Surgical drape backing material and method of making

Abstract

The application discloses a surgical drape backing pile material and a preparation method thereof, and belongs to the technical field of medical textile materials. The pile material is divided into a tip end opening fiber section and an anchoring section at the root along the axial direction of the pile material. In the opening fiber section, the sea component is removed and the island component is separated into superfine filaments. In the anchoring section, the sea component is retained and the island component is still covered. The anchoring section continuously extends to the embedded section of the pile in the base cloth. The length of the opening fiber section and the exposed height of the pile are in a ratio of 0.68 to 0.78. During the preparation, the pile is raised first and then the amount is reduced. The tip end of the pile is contacted with an alkali solution layer with controlled thickness. The alkali solution is made to climb along the capillary of the pile through steaming. Then, the opening fiber depth is converted into two adjustable quantities of the gap of the scraper and the linear velocity by neutralizing and cutting off the reaction in the acid bath according to the time. The application can prevent the falling of the pile from being deteriorated with the number of washing times, and does not depend on resin immersion.

Description

Technical Field

[0001] This invention relates to the field of medical textile materials technology, specifically to a surgical drape lining material and its preparation method. Background Technology

[0002] Surgical drapes are medical textiles used during surgery to cover the patient's body, instrument table, and surrounding areas to establish and maintain a sterile barrier. Near the incision, surgical drapes typically have a lining layer to absorb blood and irrigation fluid, preventing fluid buildup and flow that could create a fluid pathway. Microfiber fleece material, due to its extremely fine fibers, large specific surface area, high capillary pressure, soft feel, and washability, is theoretically well-suited for this lining function. However, this type of material has not yet been practically used in surgical drapes for the following reasons.

[0003] Firstly, the requirement for lint shedding in medical surgical drapes is not that they must be qualified as new products, but rather that they must be qualified throughout their entire lifespan. According to the current standards for medical surgical drapes, gowns, and cleanroom garments, the lint shedding coefficient of surgical drapes is determined using a dry-state lint shedding test method, and its commonly used logarithmic value must not exceed 4.0. Furthermore, this requirement, like other performance requirements, must be continuously met throughout the product's entire lifespan. Reusable surgical drapes are typically rated by manufacturers for a lifespan of 75 to 100 washes, with actual measurements in industrial washing environments showing approximately 60 washes. In other words, even if a lining material passes new product testing, if its lint shedding continuously deteriorates with each wash and exceeds the limit midway through its lifespan, the material is still considered unqualified according to the standards.

[0004] Secondly, the entry of lint into surgical wounds poses clear clinical risks. Clinical literature reports that lint from surgical drapes can cause thrombosis, worsen infection and biofilm formation, amplify inflammation, reduce healing quality, lead to foreign body granulomas, and cause postoperative adhesions. One five-year report from three hospitals documented 24 cases of foreign body reactions caused by lint from paper-based surgical drapes, including 6 cases that progressed to severe acute granulomatous peritonitis (1 death), and 22 cases requiring reoperation, resulting in approximately 400 additional hospital stays. Therefore, lint in surgical drapes is not tolerated.

[0005] Thirdly, the alkali reduction fiber opening process, essential for achieving the ultra-fine feel of island-type microfiber nap, itself causes the nap to loosen. Island-type composite filaments consist of island components and sea components covering the island components. The role of alkali reduction is to dissolve the sea components, causing the island components to disperse into separate ultra-fine monofilaments. This process is clearly documented in the relevant technical literature: during the process of extracting the sea components to refine the fibers, gaps naturally form between the microfiber bundle and the surrounding matrix, increasing the freedom of movement of the microfiber bundle. In other words, while giving the material an ultra-fine feel, fiber opening inevitably leaves radial gaps between the fibers and the yarn channels they occupy, thus providing the fibers with channels for axial sliding within the channels.

[0006] Fourth, existing alkali reduction processes are all integral impregnation methods, with the reduction step preceding the napping process. As a result, the entire length of the pile, including the portion embedded in the base fabric, is broken down, leaving no unbroken anchored sections in the material. Existing processes only provide four reduction parameters: concentration, temperature, time, and reduction rate. Some schemes use a sodium hydroxide concentration of 8-12 g / L, a temperature of 85-95 degrees Celsius, and a time of 20-40 minutes, with the process involving alkali reduction, dyeing, finishing, and finally napping and brushing. Other schemes use a concentration of 12-18 g / L, a temperature of 110 degrees Celsius, a time of 60 minutes, and a reduction rate of 15%-25%, with the process involving alkali reduction and fiber breaking, polyurethane impregnation, drying and setting, brushing, and dyeing. It is clear that existing technologies are always concerned with the extent of reduction, but never with the depth of the reduction effect, i.e., the spatial distribution of the reduction along the pile axis. The reason is understandable: in the existing product system, fiber opening is just a background process that can be done properly, and the technological contribution is generally placed on yarn structure, fabric structure and resin formulation.

[0007] Fifth, the conventional approach to controlling lint shedding in this field is polyurethane or resin impregnation and fixation. This involves impregnating the material with polyurethane before and after fiber splitting, relying on the resin to bond the fibers to the matrix. This approach is almost standard in suede-like materials. However, it comes at a significant cost: actual measurements show that as the amount of polyurethane impregnation increases, the air permeability of the base fabric decreases from 50,086 ml / m² / s to 24,757 ml / m² / s, a decrease of approximately 50.6%; the water vapor permeability decreases from 790.47 mg / 10 cm² / 24 hours to 488.70 mg / 10 cm² / 24 hours, a decrease of approximately 38.2%. For surgical drapes and linings that need to absorb liquids while maintaining breathability, such a cost is unacceptable. More importantly, the resin membrane ages and cracks during repeated industrial washing and high-temperature sterilization cycles. On the one hand, it gradually loses its fixing effect; on the other hand, the cracking itself produces polymer debris, causing the amount of particulate matter from the lint to increase rather than decrease.

[0008] Therefore, there is a need in the field for a surgical liner lining material and its preparation method that can maintain the feel and liquid absorption properties of the microfiber velvet surface, prevent lint shedding from deteriorating with the number of washes, and is not dependent on resin impregnation. Summary of the Invention

[0009] The technical problem this invention aims to solve is that the lint shedding of microfiber fleece materials from islands deteriorates monotonously with each wash, making it impossible to continuously meet the lint shedding limit within the nominal service life of reusable surgical sheets; while alkali reduction fiber opening imparts an ultra-fine feel, it inevitably loosens the fleece within the base fabric, creating a contradiction; conventional countermeasures in the field for controlling fleece shedding, namely resin impregnation and fixation, significantly impair breathability and liquid absorption performance, and the fixation effect is lost and new particles are generated after the resin ages and cracks.

[0010] The technical concept of this invention is based on a renewed understanding of the process of fluff removal. Fluff removal is not a one-time static pull-out, but a cumulative damage process: when there is a radial gap left by the dissolution of marine components between the fiber and the yarn channel it occupies, each washing and friction cycle causes a small amount of fluff to slide out within the channel, and its embedment length gradually shortens; the shortening of the embedment length reduces the anchoring force, thus accelerating the slippage until the embedment length is exhausted and the fluff falls off. Conversely, when the section where the fiber is located still retains marine components, and the island components are still covered by marine components and tightly filled with the channels, the slippage channel does not exist from the beginning, and the fiber is held and locked by the matrix. This yields a previously unused degree of freedom: what determines whether fluff can remain on the base fabric for a long time is not the degree of alkali reduction, but the depth of the alkali reduction effect.

[0011] Accordingly, this invention transforms alkali reduction from a degree variable to a depth variable: first, the pile is raised, then the reduction is performed, and the alkali solution only acts on a limited depth measured from the tip of the pile, thereby creating two functionally different sections on the same pile. The open fiber section at the tip is responsible for providing an ultra-fine feel, capillary suction pressure, and liquid absorption capacity; the anchoring section at the root retains the unopened island composite structure, and together with the embedded section where the pile is embedded in the base fabric, it is responsible for firmly keeping the pile on the base fabric.

[0012] Most importantly, the direction of this invention is opposite to that of the prior art. Prior art, whether the applicant's earlier solution or those of competitors, pursues full, uniform, and complete fiber opening, with reduction times ranging from twenty to sixty minutes, and the reduction is always arranged before napping. This invention, however, requires spatially interrupting the reduction process, ensuring it only acts on the tips of the fibers, and moving the reduction process after napping. Both modifications are indispensable: simply changing the process order without limiting the reduction depth will still allow the alkali solution to penetrate the fabric and open the fibers into the base fabric; limiting the depth while still prioritizing reduction before napping will result in napping being performed on fibers that have already been fully opened, making it impossible to form an anchoring section.

[0013] The specific means by which this invention achieves this depth control is through a combined control of coarse adjustment based on thickness and fine adjustment based on time. The alkali solution, in a layer with controlled thickness, contacts the upright tips of the fibers. The thickness d of this layer determines the length of the fibers directly immersed by the alkali solution, which is the coarse adjustment amount. After contact, the alkali solution continues to climb from the tip to the root along the capillary channels of the fiber bundle. The climbing length L1 increases with time according to the square root law, which is the fine adjustment amount. At the moment the climbing reaches the predetermined depth, the alkali reduction reaction is spatially interrupted by neutralization in an acid bath. The axial length h1 of the fiber opening segment is therefore equal to the sum of the two, that is, h1 equals the thickness d plus the climbing length L1, and L1 equals the climbing coefficient k multiplied by the square root of time t. This relationship transforms a spatial quantity that is difficult to measure directly, namely the fiber opening depth, into two process quantities that are directly adjustable on the production line: the doctor blade gap and the fabric linear speed.

[0014] To solve the above-mentioned technical problems, the present invention provides a surgical liner material with a felted surface and a method for preparing the same.

[0015] The surgical liner material provided by this invention includes a base fabric layer and a pile layer fixed to one side of the base fabric layer. The pile layer is composed of pile formed from island-island composite filaments. The pile is divided into an open fiber section and an anchoring section along its own axial direction from the tip to the root. In the open fiber section, the sea component has been removed and the island component is in the form of separate ultrafine monofilaments. In the anchoring section, the sea component is retained and the island component is still covered by the sea component and is in the form of composite filaments. The anchoring section extends continuously from the root of the pile and passes through the surface of the base fabric layer into the embedded section where the pile is embedded in the base fabric layer, so that the entire length of the embedded section is in the state of retaining the sea component. The ratio R of the axial length h1 of the open fiber section to the height h0 of the pile exposed on the surface of the base fabric layer is not less than 0.68 and not greater than 0.78, and the axial length of the portion of the anchoring section above the surface of the base fabric layer is not less than 0.15 mm.

[0016] The present invention also provides a method for preparing the above-mentioned surgical liner lining material, comprising: S1, weaving a base fabric using island-island composite filament as the pile yarn to obtain a grey fabric; S2, after scouring and pre-forming, pile is raised and sheared so that the exposed pile height h0 is 0.6 to 1.2 mm, at which time the island-island composite filament has not yet been opened; S3, applying alkali to the tip of the pile layer so that the tip of the pile layer is in contact with an alkali solution layer of thickness d while the base fabric layer is not in contact with the alkali solution; S4, steaming and stacking for time t, so that the alkali solution climbs capillarily along the pile axis for a length L1; S5, timing neutralization and cutting so that the axial length h1 of the opened fiber section is equal to the sum of d and L1 and the ratio R falls between 0.68 and 0.78; S6, washing, drying and post-setting; S7, coating with a microporous polyurethane liquid-resistant layer.

[0017] Furthermore, the exposed pile height h0 is 0.6 to 1.2 mm, the monofilament linear density of the island-island composite filament is 0.3 to 0.6 dtex, the number of islands is 25 to 40, the sea component mass fraction is 25% to 35%, and the linear density of the ultrafine monofilament in the open fiber section is not greater than 0.02 dtex; a microporous polyurethane liquid-resistant layer is provided on the side of the base fabric layer facing away from the pile layer, and the water resistance of the pile material is not less than 30 cm water column; the overall alkali reduction rate of the pile material is 3% to 9%, significantly lower than the reduction rate when the pile is opened along its entire length. The set value of time t is equal to the difference between the target fiber opening length and the thickness d, divided by the creep coefficient k, and the square of the quotient. The actual time t is made to reach the set value by adjusting the fabric linear speed v. The alkali is applied to the tip by a liquid supply roller immersed in the alkali tank at the bottom, in conjunction with a scraper attached to its surface. The thickness d of the alkali layer is determined by the gap between the scraper and the liquid supply roller. The longitudinal section of the pile can also be sampled on the finished product to measure the actual h1 based on the boundary position between the fiber opening section and the anchoring section, and the thickness d and time t are corrected in reverse.

[0018] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0019] First, lint shedding no longer worsens with the number of washes. Numerical simulations under the same model and criteria show that the lint shedding coefficient of the velvet material using this invention remains stable between 3.01 and 3.06 throughout the entire washing process from 0 to 120 washes, and basically does not change with the number of washes; while the control sample prepared according to the current soaking process exceeds the limit of 4.0 after 60 washes, and reaches 4.353 after 100 washes.

[0020] Second, the significantly extended wash life makes this type of material qualified for use as a reusable surgical drape liner for the first time. Simulation results show a wash life of 45.9 cycles with a standard deviation of 15.9 cycles for the current process, while this invention does not exceed the lint shedding limit even at the upper limit of 120 cycles. Even taking the upper bound of the expanded uncertainty of 59.5 cycles, the wash life of the current process is still significantly lower than the manufacturer's stated 75 to 100 cycles.

[0021] Third, it avoids the conventional approach and its associated costs of resin impregnation and fixation. This invention does not introduce any third component into the material, but achieves anchoring solely through the spatial selectivity of the alkali reduction process itself. Therefore, it does not impair air permeability and liquid absorption performance, nor does it address the issues of fixation failure and polymer debris generation after resin film aging and cracking.

[0022] Fourth, barrier properties are improved simultaneously. Due to the significant reduction in lint shedding, the number of through-holes formed inside the fabric due to lint shedding is correspondingly reduced. Simulation results show that after 100 washes, the water resistance of this invention is 47.8 cm water column with a standard deviation of 2.7 cm water column, which is higher than the current process's 37.6 cm water column with a standard deviation of 3.6 cm water column. Both of these are limited to a value of 30 cm water column.

[0023] Fifth, the two modifications constitute an inseparable technical whole. Simulated ablation tests show that when only the process sequence is retained without limiting the reduction depth, the lint shedding rate after 100 washes is 4.02, which exceeds the limit; when only the depth is limited but the reduction is still performed before linting, the rate is 4.34, which exceeds the limit even more; when both are met, the rate is 3.06, which is acceptable.

[0024] Sixth, the overall alkali reduction rate decreases, and the loss of fiber materials, as well as alkali and acid consumption, decrease accordingly. Since only the tip of the pile participates in the reduction, the overall reduction rate of this invention is 3% to 9%, while the current process of opening the entire length of the pile is usually 15% to 25%. Attached Figure Description

[0025] Figure 1 This is a schematic diagram of the cross-sectional structure of the velvet-textured lining material for surgical drapes according to an embodiment of the present invention;

[0026] Figure 2 This is a flowchart illustrating the preparation method of the velour fabric material for the surgical liner of this invention.

[0027] Figure 3 This is a schematic diagram of the station configuration for the tip-limited alkali application, steam climbing, and timed neutralization cutoff in an embodiment of the present invention;

[0028] Figure 4 This is a comparison diagram of the effects of an embodiment of the present invention. The upper part shows the evolution curves of the lint shedding coefficient with the number of washing cycles for three control groups, and the lower part shows the available window of the proportion R of open fiber segments. Detailed Implementation

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments. The following embodiments are for illustrative purposes only and are not intended to limit the scope of the invention. The fleece material described in this invention, in addition to being used as a lining layer for surgical drapes, is also suitable for reinforcing areas of surgical gowns, instrument table covers, and other reusable medical textile products with a full lifespan requirement for lint shedding.

[0030] I. Structure of suede materials

[0031] The cross-sectional structure of the fleece lining material of the surgical drape in this embodiment is as follows: Figure 1 As shown, it includes a base fabric layer 1 and a pile layer 2 fixed to one side of the base fabric layer 1. The pile layer 2 is composed of several piles 3, which are formed from island composite filaments.

[0032] The pile 3 is divided into an open fiber section 31 and an anchoring section 32 along its own axis from tip to root, and is embedded in the base fabric layer 1 by an embedded section 33. In the open fiber section 31, the sea component 6 has been removed, and the island component is in the form of separate ultrafine monofilaments 5. The ultrafine monofilaments 5 are no longer bonded to each other and can freely spread, bend and intertwine, which is why the pile surface has an ultrafine fiber feel and high capillary attraction pressure. In the anchoring section 32, the sea component 6 is retained, and the island component is still covered by the sea component 6 and is in a composite filament state, and its shape is consistent with the unreduced island-island composite filament.

[0033] The anchoring section 32 extends continuously from the root of the pile 3, passes through the surface of the base fabric layer 1, and enters the embedded section 33, ensuring that the entire length of the embedded section 33 retains the sea component 6. This is the core difference between this invention and the prior art: in pile materials produced by the current impregnation process, the embedded section 33 is also split, and the sea component 6 is dissolved inside the base fabric layer 1, leaving radial gaps between the fibers and the yarn channels they occupy; however, in this invention, the sea component 6 of the embedded section 33 is intact, the island component is filled with the sea component 6 and tightly adheres to the channels, and there are no radial gaps.

[0034] In this embodiment, the height h0 of the pile 3 protruding from the surface of the base fabric layer 1 is 0.85 mm, the axial length h1 of the open fiber segment 31 is 0.620 mm, and the ratio R between the two is 0.73; the axial length of the portion of the anchoring segment 32 above the surface of the base fabric layer 1 is 0.230 mm, which is not less than 0.15 mm. The selectable range of h0 is 0.6 to 1.2 mm, and the selectable range of R is 0.68 to 0.78. The basis for the upper and lower limits is explained in Section 3 below.

[0035] The island-island composite filament used in this embodiment is a finished yarn with a specification of 288 strands at 105 denier and an island-island ratio of 30:70. Based on this, the linear density of the single filament is approximately 0.405 dtex, and each composite filament contains 37 island components and a sea component mass fraction of 30%. Calculated based on polyester density, the equivalent diameter of the composite filament is approximately 6.11 micrometers; the linear density of a single ultrafine monofilament 5 after fiber opening is approximately 0.0077 dtex, and the equivalent diameter is approximately 0.841 micrometers. The selectable range for the island-island composite filament is a single filament linear density of 0.3 to 0.6 dtex, 25 to 40 islands, and a sea component mass fraction of 25% to 35%. The linear density of the ultrafine monofilament 5 in the fiber-opening section 31 is not greater than 0.02 dtex.

[0036] A microporous polyurethane liquid-resistant layer 4 is provided on the side of the base fabric layer 1 facing away from the fleece layer 2. The liquid-resistant layer 4 serves as a barrier layer for the surgical drape, preventing liquid from penetrating to the back of the drape after being absorbed by the fleece layer 2. In this embodiment, the fleece material has a water resistance of not less than 30 cm of water column.

[0037] Since only the tips of the fibers 3 participate in alkali reduction, the overall alkali reduction rate of the pile material in this embodiment is 3% to 9%, which is significantly lower than the 15% to 25% typically achieved when the entire length of the pile is opened. This difference can serve as an auxiliary feature for identifying the product of the present invention: under the same fiber specifications and pile morphology, the reduction rate of the product of the present invention is significantly lower, while the ultra-fine feel of the pile is not inferior, because the feel depends only on the section of the pile surface that has been opened.

[0038] II. Preparation Method

[0039] The preparation method flow of this embodiment is as follows: Figure 2 As shown, the workstation configuration is as follows: Figure 3 As shown, it includes the following steps.

[0040] S1. Weaving. The base fabric is woven using island-island composite filaments as the napping yarn to obtain the grey fabric. This embodiment employs a warp-knitted structure, with elastic fibers incorporated into the warp yarns to give the material a conforming ability; a woven satin structure can also be used. During weaving, loops or long floats are formed on one side of the fabric according to the subsequent napping requirements.

[0041] S2. Raising and Shearing. The greige fabric is scouring and pre-shaped, and then a multi-roller raising machine is used to raise one side of the greige fabric, pulling out and breaking the loops or long floats to form pile 3. Then, the pile 3 is sheared by a fixed-height shearing mechanism 14, so that the height h0 of the pile 3 exposed on the surface of the base fabric layer 1 reaches 0.85 mm, and the coefficient of variation of h0 is not greater than 0.15.

[0042] It is important to emphasize that, up to this step, the island-island composite filaments in the pile 3 have not yet been opened and remain a complete island-island composite structure. This is the opposite of the current process sequence: the current process involves first alkali reduction and opening, then pile formation and brushing, with pile formation acting on the already fully opened microfibers. This invention moves the alkali reduction process entirely after pile formation, which is a prerequisite for forming the anchoring section 32. This is because only when pile formation is completed before the fibers are opened can the subsequent restricted reduction selectively open only the fiber tips.

[0043] S3. Limited Alkali Application at the Tip: The tips of the pile layer 2 are brought into contact with the alkali solution layer, while the base fabric layer 1 remains uncontacted. This embodiment utilizes a feed roller 7: the lower part of the feed roller 7 is immersed in the alkali solution tank 8, and the doctor blade 9 rests against the surface of the feed roller 7. The thickness d of the alkali solution layer carried out is determined by the gap between the doctor blade 9 and the feed roller 7. The fabric 13, with the pile layer 2 facing downwards, is guided by the guide roller 12 and passes over the feed roller 7, with the tips of the pile 3 immersed in the alkali solution layer on the surface of the feed roller 7. The running tension of the fabric 13 is maintained within a range that keeps the pile 3 upright and prevents it from being crushed by the feed roller 7, ensuring that the immersion depth is consistent with the thickness d of the alkali solution layer.

[0044] In this embodiment, the thickness d is set to 0.55 to 0.70 times h0, and is set to 0.62 times, i.e., 0.62 multiplied by 0.85 mm equals 0.527 mm, which is directly given by the gap adjustment mechanism of the doctor blade 9. The alkali solution is a sodium hydroxide solution with a concentration of 40 to 80 grams per liter. Compared with the low concentration and long preparation time of 8 to 18 grams per liter used in the current whole-immersion process, this invention uses a higher concentration and a very short preparation time. The purpose is to limit the reaction spatially to the area that the alkali solution can reach, rather than relying on the accumulation of time to make the reaction spread throughout the entire fabric.

[0045] S4. Steaming and Capillary Climbing. The fabric 13 from S3 enters the steaming chamber 10, where it is steamed at 100 to 120 degrees Celsius and piled for time t. During this period, the alkali solution climbs along the axial direction of the fibers 3 from the tip to the root capillary. The climbing length L1 increases with time according to the square root law, that is, L1 is equal to the climbing coefficient k multiplied by the square root of time t. The climbing coefficient k is determined by the surface tension and viscosity of the alkali solution and the equivalent capillary radius of the fiber bundle according to the capillary penetration relationship. For a given fiber specification and alkali solution formula, k can be directly calibrated by pre-test: samples are taken at several different piling times, and the boundary position between the open fiber section 31 and the anchoring section 32 on the longitudinal section of the fibers 3 is measured. A linear regression is performed on the climbing length L1 against the square root of time t, and the slope obtained is k. In this embodiment, the calibrated k is approximately 0.0139 mm per half-second.

[0046] S5. Timing Neutralization Cutoff. Timing begins when the alkaline solution in S3 comes into contact with the tips of the fibers 3. When time t reaches the set value, the fabric 13 is placed in the acid bath 11. The pH of the acid bath is 4 to 5, which spatially cuts off the alkali reduction reaction. The set value is calculated as follows: first, multiply the ratio R by the height h0 to obtain the target fiber opening length, then subtract the thickness d to obtain the length that needs to be supplemented by capillary climbing, divide by the climbing coefficient k, and take the square, which is the set value of time t. In this embodiment, R is 0.73, the target fiber opening length is 0.620 mm, and the length that needs to be supplemented by climbing is 0.620 minus 0.527 equals 0.093 mm. Divide by 0.0139 and take the square, which gives time t as approximately 45 seconds.

[0047] The execution point of time t is the linear velocity of the fabric. The distance between the inlet of the acid bath 11 and the outlet of the steam box 10 is L, and the linear velocity of the fabric is v. Taking into account the conveying time t0 between S3 and S4, the actual time t is equal to t0 plus L divided by v. In production, the actual time t is brought to the set value by adjusting the linear velocity v. In this way, a spatial quantity, namely the fiber opening depth, is completely converted into two quantities that are directly adjustable on the two production lines: the gap of the doctor blade 9 is given by the thickness d, and the fabric linear velocity v is given by the time t.

[0048] S6. Washing, drying and post-setting. The fabric 13, which has been neutralized by acid bath, is thoroughly washed to remove residual alkali and reaction products, and then dried and post-set.

[0049] S7. Coating the liquid-blocking layer. Microporous polyurethane is coated on the side of the base fabric layer 1 that is opposite to the pile layer 2 to form the liquid-blocking layer 4.

[0050] S8. Closed-loop calculation and correction. After S6, samples are taken from the finished product, and longitudinal sections of the pile 3 are cut and observed under a microscope. The actual axial length h1 of the open fiber section is calculated based on the distance from the boundary between the open fiber section 31 and the anchoring section 32 to the surface of the base fabric layer 1. The thickness d in S3 and the time t in S5 are corrected in reverse according to the deviation between the actual h1 and the target value. If the deviation is positive, i.e., the open fiber is too deep, the thickness d is reduced first; if the deviation is negative, i.e., the open fiber is too shallow, the time t is increased first. The reason for this arrangement is that the adjustment of the thickness d is instantaneous, while the adjustment of the time t changes the linear speed of the entire production line.

[0051] III. The Value Window of the Ratio R and its Basis

[0052] The upper and lower limits of the ratio R are given by two constraints with completely different mechanisms, which intersect to form a usable window, such as... Figure 4 The lower half is shown.

[0053] The lower limit is given by the liquid absorption capacity. The open fiber segment 31 is the region with the highest capillary pressure in the velvet material, and liquid is first drawn into this region. The thinner the open fiber segment 31, the less liquid it can hold per unit area. A single drop of liquid must spread laterally across a larger area on the material surface to be completely absorbed; and the lateral spreading time increases with the square of the spreading radius, thus rapidly lengthening the absorption time and increasing the risk of residual liquid film on the liner surface. Simulations show that when the ratio R is below 0.67, the time required to absorb 100 microliters of blood is more than 1.5 times that of the current process.

[0054] The upper limit is determined by the integrity of the base fabric. The limitation of this invention is achieved by controlling the penetration depth of the alkali solution, which fluctuates during production. The closer the ratio R is to 1, the shorter the anchoring section 32, and the easier it is for fluctuations in penetration depth to exceed the exposed height h0 of the pile 3 and directly affect the base fabric layer 1. Once the base fabric layer 1 is reduced by alkali, the fabric strength decreases linearly with the reduction rate, jeopardizing the requirements for burst strength and breaking strength. With the process quality target of the base fabric exceeding the limit damage area not exceeding 1%, simulation gives an upper limit of approximately 0.81 for the ratio R.

[0055] Taking both sides into account, the simulation gives an available window of R from 0.67 to 0.79, and the claims of the present invention take values ​​of 0.68 to 0.78 within this window. Accordingly, the axial length of the portion of the anchoring section 32 above the surface of the base fabric layer 1 is 0.187 to 0.272 mm in this embodiment when h0 equals 0.85 mm, and is therefore limited to not less than 0.15 mm.

[0056] IV. Effect Verification

[0057] The following data are numerical simulation results, not actual bench test values. The simulation was performed on a case constructed according to the model and criteria described below. The code and the source of all input parameters are archived and can be reproduced.

[0058] The key points of the simulation model are as follows: Filament shedding is modeled as a cumulative slip process: the anchoring force of a single filament is the product of the interfacial shear resistance and the fiber side surface area; after the sea element is dissolved, the fiber volume fraction decreases, and the interfacial normal pressure decreases according to the fiber aggregate compression law with a volume fraction cubed; in each friction cycle, filaments in the gapped section slip out by a small amount that has a power-law relationship with the applied force compared to the anchoring force. This slippage shortens the embedment length and further reduces the anchoring force, thus accelerating the slippage; filaments in the sea element-retained section experience an order-of-magnitude increase in slippage resistance. The penetration depth of the alkali solution is described by a normal distribution to account for its process fluctuations. The absorption time is calculated by combining capillary suction pressure and permeability to synthesize the longitudinal penetration and lateral spreading times. Each group is repeated 8 times, tracking 800 filaments each time. The random seed is derived from the baseline seed with an index, ensuring consistent results for reruns of the same example.

[0059] Three control groups were set up. Group A was the no-resin group, i.e., the current process, which involves first impregnating the entire pile with alkali to reduce the amount of fibers, and then raising the pile, with the entire length of the pile and the embedded section being opened together. Group B was the conventional method group, which, based on Group A, adds resin impregnation to fix the pile roots, which is the first reaction in the field to control pile loss. Group C was the present invention, which involves first raising the pile and then limiting the amount of fibers at the tip, with a ratio R of 0.73.

[0060] Usable washing life is defined as the number of washes a product can withstand before the commonly used logarithm of the lint coefficient first exceeds 4.0, with an upper limit of 120 washes. Group A, using the current process, achieved 45.9 washes (standard deviation 15.9); Group B, using the conventional method, achieved 31.0 washes (standard deviation 8.4); Group C, with the present invention, did not exceed the upper limit of 120 washes. The differences between Group C and Group A, and between Group C and Group B, were all statistically significant. It should be noted that the 120 washes for Group C is the upper limit of the assessment, not the actual measured lifespan.

[0061] The logarithmic value of the lint shedding coefficient after 100 washes is typically set at no more than 4.0: Group A: 4.353 (standard deviation 0.086, exceeding the limit); Group B: 4.417 (standard deviation 0.069, exceeding the limit); Group C: 3.063 (standard deviation 0.042, acceptable). The water resistance at the same point in time is set at a minimum of 30 cm of water column: Group A: 37.6 cm (standard deviation 3.6); Group B: 38.2 cm (standard deviation 3.6); Group C: 47.8 cm (standard deviation 2.7).

[0062] The evolution of the commonly used logarithmic value of the lint shedding coefficient with the number of washes is as follows: Figure 4 The upper half is shown. Group A, the current process, yields values ​​of 3.09, 3.24, 3.56, 3.91, 4.09, 4.24, 4.34, and 4.44 for 0, 10, 20, 40, 60, 80, 100, and 120 washes, respectively. Group B, the conventional method, yields values ​​of 3.09, 3.53, 3.82, 4.09, 4.23, 4.34, 4.40, and 4.48 for the same points. Group C, the present invention, yields values ​​of 3.03, 3.04, 3.06, 3.05, 3.05, 3.03, 3.06, and 3.01 for the same points.

[0063] The above evolution reveals a fact of practical significance in this field: the three groups showed almost no difference in their new state, with lint shedding coefficients all between 3.03 and 3.09; the differences only became apparent during the lifespan of the product. This indicates that selecting surgical liner materials solely based on new product indicators would lead to erroneous conclusions, which is one of the reasons why such materials have not been properly evaluated previously.

[0064] The results for Group B require specific explanation. The resin impregnation fixation used in Group B is a standard practice in this field; however, simulations show that it not only failed to solve the problem, but its usable wash life of 31.0 cycles was actually lower than Group A's 45.9 cycles (no action taken). The mechanism is clear: the resin, in its fresh state, does fill the gaps between the fibers and pores, thus suppressing the rise of lint in the first ten or so washes; however, the resin membrane ages and cracks during repeated washing and high-temperature sterilization, gradually losing its fixation effect, and the cracking itself generates polymer debris, causing the particulate matter content of the lint to increase rather than decrease. Simultaneously, according to the aforementioned experimental literature, polyurethane impregnation reduces air permeability by approximately 50.6% and water vapor permeability by approximately 38.2%; in this simulation, the time for Group B to absorb 100 microliters of blood worsened from 7.85 seconds in Group A to 14.00 seconds.

[0065] The ablation test is used to verify whether the two modifications of this invention can be separated, and is assessed up to 100 washes. When the invention is fully implemented (i.e., first raising the fibers and then limiting the reduction at the tip, with a ratio R of 0.73), the lint shedding coefficient is 3.06, which is acceptable, and the usable wash life is 120 washes. If only the process sequence is retained without limiting the reduction depth (i.e., a ratio R of 1.0), the lint shedding coefficient is 4.02, exceeding the limit, and the usable wash life drops to 73.2 washes. If only the depth is limited but the reduction is still done before raising the fibers (i.e., full soaking), the lint shedding coefficient is 4.34, exceeding the limit even more, and the usable wash life drops to 38.2 washes. It is evident that the two modifications of this invention are indispensable; they constitute an inseparable technical whole, rather than a simple superposition of features.

[0066] The window scan results for the ratio R are as follows, with each item assessed up to 100 washes. When R is 0.64, the exposed length of the anchoring section is 0.306 mm, the lint is 3.06 mm, the absorption time is 11.99 seconds, and the base fabric's cross-boundary damage area is 0.00%, indicating slow absorption. When R is 0.67, the exposed length of the anchoring section is 0.280 mm, the lint is 3.06 mm, the absorption time is 11.47 seconds, and the damage area is 0.00%, which is acceptable. When R is 0.73, the exposed length of the anchoring section is 0.230 mm, the lint is 3.06 mm, the absorption time is 10.56 seconds, and the damage area is 0.04%, which is acceptable. When R is 0.79, the exposed length of the anchoring section is 0.178 mm, the lint is 3.06 mm, the absorption time is 9.78 seconds, and the damage area is 0.43%, which is acceptable. When R is 0.82, the exposed length of the anchoring section is 0.153 mm, the lint is 3.06 mm, the absorption time is 9.44 seconds, and the damaged area is 1.22%, which is considered to be excessive damage to the base fabric. When R is 1.00, the exposed length of the anchoring section is zero, the lint is 4.02 mm, the absorption time is 7.85 seconds, and the damaged area is 50.00%, with both the lint and the base fabric damage exceeding the standard.

[0067] Regarding parameter sensitivity, several parameters in the model lack publicly available experimental data and are considered to be of a magnitude set to ensure model closure. To verify whether the conclusions depend on these settings, samples were taken from the upper and lower 50% ranges for each of the five parameters: slip scale, slip power, lock-in factor, applied force ratio, and penetration fluctuation, resulting in 448 parameter combinations that were re-run. The results show that the lint removal advantage of this invention compared to the current process is positive in all 448 combinations, with the advantage ranging from 0.13 to 2.75 log units, and the direction of the conclusion was not reversed even once. The parameter with the greatest impact is the scale of washing friction, with a first-order sensitivity index of 0.991.

[0068] Regarding uncertainty, using the simplified formula of the measurement uncertainty representation guideline and taking a coverage factor of 2, the lint shedding coefficient after 100 washes in this invention is 3.09, with an expanded uncertainty of 0.25 log units. The uncertainty is primarily determined by the model setting parameters, accounting for 87%. The usable washing life of the current process is 43.3 washes, with an expanded uncertainty of 16.2 washes. The uncertainty is primarily determined by repeatability, accounting for 96%. Even taking the upper limit of the expanded uncertainty of 59.5 washes, the lifespan of the current process is still significantly lower than the manufacturer's stated 75 to 100 washes.

[0069] The following adverse results are also recorded. First, the absorption time of the present invention is inferior to that of the current process: when the ratio R is 0.73, the present invention requires 10.56 seconds to absorb 100 microliters of blood, while the current process takes 7.85 seconds, which is about 34% slower. This is the price paid for retaining the anchoring section, because the open fiber section becomes thinner, and the liquid volume per unit area decreases accordingly; the present invention therefore limits the lower limit of the ratio R to 0.68, so that the absorption time is not inferior to 1.5 times that of the current process. Second, the absolute values ​​of the lint coefficient, absorption time, water resistance and usable wash life in the simulation all contain the order of magnitude set by the model. Only the comparison between groups and the directional conclusions are reliable. Third, this model simplifies the washing friction to a one-dimensional axial cumulative slip, and does not take into account the bending fatigue of the fiber, the fiber body fracture, the hydrolytic degradation of polyester by washing chemicals and the clustering effect of the fluff in the wet state; if these mechanisms are significant, they will shorten the absolute life of each group simultaneously, but they do not distinguish the open fiber depth and are not expected to change the directional conclusions between groups.

[0070] The fiber specifications, pile height, alkali concentration, steaming temperature, parameter ranges, and thresholds in the above embodiments are merely examples. Those skilled in the art can adjust them within the scope of this invention according to specific equipment conditions and product requirements. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of this invention should be included within the protection scope of this invention.

Claims

1. A surgical paving lining material comprising a base fabric layer and a pile layer fixed to one side of the base fabric layer, wherein the pile layer is composed of pile formed from island-sea composite filaments, characterized in that, The fibers are divided into open-fiber sections and anchoring sections along their axial direction from tip to root. In the open-fiber sections, the marine component has been removed, and the island components are separated into ultra-fine monofilaments. In the anchoring sections, the marine component is retained, and the island components are still covered by the marine component, forming a composite filament. The anchoring sections extend continuously from the root of the fibers and pass through the surface of the base fabric layer into the embedded section where the fibers are embedded in the base fabric layer, so that the entire length of the embedded section retains the marine component. The ratio R of the axial length h1 of the open-fiber section to the height h0 of the fibers protruding from the surface of the base fabric layer is equal to h1 divided by h0, R is not less than 0.68 and not greater than 0.78, and the axial length of the portion of the anchoring section above the surface of the base fabric layer is not less than 0.15 mm.

2. The velvet-textured lining material for surgical drapes according to claim 1, characterized in that, The height h0 of the pile protruding from the surface of the base fabric layer is 0.6~1.2 mm; the linear density of the monofilament of the island-island composite filament is 0.3~0.6 dtex, the number of island components in each island-island composite filament is 25~40, and the sea component accounts for 25%~35% of the mass fraction of the island-island composite filament; the linear density of the ultrafine monofilament in the fiber-opening section is not greater than 0.02 dtex.

3. The velvet-textured lining material for surgical drapes according to claim 1, characterized in that, The base fabric layer has a microporous polyurethane liquid-resistant layer on the side opposite to the fleece layer, and the fleece material has a water resistance of not less than 30 cm water column.

4. The velvet-textured lining material for surgical drapes according to claim 1, characterized in that, The overall alkali reduction rate of the suede material is 3% to 9%, which is lower than the alkali reduction rate when the pile is opened along its entire length; there is no radial gap formed between the fiber and yarn channels due to the removal of marine components inside the base fabric layer of the suede material.

5. The velvet-textured lining material for surgical drapes according to any one of claims 1 to 4, characterized in that, The fleece material is used as the lining of a reusable surgical drape, and after undergoing no less than 100 washing and sterilization cycles, the commonly used logarithmic value of its lint shedding coefficient, measured by the dry lint shedding test method, is still no greater than 4.

0.

6. A method for preparing a surgical drape lining material, used to prepare the surgical drape lining material according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Using island-sea composite filament as pile yarn to weave the base fabric, the greige fabric is obtained; S2. After scouring and pre-forming the greige fabric, the pile is raised and sheared to form a pile layer on one side of the greige fabric, with the height h0 of the pile protruding from the surface of the base fabric layer being 0.6~1.2 mm. At this time, the island-island composite filaments in the pile have not yet been opened. S3. Alkali is applied to the tip of the pile layer, so that the tip of the pile layer is in contact with the alkali solution layer while the base fabric layer is not in contact with the alkali solution. The thickness d of the alkali solution layer is set to 0.55 to 0.70 times h0 and is adjusted by the gap of the scraper of the liquid supply mechanism. The alkali concentration is 40~80 g / L. S4. Steaming and capillary climbing: the fabric after S3 is steamed at 100~120 degrees Celsius and piled for a time t. During this period, the alkali solution is applied along the axial direction of the pile from the tip to the root capillary. S5. Climbing, the climbing length L1 is equal to the climbing coefficient k multiplied by the square root of time t, wherein the climbing coefficient k is determined by the surface tension and viscosity of the alkaline solution and the equivalent capillary radius of the pile according to the capillary penetration relationship; S6. Timing neutralization cutoff, starting from the time when the alkaline solution comes into contact with the pile tip in S3, when time t reaches the set value, the fabric is put into an acid bath with pH 4~5 to spatially cut off the alkali reduction reaction, wherein the set value makes the axial length h1 of the open fiber segment equal to the sum of the thickness d and the climbing length L1, and the ratio R obtained by dividing h1 by h0 is not less than 0.68 and not greater than 0.78; S7. Washing, drying and post-setting; S8. Coating the side of the base fabric layer away from the pile layer with a microporous polyurethane liquid-resistant layer.

7. The preparation method according to claim 6, characterized in that, The set value of time t in S5 is equal to the difference between the target fiber opening length and the thickness d, divided by the climbing coefficient k, and the square of the quotient. The target fiber opening length is equal to the product of the ratio R and the height h0, and the ratio R is 0.68~0.

78. The ratio of the distance L between the inlet of the acid bath and the outlet of the steam to the linear speed v of the fabric running, plus the conveying time t0 between S3 and S4, equals the set value of time t. The set value of time t is achieved by adjusting the linear speed v.

8. The preparation method according to claim 6, characterized in that, In S3, the contact between the tip of the pile layer and the alkali solution layer is achieved by a liquid feeding roller. The lower part of the liquid feeding roller is immersed in the alkali solution tank. The scraper is attached to the surface of the liquid feeding roller, and the thickness d of the alkali solution layer is determined by the gap between the scraper and the liquid feeding roller. The fabric passes over the liquid feeding roller with the pile layer facing down, and the running tension of the fabric keeps the pile upright and prevents it from being crushed by the liquid feeding roller.

9. The preparation method according to claim 6, characterized in that, In S2, the napping is performed on one side of the fabric using a multi-roller napping machine, and the shearing is performed using a fixed-height shearing mechanism so that the coefficient of variation of the exposed nap height h0 is not greater than 0.15; in S1, the base fabric is made of warp-knitted or woven fabric, and elastic fibers are incorporated into the warp yarns.

10. The preparation method according to claim 6, characterized in that, The preparation method further includes taking samples of the pile material after S6 to measure the longitudinal section of its pile, calculating the actual axial length h1 of the open fiber section based on the distance from the boundary position of the open fiber section and the anchoring section to the surface of the base fabric layer, and correcting the thickness d in S3 and the time t in S5 in reverse according to the deviation between the actual h1 and the target value. When the deviation is positive, the thickness d is reduced, and when the deviation is negative, the time t is increased.

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