Anti-swelling and moisture-permeable polyurethane film, and preparation method and application thereof

Abstract

The application relates to an anti-swelling and moisture-permeable polyurethane film and a preparation method and application thereof. The preparation raw material of the anti-swelling and moisture-permeable polyurethane film comprises a prepolymer containing terminal isocyanate groups, a chain extender and a hydrophilic polyether polyol; the prepolymer containing terminal isocyanate groups is prepared by reacting a polyether polyol and diisocyanate; the hydrophilic polyether polyol is polyethylene glycol; and the anti-swelling and moisture-permeable polyurethane film is a film subjected to irradiation crosslinking treatment. The anti-swelling and moisture-permeable polyurethane film provided by the application has excellent water vapor permeability and low swelling rate on the basis of good mechanical properties (high hydrostatic pressure), and can well and completely meet the requirements of a wound dressing on moisture permeability and adhesion.

Description

Technical Field

[0001] This application relates to the field of polymer film technology, and in particular to an anti-swelling and moisture-permeable polyurethane film, its preparation method, and its application. Background Technology

[0002] Thermoplastic polyurethane (TPU) films are widely used in medical dressings due to their excellent physicochemical properties. However, in pursuing high moisture permeability, traditional TPU films often suffer from reduced anti-swelling properties, making them prone to swelling and deformation upon contact with wound exudate, thus compromising the film's smoothness and functionality. This is particularly crucial in wound dressing applications, where the film needs both good moisture permeability to promote wound healing and excellent anti-swelling properties to maintain stable protective effects.

[0003] CN104262946A discloses an antibacterial composite TPU film and its preparation method. The antibacterial composite TPU film comprises the following components by weight: 60-80 parts TPU particles, 20-30 parts antibacterial agent, 0.1-0.3 parts antioxidant, and 1-3 parts additives. The preparation method includes: (1) mixing the components according to the above weight proportions; (2) plasticizing the mixture using an extruder to form a semi-finished product; (3) filtering and re-plasticizing the semi-finished product using a filter; and (4) processing the film using a four-roll forming machine. Although the obtained TPU film has a certain antibacterial effect, it still has shortcomings in balancing anti-swelling and moisture permeability.

[0004] Therefore, designing and developing a TPU film that combines excellent anti-swelling properties with good moisture permeability has become a technical challenge that urgently needs to be solved in the field of medical dressing materials. Summary of the Invention

[0005] To address the aforementioned technical problems, this application provides an anti-swelling and breathable polyurethane film, its preparation method, and its application. The anti-swelling and breathable polyurethane film, in addition to possessing good mechanical properties (high hydrostatic pressure), also exhibits excellent water vapor permeability and low swelling rate, thus effectively and completely meeting the requirements of wound dressings for breathability and adhesion.

[0006] To achieve this objective, the following technical solution is adopted in this application: In a first aspect, this application provides an anti-swelling and moisture-permeable polyurethane film, wherein the raw materials for preparing the anti-swelling and moisture-permeable polyurethane film include a prepolymer containing terminal isocyanate groups, a chain extender, and a hydrophilic polyether polyol. The prepolymer containing terminal isocyanate groups is prepared by reacting polyether polyol and diisocyanate. The hydrophilic polyether polyol is polyethylene glycol (PEG). The anti-swelling and moisture-permeable polyurethane film is a film obtained after radiation crosslinking treatment.

[0007] This application achieves molecular design for an anti-swelling and breathable polyurethane film by introducing hydrophilic polyether polyols into the raw materials and subjecting them to irradiation crosslinking treatment. This integrates structure and function, avoiding the risk of interlayer delamination that may exist in multilayer composite structures, resulting in stable and durable performance. The anti-swelling and breathable polyurethane film provided by this application, in addition to having good mechanical properties (high hydrostatic pressure), also features excellent water vapor permeability and low swelling rate, effectively meeting the needs of wound dressings for breathability and adhesion.

[0008] In this application, the hydrophilic polyether polyol is PEG, whose repeating unit is -CH2-CH2-O-. The ether oxygen atom interacts with water molecules through hydrogen bonds, and can adsorb / dissolve water vapor. The hard segments form physical cross-linking points, providing good mechanical strength. The PEG soft segments act as a continuous phase or through-channel, allowing adsorbed water molecules to "jump" and transfer along the PEG segments, which is beneficial for swelling and diffusion. The introduction of the hydrophilic polyether polyol can form continuous hydrophilic microdomains inside the film, providing a rapid diffusion path for water vapor, significantly improving the water vapor transmission rate (MVTR) of the film, thereby endowing the film with excellent moisture permeability.

[0009] By introducing the specific hydrophilic polyether polyol and subjecting the film to controlled irradiation crosslinking treatment, a stable three-dimensional network structure can be constructed between TPU molecular chains. This crosslinking network effectively restricts the movement of polymer chain segments in a humid environment, inhibiting excessive hydration and expansion of hydrophilic segments. This effectively controls the swelling rate of the film in simulated exudate, significantly suppressing excessive swelling and deformation caused by water absorption. This overcomes the performance contradiction between moisture permeability and swelling resistance, achieving a high level of unity between the two. The resulting anti-swelling and moisture-permeable polyurethane film maintains high moisture permeability while also possessing excellent anti-swelling performance and dimensional stability. The synergistic effect of introducing hydrophilic segments and constructing the irradiation crosslinking network effectively solves the long-standing technical problem of "swelling when permeable and stuffiness when resistant to swelling" in medical films. Furthermore, while improving swelling resistance, irradiation crosslinking also serves as an effective physical reinforcement point, compensating for the potential decrease in mechanical properties caused by the introduction of the hydrophilic polyether polyol. This results in a polyurethane film that is highly permeable and has low swelling, while also having high hydrostatic pressure, ensuring the mechanical integrity and reliability of the dressing during application.

[0010] In some embodiments, the molar ratio of the polyether polyol to the diisocyanate is (0.03-0.15):1, wherein (0.03-0.15) can be, for example, 0.03, 0.04, 0.05, 0.06, 0.07, 0.08, 0.09, 0.1, 0.12, or 0.15, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list all the specific values ​​included in the range.

[0011] It should be noted that the molar amount of the polyether polyol in this application is calculated by comparing its actual mass used with the number-average molecular weight (or average value if it is a range).

[0012] In some embodiments, the polyether polyol includes polytetrahydrofuran diol (PTMG) and / or polyethylene glycol (PEG).

[0013] In some embodiments, the polyether polyol is polytetrahydrofuran diol (PTMG).

[0014] In some embodiments, the number average molecular weight (Mn) of the polyether polyol is 1000-2500, for example, it can be 1000, 1250, 1400, 1500, 1600, 1800, 2000, 2200 or 2500, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0015] In some embodiments, the diisocyanate includes any one or a combination of at least two of 4,4'-diphenylmethane diisocyanate (MDI), isophorone diisocyanate (IPDI), or hexamethylene diisocyanate (HDI).

[0016] In some embodiments, the reaction temperature is 70-90°C, for example, it can be 70°C, 72°C, 74°C, 76°C, 78°C, 80°C, 82°C, 84°C, 86°C, 88°C or 90°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0017] In some embodiments, the reaction time is 1-3 h, for example, it can be 1 h, 1.2 h, 1.4 h, 1.6 h, 1.8 h, 2 h, 2.2 h, 2.4 h, 2.6 h, 2.8 h or 3 h, as well as specific point values ​​between the above point values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific point values ​​included in the range.

[0018] In some embodiments, the chain extender includes monoallyl ethers of diols and small molecule diols.

[0019] In some embodiments, the monoallyl ether of the diol comprises 3-allyloxy-1,2-propanediol.

[0020] In some embodiments, the content of the monoallyl ether of the diol is 5-10% of the total mass of the chain extender, for example, it can be 5%, 5.5%, 6%, 6.5%, 7%, 7.5%, 8%, 8.5%, 9%, 9.5% or 10%, and specific values ​​between the above points. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0021] In some embodiments, the chain extender includes any one or a combination of at least two of ethylene glycol (EG), 1,4-butanediol (BDO), diethylene glycol (DEG), or 1,6-hexanediol (HDO).

[0022] In some embodiments, the mass ratio of the chain extender to the hydrophilic polyether polyol is 1:(4-6), wherein (4-6) can be, for example, 4, 4.2, 4.4, 4.6, 4.8, 5, 5.2, 5.4, 5.6, 5.8 or 6, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0023] In some embodiments, the number average molecular weight of the hydrophilic polyether polyol is 400-6000, for example, it can be 400, 600, 800, 1000, 2000, 3000, 4000, 5000 or 6000, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0024] In some embodiments, the number average molecular weight of the hydrophilic polyether polyol is 1000-3000, for example, it can be 1000, 1200, 1500, 1800, 2000, 2200, 2500, 2800 or 3000, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0025] In this application, by optimizing the number-average molecular weight of the hydrophilic polyether polyol, the polyurethane film can achieve better mechanical properties while forming continuous hydrophilic channels. However, when the molecular weight of the hydrophilic polyether polyol is low or high, the water vapor permeability and hydrostatic pressure of the resulting polyurethane film are significantly reduced.

[0026] When the molecular weight of hydrophilic polyether polyols is low, the soft segments are too short, making it impossible to establish microphase separation. The proportion of hard segments (diisocyanate + chain extender) is passively increased, and the short PEG chains are embedded within the hard segment sea. The soft segment region is discontinuous, and the hydrophilic channels are broken into discontinuous fragments, hindering the water vapor dissolution-diffusion pathway. Furthermore, when the molecular weight of hydrophilic polyether polyols is low, they tend to crystallize at room temperature. Although the ether bonds are hydrophilic, they are frozen in the crystalline segments, allowing water molecules to enter but preventing them from moving, resulting in a significant decrease in the diffusion coefficient. When the molecular weight of hydrophilic polyether polyols is high, especially PEG with a molecular weight (Mn > 3000), crystallization is significant at room temperature. The crystalline regions are characterized by "hydrophilicity but frozen chain segments + isolated regions"—water molecules can dissolve into the amorphous regions, but the crystalline regions cut off continuous hydrophilic channels, slowing down overall diffusion. A higher proportion of soft segments leads to dilution of hard segments and insufficient physical cross-linking points, resulting in film collapse and a significant decrease in hydrostatic pressure resistance, making it unsuitable for textile lamination or medical membranes. This study found that when the PEG molecular weight varies from 400 to 6000, the film's moisture permeability exhibits a parabolic shape. When the number-average molecular weight of PEG is between 1000 and 3000, the moisture permeability is higher, and the film's hydrostatic pressure resistance is more suitable.

[0027] In some embodiments, the molar ratio of the hydrophilic polyether polyol to the diisocyanate is (0.1-0.4):1, wherein (0.1-0.4) can be, for example, 0.1, 0.15, 0.2, 0.25, 0.3, 0.35 or 0.4, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0028] In this application, by optimizing the content of hydrophilic polyether polyol, the resulting polyurethane film can possess both good moisture permeability and superior hydrostatic pressure. When the molar ratio of hydrophilic polyether polyol to diisocyanate is low, the soft segment regions cannot be better connected, and the water vapor permeation path is obstructed, resulting in decreased moisture permeability. When the molar ratio of hydrophilic polyether polyol to diisocyanate is high, the hard segment content is low, and physical cross-linking points cannot be formed effectively, leading to deteriorated mechanical properties, poor film properties, and a significant decrease in hydrostatic pressure.

[0029] It should be noted that the molar amount of the hydrophilic polyether polyol in this application is calculated by comparing its actual mass used with the number-average molecular weight (or average value if it is a range).

[0030] In some embodiments, the absorbed dose of the irradiation crosslinking treatment is 5-50 kGy, for example, it can be 5 kGy, 10 kGy, 15 kGy, 20 kGy, 25 kGy, 30 kGy, 35 kGy, 40 kGy, 45 kGy or 50 kGy, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0031] In some embodiments, the absorbed dose of the irradiation crosslinking treatment is 15-40 kGy, for example, it can be 15 kGy, 20 kGy, 25 kGy, 30 kGy, 35 kGy or 40 kGy, as well as specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0032] In this application, the network formed by irradiation crosslinking is a bulk crosslinking, not a surface coating. Therefore, the anti-swelling properties of the resulting film will not decrease due to surface wear or long-term use, resulting in more reliable performance and a longer service life. The absorbed dose of irradiation crosslinking is a key "valve" for adjusting the performance balance. By optimizing the absorbed dose of the irradiation crosslinking treatment, the crosslinking density of the film can be effectively adjusted, achieving better anti-swelling effects without compromising the film's flexibility and moisture permeability. When the absorbed dose is low, an effective crosslinking network cannot be formed, resulting in insufficient anti-swelling effect; when the absorbed dose is high, it easily leads to excessive polymer crosslinking, resulting in an overly dense crosslinking network, which reduces the film's moisture permeability and decreases its flexibility during processing.

[0033] In some embodiments, the irradiation crosslinking treatment method includes electron beam irradiation and / or gamma ray irradiation.

[0034] Secondly, this application provides a method for preparing an anti-swelling and moisture-permeable polyurethane film as described in the first aspect, the method comprising the following steps: A prepolymer containing terminal isocyanate groups, a chain extender, and a hydrophilic polyether polyol are melt-reacted, granulated, and cast to obtain an initial moisture-permeable film; the initial moisture-permeable film is then subjected to irradiation crosslinking treatment to obtain the anti-swelling moisture-permeable polyurethane film.

[0035] In some embodiments, the melt reaction is carried out in a twin-screw extruder.

[0036] In some embodiments, the temperature of the melting reaction is 150-210°C, for example, it can be 150°C, 155°C, 160°C, 165°C, 170°C, 175°C, 180°C, 185°C, 190°C, 195°C, 200°C, 205°C or 210°C, as well as specific values ​​between the above points. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0037] In some embodiments, the granulation is carried out underwater, and there is no particular limitation on the temperature. Conventional temperature settings in the art are applicable, including but not limited to 20-40°C.

[0038] In some embodiments, the granulation process further includes a drying step.

[0039] In some embodiments, after drying, the water content of the polyurethane particles obtained by granulation is ≤500 ppm, for example, it can be 100 ppm, 150 ppm, 200 ppm, 250 ppm, 300 ppm, 350 ppm, 400 ppm, 450 ppm or 500 ppm, and specific values ​​between the above values. Due to space limitations and for the sake of brevity, this application will not exhaustively list the specific values ​​included in the range.

[0040] In some embodiments, the casting process further includes a cooling step.

[0041] It should be noted that there is no special limitation on the cooling temperature in this application, and conventional cooling temperatures in the art are applicable, including but not limited to room temperature (20-30°C).

[0042] In some embodiments, the irradiation crosslinking treatment is performed under a protective gas atmosphere.

[0043] In some embodiments, the protective gas includes any one or a combination of at least two of nitrogen, argon, or helium.

[0044] In some embodiments, the method for preparing the anti-swelling and moisture-permeable polyurethane film specifically includes the following steps: After mixing polyether polyol and diisocyanate in a molar ratio of (0.03-0.15):1, the mixture is reacted at 70-90℃ for 1-3 h to obtain a prepolymer containing terminal isocyanate groups. The prepolymer containing terminal isocyanate groups, chain extender, and hydrophilic polyether polyol are melt-reacted in a twin-screw extruder at 150-210°C and granulated underwater to obtain polyurethane particles. The polyurethane particles are dried to a water content of ≤500 ppm, then cast and cooled to obtain an initial moisture-permeable film. The initial moisture-permeable film is then subjected to irradiation crosslinking treatment with an absorbed dose of 5-50 kGy under a protective gas atmosphere to obtain the anti-swelling moisture-permeable polyurethane film.

[0045] Thirdly, this application provides the application of an anti-swelling and breathable polyurethane film as described in the first aspect in wound dressings.

[0046] In the preparation of the anti-swelling and breathable polyurethane film provided in this application, the selected hydrophilic polyether polyol PEG is an FDA-approved biocompatible material. Irradiation crosslinking is a physical, green process, and the entire preparation process does not introduce chemical crosslinking agents, leaving no residue of toxic chemical crosslinking agents. The resulting anti-swelling and breathable polyurethane film maintains excellent biocompatibility and user comfort. It is not only soft and elastic, conforming well to the skin, but also, due to its high breathability, can promptly expel moisture from the wound, preventing infiltration and creating an ideal environment for wound healing. Simultaneously, it keeps the skin around the wound dry and comfortable, greatly improving the patient's user experience.

[0047] Compared with the prior art, this application has at least the following beneficial effects: (1) The anti-swelling and breathable polyurethane film provided in this application breaks through the performance contradiction between breathability and anti-swelling, and achieves a high level of unity between the two, effectively solving the long-standing technical problem of "swelling when breathable and stuffiness when anti-swelling" in medical films; it has an integrated structure, stable and durable performance, and a longer service life; while achieving high breathability and low swelling, it also has high hydrostatic pressure, ensuring the mechanical integrity and reliability of the dressing during application; at the same time, it also maintains excellent biocompatibility and user comfort, providing an ideal environment for wound healing while greatly improving the patient's user experience. Furthermore, the core process in the preparation method of this application (hydrophilic polyether polyol copolymerization + post-treatment irradiation) is mature and controllable. By optimizing the content of specific hydrophilic polyether polyol and the parameters of radiation treatment, the obtained anti-swelling and breathable polyurethane film can be customized to adjust the balance point of breathability and anti-swelling for different wound types (high exudation or low exudation), which has strong production adaptability and is easy to achieve large-scale production.

[0048] (2) The anti-swelling and breathable polyurethane film provided in this application has excellent anti-swelling and breathable properties in addition to good mechanical properties, with a water vapor transmission rate (MVTR) ≥1300 g / (m 2 • 24h), swelling rate ≤10%, hydrostatic pressure ≥7200 mmH2O. Detailed Implementation

[0049] To facilitate understanding of this application, the following embodiments are provided. Those skilled in the art should understand that these embodiments are merely illustrative and should not be construed as limiting the scope of this application.

[0050] Unless otherwise specified, the materials and equipment involved in the following detailed embodiments are all conventional materials and equipment in the art and will not affect the technical effect of this application.

[0051] Unless otherwise specified, all reagents and raw materials used in the following examples and comparative examples are commercially available products. Some raw material information is as follows: Polytetrahydrofuran diol: PTMG-1000, purchased from Hyosung PTMG 1000G; Polyethylene glycol 1: PEG-1500, purchased from Changhua Chemical CHPEG-1500; Polyethylene glycol 2: Number average molecular weight of 1000, purchased from Changhua Chemical CHPEG-1000; Polyethylene glycol 3: number average molecular weight 3000, purchased from Changhua Chemical CHPEG-3000; Polyethylene glycol 4: Number average molecular weight 4000, purchased from Changhua Chemical CHPEG-4000; Polyethylene glycol 5: Number average molecular weight 400, purchased from Changhua Chemical CHPEG-400; Polypropylene glycol (PPG): number average molecular weight 2000, purchased from Changhua Chemical CHE-822P.

[0052] Example 1 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method, the preparation method comprising the following steps: Polytetrahydrofuran diol (PTMG-1000, 100 parts by weight) and 4,4'-diphenylmethane diisocyanate (MDI, 362.87 parts by weight) (molar ratio of 0.07:1) were mixed and reacted at 80°C for 2 h to obtain a prepolymer containing terminal isocyanate groups. The prepolymer containing terminal isocyanate groups, 3-allyloxy-1,2-propanediol (8 parts by weight), 1,4-butanediol (BDO, 88 parts by weight), and polyethylene glycol 1 (PEG-1500, 427.2 parts by weight) were injected into the feed port of a twin-screw extruder for a melt reaction. The temperature range of each section of the screw was 150-210°C. After underwater granulation and curing in a silo, polyurethane particles were obtained. The polyurethane particles were dried to a moisture content of 300 ppm and then extruded through a casting machine screw to a die head for casting. After cooling by guide rollers, the particles were wound up to obtain an initial moisture-permeable film. The initial moisture-permeable film was then subjected to irradiation crosslinking treatment with an absorbed dose of 25 kGy under a protective gas atmosphere to obtain the anti-swelling moisture-permeable polyurethane film.

[0053] Example 2 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method, the preparation method comprising the following steps: Polyethylene glycol 1 (PEG-1500, 337 parts by weight) and isophorone diisocyanate (IPDI, 333.42 parts by weight) (molar ratio of 0.15:1) were mixed and reacted at 70°C for 3 h to obtain a prepolymer containing terminal isocyanate groups. A prepolymer containing terminal isocyanate groups, 3-allyloxy-1,2-propanediol (9 parts by weight), 1,6-hexanediol (HDO, 86 parts by weight), and polyethylene glycol 2 (PEG, 570 parts by weight) are injected into the feed port of a twin-screw extruder for melt reaction. The temperature range of each section of the screw is 150-210°C. After underwater granulation and curing in a silo, polyurethane particles are obtained. The polyurethane particles are dried to a moisture content of 200 ppm and then extruded through a casting machine screw to a die head for casting. After cooling by guide rollers, the film is wound up to obtain an initial moisture-permeable film. The initial moisture-permeable film is then subjected to irradiation crosslinking treatment with an absorbed dose of 25 kGy under a protective gas atmosphere to obtain the swelling-resistant moisture-permeable polyurethane film.

[0054] Example 3 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method, the preparation method comprising the following steps: Polytetrahydrofuran diol (PTMG-1000, 45 parts by weight) and hexamethylene diisocyanate (HDI, 252.3 parts by weight) (molar ratio of 0.03:1) were mixed and reacted at 90°C for 1 h to obtain a prepolymer containing terminal isocyanate groups. A prepolymer containing terminal isocyanate groups, 3-allyloxy-1,2-propanediol (5 parts by weight), ethylene glycol (EG, 85 parts by weight), and polyethylene glycol 3 (PEG, 450 parts by weight) are injected into the feed port of a twin-screw extruder for melt reaction. The temperature range of each section of the screw is 150-210°C. After underwater granulation and curing in a silo, polyurethane particles are obtained. The polyurethane particles are dried to a moisture content of 400 ppm and then extruded through a casting machine screw to a die head for casting. After cooling by guide rollers, the film is wound up to obtain an initial moisture-permeable film. The initial moisture-permeable film is then subjected to irradiation crosslinking treatment with an absorbed dose of 25 kGy under a protective gas atmosphere to obtain the swelling-resistant moisture-permeable polyurethane film.

[0055] Example 4 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that polyethylene glycol 1 is replaced with an equal mass of polyethylene glycol 4. All other raw materials, contents, and preparation methods are the same as in Example 1.

[0056] Example 5 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that polyethylene glycol 1 is replaced with an equal mass of polyethylene glycol 5. All other raw materials, contents, and preparation methods are the same as in Example 1.

[0057] Example 6 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that the weight of polyethylene glycol 1 is adjusted from 427.2 parts to 218 parts (the molar ratio of polyethylene glycol 1 to MDI is 0.1:1). All other raw materials, contents and preparation methods are the same as in Example 1.

[0058] Example 7 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that the weight of polyethylene glycol 1 is adjusted from 427.2 parts to 860 parts (the molar ratio of polyethylene glycol 1 to MDI is 0.4:1). All other raw materials, contents and preparation methods are the same as in Example 1.

[0059] Example 8 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that the weight of polyethylene glycol 1 is adjusted from 427.2 parts to 108 parts (the molar ratio of polyethylene glycol 1 to MDI is 0.05:1). All other raw materials, contents and preparation methods are the same as in Example 1.

[0060] Example 9 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that the weight of polyethylene glycol 1 is adjusted from 427.2 parts to 970 parts (the molar ratio of polyethylene glycol 1 to MDI is 0.45:1). All other raw materials, contents and preparation methods are the same as in Example 1.

[0061] Example 10 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Embodiment 1 is that the absorbed dose of the irradiation crosslinking treatment is adjusted from 25 kGy to 15 kGy. All other raw materials, contents, and preparation methods are the same as in Embodiment 1.

[0062] Example 11 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Example 1 is that the absorbed dose of the irradiation crosslinking treatment is adjusted from 25 kGy to 40 kGy. All other raw materials, contents and preparation methods are the same as in Example 1.

[0063] Example 12 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Embodiment 1 is that the absorbed dose of the irradiation crosslinking treatment is adjusted from 25 kGy to 10 kGy. All other raw materials, contents, and preparation methods are the same as in Embodiment 1.

[0064] Example 13 This embodiment provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this embodiment and Embodiment 1 is that the absorbed dose of the irradiation crosslinking treatment is adjusted from 25 kGy to 50 kGy. All other raw materials, contents, and preparation methods are the same as in Embodiment 1.

[0065] Comparative Example 1 This comparative example provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this example and Example 1 is that polyethylene glycol 1 is replaced with an equimolar amount of polytetrahydrofuran glycol (PTMG-1000). All other raw materials, contents, and preparation methods are the same as in Example 1.

[0066] Comparative Example 2 This comparative example provides an anti-swelling and moisture-permeable polyurethane film and its preparation method. The only difference between this example and Example 1 is that polyethylene glycol 1 is replaced with an equimolar amount of polypropylene glycol (PPG). All other raw materials, contents, and preparation methods are the same as in Example 1.

[0067] Comparative Example 3 This comparative example provides a polyurethane film and its preparation method. The only difference between this example and Example 1 is that no radiation crosslinking treatment is performed, and the initial film is a polyurethane film. The other raw materials, contents, and preparation methods are the same as in Example 1.

[0068] Comparative Example 4 This comparative example provides a polyurethane film and its preparation method. The only difference between this example and Example 1 is that polyethylene glycol 1 is not added, and the amount of 1,4-butanediol added is adjusted from 96 parts by weight to 121.66 parts by weight. All other raw materials, contents and preparation methods are the same as in Example 1.

[0069] Comparative Example 5 This comparative example provides a polyurethane film and a method for preparing the same, the preparation method comprising the following steps: After mixing polyethylene glycol 1 (PEG-1500, 1192.5 parts by weight) and isophorone diisocyanate (IPDI, 333.42 parts by weight), the mixture was reacted at 80°C for 2 h to obtain a prepolymer containing terminal isocyanate groups. The prepolymer containing terminal isocyanate groups was injected into the feed port of a twin-screw extruder with 3-allyloxy-1,2-propanediol (9 parts by weight) and 1,6-hexanediol (HDO, 86 parts by weight) for a melt reaction. The temperature range of each section of the screw was 150-210°C. After underwater granulation and curing in a silo, polyurethane particles were obtained. The polyurethane particles were dried to a moisture content of 200 ppm and then extruded through a casting machine screw to a die head for casting. After cooling by guide rollers, the particles were wound up to obtain an initial moisture-permeable film. The initial moisture-permeable film was then subjected to irradiation crosslinking treatment with an absorbed dose of 25 kGy under a protective gas atmosphere to obtain the swelling-resistant moisture-permeable polyurethane film.

[0070] Comparative Example 6 This comparative example provides a swelling-resistant and moisture-permeable polyurethane film and its preparation method, the preparation method comprising the following steps: Polytetrahydrofuran glycol (PTMG-1000, 100 parts by weight), polyethylene glycol 1 (PEG-1500, 427.2 parts by weight), 3-allyloxy-1,2-propanediol (8 parts by weight), 1,4-butanediol (BDO, 88 parts by weight), and 4,4'-diphenylmethane diisocyanate (MDI, 362.87 parts by weight) were mixed and injected into the feed port of a twin-screw extruder for a melt reaction. The temperature range of each section of the screw was 150-210°C. After underwater granulation and curing in a hopper, polyurethane particles were obtained. The polyurethane particles were dried to a moisture content of 300 ppm and then extruded through a casting machine screw to a die head for casting. After cooling by guide rollers, the film was wound up to obtain an initial moisture-permeable film. The initial moisture-permeable film was then subjected to irradiation crosslinking treatment with an absorbed dose of 25 kGy under a protective gas atmosphere to obtain the swelling-resistant moisture-permeable polyurethane film.

[0071] The polyurethane films provided in Examples 1-13 and Comparative Examples 1-6 were subjected to performance tests, and the test methods / standards are as follows: (1) Water vapor transmission rate (MVTR): Tested according to ASTM E96; (2) Swelling rate: The initial mass of the polyurethane film is recorded as M0. After immersing it in physiological saline at 37℃ for 24 h, its mass is measured again and recorded as M1. Then the swelling rate = (M1-M0) / M0×100%; (3) Hydrostatic pressure: Tested according to AATCC TM127-2017.

[0072] The test results are shown in Table 1.

[0073] Table 1 According to the test results in Table 1: (1) As can be seen from Examples 1-13, this application achieves the molecular design of an anti-swelling and moisture-permeable polyurethane film by introducing hydrophilic polyether polyol into the raw materials for preparing the anti-swelling and moisture-permeable polyurethane film and subjecting it to irradiation crosslinking treatment. This integrates structure and function, resulting in a polyurethane film that not only has good mechanical properties but also excellent anti-swelling and moisture-permeable properties, with a water vapor transmission rate ≥1300 g / (m 2 • 24h), swelling rate ≤10%, hydrostatic pressure ≥7200 mmH2O.

[0074] (2) By comparing Examples 1-3 with Examples 4 and 5, it can be seen that by using the preferred molecular weight of the hydrophilic polyether polyol to be 1000-3000, the anti-swelling and moisture-permeable properties and mechanical properties of the obtained polyurethane film can be further improved. When the molecular weight is too high (Example 4) or too low (Example 5), the water vapor permeability and hydrostatic pressure of the obtained polyurethane film are significantly reduced and the swelling rate is increased, that is, the anti-swelling and moisture-permeable properties and mechanical properties are all worse.

[0075] (3) A comparison of Examples 1, 6, and 7 with Examples 8 and 9 shows that by adjusting the molar ratio of hydrophilic polyether polyol to diisocyanate to (0.1-0.4):1, this application can achieve superior overall performance of the obtained anti-swelling and moisture-permeable polyurethane film. When the molar ratio is lower than this range (Example 8), the water vapor transmission rate of the obtained anti-swelling and moisture-permeable polyurethane film is significantly reduced, i.e., the moisture permeability deteriorates; when the molar ratio is higher than this range (Example 9), the swelling rate of the obtained anti-swelling and moisture-permeable polyurethane film increases, and the hydrostatic pressure is significantly reduced, i.e., both the anti-swelling performance and mechanical properties deteriorate.

[0076] (4) By comparing Examples 1, 10, and 11 with Examples 12 and 13, it can be seen that by controlling the absorbed dose of the irradiation crosslinking treatment to 15-40 kGy, the resulting anti-swelling and moisture-permeable polyurethane film can have better overall performance. When the absorbed dose is lower than this range (Example 12), the water vapor transmission rate and hydrostatic pressure of the resulting anti-swelling and moisture-permeable polyurethane film are significantly reduced, and the swelling rate is significantly increased. When the absorbed dose is higher than this range (Example 13), although the anti-swelling performance of the resulting anti-swelling and moisture-permeable polyurethane film is enhanced, its water vapor transmission rate and hydrostatic pressure are significantly reduced, that is, the moisture permeability and mechanical properties are poor.

[0077] (5) A comparison of Examples 1-13 and Comparative Examples 1-4 shows that when polyethylene glycol is selected as the hydrophilic polyether polyol in this application, it can work well with the irradiation crosslinking treatment method, and can better resolve the contradiction between moisture permeability and anti-swelling properties, thereby giving the obtained polyurethane film superior anti-swelling and moisture permeability. When polyethylene glycol is not selected as the hydrophilic polyether polyol (Comparative Examples 1 and 2), the water vapor transmission rate of the obtained polyurethane film is less than 500 g / (m²). 2 • 24h), meaning the moisture permeability is significantly poor. Furthermore, when no hydrophilic polyether polyol is added and only irradiation crosslinking treatment is performed (Comparative Example 4), the water vapor permeability of the resulting polyurethane film is only 250 g / (m). 2• 24h), with a swelling rate as high as 28%, meaning that the moisture permeability and swelling resistance are significantly poor; when no irradiation crosslinking treatment is used (Comparative Example 3), the hydrophilic chains of PEG swell freely in water, and the swelling rate of the resulting polyurethane film is as high as 25.4%, with poor swelling resistance. Furthermore, due to the swelling and loosening of the hard segment micro-regions, the hydrostatic pressure also decreases.

[0078] (6) By comparing Examples 1-13 with Comparative Examples 5 and 6, it can be seen that by optimizing the raw material formulation and preparation process of polyurethane, this application can make the obtained polyurethane film have better mechanical properties. In contrast, the hydrostatic pressure of the polyurethane film (Comparative Example 5) and the polyurethane film prepared by one-step mixing in the prior art (Comparative Example 6) is not higher than 6500 mmH2O, and the mechanical properties are not good.

[0079] In summary, this application, through optimization of the raw material formulation and preparation process of polyurethane, enables the obtained polyurethane film to possess excellent anti-swelling and moisture permeability in addition to good mechanical properties, with a water vapor transmission rate ≥5000 g / (m²). 2 • 24h), swelling rate ≤ 8%, hydrostatic pressure ≥ 10000 mmH2O.

[0080] The applicant hereby declares that the above description is merely a specific embodiment of this application, but the scope of protection of this application is not limited thereto. Those skilled in the art should understand that any variations or substitutions that can be easily conceived by those skilled in the art within the scope of the technology disclosed in this application fall within the scope of protection and disclosure of this application.

Claims

1. A swelling-resistant and moisture-permeable polyurethane film, characterized in that, The raw materials for preparing the anti-swelling and breathable polyurethane film include a prepolymer containing terminal isocyanate groups, a chain extender, and a hydrophilic polyether polyol. The prepolymer containing terminal isocyanate groups is prepared by reacting polyether polyol and diisocyanate. The hydrophilic polyether polyol is polyethylene glycol; The swelling-resistant and moisture-permeable polyurethane film is a film that has undergone radiation crosslinking treatment.

2. The anti-swelling and moisture-permeable polyurethane film according to claim 1, characterized in that, The molar ratio of the polyether polyol to the diisocyanate is (0.03-0.15):

1.

3. The anti-swelling and moisture-permeable polyurethane film according to claim 1 or 2, characterized in that, The polyether polyols include polytetrahydrofuran diol and / or polyethylene glycol; And / or, the number average molecular weight of the polyether polyol is 1000-2500; And / or, the diisocyanate includes any one or a combination of at least two of 4,4'-diphenylmethane diisocyanate, isophorone diisocyanate or hexamethylene diisocyanate; And / or, the reaction is carried out at a temperature of 70-90°C for a time of 1-3 h.

4. The anti-swelling and moisture-permeable polyurethane film according to any one of claims 1-3, characterized in that, The chain extender includes monoallyl ethers of diols and small molecule diols; The monoallyl ether of the diol includes 3-allyloxy-1,2-propanediol; The content of the monoallyl ether of the diol is 5-10% of the total mass of the chain extender; The small molecule diols include any one or a combination of at least two of ethylene glycol, 1,4-butanediol, diethylene glycol monohydrate, or 1,6-hexanediol. And / or, the mass ratio of the chain extender to the hydrophilic polyether polyol is 1:(4-6).

5. The anti-swelling and moisture-permeable polyurethane film according to any one of claims 1-4, characterized in that, The number average molecular weight of the hydrophilic polyether polyol is 400-6000, preferably 1000-3000; And / or, the molar ratio of the hydrophilic polyether polyol to the diisocyanate is (0.1-0.4):

1.

6. The anti-swelling and moisture-permeable polyurethane film according to any one of claims 1-5, characterized in that, The absorbed dose of the irradiation crosslinking treatment is 5-50 kGy, preferably 15-40 kGy; And / or, the irradiation crosslinking treatment method includes electron beam irradiation and / or gamma ray irradiation.

7. A method for preparing an anti-swelling and moisture-permeable polyurethane film as described in any one of claims 1-6, characterized in that, The preparation method includes the following steps: A prepolymer containing terminal isocyanate groups, a chain extender, and a hydrophilic polyether polyol are melt-reacted, granulated, and cast to obtain an initial moisture-permeable film; the initial moisture-permeable film is then subjected to irradiation crosslinking treatment to obtain the anti-swelling moisture-permeable polyurethane film.

8. The preparation method according to claim 7, characterized in that, The melt reaction is carried out in a twin-screw extruder; And / or, the temperature of the melting reaction is 150-210°C; And / or, the granulation is carried out underwater; And / or, the granulation process further includes a drying step; after the drying process, the water content of the polyurethane particles obtained by granulation is ≤500 ppm; And / or, the casting process further includes a cooling step; And / or, the irradiation crosslinking treatment is carried out in a protective gas atmosphere; the protective gas includes any one or a combination of at least two of nitrogen, argon or helium.

9. The preparation method according to claim 7 or 8, characterized in that, The preparation method specifically includes the following steps: After mixing polyether polyol and diisocyanate in a molar ratio of (0.03-0.15):1, the mixture is reacted at 70-90℃ for 1-3 hours to obtain a prepolymer containing terminal isocyanate groups. The prepolymer containing terminal isocyanate groups, chain extender, and hydrophilic polyether polyol are melt-reacted in a twin-screw extruder at 150-210°C and granulated underwater to obtain polyurethane particles. The polyurethane particles are dried to a water content of ≤500 ppm, then cast and cooled to obtain an initial moisture-permeable film. The initial moisture-permeable film is then subjected to irradiation crosslinking treatment with an absorbed dose of 5-50 kGy under a protective gas atmosphere to obtain the anti-swelling moisture-permeable polyurethane film.

10. The use of an anti-swelling and breathable polyurethane film as described in any one of claims 1-6 in wound dressings.

Images