High-low temperature PE (polyethylene) film for packaging medical equipment and processing method of high-low temperature PE film

Abstract

The invention discloses a high-low temperature PE film for medical instrument packaging and a processing method thereof.The PE film is of a three-layer or five-layer co-extrusion structure, a bag can be directly made without compounding, and the PE film comprises a heat sealing layer, a middle layer and an outer layer which are sequentially arranged from inside to outside; the heat sealing layer is a low-temperature heat sealing layer and consists of a mixture of POE (Polyolefin Elastomer) metallocene, KN resin and metallocene polyethylene; the number of the middle layers is 1-3, and the middle layers are composed of a mixture of a high-density metallocene material, HDPE and medium-density polyethylene. And the outer layer consists of a mixture of high-density metallocene polyethylene, LDPE (Low-Density Polyethylene) and an anti-blocking agent. Through the co-extrusion structure, direct bag making without compounding is achieved, the process is simplified, cost is reduced, and the problems of traditional complex compounding and layering are solved; the specific raw material ratio of each layer realizes low-temperature heat sealing, high strength and good opening property, and avoids instrument damage, film damage and adhesion.

Description

Technical Field

[0001] This invention relates to the field of medical device packaging, and in particular to a high and low temperature PE film for medical device packaging and its processing method. Background Technology

[0002] Medical device packaging places extremely stringent performance requirements on the film. It must not only meet the protection needs during transportation and storage but also be compatible with sterilization processes (such as ethylene oxide sterilization) and visual inspection requirements. Currently, existing PE films for medical device packaging have several technical limitations:

[0003] Traditional PE films often employ single-layer or simple composite structures. The heat-sealing temperature of the heat-sealing layer is relatively high, leading to issues like sticking and clogging during heat sealing, resulting in low packaging efficiency and damaged appearance. During the ethylene oxide sterilization process at around 50°C, the strong intermolecular forces on the outer surface can cause film-bag adhesion, affecting subsequent unpacking and use. Insufficient temperature resistance means that wrinkles easily appear after heat sealing due to temperature fluctuations, making it impossible to maintain packaging flatness. To meet temperature resistance and strength requirements, composites with other materials are often necessary, increasing production processes and costs, and potentially causing packaging failure due to delamination between composite layers.

[0004] In addition, existing PE films have poor transparency and exhibit problems such as watermarks and crystal points, which are not suitable for visual inspection of medical devices before and after sterilization. At the same time, the overall strength and toughness of the film are insufficient, and it is easy to be scratched or torn during transportation and handling, which affects the sterile protection of medical devices. Therefore, a high and low temperature PE film for medical device packaging and its processing method are proposed. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this invention provides a high-low temperature PE film for medical device packaging and its processing method, thereby solving the problems mentioned in the background section.

[0006] To achieve the above objectives, the present invention provides the following technical solution: a high and low temperature PE film for medical device packaging, comprising:

[0007] The PE film has a three- or five-layer co-extruded structure, which can be directly used to make bags without lamination. It includes a heat-sealing layer, an intermediate layer and an outer layer arranged from the inside to the outside. This structure gives the film good interlayer bonding and overall stability, avoids the potential risk of glue residue to medical devices in the lamination process, and simplifies the production process and improves production efficiency.

[0008] The heat-sealing layer is a low-temperature heat-sealing layer composed of a mixture of POE elastomer metallocene, KN resin, and metallocene polyethylene. The total mass percentage of POE elastomer metallocene, KN resin, and metallocene polyethylene in the mixture is 100%. It is used to achieve PE self-sealing, heat-sealing Tyvek functions, and low-temperature heat sealing at 80-120℃, with a heat-sealing strength of not less than 1.5N / 15mm. This formulation enables the heat-sealing layer to achieve good heat-sealing effect at a lower temperature, reducing thermal damage to medical devices during the heat-sealing process, while improving heat-sealing strength and sealing reliability, effectively preventing contamination of medical devices during storage and transportation.

[0009] The intermediate layer consists of 1-3 layers and is composed of a mixture of high-density metallocene material, HDPE, and medium-density polyethylene. The total mass percentage of high-density metallocene material, HDPE, and medium-density polyethylene in the mixture is 100%. This mixture is used to improve the overall temperature resistance of the film and to keep the film tough and non-brittle within the temperature range of -40℃ to 80℃. This formulation gives the intermediate layer high strength and rigidity, improves the puncture resistance and tear resistance of the film, and can effectively protect medical devices from external damage during packaging, transportation, and use, while ensuring the dimensional stability of the film.

[0010] The outer layer is composed of a mixture of high-density metallocene polyethylene, LDPE, and an opening agent. The opening agent consists of inorganic particles with a particle size of 0.5-5 μm. The total mass percentage of high-density metallocene polyethylene, LDPE, and the opening agent in the mixture is 100%. This mixture is used to achieve temperature resistance, prevent sticking to the knife during heat sealing, and prevent the film bags from sticking together when stacked. It also prevents the film bags from sticking together during ethylene oxide sterilization at around 50°C. This formula provides the outer layer with good opening and slip properties, preventing the film from sticking together during storage and use. This facilitates the operation of automatic packaging equipment and improves packaging efficiency. At the same time, the use of inorganic particle opening agents does not affect the transparency and appearance quality of the film.

[0011] The PE film has high overall transparency, no obvious watermarks, streaks or crystal points, and is flat and wrinkle-free after heat sealing. It can withstand friction during transportation and handling without scratches or bag breakage.

[0012] During the drying process, the raw materials are placed in a drying oven and the temperature is set to 40-50℃ for 2-3 hours to remove free moisture. The sieving process uses an 80-100 mesh screen. The raw materials are poured into the screen and mechanical impurities and particles exceeding the standard size are filtered out by means of vibration, etc., to avoid the formation of crystal points during plasticization.

[0013] The three- or five-layer co-extruded structure eliminates the need for lamination, allowing for direct bag production and simplifying the process. The heat-sealing layer mixture achieves PE self-sealing, heat sealing with Tyvek, and low-temperature heat sealing while meeting strength standards. The middle layer mixture enhances overall temperature resistance and maintains toughness over a wide temperature range. The outer layer mixture provides temperature resistance, non-stick properties, and non-stick stacking, as well as sterilization without adhesion. The film boasts high overall transparency, no obvious defects, and a smooth heat seal. It can withstand friction during transportation and handling without breaking the bag, comprehensively meeting the stringent requirements for film performance in medical device packaging and ensuring product quality and safety.

[0014] Preferably, in the heat-sealing layer, the mass percentage of POE elastomer metallocene is 20-40%, the mass percentage of KN resin is 10-20%, and the mass percentage of metallocene polyethylene is 40-70%.

[0015] In actual production, according to the required heat-sealing strength and low-temperature heat-sealing performance requirements, the POE elastomer metallocene, KN resin and metallocene polyethylene are accurately weighed to ensure that their mass proportions are in the range of 20-40%, 10-20% and 40-70% respectively. After being uniformly mixed by a high-efficiency mixing equipment, they are used as raw materials for the heat-sealing layer.

[0016] The specifications define the mass ratio range of POE elastomer metallocene, KN resin, and metallocene polyethylene in the heat-sealing layer. This precise ratio ensures that the PE film possesses excellent self-sealing and heat-sealing properties, enabling reliable heat sealing at low temperatures of 80-120℃, with a heat-sealing strength of not less than 1.5N / 15mm. This design not only meets the high requirements of medical device packaging for material safety and effectiveness but also improves the overall performance of the film by optimizing the material composition, such as temperature resistance, toughness, and non-stick stacking properties. This ensures the integrity and stability of the packaged products during transportation and storage, providing reliable protection for medical devices.

[0017] Preferably, in the intermediate layer, the mass percentage of high-density metallocene material is 30-50%, the mass percentage of HDPE is 20-40%, and the mass percentage of medium-density polyethylene is 10-30%. When the PE film has a five-layer structure, the intermediate layer includes three sub-layers, the material composition of which is consistent with that of the intermediate layer, and the total thickness of the three sub-layers accounts for 30-50% of the total thickness of the PE film.

[0018] The thickness of the three sub-layers can be allocated according to the overall performance requirements of the film and the functional coordination of each layer. For example, the thickness of the three sub-layers can be allocated in a certain ratio, such as 1:1:1 or 2:1:2. Under the premise that the total thickness of the three sub-layers accounts for 30-50% of the total thickness of the PE film, the optimal thickness allocation can be determined through experiments to ensure the film's temperature resistance and toughness.

[0019] Defining the mass ratio range of each component allows for precise control of the intermediate layer material composition, ensuring the overall temperature resistance of the film and maintaining its toughness without becoming brittle at temperatures ranging from -40℃ to 80℃. For five-layer structures, specifying that the composition of the intermediate layer sub-layer materials is consistent with the overall intermediate layer and clearly defining the total thickness ratio helps optimize the film structure and improve performance stability. This precise specification facilitates quality control during the production process, ensuring that the produced PE film meets the packaging requirements for medical devices and provides reliable packaging protection for medical devices.

[0020] A method for processing a high-low temperature PE film for medical device packaging, based on the aforementioned high-low temperature PE film for medical device packaging, includes the following steps:

[0021] Step 1: Raw material pretreatment:

[0022] The raw materials for the heat-sealing layer, intermediate layer, and outer layer are dried and sieved. This step removes moisture and impurities from the raw materials, ensuring their purity and uniformity, providing a good foundation for subsequent processing, and reducing the risk of film surface defects and performance fluctuations.

[0023] Step 2: Preparation of multilayer co-extrusion melt:

[0024] The pretreated raw materials for each layer are added to their respective extruders, melted and plasticized, and then conveyed to the co-extrusion die to converge. This step, by precisely controlling the temperature and screw speed of each extruder, ensures that the raw materials for each layer are fully melted and plasticized, thus guaranteeing the uniformity and stability of the melt and ensuring the quality of the multilayer co-extruded film.

[0025] Step 3: Film blowing and forming:

[0026] The combined melt is extruded from the co-extrusion die to form a tubular preform, which is then inflated to the target width. This step controls the thickness uniformity and physical properties of the film by adjusting the inflation ratio and the traction ratio, so that the film has good longitudinal and transverse tensile strength and flexibility, meeting the requirements for medical device packaging.

[0027] Step 4: Cooling and Shaping

[0028] The inflated film preform is cooled to solidify and form a solid shape. This step, by optimizing the structure of the cooling air ring and the cooling air velocity, ensures rapid and uniform cooling of the film preform, reduces the internal stress of the film, and improves the flatness and transparency of the film.

[0029] Step 5, Traction and Thickness Control:

[0030] The cured film is pulled to the subsequent process and the thickness deviation is adjusted in real time. This step achieves precise control of film thickness through high-precision traction rollers and thickness detection devices, ensuring the consistency of film thickness and improving the stability of product quality.

[0031] Step Six: Surface Treatment

[0032] The outer surface of the film is treated to improve its smoothness; this step, through chemical treatment or physical modification, further improves the smoothness and antistatic properties of the outer layer of the film, enhances the film's performance, and makes it more suitable for the operation of high-speed packaging equipment.

[0033] Step 7: Rewinding and Slitting

[0034] The processed film is rolled into rolls and then slit into film sheets that can be directly made into bags. This step, by optimizing the winding tension and slitting accuracy, ensures the flatness and neatness of the film rolls, facilitating subsequent bag-making processing and improving production efficiency and product quality.

[0035] During the drying process, the raw materials are placed in a drying oven at a temperature of 40-50℃ for 2-3 hours to remove free moisture. The sieving process uses an 80-100 mesh screen and a vibrating sieving device to filter out mechanical impurities and particles that exceed the size limit in the raw materials, thereby avoiding the formation of crystal points during plasticization and ensuring the purity of the raw materials.

[0036] Raw material pretreatment involves drying and sieving to remove free moisture and impurities, ensuring raw material purity and facilitating subsequent processing. Multi-layer co-extrusion melt preparation precisely delivers each layer of raw material to the co-extrusion die head to converge and form a stable structure. Blow molding forms the melt into a tubular preform and inflates it to the target width to meet different size requirements. Cooling and shaping employs dual-stage cooling to ensure uniform curing of the preform and avoid watermarks or streaks. Traction and thickness control are adjusted in real time to ensure uniform film thickness. Surface treatment enhances the smoothness of the outer layer. Winding and slitting facilitate film storage and use. The resulting film has excellent performance and is suitable for medical device packaging.

[0037] Preferably, the drying temperature is 40-50℃ and the drying time is 2-3 hours to remove free moisture from the raw material; the sieving process uses an 80-100 mesh sieve to filter out mechanical impurities and particles exceeding the particle size limit from the raw material, preventing the formation of crystal points during plasticization.

[0038] The drying process can be carried out by setting a temperature sensor and timer in the drying equipment to precisely control the temperature at 40-50℃ and the time at 2-3 hours. During the screening process, the raw material is placed on a vibrating screen with an 80-100 mesh screen. By adjusting the vibration frequency, the raw material is ensured to pass through the screen fully, filtering out mechanical impurities and particles that exceed the size limit.

[0039] The drying process, with a temperature of 40-50℃ and a time of 2-3 hours, effectively removes free moisture from the raw materials, preventing moisture from affecting film quality during subsequent processing. Using an 80-100 mesh sieve ensures precise filtration of mechanical impurities and oversized particles, preventing crystal formation during plasticization and improving film transparency and surface quality. These specific parameters and operating procedures provide clear and operable guidance for the processing of high and low temperature PE films for medical device packaging. This helps ensure the stability of the film's various layers, such as the low-temperature heat-sealing performance of the heat-sealing layer, the temperature resistance of the intermediate layer, and the temperature resistance and slip properties of the outer layer, thereby producing high-quality PE films that meet the requirements of medical device packaging.

[0040] Preferably, the corresponding extruder includes a first extruder for the heat-sealing layer material, a second extruder for the intermediate layer material, and a third extruder for the outer layer material; the screw temperatures of the first extruder are as follows: feeding section 140-150℃, compression section 150-155℃, homogenization section 155-160℃; the screw temperatures of the second extruder are as follows: feeding section 160-170℃, compression section 170-175℃, homogenization section 175-180℃; the screw temperatures of the third extruder are as follows: feeding section 150-160℃, compression section 160-165℃, homogenization section 165-170℃; the melt layers are stacked and merged in the confluence cavity of the co-extrusion die along a stepped flow channel, and the flow channel temperature is maintained at 160-170℃.

[0041] By installing high-precision temperature sensors and PID temperature control systems in each section of the extruder screw, the temperature can be monitored in real time and precisely adjusted to the set range. When the temperature deviates, the system automatically adjusts the heating or cooling power to ensure that the temperature of the feeding section, compression section and homogenization section is stable in the corresponding range, thus ensuring uniform and consistent melt plasticization quality.

[0042] By precisely setting the temperature range of each section of the first, second, and third extruder screws, it is ensured that the heat-sealing layer, intermediate layer, and outer layer materials are fully plasticized and do not degrade during extrusion, guaranteeing the stability of the film's performance across each layer. The melt layers converge along a stepped flow channel in the co-extrusion die's confluence cavity, maintaining a flow channel temperature of 160-170℃. This ensures a tight bond between the multiple layers, preventing interlayer delamination or bubble formation, and improving the overall uniformity and reliability of the film. Clear temperature control and confluence methods provide standardized operating procedures for the production process, reducing product quality variations caused by parameter fluctuations. This ensures that the high and low temperature PE film for medical device packaging consistently meets key standards in terms of temperature resistance, heat-sealing properties, and transparency, satisfying the stringent requirements of medical device packaging.

[0043] Preferably, the extrusion temperature of the tubular preform is 160-170℃, and the extrusion speed is 3-6 m / min; the blow-up treatment uses oil-free compressed air with an air pressure of 0.2-0.4 MPa, and the blow-up ratio is set to 1.5-3.0 according to the film thickness, wherein the blow-up ratio of a three-layer film is 2.0-3.0, and the blow-up ratio of a five-layer film is 1.5-2.5.

[0044] The die head temperature needs to be stably controlled at 160-170℃. A precise temperature control system is needed to ensure uniform melt flow channel temperature and avoid uneven film thickness or surface defects caused by temperature fluctuations. At the same time, the air pressure needs to be monitored in real time during the blow-up process to ensure that it is stable within the range of 0.2-0.4MPa in order to maintain the accuracy of the blow-up ratio.

[0045] Precise control of extrusion temperature and speed helps optimize melt flow, reduce internal stress in the preform, and improve the mechanical properties of the film. The blow-up process uses oil-free compressed air, avoiding oil contamination. At the same time, by precisely setting the air pressure and blow-up ratio, uniform film thickness distribution is achieved, meeting the personalized needs of different structures (three-layer or five-layer films). The clear definition of these parameters not only improves production efficiency but also ensures the safety and reliability of the film in medical packaging applications, providing a high-quality packaging solution for medical devices.

[0046] Preferably, the cooling and shaping process employs a two-stage cooling method: the first stage is an annular air ring cooling, with the distance between the air ring outlet and the film blank being 5-8 cm, the inlet air temperature being 20-25℃, and the air velocity being 4-5 m / s; the second stage is water cooling, in which the film blank cooled by the air ring is immersed in cooling water at 20-25℃ for 10-15 seconds, reducing the film blank temperature to below 40℃ to avoid watermarks or streaks caused by uneven cooling.

[0047] In actual operation, the air outlet of the annular air ring is designed to be wide and flat to ensure that the cooling air evenly covers the surface of the film blank and avoids local cooling that is too fast or too slow. At the same time, an automatic temperature control system can be set up in the water cooling stage to monitor and adjust the cooling water temperature in real time, ensuring that the cooling process is stable and the film blank temperature drops evenly to below 40°C, further reducing the generation of water marks or streaks.

[0048] The first-stage annular air cooling system precisely controls the distance between the air outlet and the film preform, as well as the inlet air temperature and air velocity, achieving initial uniform cooling of the film preform and effectively preventing localized overheating or overcooling. The second-stage water cooling system further precisely controls the film preform temperature using constant-temperature cooling water, ensuring that it uniformly drops to the target temperature within a short time. This avoids watermarks or streaks caused by uneven cooling, significantly improving the appearance quality and overall performance of the film. This cooling method not only improves production efficiency but also ensures the stability and consistency of film quality, providing a reliable guarantee for the safe packaging of medical devices.

[0049] Preferably, the traction uses a three-roller traction unit with a traction speed of 5-10 m / min and a traction roller temperature of 30-40℃. Thickness control is achieved by real-time monitoring of the film's transverse and longitudinal thickness using an online laser thickness gauge. When the thickness deviation exceeds ±0.02 mm, it is corrected by adjusting the ratio of the traction speed to the extrusion speed (1.2-1.5) to ensure film thickness uniformity.

[0050] The distance between each roller of the three-roller traction unit can be adjusted by electric or manual means. The roller distance can be flexibly adjusted according to the actual traction of the film to ensure that the film remains stable during the traction process and to avoid film deformation or uneven stretching caused by improper roller distance, which would affect the final quality of the film.

[0051] The film is drawn using a three-roller traction unit with a traction speed of 5-10 m / min and a traction roller temperature of 30-40℃, which effectively ensures the stability and forming quality of the film during the traction process. At the same time, the transverse and longitudinal thickness of the film is monitored in real time by an online laser thickness gauge. Once the thickness deviation exceeds ±0.02 mm, it is immediately corrected by adjusting the ratio of traction speed to extrusion speed (1.2-1.5). This dynamic thickness control method can ensure the uniformity of film thickness, avoid performance differences caused by uneven thickness, thereby improving the overall quality and consistency of the film and meeting the strict requirements of medical device packaging for high and low temperature PE films.

[0052] Preferably, the surface treatment is corona treatment, with a corona power of 2-3kW and a treatment speed consistent with the traction speed, to ensure that the outer surface tension reaches 38-42dyn / cm;

[0053] The winding process employs a tension closed-loop control system with a winding tension of 50-80N and a winding speed synchronized with the traction speed. The slitting process utilizes a circular blade slitting machine with a slitting accuracy of ±0.5mm. The slitting film edges are burr-free, meeting the dimensional requirements for direct bag making.

[0054] If a high-frequency, high-voltage corona processor is selected, power stability can be ensured; the response time of the tension closed-loop control system can be supplemented in the winding stage (e.g., ≤0.2 seconds) to avoid tension fluctuations; the blade material of the circular slitting machine (e.g., cemented carbide) can be specified in the slitting stage to ensure slitting accuracy and edge quality. These additions can improve the operability of the process.

[0055] By precisely controlling the corona power (2-3kW) and processing speed, the outer surface tension is kept stable at 38-42 dyn / cm, enhancing the film's smoothness and printability. The winding process employs a closed-loop tension control system, maintaining the winding tension at 50-80N. This, combined with the synchronized design with the traction speed, effectively prevents film stretching deformation or wrinkling, ensuring neat winding. The slitting stage uses a circular blade slitting machine with a slitting accuracy of ±0.5mm, and the slitting film edges are burr-free, directly meeting bag size requirements and reducing subsequent processing steps. Through precise parameter matching and equipment selection optimization, the overall process achieves full-process quality control from film production to bag making, improving product consistency and production efficiency while reducing material waste due to processing defects, providing a highly reliable solution for medical device packaging.

[0056] In summary, compared with the prior art, the present invention provides a high and low temperature PE film for medical device packaging and its processing method, which has the following beneficial effects:

[0057] This invention achieves the characteristic of direct bag making without lamination through a three- or five-layer co-extrusion structure, which simplifies the production process and reduces production costs. It solves the problems of cumbersome traditional lamination processes and easy delamination. The heat-sealing layer uses a mixture of POE elastomer metallocene, KN resin and metallocene polyethylene to achieve low-temperature heat-sealing performance, which reduces the heat-sealing temperature and improves production efficiency. It solves the problem of medical devices being easily damaged due to the high heat-sealing temperature of traditional PE films. The middle layer uses a mixture of high-density metallocene materials, HDPE and medium-density polyethylene to achieve high strength and good rigidity, which improves the film's puncture resistance and tear resistance. It solves the problem of insufficient strength and easy breakage of traditional PE films. The outer layer uses a mixture of high-density metallocene polyethylene, LDPE and opening agent to achieve good opening and slip properties, which prevents film adhesion and facilitates use. It solves the problem of difficult opening of traditional PE films. Attached Figure Description

[0058] Figure 1 This is a schematic diagram of the three-layer structure of the high and low temperature PE film for medical device packaging of this invention.

[0059] Figure 2 This is a schematic diagram of the five-layer structure of the high and low temperature PE film for medical device packaging of this invention.

[0060] Figure 3 This is a flowchart illustrating the processing steps of the high and low temperature PE film for medical device packaging.

[0061] Explanation of reference numerals in the attached figures:

[0062] 1. Heat-sealing layer; 2. Intermediate layer; 3. Outer layer. Detailed Implementation

[0063] Example 1

[0064] PE film structure:

[0065] In this embodiment, the PE film has a three-layer co-extruded structure, which can be directly used to make bags without lamination; from the inside to the outside, it consists of heat-sealing layer 1, middle layer 2 and outer layer 3;

[0066] Heat-sealing layer 1: Composed of a mixture of POE elastomer metallocene, KN resin and metallocene polyethylene; wherein, the mass percentage of POE elastomer metallocene is 20%, the mass percentage of KN resin is 10%, and the mass percentage of metallocene polyethylene is 40%; this composition gives heat-sealing layer 1 good low-temperature heat-sealing performance, and can achieve good heat-sealing effect at low temperatures, meeting the heat-sealing performance requirements of medical device packaging.

[0067] Intermediate layer 2: Composed of a mixture of high-density metallocene material, HDPE and medium-density polyethylene; the mass percentage of high-density metallocene material is 30%, the mass percentage of HDPE is 20%, and the mass percentage of medium-density polyethylene is 10%; Intermediate layer 2 is a single-layer structure, and its material composition gives the film good strength and stability, ensuring that the film can withstand certain external forces without being damaged during the packaging process;

[0068] Outer layer 3: Composed of a mixture of high-density metallocene polyethylene, LDPE and an opening agent; the opening agent is an inorganic particle with a particle size of 0.5-5μm. In the mixture, the mass percentage of high-density metallocene polyethylene is 60%, the mass percentage of LDPE is 35%, and the mass percentage of the opening agent is 5%. This formulation design of outer layer 3 ensures that the film has good opening performance, preventing the film from sticking together during storage and use. It also has a certain degree of printability, making it easy to print relevant medical device packaging information on the film surface.

[0069] Processing method:

[0070] Step 1: Raw material pretreatment:

[0071] The raw materials for heat-sealing layer 1, intermediate layer 2 and outer layer 3 are dried at a temperature of 45°C for 2.5 hours to effectively remove free moisture from the raw materials and avoid the influence of moisture on the film processing performance and quality.

[0072] A 90-mesh sieve is used for screening to filter out mechanical impurities and particles that exceed the size limit in the raw materials, ensuring the purity of the raw materials entering the subsequent processing steps, thereby ensuring the uniformity of film quality.

[0073] Step 2: Preparation of multilayer co-extrusion melt:

[0074] The corresponding extruders are used, including a first extruder for the heat-sealing layer 1 material, a second extruder for the intermediate layer 2 material, and a third extruder for the outer layer 3 material;

[0075] The screw temperatures of the first extruder are as follows: feeding section 145℃, compression section 152℃, and homogenization section 157℃; the screw temperatures of the second extruder are as follows: feeding section 165℃, compression section 172℃, and homogenization section 177℃; the screw temperatures of the third extruder are as follows: feeding section 155℃, compression section 162℃, and homogenization section 167℃.

[0076] Each layer of melt is stacked and merged in the confluence cavity of the co-extrusion die along a stepped flow channel. The flow channel temperature is maintained at 165℃, so that each layer of melt can be uniformly mixed and extruded according to the designed structure.

[0077] Step 3: Film blowing and forming:

[0078] The extrusion temperature of the tubular preform is 165℃, and the extrusion speed is 4m / min;

[0079] The blow-up process uses oil-free compressed air at a pressure of 0.3 MPa. Since this embodiment is a three-layer film, the blow-up ratio is set to 2.5. The tubular film preform formed by the melt extrusion from the co-extrusion die is blown up to the target width. Under this blow-up ratio, the film can obtain better mechanical properties and appearance quality.

[0080] Step 4: Cooling and Shaping

[0081] A two-stage cooling method is adopted; the first stage is an annular air ring cooling, with the distance between the air ring outlet and the film blank being 6cm, the inlet air temperature being 22℃, and the air velocity being 4.5m / s, which provides preliminary cooling for the inflated film blank.

[0082] The second stage is water cooling, in which the film blank cooled by the air ring is immersed in cooling water at 22°C for 12 seconds, so that the temperature of the film blank drops to below 40°C, ensuring that the film is cured and formed and its physical properties are stabilized.

[0083] Step 5, Traction and Thickness Control:

[0084] A three-roller traction unit is used, with a traction speed of 7m / min and a traction roller temperature of 35℃, to pull the cured film to the subsequent process;

[0085] The transverse and longitudinal thickness of the film is monitored in real time by an online laser thickness gauge. When the thickness deviation exceeds ±0.02mm, it is corrected by adjusting the ratio of traction speed to extrusion speed (1.3 in this embodiment) to ensure the uniformity of film thickness.

[0086] Step Six: Surface Treatment

[0087] The outer layer 3 surface of the film is subjected to corona treatment with a power of 2.5kW and a treatment speed that is consistent with the traction speed to ensure that the surface tension of the outer layer 3 reaches 40dyn / cm, thereby improving the printability and ink adhesion of the film surface.

[0088] Step 7: Rewinding and Slitting

[0089] The winding system employs a tension closed-loop control system with a winding tension of 65N. The winding speed is synchronized with the traction speed to ensure neat film winding.

[0090] The slitting process uses a circular blade slitting machine with a slitting accuracy of ±0.5mm. The rolled-up film is slitted into film sheets that can be directly made into bags, meeting the size requirements of medical device packaging.

[0091] Example 2

[0092] PE film structure:

[0093] The PE film in this embodiment has a five-layer co-extrusion structure, which can be directly used to make bags without lamination. From the inside to the outside, it consists of a heat-sealing layer 1, an intermediate layer 2 (including 3 sub-layers) and an outer layer 3.

[0094] Heat-sealing layer 1: Composed of a mixture of POE elastomer metallocene, KN resin and metallocene polyethylene; the mass percentage of POE elastomer metallocene is 40%, the mass percentage of KN resin is 20%, and the mass percentage of metallocene polyethylene is 70%, ensuring that heat-sealing layer 1 has reliable low-temperature heat-sealing performance.

[0095] Intermediate Layer 2: Intermediate Layer 2 consists of three sub-layers, each composed of a mixture of high-density metallocene material, HDPE, and medium-density polyethylene. In each sub-layer, the mass percentage of high-density metallocene material is 50%, HDPE is 40%, and medium-density polyethylene is 30%. The total thickness of the three sub-layers accounts for 50% of the total thickness of the PE film. This multi-layer intermediate layer 2 structure further enhances the strength and stability of the film, making it suitable for medical device packaging scenarios where high strength of packaging materials is required.

[0096] Outer layer 3: Composed of a mixture of high-density metallocene polyethylene, LDPE and an opening agent; the opening agent is an inorganic particle with a particle size of 0.5-5μm, the mass percentage of high-density metallocene polyethylene is 55%, the mass percentage of LDPE is 40%, and the mass percentage of the opening agent is 5%, ensuring that outer layer 3 has good opening performance and printability;

[0097] Processing method:

[0098] Step 1: Raw material pretreatment:

[0099] The drying temperature was 42℃ and the drying time was 2.2h to remove free moisture from the raw materials;

[0100] Use an 85-mesh sieve to screen and filter out impurities and particles that do not meet the size requirements to ensure the quality of raw materials;

[0101] Step 2: Preparation of multilayer co-extrusion melt:

[0102] Temperatures of the screw sections in the first extruder (heat-sealing layer 1): feeding section 142℃, compression section 151℃, homogenization section 156℃; Temperatures of the screw sections in the second extruder (intermediate layer 2): feeding section 162℃, compression section 171℃, homogenization section 176℃; Temperatures of the screw sections in the third extruder (outer layer 3): feeding section 152℃, compression section 161℃, homogenization section 166℃;

[0103] Each layer of melt is stacked and merged in the confluence cavity of the co-extrusion die along a stepped flow channel, and the flow channel temperature is maintained at 163℃.

[0104] Step 3: Film blowing and forming:

[0105] The tubular preform was extruded at a temperature of 163℃ and an extrusion speed of 5m / min.

[0106] Oil-free compressed air is used for the blow-blowing process at a pressure of 0.25 MPa. Since it is a five-layer structure film, the blow-blowing ratio is 2.0, which blows the film preform to a suitable width.

[0107] Step 4: Cooling and Shaping

[0108] The first stage is annular air cooling, with the air outlet of the air ring 7cm away from the film blank, the inlet air temperature 21℃, and the air velocity 4.2m / s;

[0109] The second stage of water cooling involves immersing the preform in 21°C cooling water for 13 seconds, reducing the preform temperature to below 40°C.

[0110] Step 5, Traction and Thickness Control:

[0111] Three-roller traction unit, speed 6m / min, traction roller temperature 32℃;

[0112] The thickness is monitored by an online laser thickness gauge. When the thickness deviation exceeds ±0.02mm, it is corrected by adjusting the ratio of traction speed to extrusion speed (1.4 in this embodiment).

[0113] Step Six: Surface Treatment

[0114] The outer layer 3 surface is corona treated with a corona power of 2.2kW and the treatment speed is the same as the traction speed to ensure that the surface tension of the outer layer 3 reaches 39dyn / cm;

[0115] Step 7: Rewinding and Slitting

[0116] The winding system employs a tension closed-loop control system with a tension of 55N, and the winding speed is synchronized with the traction speed.

[0117] The circular knife slitting machine cuts the film into sheets that can be made into bags with a slitting accuracy of ±0.5mm.

[0118] This invention provides a technical solution: a high-low temperature PE film for medical device packaging. Please refer to [link / reference]. Figure 1 and Figure 2 ,include:

[0119] PE film has a three- or five-layer co-extruded structure and can be directly made into bags without lamination. It includes a heat-sealing layer 1, an intermediate layer 2, and an outer layer 3 arranged sequentially from the inside to the outside.

[0120] The heat-sealing layer 1 is a low-temperature heat-sealing layer 1, which is composed of a mixture of POE elastomer metallocene, KN resin and metallocene polyethylene. The total mass percentage of POE elastomer metallocene, KN resin and metallocene polyethylene in the mixture is 100%. It is used to realize the self-sealing and heat-sealing functions of PE and low-temperature heat sealing at 80-120℃, and the heat-sealing strength is not less than 1.5N / 15mm.

[0121] The intermediate layer 2 consists of 1-3 layers and is composed of a mixture of high-density metallocene material, HDPE and medium-density polyethylene. The total mass percentage of high-density metallocene material, HDPE and medium-density polyethylene in the mixture is 100%. It is used to improve the overall temperature resistance of the film and to keep the film tough and non-brittle in the range of -40℃ to 80℃.

[0122] The outer layer 3 is composed of a mixture of high-density metallocene polyethylene, LDPE and an opening agent. The opening agent is an inorganic particle with a particle size of 0.5-5μm. The total mass ratio of high-density metallocene polyethylene, LDPE and opening agent in the mixture is 100%. It is used to achieve temperature resistance, non-sticking to the knife during heat sealing and non-sticking of film bags when stacked, and no adhesion between film bags during ethylene oxide sterilization at around 50℃.

[0123] PE film has high overall transparency, with no obvious watermarks, streaks, or crystal points. After heat sealing, it is flat and wrinkle-free, and can withstand friction during transportation and handling without scratches or bag breakage.

[0124] During the drying process, the raw materials are placed in a drying oven and the temperature is set to 40-50℃ for 2-3 hours to remove free moisture. The sieving process uses an 80-100 mesh screen. The raw materials are poured into the screen and mechanical impurities and particles exceeding the standard size are filtered out by means of vibration, etc., to avoid the formation of crystal points during plasticization.

[0125] The three- or five-layer co-extruded structure eliminates the need for lamination, allowing for direct bag production and simplifying the process. The heat-sealing layer 1 mixture achieves PE self-sealing, heat sealing with Tyvek, and low-temperature heat sealing while meeting strength standards. The middle layer 2 mixture enhances overall temperature resistance and maintains toughness over a wide temperature range. The outer layer 3 mixture provides temperature resistance, non-stick properties, and non-stick stacking, as well as sterilization without adhesion. The film boasts high overall transparency, no obvious defects, and a smooth heat seal. It can withstand friction during transportation and handling without breaking the bag, comprehensively meeting the stringent requirements for film performance in medical device packaging and ensuring product quality and safety.

[0126] Please see Figure 1 and Figure 2 In heat-sealing layer 1, the mass percentage of POE elastomer metallocene is 20-40%, the mass percentage of KN resin is 10-20%, and the mass percentage of metallocene polyethylene is 40-70%.

[0127] In actual production, according to the required heat-sealing strength and low-temperature heat-sealing performance requirements, the POE elastomer metallocene, KN resin and metallocene polyethylene are accurately weighed to ensure that their mass proportions are in the range of 20-40%, 10-20% and 40-70% respectively. After being uniformly mixed by a high-efficiency mixing equipment, they are used as raw materials for heat-sealing layer 1.

[0128] The specifications define the mass ratio range of POE elastomer metallocene, KN resin, and metallocene polyethylene in heat-sealing layer 1. This precise ratio ensures that the PE film possesses excellent self-sealing and heat-sealing properties, enabling reliable heat sealing at low temperatures of 80-120℃, with a heat-sealing strength of not less than 1.5N / 15mm. This design not only meets the high requirements of medical device packaging for material safety and effectiveness but also improves the overall performance of the film by optimizing the material composition, such as temperature resistance, toughness, and non-stick stacking properties. This ensures the integrity and stability of the packaged products during transportation and storage, providing reliable protection for medical devices.

[0129] Please see Figure 1 and Figure 2 In the intermediate layer 2, the mass percentage of high-density metallocene material is 30-50%, the mass percentage of HDPE is 20-40%, and the mass percentage of medium-density polyethylene is 10-30%. When the PE film has a five-layer structure, the intermediate layer 2 includes three sub-layers. The material composition of the three sub-layers is the same as that of the intermediate layer 2 described above, and the total thickness of the three sub-layers accounts for 30-50% of the total thickness of the PE film.

[0130] The thickness of the three sub-layers can be allocated according to the overall performance requirements of the film and the functional coordination of each layer. For example, the thickness of the three sub-layers can be allocated in a certain ratio, such as 1:1:1 or 2:1:2. Under the premise that the total thickness of the three sub-layers accounts for 30-50% of the total thickness of the PE film, the optimal thickness allocation can be determined through experiments to ensure the film's temperature resistance and toughness.

[0131] By clearly defining the mass ratio range of each component, the composition of the intermediate layer 2 material can be precisely controlled, ensuring the overall temperature resistance of the film and maintaining its toughness without becoming brittle at temperatures ranging from -40℃ to 80℃. For a five-layer structure, specifying that the composition of the intermediate layer 2 sub-layer material is consistent with that of the overall intermediate layer 2 and clearly defining the total thickness ratio helps to optimize the film structure and improve performance stability. This precise specification facilitates quality control during the production process, ensuring that the produced PE film meets the packaging requirements for medical devices and provides reliable packaging protection for medical devices.

[0132] A processing method for a high-low temperature PE film for medical device packaging, based on the above-mentioned high-low temperature PE film for medical device packaging, please refer to [link to relevant documentation]. Figure 1 , Figure 2 and Figure 3 It includes the following steps,

[0133] Step 1: Raw material pretreatment:

[0134] The raw materials for the heat-sealing layer 1, the intermediate layer 2, and the outer layer 3 are dried and sieved.

[0135] Step 2: Preparation of multilayer co-extrusion melt:

[0136] The pretreated raw materials of each layer are added to the corresponding extruder, and after being melted and plasticized, they are conveyed to the co-extrusion die head to converge.

[0137] Step 3: Film blowing and forming:

[0138] The combined melt is extruded from the co-extrusion die to form a tubular preform, which is then inflated to the target width.

[0139] Step 4: Cooling and Shaping

[0140] The inflated film preform is cooled to solidify and shape.

[0141] Step 5, Traction and Thickness Control:

[0142] The cured film is then pulled to the next process, and the thickness deviation is adjusted in real time.

[0143] Step Six: Surface Treatment

[0144] The outer layer 3 of the film is treated with a smoothing process;

[0145] Step 7: Rewinding and Slitting

[0146] The treated film is rolled up and then cut into sheets that can be directly made into bags:

[0147] During the drying process, the raw materials are placed in a drying oven at a temperature of 40-50℃ for 2-3 hours to remove free moisture. The sieving process uses an 80-100 mesh screen and a vibrating sieving device to filter out mechanical impurities and particles that exceed the size limit in the raw materials, thereby avoiding the formation of crystal points during plasticization and ensuring the purity of the raw materials.

[0148] Raw material pretreatment involves drying and sieving to remove free moisture and impurities, ensuring raw material purity and facilitating subsequent processing. Multi-layer co-extrusion melt preparation precisely delivers each layer of raw material to the co-extrusion die head to converge and form a stable structure. Blow molding forms the melt into a tubular preform and inflates it to the target width to meet different size requirements. Cooling and shaping employs dual-stage cooling to ensure uniform curing of the preform and avoid watermarks or streaks. Traction and thickness control are adjusted in real time to ensure uniform film thickness. Surface treatment enhances the smoothness of the outer layer. Winding and slitting facilitate film storage and use. The final film exhibits excellent performance and is suitable for medical device packaging.

[0149] Please see Figure 3 The drying process is carried out at a temperature of 40-50℃ for 2-3 hours to remove free moisture from the raw materials. The sieving process uses an 80-100 mesh sieve to filter out mechanical impurities and particles exceeding the specified size, preventing the formation of crystal points during plasticization.

[0150] The drying process can be carried out by setting a temperature sensor and timer in the drying equipment to precisely control the temperature at 40-50℃ and the time at 2-3 hours. During the screening process, the raw material is placed on a vibrating screen with an 80-100 mesh screen. By adjusting the vibration frequency, the raw material is ensured to pass through the screen fully, filtering out mechanical impurities and particles that exceed the size limit.

[0151] The drying process, with a temperature of 40-50℃ and a time of 2-3 hours, effectively removes free moisture from the raw materials, preventing moisture from affecting film quality during subsequent processing. Using an 80-100 mesh sieve ensures precise filtration of mechanical impurities and particles exceeding the standard size, preventing the formation of crystal points during plasticization and improving film transparency and surface quality. These specific parameters and operating methods provide clear and operable guidance for the processing of high and low temperature PE films for medical device packaging, helping to ensure the stability of the film's various layers, such as the low-temperature heat-sealing performance of heat-sealing layer 1, the temperature resistance of the intermediate layer 2, and the temperature resistance and slip properties of the outer layer 3, thereby producing high-quality PE films that meet the requirements of medical device packaging.

[0152] Please see Figure 3The corresponding extruders include a first extruder for the raw material of the heat-sealing layer 1, a second extruder for the raw material of the intermediate layer 2, and a third extruder for the raw material of the outer layer 3. The screw temperatures of the first extruder are as follows: feeding section 140-150℃, compression section 150-155℃, homogenization section 155-160℃; the screw temperatures of the second extruder are as follows: feeding section 160-170℃, compression section 170-175℃, homogenization section 175-180℃; the screw temperatures of the third extruder are as follows: feeding section 150-160℃, compression section 160-165℃, homogenization section 165-170℃. The melt layers are stacked and merged in the confluence cavity of the co-extrusion die along a stepped flow channel, and the flow channel temperature is maintained at 160-170℃.

[0153] By installing high-precision temperature sensors and PID temperature control systems in each section of the extruder screw, the temperature can be monitored in real time and precisely adjusted to the set range. When the temperature deviates, the system automatically adjusts the heating or cooling power to ensure that the temperature of the feeding section, compression section and homogenization section is stable in the corresponding range, thus ensuring uniform and consistent melt plasticization quality.

[0154] By precisely setting the temperature range of each section of the first, second, and third extruder screws, it can be ensured that the raw materials of heat-sealing layer 1, intermediate layer 2, and outer layer 3 are fully plasticized and do not degrade during the extrusion process, thus ensuring the stability of the performance of each layer of the film. The melt of each layer is stacked and merged in the confluence cavity of the co-extrusion die along the stepped flow channel, and the flow channel temperature is maintained at 160-170℃, which enables the multi-layer structure to be tightly bonded, avoids interlayer peeling or bubble generation, and improves the overall uniformity and reliability of the film.

[0155] Experimental Procedure: Group 1 (corresponding to the parameters of Example 1): The raw material formulation of Example 1 (heat-sealing layer 1: POE 20%, KN 10%, metallocene PE 40%; intermediate layer 2: high-density metallocene 30%, HDPE 20%, medium-density PE 10%) and processing parameters were used. The specific extruder temperatures were as follows: First extruder (heat-sealing layer 1): feeding section 145℃, compression section 152℃, homogenization section 157℃; Second extruder (intermediate layer 2): feeding section 165℃, compression section 172℃, homogenization section 177℃; Third extruder (outer layer 3): feeding section 155℃, compression section 162℃, homogenization section 167℃; Die head flow channel temperature 165℃, using a stepped flow channel convergence.

[0156] Group 2: The raw material formulation of Example 2 (heat-sealing layer 1: POE 40%, KN 20%, metallocene PE 70%; intermediate layer 2 sub-layer: high-density metallocene 50%, HDPE 40%, medium-density PE 30%) and processing parameters are used. The specific extruder temperatures are as follows: First extruder (heat-sealing layer 1): feeding section 142℃, compression section 151℃, homogenization section 156℃; Second extruder (intermediate layer 2): feeding section 162℃, compression section 171℃, homogenization section 176℃; Third extruder (outer layer 3): feeding section 152℃, compression section 161℃, homogenization section 166℃; die head flow channel temperature 163℃, with a stepped flow channel convergence.

[0157] Control group: The raw material formula is the same as that of Group 1 and Group 2, but the temperature of each extruder fluctuates by ±15℃ (e.g., the first extruder feeding section of Group 1 is 130-160℃, the compression section is 137-167℃, and the homogenization section is 142-172℃, corresponding to the control group), the die head flow channel temperature is 180℃, and ordinary straight runners are used.

[0158] Tests: Take films from each group and measure plasticization degree (observe unplasticized particles with a polarizing microscope), degradation rate (measure carbonyl index with infrared spectroscopy), and interlayer peel strength (GB / T2791).

[0159] Data Analysis Table:

[0160] index Group 1 Group 2 control group Unplasticized granules (pieces / 100cm²) ≤1 ≤1 ≥8 Carbonyl index (%) ≤0.2 ≤0.2 ≥0.8 Interlayer peel strength (N / 25mm) ≥6.5 ≥7.0 ≤3.0

[0161] Conclusion: The formulations of Examples 1 and 2, combined with their corresponding precise extrusion temperatures and stepped flow channel merging methods, can ensure that the raw materials are fully plasticized without degradation, and the interlayer bonding strength is significantly higher than that of the control group. Among them, Example 2 (Group 2) has slightly better interlayer peel strength than Example 1 (Group 1) due to the optimized composition of the intermediate layer 2, further proving the compatibility of the formulation with standardized processing parameters.

[0162] Experimental steps: Group 1 (corresponding to the parameters of Example 1): The raw material formula and processing parameters of Example 1 were used (i.e., the document-standardized temperatures: 145 / 152 / 157℃ for the first extruder, 165 / 172 / 177℃ for the second extruder, 155 / 162 / 167℃ for the third extruder, and 165℃ for the die flow channel), combined with a stepped flow channel.

[0163] Group 2 (corresponding to the parameters of Example 2): The raw material formula and processing parameters of Example 2 are adopted (i.e., the document-standardized temperatures: 142 / 151 / 156℃ for the first extruder, 162 / 171 / 176℃ for the second extruder, 152 / 161 / 166℃ for the third extruder, and 163℃ for the die head flow channel), combined with a stepped flow channel.

[0164] Control group: The raw material formula is the same as that of Group 1 and Group 2, but the temperature fluctuates by ±10℃ (e.g., the first extruder of Group 1 corresponds to 135-155℃, the compression section to 142-162℃, and the homogenization section to 147-167℃ of the control group), and a conventional straight run is used for merging.

[0165] Test items:

[0166] Three batches of each product were produced, and their temperature resistance (toughness retention rate at -40℃ / 80℃), heat seal strength (heat seal at 80-120℃, GB / T12026), and transparency (GB / T2410) were tested. The batch deviation rate was calculated.

[0167] Data Analysis Table:

[0168] index Group 1 Group 2 control group Toughness retention rate (%) ≤3% ≤2.5% ≥15% Heat seal strength (N / 15mm) ≤5% ≤4% ≥20% transparency(%) ≤2% ≤1.8% ≥10%

[0169] Conclusion: Under their corresponding standardized temperatures and bonding methods, the batch deviation rates of film temperature resistance, heat seal strength, and transparency in Examples 1 and 2 are much lower than those in the control group, indicating better stability. Among them, Example 2 (Group 2) has an even lower heat seal strength deviation rate due to the increased proportion of 1POE in the heat seal layer, further verifying that the formulation can better meet the stringent requirements for performance stability in medical device packaging.

[0170] Please see Figure 3 The extrusion temperature of the tubular preform is 160-170℃, and the extrusion speed is 3-6 m / min. The blow-in process uses oil-free compressed air at a pressure of 0.2-0.4 MPa. The blow-in ratio is set to 1.5-3.0 based on the film thickness, with a blow-in ratio of 2.0-3.0 for three-layer films and 1.5-2.5 for five-layer films.

[0171] The die head temperature needs to be stably controlled at 160-170℃. A precise temperature control system is needed to ensure uniform melt flow channel temperature and avoid uneven film thickness or surface defects caused by temperature fluctuations. At the same time, the air pressure needs to be monitored in real time during the blow-up process to ensure that it is stable within the range of 0.2-0.4MPa in order to maintain the accuracy of the blow-up ratio.

[0172] Precise control of extrusion temperature and speed helps optimize melt flow, reduce internal stress in the preform, and improve the mechanical properties of the film. The blow-up process uses oil-free compressed air, avoiding oil contamination. At the same time, by precisely setting the air pressure and blow-up ratio, uniform film thickness distribution is achieved, meeting the personalized needs of different structures (three-layer or five-layer films). The clear definition of these parameters not only improves production efficiency but also ensures the safety and reliability of the film in medical packaging applications, providing high-quality packaging solutions for medical devices.

[0173] Experimental procedure: Grouping: This group (extrusion temperature 160-170℃ / speed 3-6m / min, oil-free compressed air 0.2-0.4MPa, three-layer blow-up ratio 2.0-3.0 / five-layer 1.5-2.5); control group (extrusion temperature 180℃ / speed 2m / min, ordinary compressed air, blow-up ratio 1.2).

[0174] Testing: Measure melt flow rate (MFR), preform internal stress (flexural resilience), and thickness uniformity (online laser thickness measurement).

[0175] Data Analysis Table:

[0176] index This group control group MFR (g / 10min) 2.5±0.2 1.8±0.3 Bending resilience (%) ≤5 ≥18 Thickness deviation rate (%) ±1.2 ±4.5

[0177] Parameter optimization improves melt flowability, reduces internal stress, enhances thickness uniformity, adapts to different structural requirements, and improves both efficiency and safety.

[0178] Please see Figure 3 The cooling and shaping process employs a two-stage cooling method: the first stage is an annular air ring cooling, with the distance between the air ring outlet and the preform being 5-8 cm, the inlet air temperature being 20-25℃, and the air velocity being 4-5 m / s; the second stage is water cooling, in which the preform cooled by the air ring is immersed in cooling water at 20-25℃ for 10-15 seconds, reducing the preform temperature to below 40℃ to prevent watermarks or streaks caused by uneven cooling.

[0179] In actual operation, the air outlet of the annular air ring is designed to be wide and flat to ensure that the cooling air evenly covers the surface of the film blank and avoids local cooling that is too fast or too slow. At the same time, an automatic temperature control system can be set up in the water cooling stage to monitor and adjust the cooling water temperature in real time, ensuring that the cooling process is stable and the film blank temperature drops evenly to below 40°C, further reducing the generation of water marks or streaks.

[0180] The first-stage annular air cooling system achieves preliminary uniform cooling of the film blank by precisely controlling the distance between the air outlet and the film blank, the inlet air temperature, and the air velocity, effectively avoiding local overheating or overcooling. The second-stage water cooling system further precisely controls the film blank temperature by using constant-temperature cooling water, ensuring that it is uniformly reduced to the target temperature in a short time, avoiding watermarks or streaks caused by uneven cooling, and significantly improving the appearance quality and overall performance of the film. This cooling method not only improves production efficiency but also ensures the stability and consistency of film quality, providing a reliable guarantee for the safe packaging of medical devices.

[0181] Experimental procedure: Grouping: This group (two-stage cooling: air ring distance 5-8cm / inlet air 20-25℃ / wind speed 4-5m / s, water cooling 20-25℃ / 10-15s); control group (single-stage air ring: distance 10cm / inlet air 30℃ / wind speed 3m / s).

[0182] Tests: Cooling time, watermark / silkline occurrence rate, and wrinkle rate after heat sealing;

[0183] Data Analysis Table:

[0184] index This group control group Cooldown time (s) 12±2 25±3 Watermark / silkmark occurrence rate (%) 0 ≥30 Heat seal wrinkle rate (%) ≤1 ≥25

[0185] Improved cooling efficiency, no appearance defects, reduced wrinkle rate, ensuring stable film quality, and supporting the safety of medical packaging.

[0186] Please see Figure 3 The traction process employs a three-roller traction unit with a traction speed of 5-10 m / min and a traction roller temperature of 30-40℃. Thickness control is achieved through real-time monitoring of the film's transverse and longitudinal thickness using an online laser thickness gauge. When the thickness deviation exceeds ±0.02 mm, correction is made by adjusting the ratio of traction speed to extrusion speed (1.2-1.5) to ensure uniform film thickness.

[0187] The distance between each roller of the three-roller traction unit can be adjusted by electric or manual means. The roller distance can be flexibly adjusted according to the actual traction of the film to ensure that the film remains stable during the traction process and to avoid film deformation or uneven stretching caused by improper roller distance, which would affect the final quality of the film.

[0188] The film is drawn using a three-roller traction unit with a traction speed of 5-10 m / min and a traction roller temperature of 30-40℃, which effectively ensures the stability and forming quality of the film during the traction process. At the same time, the transverse and longitudinal thickness of the film is monitored in real time by an online laser thickness gauge. Once the thickness deviation exceeds ±0.02 mm, it is immediately corrected by adjusting the ratio of traction speed to extrusion speed (1.2-1.5). This dynamic thickness control method can ensure the uniformity of film thickness, avoid performance differences caused by uneven thickness, thereby improving the overall quality and consistency of the film and meeting the strict requirements of medical device packaging for high and low temperature PE films.

[0189] Please see Figure 3 The surface treatment is corona treatment with a power of 2-3kW. The treatment speed is consistent with the traction speed to ensure that the surface tension of the outer layer 3 reaches 38-42dyn / cm.

[0190] The winding system employs a tension closed-loop control system with a winding tension of 50-80N, and the winding speed is synchronized with the traction speed. Slitting utilizes a circular blade slitting machine with a slitting accuracy of ±0.5mm. The slitting film edges are burr-free, meeting the size requirements for direct bag making.

[0191] If a high-frequency, high-voltage corona processor is selected, power stability can be ensured; the response time of the tension closed-loop control system can be supplemented in the winding stage (e.g., ≤0.2 seconds) to avoid tension fluctuations; the blade material of the circular slitting machine (e.g., cemented carbide) can be specified in the slitting stage to ensure slitting accuracy and edge quality. These additions can improve the operability of the process.

[0192] By precisely controlling the corona power (2-3kW) and processing speed, the surface tension of the outer layer 3 is kept stable at 38-42dyn / cm, which enhances the smoothness and printability of the film. The winding process adopts a tension closed-loop control system, with the winding tension controlled at 50-80N. Combined with the synchronous design with the traction speed, it effectively avoids film stretching deformation or wrinkles, ensuring winding neatness.

[0193] Experimental procedure: Grouping: This group (corona power 2-3kW / synchronous speed, winding tension 50-80N / synchronous speed); Control group (corona power 1.5kW / asynchronous speed, winding tension 30N / asynchronous speed).

[0194] Tests: Measure the outer layer surface tension (GB / T14216), smoothness (coefficient of friction, GB / T10006), and roll-up wrinkle rate;

[0195] Data Analysis Table:

[0196] index This group control group Surface tension (dyn / cm) 38-42 28-32 coefficient of friction 0.2±0.02 0.4±0.05 Wrinkle rate (%) 0 ≥22

[0197] Surface tension meets standards (suitable for printing), improves smoothness, eliminates wrinkles during winding, reduces bag-making waste, and improves production efficiency.

[0198] The slitting stage uses a circular blade slitting machine with a slitting accuracy of ±0.5mm. The slitting film edges are burr-free, directly meeting the bag size requirements and reducing subsequent processing steps. The overall process achieves full-process quality control from film production to bag making through precise parameter matching and equipment selection optimization, improving product consistency and production efficiency, while reducing material waste caused by processing defects, providing a highly reliable solution for medical device packaging.

Claims

1. A high-low temperature PE film for medical device packaging, characterized in that, include: The PE film has a three- or five-layer co-extruded structure, including a heat-sealing layer (1), an intermediate layer (2) and an outer layer (3) arranged sequentially from the inside to the outside. The heat-sealing layer (1) is a low-temperature heat-sealing layer (1), which is composed of a mixture of POE elastomer metallocene, KN resin and metallocene polyethylene, wherein the total mass percentage of POE elastomer metallocene, KN resin and metallocene polyethylene in the mixture is 100%; The intermediate layer (2) consists of 1-3 layers and is composed of a mixture of high-density metallocene material, HDPE and medium-density polyethylene, wherein the sum of the mass percentages of high-density metallocene material, HDPE and medium-density polyethylene in the mixture is 100%. The outer layer (3) is composed of a mixture of high-density metallocene polyethylene, LDPE and an opening agent. The opening agent is an inorganic particle with a particle size of 0.5-5μm. The total mass percentage of high-density metallocene polyethylene, LDPE and opening agent in the mixture is 100%.

2. The high and low temperature PE film for medical device packaging according to claim 1, characterized in that: In the heat-sealing layer (1), the mass percentage of POE elastomer metallocene is 20-40%, the mass percentage of KN resin is 10-20%, and the mass percentage of metallocene polyethylene is 40-70%.

3. The high and low temperature PE film for medical device packaging according to claim 1, characterized in that: In the intermediate layer (2), the mass percentage of high-density metallocene material is 30-50%, the mass percentage of HDPE is 20-40%, and the mass percentage of medium-density polyethylene is 10-30%. When the PE film has a five-layer structure, the intermediate layer (2) includes three sub-layers. The material composition of the three sub-layers is the same as that of the intermediate layer (2), and the total thickness of the three sub-layers accounts for 30-50% of the total thickness of the PE film.

4. A method for processing a high-low temperature PE film for medical device packaging, based on the high-low temperature PE film for medical device packaging as described in any one of claims 1-3, characterized in that, Includes the following steps: Step 1: Raw material pretreatment: The raw materials for the heat-sealing layer (1), intermediate layer (2) and outer layer (3) are dried and sieved. Step 2: Preparation of multilayer co-extrusion melt: The pretreated raw materials of each layer are added to the corresponding extruder, and after being melted and plasticized, they are conveyed to the co-extrusion die head to converge. Step 3: Film blowing and forming: The combined melt is extruded from the co-extrusion die to form a tubular preform, which is then inflated to the target width. Step 4: Cooling and Shaping The inflated film preform is cooled to solidify and shape. Step 5, Traction and Thickness Control: The cured film is then pulled to the next process, and the thickness deviation is adjusted in real time. Step Six: Surface Treatment The outer layer (3) of the film is treated to improve its smoothness; Step 7: Rewinding and Slitting The processed film is rolled up and then cut into sheets.

5. The processing method of a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The drying process is carried out at a temperature of 40-50℃ for 2-3 hours to remove free moisture from the raw materials. The sieving process uses an 80-100 mesh sieve to filter out mechanical impurities and particles that exceed the size limit from the raw materials.

6. The processing method of a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The corresponding extruders include a first extruder for the heat-sealing layer (1) raw material, a second extruder for the intermediate layer (2) raw material, and a third extruder for the outer layer (3) raw material; the screw temperatures of the first extruder are as follows: feeding section 140-150℃, compression section 150-155℃ and homogenization section 155-160℃; the screw temperatures of the second extruder are as follows: feeding section 160-170℃, compression section 170-175℃ and homogenization section 175-180℃; the screw temperatures of the third extruder are as follows: feeding section 150-160℃, compression section 160-165℃ and homogenization section 165-170℃; the melt layers are stacked and merged in the confluence cavity of the co-extrusion die along the stepped flow channel, and the flow channel temperature is maintained at 160-170℃.

7. A method for processing a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The extrusion temperature of the tubular preform is 160-170℃, and the extrusion speed is 3-6m / min. The blow-up process uses oil-free compressed air with an air pressure of 0.2-0.4MPa. The blow-up ratio is set to 1.5-3.0 according to the film thickness, wherein the blow-up ratio of the three-layer structure film is 2.0-3.0, and the blow-up ratio of the five-layer structure film is 1.5-2.

5.

8. A method for processing a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The cooling and shaping process adopts a two-stage cooling method: the first stage is an annular air ring cooling, with the distance between the air ring outlet and the film blank being 5-8cm, the inlet air temperature being 20-25℃, and the air velocity being 4-5m / s; the second stage is water cooling, in which the film blank cooled by the air ring is immersed in cooling water at 20-25℃ for 10-15s, so that the film blank temperature drops to below 40℃.

9. A method for processing a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The traction is achieved using a three-roller traction unit with a traction speed of 5-10 m / min and a traction roller temperature of 30-40℃. The thickness control is achieved by real-time monitoring of the transverse and longitudinal thickness of the film using an online laser thickness gauge. When the thickness deviation exceeds ±0.02 mm, it is corrected by adjusting the ratio of the traction speed to the extrusion speed (1.2-1.5).

10. A method for processing a high and low temperature PE film for medical device packaging according to claim 4, characterized in that: The surface treatment is corona treatment, with a corona power of 2-3kW. The treatment speed is consistent with the traction speed to ensure that the surface tension of the outer layer (3) reaches 38-42dyn / cm. The winding process employs a tension closed-loop control system with a winding tension of 50-80N and a winding speed synchronized with the traction speed. The slitting process utilizes a circular knife slitting machine with a slitting accuracy of ±0.5mm.

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