reaction intensity, combined with tensile strength retention rate and antibacterial rate decay rate for matrix verification. Individual index tests can only evaluate the macroscopic performance of the product, while combined comparisons can accurately pinpoint the specific degradation pathways leading to material failure based on the coupling relationship between these indicators.

[0021] Preferably, when preparing the treatment solution, the sodium hypochlorite stock solution is diluted with phosphate buffer solution with a concentration of 0.05-0.2 mol / L to prepare a solution with an initial available chlorine concentration of 450-550 mg / L and a pH locked at 6.5-7.5.

[0022] By employing the above technical solution, phosphate buffer can neutralize the acidic and alkaline substances released during the decomposition of sodium hypochlorite, maintaining a constant pH in the liquid phase system. Locking the pH within a near-neutral range ensures that a large amount of available chlorine in the aqueous solution exists in the form of hypochlorous acid molecules. Hypochlorous acid molecules are uncharged and small in size, easily penetrating the fiber surface and permeating into the internal space, ensuring high reproducibility of accelerated exposure tests.

[0023] Preferably, when immersing the balanced test piece in the test group solution, the ratio of the total mass of the test sample to the volume of the solution is controlled to be 1:50-1:200 g / mL;

[0024] The conditions for synchronous light-protected static placement are: temperature set at 35-40℃, time set at 20-60min.

[0025] By adopting the above technical solution, the set temperature range closely matches the actual temperature of the human body surface and the environment of a typical ward, making the exposure test closely resemble the actual application scenario of medical consumables. By controlling the ratio of the total mass of the test sample to the volume of the solution and the reaction time, sufficient liquid-phase mass transfer channels are established to prevent reaction distortion caused by a sudden drop in the local effective chlorine concentration at the solid-liquid interface.

[0026] Preferably, before titrating with the standard titration solution, take the same volume of the blank residual solution and the test residual solution and place them in iodine flasks respectively. Add potassium iodide solution and sulfuric acid solution to each of the two iodine flasks. After reacting in the dark, add starch indicator and perform titration.

[0027] The standard titration solution used is sodium thiosulfate standard titration solution.

[0028] The specific logic for calculating the net effective chlorine consumption is as follows: subtract the volume of the standard titration solution consumed by the blank residual solution from the volume of the standard titration solution consumed by the test residual solution to obtain the difference; multiply the difference by the concentration of the sodium thiosulfate standard titration solution, the chlorine molar mass constant, and the initial total volume of the treatment solution to obtain the product; divide the product by the sampling volume; and finally divide by the total mass of the test sample to obtain the net effective chlorine consumption.

[0029] By employing the above technical solution, iodometric titration can achieve high-precision quantification of residual available chlorine. Under strongly acidic conditions, the residual available chlorine completely oxidizes potassium iodide and precipitates free iodine. Subsequently, the free iodine is reduced using a sodium thiosulfate standard titration solution, and a starch indicator sharply captures the endpoint color change reaction. The calculation logic strictly follows the step of dividing by the sample volume and the total mass of the test sample, accurately converting the difference in titration volume into the actual chlorine mass consumed per unit mass of medical cotton, thus unifying the basic dimensions for data evaluation.

[0030] Preferably, the determination rules for the failure attribution matrix include:

[0031] The preset threshold values ​​for each corresponding indicator include the antibacterial rate attenuation threshold and the tensile strength retention threshold. The antibacterial rate attenuation threshold is set to 5%-10%, and the tensile strength retention threshold is set to 80%-90%.

[0032] When the measured antibacterial rate attenuation rate is less than or equal to the attenuation threshold, and the tensile strength retention rate is greater than or equal to the retention threshold, the sample is deemed to have qualified antibacterial and chlorine-resistant properties.

[0033] The determination rule also includes: when the measured tensile strength retention rate is greater than or equal to the retention threshold, but the antibacterial rate decay rate is greater than the decay threshold, and the effective chlorine net consumption is greater than 6.5 mg / g, it is determined that chemical inactivation-dominated failure has occurred.

[0034] When the measured antibacterial rate attenuation rate is less than or equal to the attenuation threshold, but the tensile strength retention rate is less than the retention threshold, and the effective chlorine net consumption is less than or equal to 1.5 mg / g, it is determined that a physical structure-dominated failure has occurred.

[0035] By adopting the above technical solution, quantitative state boundary indicators were established. When the antibacterial rate decreases and the net effective chlorine consumption is greater than 6.5 mg / g, it indicates that the effective chlorine mainly attacks the antibacterial groups, and this is judged as chemical inactivation. When the breaking strength drops sharply but the net effective chlorine consumption is at or below 1.5 mg / g, it indicates that trace amounts of effective chlorine directly cleave the main cellulose chain, causing macromolecular degradation, while the overall structure of the quaternary ammonium salt groups remains intact, and this is judged as physical structural degradation. The above attribution logic clarifies the direction for improvement in product quality control.

[0036] Preferably, when weighing and balancing the total mass of the sample to be tested, the sample is placed in a constant temperature and humidity chamber, with the temperature set at 20-25℃ and the relative humidity at 60%-70%, and balancing is carried out for 24-48 hours.

[0037] When synchronously avoiding light and allowing the material to stand still, a constant temperature chamber is selected as the standing equipment, and a black rubber light shield is added to the outside of the constant temperature chamber to block the light source.

[0038] By adopting the above technical solution, constant temperature and humidity balance eliminates mass fluctuations caused by natural moisture absorption, ensuring that the total mass of the test sample, which serves as the denominator in the effective chlorine net consumption calculation system, remains constant and accurate. A light-shielding cover is added to isolate external visible and ultraviolet light, blocking the photocatalytic self-decomposition pathway of hypochlorite ions, ensuring that the loss is entirely generated from the reaction kinetics process involving the test sample.

[0039] Preferably, the rinsing, dehydration, and drying operations are as follows:

[0040] The separated test pieces were rinsed in deionized water, the surface moisture was absorbed with filter paper, and then forced to dry in a standard environment with a temperature of 20-25℃ and a relative humidity of 45%-55%RH for 3-6 hours.

[0041] During the testing, a constant-rate elongation tensile testing machine was used to obtain the longitudinal breaking strength, and Staphylococcus aureus was used as the experimental strain for shaking contact culture and plate counting to obtain the antibacterial rate.

[0042] By employing the above technical solution, deionized water is used to wash away free chlorine residing within the mesh-like fibers, thus blocking secondary chain reactions. Forced drying in a standard environment with specific relative humidity (45%-55%RH) restores the fibers' normal mechanical morphology, eliminating the physical plasticizing effect of free moisture on the tensile testing process. Contact culture with Staphylococcus aureus directly demonstrates the bio-killing activity of the positively charged quaternary ammonium salt antibacterial groups in disrupting bacterial cell membranes.

[0043] Preferably, the test sample and the original sample are modified medical cotton prepared in advance through the following processes:

[0044] Immerse 100 parts by weight of medical degreased cotton fibers completely in an alkaline solution containing 2-8 parts by weight of sodium hydroxide, control the system bath ratio to be 1:20-1:50 g / mL, and perform alkalization pretreatment at a temperature of 40-60℃ for 30-60 min.

[0045] After pretreatment, add 5-20 parts by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution to the system, and heat the system to 65-85℃ for isothermal etherification grafting reaction for 2-4 hours;

[0046] After the reaction was completed, the system was neutralized to neutral with acetic acid solution. The reaction product was washed until the conductivity of the eluent remained constant. The reaction product was dried at 60-80℃ to constant weight to obtain quaternary ammonium salt modified medical cotton, which was then divided into test sample pieces and original sample pieces.

[0047] In summary, the present invention has at least one of the following beneficial technical effects:

[0048] 1. This invention calculates the effective chlorine net consumption by simultaneously setting the blank group solution and the test group solution to stand in the dark, and then titrating the blank residual solution and the test residual solution with standard titration solution respectively. This dual-track calibration method pre-deducts the difference in free chlorine volatilization and decomposition caused by the accumulation of temperature and time during the constant temperature standing process. Compared with directly using theoretical concentration conversion, dual-track titration eliminates the systematic error caused by natural loss of environmental background, so that the final effective chlorine net consumption objectively reflects the chlorine equivalent consumed by the actual reaction on the sample surface, ensuring the quantitative accuracy of chemical detection data.

[0049] 2. This invention uses phosphate buffer to dilute sodium hypochlorite stock solution and prepares a neutral solution as the treatment solution. Conventional sodium hypochlorite aqueous solution is alkaline, which easily causes hydrolysis of the glycosidic bonds in the natural cellulose molecular chain, leading to fiber breakage and a decrease in mechanical strength. The neutral buffer system inhibits the damage of cellulose by hydroxide ions and eliminates the interference of structural shedding caused by alkaline hydrolysis, so that the measured longitudinal tensile strength retention rate purely reflects the material's true performance in resisting effective chlorine oxidation.

[0050] 3. This invention establishes a failure attribution matrix, incorporating the breaking strength retention rate, antibacterial rate decay rate, and effective chlorine net consumption into the matrix and comparing them with a set threshold for judgment. Conventional testing can only output macroscopic results of mechanical and microbiological aspects, failing to identify the intrinsic mechanism of degradation. By introducing effective chlorine net consumption as a judgment dimension, the judgment matrix can attribute the phenomenon of low chlorine consumption combined with low strength retention to physical structure-dominated failure, and diagnose the phenomenon of high chlorine consumption combined with high antibacterial rate decay as chemical inactivation-dominated failure. This provides an accurate basis for mechanism investigation for the research and development and quality improvement of antibacterial cotton. Attached Figure Description

[0051] Figure 1 A comparative test graph showing the retention rate of tensile strength and the attenuation rate of antibacterial activity for different types of samples;

[0052] Figure 2 A comparative test chart showing the net available chlorine consumption of different types of samples;

[0053] Figure 3 A comparison chart of the fracture strength retention rates of the buffered and unbuffered samples;

[0054] Figure 4 A comparison of the mass change curves of flocculent shedding between buffered and unbuffered samples;

[0055] Figure 5 A comparison chart of uncalibrated available chlorine consumption and dual-track calibrated net available chlorine consumption;

[0056] Figure 6 A comparison graph showing the fluctuation curves of theoretical titration volume, blank residual liquid consumption volume, and test residual liquid consumption volume;

[0057] Figure 7 A comparison chart of the relative standard deviations of data from the standardized drying group and the non-standardized drying group;

[0058] Figure 8 This is a comparison of the fluctuation curves of the fracture strength retention rate between the standardized drying group and the non-standardized drying group under continuous independent testing. Detailed Implementation

[0059] The technical solutions of the present invention will be clearly and completely described below with reference to embodiments, comparative examples, and test examples. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0060] Preparation Examples 1-3:

[0061] Preparation Example 1:

[0062] This preparation example provides a method for preparing a test sample of quaternary ammonium salt modified medical cotton, including the following steps:

[0063] (1) Weigh 2 parts by mass of sodium hydroxide and dissolve it in deionized water to prepare an alkaline solution; immerse 100 parts by mass of medical degreased cotton fiber completely in the alkaline solution and control the system bath ratio to be 1:20 g / mL; and perform alkalization pretreatment for 30 min under constant temperature conditions of 40℃.

[0064] (2) After the alkalization pretreatment is completed, 5 parts by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution are slowly added dropwise to the system; after the addition is completed, the reaction system is heated to 65°C and the etherification grafting reaction is carried out at a constant temperature for 2 hours.

[0065] (3) After the reaction is completed, the reaction product is taken out and the reaction system is neutralized to neutral with 0.1 mol / L acetic acid solution. Then, the reaction product is washed repeatedly with deionized water until the conductivity of the eluent remains constant. Finally, the reaction product is dried in a 60℃ oven to constant weight to obtain the quaternary ammonium salt modified medical cotton sample to be tested. It is then cut into test sample pieces and original sample pieces.

[0066] Preparation Example 2:

[0067] This preparation example provides a method for preparing a test sample of quaternary ammonium salt modified medical cotton, including the following steps:

[0068] (1) Weigh 5 parts by mass of sodium hydroxide and dissolve it in deionized water to prepare an alkaline solution; immerse 100 parts by mass of medical degreased cotton fiber completely in the alkaline solution and control the system bath ratio to be 1:35 g / mL; and perform alkalization pretreatment for 45 min under constant temperature conditions of 50℃.

[0069] (2) After the alkalization pretreatment is completed, 12 parts by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution are slowly added dropwise to the system; after the addition is completed, the reaction system is heated to 75°C and the etherification grafting reaction is carried out at a constant temperature for 3 hours.

[0070] (3) After the reaction is completed, the reaction product is taken out and the reaction system is neutralized to neutral with 0.1 mol / L acetic acid solution; then the reaction product is repeatedly washed with deionized water until the conductivity of the eluent remains constant; finally, the reaction product is placed in a 70℃ oven and dried to constant weight to obtain the quaternary ammonium salt modified medical cotton sample to be tested, which is then cut into test sample pieces and original sample pieces.

[0071] Preparation Example 3:

[0072] This preparation example provides a method for preparing a test sample of quaternary ammonium salt modified medical cotton, including the following steps:

[0073] (1) Weigh 8 parts by mass of sodium hydroxide and dissolve it in deionized water to prepare an alkaline solution; immerse 100 parts by mass of medical degreased cotton fiber completely in the alkaline solution and control the system bath ratio to be 1:50 g / mL; and perform alkalization pretreatment for 60 min under constant temperature conditions of 60℃.

[0074] (2) After the alkalization pretreatment is completed, 20 parts by mass of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution are slowly added dropwise to the system; after the addition is completed, the reaction system is heated to 85°C and the etherification grafting reaction is carried out at a constant temperature for 4 hours.

[0075] (3) After the reaction is completed, the reaction product is taken out and the reaction system is neutralized to neutral with 0.1 mol / L acetic acid solution; then the reaction product is repeatedly washed with deionized water until the conductivity of the eluent remains constant; finally, the reaction product is placed in an 80℃ oven to dry to constant weight, and the quaternary ammonium salt modified medical cotton sample is obtained. It is then cut into test sample pieces and original sample pieces.

[0076] Examples 1-3:

[0077] Example 1:

[0078] This embodiment provides a quality testing method for antibacterial and chlorine-resistant medical cotton, including the following steps:

[0079] (1) Sample pretreatment and equilibration: Quaternary ammonium salt modified medical cotton was cut to a size of 4.0cm × 4.0cm and divided into test sample pieces and original sample pieces. The sample quantity for each test batch was 5 pieces. The total mass of the test sample pieces was recorded as follows: The mass was measured to be 1.250g. The sample to be tested was placed in a constant temperature and humidity chamber, with the temperature set at 20℃ and the relative humidity at 60%RH, and kept equilibrated for 24 hours to obtain the equilibrated sample.

[0080] (2) Preparation of standardized chlorine-resistant treatment solution: Dilute the sodium hypochlorite stock solution with 0.05 mol / L phosphate buffer to prepare the initial effective chlorine concentration. The treatment solution was prepared with a concentration of 450 mg / L and a pH locked at 6.5; two equal volumes were measured. 62.5 mL of the treatment solution was used as the test group solution and the blank group solution, respectively, and the ratio of the sample mass to the solution volume was controlled to be 1:50 g / mL.

[0081] (3) Simulated clinical exposure and residual liquid collection: The equilibrated test strips were immersed in the test group solution, while the blank group solution was kept without test strips; a constant temperature chamber was used as the settling device, and a black rubber light shield was added to the outside of the constant temperature chamber to block the light source, and the test strips were set in the dark at 35°C for 20 minutes; after the treatment, the test strips and the test group solution were separated into solid and liquid, and the separated test strips and residual treatment liquid were obtained. The residual treatment liquid and the blank group solution were recorded as test residual liquid and blank residual liquid, respectively.

[0082] (4) Rinse, dehydrate and dry: Rinse the separated test pieces in deionized water 3 times (5s each time), use filter paper to absorb the surface moisture for dehydration, and then place them in a standard environment with a temperature of 20℃ and a relative humidity of 45%RH for forced drying for 3h to obtain dried test pieces.

[0083] (5) Synchronous detection: The dried test pieces and the original test pieces were tested simultaneously; the longitudinal breaking strength was obtained by using a constant speed elongation tensile testing machine (clamping distance 100 mm, tensile speed 50 mm / min), and the shedding of flocculent material from the test pieces was rated; Staphylococcus aureus was used as the experimental strain for shaking contact culture (inoculation concentration 1.0 × 10⁵ cfu / mL, contact for 24 h) and plate counting was performed to obtain the longitudinal breaking strength and antibacterial rate respectively.

[0084] (6) Dynamic titration: Take equal volumes of each titrator. Place 10.0 mL of blank solution and test solution in iodine flasks. Add 5 mL of 5 wt% potassium iodide solution and 10 mL of 0.5 mol / L sulfuric acid solution to each iodine flask, and react in the dark for 5 min. Select the appropriate concentration. Titrate with a 0.01 mol / L sodium thiosulfate standard solution, adding 0.5 wt% starch indicator near the endpoint until the blue color disappears; record the volume of blank residue consumed. and the volume consumed by the test residual liquid Combined with the total mass of the sample piece to be tested Calculate the net consumption of available chlorine using the following formula. :

[0085] ;

[0086] In the formula, 35.45 is the molar mass constant of chlorine.

[0087] (7) Judgment and comparison: By comparing the longitudinal tensile strength and antibacterial rate of the dried test piece and the original test piece, the antibacterial rate decay rate is calculated. and fracture strength retention rate Set the attenuation threshold to 5% and the retention threshold to 80%; set the fracture strength retention rate. Antibacterial rate attenuation rate Net consumption of available chlorine Substitute them together into the failure attribution matrix and compare them with a set threshold for judgment: when measured ≤5% and When the antibacterial and chlorine-resistant properties of the sample are ≥80%, the sample is deemed to have passed the test.

[0088] Example 2:

[0089] This embodiment provides a quality testing method for antibacterial and chlorine-resistant medical cotton, including the following steps:

[0090] (1) Sample pretreatment and equilibration: Quaternary ammonium salt modified medical cotton with a size of 5.0cm × 5.0cm was cut and divided into test sample pieces and original sample pieces. The sample quantity for each test batch was 5 pieces. The total mass of the test sample pieces was recorded as follows: The mass was measured to be 2.000g. The sample to be tested was placed in a constant temperature and humidity chamber, with the temperature set at 23℃ and the relative humidity at 65%RH, and kept equilibrated for 36 hours to obtain the equilibrated sample.

[0091] (2) Preparation of standardized chlorine-resistant treatment solution: Dilute the sodium hypochlorite stock solution with 0.1 mol / L phosphate buffer to prepare the initial effective chlorine concentration. The treatment solution was prepared at 500 mg / L with a pH locked at 7.0; two equal volumes were measured. 200.0 mL of the treatment solution was used as the test group solution and the blank group solution, respectively, and the ratio of the sample mass to the solution volume was controlled to be 1:100 g / mL.

[0092] (3) Simulated clinical exposure and residual liquid collection: The equilibrated test strips were immersed in the test group solution, while the blank group solution was kept without test strips; a constant temperature chamber was used as the settling device, and a black rubber light shield was added to the outside of the constant temperature chamber to block the light source, and the test strips were set in the dark at 37°C for 30 minutes; after the treatment, the test strips and the test group solution were separated into solid and liquid, and the separated test strips and residual treatment liquid were obtained. The residual treatment liquid and the blank group solution were recorded as test residual liquid and blank residual liquid, respectively.

[0093] (4) Rinse, dehydrate and dry: Rinse the separated test pieces three times in deionized water (10s each time), use filter paper to absorb the surface moisture for dehydration, and then place them in a standard environment with a temperature of 23℃ and a relative humidity of 50%RH for forced drying for 4h to obtain dried test pieces.

[0094] (5) Synchronous detection: The dried test pieces and the original test pieces were tested simultaneously; the longitudinal breaking strength was obtained by using a constant speed elongation tensile testing machine (clamping distance 150 mm, tensile speed 100 mm / min), and the shedding of flocculent material from the test pieces was rated; Staphylococcus aureus was used as the experimental strain for shaking contact culture (inoculation concentration 2.0 × 10⁵ cfu / mL, contact for 24 h) and plate counting was performed to obtain the longitudinal breaking strength and antibacterial rate respectively.

[0095] (6) Dynamic titration: Take equal volumes of each titrator. Place 25.0 mL of blank solution and test solution in iodine flasks. Add 10 mL of 10 wt% potassium iodide solution and 15 mL of 1.0 mol / L sulfuric acid solution to each iodine flask, and react in the dark for 5 min. Select the appropriate concentration. Titrate with a 0.015 mol / L sodium thiosulfate standard solution, adding 1.0 wt% starch indicator near the endpoint until the blue color disappears; record the volume of blank residue consumed. and the volume consumed by the test residual liquid Combined with the total mass of the sample piece to be tested Calculate the net consumption of available chlorine using the following formula. :

[0096] ;

[0097] (7) Judgment and comparison: By comparing the longitudinal tensile strength and antibacterial rate of the dried test piece and the original test piece, the antibacterial rate decay rate is calculated. and fracture strength retention rate Set the attenuation threshold to 7.5% and the retention threshold to 85%; set the fracture strength retention rate. Antibacterial rate attenuation rate Net consumption of available chlorine Substitute them together into the failure attribution matrix and compare them with a set threshold for judgment: when measured ≥85% but >7.5% and When a value greater than 6.5 mg / g is found, chemical inactivation-dominated failure is considered to have occurred.

[0098] Example 3:

[0099] This embodiment provides a quality testing method for antibacterial and chlorine-resistant medical cotton, including the following steps:

[0100] (1) Sample pretreatment and equilibration: Quaternary ammonium salt modified medical cotton with a size of 6.0cm×6.0cm was cut and divided into test sample pieces and original sample pieces. The sample quantity for each test batch was 5 pieces. The total mass of the test sample pieces was recorded as follows: The mass was measured to be 2.850g. The sample to be tested was placed in a constant temperature and humidity chamber, with the temperature set at 25℃ and the relative humidity at 70%RH, and kept equilibrated for 48h to obtain the equilibrated sample.

[0101] (2) Preparation of standardized chlorine-resistant treatment solution: Dilute the sodium hypochlorite stock solution with 0.2 mol / L phosphate buffer to prepare the initial effective chlorine concentration. The treatment solution was prepared with a concentration of 550 mg / L and a pH locked at 7.5; two equal volumes were measured. 570.0 mL of the treatment solution was used as the test group solution and the blank group solution, respectively, and the ratio of the sample mass to the solution volume was controlled to be 1:200 g / mL.

[0102] (3) Simulated clinical exposure and residual liquid collection: The equilibrated test strips were immersed in the test group solution, while the blank group solution was kept without test strips; a constant temperature chamber was used as the settling device, and a black rubber light shield was added to the outside of the constant temperature chamber to block the light source, and the test strips were set in the dark at 40℃ and the time was set at 60min; after the treatment, the test strips and the test group solution were separated into solid and liquid, and the separated test strips and residual treatment liquid were obtained. The residual treatment liquid and the blank group solution were recorded as test residual liquid and blank residual liquid, respectively.

[0103] (4) Rinse, dehydrate and dry: Rinse the separated test pieces in deionized water 5 times (15s each time), use filter paper to absorb the surface moisture for dehydration, and then place them in a standard environment with a temperature of 25℃ and a relative humidity of 55%RH for forced drying for 6h to obtain dried test pieces.

[0104] (5) Synchronous detection: The dried test pieces and the original test pieces were tested simultaneously; the longitudinal breaking strength was obtained by using a constant speed elongation tensile testing machine (clamping distance 200 mm, tensile speed 200 mm / min), and the shedding of flocculent material from the test pieces was rated; Staphylococcus aureus was used as the experimental strain for shaking contact culture (inoculation concentration 3.0 × 10⁵ cfu / mL, contact for 24 h) and plate counting was performed to obtain the longitudinal breaking strength and antibacterial rate respectively.

[0105] (6) Dynamic titration: Take equal volumes of each titrator. Place 50.0 mL of blank solution and test solution in iodine flasks. Add 15 mL of 15 wt% potassium iodide solution and 20 mL of 2.0 mol / L sulfuric acid solution to each iodine flask, and react in the dark for 5 min. Select the appropriate concentration. Titrate with a 0.02 mol / L sodium thiosulfate standard solution, adding 2.0 wt% starch indicator near the endpoint until the blue color disappears; record the volume of blank residue consumed. and the volume consumed by the test residual liquid Combined with the total mass of the sample piece to be tested Calculate the net consumption of available chlorine using the following formula. :

[0106] ;

[0107] (7) Judgment and comparison: By comparing the longitudinal tensile strength and antibacterial rate of the dried test piece and the original test piece, the antibacterial rate decay rate is calculated. and fracture strength retention rate Set the attenuation threshold to 10% and the retention threshold to 90%; set the fracture strength retention rate. Antibacterial rate attenuation rate Net consumption of available chlorine Substitute them together into the failure attribution matrix and compare them with a set threshold for judgment: when measured ≤10% but <90% and When the concentration is less than or equal to 1.5 mg / g, a physical structure-dominated failure is determined to have occurred.

[0108] Comparative Examples 1-3:

[0109] Comparative Example 1:

[0110] Compared with Example 2, the difference is that in step (2), phosphate buffer is not used, and deionized water is directly used to dilute the sodium hypochlorite stock solution to prepare the initial effective chlorine concentration. The treatment solution was prepared with a concentration of 500 mg / L and a pH locked at 10.2. All other steps and parameters were exactly the same as in Example 2.

[0111] Comparative Example 2:

[0112] Compared with Example 2, the difference is that in step (2) and step (3), the preparation of the blank solution without test pieces is omitted and the solution is left to stand in the dark, and the blank residue is not collected; in step (6), dynamic titration is performed without blank residue, and the initial effective chlorine concentration is directly selected in the calculation formula. The calculated theoretical titration volume serves as Substitute the values ​​into the calculation, and follow the same steps and parameters as in Example 2.

[0113] Comparative Example 3:

[0114] Compared with Example 2, the difference is that in step (4), after using filter paper to absorb the surface moisture for dehydration, the test piece is not placed in a standard environment for forced drying. Instead, the test piece is directly subjected to synchronous detection in step (5). The other steps and parameters are exactly the same as in Example 2.

[0115] Test Examples 1-4:

[0116] Test Example 1: Accuracy Test of Logical Judgment for Failure Attribution Matrix

[0117] Experimental steps:

[0118] Quaternary ammonium salt modified medical cotton prepared with different formulation systems was selected as the test object and divided into standard sample A, physical defect sample B with insufficient surface modifier adhesion, and chemical resistance deficiency sample C containing unstable chemical functional groups. Five test sample pieces were prepared in parallel for each test object.

[0119] Following the quality testing method and steps disclosed in Example 2, all test pieces were simultaneously subjected to buffered standardized chlorine-resistant exposure treatment, and the residual liquid was quickly collected and separated into solid and liquid phases after the specified treatment time was completed.

[0120] Simultaneously, longitudinal tensile strength and Staphylococcus aureus inhibition rate were tested on the dried test specimens after standardized forced drying and locking. The corresponding tensile strength retention rates were calculated by comparing the results. Same antibacterial rate attenuation rate .

[0121] The test residue obtained after separation was dynamically titrated with the blank residue using a 0.015 mol / L sodium thiosulfate standard titration solution. The volume difference was recorded, and the net effective chlorine consumption was calculated according to the formula. .

[0122] Extract the numerical variable combination corresponding to each group of samples, substitute it into the failure attribution matrix for comparison and judgment, and read and output the final diagnostic judgment conclusion.

[0123] Experimental data:

[0124] Table 1. Objective Quantitative Data Table for Failure Attribution Matrix Verification Test

[0125] Sample number Sample type Antibacterial rate attenuation rate Ra (%) Fracture strength retention rate Rp (%) Net available chlorine consumption ΔCl (mg / g) Matrix determination conclusion A Standard Sample 3.82 92.14 4.13 Antibacterial and chlorine-resistant properties are qualified B Physical defect samples 1.14 71.32 0.94 Physical structure-dominated failure C Chemical resistance missing samples 21.68 88.75 8.91 Chemical inactivation-dominated failure

[0126] according to Figure 1 same Figure 2 The test data presented demonstrates how the failure attribution matrix quantitatively decouples the complex failure modes of medical cotton. Conventional testing primarily relies on the output of mechanical tensile fracture results and microbial inoculation counts, making it difficult to clarify the intrinsic mechanisms of material degradation. By introducing the effective chlorine net consumption as a benchmark variable for the depth of chemical reaction, the determination system gains the ability to infer the causes of failure.

[0127] like Figure 1 As shown, the fracture strength retention rate of the physically defective samples decreased to 71.32%, exhibiting significant macroscopic mechanical degradation. However... Figure 2 The data showed that the net effective chlorine consumption of the sample was only 0.94 mg / g. This low chlorine consumption indicates that the cotton surface did not undergo a vigorous redox reaction with the effective chlorine in the treatment solution. The loss of strength was attributed to insufficient cross-linking of the surface-modified coating, leading to exposure of the internal natural cellulose skeleton and subsequent erosion by the fluid environment, resulting in structural delamination. The failure attribution matrix, utilizing the combination of low chlorine consumption and low strength retention, attributes the failure phenomenon to physical structure as the primary factor.

[0128] For samples lacking chemical resistance, Figure 1 This reflects that the tensile strength retention rate remained at a relatively high level of 88.75%, but the antibacterial rate decline rate jumped to 21.68%. (Simultaneous observation) Figure 2 The effective chlorine consumption increased to 8.91 mg / g. This high chlorine consumption data confirms that the surface antibacterial chemically modified layer was drastically decomposed by free chlorine, leading to the inactivation of the core antibacterial functional groups. In this process, the surface chemical layer acts as a barrier to consume free chlorine, objectively slowing down the erosion of the internal cellulose skeleton, resulting in a combination of high retention and high antibacterial attenuation. Based on this data characteristic, the judgment system accurately diagnosed it as a chemically inactivated-dominated failure.

[0129] Standard samples in Figure 1 same Figure 2 All physical and chemical indicators were within the preset safety range. Test data demonstrate that the multidimensional judgment matrix eliminates the mutual interference between physical loss and chemical oxidation in macroscopic characterization, providing a clear quantitative basis for quality control of antibacterial and chlorine-resistant medical cotton.

[0130] Test Example 2: Comparative Test of pH Buffer System in Eliminating Pseudo-Physical Degradation Interference

[0131] Experimental steps:

[0132] Ten test samples of quaternary ammonium salt modified medical cotton with a size of 5.0cm×5.0cm were cut and placed in a constant temperature and humidity chamber. The temperature was set at 23℃ and the relative humidity at 50%RH for 24 hours. The samples were divided into two groups of five, and the initial mass of each group was recorded.

[0133] Two treatment solutions with an initial effective chlorine concentration of 500 mg / L were prepared. The first group was prepared by diluting the sodium hypochlorite stock solution with 0.1 mol / L phosphate buffer to a pH of 7.0, and this was designated as the buffer solution. The second group was prepared by directly diluting the sodium hypochlorite stock solution with deionized water to a pH of 10.2, and this was designated as the unbuffered solution.

[0134] The two groups of balanced test pieces were completely immersed in the buffer solution and the unbuffered solution, respectively, with the ratio of test piece mass to solution volume controlled at 1:100 g / mL. They were then placed in a 37℃ constant temperature incubator with a black rubber light shield to avoid light and stand for 30 minutes.

[0135] After the treatment time is over, the sample is removed and the residual treatment liquid is filtered using a microporous membrane with a pore size of 45 μm. The cotton flocculent material obtained from the filtration is collected and transferred to weighing paper.

[0136] The separated main block sample was quickly rinsed three times in deionized water, and the surface moisture of the sample was absorbed by filter paper for dehydration. Then, the sample and the flocculent obtained by vacuum filtration were placed in a standard environment with a temperature of 23℃ and a relative humidity of 50%RH for forced drying for 4 hours.

[0137] The mass of the dried flocculent material was weighed using an analytical balance; the longitudinal breaking strength of two sets of main block specimens was obtained using a constant speed elongation tensile testing machine, with the clamping distance set at 150 mm and the tensile speed at 100 mm / min, and the breaking strength retention rate was calculated by comparing it with the original specimen.

[0138] Experimental data:

[0139] Table 2. Objective Quantitative Data Table of Comparative Verification Test of Buffer Systems

[0140] Test group Sample number Initial fracture strength (N) Fracture strength (N) after treatment Fracture strength retention rate (%) Mass of flocculent material detached (mg) Buffer group (pH 7.0) Test 1 42.15 38.64 91.67 1.8 Buffer group (pH 7.0) Test 2 41.82 37.91 90.65 2.1 Buffer group (pH 7.0) Test 3 43.04 39.55 91.89 1.5 Buffer group (pH 7.0) Test 4 42.66 38.12 89.36 2.4 Buffer group (pH 7.0) Test 5 41.97 38.38 91.45 1.7 Unbuffered group (pH 10.2) Test 1 42.31 30.14 71.24 18.6 Unbuffered group (pH 10.2) Test 2 41.75 27.53 65.94 22.3 Unbuffered group (pH 10.2) Test 3 42.88 29.86 69.64 19.1 Unbuffered group (pH 10.2) Test 4 42.09 26.11 62.03 24.5 Unbuffered group (pH 10.2) Test 5 43.12 31.05 72.01 16.7

[0141] according to Figure 3 The bar chart data shows that the cotton samples without cushioning had a low retention rate of breaking strength, with independent tests showing retention rates ranging from 62% to 73%. Combined with... Figure 4The curve trajectory shows that the quality of the flocculent detached material collected after the unbuffered treatment group was relatively high. The sodium hypochlorite treatment solution prepared with deionized water was alkaline. Medical cotton is mainly composed of natural cellulose polymers. In an alkaline liquid environment, the glycosidic bonds of the cellulose molecular chains undergo hydrolysis. Alkaline hydrolysis leads to the breakage of cellulose molecular chains, causing a decrease in the mechanical strength of the cotton and the production of structural detachment. The degradation of mechanical properties is caused by the physical structural damage induced by the alkaline solution environment, interfering with the assessment of the material's true resistance to chlorine oxidation.

[0142] Figure 3 Test data from the medium buffer group showed that the breaking strength retention rate of the cotton test pieces remained between 89% and 92%. Figure 4 Data shows that the shedding quality of flocculent material in the buffer group was controlled at a low level. The buffer group used a phosphate system to lock the pH of the treatment solution at a neutral state. The neutral environment inhibited the alkaline hydrolysis reaction of cellulose by hydroxide ions. The decrease in tensile strength of the test pieces in the neutral environment was due to the oxidative effect of free hypochlorous acid on the fiber structure and the fluid friction loss during liquid phase treatment. The comparison of the two sets of test results confirmed that controlling the treatment solution to a neutral state eliminated the structural damage interference caused by alkaline hydrolysis, allowing the physical and mechanical properties to purely reflect the material's performance in resisting effective chlorine oxidation.

[0143] Test Example 3: Test of the Calibration Ability of Dual-Track Blank Titration to Volatilization Error

[0144] Five quaternary ammonium salt modified medical cotton test pieces with a size of 5.0cm×5.0cm were cut and placed in a constant temperature and humidity chamber. The temperature was set at 23℃ and the relative humidity at 50%RH for 24 hours. The weight of each test piece was recorded as 2.00g.

[0145] The sodium hypochlorite stock solution was diluted with 0.1 mol / L phosphate buffer to prepare a treatment solution with an initial available chlorine concentration of 500 mg / L and a pH locked at 7.0. Multiple 200.0 mL portions of the treatment solution were measured and placed in the test group container and the blank group container, respectively.

[0146] Immerse the equilibrated test piece in the treatment solution of the test group container, while keeping the blank group container without a test piece. Simultaneously place the test group container and the blank group container in a constant temperature chamber at 37℃ and let them stand in the dark for 30 minutes.

[0147] After the settling process is completed, the test pieces in the test group container are quickly separated from the residual treatment liquid. The test residual liquid in the test group container and the blank residual liquid in the blank group container are then sealed and collected separately.

[0148] Take 25.0 mL of the test residue and blank residue respectively and place them in separate iodine flasks. Add 10 mL of 10 wt% potassium iodide solution and 15 mL of 1.0 mol / L sulfuric acid solution to each iodine flask and react in the dark for 5 min.

[0149] A 0.015 mol / L sodium thiosulfate standard titration solution was used to titrate the test residue and the blank residue. Near the endpoint, 1.0 wt% starch indicator was added, and titration continued until the blue color disappeared. The volumes of the test residue and the blank residue consumed were recorded. The theoretical titration volume corresponding to 25.0 mL of the initial treatment solution was calculated. Using the blank residue consumption volume and the theoretical titration volume as references, the net effective chlorine consumption for dual-track blank calibration and the uncalibrated effective chlorine consumption were calculated.

[0150] Table 3. Objective Quantitative Data Table of Dual-Track Blank Titration Calibration Verification Test

[0151] Sample number Theoretical titration volume (mL) Blank residual liquid consumption volume (mL) Test residual liquid consumption volume (mL) Uncalibrated available chlorine consumption (mg / g) Dual-track calibration of net available chlorine consumption (mg / g) 1 23.50 22.45 21.24 4.81 2.57 2 23.50 22.61 21.41 4.45 2.55 3 23.50 22.52 21.29 4.70 2.62 4 23.50 23.38 21.15 5.00 2.62 5 23.50 22.59 21.46 4.34 2.40

[0152] according to Figure 5 The displayed bar chart data shows that uncalibrated available chlorine consumption values ​​range from 4.34 mg / g to 5.00 mg / g, while dual-track calibrated net available chlorine consumption values ​​range from 2.40 mg / g to 2.62 mg / g. Combined with... Figure 6 The displayed curve shows that the theoretical titration volume is constant at 23.50 mL, the volume of blank residual liquid consumed is distributed between 22.45 mL and 23.38 mL, and the volume of test residual liquid consumed is distributed between 21.15 mL and 21.46 mL.

[0153] Sodium hypochlorite aqueous solution underwent a free chlorine volatilization and decomposition reaction in a constant-temperature heating environment. After standing for 30 minutes, the volume of the collected blank residual solution was lower than the initially calculated theoretical titration volume. The uncalibrated calculation method assumed that the initially added available chlorine did not undergo natural loss during the treatment stage, and directly included the physical loss of free hypochlorous acid in the environment into the chemical reaction consumption of medical cotton and available chlorine, resulting in an overestimation of the calculated consumption value and the introduction of systematic errors.

[0154] The dual-track blank titration procedure introduces a simultaneously heated and allowed-to-remain blank residue as a dynamic comparison benchmark, pre-emptively offsetting the volume difference caused by natural evaporation due to accumulated temperature and time. The net available chlorine consumption after dual-track calibration accurately reflects the chlorine equivalent consumed by the chemically modified layer on the cotton surface. By deducting the volume of natural loss due to environmental background, misdiagnosis of unreacted cotton samples as chemically inactive due to natural loss of available chlorine is avoided, ensuring the quantitative accuracy of the test data across different batches under different environmental conditions.

[0155] Test Example 4: Impact of Standardized Dry Locking on Data Accuracy (RSD)

[0156] Twenty quaternary ammonium salt modified medical cotton test pieces, each measuring 5.0cm × 5.0cm, were cut and placed in a constant temperature and humidity chamber. The chamber was set to 23℃ and 50%RH for 24 hours to maintain equilibrium. The test pieces were then randomly divided into a standardized drying group and a non-standardized drying group, with 10 test pieces in each group.

[0157] The sodium hypochlorite stock solution was diluted with 0.1 mol / L phosphate buffer to prepare a treatment solution with an initial available chlorine concentration of 500 mg / L and a pH locked at 7.0. Both sets of test pieces were completely immersed in the treatment solution, with the ratio of test piece mass to solution volume controlled at 1:100 g / mL. They were then simultaneously placed in a 37℃ incubator in the dark for 30 minutes.

[0158] After the treatment time is over, take out the test pieces and rinse them quickly three times in deionized water. Use filter paper to absorb the surface moisture for dehydration.

[0159] The standardized drying group test pieces were placed in a standard environment at 23°C and 50% RH for forced drying for 4 hours. The non-standardized drying group test pieces did not undergo the same environmental equilibration and forced drying steps.

[0160] Two groups of test pieces were tested simultaneously. A constant-rate elongation tensile testing machine was used to obtain the longitudinal breaking strength. Staphylococcus aureus was used as the experimental bacterial strain for shaking contact culture and plate counting. The breaking strength retention rate and antibacterial rate attenuation rate of 10 independent samples in each group were compared and calculated, and the relative standard deviation (RSD) of the two groups of data was calculated.

[0161] Table 4. Objective Quantitative Data Table for Verifying the Accuracy of Test Data by the Drying and Locking Step

[0162] Test group Sample number Fracture strength retention rate (%) Antibacterial rate attenuation rate (%) Standardized drying group Test 1 91.24 4.12 Standardized drying group Test 2 89.85 3.84 Standardized drying group Test 3 92.51 4.56 Standardized drying group Test 4 90.16 3.91 Standardized drying group Test 5 91.73 4.25 Standardized drying group Test 6 88.92 4.68 Standardized drying group Test 7 90.47 3.75 Standardized drying group Test 8 92.10 4.03 Standardized drying group Test Nine 89.55 4.41 Standardized drying group Test 10 91.08 3.52 Non-standardized drying group Test 1 75.42 1.58 Non-standardized drying group Test 2 98.21 12.45 Non-standardized drying group Test 3 62.15 6.82 Non-standardized drying group Test 4 85.67 18.26 Non-standardized drying group Test 5 71.34 3.14 Non-standardized drying group Test 6 102.56 9.67 Non-standardized drying group Test 7 68.91 22.51 Non-standardized drying group Test 8 89.43 4.75 Non-standardized drying group Test Nine 55.88 15.33 Non-standardized drying group Test 10 94.12 8.02 Standardized Drying Group RSD - 1.26% 8.55% Unstandardized drying group RSD - 18.73% 64.21%

[0163] (The "-" in the table indicates that it is not applicable or there is no corresponding separate number)

[0164] according to Figure 7 The displayed bar chart data shows that the relative standard deviations of the retention rate of breaking strength and the attenuation rate of antibacterial activity in the unstandardized drying group are 18.73% and 64.21%, respectively. The relative standard deviations in the standardized drying group decrease to 1.26% and 8.55%, respectively. Combined with... Figure 8 The displayed independent test curves show that the unstandardized drying group exhibited fluctuations in the tensile strength retention rate across ten consecutive independent tests, ranging from 55.88% to 102.56%. The standardized drying group, on the other hand, showed a more stable curve, with values ​​ranging from 88.92% to 92.51%.

[0165] Medical cotton's cellulose macromolecules possess hygroscopic properties. After liquid-phase exposure, unevenly distributed moisture remains inside the sample. The degree of swelling and tensile behavior of natural cotton fibers differ at different moisture contents, and this uneven moisture content causes random fluctuations in the breaking strength during tensile testing. Trace amounts of residual moisture carry unremoved free hypochlorous acid. Without forced drying, free chlorine undergoes uncontrolled oxidative degradation with the chemically modified layer on the cotton surface. The time difference between sample removal and testing completion translates into differences in reaction depth, causing the antibacterial rate index to lose reproducibility. The relative standard deviation of continuous testing exceeds the judgment range, rendering the data unusable as input for the failure attribution matrix.

[0166] The rinsing, dehydration, and drying steps removed the moisture trapped in the test pieces. The evaporation of ambient moisture physically unified the mechanical testing baseline state of the cotton fibers across the samples; chemically, it blocked the reaction medium, terminating the tailing oxidation reaction initiated by trace amounts of chlorine. Comparative testing data confirmed that the standardized drying and locking steps eliminated random state errors caused by internal moisture and residual reactants, limiting the dispersion of physical and chemical performance test data to a low range, and providing reproducible baseline data for the judgment rules.

Claims

1. A quality testing method for antibacterial and chlorine-resistant medical cotton, characterized in that, Includes the following steps: Select the test sample and the original sample, weigh the total mass of the test sample and balance it to obtain the balanced sample; Prepare the treatment solution, and take two equal volumes of the treatment solution as the test group solution and the blank group solution, respectively. The equilibrated test piece is immersed in the test group solution, while the blank group solution remains without test pieces and is simultaneously placed in the dark. After treatment, the equilibrated test piece and the test group solution are separated into solid and liquid components to obtain the separated test piece and residual treatment solution. The residual treatment solution and the blank group solution are respectively referred to as test residual solution and blank residual solution. The separated test pieces are rinsed, dehydrated, and dried to obtain dried test pieces; The dried test piece and the original test piece were simultaneously tested to obtain the longitudinal tensile strength and antibacterial rate, respectively. Take equal volumes of the blank residual liquid and the test residual liquid, respectively, and titrate them with standard titration solution. Calculate the net effective chlorine consumption based on the total mass of the test sample piece. By comparing the longitudinal tensile strength and antibacterial rate of the dried test piece and the original test piece, the tensile strength retention rate and antibacterial rate decay rate are calculated. The tensile strength retention rate, the antibacterial rate decay rate, and the effective chlorine net consumption are then substituted into the failure attribution matrix and compared with the pre-set threshold values ​​of each corresponding indicator.

2. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, When preparing the treatment solution, dilute the sodium hypochlorite stock solution with a phosphate buffer solution of 0.05-0.2 mol / L to prepare a solution with an initial available chlorine concentration of 450-550 mg / L and a pH of 6.5-7.

5.

3. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, When the balanced test piece is immersed in the test group solution, the ratio of the total mass of the test sample to the volume of the solution is controlled to be 1:50-1:200 g / mL; The conditions for synchronous light-protected static placement are: temperature set at 35-40℃, time set at 20-60min.

4. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, Before titrating with the standard titrant, take equal volumes of the blank residue and the test residue and place them in iodine flasks respectively. Add potassium iodide solution and sulfuric acid solution to each of the two iodine flasks. After reacting in the dark, add starch indicator and perform titration. The standard titrant is sodium thiosulfate standard titrant.

5. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 4, characterized in that, The specific logic for calculating the net consumption of available chlorine is as follows: The difference is obtained by subtracting the volume of the standard titration solution consumed by the blank residual solution from the volume of the standard titration solution consumed by the test residual solution. The difference is then multiplied by the concentration of the sodium thiosulfate standard titration solution, the chlorine molar mass constant, and the initial total volume of the treatment solution. The product is then divided by the sampling volume and finally by the total mass of the test sample to obtain the net effective chlorine consumption.

6. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, The determination rules for the failure attribution matrix include: The preset threshold values ​​for each corresponding indicator include the antibacterial rate attenuation threshold and the tensile strength retention threshold. The antibacterial rate attenuation threshold is set to 5%-10%, and the tensile strength retention threshold is set to 80%-90%. When the measured antibacterial rate attenuation rate is less than or equal to the attenuation threshold, and the tensile strength retention rate is greater than or equal to the retention threshold, the sample is deemed to have qualified antibacterial and chlorine-resistant properties.

7. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 6, characterized in that, The determination rules also include: When the measured tensile strength retention rate is greater than or equal to the retention threshold, but the antibacterial rate decay rate is greater than the decay threshold, and the effective chlorine net consumption is greater than 6.5 mg / g, it is determined that a chemical inactivation-dominated failure has occurred. When the measured antibacterial rate attenuation rate is less than or equal to the attenuation threshold, but the tensile strength retention rate is less than the retention threshold, and the effective chlorine net consumption is less than or equal to 1.5 mg / g, it is determined that a physical structure-dominated failure has occurred.

8. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, When weighing the total mass of the test sample and balancing, place the sample in a constant temperature and humidity chamber, set the temperature to 20-25℃ and the relative humidity to 60%-70%, and continue balancing for 24-48 hours. When synchronously avoiding light and allowing the material to stand still, a constant temperature chamber is selected as the standing equipment, and a black rubber light shield is added to the outside of the constant temperature chamber to block the light source.

9. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, The steps of rinsing, dehydrating, and drying are as follows: The separated test pieces were rinsed in deionized water, the surface moisture was absorbed with filter paper, and then forced to dry in a standard environment with a temperature of 20-25℃ and a relative humidity of 45%-55%RH for 3-6 hours. During the testing, a constant-rate elongation tensile testing machine was used to obtain the longitudinal breaking strength, and Staphylococcus aureus was used as the experimental strain for shaking contact culture and plate counting to obtain the antibacterial rate.

10. The quality testing method for antibacterial and chlorine-resistant medical cotton according to claim 1, characterized in that, The test sample and the original sample are modified medical cotton prepared in advance through the following processes: Immerse 100 parts by weight of medical degreased cotton fibers completely in an alkaline solution containing 2-8 parts by weight of sodium hydroxide, control the system bath ratio to be 1:20-1:50 g / mL, and perform alkalization pretreatment at a temperature of 40-60℃ for 30-60 min. After pretreatment, add 5-20 parts by weight of 3-chloro-2-hydroxypropyltrimethylammonium chloride solution to the system, and heat the system to 65-85℃ for isothermal etherification grafting reaction for 2-4 hours; After the reaction was completed, the system was neutralized to neutral with acetic acid solution. The reaction product was washed until the conductivity of the eluent remained constant. The reaction product was dried at 60-80℃ to constant weight to obtain quaternary ammonium salt modified medical cotton, which was then divided into test sample pieces and original sample pieces.

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