Medical sterilization package and preparation method thereof

Abstract

The invention discloses a medical sterilization package and a preparation method thereof, the medical sterilization package comprises a matrix film and a functional layer, the secant modulus of the matrix film according to ASTM D882 under 1% strain is 300-2000 MPa, the Talbot stiffness of the matrix film according to GB / T 23144 is 5-25 mN.m, and the air permeability of the matrix film according to GB / T 458 is 20-150 S / 100 mL. The functional layer is coated on the matrix film through at least two times of intaglio printing to form a discontinuous coating, the adjacent coatings form an overlapped structure, the resin content is gradually increased from inside to outside, and pattern projections of the coatings are at least partially staggered so as to form composite breathable pore channels with smaller sizes. The functional layer contains a thermo-sensitive block copolymer and 4, 4 '-oxybis (benzenesulfonyl hydrazide), so that the functional layer maintains low air permeability at room temperature so as to ensure sealing safety, and in an ethylene oxide sterilization temperature interval, a thermo-sensitive polymer chain shrinks and acts with a foaming agent to decompose and produce gas, so that air-permeable pores are expanded, the air permeability is improved, and the sterilization gas penetration effect is optimized.

Description

Technical Field

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

[0002] In medical device sterilization packaging, dialysis paper is widely used due to its excellent permeability to sterilizing gases such as ethylene oxide and its effective barrier properties against microorganisms. Traditional dialysis paper often uses a full-page coating process to form the functional layer. While this method can achieve effective sealing, the continuous heat-sealing resin layer covers most of the air-permeable micropores of the substrate, reducing the overall gas permeability of the material and affecting the penetration efficiency of sterilizing agents. This can easily lead to incomplete sterilization or prolonged desorption time, and increases the risk of bag bursting due to poor gas exchange between the inside and outside during the sterilization desorption process.

[0003] To improve air permeability, existing technologies have attempted to employ methods such as localized coating or transfer coating to form discontinuous resin layers on the substrate, thereby preserving air permeability channels. However, these methods still face challenges in practical applications. For example, the pattern design, coating precision, and uniformity control of dot-coating are difficult, making it challenging to achieve a high-density, highly uniform air-permeable pore structure while ensuring sufficient heat-sealing strength. Improper process control can easily lead to weak adhesion of functional layers or uneven air permeability, affecting the reliability and consistency of packaging.

[0004] Therefore, how to improve gas exchange efficiency, thereby reducing the difficulty of sterilization process and increasing the yield of finished packaging, while maintaining the necessary microbial barrier performance and heat sealing strength of sterilized packaging, has become a prominent technical problem. Summary of the Invention

[0005] The purpose of this invention is to solve at least one of the technical problems described in the background section.

[0006] To achieve the above objectives, the technical solution provided by the present invention is as follows.

[0007] In a first aspect, the present invention provides a medical sterilization packaging, comprising a functional layer and a base film stacked sequentially from the inside out; The substrate membrane has a secant modulus of 300~2000MPa at 1% strain according to ASTM D882, a Talber stiffness of 5~25mN·m according to GB / T23144, and an air permeability of 20~150S / 100mL according to GB / T458. The functional layer is formed into a discontinuous coating on the surface of the substrate film by at least two printing coatings. Each printing coating independently forms a layer of the discontinuous coating. The discontinuous coatings formed by adjacent printing coatings form a superimposed structure. In the superimposed structure, the resin content of the discontinuous coating increases from the inside to the outside. At room temperature, the air permeability of the discontinuous coating adjacent to the substrate membrane is less than the air permeability of the substrate membrane.

[0008] As a preferred technical solution, the functional layer comprises, by mass percentage, 25%~34% acrylic resin emulsion; 18%~32% thermosensitive block copolymer; 3.5%~8% 4,4'-oxobis(benzenesulfonylhydrazine); 3%~5% filler; 2%~4.5% polyethylene glycol; 0.5%~2% processing aid; and the balance being water.

[0009] As a preferred technical solution, the processing aid includes at least one of the following: leveling agent, initiator, stabilizer, and activator.

[0010] As a preferred technical solution, the temperature-sensitive block copolymer includes: PNIPAM-b-PBA, also known as poly(N-isopropylacrylamide)-block-poly(butyl acrylate); P(NIPAM-co-AAm)-bP(BA-co-HEMA), also known as poly(N-isopropylacrylamide-co-acrylamide)-block-poly(butyl acrylate-co-hydroxyethyl methacrylate); P(MEO2MA-co-OEGMA)-b-PEA, also known as poly(2-(2-methoxyethoxy)ethyl methacrylate-co-oligomeric (ethylene glycol) methacrylate)-block-poly(ethyl acrylate).

[0011] As a preferred technical solution, the polyethylene glycol is a terminal siloxane polyethylene glycol with a number average molecular weight in the range of 200 to 600.

[0012] As a preferred technical solution, the air permeability of the functional layer at 23℃±2℃ is A, and the air permeability at 55℃ is B. The thermal response air permeability change rate of the functional layer is calculated by [(BA) / A×100%], and the result is not less than 50%.

[0013] As a preferred technical solution, the patterns of the discontinuous coatings formed by two adjacent printing and coating processes are at least partially misaligned in the normal projection plane on the substrate film, so that the superimposed structure forms a composite air-permeable channel with a size smaller than the dot size of any discontinuous coating.

[0014] Secondly, the present invention provides a method for preparing medical sterilization packaging having any of the above-mentioned technical features, comprising the following steps: S01. An acrylic resin emulsion, a thermosensitive block copolymer, 4,4'-oxobis(benzenesulfonylhydrazine), a filler, polyethylene glycol and a processing aid are mixed to obtain a uniformly dispersed functional layer resin. S02. The functional layer resin is coated onto the surface of the substrate film using the first gravure printing unit to form the first discontinuous coating, and pre-curing is performed immediately. S03. The functional layer resin is coated onto the surface of the first discontinuous coating using the second gravure printing unit, and then immediately cured to obtain a composite film. S04. The composite membrane material is cured at a temperature of 20℃~30℃ and a humidity of 60%~80% for 12h~24h.

[0015] As a preferred technical solution, in step S02, the spacing between the arrayed pits on the printing roller of the first gravure printing unit is 50-100μm, and the pit depth is 30-80μm; in step S03, the spacing between the arrayed pits on the printing roller of the second gravure printing unit is 10-50μm, and the pit depth is 10-40μm.

[0016] As a preferred technical solution, in S02 and S03, the pre-curing and the final curing methods are independently selected from ultraviolet light curing, electron beam curing or hot air curing.

[0017] The advantages and beneficial effects of this invention are as follows: by using a substrate film and a superimposed structure formed by multiple printing coatings, the suitable modulus and stiffness of the substrate film ensure dimensional stability and smooth operation during high-precision gravure printing, providing a foundation for the precise transfer of the dot matrix coating; its high air permeability serves as a pathway for gas exchange. This invention, through at least two printing processes and a superimposed coating with resin content increasing from the inside out, forms a gradient sealing and breathable structure.

[0018] This invention maintains the integrity of the packaging seal while preserving a large number of uniform and fine air-permeable pores at the microscopic level due to the discontinuous nature of the functional layer resin and the superimposed structure between different layers. Under room temperature storage conditions, these pore structures remain stable, and the air permeability remains at a low level that meets the requirements for microbial barrier properties, thus ensuring the long-term sealing safety of the packaging. When the packaging undergoes ethylene oxide sterilization, the molecular chain contraction of the temperature-sensitive polymer in the functional layer and the gas production from the decomposition of 4,4'-oxobis(benzenesulfonylhydrazine) are activated, acting on the aforementioned microscopic pore structure, causing it to further expand or connect, thereby improving gas permeability. Attached Figure Description

[0019] Figure 1This is a schematic diagram of the structure of the medical sterilization packaging shown in this invention. Detailed Implementation

[0020] To make the above-mentioned objectives, features, and advantages of this application more apparent and understandable, the specific embodiments of this application will be described in detail below with reference to the accompanying drawings. It should be understood that the specific embodiments described herein are for illustrative purposes only and are not intended to limit the scope of this application. Furthermore, it should be noted that, for ease of description, only the parts relevant to this application are shown in the accompanying drawings, not the entire structure. Based on the embodiments in this application, all other embodiments obtained by those skilled in the art without inventive effort are within the scope of protection of this application.

[0021] The terms “comprising” and “having”, and any variations thereof, used in this application are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the steps or units listed, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to such process, method, product, or apparatus.

[0022] In this document, the term "embodiment" means that a particular feature, structure, or characteristic described in connection with an embodiment may be included in at least one embodiment of this application. The appearance of this phrase in various places throughout the specification does not necessarily refer to the same embodiment, nor is it a separate or alternative embodiment mutually exclusive with other embodiments. It will be explicitly or implicitly understood by those skilled in the art that the embodiments described herein can be combined with other embodiments.

[0023] This invention provides a medical sterilization packaging, comprising a functional layer and a base film stacked sequentially from the inside out. The base film has a secant modulus of 300-2000 MPa at 1% strain according to ASTM D882, a Taber stiffness of 5-25 mN·m according to GB / T 23144, and an air permeability of 20-150 S / 100mL according to GB / T 458. The functional layer is formed into a discontinuous coating on the surface of the base film by at least two printing coatings. Each printing coating independently forms a discontinuous coating layer, and the discontinuous coatings formed by adjacent sequential printing coatings form a superimposed structure. In this superimposed structure, the resin content of the discontinuous coatings increases from the inside out. At room temperature, the air permeability of adjacent discontinuous coatings of the base film is less than the air permeability of the base film.

[0024] In this invention, the medical sterilization packaging relies not only on the inherent properties of a single material, but also on the composite structure and dynamic response mechanism constructed through a specific process between the base membrane and the functional layer. The base membrane, acting as a supporting framework, balances mechanical and permeability properties; the functional layer, as an intelligent response unit, provides a gradient seal and a microscopic permeable pore network through a superimposed structure formed by at least two printing coatings, achieving regulation of gas permeation behavior during storage and sterilization.

[0025] The secant modulus of the base film is set between 300 and 2000 MPa to maintain dimensional stability and flatness during coating. When the modulus is below 300 MPa, the film is prone to plastic deformation or creep under printing tension, leading to distortion of the coating pattern, misregistration, and difficulty in accurately constructing the dot structure of subsequent functional layers. When the modulus is above 2000 MPa, the film becomes rigid. Although dimensionally stable, its flexibility decreases, making it prone to micro-cracks due to bending during subsequent bag making, heat sealing, or instrument loading, thus compromising packaging integrity. Preferably, the secant modulus of the base film is in the range of 800 to 1500 MPa.

[0026] The stiffness of the film, controlled between 5 and 25 mN·m, directly affects the formability, stacking stability, and smoothness of film feeding on automated production lines. When the stiffness is below 5 mN·m, the film is too soft, easily causing swaying and sticking during high-speed printing and bag making, leading to uneven coating or poor heat sealing. Furthermore, the finished packaging lacks firmness and is easily deformed under pressure during warehousing and transportation. When the stiffness is above 25 mN·m, the film is too rigid, not only reducing the flexibility of the packaging and making it difficult to adapt to the packaging needs of irregularly shaped instruments, but also potentially causing "blank coating" or "incomplete printing" during the printing process due to poor adhesion to the printing rollers.

[0027] The air permeability value (S / 100mL) indicates the time required for 100mL of air to pass through a specified area. The higher the value, the worse the air permeability. If the air permeability is less than 20 S / 100mL, it means that the substrate itself is too porous. Although it is conducive to the rapid passage of gas, its ability to block microorganisms (especially bacterial spores) at room temperature may be insufficient, making it difficult to meet the primary barrier requirements for medical device packaging.

[0028] The functional layer, by mass percentage, comprises: 25%–34% acrylic resin emulsion; 18%–32% thermosensitive block copolymer; 3.5%–8% 4,4'-oxobis(benzenesulfonylhydrazine); 3%–5% filler; 2%–4.5% polyethylene glycol; 0.5%–2% processing aids; and the balance being water. The acrylic resin emulsion, as the continuous phase and film-forming substance of the functional layer, primarily provides the coating with mechanical strength, adhesion to the substrate film, and ultimately, heat-sealing performance. Its content directly affects the integrity of the coating and the carrying capacity of the functional components. If the content is too low, the coating cannot form a continuous, dense film, leading to easy migration or detachment of functional components (such as thermosensitive polymers and foaming agents), resulting in poor mechanical properties and insufficient heat-sealing strength. If the content is too high, there is too much resin phase, which overfills and covers the micropores formed by discontinuous coating. Even if the functional components are activated at high temperatures, the air permeability channels are difficult to open effectively, weakening the overall air permeability response.

[0029] The glass transition temperature (Tg) of acrylic resin emulsion is best selected between -10℃ and 20℃, which can provide moderate flexibility at room temperature and good melt flow at heat sealing temperature.

[0030] Thermosensitive block copolymers are obtained by block copolymerization of hydrophilic segments (such as poly(N-isopropylacrylamide), PNIPAM) with well-defined low critical solution temperatures (LCSTs) and hydrophobic segments that provide flexibility and compatibility with the matrix resin. At room temperature below their LCSTs, the hydrophilic segments extend through hydrogen bonding with water molecules, resulting in a stretched polymer chain with good compatibility with the acrylic resin matrix and low gas permeability in the functional layer. When the temperature rises to the sterilization range and exceeds the LCST, the hydrophilic segments dehydrate, the hydrogen bonds break, and the segments undergo entropy-driven, rapid contraction and aggregation, transitioning from a hydrophilic to a hydrophobic state.

[0031] The aforementioned phase transition process generates conformational changes and shrinkage stresses in the polymer chains. These stresses are transmitted to the surrounding acrylic resin matrix, causing micro-deformation of the matrix and thus widening or expanding pre-existing micro-defects or porosity between dots in the coating. The content of the temperature-sensitive polymer needs to be sufficient to ensure the formation of an effective stress transfer network within the coating; however, it should not be too high to avoid excessively affecting the film-forming continuity and heat-sealing reliability of the coating.

[0032] In some embodiments, 4,4'-oxobis(benzenesulfonylhydrazine) is used as an organic foaming agent, and its thermal decomposition temperature is typically above 120°C. When the ambient temperature rises to the ethylene oxide sterilization temperature, the shrinkage of the aforementioned temperature-sensitive polymer chains creates localized stress concentration points within the coating. The 4,4'-oxobis(benzenesulfonylhydrazine) particles dispersed in the resin matrix are more easily "activated," and the activation energy barrier of their decomposition reaction is effectively lowered, allowing for partial or selective decomposition below their standard decomposition temperature, releasing small molecule gases such as nitrogen and water vapor. These in-situ generated gases create minute internal pressures within the coating. This pressure effect, combined with the tensile stress generated by the shrinkage of the temperature-sensitive polymer chains, acts on weak areas or pre-placed pores in the coating, more effectively promoting the expansion and interconnection of these areas, thereby significantly increasing the size and connectivity of the effective air permeability channels.

[0033] In some embodiments, fillers such as nano-silica, modified kaolin, or precipitated barium sulfate primarily serve to regulate the physical properties of the coating, helping to maintain the stability of the dot shape and pore structure during coating and curing, and preventing excessive flow of liquid resin under gravity or capillary action that could lead to pore closure.

[0034] This invention preferably uses terminal siloxane-based polyethylene glycol (PEG) with a number-average molecular weight in the range of 200 to 600 as a small-molecule plasticizer, which can improve the low-temperature film-forming properties of acrylic resin emulsions and the flexibility of coatings. Secondly, its PEG segments have a certain degree of hydrophilicity, which helps to regulate the wetting characteristics of the coating surface. Most importantly, during the coating curing process, its terminal siloxane groups can chemically react or strongly interact with the active groups in the acrylic resin or with the polar groups on the substrate film surface, thereby enhancing the interfacial bonding between the functional layer and the substrate film.

[0035] Processing aids (0.5%~2%) include at least one of leveling agents, initiators, stabilizers, and activators. Leveling agents improve the rheological properties of the resin coating solution, ensuring uniform transfer and the formation of well-defined dot patterns during gravure printing. Initiators initiate the cross-linking reaction of the resin during pre-curing and final curing steps. Stabilizers prevent sedimentation, flocculation, or premature reaction of the components during storage and processing.

[0036] It is particularly important to note that the activator is used to activate 4,4'-oxobis(benzenesulfonylhydrazine), lowering its thermal decomposition initiation temperature and making it more readily decomposed in response to the stress generated by the shrinkage of the thermosensitive polymer within the sterilization temperature range. Suitable activators can be organic acids (such as stearic acid), metal soaps (such as zinc stearate), or preferably amine compounds.

[0037] The thermal response permeability change rate of the functional layer is required by this invention to be no less than 50%. This indicator shows that the packaging's gas permeability is substantially improved when it moves from a room temperature storage environment to a high-temperature sterilization environment, thereby ensuring that the ethylene oxide sterilizing gas can efficiently penetrate the packaging and enter the interior, and that the residual gas can also be quickly decomposed and escaped after sterilization. Preferably, by optimizing the above component ratios and coating structure, this change rate can reach 80% to 200% or even higher.

[0038] This invention abandons traditional full-page coating or simple single-stage partial coating, and instead employs at least two gravure printing coatings to construct the functional layer. Each print forms a patterned, discontinuous coating on the substrate film, such as an array of regularly arranged circular, square, or polygonal "dots." Between the dots are areas of the substrate film not covered by the coating, forming the initial ventilation windows.

[0039] The key point is that the discontinuous coatings formed by two adjacent printing coats have at least partial misalignment in their normal projection planes on the substrate film. This means that the dots of the second (or subsequent) layer dot are not completely and precisely overlaid on the dots of the first layer, but are offset or rotated to some extent.

[0040] This staggered, superimposed structure, combined with a gradient of resin content increasing from the inside out, creates composite pores in the superimposed region that are smaller than the size of any single-layer discontinuous coating dot. Specifically, the gas penetration path is no longer simply through the opening of a single layer of dots perpendicularly, but rather requires a circuitous route through the edge of the first layer of dots, gaps not completely covered by the second layer of dots, and the even narrower gap formed by the superposition of the two coatings.

[0041] At room temperature, these tiny and tortuous channels significantly increase the difficulty for microorganisms to penetrate via Brownian motion, effectively improving the microbial barrier performance and meeting the storage safety requirements of medical packaging. Simultaneously, the tortuous path also increases the mean free path of gas molecules, resulting in a lower permeability A.

[0042] Under high-temperature sterilization conditions, the shrinkage of the temperature-sensitive polymer and the gas-generating effect of the foaming agent primarily act on the narrowest and most stress-concentrated "bottleneck" regions of these composite channels. These regions are extremely small, and even minute deformations can cause changes in the permeable cross-sectional area (according to Poiseuille's law, flow rate is proportional to the fourth power of the channel radius). Therefore, relatively small stimuli can trigger a surge in permeability B, achieving a highly efficient and sensitive temperature response.

[0043] Secondly, the present invention provides a method for preparing the above-mentioned medical sterilization packaging, comprising the following steps: S01. A uniformly dispersed functional layer coating resin solution is prepared by mixing acrylic resin emulsion, thermosensitive block copolymer, 4,4'-oxobis(benzenesulfonylhydrazine), filler, polyethylene glycol, and processing aids. In this step, it is generally recommended to first mix water, acrylic resin emulsion, polyethylene glycol, and half of the processing aids (such as stabilizers and leveling agents) at a low speed until homogeneous. Then, the thermosensitive block copolymer (in emulsion form) and filler are slowly added, and the stirring speed is increased to ensure thorough dispersion. Finally, the 4,4'-oxobis(benzenesulfonylhydrazine) powder and the remaining processing aids are added, and the mixture is stirred until homogeneous while avoiding the introduction of excessive air bubbles. The entire mixing process should preferably be carried out at room temperature or slightly below room temperature to prevent premature reaction of the functional components.

[0044] S02. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then pre-cured immediately. The surface of the printing roller of the first gravure printing unit is engraved with an array of pits. The shape, depth and spacing of these pits determine the dot morphology and coating amount of the first coating layer.

[0045] In some preferred embodiments of the present invention, the spacing between the arrayed pits on the first printing roller is 50-100 μm, and the pit depth is 30-80 μm. A larger pit spacing and depth facilitates the formation of a first-layer base dot structure with a larger initial ventilation window. Pre-curing immediately after coating aims to rapidly gel or initially cross-link the coating surface, fixing the shape and position of the dots and giving it sufficient mechanical strength to withstand the pressure of the printing roller and the slight erosion of the resin liquid during the subsequent second coating layer, preventing the two patterns from fusing together and losing their misaligned structure.

[0046] S03. The functional layer resin liquid is applied to the surface of the first discontinuous coating using the second gravure printing unit, and then immediately cured to obtain a composite film. The printing roller of the second gravure printing unit has a similar pit pattern design to the first printing roller but different parameters to achieve staggered superposition.

[0047] In some preferred embodiments, the spacing between the arrayed pits on the second printing roller is 10-50 μm, and the pit depth is 10-40 μm. Smaller spacing and shallower depth mean that the second coating layer will be superimposed on the first layer in the form of finer, denser dots. Furthermore, due to the control of printing accuracy, it will inevitably form partial misalignment with the dots of the first layer, thus constructing the composite permeable channels described above. The final curing after coating aims to completely cross-link and cure the two coating layers, forming a unified and robust functional layer structure.

[0048] S04. Curing the composite membrane material at a temperature of 20℃~30℃ and a humidity of 60%~80% for 12h~24h. The polymer chains within the newly cured coating may be in a non-equilibrium state, exhibiting internal stress. Curing under suitable temperature and humidity conditions helps relax the polymer chains, release residual stress, and further strengthen the interfacial bonding between the coating and the substrate membrane. Simultaneously, this allows the temperature-sensitive polymer chains to reach their stable equilibrium conformation at room temperature, ensuring that the air permeability of the packaging remains stable at the designed low level during the initial storage period. The curing environment should be kept clean to avoid dust contamination.

[0049] The medical sterilization packaging of this invention is particularly suitable for the final packaging of surgical instruments, catheters, orthopedic implants, precision electronic medical devices, etc. During ambient temperature storage and transportation, the packaging relies on the moderate air permeability of the base film itself and the fine, tortuous composite pores formed by the discontinuous coating of the functional layer to effectively block microorganisms and ensure the sterility and safety of the internal instruments.

[0050] When the package enters the ethylene oxide sterilizer and the ambient temperature rises to the set sterilization temperature (e.g., 55°C), the thermosensitive block copolymer segments in the functional layer undergo phase transition shrinkage. Simultaneously, 4,4'-oxobis(benzenesulfonylhydrazine) decomposes and releases gas under the action of the activator and localized stress, causing a reversible change in the microstructure of the functional layer. This expands the composite permeable channels and increases the overall permeability of the packaging. This allows ethylene oxide gas to penetrate the packaging quickly and uniformly, effectively sterilizing the internal instruments. After the sterilization process, during the desorption phase, even if the temperature may not have completely dropped to room temperature, the packaging maintains a high permeability, which facilitates the rapid diffusion of residual ethylene oxide gas, thereby shortening the overall sterilization desorption cycle and reducing the risk of bag bursting due to residual gas.

[0051] The present invention will be further explained and illustrated below with reference to specific embodiments.

[0052] Example 1 This embodiment provides a method for preparing medical sterilization packaging.

[0053] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 550 MPa at 1% strain according to ASTM D882, a Taber stiffness of 8.2 mN·m according to GB / T 23144, and an air permeability of 45 S / 100mL according to GB / T 458.

[0054] S02. By mass percentage, mix 30% acrylic resin emulsion, 20% thermosensitive block copolymer PNIPAM-b-PBA, 4.5% 4,4'-oxobis(benzenesulfonylhydrazine), 4% filler nano silica, 3% polyethylene glycol, and 1.5% processing aid (including leveling agent) with water to obtain a uniformly dispersed functional layer resin liquid.

[0055] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with ultraviolet light. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 60μm, and the pit depth is 35μm.

[0056] S04. The functional layer resin liquid is coated onto the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured with ultraviolet light to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 30 μm, and the pit depth is 15 μm. The patterns of the discontinuous coatings formed by adjacent printing coatings are partially misaligned in their normal projection onto the substrate film, resulting in a composite permeable channel formed by the superimposed structure.

[0057] S05. The composite film material is cured at 25°C and 70% humidity for 18 hours to obtain medical sterilized packaging.

[0058] The medical sterilization packaging prepared in this embodiment has an air permeability A of 110 S / 100mL at 23°C and an air permeability B of 180 S / 100mL at 55°C, with a thermal response air permeability change rate of approximately 63.6%.

[0059] Example 2 This embodiment provides a method for preparing medical sterilization packaging.

[0060] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 1850 MPa at 1% strain according to ASTM D882, a Taber stiffness of 21 mN·m according to GB / T 23144, and an air permeability of 130 S / 100mL according to GB / T 458.

[0061] S02. By mass percentage, 28% acrylic resin emulsion, 22% thermosensitive block copolymer P(MEO2MA-co-OEGMA)-b-PEA, 5.5% 4,4'-oxobis(benzenesulfonylhydrazine), 3.5% filler precipitated barium sulfate, 2.5% polyethylene glycol, and 1.2% processing aids (including initiator) are mixed with water to obtain a uniformly dispersed functional layer resin liquid.

[0062] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with hot air. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 95μm, and the pit depth is 75μm.

[0063] S04. The functional layer resin liquid is applied to the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured by electron beam to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 45 μm, and the pit depth is 38 μm. The patterns of the discontinuous coatings formed by adjacent printing coats are partially misaligned in the normal projection plane of the substrate film.

[0064] S05. The composite film material is cured at 22°C and 65% humidity for 22 hours to obtain medical sterilized packaging.

[0065] The medical sterilization packaging prepared in this embodiment has an air permeability A of 85 S / 100mL at 23°C and an air permeability B of 150 S / 100mL at 55°C, with a thermal response air permeability change rate of approximately 76.5%.

[0066] Example 3 This embodiment provides a method for preparing medical sterilization packaging.

[0067] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 1200 MPa at 1% strain according to ASTM D882, a Taber stiffness of 15 mN·m according to GB / T 23144, and an air permeability of 90 S / 100 mL according to GB / T 458.

[0068] S02. By mass percentage, 33% acrylic resin emulsion, 19% thermosensitive block copolymer P(NIPAM-co-AAm)-bP(BA-co-HEMA), 4% 4,4'-oxobis(benzenesulfonylhydrazine), 4.5% kaolin filler, 3.8% polyethylene glycol, and 1% processing aid (including stabilizer) are mixed with water to obtain a uniformly dispersed functional layer resin liquid.

[0069] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with an electron beam. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 80 μm, and the pit depth is 50 μm.

[0070] S04. The functional layer resin liquid is applied to the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured with hot air to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 20 μm, and the pit depth is 12 μm. The patterns of the discontinuous coatings formed by adjacent printing coats are partially misaligned in the normal projection plane of the substrate film.

[0071] S05. The composite film material is cured at 28°C and 75% humidity for 15 hours to obtain medical sterilized packaging.

[0072] The medical sterilization packaging prepared in this embodiment has an air permeability A of 95 S / 100mL at 23°C and an air permeability B of 175 S / 100mL at 55°C, with a thermal response air permeability change rate of approximately 84.2%.

[0073] Example 4 This embodiment provides a method for preparing medical sterilization packaging.

[0074] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 900 MPa at 1% strain according to ASTM D882, a Taber stiffness of 12 mN·m according to GB / T 23144, and an air permeability of 65 S / 100mL according to GB / T 458.

[0075] S02. By mass percentage, 29% acrylic resin emulsion, 25% thermosensitive block copolymer PNIPAM-b-PBA, 5.5% 4,4'-oxobis(benzenesulfonylhydrazine), 4% filler nano-calcium carbonate, 3% number-average molecular weight 300 terminal siloxane polyethylene glycol, and 1.5% processing aids (including leveling agent and activator) are mixed with water to obtain a uniformly dispersed functional layer resin liquid.

[0076] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with ultraviolet light. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 70 μm, and the pit depth is 40 μm.

[0077] S04. The functional layer resin liquid is applied to the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured with ultraviolet light to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 25 μm, and the pit depth is 18 μm. The patterns of the discontinuous coatings formed by adjacent printing coatings are partially misaligned in the normal projection plane of the substrate film.

[0078] S05. The composite film material is cured at 26°C and 72% humidity for 20 hours to obtain medical sterilized packaging.

[0079] The medical sterilization packaging prepared in this embodiment has an air permeability A of 70 S / 100mL at 23°C and an air permeability B of 140 S / 100mL at 55°C, with a thermal response air permeability change rate of 100%.

[0080] Example 5 This embodiment provides a method for preparing medical sterilization packaging.

[0081] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 750 MPa at 1% strain according to ASTM D882, a Taber stiffness of 18 mN·m according to GB / T 23144, and an air permeability of 110 S / 100 mL according to GB / T 458.

[0082] S02. By mass percentage, mix 32% acrylic resin emulsion, 20% thermosensitive block copolymer P(NIPAM-co-AAm)-bP(BA-co-HEMA), 4% 4,4'-oxobis(benzenesulfonylhydrazine), 3.5% kaolin filler, 4.5% siloxane-terminated polyethylene glycol with a number average molecular weight of 500, and 2% processing aids (including initiator, stabilizer, and activator) with water to obtain a uniformly dispersed functional layer resin liquid.

[0083] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with hot air. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 55μm, and the pit depth is 60μm.

[0084] S04. The functional layer resin liquid is applied to the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured with hot air to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 15μm, and the pit depth is 25μm. The patterns of the discontinuous coatings formed by adjacent printing coatings are partially misaligned in their normal projection onto the substrate film, resulting in a composite breathable channel with smaller size in the superimposed structure.

[0085] S05. The composite film material is cured at 23°C and 68% humidity for 24 hours to obtain medical sterilized packaging.

[0086] The medical sterilization packaging prepared in this embodiment has an air permeability A of 60 S / 100mL at 23°C, an air permeability B of 132 S / 100mL at 55°C, and a thermal response air permeability change rate of 120%.

[0087] Example 6 This embodiment provides a method for preparing medical sterilization packaging.

[0088] S01. Prepare the substrate membrane. The substrate membrane has a secant modulus of 1500 MPa at 1% strain according to ASTM D882, a Taber stiffness of 9 mN·m according to GB / T 23144, and an air permeability of 35 S / 100mL according to GB / T 458.

[0089] S02. By mass percentage, mix 26% acrylic resin emulsion, 30% thermosensitive block copolymer P(MEO2MA-co-OEGMA)-b-PEA, 7.5% 4,4'-oxobis(benzenesulfonyl hydrazine), 4.5% filler nano-silica, 2.5% terminal siloxane polyethylene glycol with a number average molecular weight of 200, and 0.8% processing aids (including leveling agent, stabilizer, and activator) with water to obtain a uniformly dispersed functional layer resin liquid.

[0090] S03. The functional layer resin liquid is applied to the surface of the substrate film using the first gravure printing unit to form a first discontinuous coating, and then immediately pre-cured with an electron beam. The spacing between the arrayed pits on the printing roller of the first gravure printing unit is 90 μm, and the pit depth is 70 μm.

[0091] S04. The functional layer resin liquid is coated onto the surface of the first discontinuous coating using a second gravure printing unit, and then immediately cured by electron beam to obtain a composite film. The spacing between the arrayed pits on the printing roller of the second gravure printing unit is 40 μm, and the pit depth is 32 μm. The patterns of the discontinuous coatings formed by two adjacent printing coatings are completely misaligned in their normal projection planes on the substrate film, resulting in a composite pore structure with a size significantly smaller than the dot size of any discontinuous coating.

[0092] S05. The composite film material is cured at 30°C and 80% humidity for 12 hours to obtain medical sterilized packaging.

[0093] The medical sterilization packaging prepared in this embodiment has an air permeability A of 125 S / 100mL at 23°C and an air permeability B of 250 S / 100mL at 55°C, with a thermal response air permeability change rate of 100%.

[0094] Comparative Example 1 This comparative example is a commercially available sterile packaging (full-coated type) for ordinary medical dialysis paper. Its substrate is medical dialysis paper with a continuous heat-sealing resin layer coated on the surface.

[0095] The packaging has an air permeability of 180 S / 100mL at 23°C and 195 S / 100mL at 55°C, with a thermal response air permeability change rate of approximately 8.3%.

[0096] Comparative Example 2 This comparative example provides a method for preparing medical packaging, the main difference from Example 1 being that the functional layer is formed by a single gravure printing coating to form a single discontinuous coating, without forming a superimposed structure.

[0097] S01. Prepare the same substrate membrane as in Example 1.

[0098] S02. Prepare the same functional layer resin solution as in Example 1.

[0099] S03. A single gravure printing unit is used to coat the functional layer resin liquid onto the surface of the substrate film to form a single-layer discontinuous coating, which is then immediately cured with ultraviolet light. The printing roller parameters are the same as those of the first printing roller in Example 1.

[0100] S04. The membrane material is cured under the same conditions as in Example 1 to obtain medical packaging.

[0101] The medical packaging prepared in this comparative example has an air permeability A of 80 S / 100mL at 23℃ and an air permeability B of 110 S / 100mL at 55℃, with a thermal response air permeability change rate of approximately 37.5%.

[0102] Comparative Example 3 This comparative example provides a method for preparing medical packaging, the main difference from Example 4 being that the functional layer formulation does not contain thermosensitive block copolymers and 4,4'-oxobis(benzenesulfonylhydrazine).

[0103] S01. Prepare the same substrate membrane as in Example 4.

[0104] S02. By mass percentage, 60% acrylic resin emulsion, 4% nano calcium carbonate filler, 3% siloxane-terminated polyethylene glycol with a number average molecular weight of 300, and 1.5% processing aid (containing only leveling agent) are mixed with water to obtain a uniformly dispersed resin liquid.

[0105] S03, the coating, curing and aging steps are the same as in Example 4.

[0106] The medical packaging prepared in this comparative example has an air permeability A of 150 S / 100mL at 23℃ and an air permeability B of 155 S / 100mL at 55℃, with a thermal response air permeability change rate of approximately 3.3%.

[0107] The packaging materials prepared in Examples 1-6 were compared with those in Comparative Examples 1-3 in terms of performance. The results showed that the packaging materials of the present invention maintained low air permeability (A value) at room temperature, ensuring sealing safety and microbial barrier properties. At a simulated sterilization temperature of 55°C, the air permeability (B value) increased, with thermal response air permeability changes of no less than 50%, reaching a maximum of 120%. In contrast, the commercially available product in Comparative Example 1 showed an extremely low change rate; Comparative Example 2, lacking a superimposed structure, had an insufficient change rate; and Comparative Example 3, lacking temperature-sensitive and foaming functional components, showed almost no response.

[0108] The above embodiments merely illustrate several implementation methods of the present invention, and their descriptions are relatively specific and detailed, but they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A medical sterilization packaging, characterized in that, It includes functional layers and a substrate membrane stacked sequentially from the inside out; The substrate membrane has a secant modulus of 300~2000MPa at 1% strain according to ASTM D882, a Talbot stiffness of 5~25 mN·m according to GB / T 23144, and an air permeability of 20~150 S / 100mL according to GB / T 458. The functional layer is formed into a discontinuous coating on the surface of the substrate film by at least two printing coatings. Each printing coating independently forms a layer of the discontinuous coating. The discontinuous coatings formed by adjacent printing coatings form a superimposed structure. In the superimposed structure, the resin content of the discontinuous coating increases from the inside to the outside. At room temperature, the air permeability of the discontinuous coating adjacent to the substrate membrane is less than the air permeability of the substrate membrane.

2. The medical sterilization packaging according to claim 1, characterized in that, The functional layer comprises, by weight percentage, 25%–34% acrylic resin emulsion; 18%–32% thermosensitive block copolymer; 3.5%–8% 4,4'-oxobis(benzenesulfonylhydrazine); 3%–5% filler; 2%–4.5% polyethylene glycol; 0.5%–2% processing aids; and the balance being water.

3. The medical sterilization packaging according to claim 2, characterized in that, The processing aids include at least one of leveling agents, initiators, stabilizers, and activators.

4. The medical sterilization packaging according to claim 2, characterized in that, The thermosensitive block copolymer includes at least one of PNIPAM-b-PBA, P(NIPAM-co-AAm)-bP(BA-co-HEMA), and P(MEO2MA-co-OEGMA)-b-PEA.

5. The medical sterilization packaging according to claim 2, characterized in that, The polyethylene glycol is a terminal siloxane polyethylene glycol with a number average molecular weight in the range of 200 to 600.

6. The medical sterilization packaging according to claim 1, characterized in that, The air permeability of the functional layer at 23℃±2℃ is A, and the air permeability at 55℃ is B. The thermal response air permeability change rate of the functional layer is calculated by [(BA) / A×100%], and the result is not less than 50%.

7. The medical sterilization packaging according to claim 1, characterized in that, The patterns of the discontinuous coatings formed by two adjacent printing coats are at least partially misaligned in their normal projection onto the substrate film, such that the superimposed structure forms composite pores with a size smaller than the dot size of any discontinuous coating.

8. A method for preparing medical sterilized packaging as described in any one of claims 1-7, characterized in that, Includes the following steps: S01. An acrylic resin emulsion, a thermosensitive block copolymer, 4,4'-oxobis(benzenesulfonylhydrazine), a filler, polyethylene glycol and a processing aid are mixed to obtain a uniformly dispersed functional layer resin. S02. The functional layer resin is coated onto the surface of the substrate film using the first gravure printing unit to form the first discontinuous coating, and pre-curing is performed immediately. S03. The functional layer resin is coated onto the surface of the first discontinuous coating using the second gravure printing unit, and then immediately cured to obtain a composite film. S04. The composite membrane material is cured at a temperature of 20℃~30℃ and a humidity of 60%~80% for 12h~24h.

9. The method according to claim 8, characterized in that, In step S02, the spacing between the arrayed pits on the printing roller of the first gravure printing unit is 50-100μm, and the pit depth is 30-80μm; in step S03, the spacing between the arrayed pits on the printing roller of the second gravure printing unit is 10-50μm, and the pit depth is 10-40μm.

10. The method according to claim 8, characterized in that, In steps S02 and S03, the pre-curing and final curing methods are independently selected from ultraviolet light curing, electron beam curing, or hot air curing.

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