A medical hydrocolloid dressing and a method of making the same

Abstract

The application discloses a medical hydrogel dressing and a preparation method thereof, and relates to the technical field of medical dressings. A base premix is prepared from a thermoplastic elastomer, tackifying resin and hydrophilic polymer particles, then dry alginate salt powder is added and a soluble calcium salt solution is atomized and added to form a pre-crosslinking mixture through in-situ ion crosslinking; subsequently, a foaming agent, a gas generating acid and a layered silicate / water-soluble polymer pre-interlayer composite powder are introduced to construct a microporous structure through in-situ foaming in the base through a gas generating reaction, and after heat pressing and setting, drying is performed, and finally a breathable film backing is hot-pressed and compounded. The method cooperatively constructs ion crosslinking and a microporous structure, so that the dressing has high gel cohesion and high air permeability, and the structure is complete and does not fall off after liquid absorption.

Description

Technical Field

[0001] This invention relates to the field of medical dressing technology, specifically to a medical hydrocolloid dressing and its preparation method. Background Technology

[0002] Hydrocolloid dressings are a widely used type of moist wound care material in clinical practice. Their core structure consists of hydrophilic polymer particles dispersed in a heat-melt pressure-sensitive adhesive matrix. During use, the hydrocolloid particles absorb wound exudate and swell, forming a moist gel layer that maintains a suitable healing microenvironment. However, existing hydrocolloid dressings still face two significant technical bottlenecks in practical clinical applications: First, insufficient gel cohesion. After absorbing a large amount of exudate, the hydrophilic polymers in hydrocolloid dressings (such as sodium carboxymethyl cellulose and gelatin) undergo excessive swelling of the gel system, significantly weakening the physical entanglement and hydrogen bonding between molecular chains. This results in a loose gel structure and decreased cohesion, manifesting as gel residue, displacement, and even disintegration during use, severely impacting wound care effectiveness and patient experience. Second, limited breathability. Traditional hydrocolloid dressings typically use a polyurethane film as a backing layer. While this provides good waterproof and antibacterial properties, the gel layer itself is relatively dense, resulting in low water vapor permeability. In clinical applications, normal wound metabolism requires a certain amount of gas exchange. Insufficient breathability can easily lead to increased local wound temperature, exudate accumulation, increased risk of maceration, and even secondary infection, which is detrimental to normal wound healing. Therefore, how to improve the gel cohesion and breathability of hydrocolloid dressings while ensuring their basic absorbency is a technical problem that urgently needs to be solved in this field. Summary of the Invention

[0003] The purpose of this invention is to provide a medical hydrocolloid dressing and its preparation method to solve the technical problems mentioned in the background.

[0004] To achieve the above objectives, the present invention provides the following technical solution: A method for preparing a medical hydrocolloid dressing includes the following steps: (1) The thermoplastic elastomer and the tackifying resin are mixed and melted, and then hydrophilic polymer particles are added and mixed evenly to obtain a hydrocolloid matrix premix. (2) Add alginate powder to the hydrocolloid matrix premix for dispersion, and then atomize and add soluble calcium salt solution to make alginate and calcium ions undergo in-situ ionic cross-linking to obtain a pre-cross-linked hydrocolloid mixture; (3) Add a foaming agent, a gas-producing acid and a layered silicate / water-soluble polymer pre-intercalation composite powder to the pre-crosslinked hydrocolloid mixture and mix them so that the foaming agent and the gas-producing acid react to produce gas and foam in situ inside the matrix to form a microporous structure. Then, perform hot pressing to shape and obtain a hydrocolloid sheet with a microporous structure. (4) The hydrocolloid sheet is dried and then hot-pressed with a breathable film backing to obtain the final product.

[0005] Preferably, the thermoplastic elastomer in step (1) is a styrene-isoprene-styrene block copolymer; The tackifying resin is pentaerythritol rosin; The hydrophilic polymer particles are a mixture of sodium carboxymethyl cellulose and gelatin.

[0006] Preferably, in step (1), a hindered phenolic antioxidant is added when mixing and melting the thermoplastic elastomer and the tackifying resin.

[0007] As a preferred option, the specific operation steps of step (1) are as follows: First, 20-30 parts by weight of the thermoplastic elastomer, 5-10 parts by weight of the tackifying resin and 0.3-1 parts by weight of the hindered phenolic antioxidant are mixed at 120-140°C for 15-25 minutes to form a hot melt pressure-sensitive adhesive matrix. Then, the temperature is lowered to 90-100°C, and the hydrophilic polymer particles are added and the mixture is continued to be mixed for 8-15 minutes. The hydrophilic polymer particles include 25-35 parts by weight of sodium carboxymethyl cellulose and 5-10 parts by weight of gelatin.

[0008] Preferably, the alginate is sodium alginate; The soluble calcium salt is calcium chloride; Preferably, the sodium alginate is added to the hydrocolloid matrix premix in dry powder form at 80-100°C and mixed for 8-12 minutes; the calcium chloride is dissolved in deionized water to prepare a calcium chloride solution with a mass concentration of 10%-15%, and the calcium chloride solution is added by atomization spraying while the mixture is in a mixed state, and mixing is continued at 80-100°C for 15-25 minutes.

[0009] Preferably, the mass ratio of sodium alginate to calcium chloride is 5:(1-3).

[0010] Preferably, the foaming agent in step (3) is sodium bicarbonate; The gas-producing acid is L-tartaric acid; The specific steps of step S3 are as follows: First, add the sodium bicarbonate to the pre-crosslinked hydrocolloid mixture at 50-60°C and mix for 3-5 minutes. Then, add the L-tartaric acid and the layered silicate / water-soluble polymer pre-intercalation composite powder and continue mixing at 55-70°C for 5-8 minutes to initiate a foaming reaction. After the gas generation is basically completed, quickly transfer the material to a flat vulcanizing machine at 90-105°C for pressing and shaping for 5-10 minutes.

[0011] Preferably, the preparation method of the layered silicate / water-soluble polymer pre-intercalated composite powder is as follows: Polyvinyl alcohol is added to water and stirred to dissolve, thus preparing a polyvinyl alcohol aqueous solution; Montmorillonite was added to the polyvinyl alcohol aqueous solution, stirred at 60-70°C and subjected to ultrasonic dispersion treatment to allow the montmorillonite sheets to be intercalated and dispersed in the polyvinyl alcohol solution, thus obtaining a montmorillonite / polyvinyl alcohol composite dispersion. The composite dispersion was spray-dried to obtain the montmorillonite / polyvinyl alcohol pre-intercalated composite powder.

[0012] Preferably, step (4) further includes sealing and packaging the hot-pressed composite product in a nitrogen atmosphere and subjecting it to irradiation sterilization.

[0013] A medical hydrocolloid dressing is prepared by the method described above.

[0014] Compared with the prior art, the beneficial effects of the present invention are: 1. This invention abandons the traditional method of maintaining gel through physical entanglement and hydrogen bonding using sodium carboxymethyl cellulose and gelatin, instead introducing sodium alginate and using calcium chloride for ionic cross-linking. Utilizing the egg-box coordination structure formed by calcium ions and sodium alginate G blocks, a layer of chemically cross-linked ionic gel network is superimposed on the original physical gel network. After liquid absorption and swelling, the two networks interpenetrate and work together to bear load. Even if the physically cross-linked portion is weakened by water molecules, the chemically cross-linked egg-box framework can still stably serve as a load-bearing frame. This fundamentally improves the overall cohesion and anti-swelling deformation ability of the gel system, allowing the dressing to maintain its structural integrity even after absorbing a large amount of exudate, completely solving the problem of gel loosening, disintegration, and detachment after liquid absorption in traditional hydrocolloids.

[0015] 2. Sodium bicarbonate and tartaric acid react in situ within the colloidal matrix to generate carbon dioxide gas, forming numerous uniform and interconnected microporous channels within the incompletely cured matrix. These channels are then fixed after hot pressing. These micropores penetrating the colloidal layer provide effective diffusion pathways for water vapor and gas, significantly improving the dressing's water vapor permeability and preventing excessive local humidity on the wound surface. Crucially, the foaming byproduct sodium tartrate is safe and non-toxic, and has extremely weak chelating ability for calcium ions, significantly reducing the risk of disrupting the calcium alginate ion cross-linking network. Simultaneously, the microporous structure increases the contact area with exudate, achieving high air permeability without sacrificing the dressing's absorbency, thus simultaneously optimizing air permeability and absorbency.

[0016] 3. The stepwise feeding method is adopted. Sodium bicarbonate is first uniformly dispersed in the matrix at a lower temperature, and then tartaric acid is added to initiate gas production. This stepwise addition method effectively controls the gas production rate and the uniformity of bubbles, avoiding the local violent reaction and uneven bubble size caused by the simultaneous addition of the two reactants. At the same time, the aqueous phase medium required for the foaming reaction comes from the bound water introduced by the calcium chloride solution in step (2) and absorbed by the hydrophilic particles. No additional water is required. The acid-base reaction can be driven by the micro-domain aqueous phase distributed at the interface of the hydrophilic particles, thus realizing controllable foaming in the hot melt adhesive system.

[0017] 4. To address the problem of localized impact on the calcium alginate network caused by bubble expansion during foaming, leading to cross-linking fracture of the micropore walls and creating structural weaknesses, this invention introduces montmorillonite and polyvinyl alcohol (PVA) to form a synergistic reinforcing structure. First, PVA is intercalated and dispersed with montmorillonite, then spray-dried to prepare a pre-intercalated composite powder, which is added dry to avoid introducing excess moisture. During foaming, the montmorillonite / PVA composite powder acts as a rigid nanofiller dispersed in the micropore walls. During bubble expansion, the montmorillonite sheets exhibit a certain degree of preferential orientation along the stretching direction, and their high in-plane stiffness helps to hinder microcrack propagation and enhance the mechanical properties of the micropore walls. The dense hydroxyl groups on the PVA molecular chains form numerous hydrogen bonds with the silanol groups on the montmorillonite surface and the carboxyl groups in the calcium alginate gel, acting as molecular bridges to firmly connect the rigid montmorillonite sheets to the flexible gel matrix. This synergistic structure of rigid sheets and flexible bridging provides structural stiffness to resist deformation and ensures tight bonding at the interface. It effectively strengthens the microporous wall area and compensates for local stress defects caused by foaming, perfectly achieving the unity of high gel cohesion and high air permeability from both chemical and mechanical perspectives. Attached Figure Description

[0018] Figure 1 This is a low-magnification SEM image of the medical hydrocolloid dressing prepared in Example 1 of the present invention.

[0019] Figure 2This is a high-magnification SEM image of the medical hydrocolloid dressing prepared in Example 1 of the present invention. Detailed Implementation

[0020] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0021] Example 1 A method for preparing a medical hydrocolloid dressing includes the following steps: (1) By weight, 28 parts of styrene-isoprene-styrene block copolymer (SIS), 8 parts of rosin pentaerythritol ester and 0.9 parts of hindered phenolic antioxidant (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester) were added to a mixer and mixed for 20 min at 130°C and 100 r / min. Then, 18 parts of medical grade light liquid paraffin were added and mixed for another 10 min to form a uniform hot melt pressure-sensitive adhesive matrix. Then, the temperature was lowered to 95°C and 33 parts of sodium carboxymethyl cellulose (CMC-Na) and 9 parts of gelatin were added in sequence and mixed for another 10 min to obtain a hydrocolloid matrix premix.

[0022] (2) Take 5 parts of sodium alginate and add it directly to the hydrocolloid matrix premix obtained in step (1) in the internal mixer in dry powder form. Mix for 10 min at 90℃ and 100 r / min to make the sodium alginate powder uniformly dispersed in the matrix. Take another 2.5 parts of calcium chloride and dissolve it in deionized water to prepare a calcium chloride solution with a mass concentration of 13%. In the mixed state, add the calcium chloride solution to the internal mixer by atomization spraying and continue mixing for 20 min at 90℃ to make the Ca 2+ In-situ ionic crosslinking was carried out with hydrated sodium alginate to obtain a pre-crosslinked hydrocolloid mixture.

[0023] (3) Take 3 parts of sodium bicarbonate and 3 parts of L-tartaric acid, and grind them through a 200-mesh sieve. Take another 3 parts of pharmaceutical grade montmorillonite (particle size 1-10 μm) and 3 parts of polyvinyl alcohol (degree of alcoholysis 88%, degree of polymerization 1750). Add polyvinyl alcohol to deionized water and stir to dissolve at 90°C to prepare a 9% polyvinyl alcohol aqueous solution. Add montmorillonite to the above polyvinyl alcohol aqueous solution and stir at 400 r / min at 65°C and then treat with ultrasonic dispersion (power 300 W) for 25 min to obtain a montmorillonite / polyvinyl alcohol composite dispersion. Spray dry the composite dispersion (inlet temperature 165°C, outlet temperature 80°C) to obtain a montmorillonite / polyvinyl alcohol pre-intercalated composite powder. The internal mixer temperature was lowered to 55℃. Sodium bicarbonate powder was added to the pre-crosslinked hydrocolloid mixture obtained in step (2) and mixed for 4 minutes to ensure that the sodium bicarbonate particles were uniformly dispersed in the colloidal matrix. Then, L-tartaric acid powder and the above-mentioned montmorillonite / polyvinyl alcohol pre-intercalated composite powder were added simultaneously, and the mixture was continued to be mixed at 60℃ for 7 minutes. Sodium bicarbonate and tartaric acid reacted in the aqueous micro-domain of the matrix to release CO2 gas, forming a uniformly distributed microporous structure in situ inside the colloidal matrix. After the gas production was basically completed, the material was quickly transferred to a 100℃ flat vulcanizing machine for pressing and shaping for 8 minutes to fix the microporous structure and obtain a hydrocolloid sheet containing a microporous structure.

[0024] (4) The hydrocolloid sheet with microporous structure obtained in step (3) was placed in a vacuum drying oven at 55℃ and dried for 45 min (vacuum degree -0.085 MPa) to remove residual moisture introduced during the preparation process. The dried hydrocolloid sheet was then bonded to a polyurethane breathable film backing at 90℃ using a low-pressure hot-pressing composite method. The thickness of the colloid layer was 1.0 mm, and it was covered with medical release paper. After the finished product was sealed and packaged in a nitrogen atmosphere, it was sterilized by cobalt-60 irradiation (dose 22 kGy) and cut into 10cm×10cm specifications to obtain a high gel cohesive breathable medical hydrocolloid dressing.

[0025] Example 2 A method for preparing a medical hydrocolloid dressing includes the following steps: (1) By weight, 22 parts of styrene-isoprene-styrene block copolymer (SIS), 6 parts of rosin pentaerythritol ester and 0.5 parts of hindered phenolic antioxidant (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester) were added to a mixer and mixed for 20 min at 130°C and 100 r / min. Then, 18 parts of medical grade light liquid paraffin were added and mixed for another 10 min to form a uniform hot melt pressure-sensitive adhesive matrix. Then, the temperature was lowered to 95°C and 28 parts of sodium carboxymethyl cellulose (CMC-Na) and 6 parts of gelatin were added in sequence and mixed for another 10 min to obtain a hydrocolloid matrix premix.

[0026] (2) Take 5 parts of sodium alginate and add it directly to the hydrocolloid matrix premix obtained in step (1) in the internal mixer in dry powder form. Mix for 10 min at 90℃ and 100 r / min to make the sodium alginate powder uniformly dispersed in the matrix. Take another 1.5 parts of calcium chloride and dissolve it in deionized water to prepare a calcium chloride solution with a mass concentration of 11%. In the mixed state, add the calcium chloride solution to the internal mixer by atomization spraying and continue mixing for 20 min at 90℃ to make the Ca 2+ In-situ ionic crosslinking was carried out with hydrated sodium alginate to obtain a pre-crosslinked hydrocolloid mixture.

[0027] (3) Take 3 parts of sodium bicarbonate and 3 parts of L-tartaric acid, and grind them through a 200-mesh sieve. Take another 3 parts of pharmaceutical grade montmorillonite (particle size 1-10 μm) and 3 parts of polyvinyl alcohol (degree of alcoholysis 88%, degree of polymerization 1750). Add polyvinyl alcohol to deionized water and stir to dissolve at 90°C to prepare a 9% polyvinyl alcohol aqueous solution. Add montmorillonite to the above polyvinyl alcohol aqueous solution and stir at 400 r / min at 65°C and then treat with ultrasonic dispersion (power 300 W) for 25 min to obtain a montmorillonite / polyvinyl alcohol composite dispersion. Spray dry the composite dispersion (inlet temperature 165°C, outlet temperature 80°C) to obtain a montmorillonite / polyvinyl alcohol pre-intercalated composite powder. The internal mixer temperature was lowered to 55℃. Sodium bicarbonate powder was added to the pre-crosslinked hydrocolloid mixture obtained in step (2) and mixed for 4 minutes to ensure that the sodium bicarbonate particles were uniformly dispersed in the colloidal matrix. Then, L-tartaric acid powder and the above-mentioned montmorillonite / polyvinyl alcohol pre-intercalated composite powder were added simultaneously, and the mixture was continued to be mixed at 60℃ for 7 minutes. Sodium bicarbonate and tartaric acid reacted in the aqueous micro-domain of the matrix to release CO2 gas, forming a uniformly distributed microporous structure in situ inside the colloidal matrix. After the gas production was basically completed, the material was quickly transferred to a 100℃ flat vulcanizing machine for pressing and shaping for 8 minutes to fix the microporous structure and obtain a hydrocolloid sheet containing a microporous structure.

[0028] (4) The hydrocolloid sheet with microporous structure obtained in step (3) was placed in a vacuum drying oven at 55℃ and dried for 45 min (vacuum degree -0.085 MPa) to remove residual moisture introduced during the preparation process. The dried hydrocolloid sheet was then bonded to a polyurethane breathable film backing at 90℃ using a low-pressure hot-pressing composite method. The thickness of the colloid layer was 1.0 mm, and it was covered with medical release paper. After the finished product was sealed and packaged in a nitrogen atmosphere, it was sterilized by cobalt-60 irradiation (dose 22 kGy) and cut into 10cm×10cm specifications to obtain a high gel cohesive breathable medical hydrocolloid dressing.

[0029] Example 3 A method for preparing a medical hydrocolloid dressing includes the following steps: (1) By weight, 25 parts of styrene-isoprene-styrene block copolymer (SIS), 7 parts of rosin pentaerythritol ester and 0.7 parts of hindered phenolic antioxidant (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester) were added to a mixer and mixed for 20 min at 130°C and 100 r / min. Then, 18 parts of medical grade light liquid paraffin were added and mixed for another 10 min to form a uniform hot melt pressure-sensitive adhesive matrix. Then, the temperature was lowered to 95°C and 30 parts of sodium carboxymethyl cellulose (CMC-Na) and 7 parts of gelatin were added in sequence and mixed for another 10 min to obtain a hydrocolloid matrix premix.

[0030] (2) Take 5 parts of sodium alginate and add it directly to the hydrocolloid matrix premix obtained in step (1) in the internal mixer in dry powder form. Mix for 10 min at 90℃ and 100 r / min to make the sodium alginate powder uniformly dispersed in the matrix. Take another 2 parts of calcium chloride and dissolve it in deionized water to prepare a calcium chloride solution with a mass concentration of 12%. In the mixed state, add the calcium chloride solution to the internal mixer by atomization spraying and continue mixing for 20 min at 90℃ to make the Ca 2+ In-situ ionic crosslinking was carried out with hydrated sodium alginate to obtain a pre-crosslinked hydrocolloid mixture.

[0031] (3) Take 3 parts of sodium bicarbonate and 3 parts of L-tartaric acid, and grind them through a 200-mesh sieve. Take another 3 parts of pharmaceutical grade montmorillonite (particle size 1-10 μm) and 3 parts of polyvinyl alcohol (degree of alcoholysis 88%, degree of polymerization 1750). Add polyvinyl alcohol to deionized water and stir to dissolve at 90°C to prepare a 9% polyvinyl alcohol aqueous solution. Add montmorillonite to the above polyvinyl alcohol aqueous solution and stir at 400 r / min at 65°C and then treat with ultrasonic dispersion (power 300 W) for 25 min to obtain a montmorillonite / polyvinyl alcohol composite dispersion. Spray dry the composite dispersion (inlet temperature 165°C, outlet temperature 80°C) to obtain a montmorillonite / polyvinyl alcohol pre-intercalated composite powder. The internal mixer temperature was lowered to 55℃. Sodium bicarbonate powder was added to the pre-crosslinked hydrocolloid mixture obtained in step (2) and mixed for 4 minutes to ensure that the sodium bicarbonate particles were uniformly dispersed in the colloidal matrix. Then, L-tartaric acid powder and the above-mentioned montmorillonite / polyvinyl alcohol pre-intercalated composite powder were added simultaneously, and the mixture was continued to be mixed at 60℃ for 7 minutes. Sodium bicarbonate and tartaric acid reacted in the aqueous micro-domain of the matrix to release CO2 gas, forming a uniformly distributed microporous structure in situ inside the colloidal matrix. After the gas production was basically completed, the material was quickly transferred to a 100℃ flat vulcanizing machine for pressing and shaping for 8 minutes to fix the microporous structure and obtain a hydrocolloid sheet containing a microporous structure.

[0032] (4) The hydrocolloid sheet with microporous structure obtained in step (3) was placed in a vacuum drying oven at 55℃ and dried for 45 min (vacuum degree -0.085 MPa) to remove residual moisture introduced during the preparation process. The dried hydrocolloid sheet was then bonded to a polyurethane breathable film backing at 90℃ using a low-pressure hot-pressing composite method. The thickness of the colloid layer was 1.0 mm, and it was covered with medical release paper. After the finished product was sealed and packaged in a nitrogen atmosphere, it was sterilized by cobalt-60 irradiation (dose 22 kGy) and cut into 10cm×10cm specifications to obtain a high gel cohesive breathable medical hydrocolloid dressing.

[0033] Example 4 A method for preparing a medical hydrocolloid dressing includes the following steps: (1) By weight, 30 parts of styrene-isoprene-styrene block copolymer (SIS), 10 parts of rosin pentaerythritol ester and 1 part of hindered phenolic antioxidant (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester) were added to a mixer and mixed for 25 min at 140°C and 100 r / min. Then, 18 parts of medical grade light liquid paraffin were added and mixed for another 10 min to form a uniform hot melt pressure-sensitive adhesive matrix. Then, the temperature was lowered to 100°C and 35 parts of sodium carboxymethyl cellulose (CMC-Na) and 10 parts of gelatin were added in sequence and mixed for another 15 min to obtain a hydrocolloid matrix premix.

[0034] (2) Take 5 parts of sodium alginate and add it directly to the hydrocolloid matrix premix obtained in step (1) in the internal mixer in dry powder form. Mix for 12 minutes at 100℃ and 100r / min to make the sodium alginate powder uniformly dispersed in the matrix. Take another 3 parts of calcium chloride and dissolve it in deionized water to prepare a calcium chloride solution with a mass concentration of 15%. In the mixed state, add the calcium chloride solution to the internal mixer by atomization spraying and continue mixing for 25 minutes at 100℃ to make the Ca 2+ In-situ ionic crosslinking was carried out with hydrated sodium alginate to obtain a pre-crosslinked hydrocolloid mixture.

[0035] (3) Take 3 parts sodium bicarbonate and 3 parts L-tartaric acid, and grind them through a 200-mesh sieve. Take another 3 parts pharmaceutical grade montmorillonite (particle size 1-10 μm) and 3 parts polyvinyl alcohol (degree of alcoholysis 88%, degree of polymerization 1750). Add polyvinyl alcohol to deionized water and stir to dissolve at 90°C to prepare a 9% polyvinyl alcohol aqueous solution. Add montmorillonite to the above polyvinyl alcohol aqueous solution and stir at 400 r / min at 70°C and then treat with ultrasonic dispersion (power 300 W) for 25 min to obtain a montmorillonite / polyvinyl alcohol composite dispersion. Spray dry the composite dispersion (inlet temperature 165°C, outlet temperature 80°C) to obtain a montmorillonite / polyvinyl alcohol pre-intercalated composite powder. The internal mixer temperature was lowered to 60°C. Sodium bicarbonate powder was added to the pre-crosslinked hydrocolloid mixture obtained in step (2) and mixed for 5 minutes to ensure that the sodium bicarbonate particles were uniformly dispersed in the colloidal matrix. Then, L-tartaric acid powder and the above-mentioned montmorillonite / polyvinyl alcohol pre-intercalated composite powder were added simultaneously, and the mixture was continued to be mixed for 8 minutes at 70°C. Sodium bicarbonate and tartaric acid reacted in the aqueous micro-domain of the matrix to release CO2 gas, forming a uniformly distributed microporous structure in situ inside the colloidal matrix. After the gas production was basically completed, the material was quickly transferred to a 105°C flat vulcanizing machine for pressing and shaping for 10 minutes to fix the microporous structure and obtain a hydrocolloid sheet containing a microporous structure.

[0036] (4) The hydrocolloid sheet with microporous structure obtained in step (3) was placed in a vacuum drying oven at 55℃ and dried for 45 min (vacuum degree -0.085 MPa) to remove residual moisture introduced during the preparation process. The dried hydrocolloid sheet was then bonded to a polyurethane breathable film backing at 90℃ using a low-pressure hot-pressing composite method. The thickness of the colloid layer was 1.0 mm, and it was covered with medical release paper. After the finished product was sealed and packaged in a nitrogen atmosphere, it was sterilized by cobalt-60 irradiation (dose 22 kGy) and cut into 10cm×10cm specifications to obtain a high gel cohesive breathable medical hydrocolloid dressing.

[0037] Example 5 A method for preparing a medical hydrocolloid dressing includes the following steps: (1) By weight, 20 parts of styrene-isoprene-styrene block copolymer (SIS), 5 parts of rosin pentaerythritol ester and 0.3 parts of hindered phenolic antioxidant (tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate] pentaerythritol ester) were added to a mixer and mixed for 15 min at 120°C and 100 r / min. Then, 18 parts of medical grade light liquid paraffin were added and mixed for another 10 min to form a uniform hot melt pressure-sensitive adhesive matrix. Then, the temperature was lowered to 90°C and 25 parts of sodium carboxymethyl cellulose (CMC-Na) and 5 parts of gelatin were added in sequence and mixed for another 8 min to obtain a hydrocolloid matrix premix.

[0038] (2) Take 5 parts of sodium alginate and add it directly to the hydrocolloid matrix premix obtained in step (1) in the internal mixer in dry powder form. Mix for 8 minutes at 80°C and 100 r / min to ensure that the sodium alginate powder is evenly dispersed in the matrix. Take another 1 part of calcium chloride and dissolve it in deionized water to prepare a calcium chloride solution with a mass concentration of 10%. In the mixed state, add the calcium chloride solution to the internal mixer by atomization spraying and continue mixing for 15 minutes at 80°C to ensure that the calcium chloride solution is evenly dispersed in the matrix. 2+ In-situ ionic crosslinking was carried out with hydrated sodium alginate to obtain a pre-crosslinked hydrocolloid mixture.

[0039] (3) Take 3 parts sodium bicarbonate and 3 parts L-tartaric acid, and grind them through a 200-mesh sieve. Take another 3 parts pharmaceutical grade montmorillonite (particle size 1-10 μm) and 3 parts polyvinyl alcohol (degree of alcoholysis 88%, degree of polymerization 1750). Add polyvinyl alcohol to deionized water and stir to dissolve at 90°C to prepare a 9% polyvinyl alcohol aqueous solution. Add montmorillonite to the above polyvinyl alcohol aqueous solution and stir at 400 r / min at 60°C and then treat with ultrasonic dispersion (power 300 W) for 25 min to obtain a montmorillonite / polyvinyl alcohol composite dispersion. Spray dry the composite dispersion (inlet temperature 165°C, outlet temperature 80°C) to obtain a montmorillonite / polyvinyl alcohol pre-intercalated composite powder. The internal mixer temperature was lowered to 50°C. Sodium bicarbonate powder was added to the pre-crosslinked hydrocolloid mixture obtained in step (2) and mixed for 3 minutes to ensure that the sodium bicarbonate particles were uniformly dispersed in the colloidal matrix. Then, L-tartaric acid powder and the above-mentioned montmorillonite / polyvinyl alcohol pre-intercalated composite powder were added simultaneously, and the mixture was continued to be mixed for 5 minutes at 55°C. Sodium bicarbonate and tartaric acid reacted in the aqueous micro-domain of the matrix to release CO2 gas, forming a uniformly distributed microporous structure in situ inside the colloidal matrix. After the gas production was basically completed, the material was quickly transferred to a 90°C flat vulcanizing machine for pressing and shaping for 5 minutes to fix the microporous structure and obtain a hydrocolloid sheet containing a microporous structure.

[0040] (4) The hydrocolloid sheet with microporous structure obtained in step (3) was placed in a vacuum drying oven at 55℃ and dried for 45 min (vacuum degree -0.085 MPa) to remove residual moisture introduced during the preparation process. The dried hydrocolloid sheet was then bonded to a polyurethane breathable film backing at 90℃ using a low-pressure hot-pressing composite method. The thickness of the colloid layer was 1.0 mm, and it was covered with medical release paper. After the finished product was sealed and packaged in a nitrogen atmosphere, it was sterilized by cobalt-60 irradiation (dose 22 kGy) and cut into 10cm×10cm specifications to obtain a high gel cohesive breathable medical hydrocolloid dressing.

[0041] Comparative Example 1: Compared with Example 4, sodium alginate and calcium chloride were not added in step (2) (i.e., no ionic crosslinking modification was performed), and the remaining steps and parameters were exactly the same as in Example 4.

[0042] Comparative Example 2: Compared with Example 4, sodium bicarbonate and L-tartaric acid were not added in step (3) (i.e., in-situ foaming was not performed), and the remaining steps and parameters were exactly the same as in Example 4.

[0043] Comparative Example 3: Compared with Example 4, montmorillonite / polyvinyl alcohol pre-intercalated composite powder was not added in step (3) (i.e., no micropore wall interface reinforcement was performed), and the remaining steps and parameters were exactly the same as in Example 4.

[0044] Comparative Example 4: Compared with Example 4, in step (3), an equal amount of citric acid was used to replace L-tartaric acid as the gas-producing acid source, and the remaining steps and parameters were exactly the same as in Example 4.

[0045] Comparative Example 5: Compared with Example 4, only 3 parts of montmorillonite dry powder were added in step (3) without the addition of polyvinyl alcohol (i.e., montmorillonite without intercalation treatment was added directly), and the remaining steps and parameters were exactly the same as in Example 4.

[0046] Comparative Example 6: Compared with Example 4, only 3 parts of polyvinyl alcohol dry powder were added in step (3) without the addition of montmorillonite (i.e. only flexible bridging without rigid sheet reinforcement), and the remaining steps and parameters were exactly the same as in Example 4.

[0047] Comparative Example 7: Compared with Example 4, no hindered phenolic antioxidant was added in step (1), and the remaining steps and parameters were exactly the same as in Example 4.

[0048] Comparative Example 8: Compared with Example 4, in step (3), the montmorillonite / polyvinyl alcohol composite dispersion was added directly to the internal mixer in the form of liquid dispersion without spray drying. The remaining steps and parameters were exactly the same as in Example 4.

[0049] Comparative Example 9: Compared with Example 4, in step (3), sodium bicarbonate and L-tartaric acid were added to the internal mixer at the same time (i.e., the step feeding method was not adopted), and the remaining steps and parameters were exactly the same as in Example 4.

[0050] Comparative Example 10: Compared with Example 4, in step (2), the calcium chloride solution was added to the internal mixer in a one-time pouring manner (i.e., the atomized spraying method was not used), and the remaining steps and parameters were exactly the same as in Example 4.

[0051] Performance testing 1. Liquid Absorption Test: The hydrocolloid dressings prepared in each example and comparative example were cut into 5cm × 5cm square samples. After weighing the dry mass (m0), the samples were immersed in type A simulated body fluid (8.298g NaCl + 0.368g CaCl2·2H2O dissolved in 1000mL deionized water) at 37±1℃ for 24h. After soaking, the samples were removed, held vertically with tweezers for 30s to drain excess liquid, and the wet mass (m1) was weighed. The liquid absorption was calculated using the formula: Liquid Absorption = (m1 - m0) / Sample Area (g / 100cm²). 2 ) Calculate, and take the average value of 5 parallel samples in each group.

[0052] 2. Water vapor transmission rate (MVTR) test: Cover each sample with a standard permeation cup (33mm diameter) containing 20mL of distilled water, maintaining a distance of approximately 10mm between the liquid level and the sample. Place the permeation cup containing the sample in a constant temperature and humidity chamber at 37±1℃ and 20±5% relative humidity. Record the initial mass and let it stand for 24 hours. Weigh the final mass and calculate the water vapor transmission rate (g / m³) using the formula MVTR=Δm / (A×t). 2 / 24h), where Δm is the mass loss (g), and A is the test area (m²). 2 ), t is time (days), and 3 parallel samples are taken from each group and the average value is taken.

[0053] 3. Gel Cohesion (Gel Residue Rating) Test: Each sample was cut into 5cm × 5cm pieces and attached to a clean stainless steel plate surface. The samples were then immersed in type A simulated body fluid at 37±1℃ for 24 hours to allow the hydrocolloid to fully absorb the liquid and swell, forming a gel layer. The dressing was then removed at a uniform speed in a 180° direction. The gel residue on the stainless steel plate surface was observed and rated: Grade 0 was no residue; Grade 1 was a very small amount of dotted residue (residual area < 5%); Grade 2 was a small amount of patchy residue (residual area 5%–25%); Grade 3 was significant large-area residue (residual area > 25%); and Grade 4 was gel disintegration and detachment. Five parallel samples were taken from each group, and the rating that occurred most frequently was used as the final rating for that sample.

[0054] 4. 180° Peel Strength Test: Cut each sample into strips 25mm wide and 150mm long. Under standard environmental conditions of 23±2℃ and 50±5%RH, adhere the sample to the surface of a clean stainless steel plate and roll it once back and forth at a speed of 300mm / min using a 2kg standard pressure roller. After 20 minutes, fix the stainless steel plate on the lower clamp of the universal testing machine, fold the free end of the sample 180° and clamp it in the upper clamp, and peel it at a uniform speed of 300mm / min. Record the average peel force and calculate it using the formula 180° peel strength = F / b (N / 25mm), where F is the average peel force (N) and b is the sample width (25mm). Take 5 parallel samples from each group and take the average value.

[0055] 5. Tensile Strength Test After Gel Swelling: Each specimen was cut into dumbbell-shaped standard specimens (effective section width 10 mm, gauge length 20 mm). After being fully swollen by immersing in type A simulated body fluid at 37±1℃ for 24 hours, a tensile test was immediately performed using a universal testing machine at a tensile rate of 50 mm / min. The maximum tensile strength was recorded and converted into tensile strength (MPa). Five parallel samples were taken from each group, and the average value was calculated. This test reflects the mechanical integrity of the gel after liquid absorption; a higher tensile strength indicates stronger gel cohesion.

[0056] Table 1: Comparative Example 1 (without ionic crosslinking): Liquid absorption and air permeability were similar to Example 4, but the gel residue rating dropped to level 3 (large-area residue), and the tensile strength after swelling was only 0.042 MPa (30% of Example 4), indicating that the gel cohesion was severely insufficient due to the lack of alginate calcium ionic crosslinking network. Comparative Example 2 (without foaming): Excellent gel cohesion (level 0 residue, tensile strength 0.141 MPa), but water vapor transmission rate was only 385 g / m³. 2The results of 24h (54% of Example 4) confirmed the crucial role of microporous structure in air permeability. Comparative Example 3 (without montmorillonite / PVA reinforcement): Air permeability was similar to Example 4, but gel residue increased to grade 2, and tensile strength after swelling decreased to 0.071 MPa (51% of Example 4), indicating that the lack of microporous wall reinforcement significantly negatively impacted gel cohesion during foaming. Comparative Example 4 (citric acid instead of tartaric acid): Gel residue increased to grade 2, and tensile strength after swelling decreased to 0.068 MPa (49% of Example 4), confirming the chelating and destructive effect of sodium citrate byproducts on the calcium alginate eggshell network. Comparative Examples 5 and 6 (montmorillonite and PVA used alone): Performance was between Comparative Example 3 (neither added) and Example 4 (synergistic use), confirming that the synergistic reinforcing effect of montmorillonite and PVA is superior to either single component. Comparative Example 7 (without antioxidant): The 180° peel strength decreased from 3.1 to 1.6 N / 25 mm (a decrease of 48%), indicating that SIS underwent significant thermal oxidative degradation during multi-step high-temperature processing and irradiation sterilization, leading to a substantial decline in adhesive performance. Comparative Example 8 (without spray drying): Liquid absorption decreased to 2.74 g / 100 cm³. 2 The water vapor transmission rate decreased to 558 g / m 2 The 24-hour timeframe indicates that the introduction of a large amount of moisture interfered with the processing uniformity and foaming effect of the hot melt adhesive matrix. Comparative Example 9 (NaHCO3 and tartaric acid added simultaneously): water vapor transmission rate decreased to 643 g / m³. 2 The 24h time (approximately 10% lower than in Example 4) indicates that the lack of stepwise feeding leads to uneven gas production, uneven bubble distribution, and decreased foaming efficiency and micropore uniformity. Comparative Example 10 (CaCl2 poured out in one go): the gel residue level increased from 0 to 1, and the tensile strength after swelling decreased to 0.096 MPa (30% lower than in Example 4), indicating that the non-atomization method resulted in uneven calcium ion distribution, local over-crosslinking, and local under-crosslinking, which reduced the overall gel cohesion.

[0057] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the essence and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a medical hydrocolloid dressing, characterized in that, Includes the following steps: (1) The thermoplastic elastomer and the tackifying resin are mixed and melted, and then hydrophilic polymer particles are added and mixed evenly to obtain a hydrocolloid matrix premix. (2) Add alginate powder to the hydrocolloid matrix premix for dispersion, and then atomize and add soluble calcium salt solution to make alginate and calcium ions undergo in-situ ionic cross-linking to obtain a pre-cross-linked hydrocolloid mixture; (3) Add a foaming agent, a gas-producing acid and a layered silicate / water-soluble polymer pre-intercalation composite powder to the pre-crosslinked hydrocolloid mixture and mix them so that the foaming agent and the gas-producing acid react to produce gas and foam in situ inside the matrix to form a microporous structure. Then, perform hot pressing to shape and obtain a hydrocolloid sheet with a microporous structure. (4) The hydrocolloid sheet is dried and then hot-pressed with a breathable film backing to obtain the final product.

2. The method for preparing a medical hydrocolloid dressing according to claim 1, characterized in that, The thermoplastic elastomer mentioned in step (1) is a styrene-isoprene-styrene block copolymer; The tackifying resin is pentaerythritol rosin; The hydrophilic polymer particles are a mixture of sodium carboxymethyl cellulose and gelatin.

3. The method for preparing a medical hydrocolloid dressing according to claim 2, characterized in that, In step (1), a hindered phenolic antioxidant is also added when mixing and melting the thermoplastic elastomer and the tackifying resin.

4. The method for preparing a medical hydrocolloid dressing according to claim 3, characterized in that, The specific operation steps for step (1) are as follows: First, 20-30 parts by weight of the thermoplastic elastomer, 5-10 parts by weight of the tackifying resin and 0.3-1 parts by weight of the hindered phenolic antioxidant are mixed at 120-140°C for 15-25 minutes to form a hot melt pressure-sensitive adhesive matrix. Then, the temperature is lowered to 90-100°C, and the hydrophilic polymer particles are added and the mixture is continued to be mixed for 8-15 minutes. The hydrophilic polymer particles include 25-35 parts by weight of sodium carboxymethyl cellulose and 5-10 parts by weight of gelatin.

5. The method for preparing a medical hydrocolloid dressing according to claim 1, characterized in that, The alginate mentioned in step (2) is sodium alginate; The soluble calcium salt is calcium chloride; Preferably, the sodium alginate is added to the hydrocolloid matrix premix in dry powder form at 80-100°C and mixed for 8-12 minutes; the calcium chloride is dissolved in deionized water to prepare a calcium chloride solution with a mass concentration of 10%-15%, and the calcium chloride solution is added by atomization spraying while the mixture is in a mixed state, and mixing is continued at 80-100°C for 15-25 minutes.

6. The method for preparing a medical hydrocolloid dressing according to claim 5, characterized in that, The mass ratio of sodium alginate to calcium chloride is 5:(1-3).

7. The method for preparing a medical hydrocolloid dressing according to claim 5, characterized in that, The foaming agent mentioned in step (3) is sodium bicarbonate; The gas-producing acid is L-tartaric acid; The specific steps of step S3 are as follows: First, add the sodium bicarbonate to the pre-crosslinked hydrocolloid mixture at 50-60°C and mix for 3-5 minutes. Then, add the L-tartaric acid and the layered silicate / water-soluble polymer pre-intercalation composite powder and continue mixing at 55-70°C for 5-8 minutes to initiate a foaming reaction. After the gas generation is basically completed, quickly transfer the material to a flat vulcanizing machine at 90-105°C for pressing and shaping for 5-10 minutes.

8. A method for preparing a medical hydrocolloid dressing according to claim 1 or 7, characterized in that, The preparation method of the layered silicate / water-soluble polymer pre-intercalated composite powder is as follows: Polyvinyl alcohol is added to water and stirred to dissolve, thus preparing a polyvinyl alcohol aqueous solution; Montmorillonite was added to the polyvinyl alcohol aqueous solution, stirred at 60-70°C and subjected to ultrasonic dispersion treatment to allow the montmorillonite sheets to be intercalated and dispersed in the polyvinyl alcohol solution, thus obtaining a montmorillonite / polyvinyl alcohol composite dispersion. The composite dispersion was spray-dried to obtain the montmorillonite / polyvinyl alcohol pre-intercalated composite powder.

9. The method for preparing a medical hydrocolloid dressing according to claim 1, characterized in that, Step (4) also includes sealing and packaging the hot-pressed composite product in a nitrogen atmosphere and subjecting it to irradiation sterilization.

10. A medical aqueous colloidal dressing, characterized in that, It is prepared by the method described in any one of claims 1 to 9 above.

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