Preparation method of polyurethane film with improved rigidity and elasticity after water absorption and special dressing for anorectal department

Abstract

The present invention belongs to the technical field of medical supplies, and specifically relates to a special dressing for anorectal department. The special dressing for anorectal department of the present invention comprises a tape layer, a water-absorbing pad, a dressing core and a release paper. The tape layer has both rigidity and air permeability, can play a good supporting effect, can help anorectal patients to carry out dressing changes within three days after surgery, and effectively prevent wounds from breeding bacteria and inflammatory infections.

Description

Technical Field

[0001] The invention belongs to the technical field of medical supplies, and in particular relates to a special dressing for anorectal department. Background Art

[0002] Currently, anorectal diseases include perianal eczema, abscesses, and hemorrhoids, most of which have the characteristics of large involved areas, inflammatory wounds, and more blood secretions. After the treatment of such diseases, dressings are required for protection and continued treatment and healing.

[0003] However, most of the existing dressings have obvious use defects. For example, the Chinese patent with the authorization announcement number CN 207152708 U discloses a dressing for anorectal surgery. The dressing has been improved in terms of ease of use and fit, but in actual use, the existing anorectal dressings still have obvious use defects.

[0004] The most obvious defect is that after using common dressings, due to their soft and easily deformable characteristics, the dressing effect is poor, the dressing is easy to shift, and it cannot provide good support. The wound is easily rubbed and causes secondary damage. In addition, the existing polyurethane-based dressings have poor air permeability, which makes it easy for the wound to breed bacteria and cause inflammation and infection. Summary of the invention

[0005] In order to solve the problem that after the use of the existing common dressings, the tape of the dressing is too soft to play a good supporting effect, and the polyurethane-based dressing has poor air permeability, which makes the wound easy to breed bacteria and cause inflammation and infection, the present invention provides an anorectal dressing. The present invention includes a tape layer, an absorbent pad, a dressing core and a release paper. The tape layer has both rigidity and air permeability, can play a good supporting effect, can help anorectal patients carry out dressing changes within three days after surgery, and effectively prevent wounds from breeding bacteria and inflammation and infection.

[0006] The specific technical scheme of the present invention is:

[0007] The present invention provides a special dressing for anorectal department, comprising:

[0008] Adhesive tape layer: The adhesive tape layer substrate is composed of non-woven fabric and / or polyurethane film, the front side of the adhesive tape layer substrate is coated with pressure-sensitive adhesive, and the adhesive tape layer substrate at least contains polyurethane film;

[0009] One or more absorbent pads arranged on the front side of the tape layer substrate: made of one or more of viscose fiber, polyester fiber or highly absorbent cotton;

[0010] The core disposed on the surface and / or side of the absorbent pad is a strip-shaped protruding structure made of a foam material for carrying medicine; the absorbent pad and / or the core is covered by a protective layer, and the protective layer extends to the front side of the tape layer substrate.

[0011] After using the existing common dressings, the tape of the dressing is too soft to provide a good supporting effect, and the polyurethane base material dressing has poor air permeability, which makes the wound easy to breed bacteria and cause inflammation and infection. Through the technical solution of the present invention, the water-absorbing pad is arranged on the front of the tape layer base material, and the dressing core is arranged on the surface / side of the water-absorbing pad. During the use of the dressing, the wound is physically protected while the moisture of the wound surface is controlled, and the dressing has excellent air permeability, which reduces the problem that the wound is easy to breed bacteria and cause inflammation and infection.

[0012] In the above structure, the present invention firstly innovatively sets a dressing core, which can play a role of three-dimensional support, meeting the use requirements of common patients with anorectal special dressings, and is made of porous materials at the same time, so that it has the ability to carry drugs. The loaded dressing core can slowly release drugs to the wound during the use of the dressing, and can achieve a certain degree of treatment while achieving physical protection for the wound. Especially in some cases where dressings are difficult to change, the user can apply the drug to the dressing core according to the use requirements, and extend the dressing change cycle by the sustained release of the drug.

[0013] Preferably, the tape layer substrate is a polyurethane film whose rigidity and elasticity are improved after absorbing water.

[0014] The polyurethane film with increased rigidity and elasticity after absorbing water is more in line with the use characteristics of anorectal dressings. Most common anorectal wounds secrete a lot of fluid and are relatively moist. Controlling the moisture of the wound is very important for wound healing, and the wound needs to remain breathable and dry during the healing process. Therefore, the polyurethane film of the present invention with improved rigidity and elasticity after water absorption can more effectively absorb the secretions and moisture of the wound surface, thereby achieving rapid drying of the wound surface. Moreover, most wounds are relatively fragile, and the overall dressing is relatively soft before application, which is beneficial to reducing friction damage to the wound surface. After application, the polyurethane film in the area around the wound surface hardens to a certain extent in the process of absorbing wound secretions and excess moisture, drying the wound surface, and absorbing the secretions and moisture diffused from the dressing core and the absorbent pad into the tape layer. The hardening does not refer to complete hardening, but refers to the formation of a microscopic rigid structure cross-linked network of the material, thereby showing a certain elasticity on a macro scale. The formation of this rigidity is beneficial to protecting the wound surface while forming a second support body that better fits the user's wound morphology, so that the user can obtain a better sense of use and reduce secondary damage caused by friction of the wound surface.

[0015] Preferably, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0016] 1) Mixing polyurethane resin, methyl ethyl ketone and solvent A to obtain a treatment base liquid;

[0017] 2) chitosan, solvent B, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare treatment solution A;

[0018] 3) dissolving the cross-linking agent in solvent C to prepare treatment solution B;

[0019] 4) The non-woven fabric is immersed in the treatment base liquid, immersed once or multiple times and dried to obtain a pre-carrier, the pre-carrier is spread in a container and treatment liquid A is added until the pre-carrier is just immersed, and then treatment liquid B is added to treatment liquid A to cross-link, dry and press to a set thickness, so as to obtain a polyurethane film with improved rigidity and elasticity after water absorption.

[0020] The polyurethane film prepared by the above process first has a certain flexibility, which is based on the chitosan cross-linked gel. The chitosan cross-linked gel can form a soft and hygroscopic aerogel when pressed and dried under certain conditions. When used, it can reduce the friction damage of the wound surface. At the same time, it has very excellent hygroscopicity and is very effective for the rapid drying of the wound surface. The moisture absorbed during the drying process can form an elastic polymer network based on polyurethane resin, polyethylene glycol diacrylate and diisocyanate, so that the overall tape layer has rigidity. The use of non-woven fabric as a carrier is first because the non-woven fabric has good wettability and is easy to prepare. Secondly, it is also because the elastic polymer is easier to form with the non-woven fabric fibers and more effectively forms a mesh structure. When the chitosan gel is coated on the outside, the wound surface can be quickly dried when the user uses it. The moisture absorbed after drying forms an elastic polymer network in the tape layer and achieves a certain shrinkage at the microscopic level. The structural shrinkage pores increase, so that the air permeability of the tape layer will not be weakened due to the absorption of water, ensuring the good air permeability of the tape layer. The rigidity and elasticity formed after application enable the tape layer to better fit the user's wound surface, improving the comfort of use, and supporting the wound surface to avoid damage caused by friction between the wound surface and other adjacent human tissues.

[0021] In addition, it should be noted that absorbent pads usually have a certain water absorption capacity, but they are aimed at secondary secretions of the wound surface, rather than quickly drying and cleaning the wound surface after application. The dressing of the present invention has the characteristics of quickly drying the wound surface and keeping it continuously dry.

[0022] Preferably, in step 1), the mass ratio of the polyurethane resin, methyl ethyl ketone and dimethylformamide is 1:(0.5-0.7):(0.05-0.10).

[0023] Preferably, in step 2), the treatment solution A comprises the following components in parts by weight: 15-17 parts of chitosan, 6-8 parts of glacial acetic acid, 2-3 parts of acrylic polyol, and 1-1.5 parts of diisocyanate.

[0024] Preferably, in step 2), the mass ratio of chitosan to acrylic polyol and diisocyanate is (15-17): (2-3): (1-1.5).

[0025] In the formula of the present invention, by adding chitosan and controlling its addition amount, the softness and moist feeling of the polyurethane film material when drying can be enhanced: the chitosan cross-linked gel can form a soft and hygroscopic aerogel when pressed and dried under certain conditions, which is skin-friendly and soft when used, and has no granular feeling when pressed, thereby reducing the friction damage of the wound surface; at the same time, by adding chitosan and controlling its addition amount, the mass ratio of chitosan to acrylic polyol and diisocyanate in the treatment liquid A is (15-17): (2-3): (1-1.5), the hygroscopicity of the polyurethane film material can be enhanced, and it is very effective for the rapid drying of the wound surface, has excellent air permeability, can keep the surface dry after wetting, and reduces the problem that the wound is easy to breed bacteria and cause inflammation and infection. The moisture absorbed by chitosan during the drying process can form an elastic polymer network based on polyurethane resin, polyethylene glycol diacrylate and diisocyanate. By controlling the ratio between chitosan and acrylic polyol and diisocyanate, the rigidity and elasticity of the polyurethane film material can be enhanced.

[0026] Preferably, in step 3), the solvent C of the treatment liquid B is water.

[0027] Preferably, the cross-linking agent used in the treatment solution B in step 3) is anhydrous calcium chloride;

[0028] The concentration of CaCl2 in the treatment solution B is 1-3 wt%.

[0029] The above cross-linking agents are common and frequently used cross-linking agents with good use effects.

[0030] Preferably, the foam material of the core coating is porous polyurethane soft foam.

[0031] Porous polyurethane soft foam is a common and human-friendly material with strong drug-carrying capacity and certain sustained-release ability.

[0032] Preferably, the cross section of the core is semicircular, circular or trapezoidal;

[0033] The absorbent pad is adhered to the side of the core and extends to the front side of the tape layer substrate.

[0034] The semicircular dressing core is the best choice for the anorectal dressing of the present invention, and the absorbent pad formed by the semicircular dressing core is as follows: Figure 1 and Figure 2 The shape shown is similar to Ω, which has good fit for anorectal patients and common anorectal wounds.

[0035] Preferably, the protective layer is a polyethylene (PE) mesh isolation film.

[0036] The above-mentioned diaphragm has good air permeability and moisture permeability, and it mainly plays the role of fixing and physically protecting the internal core and absorbent pad.

[0037] Preferably, at least one side edge of the outer contour of the tape layer is provided with a notch.

[0038] The notch is arranged on the side of the outer contour corresponding to the length direction of the core dressing strip, which is conducive to the folding of the tape layer and makes it convenient for the user to distinguish the orientation of the core dressing, thereby improving the ease of use of the overall dressing.

[0039] Preferably, notches are provided at both side edges of the outer contour of the tape layer, and the notches are arranged on both sides symmetrically of the outer contour of the substrate.

[0040] Notches on both sides are more conducive to dressing alignment and identification of the dressing core position, further enhancing the ease of use of the entire dressing.

[0041] Preferably, the anorectal dressing further comprises release paper adhered to both edges and covering the front of the tape layer, and the release paper is adhered to both edges of the tape layer without a gap. Figure 1 and Figure 2 As shown, two pieces of release paper are provided, which are respectively adhered to the two side edges of the tape layer without notches, and partially overlapped to ensure the cleanliness of the front side of the tape layer and the core coating structure.

[0042] Compared with the prior art, the beneficial effects of the present invention are:

[0043] (1) The anorectal dressing of the present invention forms a dual support inside and outside through the dressing core and the tape layer with the characteristics of increased rigidity and elasticity after absorbing water. The dual support effect can ensure a very excellent protection effect on the wound, effectively form a structural support at the wound, and reduce friction at the wound;

[0044] (2) The anorectal dressing of the present invention has the ability to quickly dry the wound surface and keep the wound surface clean for a long time, and the dressing as a whole has good air permeability;

[0045] (3) The dressing also has the ability to carry and deliver drugs, which significantly promotes wound recovery. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 This is a schematic diagram of the axial structure of the special dressing for anorectal department of the present invention;

[0047] Figure 2 It is a front view structural schematic diagram and a partial enlarged diagram of the special dressing for anorectal department of the present invention;

[0048] Figure 3 This is the SEM characterization result of the substrate of Example 1 of the present invention;

[0049] Figure 4 It is a schematic diagram of the rigidity performance test of the present invention;

[0050] In the figure: 10 experimental dressing, 20 V template, 100 tape layer, 100a substrate front, 101 notch, 200 dressing core, 300 absorbent pad, 400 protective layer, 500 release paper. DETAILED DESCRIPTION

[0051] The present invention will be further described below in conjunction with the embodiments.

[0052] Overall embodiment

[0053] A special dressing for anorectal department, comprising:

[0054] Adhesive tape layer: The adhesive tape layer substrate is composed of non-woven fabric and / or polyurethane film, the front side of the adhesive tape layer substrate is coated with pressure-sensitive adhesive, and the adhesive tape layer substrate at least contains polyurethane film;

[0055] One or more absorbent pads arranged on the front side of the tape layer substrate: made of one or more of viscose fiber, polyester fiber or highly absorbent cotton;

[0056] The core disposed on the surface and / or side of the absorbent pad is a strip-shaped protruding structure made of a foam material for carrying medicine; the absorbent pad and / or the core is covered by a protective layer, and the protective layer extends to the front side of the tape layer substrate.

[0057] Preferably, the tape layer substrate is a polyurethane film whose rigidity and elasticity are improved after absorbing water.

[0058] Preferably, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0059] 1) Mixing polyurethane resin, methyl ethyl ketone and solvent A to obtain a treatment base liquid;

[0060] 2) chitosan, solvent B, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare treatment solution A;

[0061] 3) dissolving the cross-linking agent in solvent C to prepare treatment solution B;

[0062] 4) The non-woven fabric is immersed in the treatment base liquid, immersed once or multiple times and dried to obtain a pre-carrier, the pre-carrier is spread in a container and treatment liquid A is added until the pre-carrier is just immersed, and then treatment liquid B is added to treatment liquid A to cross-link, dry and press to a set thickness, so as to obtain a polyurethane film with improved rigidity and elasticity after water absorption.

[0063] Preferably, in step 1), the mass ratio of the polyurethane resin, methyl ethyl ketone and dimethylformamide is 1: (0.5-0.7): (0.05-0.10);

[0064] Preferably, in step 2), the treatment solution A comprises the following components in parts by weight: 15 to 17 parts of chitosan, 6 to 8 parts of glacial acetic acid, 2 to 3 parts of acrylic polyol, and 1 to 1.5 parts of diisocyanate;

[0065] Preferably, in step 2), the mass ratio of chitosan to acrylic polyol and diisocyanate is (15-17): (2-3): (1-1.5).

[0066] Preferably, in step 3), the solvent C of the treatment liquid B is water;

[0067] Preferably, the cross-linking agent used in the treatment solution B in step 3) is anhydrous calcium chloride;

[0068] The concentration of CaCl2 in the treatment solution B is 1-3 wt%.

[0069] Preferably, the foam material of the core coating is porous polyurethane soft foam.

[0070] Preferably, the cross section of the core is semicircular, circular or trapezoidal;

[0071] The absorbent pad is adhered to the side of the core and extends to the front side of the tape layer substrate.

[0072] Preferably, the protective layer is a polyethylene (PE) mesh isolation film.

[0073] Preferably, at least one side edge of the outer contour of the tape layer is provided with a notch.

[0074] Preferably, notches are provided at both side edges of the outer contour of the tape layer, and the notches are arranged on both sides symmetrically of the outer contour of the substrate.

[0075] Preferably, the anorectal dressing further comprises release paper adhered to both edges and covering the front side of the tape layer, and the release paper is adhered to both edges of the tape layer without a notch.

[0076] Example 1

[0077] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0078] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0079] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0080] On both sides of the dressing core, there are water-absorbing pads of equal length, which fit the edges of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0081] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0082] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0083] Specifically,

[0084] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0085] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.6:0.08, and defoamed to obtain a treatment base liquid;

[0086] 2) chitosan, glacial acetic acid, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare a treatment liquid A, wherein the chitosan content of the treatment liquid A is 16wt%, the glacial acetic acid content is 7wt%, the acrylic polyol content is 2.5wt%, the diisocyanate content is 1.2wt%; and the rest is water;

[0087] 3) dissolving anhydrous calcium chloride in water to prepare a 2 wt % treatment solution B;

[0088] 4) The non-woven fabric is soaked in the treatment base liquid, soaked twice and dried to obtain a pre-carrier, the pre-carrier is spread in a container and the treatment liquid A is added until the pre-carrier is just immersed, and then the treatment liquid B is added to the treatment liquid A, and the volume ratio of the treatment liquid A to the treatment liquid B is 1:1. Treat at 30°C for 1h, then dry on a 60°C hot plate and press to a set thickness (1mm), cut into a size of 14cm×16cm to obtain the desired finished polyurethane film with improved rigidity and elasticity after water absorption.

[0089] The tape layer substrate was characterized by SEM, and the characterization results are as follows: Figure 3 As shown. From the characterization results, it can be seen that it has obvious cross-linked network morphology characteristics. And it maintains a large number of pores to have good moisture absorption and air permeability. From the above experimental results, it can be seen that the anorectal dressing of the present invention has the ability to quickly absorb moisture and water.

[0090] Example 1 also provides a method for testing the rapid drying ability:

[0091] Take the prepared anorectal dressing and lay it flat on the test bench with the front of the substrate facing up. After tearing off the release paper, quickly drip 10 mL of deionized water on the front of the anorectal dressing substrate. After standing for 15 seconds, gently lay a piece of absorbent paper. If the absorbent paper can be blown away from the anorectal dressing, the test is OK, otherwise it is NG. Each experimental group was conducted 20 times, and a new dressing was used each time.

[0092] Table 1 Rapid drying ability test results

[0093] It can be seen from the rapid drying ability test results that the anorectal dressing of the present invention has very excellent rapid moisture absorption ability.

[0094] Example 1 also provides a rigidity characterization-elastic recovery force characterization test method:

[0095] like Figure 4 As shown, a V-shaped plate with an opening angle of 30° was used as the experimental plate, and the prepared anorectal dressing was used as the experimental dressing. After the inner surface of the V-shaped plate was moistened with deionized water, the release paper of the experimental dressing was torn off and applied to the inner angle of the V-shaped plate. It was allowed to stand for 15 seconds, and then the V-shaped plate was pressed until its opening angle was reduced to 15°. After repeating 50 times, the morphological characteristics of the experimental dressing were observed.

[0096] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test and a rigidity characterization-elastic recovery force characterization test. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1. The anorectal dressing prepared in this embodiment remained attached to the surface of the V-shaped plate in the rigidity characterization-elastic recovery force characterization test without wrinkling, and the force required during the pressing process was relatively large.

[0097] It can be seen from the rigidity characterization-elastic recovery force characterization test results that the special dressing for anorectal department of the present invention has a certain rigidity and can ensure good protection of the wound surface.

[0098] Example 1 also provides a sensory evaluation method:

[0099] 20 volunteers conducted a sensory evaluation on the anorectal dressing. They touched the inner layer of the anorectal dressing that contacts the skin with their hands and scored it according to the softness. 8-10 points indicated very softness, 4-7 points indicated acceptable softness, and 0-3 points indicated insufficient softness. The average value was taken after the scores of the volunteers. The sensory evaluation results of the anorectal dressings of Examples 1-5 and Comparative Examples 1-2 are shown in Table 2.

[0100] Table 2 Sensory evaluation results

[0101] Softness Example 1 8.8 Example 2 9.5 Example 3 8.2 Example 4 7.5 Example 5 7.9 Comparative Example 1 7.0 Comparative Example 2 6.0

[0102] It can be seen from the sensory evaluation results that the anorectal dressing prepared in this embodiment is very soft and slightly moist to the touch and is skin-friendly.

[0103] Example 2

[0104] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0105] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0106] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0107] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0108] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0109] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0110] Specifically,

[0111] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0112] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.5:0.05, and defoamed to obtain a treatment base liquid;

[0113] 2) chitosan, glacial acetic acid, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare a treatment liquid A, wherein the chitosan content of the treatment liquid A is 15wt%, the glacial acetic acid content is 6wt%, the acrylic polyol content is 2wt%, the diisocyanate content is 1wt%; and the rest is water;

[0114] 3) dissolving anhydrous calcium chloride in water to prepare a 1 wt % treatment solution B;

[0115] 4) The non-woven fabric is soaked in the treatment base liquid for 3 times and dried to obtain a pre-carrier. The pre-carrier is spread in a container and the treatment liquid A is added until the pre-carrier is just immersed. Then, the treatment liquid B is added to the treatment liquid A. The volume ratio of the treatment liquid A to the treatment liquid B is 1:1. The pre-carrier is treated at 25°C for 1.5 hours, and then dried on a hot plate at 60°C and pressed to a set thickness (1mm). After cutting into a size of 14cm×16cm, the desired finished polyurethane film with improved rigidity and elasticity after water absorption is obtained.

[0116] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. The anorectal dressing prepared in this embodiment remained attached to the surface of the V-shaped plate in the rigidity characterization-elastic recovery force characterization test without wrinkling, and the force required during the pressing process was relatively large.

[0117] It can be seen from the results of the rapid drying ability test that the anorectal dressing of the present invention has a very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing of the present invention has a certain rigidity, which can ensure good protection of the wound surface. It can be seen from the sensory evaluation results that the anorectal dressing prepared in this embodiment is very soft to the touch and has a slight moist feeling, and is skin-friendly.

[0118] Example 3

[0119] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0120] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0121] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0122] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0123] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0124] In addition, there are release papers, such as Figure 1 and Figure 2As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0125] Specifically,

[0126] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0127] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.7:0.10, and defoamed to obtain a treatment base liquid;

[0128] 2) chitosan, glacial acetic acid, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare a treatment solution A, wherein the chitosan content of the treatment solution A is 17wt%, the glacial acetic acid content is 8wt%, the acrylic polyol content is 3wt%, the diisocyanate content is 1.5wt%; and the rest is water;

[0129] 3) dissolving anhydrous calcium chloride in water to prepare a 3 wt % treatment solution B;

[0130] 4) The non-woven fabric is soaked in the treatment base liquid, soaked once and dried to obtain a pre-carrier, the pre-carrier is spread flat in a container, and treatment liquid A is added until the pre-carrier is just immersed, and then treatment liquid B is added to treatment liquid A, and the volume ratio of treatment liquid A to treatment liquid B is 1:1. Treat at 30°C for 1h, then dry on a 60°C hot plate and press to a set thickness (1mm), cut into a size of 14cm×16cm to obtain the desired finished polyurethane film with improved rigidity and elasticity after water absorption.

[0131] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. The anorectal dressing prepared in this embodiment remained attached to the surface of the V-shaped plate in the rigidity characterization-elastic recovery force characterization test without wrinkling, and the force required during the pressing process was relatively large.

[0132] It can be seen from the results of the rapid drying ability test that the anorectal dressing of the present invention has a very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing of the present invention has a certain rigidity, which can ensure good protection of the wound surface. It can be seen from the sensory evaluation results that the anorectal dressing prepared in this embodiment is very soft to the touch and has a slight moist feeling, and is skin-friendly.

[0133] Example 4

[0134] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0135] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0136] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0137] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0138] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0139] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0140] Specifically,

[0141] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0142] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.6:0.08, and defoamed to obtain a treatment base liquid;

[0143] 2) Chitosan and glacial acetic acid are co-dissolved to prepare a treatment solution A, wherein the treatment solution A contains 16 wt % chitosan, 7 wt % glacial acetic acid, 4 wt % acrylic polyol, 2 wt % diisocyanate, and the rest is water;

[0144] 3) dissolving anhydrous calcium chloride in water to prepare a 2 wt % treatment solution B;

[0145] 4) The non-woven fabric is soaked in the treatment base liquid, soaked twice and dried to obtain a pre-carrier, the pre-carrier is spread in a container and the treatment liquid A is added until the pre-carrier is just immersed, and then the treatment liquid B is added to the treatment liquid A, and the volume ratio of the treatment liquid A to the treatment liquid B is 1:1. Treat at 30°C for 1h, then dry on a 60°C hot plate and press to a set thickness (1mm), cut into a size of 14cm×16cm to obtain the desired finished polyurethane film.

[0146] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. In the rigidity characterization-elastic recovery force characterization test, the anorectal dressing prepared in Example 4 showed slight wrinkles on the tape layer after the pressing was completed, but the wrinkles were not obvious, and the force required during the pressing process was relatively large.

[0147] It can be seen from the results of the rapid drying ability test that the anorectal dressing prepared in Example 4 has very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing prepared in Example 4 has average rigidity and good elasticity. It can be seen from the sensory evaluation results that the anorectal dressing prepared in Example 4 is soft to the touch, has no granular feeling when pressed, and has a slight moist feeling.

[0148] Compared with Example 1, the anorectal dressing prepared in Example 4 has poor rigidity and elasticity, and the softness of the sensory evaluation is discounted. Based on theoretical and experimental research, the present invention team found that when chitosan is added and its addition amount is controlled, the mass ratio of chitosan to acrylic polyol and diisocyanate in the treatment liquid A is (15-17): (2-3): (1-1.5), the hygroscopicity of the polyurethane film material can be enhanced, and it is very effective for the rapid drying of the wound surface, has excellent air permeability, and can keep the surface dry after wetting, reducing the problem of wounds easily breeding bacteria and causing inflammation and infection. The moisture absorbed by chitosan during the drying process can form an elastic polymer network based on polyurethane resin, polyethylene glycol diacrylate and diisocyanate. By controlling the ratio between chitosan and acrylic polyol and diisocyanate, the rigidity and elasticity of the polyurethane film material can be enhanced.

[0149] Example 5

[0150] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0151] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0152] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0153] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0154] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0155] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0156] Specifically,

[0157] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0158] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.6:0.08, and defoamed to obtain a treatment base liquid;

[0159] 2) Chitosan and glacial acetic acid are co-dissolved to prepare a treatment solution A, wherein the treatment solution A contains 16 wt % chitosan, 7 wt % glacial acetic acid, 1 wt % acrylic polyol, 0.5 wt % diisocyanate, and the rest is water;

[0160] 3) dissolving anhydrous calcium chloride in water to prepare a 2 wt % treatment solution B;

[0161] 4) The non-woven fabric is soaked in the treatment base liquid, soaked twice and dried to obtain a pre-carrier, the pre-carrier is spread in a container and the treatment liquid A is added until the pre-carrier is just immersed, and then the treatment liquid B is added to the treatment liquid A, and the volume ratio of the treatment liquid A to the treatment liquid B is 1:1. Treat at 30°C for 1h, then dry on a 60°C hot plate and press to a set thickness (1mm), cut into a size of 14cm×16cm to obtain the desired finished polyurethane film.

[0162] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. In the rigidity characterization-elastic recovery force characterization test, the anorectal dressing prepared in Example 5 showed slight wrinkles in the tape layer after the pressing was completed, but the wrinkles were not obvious, and the force required during the pressing process was relatively large.

[0163] It can be seen from the results of the rapid drying ability test that the anorectal dressing prepared in Example 5 has very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing prepared in Example 5 has average rigidity and good elasticity. It can be seen from the sensory evaluation results that the anorectal dressing prepared in Example 5 is soft to the touch and has a slight moist feeling.

[0164] Compared with Example 1, the anorectal dressing prepared in Example 5 has poor rigidity and elasticity. Based on theoretical and experimental research, the present invention team found that when chitosan is added and its addition amount is controlled so that the mass ratio of chitosan to acrylic polyol and diisocyanate in the treatment liquid A is (15-17): (2-3): (1-1.5), the hygroscopicity of the polyurethane film material can be enhanced, and it is very effective for the rapid drying of the wound surface, has excellent air permeability, and can keep the surface dry after wetting, reducing the problem of wounds easily breeding bacteria and causing inflammation and infection. The moisture absorbed by chitosan during the drying process can form an elastic polymer network based on polyurethane resin, polyethylene glycol diacrylate and diisocyanate. By controlling the ratio between chitosan and acrylic polyol and diisocyanate, the rigidity and elasticity of the polyurethane film material can be enhanced.

[0165] Comparative Example 1

[0166] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0167] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0168] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0169] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0170] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0171] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0172] Specifically,

[0173] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0174] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.6:0.08, and defoamed to obtain a treatment base liquid;

[0175] 2) Chitosan and glacial acetic acid are co-dissolved to prepare a treatment solution A, wherein the chitosan content of the treatment solution A is 16 wt %, the glacial acetic acid content is 7 wt % and the rest is water;

[0176] 3) dissolving anhydrous calcium chloride in water to prepare a 2 wt % treatment solution B;

[0177] 4) The non-woven fabric is soaked in the treatment base liquid, soaked twice and dried to obtain a pre-carrier, the pre-carrier is spread in a container and the treatment liquid A is added until the pre-carrier is just immersed, and then the treatment liquid B is added to the treatment liquid A, and the volume ratio of the treatment liquid A to the treatment liquid B is 1:1. Treat at 30°C for 1h, then dry on a 60°C hot plate and press to a set thickness (1mm), cut into a size of 14cm×16cm to obtain the desired finished polyurethane film.

[0178] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. In the rigidity characterization-elastic recovery force characterization test, the anorectal dressing prepared in Comparative Example 1 showed obvious wrinkles after the pressing, and obvious creases appeared in the middle, and the force required for the pressing process was relatively small.

[0179] It can be seen from the results of the rapid drying ability test that the anorectal dressing prepared in Comparative Example 1 has very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing prepared in Comparative Example 1 has poor rigidity and poor elastic recovery force. It can be seen from the sensory evaluation results that the anorectal dressing prepared in Comparative Example 1 has a noticeable softness and a slight moist feeling to the touch, and is skin-friendly.

[0180] Compared with Example 1, the anorectal dressing prepared in Example 1 has poor rigidity and poor elastic recovery. Based on theoretical and experimental research, the present invention team found that the anorectal dressing prepared by adding acrylic polyol and diisocyanate to the treatment liquid A has very excellent rapid moisture absorption capacity and has a certain rigidity, which can ensure good protection of the wound surface.

[0181] Comparative Example 2

[0182] A kind of Figure 1 and Figure 2 The anorectal dressing shown includes:

[0183] A 14 cm wide and 16 cm long polyurethane film substrate whose rigidity and elasticity are improved after water absorption, a pressure-sensitive adhesive is coated on the front side of the substrate to form a tape layer, and a notch is provided in the middle of both ends of the substrate in the length direction;

[0184] And a semicircular porous polyurethane soft foam with a radius of 1 cm and a length of 8 cm is used as a core for drug loading and sustained drug release. For example, the core purchased in this embodiment is a unidirectional porous polyurethane soft foam, which has the characteristics of loading and delivering drugs perpendicular to the tape layer. After it is attached to the wound, it can more effectively achieve directional and precise drug delivery. When it is set, the length direction is parallel to the length direction of the substrate and adhered to the middle of the front side of the substrate;

[0185] On both sides of the dressing core, there are water-absorbing pads of equal length, which are attached to both sides of the edge of the dressing core and extend to the surface of the tape layer, forming an overall structure similar to an Ω shape, so as to fix the dressing core and absorb the secondary secretion of the wound surface when the dressing core releases the drug, so as to clean the wound surface;

[0186] The surface of the core and the absorbent pad is covered with a polyethylene PE mesh isolation film, which extends to the front side of the substrate of the tape layer and is adhered and fixed to the front side of the substrate. The setting of the polyethylene PE mesh isolation film ensures that the absorbent pad and the core can realize their original functions while improving the setting stability of the two.

[0187] In addition, there are release papers, such as Figure 1 and Figure 2 As shown, the release paper is provided with two pieces, which are respectively adhered to the two side edges of the tape layer without a notch, and at the same time Figure 2 As shown, after the normal flat release paper is set, some overlap is formed to ensure the cleanliness of the front side of the tape layer and the core coating and other structures.

[0188] Specifically,

[0189] In this embodiment, the polyurethane film with improved rigidity and elasticity after water absorption is prepared by the following process:

[0190] 1) polyurethane resin, methyl ethyl ketone and dimethylformamide are mixed in a mass ratio of 1:0.6:0.08, and defoamed to obtain a treatment base liquid;

[0191] 2) Polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare a treatment liquid, wherein the content of acrylic polyol in the treatment liquid is 2.5 wt %, the content of diisocyanate is 1.2 wt % and the rest is water;

[0192] 3) The non-woven fabric is soaked in the treatment base liquid, soaked twice and dried to obtain a pre-carrier, the pre-carrier is spread flat in a container and the treatment liquid is added until the pre-carrier is just immersed, and the pre-carrier is treated at 30°C for 1 hour, and then dried on a 60°C hot plate and pressed to a set thickness (1mm), and cut into a size of 14cm×16cm to obtain the desired finished polyurethane film with improved rigidity and elasticity after water absorption.

[0193] The anorectal dressing prepared in this embodiment was subjected to a quick drying ability test, a rigidity characterization-elastic recovery force characterization test and a sensory evaluation. The results of the quick drying ability test of the anorectal dressing prepared in this embodiment are shown in Table 1, and the sensory evaluation results are shown in Table 2. In the rigidity characterization-elastic recovery force characterization test, the anorectal dressing prepared in Comparative Example 2 showed slight wrinkles in the tape layer after the pressing was completed, but the wrinkles were not obvious, and the force required during the pressing process was relatively large.

[0194] It can be seen from the results of the rapid drying ability test that the anorectal dressing prepared in Comparative Example 2 has very excellent rapid moisture absorption ability. It can be seen from the results of the rigidity characterization-elastic recovery force characterization test that the anorectal dressing prepared in Comparative Example 2 has average rigidity and average elastic recovery force. It can be seen from the sensory evaluation results that the anorectal dressing prepared in Comparative Example 2 has a noticeable softness to the touch, a slight granularity when pressed, and no moist feeling.

[0195] Compared with Example 1 and Comparative Example 1, the anorectal dressing prepared in Comparative Example 2 is not skin-friendly, has average rigidity, and average elastic recovery. Based on theoretical and experimental research, the present invention team found that chitosan, glacial acetic acid, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare treatment liquid A, and the cross-linking agent is dissolved in solvent C to prepare treatment liquid B. The anorectal dressing that can be prepared has very excellent rapid moisture absorption capacity and a certain rigidity, which can ensure good protection of the wound surface.

[0196] The raw materials and equipment used in the present invention, unless otherwise specified, are all commonly used raw materials and equipment in the art; the methods used in the present invention, unless otherwise specified, are all conventional methods in the art.

[0197] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any way. Any simple modification, change and equivalent transformation made to the above embodiment based on the technical essence of the present invention still falls within the protection scope of the technical solution of the present invention.

Claims

1. A method for preparing a polyurethane film with improved rigidity and elasticity after water absorption, characterized in that: 1) Mix polyurethane resin, methyl ethyl ketone and dimethylformamide to obtain a treatment base liquid; 2) Chitosan, glacial acetic acid, polyethylene glycol diacrylate and diisocyanate are co-dissolved to prepare treatment solution A; 3) dissolving the cross-linking agent in water to prepare treatment solution B; 4) soaking the non-woven fabric in the treatment base liquid, soaking it once or multiple times and drying it to obtain a pre-carrier, spreading the pre-carrier in a container, adding the treatment liquid A until the pre-carrier is just immersed, then adding the treatment liquid B to the treatment liquid A, cross-linking reaction, drying and pressing to a set thickness, that is, obtaining a polyurethane film with improved rigidity and elasticity after water absorption; In step 2), the mass ratio of chitosan to polyethylene glycol diacrylate and diisocyanate is (15-17): (2-3): (1-1.5).

2. The method for preparing a polyurethane film with improved rigidity and elasticity after water absorption according to claim 1, characterized in that: In step 1), the mass ratio of the polyurethane resin, methyl ethyl ketone and dimethylformamide is 1: (0.5-0.7): (0.05-0.10).

3. The method for preparing a polyurethane film with improved rigidity and elasticity after water absorption according to claim 1, characterized in that: Step 3) The cross-linking agent used in the treatment solution B is anhydrous calcium chloride; The concentration of CaCl2 in the treatment solution B is 1-3 wt%.

4. A special dressing for anorectal department, characterized in that: include: The adhesive tape layer comprises an adhesive tape layer substrate made of a polyurethane film with improved rigidity and elasticity after water absorption obtained by the preparation method of claim 1, and a pressure-sensitive adhesive is coated on the front side of the adhesive tape layer substrate; One or more absorbent pads arranged on the front side of the tape layer substrate: made of one or more of viscose fiber, polyester fiber or highly absorbent cotton; The core disposed on the surface and / or side of the absorbent pad is a strip-shaped protruding structure made of a foam material for carrying medicine; the absorbent pad and / or the core is covered by a protective layer, and the protective layer extends to the front side of the tape layer substrate.

5. The anorectal dressing according to claim 4, characterized in that: The foam material of the core coating is porous polyurethane soft foam.

6. The anorectal dressing according to claim 4, characterized in that: The cross section of the core is semicircular, circular or trapezoidal; The absorbent pad is adhered to the side of the core and extends to the front side of the tape layer substrate.

7. The anorectal dressing according to claim 4, characterized in that: The protective layer is a polyethylene mesh isolation film.

8. The anorectal dressing according to claim 4, characterized in that: At least one side edge of the outer contour of the tape layer is provided with a notch.

9. The anorectal dressing according to claim 8, characterized in that: Notches are arranged on both sides of the outer contour of the adhesive tape layer, and the notches are arranged on both sides of the outer contour of the substrate which are symmetrical.

10. The anorectal dressing according to claim 9, characterized in that: The anorectal dressing also includes release paper adhered to both edges and covering the front side of the tape layer, and the release paper is adhered to both edges of the tape layer without gaps.

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