A highly absorbent hydrocolloid dressing and method of making same

Abstract

The application relates to the field of medical dressing technology and particularly relates to a high-absorptive hydrogel dressing and a preparation method thereof, which comprises a substrate layer, a release layer and a hydrogel layer arranged between the substrate layer and the release layer; the hydrogel layer comprises the following raw materials in parts by weight: hot melt adhesive 55-65 parts, polyisobutylene 5-10 parts, CMC 20-30 parts, crosslinked CMC 1-3 parts and calcium alginate 3-8 parts. The application adopts a composite system of CMC and crosslinked CMC, CMC can quickly absorb wound exudate and form a gel, crosslinked CMC has a three-dimensional network structure and is helpful to enhancing the stability of the hydrogel network, and then calcium alginate is added, can cooperate with CMC to further absorb a large amount of wound exudate, calcium alginate itself has good gel-forming property, can form a moist gel layer at a wound, thereby cooperating with CMC and crosslinked CMC to reduce the probability of liquid diffusion to the surroundings, so that the hydrogel dressing with high absorbency is prepared.

Description

Technical Field

[0001] This application relates to the field of medical dressing technology, and in particular to a highly absorbent hydrocolloid dressing and a method for preparing the same. Background Technology

[0002] Hydrocolloid dressings, due to their excellent biocompatibility, gentle adhesion, and ability to create a moist healing environment, have been widely used in the clinical care of chronic wounds and mildly exudative wounds. Their traditional formulations typically consist of sodium carboxymethyl cellulose, a thickener, and an elastomer matrix. Sodium carboxymethyl cellulose absorbs water and swells to form a gel, providing a moist healing environment for the wound.

[0003] However, existing hydrocolloid dressings generally suffer from insufficient absorbency. On the one hand, although the traditional sodium carboxymethyl cellulose component has a certain degree of hygroscopicity, its absorption rate is slow, making it difficult to cope with the large amount of exudate generated in a short time in highly exudative wounds. This can easily lead to the accumulation of exudate around the wound, causing maceration dermatitis. On the other hand, as the sodium carboxymethyl cellulose becomes saturated, the gel layer on the surface of the dressing will quickly seal off, blocking the channels for further migration of exudate into the dressing. This results in a shortened effective lifespan of the dressing, increasing the frequency of dressing changes and patient discomfort.

[0004] In response to the aforementioned technologies, the inventors have provided a highly absorbent hydrocolloid dressing and its preparation method. Summary of the Invention

[0005] To improve the absorbency of hydrocolloid dressings, this application provides a highly absorbent hydrocolloid dressing and a method for preparing the same.

[0006] In a first aspect, this application provides a highly absorbent hydrocolloid dressing, which adopts the following technical solution: A highly absorbent hydrocolloid dressing includes a substrate layer, a release layer, and a hydrocolloid layer disposed between the substrate layer and the release layer; the hydrocolloid layer comprises the following raw materials in parts by weight: 55-65 parts hot melt adhesive, 5-10 parts polyisobutylene, 20-30 parts CMC, 1-3 parts crosslinked CMC, and 3-8 parts calcium alginate.

[0007] By adopting the above technical solution, the hot melt adhesive, as the main body, works synergistically with polyisobutylene to ensure the initial adhesion of the hydrocolloid dressing to the skin. Furthermore, the addition of a composite system of CMC and cross-linked CMC, where CMC, as the main hydrophilic material, can quickly absorb wound exudate and form a gel, and the cross-linked CMC has a three-dimensional network structure that helps enhance the stability of the hydrocolloid network, allowing it to hold more exudate and reducing the probability of excessive expansion, deformation, or disintegration of the hydrocolloid dressing after absorbing liquid, thus significantly increasing its absorbency. The addition of calcium alginate, with its strong ion exchange and liquid absorption capabilities, further enhances the absorption of large amounts of wound exudate in conjunction with CMC. Calcium alginate itself has good gelling properties, forming a moist gel layer at the wound site, thus synergistically reducing the probability of liquid diffusion with CMC and cross-linked CMC, resulting in a highly absorbent hydrocolloid dressing.

[0008] This application employs a composite system of CMC and cross-linked CMC. CMC can rapidly absorb wound exudate and form a gel, while cross-linked CMC has a three-dimensional network structure, which helps to enhance the stability of the hydrocolloid network. Furthermore, the addition of calcium alginate can work with CMC to further absorb a large amount of wound exudate. Calcium alginate itself has good gelling properties and will form a moist gel layer at the wound site, thereby synergistically reducing the probability of liquid spreading to the surrounding area with CMC and cross-linked CMC, thus producing a highly absorbent hydrocolloid dressing.

[0009] Preferably, the preparation method of the cross-linked CMC includes the following steps: adjusting the pH of the aluminum citrate solution to 6-7, adding CMC to the aluminum citrate solution, mixing evenly, adding gluconate-δ-lactone, stirring evenly, and allowing it to stand to obtain cross-linked CMC.

[0010] By adopting the above technical solution and using aluminum citrate as a crosslinking agent, the pH value of the aluminum citrate solution is first adjusted to 6-7. At this time, aluminum ions are in a relatively stable complexed or aluminum hydroxide micronucleus state, and the reactivity is temporarily inhibited. Then, CMC and gluconate-δ-lactone are added. Gluconate-δ-lactone will slowly hydrolyze in water to generate gluconate, so that the pH value of the system decreases uniformly and slowly. As the pH decreases, the complexing ability of citrate ions on aluminum ions weakens, so that aluminum ions are gradually and gently released and undergo a slow and uniform crosslinking reaction with the carboxyl groups on the CMC molecular chain to form a uniform and dense three-dimensional network gel that can bind a large amount of liquid.

[0011] Preferably, the degree of substitution of the CMC is 0.7-1.2.

[0012] By adopting the above technical solution, when the substitution of CMC is too low, the number of carboxyl groups on CMC that can be crosslinked by aluminum ions is reduced. This not only leads to a decrease in the solubility of CMC in water, but also results in a sparse three-dimensional network structure with low crosslinking density. After absorbing liquid, it is easy to break and disintegrate, which significantly reduces the absorbency of the hydrocolloid dressing to exudate.

[0013] When the substitution of CMC is too high, it may make CMC too hydrophilic, resulting in extremely high solution viscosity. This makes it difficult to mix uniformly with aluminum citrate and glucono-δ-lactone during the preparation of crosslinked CMC. In addition, too many carboxyl sites will lead to excessively dense crosslinking points. As the pH of the system decreases, it will react violently with aluminum ions, resulting in excessive local crosslinking and a decrease in the absorbency of the hydrocolloid dressing.

[0014] Preferably, the mass ratio of aluminum citrate to CMC is 1:15-35.

[0015] By adopting the above technical solution, when the amount of aluminum citrate added is too high, it will lead to excessive cross-linking, causing the CMC molecular chains to be over-coiled and rigid, making it difficult to swell fully after absorbing water, resulting in a significant decrease in the liquid absorption of the hydrocolloid dressing; when the amount of aluminum citrate added is too low, the cross-linking agent is insufficient, resulting in a low cross-linking density. The resulting cross-linked CMC still has high water solubility and cannot form a strong gel network after absorbing water, thus failing to provide skeletal support and function.

[0016] Preferably, the calcium alginate is acrylamide-grafted calcium alginate.

[0017] By adopting the above technical solution, the introduction of acrylamide is equivalent to introducing a large number of additional hydrophilic groups, which significantly improves its ability to absorb exudate compared to ordinary calcium alginate. Furthermore, calcium alginate can form a rigid network through ionic cross-linking, providing basic skeletal support, while the long polymer chains formed by acrylamide grafting can form a flexible network through covalent cross-linking. The two networks may form interpenetrating or semi-interpenetrating network structures. The gel formed by this dual network not only has a larger liquid absorption capacity but also better strength, elasticity, and toughness, making it less prone to breakage or loss after absorbing large amounts of liquid.

[0018] When the crosslinked CMC is aluminum citrate crosslinked CMC, the crosslinked CMC acts as a stable water-locking framework, while acrylamide-grafted calcium alginate acts as a water-absorbing unit. The two work synergistically to form an interpenetrating or semi-interpenetrating polymer network, together creating a highly absorbent composite gel. Furthermore, the aluminum ions in the aluminum citrate crosslinked CMC and the calcium ions in the acrylamide-grafted calcium alginate may simultaneously interact with negatively charged groups such as carboxyl groups, forming a more complex "mixed ionic crosslinking" network, further enhancing the gel's mechanical stability.

[0019] Preferably, it also contains polydopamine.

[0020] By employing the above-mentioned technical solution, polydopamine, rich in catechol groups, can strongly interact with various groups on the tissue surface through covalent and non-covalent bonds, thereby achieving a close adhesion of the hydrocolloid dressing to the skin around the wound. Polydopamine also possesses broad-spectrum antibacterial properties, inhibiting bacterial growth through contact or slow release of active substances, thus reducing the risk of wound infection. Furthermore, polydopamine can effectively scavenge excess reactive oxygen species at the wound site, reducing oxidative stress and creating a more favorable microenvironment for cell healing.

[0021] In addition, polydopamine can form strong hydrogen bonds and π-π stacking interactions with the polyacrylamide segments on acrylamide-grafted calcium alginate, forming a denser hybrid interpenetrating network with the existing cross-linked network in the system. Polydopamine can also chelate calcium ions released by calcium alginate through catechol groups, thereby further strengthening the "egg-box structure" cross-linking of calcium alginate and significantly improving the flexibility of hydrocolloid dressings.

[0022] Simultaneously, the addition of polydopamine can also form catechol-Al with unsaturated aluminum ions coordinated on free or cross-linked CMCs in the system. 3+ Coordination bond, catechol-Al 3+ Coordination bonds are dynamic and reversible, and can also serve as additional physical crosslinking points to connect the crosslinked CMC network more tightly, thereby significantly enhancing the mechanical strength of hydrocolloid dressings, making them more resistant to compression and less prone to collapse.

[0023] Preferably, the mass ratio of the acrylamide-grafted calcium alginate to polydopamine is 1:0.05-0.2.

[0024] By adopting the above technical solution, when the proportion of acrylamide-grafted calcium alginate is too high, the amount of polydopamine added is insufficient, which leads to a decrease in the adhesion between the hydrocolloid dressing and the skin around the wound. Furthermore, when there is too little polydopamine, the π-π stacking and hydrogen bonding between polydopamine and polyacrylamide segments are reduced, which weakens the synergistic enhancement effect between the cross-linked networks in the system.

[0025] When the proportion of acrylamide-grafted calcium alginate is too low, excessive polydopamine may over-crosslink or occupy the gel network space, inhibiting the rapid swelling and high liquid absorption capacity of acrylamide-grafted calcium alginate, resulting in a significant decrease in the liquid absorption of the hydrocolloid dressing. Furthermore, insufficient addition of acrylamide-grafted calcium alginate will lead to a lack of ideal mechanical support in the system, resulting in a loose overall structure and decreased cohesion.

[0026] Secondly, this application provides a method for preparing a highly absorbent hydrocolloid dressing, which employs the following technical solution: A method for preparing a highly absorbent hydrocolloid dressing includes the following steps: S1. Melt the hot melt adhesive according to the formula to obtain hot melt adhesive melt; S2. Add the formulated amount of polyisobutylene to the hot melt adhesive melt, mix evenly, then add the formulated amount of CMC and cross-linked CMC, rotate and knead, then add calcium alginate, knead and discharge to obtain the water adhesive layer. S3. Apply the water-based adhesive layer onto the substrate layer, and after cooling, cover the other side of the water-based adhesive layer with a release layer to obtain a highly absorbent hydrocolloid dressing.

[0027] By adopting the above technical solution, hot melt adhesive is first melted, and then polyisobutylene, CMC, cross-linked CMC and calcium alginate are uniformly mixed with the molten hot melt adhesive using distributed feeding and rotary kneading to obtain a water-based adhesive layer. Then, a substrate layer and a release layer are covered on both sides of the water-based adhesive layer to obtain a high-absorbency hydrocolloid dressing with ideal performance.

[0028] Preferably, in step S2, after adding the prescribed amount of polydopamine and calcium alginate and mixing, the mixture is kneaded and discharged to obtain a hydrogel layer.

[0029] By adopting the above technical solution, adding polydopamine and calcium alginate to S2 helps to achieve rapid chelation between the catechol of polydopamine and the calcium ions on the surface of calcium alginate. This allows polydopamine to form a uniform coating layer on the surface of calcium alginate, which not only protects the calcium alginate molecular chains from excessive thermal oxidation during subsequent kneading, but also crosslinks with the calcium ions released by calcium alginate, achieving synergistic cooperation with calcium alginate.

[0030] Preferably, the melting temperature of the hot melt adhesive is 100-120°C.

[0031] By adopting the above technical solution, when the melting temperature is too high, the excessive temperature may cause CMC to dehydrate and coke, reducing its hydration capacity and swelling properties. At the same time, it will destroy the gel structure of sodium alginate, resulting in a significant decrease in the liquid absorption capacity of the hydrocolloid dressing. When the melting temperature is too low, the hot melt adhesive cannot be completely melted into a uniform melt, resulting in the subsequent addition of raw materials not being evenly dispersed, which degrades the performance of the resulting hydrocolloid dressing.

[0032] In summary, this application includes at least one of the following beneficial technical effects: 1. This application utilizes a composite system of CMC and cross-linked CMC. CMC can rapidly absorb wound exudate and form a gel. Cross-linked CMC has a three-dimensional network structure, which helps to enhance the stability of the hydrocolloid network. Furthermore, the addition of calcium alginate can work with CMC to further absorb a large amount of wound exudate. Calcium alginate itself has good gelling properties and will form a moist gel layer at the wound site, thereby synergistically reducing the probability of liquid spreading to the surrounding area with CMC and cross-linked CMC, thus producing a highly absorbent hydrocolloid dressing. 2. This application uses aluminum citrate as a crosslinking agent. First, the pH value of the aluminum citrate solution is adjusted to 6-7. At this time, aluminum ions are in a relatively stable complexed or aluminum hydroxide micronucleus state, and the reactivity is temporarily inhibited. Then, CMC and gluconate-δ-lactone are added. Gluconate-δ-lactone will slowly hydrolyze in water to generate gluconate, so that the pH value of the system decreases uniformly and slowly. As the pH decreases, the complexing ability of citrate ions on aluminum ions weakens, so that aluminum ions are gradually and gently released and undergo a slow and uniform crosslinking reaction with the carboxyl groups on the CMC molecular chain to form a uniform and dense three-dimensional network gel that can bind a large amount of liquid. 3. This application utilizes acrylamide-grafted calcium alginate. The introduction of acrylamide is equivalent to introducing a large number of additional hydrophilic groups, significantly improving its exudate absorption capacity compared to ordinary calcium alginate. Furthermore, calcium alginate can form a rigid network through ionic cross-linking, providing basic skeletal support, while the long polymer chains formed by acrylamide grafting can form a flexible network through covalent cross-linking. The two networks may form interpenetrating or semi-interpenetrating network structures. This dual-network gel not only has a larger liquid absorption capacity but also better strength, elasticity, and toughness, making it less prone to breakage or loss after absorbing a large amount of liquid. Attached Figure Description

[0033] Figure 1 This is a schematic diagram of the structure of the highly absorbent hydrocolloid dressing in the embodiments of this application.

[0034] Explanation of reference numerals in the attached diagram: 1. Water-based adhesive layer; 2. Release layer; 3. Substrate layer. Detailed Implementation

[0035] The raw materials in this application include the following: Hot melt adhesive: Commercially available polyurethane hot melt adhesive, model TPU 970DU, manufactured by Covestro in Germany; Polyisobutylene: Purchased from Hubei Langbowan Biomedical Co., Ltd., a commercially available product with model number LBW-hd98; CMC: Commercially available sodium carboxymethyl cellulose, model FVH9, purchased from Henan Linbang Biotechnology Co., Ltd. Aluminum citrate: purchased from Hubei Langbowan Biomedical Co., Ltd. as a commercially available product with model number LBW-3154; Glucono-δ-lactone: Purchased from Thermo Fisher Scientific (China) Co., Ltd. as commercially available product number C27105; Sodium alginate: purchased from Merck AG, Germany, product number 180947 (commercially available product); N,N'-methylenebisacrylamide crosslinking agent: purchased from Merck GmbH, Germany, product number M7279; Ammonium persulfate: purchased from Merck AG, Germany, product number 09913, a commercially available product; Polydopamine: Purchased from Xi'an Qiyue Biotechnology Co., Ltd. as a commercially available product with product number 5651.

[0036] Preparation Example 1 The preparation method of acrylamide-grafted calcium alginate includes the following steps: Step 1: Dissolve acrylamide monomer, N,N'-methylenebisacrylamide crosslinking agent, ammonium persulfate and sodium alginate in water, stir until homogeneous to obtain a prepolymer solution. The concentration of acrylamide monomer is 10% (w / v), the concentration of N,N'-methylenebisacrylamide is 0.3% (w / v), the concentration of ammonium persulfate is 0.1% (w / v), and the concentration of sodium alginate is 0.5% (w / v) by mass-volume ratio. Step 2: Place the prepolymer liquid in an inert N2 environment and irradiate it with a UV lamp for 15 minutes to obtain a polymer gel material. The UV lamp has a power of 100W, a wavelength of 365nm, and an irradiation distance of 15 minutes. Step 3: Immerse the polymerized gel material in calcium chloride solution for 1 hour, then wash it three times with deionized water to obtain acrylamide-grafted calcium alginate.

[0037] The present application will be further described in detail below with reference to embodiments and comparative examples.

[0038] Example 1

[0039] A method for preparing a highly absorbent hydrocolloid dressing includes the following steps: S1. 60 kg of hot melt adhesive is put into a kneader and melted at 110°C and 120 r / min until homogeneous to obtain hot melt adhesive melt. S2. Add 8 kg of polyisobutylene to the hot melt adhesive melt and mix for 5 min at the same temperature and speed. After mixing evenly, add 25 kg of CMC and 2 kg of crosslinked CMC and knead for 20 min. Then add 5 kg of calcium alginate and knead for 15 min. Discharge to obtain the water-based adhesive layer. S3. Apply the water-based adhesive layer onto the substrate layer, cool to room temperature, and then cover the other side of the water-based adhesive layer with a release layer to obtain a highly absorbent hydrocolloid dressing. The thickness of the water-based adhesive layer is 0.5 mm. See [link to documentation]. Figure 1 The resulting highly absorbent hydrocolloid dressing consists of a substrate layer, a hydrocolloid layer, and a release layer from bottom to top.

[0040] The preparation method of cross-linked CMC includes the following steps: after adjusting the pH of 3wt% aluminum citrate solution to 6.5, CMC with a degree of substitution of 1 is added to the aluminum citrate solution, mixed evenly, gluconate-δ-lactone is added, stirred evenly, and allowed to stand for 6 hours to obtain cross-linked CMC. The mixing mass ratio of aluminum citrate to CMC is 1:20, and the amount of gluconate-δ-lactone added is 1% of the mass of aluminum citrate solution.

[0041] Example 2-3 Examples 2-3 are based on the preparation method of Example 1, but the components of the highly absorbent hydrocolloid dressing are adjusted as shown in Table 1.

[0042] Comparative Examples 1-3 Comparative Examples 1-3 were prepared using the same method as in Example 1, but with adjustments made to the composition of the highly absorbent hydrocolloid dressing. The specific adjustments are shown in Table 1.

[0043] Performance testing The highly absorbent hydrocolloid dressings of Examples 1-3 and Comparative Examples 1-3 were analyzed using the following specific testing methods: 1. Liquid absorption capacity The liquid absorption of the superabsorbent hydrocolloid dressing was tested according to the standard test method specified in YY / T0471.1-2004.

[0044] 2. Stretchability The stretchability of highly absorbent hydrocolloid dressings was tested according to the standard test method specified in YY / T0471.4-2004.

[0045] Based on the above detection method, the test results of Examples 1-3 and Comparative Examples 1-3 were obtained, as shown in Table 1 below.

[0046] Table 1. Components and performance test results of the highly absorbent hydrocolloid dressings of Examples 1-3 and Comparative Examples 1-3.

[0047] Referring to Table 1, comparing Examples 1-3 and Comparative Examples 1-3, it can be seen that the performance of the high-absorbency hydrocolloid dressings of Examples 1-3 is significantly better than that of the high-absorbency hydrocolloid dressings of Comparative Examples 1-3. This may be because the high-absorbency hydrocolloid dressings of Examples 1-3 use a CMC and cross-linked CMC composite system. CMC can quickly absorb wound exudate and form a gel. Cross-linked CMC has a three-dimensional network structure, which helps to enhance the stability of the hydrocolloid network. With the addition of calcium alginate, it can work with CMC to further absorb a large amount of wound exudate. Calcium alginate itself has good gelling properties and will form a moist gel layer at the wound, thereby working synergistically with CMC and cross-linked CMC to reduce the probability of liquid spreading to the surroundings, thus obtaining a highly absorbent hydrocolloid dressing.

[0048] Examples 4-7 Examples 4-7 are based on the preparation method of Example 1, but the degree of substitution of the raw material CMC in the crosslinked CMC preparation process is adjusted, as shown in Table 2.

[0049] The highly absorbent hydrocolloid dressings of Examples 4-7 were subjected to the above-mentioned performance tests, and the test results are shown in Table 2.

[0050] Table 2. CMC Substitution Degree and Performance Test Results for Examples 1 and 4-7

[0051] Referring to Table 2, a comparison of Examples 1 and 4-7 shows that the high-absorbency hydrocolloid dressing exhibits the best performance when the degree of CMC substitution is between 0.7 and 1.2, especially when the degree of CMC substitution is 1. This may be because when the CMC substitution is too low, the number of carboxyl groups on the CMC available for aluminum ion crosslinking decreases, which not only leads to poorer solubility of CMC in water but also results in a sparse three-dimensional network structure with low crosslinking density, making it prone to breakage and disintegration after liquid absorption, thus significantly reducing the absorbency of the hydrocolloid dressing for exudate. When the CMC substitution is too high, it may make the CMC too hydrophilic, resulting in extremely high solution viscosity, making it difficult to mix uniformly with aluminum citrate and glucono-δ-lactone during the preparation of crosslinked CMC. Furthermore, too many carboxyl sites can lead to excessively dense crosslinking points, which can cause violent reactions with aluminum ions during pH reduction, resulting in excessive local crosslinking and decreased absorbency of the hydrocolloid dressing.

[0052] Examples 8-11 Examples 8-11 are based on the preparation method of Example 1, but the mixing mass ratio of aluminum citrate and CMC in the preparation of crosslinked CMC is adjusted, as shown in Table 3.

[0053] The highly absorbent hydrocolloid dressings of Examples 8-11 were subjected to the above-mentioned performance tests, and the test results are shown in Table 3.

[0054] Table 3. Mass ratio of aluminum citrate to CMC and its performance test results in Examples 1 and 8-11

[0055] Referring to Table 3, comparing Examples 1 and 8-11, it can be seen that when the mass ratio of aluminum citrate to CMC is between 1:15 and 35, especially when the mass ratio is between 1:20, the resulting highly absorbent hydrocolloid dressing exhibits the best performance. This may be because when the amount of aluminum citrate added is too high, it leads to excessive cross-linking, causing the CMC molecular chains to become excessively coiled and rigid, making it difficult to swell sufficiently after absorbing water, resulting in a significant decrease in the absorbency of the hydrocolloid dressing. When the amount of aluminum citrate added is too low, the cross-linking agent is insufficient, resulting in a low cross-linking density. The resulting cross-linked CMC still has high water solubility and cannot form a strong gel network after absorbing water, thus failing to provide skeletal support.

[0056] Example 12

[0057] Example 12 is based on the preparation method of Example 1, except that calcium alginate is replaced with acrylamide-grafted calcium alginate in equal amounts, while the other conditions remain unchanged.

[0058] Performance testing The highly absorbent hydrocolloid dressings of Examples 1 and 12 were analyzed using the following specific testing methods: 1. Properties of cold flow Circular test samples (with release paper on one side) were cut using a 1-inch diameter die. Five test samples of each hydrocolloid adhesive were cut and arranged at equal intervals on the release paper. A plastic sheet was placed on top of the samples (completely covering the five test samples below), and a 3.3 kg metal block was placed on the plastic sheet. After 24 hours, the metal block and plastic sheet were removed, the diameter of the test samples was measured, and the percentage increase (%) relative to the initial diameter was calculated. The average of the percentages obtained from the five samples was used to characterize the cold flow properties of the samples.

[0059] Based on the above detection method, the test results of Example 1 and Example 12 were obtained, as shown in Table 4 below.

[0060] Table 4 Performance test results for Examples 1 and 12

[0061] Referring to Table 4, a comparison of Example 1 and Example 12 shows that the performance of the high-absorbency hydrocolloid dressing of Example 12 is significantly better than that of the high-absorbency hydrocolloid dressing of Example 1. This may be because the introduction of acrylamide increases the hydrophilic groups, which significantly improves the absorption capacity. Furthermore, the long polymer chains formed by acrylamide grafting can form a flexible network through covalent bonds and cooperate with calcium alginate to form a rigid network, resulting in a higher performance of the obtained high-absorbency hydrocolloid dressing.

[0062] In addition, aluminum ions in aluminum citrate-crosslinked CMC and calcium ions in acrylamide-grafted calcium alginate may simultaneously interact with negatively charged groups such as carboxyl groups to form a more complex "mixed ionic crosslinking" network, further enhancing the mechanical stability of the gel.

[0063] Example 13

[0064] Example 13 is based on the preparation method of Example 12, in which polydopamine and calcium alginate are added in S2, and then kneaded and discharged to obtain a water-based adhesive layer. The mass ratio of acrylamide-grafted calcium alginate to polydopamine is 1:0.1, and the other conditions remain unchanged.

[0065] Examples 14-17 Examples 14-17 are based on the preparation method of Example 13, but the mixing mass ratio of acrylamide-grafted calcium alginate and polydopamine is adjusted as shown in Table 5.

[0066] Performance testing The highly absorbent hydrocolloid dressings of Examples 12-17 were analyzed using the following specific testing methods: 1. Antibacterial properties Cut the hydrocolloid dressing sample into 1.0*1.0cm pieces and place them in an Erlenmeyer flask. Then add the same volume of phosphate buffer, followed by Staphylococcus aureus and Escherichia coli suspensions, adjusting the concentration of the bacterial suspensions in PBS to 1×10⁻⁶. 4 ~9×10 4 CFU / mL, fix the Erlenmeyer flask on a shaking table and shake at 300 r / min for 1 h. Take the sample solution before and after shaking, dilute it appropriately with PBS, and inoculate it into Petri dishes by agar pouring method. Count the colonies. The inhibition rate is the ratio of the difference between the average number of colonies before and after shaking to the average number of colonies before shaking, expressed as a percentage.

[0067] Based on the above detection method, the test results of Examples 12-17 were obtained, as shown in Table 5 below.

[0068] Table 5. Mixed mass ratio and performance test results of acrylamide-grafted calcium alginate and polydopamine in Examples 12-17.

[0069] Referring to Table 5, a comparison of Examples 12 and 13 shows that the performance of the hyperabsorbent hydrocolloid dressing in Example 13 is significantly better than that in Example 12. This is likely because the addition of polydopamine not only helps improve the antibacterial properties of the hydrocolloid dressing, but also synergizes with the acrylamide segments in acrylamide-grafted calcium alginate, and chelates the calcium ions released by calcium alginate through the catechol groups, significantly improving the flexibility of the hyperabsorbent hydrocolloid dressing. Furthermore, polydopamine can also form catechol-Al with aluminum ions in the system. 3+ Coordination bonds significantly enhance the mechanical strength of hydrocolloid dressings.

[0070] Comparative examples 13-17 show that when the mass ratio of acrylamide-grafted calcium alginate to polydopamine is in the range of 1:0.05-0.2, especially when the mass ratio of acrylamide-grafted calcium alginate to polydopamine is 1:0.1, the resulting highly absorbent hydrocolloid dressing exhibits the best performance. This may be because when the proportion of acrylamide-grafted calcium alginate is too high, the amount of polydopamine added is insufficient, resulting in a decrease in the adhesion between the hydrocolloid dressing and the skin around the wound. Furthermore, when there is too little polydopamine, the π-π stacking and hydrogen bonding between polydopamine and polyacrylamide segments decrease, thereby weakening the synergistic enhancement effect between the cross-linked networks in the system.

[0071] When the proportion of acrylamide-grafted calcium alginate is too low, excessive polydopamine may over-crosslink or occupy the gel network space, inhibiting the rapid swelling and high liquid absorption capacity of acrylamide-grafted calcium alginate, resulting in a significant decrease in the liquid absorption of the hydrocolloid dressing. Furthermore, insufficient addition of acrylamide-grafted calcium alginate will lead to a lack of ideal mechanical support in the system, resulting in a loose overall structure and decreased cohesion.

[0072] Examples 18-21 Examples 18-21 are based on the preparation method of Example 1, but the melting temperature of the hot melt adhesive is adjusted as shown in Table 6.

[0073] The highly absorbent hydrocolloid dressings of Examples 18-21 were subjected to the above-mentioned performance tests, and the test results are shown in Table 6.

[0074] Table 6. Melting temperature and performance test results for Examples 1 and 18-21

[0075] Referring to Table 6, a comparison of Examples 1 and 18-21 shows that the high-absorbency hydrocolloid dressing exhibits the best performance when the melting temperature is within the range of 100-120°C, especially when the melting temperature is 110°C. This may be because when the melting temperature is too high, the excessive temperature may cause CMC to dehydrate and char, reducing its hydration capacity and swelling properties, while also destroying the gel structure of sodium alginate, resulting in a significant decrease in the liquid absorption capacity of the hydrocolloid dressing. When the melting temperature is too low, the hot melt adhesive cannot be completely melted into a uniform melt, resulting in the subsequent addition of raw materials not being evenly dispersed, thus degrading the performance of the resulting hydrocolloid dressing.

[0076] This specific embodiment is merely an explanation of this application and is not intended to limit it. After reading this specification, those skilled in the art can make modifications to this embodiment without contributing any inventive step, but such modifications are protected by patent law as long as they fall within the scope of the claims of this application.

Claims

1. A highly absorbent hydrocolloid dressing, characterized in that, It includes a substrate layer, a release layer, and a water-based adhesive layer disposed between the substrate layer and the release layer; the water-based adhesive layer comprises the following raw materials in parts by weight: 55-65 parts hot melt adhesive, 5-10 parts polyisobutylene, 20-30 parts CMC, 1-3 parts crosslinked CMC, and 3-8 parts calcium alginate.

2. The highly absorbent hydrocolloid dressing according to claim 1, characterized in that, The preparation method of the cross-linked CMC includes the following steps: adjusting the pH of the aluminum citrate solution to 6-7, adding CMC to the aluminum citrate solution, mixing evenly, adding gluconate-δ-lactone, stirring evenly, and allowing it to stand to obtain cross-linked CMC.

3. The highly absorbent hydrocolloid dressing according to claim 2, characterized in that, The degree of substitution of the CMC is 0.7-1.

2.

4. The highly absorbent hydrocolloid dressing according to claim 2, characterized in that, The mass ratio of aluminum citrate to CMC is 1:15-35.

5. The highly absorbent hydrocolloid dressing according to claim 1, characterized in that, The calcium alginate is acrylamide-grafted calcium alginate.

6. The highly absorbent hydrocolloid dressing according to claim 5, characterized in that, It also contains polydopamine.

7. The highly absorbent hydrocolloid dressing according to claim 6, characterized in that, The mass ratio of acrylamide-grafted calcium alginate to polydopamine is 1:0.05-0.

2.

8. A method for preparing a highly absorbent hydrocolloid dressing according to any one of claims 1-7, characterized in that, Includes the following steps: S1. Melt the hot melt adhesive according to the formula to obtain hot melt adhesive melt; S2. Add the formulated amount of polyisobutylene to the hot melt adhesive melt, mix evenly, then add the formulated amount of CMC and cross-linked CMC, rotate and knead, then add calcium alginate, knead and discharge to obtain the water adhesive layer. S3. Apply the water-based adhesive layer onto the substrate layer, and after cooling, cover the other side of the water-based adhesive layer with a release layer to obtain a highly absorbent hydrocolloid dressing.

9. The method for preparing a highly absorbent hydrocolloid dressing according to claim 8, characterized in that, In S2, polydopamine and calcium alginate are added to the formula and mixed, then kneaded and discharged to obtain a water-based adhesive layer.

10. A method for preparing a highly absorbent hydrocolloid dressing according to claim 9, characterized in that, The hot melt adhesive has a melting temperature of 100-120℃.

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