Medicine packaging composite film and preparation process thereof

Abstract

The invention relates to the technical field of multi-layer composite materials, in particular to a medicine packaging composite film and a preparation process thereof. The problems that a traditional packaging film is poor in durability and poor in heat sealing performance are solved. According to the invention, by adding HDPE with proper molecular weight and proper parts of modification additive, the modified HDPE functional layer forms a'flexible-rigid 'synergistic structure; hydrostatic pressure gradient pressurization is utilized; block copolymerized PP particles are adopted as a main raw material of a modified PP functional layer, and a toughening aid and a grafting aid are added, so that a complete chemical cross-linked network is formed through the synergistic effect of the multiple aids; pre-pressing is conducted through hydrostatic treatment; the durability of the medicine packaging composite film is improved; lLDPE with proper molecular weight is adopted as a main raw material of a modified LLDPE functional layer, a plurality of functional aids are added, and corona treatment, screen film two-way two-step stretching and efficient cutting and rolling are combined, so that the medicine packaging composite film keeps good heat sealing performance.

Description

Technical Field

[0001] The invention relates to the technical field of multilayer composite materials, in particular to a composite film for drug packaging and a preparation process thereof. Background Art

[0002] With the rapid development of the pharmaceutical industry, the functional requirements of pharmaceutical packaging materials are becoming increasingly stringent. Traditional single-layer plastic films can no longer meet the requirements of pharmaceuticals for moisture resistance, light protection, oxidation resistance and long-term stability due to insufficient barrier properties and limited mechanical strength. Based on this, multi-layer composite material technology has become the mainstream solution in the field of pharmaceutical packaging through the synergistic effect of materials with different performances. Its core structure is usually composed of a synthetic resin-based barrier layer, a heat-sealing layer and a printed support layer.

[0003] In a multi-layer composite material system, the choice of synthetic resin directly determines the core performance of the composite film. Currently, widely used materials include polyethylene (PE), polypropylene (PP), polyester (PET), ethylene-vinyl alcohol copolymer (EVOH), etc. For example, polyester resin has good strength and transparency, and can be used for the outer layer to provide protection and display drug information; polyethylene resin has good flexibility and moisture resistance, and can be used for the inner layer in direct contact with drugs. In addition, aluminum foil pharmaceutical composite film has become the mainstream choice for multi-layer composite structures of pharmaceutical packaging composite films because it can provide excellent moisture resistance for drugs. However, aluminum foil is easily pressed and cracked, causing the pharmaceutical packaging composite film to lose its protective function after multiple openings or extrusions; at the same time, the high thermal conductivity of aluminum foil will cause the heat of the packaging film to dissipate rapidly when it is heat-sealed, which requires a higher hot air temperature or a longer heat-sealing time to ensure that the packaging film is melted, but this can easily cause the aluminum foil layer to debond from other layers, and even embrittlement in the heat-sealed area, thereby reducing its heat-sealing performance and durability.

[0004] Therefore, a composite film for drug packaging and a preparation process thereof are proposed. Summary of the invention

[0005] The purpose of the present invention is to provide a pharmaceutical packaging composite film and a preparation process thereof, wherein a modified HDPE functional layer forms a "flexible-rigid" synergistic structure by adding a suitable molecular weight HDPE and a suitable number of modifying additives; hydrostatic gradient pressurization is used; block copolymer PP particles are used as the main raw material of the modified PP functional layer, and toughening additives and grafting additives are added, and the synergistic effect of the multiple additives forms a complete chemical cross-linking network; pre-pressing is performed by hydrostatic treatment; the durability of the pharmaceutical packaging composite film is improved; LLDPE with a suitable molecular weight is used as the main raw material of the modified LLDPE functional layer, a variety of functional additives are added, and corona treatment, two-way two-step stretching of the screen film and efficient cutting and winding are combined to enable the pharmaceutical packaging composite film to maintain good heat sealing performance.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] In one aspect, the present invention provides a process for preparing a composite film for drug packaging. The process for preparing the composite film for drug packaging is as follows:

[0008] Pre-coating an interlayer adhesive between the outer cover (modified HDPE functional layer), the inner cover (modified polypropylene functional layer) and the gasket (modified LLDPE functional layer) to obtain a pre-coated composite film;

[0009] Performing hydrostatic treatment on the pre-coated composite membrane to obtain a composite membrane;

[0010] The composite film is stretched longitudinally and transversely by two-step bidirectional stretching of the screen film, and then an anti-fog coating is applied to obtain an anti-fog stretched composite film;

[0011] The anti-fog stretch composite film is cut and rolled up by adopting high-efficiency cutting and rolling to obtain the composite film for pharmaceutical packaging.

[0012] Preferably, the specific operation flow of the hydrostatic treatment is: insert the pre-coated composite film into the core tube of the hydraulic hose crimping machine; preheat the core tube to 70°C, and pre-press for 10-15s at 5-8MPa; perform gradient pressurization, the pressures of the gradient pressurization are 8MPa, 12MPa and 15MPa, respectively, the interval between each level of pressurization is 5s, and the pressure at each level is maintained for 10s; finally, perform precision pressing and shaping, the mold temperature is maintained at 40-50°C, and hot pressing is performed at a pressure of 18MPa for 25s; the pressure is reduced to 5MPa, maintained for 30s, cooled to room temperature, and demolded using a pneumatic ejection device to obtain a composite film.

[0013] Preferably, the modified HDPE functional layer is made of the following raw materials in parts by weight: 100 parts of high-density polyethylene (HDPE), 1.5-2.0 parts of modified nano-silicon dioxide, 0.8-1.2 parts of nano-talc, 0.35-0.45 parts of polyisobutylene (PIB), 0.06 parts of hindered amine light stabilizer (HALS), and 0.03 parts of β-crystal nucleating agent (TMB-5).

[0014] Preferably, the preparation method of the modified HDPE functional layer is as follows: premixing high-density polyethylene (HDPE) with modified nano-silicon dioxide and nano-talc at 65°C for 5 minutes; adding liquid polyisobutylene (PIB) and hindered amine light stabilizer (HALS), and continuing to mix until uniform dispersion; finally adding β-crystalline nucleating agent (TMB-5), mixing at 40°C for 3 minutes to obtain melt-modified HDPE; transferring the melt-modified HDPE to a co-rotating twin-screw extruder, setting the feed section temperature to 150°C, the melt plasticization section temperature to 170°C, the homogenization mixing section temperature to 185°C and the extrusion section temperature to 190°C, completing the melt extrusion process, and controlling the temperature of the cooling roller to 25°C and the contact pressure to 0.2-0.4MPa; obtaining the modified HDPE functional layer after corona treatment; the molecular weight of the high-density polyethylene is 1.0×10 5 -1.5×10 5 g / mol.

[0015] Preferably, the preparation method of modified nano-silica is as follows: drying 10 parts of nano-silica (particle size 30 nm) in an oven at 120° C. for 2 h to obtain dry nano-silica; adding 50 parts of anhydrous ethanol to a reaction kettle, slowly adding 0.5 parts of a silane coupling agent (KH-550) under stirring, the stirring speed is 300 rpm, and the stirring is continued for 10 min; slowly adding 5 parts of deionized water, and adding dilute hydrochloric acid to adjust the pH to 5 to obtain a modified solution 1; adding the dry nano-silica to the modified solution 1 for ultrasonic dispersion, and performing centrifugal treatment and drying to obtain modified nano-silica.

[0016] Preferably, the modified PP functional layer is made of the following raw materials in parts by weight: 100 parts of block copolymer PP particles (PP-b-EPR, 3 mm), 8-12 parts of POE elastomer, 0.5-1.0 parts of SEBS elastomer, 0.2-0.5 parts of maleic anhydride grafted PP (MAH-g-PP), 0.2 parts of erucamide lubricant, and 0.07 parts of nucleating agent.

[0017] Preferably, the preparation method of the modified PP functional layer is as follows: the block copolymer PP particles are dried in a drying oven at 80°C for 4 hours, the POE elastomer and the SEBS elastomer are preheated at 60°C for 30 minutes, and then added to a high-speed mixer at a temperature of 55°C and mixed until they are uniformly dispersed; maleic anhydride grafted PP (MAH-g-PP) and dibenzylidene sorbitol derivative (DBS) nucleating agent are added, and the mixture is continued to be mixed at a speed of 500-600rpm for 2 minutes; finally, erucic acid amide migration type lubricant is added at a speed of 200rpm and mixed for 1 minute to obtain melt-modified PP; the melt-modified PP is melt-extruded in a co-rotating twin-screw extruder with a feed section temperature of 160°C, a melt plasticization section temperature of 175°C, a mixing and dispersion section temperature of 185°C, and a homogenization extrusion section temperature of 200°C, and a modified PP functional layer is obtained under the action of a cooling roller; the molecular weight of the block copolymer PP particles is 2.0×10 5 g / mol.

[0018] Preferably, the modified LLDPE functional layer is made of the following raw materials in parts by weight: 75-80 parts of linear low-density polyethylene (LLDPE), 18 parts of ethylene-acrylic acid copolymer (EAA), 5-8 parts of ethylene-vinyl acetate copolymer (EVA), 2-3 parts of modified nano-kaolin, and 0.06 parts of antioxidant.

[0019] Preferably, the preparation method of the modified LLDPE functional layer is as follows: adding dried linear low-density polyethylene (LLDPE), ethylene-acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer, and modified nano-kaolin to the main feeding port of the extruder; adding an antioxidant through a side feeder at the second zone position; setting the vacuum pump pressure of the mixing section of the twin-screw extruder to -0.08 MPa for melt mixing; then, the melt is extruded through a die head and bonded to a cooling roller to form a uniform modified LLDPE film; corona treatment is performed by a high-voltage generator with a power of 5-7 kW and a frequency of 200 kHz to obtain a modified LLDPE functional layer; the antioxidant is obtained by compounding antioxidant 1076 and antioxidant 168 in a ratio of 1:1; the molecular weight of the linear low-density polyethylene is 4.0×10 4 -6.0×10 4 g / mol.

[0020] Preferably, the preparation method of modified nano-kaolin is as follows: drying 10 parts of nano-kaolin for 4 hours and passing through a 200-mesh sieve to obtain primary-screened nano-kaolin; adding 40 parts of anhydrous ethanol to a reaction kettle, and slowly adding 3 parts of silane coupling agent KH-560 under stirring; adding 3 parts of deionized water and 0.5 parts of dilute hydrochloric acid to adjust the pH to 5, and continuing to stir for 20 minutes to obtain a modified solution 2; adding the primary-screened nano-kaolin to the modified solution 2, ultrasonically dispersing and stirring at a constant temperature; after the reaction is completed, centrifugation and drying are performed to obtain the modified nano-kaolin.

[0021] Preferably, the specific operation process of the bidirectional two-step stretching of the screen film is as follows: preheating the composite film to 80°C, using a multi-roller longitudinal stretching unit (equipped with an infrared screen film heating function), setting the stretching ratio to 3.0 times at 95°C and a stretching speed of 12-15m / min, and longitudinally stretching the composite film; during the cooling process, setting the temperature of the cooling roller to 45°C to quickly shape the longitudinally stretched composite film; preheating the longitudinally stretched composite film to 110°C, using a chain clamp tenter (equipped with a screen film hot air circulation system), setting the stretching ratio to 3.3-3.5 times, and transversely stretching at 125°C; then heat setting at a temperature of 210°C; after the heat setting is completed, the stretched composite film is cooled by air cooling at a cooling rate of 3°C / s to 50°C; cooling to room temperature to obtain a stretched composite film; coating a 0.2μm anti-fog coating (silicon dioxide nanosol) on the upper surface of the stretched composite film to obtain an anti-fog stretched composite film.

[0022] Preferably, the specific operation process of cutting and winding is: the unwinding shaft releases the anti-fog stretch composite film at a constant tension of 80N / m, and performs laser precision cutting at a power of 250W; nitrogen is blown synchronously at a pressure of 0.5MPa; the winding speed is controlled to be 25-30m / min to wind up the cut anti-fog stretch composite film to obtain a pharmaceutical packaging composite film.

[0023] Preferably, the interlayer adhesive is a two-component polyurethane adhesive; the coating amount of the two-component polyurethane adhesive between the outer cover and the inner cover is 3.0 g / m 2 ; The coating amount between the inner cover and the gasket is 2.5g / m 2 .

[0024] On the other hand, the present invention also provides a composite film for pharmaceutical packaging, which is prepared by any one of the above preparation methods; the outer cover has a thickness of 1.0 mm; the inner cover has a thickness of 0.6 mm; and the gasket has a thickness of 0.9 mm.

[0025] Unless otherwise specified, parts in the present invention refer to parts by weight, and molecular weight refers to number average molecular weight.

[0026] Compared with the prior art, the present invention has the following beneficial effects:

[0027] 1. In the process of preparing the modified HDPE functional layer, high-density polyethylene with a suitable molecular weight is added to provide sufficient toughness and suitable viscosity for the melting process; suitable portions of modified nano-silicon dioxide and polyisobutylene are added, and the two act synergistically to promote uniform mixing inside the filler, so that the modified HDPE functional layer forms a "flexible-rigid" synergistic structure; the pre-coated composite film is gradient pressurized using the hydrostatic principle of equal circumferential pressure, and the step-by-step pressure maintenance of the gradient pressurization provides a buffer time for the curing of the adhesive, which can effectively fill the tiny bubbles and gaps between the layers; at the same time, the layers are orderly stretched and stacked under pressure; while maintaining the tensile strength, the elongation is significantly improved, thereby improving the durability of the composite film for pharmaceutical packaging.

[0028] 2. When preparing the modified PP functional layer, block copolymer PP particles are used as the main raw material, and appropriate amounts of toughening agents and grafting agents are added. Multiple additives work synergistically to form a complete chemical cross-linking network, which significantly improves the compatibility of the interface of the modified PP functional layer and reduces the stress concentration points caused by phase separation; induces the block copolymer PP molecular chains to form smaller and more uniform spherulites, thereby refining the crystal structure; reduces the thermal shrinkage of the modified PP functional layer; and at the same time, through the hydrostatic treatment pre-pressing process, the interlayer adhesive initially penetrates into the interface of the outer cover, the inner cover and the gasket, discharges the entrained air and residual solvent, forms a continuous bonding interface, and provides a uniform stress distribution basis for subsequent gradient pressurization, thereby improving the durability of the pharmaceutical packaging composite film.

[0029] 3. When preparing the modified LLDPE functional layer, linear low-density polyethylene is used as the main raw material, and an appropriate amount of functional additives are added, and combined with corona treatment, a dense network structure is formed inside the modified LLDPE functional layer, and a microscopic rough structure is formed on the surface, thereby improving the heat sealing strength and sealing durability of the pharmaceutical packaging composite film. The screen film is stretched in two directions in two steps, overcoming the technical problems of complex equipment, large investment and high cost of the "flat film bidirectional one-step simultaneous stretching" method.

[0030] 4. When preparing the modified LLDPE functional layer, add linear low-density polyethylene with an appropriate molecular weight, and combine it with the appropriate stretch ratio in the two-way two-step stretching process of the screen film. By reducing the initial heat sealing temperature, improving high temperature tolerance, optimizing the molecular chain distribution and enhancing process compatibility, the heat sealing temperature window width of the pharmaceutical packaging composite film is expanded; it not only improves the fault tolerance of the production process, but also ensures that the pharmaceutical packaging composite film has high heat sealing strength and sealing stability. The use of efficient cutting and winding reduces the probability of scratches on the outer surface of the composite film and improves the product cutting quality and efficiency; further stabilizes the heat sealing temperature window width of the pharmaceutical packaging composite film, so that it maintains good heat sealing performance under heat sealing conditions. BRIEF DESCRIPTION OF THE DRAWINGS

[0031] Figure 1The heat sealing performance test results of Examples 13-18 of the present invention and Comparative Examples 11-16 are shown in FIG. DETAILED DESCRIPTION

[0032] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] See also Figure 1 The present invention provides a composite film for pharmaceutical packaging and a preparation process thereof, and the technical scheme is as follows:

[0034] The substance information involved in the present invention is as follows:

[0035] Two-component polyurethane adhesive was purchased from Youxing Shark (Shanghai) Technology Co., Ltd.; silica nanosol was purchased from Shandong Yinfeng Nano New Materials Co., Ltd.; hydraulic hose crimping machine was purchased from Tianjin Fuleer Technology Development Co., Ltd.; high-density polyethylene (HDPE), block copolymer PP particles (PP-b-EPR, 3mm), and linear low-density polyethylene (LLDPE) were all purchased from Dow Chemical Company; nano talc powder (0.5μm) was purchased from Foshan Jinlinda Chemical Co., Ltd.; nano silica (particle size 30nm) was purchased from Ningbo Luofei Nano Technology Co., Ltd.

[0036] Example 1

[0037] On one hand, the present invention provides a preparation process of a composite film for drug packaging, wherein the composite film for drug packaging consists of an outer cover, an inner cover, and a gasket; the outer cover is a modified HDPE functional layer; the inner cover is a modified polypropylene functional layer; and the gasket is a modified LLDPE functional layer;

[0038] The modified HDPE functional layer is made of the following raw materials in parts by weight: 100 parts of high-density polyethylene (HDPE), 1.5 parts of modified nano-silicon dioxide, 1.0 parts of nano-talc, 0.35 parts of polyisobutylene (PIB), 0.06 parts of hindered amine light stabilizer (HALS), and 0.03 parts of β-crystal nucleating agent (TMB-5); the molecular weight of the high-density polyethylene is 1.4×10 5 g / mol.

[0039] The preparation method of the modified HDPE functional layer is as follows: premixing high-density polyethylene (HDPE) with modified nano-silicon dioxide and nano-talc at 65°C for 5 minutes; adding liquid polyisobutylene (PIB) and hindered amine light stabilizer (HALS), and continuing to mix until uniformly dispersed; finally adding β-crystalline nucleating agent (TMB-5), mixing at 40°C for 3 minutes to obtain melt-modified HDPE; transferring the melt-modified HDPE to a co-rotating twin-screw extruder, setting the feed section temperature to 150°C, the melt plasticization section temperature to 170°C, the homogenization mixing section temperature to 185°C and the extrusion section temperature to 190°C to complete the melt extrusion process, and controlling the temperature of the cooling roller to 25°C and the contact pressure to 0.3MPa; and obtaining the modified HDPE functional layer after corona treatment.

[0040] The preparation method of modified nano-silica is as follows: drying 10 parts of nano-silica (particle size 30 nm) in an oven at 120° C. for 2 hours to obtain dry nano-silica; adding 50 parts of anhydrous ethanol to a reaction kettle, slowly adding 0.5 parts of a silane coupling agent (KH-550) under stirring, the stirring speed is 300 rpm, and the stirring is continued for 10 minutes; slowly adding 5 parts of deionized water, and adding dilute hydrochloric acid to adjust the pH to 5 to obtain a modified solution 1; adding the dry nano-silica to the modified solution 1 for ultrasonic dispersion, and performing centrifugal treatment and drying to obtain the modified nano-silica.

[0041] The modified PP functional layer is made of the following raw materials in parts by weight: 100 parts of block copolymer PP particles (PP-b-EPR, 3 mm), 8 parts of POE elastomer, 0.5 parts of SEBS elastomer, 0.2 parts of maleic anhydride grafted PP (MAH-g-PP), 0.2 parts of erucic acid amide lubricant, and 0.07 parts of nucleating agent; the molecular weight of the block copolymer PP particles is 2.0×10 5 g / mol.

[0042] The preparation method of the modified PP functional layer is as follows: drying the block copolymer PP particles in a drying oven at 80°C for 4 hours, preheating the POE elastomer and the SEBS elastomer at 60°C for 30 minutes, adding them together into a high-speed mixer at a temperature of 55°C, and mixing until they are evenly dispersed; adding maleic anhydride grafted PP (MAH-g-PP) and dibenzylidene sorbitol derivative (DBS) nucleating agent, and continuing to mix at a speed of 500rpm for 2 minutes; finally, adding erucic acid amide migration type lubricant at a speed of 200rpm and mixing for 1 minute to obtain melt-modified PP; the melt-modified PP completes the melt extrusion process in a co-rotating twin-screw extruder with a feeding section temperature of 160°C, a melt plasticizing section temperature of 175°C, a mixing and dispersing section temperature of 185°C, and a homogenizing extrusion section temperature of 200°C, and obtains the modified PP functional layer under the action of a cooling roller.

[0043] The modified LLDPE functional layer is made of the following raw materials in parts by weight: 75 parts of linear low-density polyethylene (LLDPE), 18 parts of ethylene-acrylic acid copolymer (EAA), 5 parts of ethylene-vinyl acetate copolymer (EVA), 3 parts of modified nano-kaolin, and 0.06 parts of antioxidant; the molecular weight of the linear low-density polyethylene is 4.0×10 4 g / mol.

[0044] The preparation method of the modified LLDPE functional layer is as follows: adding dried linear low-density polyethylene (LLDPE), ethylene-acrylic acid copolymer (EAA), ethylene-vinyl acetate copolymer, and modified nano-kaolin to the main feeding port of the extruder; adding an antioxidant through a side feeder at the second zone position; setting the vacuum pump pressure of the mixing section of the twin-screw extruder to -0.08MPa for the melt mixing process; then, the melt is extruded through a die head and bonded to a cooling roller to form a uniform modified LLDPE film; corona treatment is performed by a high-voltage generator with a power of 7kW and a frequency of 200kHz to obtain a modified LLDPE functional layer; and 0.03 weight parts of antioxidant 1076 and 0.03 weight parts of antioxidant 168 are added to the antioxidant.

[0045] The preparation method of modified nano-kaolin is as follows: drying 10 parts of nano-kaolin for 4 hours and passing through a 200-mesh sieve to obtain primary-screened nano-kaolin; adding 40 parts of anhydrous ethanol into a reaction kettle, and slowly adding 3 parts of silane coupling agent KH-560 under stirring; adding 3 parts of deionized water and 0.5 parts of dilute hydrochloric acid to adjust the pH to 5, and continuing to stir for 20 minutes to obtain a modified solution 2; adding the primary-screened nano-kaolin into the modified solution 2, ultrasonically dispersing and stirring at a constant temperature; after the reaction is completed, centrifugation and drying are performed to obtain the modified nano-kaolin.

[0046] The outer cover (modified HDPE functional layer), the inner cover (modified polypropylene functional layer) and the gasket (modified LLDPE functional layer) are pre-coated with an interlayer adhesive to obtain a pre-coated composite film; the interlayer adhesive is a two-component polyurethane adhesive; the coating amount of the two-component polyurethane adhesive between the outer cover and the inner cover is 3.0 g / m 2 ; The coating amount between the inner cover and the gasket is 2.5g / m 2 .

[0047] The pre-coated composite film is put into the core tube of the hydraulic hose crimping machine; the core tube is preheated to 70°C and pre-pressed at 8MPa for 15s; gradient pressurization is performed, and the pressures of the gradient pressurization are 8MPa, 12MPa and 15MPa respectively, the interval between each pressurization is 5s, and the pressure of each level is maintained for 10s; finally, precision pressing is performed, the mold temperature is maintained at 45°C, and hot pressing is performed at a pressure of 18MPa for 25s; the pressure is reduced to 5MPa, maintained for 30s, cooled to room temperature, and demolded using a pneumatic ejection device to obtain a composite film.

[0048] The composite film is preheated to 80°C, and a multi-roller longitudinal stretching unit (equipped with an infrared screen film heating function) is used to set the stretching ratio to 3.0 times at 95°C and a stretching speed of 15m / min to longitudinally stretch the composite film; during the cooling process, the temperature of the cooling roller is set to 45°C to quickly set the longitudinally stretched composite film; the longitudinally stretched composite film is preheated to 110°C, and a chain clamp tenter (equipped with a screen film hot air circulation system) is used to transversely stretch the composite film at 125°C, and the stretching ratio is set to 3.5 times; then heat setting is performed at a temperature of 210°C; after the heat setting is completed, the stretched composite film is cooled by air cooling at a cooling rate of 3°C / s to 50°C; it is cooled to room temperature to obtain a stretched composite film; a 0.2μm anti-fog coating (silicon dioxide nanosol) is coated on the upper surface of the stretched composite film to obtain an anti-fog stretched composite film.

[0049] The unwinding shaft releases the anti-fog stretch composite film at a constant tension of 80N / m, and the laser is precisely cut at a power of 250W; nitrogen is simultaneously purged at a pressure of 0.5MPa; the winding speed is controlled to be 25m / min to wind up the cut anti-fog stretch composite film to obtain a pharmaceutical packaging composite film.

[0050] The thickness of the outer cover of the pharmaceutical packaging composite film is 1.0mm; the thickness of the inner cover is 0.6mm; and the thickness of the gasket is 0.9mm.

[0051] Embodiment 2-6

[0052] Referring to the preparation method and parameter conditions of Example 1, the specific differences are shown in Table 1; the contact pressure in Table 1 is the contact pressure of the cooling roller during the preparation of the modified HDPE functional layer; the mold temperature is the temperature of the precision pressing mold during the hydrostatic treatment.

[0053] Comparative Example 1

[0054] The preparation method and parameter conditions of Example 1 are referred to, except that in the preparation process of the modified HDPE functional layer, the molecular weight of the high-density polyethylene is 1.2×10 3 g / mol.

[0055] Comparative Example 2

[0056] The preparation method and parameter conditions of Example 1 are referred to, except that in the preparation process of the modified HDPE functional layer, the molecular weight of the high-density polyethylene is 1.2×10 7 g / mol.

[0057] Comparative Example 3

[0058] The preparation method and parameter conditions are referred to in Example 1, except that modified nano-silicon dioxide is not added during the preparation of the modified HDPE functional layer.

[0059] Comparative Example 4

[0060] The preparation method and parameter conditions are the same as those of Example 1, except that 5 parts of polyisobutylene are added during the preparation of the modified HDPE functional layer.

[0061] Comparative Example 5

[0062] The preparation method and parameter conditions are referred to as those of Example 1, except that after the pre-coated composite film is inserted into the core tube of the hydraulic hose crimping machine for pre-compression, no gradient pressurization treatment is performed, and precision pressing and shaping is performed directly at a temperature of 25°C.

[0063] Comparative Example 6

[0064] The preparation method and parameter conditions are referred to as those of Example 1, except that after the pre-coated composite film is inserted into the core tube of the hydraulic hose crimping machine for pre-compression, no gradient pressurization treatment is performed, and precision pressing and shaping is performed directly at a temperature of 80°C.

[0065] Experimental Example 1 Durability Test

[0066] Cut a 100mm×100mm sample to ensure that the sample has no defects and the edges are flat; condition the sample in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 5 hours to eliminate the influence of the environment on the test results; according to the standard YBB 00122003-2015 "General Rules for Composite Films and Bags for Pharmaceutical Packaging", use the QX-W100 composite film elongation tester to measure the elongation of the sample; the calculation formula is: The specific test results are shown in Table 1.

[0067] Table 1 Durability test of Examples 1-6 and Comparative Examples 1-5

[0068]

[0069] As shown in the elongation data of the pharmaceutical packaging composite film in Table 1, the transverse elongation values ​​of the pharmaceutical packaging composite films of Examples 1-6 are stable at 135%-150%, and the longitudinal elongation values ​​are stable at 110%-130%, indicating that the pharmaceutical packaging composite films of Examples 1-6 have good ductility. In Comparative Examples 1-2, the molecular weight of the high-density polyethylene raw material added during the preparation of the modified HDPE functional layer is too low or too high, which will lead to a decrease in the elongation of the composite film. The molecular chain of low molecular weight high density polyethylene becomes shorter and the crystallinity becomes higher, which makes it difficult to effectively coat nano silica and talcum powder. The filler is unevenly dispersed during melting, thus forming a stress concentration point, which makes it easier to break during melt extrusion, resulting in increased brittleness of the outer cover of the pharmaceutical packaging composite film, a significant decrease in elongation during molding and use, and a significant decrease in durability; while the molecular chain of high molecular weight high density polyethylene is too long, and the long molecular chain is easy to bond during the melting process, thus hindering the uniform dispersion of nano fillers; and high molecular weight high density polyethylene requires a higher melting temperature. Excessive temperature will cause thermal decomposition of polyisobutylene, weakening the plasticizing effect while increasing the rigidity of the outer cover, and cannot meet the overall extension performance requirements of the pharmaceutical packaging composite film. The high density polyethylene added in the original preparation process has a moderate molecular weight and a moderate molecular chain length, which can provide sufficient toughness for the good entanglement of the molecular chain during the melting process, while avoiding excessive crystallization catalysis inside the filler; provide a suitable viscosity for the melt, ensure uniform dispersion and stable extrusion of nanoparticles under low melting temperature conditions, so that the prepared pharmaceutical packaging composite film has good ductility.

[0070] The difference from Comparative Example 3 is that if modified nano-silica is not added during the preparation of the modified HDPE functional layer, the elongation of the pharmaceutical packaging composite film will be greatly reduced; because in the process of preparing the modified HDPE functional layer, the modified nano-silica can synergize with the β-crystal nucleating agent (TMB-5) to induce the high-density polyethylene to form smaller and more uniform crystals; at the same time, the dispersed network of the modified nano-silica can provide anchoring points for the plasticizer polyisobutylene, so that the modified HDPE functional layer forms a "flexible-rigid" synergistic structure; the molecular chains inside the modified HDPE functional layer filler are more easily oriented and extended under the action of external forces, and the molecular chains slide more smoothly during stretching, thereby improving the elongation of the pharmaceutical packaging composite film.

[0071] Comparative Example 4: Adding too much polyisobutylene during the preparation of the modified HDPE functional layer will weaken the van der Waals force between high-density polyethylene, resulting in the loss of rigidity of the outer cover, showing excessive elasticity similar to rubber, which will undergo irreversible deformation when subjected to external force, thereby losing the shape retention ability required for packaging; and excessive polyisobutylene will excessively coat the nanofiller, reduce the bonding force between the nanofiller and the high-density polyethylene interface, reduce the viscosity of the melt, and ultimately cause the pharmaceutical packaging composite film to break prematurely during the stretching process, and the elongation will decrease instead. The appropriate amount of polyisobutylene is used as a liquid plasticizer in the filler, and the flexibility of its molecular chain can effectively reduce the crystallinity of high-density polyethylene; at the same time, the lubricating effect of polyisobutylene can reduce the melt viscosity, promote the uniform mixing of high-density polyethylene and nanofillers, and in the melt extrusion process, polyisobutylene is inserted between the high-density polyethylene molecular chains, reducing the friction between the chains and improving the fluidity of the melt, thereby giving the outer cover better ductility and flexibility.

[0072] In Comparative Examples 5-6, when the pre-coated composite film is subjected to hydrostatic treatment, the gradient pressure treatment is not performed, and high pressure is directly applied, which will cause the adhesive to be quickly squeezed to a local area, resulting in uneven adhesive coverage, a large number of bubbles remaining between interfaces, a large difference in the bonding strength of the interfaces, and an increase in interlayer stress, thereby reducing the overall ductility of the pharmaceutical packaging composite film; directly performing precision pressing and shaping at too low a temperature will cause the fluidity of the adhesive to deteriorate at low temperatures, the outer cover, the inner cover and the gasket to have a large hardness at low temperatures, the interlayer bonding force to weaken, and the interlayer separation and brittle fracture are easy to occur during subsequent testing; while directly performing precision pressing and shaping at high temperatures, the adhesive will significantly soften under high temperature conditions, pyrolysis will occur, and the layers cannot be effectively solidified, resulting in the inability to form a complete pharmaceutical packaging composite film as a whole, thereby causing the elongation of the pharmaceutical packaging composite film to decrease. The step-by-step pressure maintenance of the gradient pressurization provides a buffer time for the curing of the adhesive, which can effectively fill the tiny bubbles and gaps between the layers; at the same time, the layers are orderly stretched and stacked under pressure; and the elongation is significantly improved while maintaining the tensile strength.

[0073] Examples 7-12

[0074] Referring to the preparation method and parameter conditions of Example 3, the specific differences are shown in Table 2; the rotation speed in Table 2 is the mixing rotation speed after adding maleic anhydride grafted PP and nucleating agent in the preparation process of the modified PP functional layer; the pre-pressing pressure and pre-pressing time are the pre-pressing pressure and pre-pressing time when the pre-coated composite film is inserted into the core tube of the hydraulic hose crimping machine.

[0075] Comparative Example 7

[0076] The preparation method and parameter conditions are referred to in Example 3, except that after the pre-coated composite film is inserted into the core tube of the hydraulic hose crimping machine, the pre-coated composite film is not pre-pressed, and gradient pressurization is directly performed.

[0077] Comparative Example 8

[0078] The preparation method and parameter conditions are referred to in Example 3, except that when preparing the modified PP functional layer, the raw block copolymer PP particles are replaced with polypropylene (PP) particles.

[0079] Comparative Example 9

[0080] The preparation method and parameter conditions are referred to in Example 3, except that 1 part of POE elastomer and 12 parts of SEBS elastomer are added when preparing the modified PP functional layer.

[0081] Comparative Example 10

[0082] The preparation method and parameter conditions are referred to in Example 3, except that maleic anhydride grafted PP is not added when preparing the modified PP functional layer.

[0083] Experimental Example 2 Durability Test

[0084] Cut a 100mm×100mm sample and ensure that the sample has no defects and the edges are flat; adjust the sample in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 hours; hang the sample in a heat shrinkage tester, set the temperature to 120±2℃, and the heating time is 5min. After taking it out, cool it to room temperature and measure the size of the sample after shrinkage; measure it according to the standard YBB 00122003-2015 "General Rules for Composite Films and Bags for Pharmaceutical Packaging"; the calculation formula is: The specific test results are shown in Table 2.

[0085] Table 2 Durability test of Examples 7-12 and Comparative Examples 7-10

[0086]

[0087] As shown in the heat shrinkage data of the pharmaceutical packaging composite film in Table 2, the transverse heat shrinkage values ​​of the pharmaceutical packaging composite films of Examples 7-12 are all less than 1.20%, and the longitudinal heat shrinkage values ​​are all less than 1.90%, indicating that the pharmaceutical packaging composite films of Examples 7-12 have good deformation resistance. In Comparative Example 7, after the pre-coated composite film is inserted into the core tube of the hydraulic hose crimping machine, the pre-coated composite film is not pre-pressed, and gradient pressurization is directly performed; a large number of bubbles will remain between the layers, and will expand due to heat during the subsequent precision pressing and shaping to form micropores; these micropores will intensify the local shrinkage due to heat, thereby increasing the transverse and longitudinal heat shrinkage rates of the pharmaceutical packaging composite film. During the hydrostatic treatment process, the pre-pressing pressure forces the interlayer adhesive to initially penetrate into the interface of the outer cover, the inner cover and the gasket, expel the entrained air and residual solvent, form a continuous bonding interface, and provide a uniform stress distribution basis for subsequent gradient pressurization.

[0088] Comparative Example 8: When preparing the modified PP functional layer, the raw block copolymer PP particles are replaced with PP particles; this will lead to a significant increase in the thermal shrinkage rate of the pharmaceutical packaging composite film. This is because ordinary PP particles are homopolymer PP or random copolymer PP, lacking a soft and hard phase separation structure; while the block copolymer PP particles are composed of propylene homopolymer segments and ethylene-propylene copolymer segments alternately, and have a soft and hard phase separation structure; the soft satin structure has better compatibility with POE elastomers and SEBS elastomers, promoting uniform dispersion of the melt system, thereby reducing interface defects; the hard segment structure can give the outer cover a certain mechanical strength; this makes the melt strength of the block copolymer PP particles higher than that of the PP particles, can reduce the overall crystallinity of the melt filler, form a uniform film layer during the biaxial stretching process, and reduce the thermal shrinkage rate of the generated pharmaceutical packaging composite film when heated.

[0089] In Comparative Example 9, 1 part of POE elastomer and 12 parts of SEBS elastomer were added during the preparation of the modified PP functional layer; POE elastomer is the core component for toughening the modified PP functional layer, and a large reduction in its dosage will result in insufficient rubber phase content in the modified PP functional layer; excessive SEBS elastomer content will significantly increase the viscosity of the melt, hinder the heterogeneous nucleation of dibenzylidene sorbitol derivatives, thereby generating coarse spherulites, resulting in poor melt fluidity during melt extrusion and uneven thickness of the generated modified PP functional layer, thereby increasing the thermal shrinkage rate of the pharmaceutical packaging composite film.

[0090] The difference in Comparative Example 10 is that maleic anhydride grafted PP is not added when preparing the modified PP functional layer; the carboxylic acid group of maleic anhydride grafted PP can chemically react with the ethylene segment in the block copolymer PP, the POE elastomer and the unsaturated bonds in the SEBS elastomer, thereby forming a complete chemical cross-linking network, which significantly improves the compatibility of the interface of the modified PP functional layer and reduces the stress concentration points caused by phase separation; the polar end of the maleic anhydride grafted PP can also act as a nucleating agent to cooperate with the dibenzylidene sorbitol derivative nucleating agent to induce the block copolymer PP molecular chain to form smaller and more uniform spherulites, thereby refining the crystalline structure; reducing the overall thermal shrinkage of the modified PP functional layer and the pharmaceutical packaging composite film.

[0091] Examples 13-18

[0092] Referring to the preparation method and parameter conditions of Example 11, the specific differences are shown in Table 3; the power in Table 3 is the power of the modified LLDPE film through the corona treatment of the high-voltage generator; the stretching speed is the stretching speed of the composite film in the multi-roller longitudinal stretching unit during the bidirectional two-step stretching process of the screen film.

[0093] Comparative Example 11

[0094] The preparation method and parameter conditions are similar to those of Example 11, except that when modifying the LLDPE functional layer, the raw material linear low-density polyethylene is replaced by polyethylene.

[0095] Comparative Example 12

[0096] The preparation method and parameter conditions are the same as those of Example 11, except that ethylene-vinyl acetate copolymer is not added when modifying the LLDPE functional layer.

[0097] Comparative Example 13

[0098] The preparation method and parameter conditions are similar to those of Example 11, except that modified nano-kaolin is not added when modifying the LLDPE functional layer.

[0099] Comparative Example 14

[0100] The preparation method and parameter conditions are referred to in Example 11, except that when modifying the LLDPE functional layer, the modified LLDPE film is not subjected to corona treatment by a high voltage generator.

[0101] Comparative Example 15

[0102] The preparation method and parameter conditions are referred to in Example 11, except that in the bidirectional two-step stretching process of the screen film, a multi-roller longitudinal stretching unit is used to longitudinally stretch the composite film at a stretching speed of 5 m / min.

[0103] Comparative Example 16

[0104] The preparation method and parameter conditions are referred to in Example 11, except that in the bidirectional two-step stretching process of the screen film, a multi-roller longitudinal stretching unit is used to longitudinally stretch the composite film at a stretching speed of 30 m / min.

[0105] Experimental Example 3 Heat Sealing Performance Test

[0106] Cut a 100mm×15mm sample to ensure that the sample has no defects and the edges are flat; condition the sample in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24h; put the sample into an integrated heat seal strength tester with a preset temperature of 140℃, stretch it at a speed of 300mm / min until it breaks, and record the maximum force value; the specific test results are shown in Table 3 and Figure 1 shown.

[0107] Table 3 Heat sealing performance test of Examples 13-18 and Comparative Examples 11-16

[0108]

[0109]

[0110] As shown in Table 3 and Figure 1 As shown in the heat seal strength data of the pharmaceutical packaging composite film, the transverse heat seal strength values ​​of the pharmaceutical packaging composite films of Examples 13-18 are stable in the range of 23.0-26.0N, and the longitudinal heat seal strength values ​​are stable in the range of 26.0-29.0N, indicating that the pharmaceutical packaging composite films of Examples 13-18 have good heat seal performance. In Comparative Example 11, when preparing the modified LLDPE functional layer, the raw material linear low-density polyethylene is replaced with polyethylene; linear low-density polyethylene has the characteristics of high toughness, low heat shrinkage, and is easy to process and is superior to polyethylene. If the linear low-density polyethylene is replaced with polyethylene, the puncture resistance of the modified LLDPE functional layer will decrease, the heat seal temperature will increase, the barrier performance will deteriorate, and the heat shrinkage rate will increase, resulting in a deterioration in the heat seal strength of the pharmaceutical packaging composite film.

[0111] The difference between Comparative Examples 12-13 is that when preparing the modified LLDPE functional layer, ethylene-vinyl acetate copolymer and modified nano-kaolin are not added respectively, which will lead to a decrease in the heat sealing strength of the pharmaceutical packaging composite film; this is because ethylene-vinyl acetate copolymer and linear low-density polyethylene (melting temperature 120-130°C) form a polarity gradient transition interface at a lower temperature, which improves the compatibility of the filler inside the modified LLDPE functional layer; the active groups on the surface of the modified kaolin can be combined with the polar segments of the ethylene-vinyl acetate copolymer through hydrogen bonds, and can also form a dense network structure with the linear low-density polyethylene molecular chain; the modified LLDPE functional layer generated by the synergistic action of ethylene-vinyl acetate copolymer and modified nano-kaolin with linear low-density polyethylene has good heat sealing strength. In comparative example 14, when preparing the modified LLDPE functional layer, the heat seal strength of the pharmaceutical packaging composite film prepared by not subjecting the modified LLDPE film to corona treatment by a high-voltage generator will be reduced; because the corona treatment makes the modified LLDPE functional layer easier to spread and penetrate into the bonded surface during the hot pressing process, and forms a microscopic rough structure on the surface of the modified LLDPE functional layer through micro-etching, thereby improving the heat seal strength and sealing durability of the pharmaceutical packaging composite film. In comparative examples 15-16, during the two-step bidirectional stretching process of the screen film, a multi-roller longitudinal stretching unit is used to longitudinally stretch the composite film at an excessively low or excessively high stretching speed; both will destroy the interlayer bonding ability of the pharmaceutical packaging composite film, resulting in a decrease in the mechanical properties of the gasket, which directly affects the heat seal strength and heat seal performance of the pharmaceutical packaging composite film.

[0112] Examples 19-24

[0113] Referring to the preparation method and parameter conditions of Example 17, the specific differences are shown in Table 4; the stretching ratio in Table 4 is the stretching ratio of the longitudinally stretched composite film for transverse stretching during the two-step bidirectional stretching of the screen film; the winding speed is the winding speed of the anti-fog stretched composite film after cutting during the cutting and winding process.

[0114] Comparative Example 17

[0115] The preparation method and parameter conditions of Example 17 were used with the exception that in the process of preparing the modified LLDPE functional layer, the molecular weight of the raw material linear low-density polyethylene was 5.0×10 2 g / mol.

[0116] Comparative Example 18

[0117] The preparation method and parameter conditions of Example 17 were used with the exception that in the process of preparing the modified LLDPE functional layer, the molecular weight of the raw material linear low-density polyethylene was 1.0×10 6 g / mol.

[0118] Comparative Example 19

[0119] The preparation method and parameter conditions are referred to in Example 17, except that the stretching ratio of the longitudinally stretched composite film to the transverse stretching is set to 5 times during the two-step bidirectional stretching process of the screen film.

[0120] Comparative Example 20

[0121] Refer to the preparation method and parameter conditions of Example 17, except that the winding speed of the anti-fog stretched composite film after cutting is 5m / min during the cutting and winding process.

[0122] Comparative Example 21

[0123] Refer to the preparation method and parameter conditions of Example 17, except that the winding speed of the cut anti-fog stretched composite film during the cutting and winding process is 50m / min.

[0124] Experimental Example 4 Heat Sealing Performance Test

[0125] Cut a 100mm×15mm sample and ensure that the sample has no defects and the edges are flat; condition the sample in an environment with a temperature of 23±2℃ and a relative humidity of 50±5% for 24 hours; use a heat seal tester to heat seal at a gradient temperature (120℃-160℃) and measure the lowest temperature (T 1 ) and the maximum temperature (T 2 ), heat sealing temperature window width ΔT = T 2 -T 1 ; The specific test results are shown in Table 4.

[0126] Table 4 Heat sealing performance test of Examples 19-24 and Comparative Examples 17-21

[0127]

[0128]

[0129] As shown in the heat-sealing temperature window width data of the pharmaceutical packaging composite film in Table 4, the heat-sealing temperature window width values ​​of the pharmaceutical packaging composite films of Examples 19-24 are stable within the range of 35-40°C, indicating that the pharmaceutical packaging composite films of Examples 19-24 have good heat-sealing properties. In contrast, in the process of preparing the modified LLDPE functional layer, the molecular weight of the added linear low-density polyethylene is too low, which leads to weak intermolecular forces, so that the melt can reach a thermal flow state at a relatively low temperature, and the thermal stability is relatively poor. The obtained modified LLDPE functional layer is prone to degradation and oxidation reactions during the heat-sealing process, resulting in the upper and lower limits of the heat-sealing temperature window of the pharmaceutical packaging composite film being reduced at the same time, and the heat-sealing temperature window width being narrowed; the high-molecular-weight linear low-density polyethylene requires a higher temperature and pressure to melt it, resulting in an increase in the difference in thermal expansion coefficients between the gasket and the inner cover, and generating interlayer stress under the heat-sealing temperature cycle, resulting in a narrowing of the heat-sealing temperature window width of the pharmaceutical packaging composite film. By adding linear low-density polyethylene with appropriate molecular weight, the heat sealing temperature window of the pharmaceutical packaging composite film can be expanded by lowering the initial hot air temperature, improving high temperature tolerance, optimizing molecular chain distribution and enhancing process compatibility. This not only improves the fault tolerance of the production process, but also ensures that the pharmaceutical packaging composite film has high heat sealing strength and sealing stability, thereby improving its heat sealing performance.

[0130] The difference of Comparative Example 19 is that the stretching ratio of the longitudinally stretched composite film to the transverse stretching is set to 5 times during the bidirectional two-step stretching process of the screen film; the increase of the transverse stretching ratio will intensify the orientation of the polymer chain, resulting in an increase in the crystallinity of the modified LLDPE functional layer material, and a decrease in the activity of its molecular chain, resulting in uneven thickness distribution of the pharmaceutical packaging composite film, and local thinning when its ductility reaches the limit. As a result, the thickness difference in the heat sealing area increases, which in turn affects the consistency of the heat sealing temperature and narrows the effective heat sealing temperature window.

[0131] In contrast, in Examples 20-21, if the winding speed of the anti-fog stretch composite film after cutting is too low or too high during the cutting and winding process, the heat sealing temperature window width of the composite film for pharmaceutical packaging will become narrower. The winding speed further stabilizes the heat sealing temperature window width of the composite film for pharmaceutical packaging by regulating the cooling rate, residual stress and interlayer bonding state of the composite film, so that it maintains good heat sealing performance under heat sealing conditions.

[0132] Although embodiments of the present invention have been shown and described, it will be appreciated by those skilled in the art that various changes, modifications, substitutions and variations may be made to the embodiments without departing from the principles and spirit of the present invention, and that the scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A process for preparing a composite film for drug packaging, characterized in that: The preparation process of the pharmaceutical packaging composite film is as follows: Pre-coating an interlayer adhesive between the outer cover, the inner cover and the gasket to obtain a pre-coated composite film; Performing hydrostatic treatment on the pre-coated composite membrane to obtain a composite membrane; The composite film is stretched longitudinally and transversely by two-step bidirectional stretching of the screen film, and then an anti-fog coating is applied to obtain an anti-fog stretched composite film; The anti-fog stretch composite film is cut and rolled up by adopting efficient cutting and rolling to obtain the pharmaceutical packaging composite film; The outer cover is a modified HDPE functional layer; the inner cover is a modified polypropylene functional layer; and the gasket is a modified LLDPE functional layer.

2. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The specific operation process of the hydrostatic treatment is as follows: insert the pre-coated composite film into the core tube of the hydraulic hose crimping machine; preheat the core tube to 70°C, and pre-press for 10-15s at 5-8MPa; perform gradient pressurization, with each level of pressurization interval being 5s, and each level of pressure being maintained for 10s; finally, perform precision pressing and shaping, with the mold temperature maintained at 40-50°C and hot pressing for 25s; cool to room temperature, and use a pneumatic ejection device to perform demolding to obtain the composite film.

3. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The modified HDPE functional layer is made of the following raw materials in parts by weight: 100 parts of high-density polyethylene, 1.5-2.0 parts of modified nano-silicon dioxide, 0.8-1.2 parts of nano-talc, 0.35-0.45 parts of polyisobutylene, 0.06 parts of hindered amine light stabilizer, and 0.03 parts of nucleating agent; The preparation method of the modified HDPE functional layer is as follows: premixing the high-density polyethylene with the modified nano-silicon dioxide and the nano-talc at 65° C. for 5 minutes; adding the liquid polyisobutylene and the hindered amine light stabilizer, and continuing to mix until uniform dispersion; finally adding the nucleating agent and mixing to obtain a melt-modified HDPE; transferring the melt-modified HDPE to a co-rotating twin-screw extruder to complete the melt extrusion process; controlling the contact pressure of the cooling roller to be 0.2-0.4 MPa; and obtaining the modified HDPE functional layer through corona treatment; the molecular weight of the high-density polyethylene is 1.0×10 5 -1.5×10 5 g / mol.

4. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The modified PP functional layer is made of the following raw materials in parts by weight: 100 parts of block copolymer PP particles, 8-12 parts of POE elastomer, 0.5-1.0 parts of SEBS elastomer, 0.2-0.5 parts of maleic anhydride grafted PP, 0.2 parts of lubricant, and 0.07 parts of nucleating agent; The preparation method of the modified PP functional layer is as follows: drying the block copolymer PP particles in a drying oven at 80° C. for 4 hours, preheating the POE elastomer and the SEBS elastomer at 60° C. for 30 minutes, adding them together into a high-speed mixer at 55° C., and mixing until they are uniformly dispersed; adding the maleic anhydride grafted PP and the nucleating agent, and continuing to mix at a speed of 500-600 rpm for 2 minutes; finally adding the lubricant and mixing to obtain melt-modified PP; The melt-modified PP is melt-extruded in a co-rotating twin-screw extruder to obtain the modified PP functional layer under the action of a cooling roller; the molecular weight of the block copolymer PP particles is 2.0×10 5 g / mol.

5. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The modified LLDPE functional layer is made of the following raw materials in parts by weight: 75-80 parts of linear low-density polyethylene, 18 parts of ethylene-acrylic acid copolymer, 5-8 parts of ethylene-vinyl acetate copolymer, 2-3 parts of modified nano-kaolin, and 0.06 parts of antioxidant; The preparation method of the modified LLDPE functional layer is as follows: adding the dried linear low-density polyethylene, the ethylene-acrylic acid copolymer, the ethylene-vinyl acetate copolymer and the modified nano-kaolin to the main feed port of the extruder; adding the antioxidant at the second zone position through a side feeder, performing a melt mixing process, and forming a uniform modified LLDPE film; performing corona treatment with a high-voltage generator with a power of 5-7kW to obtain the modified LLDPE functional layer; the antioxidant is obtained by compounding antioxidant 1076 and antioxidant 168 in a proportion of 1:1; the molecular weight of the linear low-density polyethylene is 4.0×10 4 -6.0×10 4 g / mol.

6. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The specific operation process of the bidirectional two-step stretching of the screen film is as follows: preheating the composite film to 80°C, using a multi-roller longitudinal stretching unit, setting the stretching ratio to 3.0 times at 95°C and a stretching speed of 12-15m / min, and longitudinally stretching the composite film; cooling to quickly shape the longitudinally stretched composite film; preheating the longitudinally stretched composite film to 110°C, setting the stretching ratio to 3.3-3.5 times, and transversely stretching at 125°C; then heat setting; after the heat setting is completed, cooling to room temperature to obtain a stretched composite film; coating a 0.2μm anti-fog coating on the upper surface of the stretched composite film to obtain the anti-fog stretched composite film.

7. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The specific operation process of cutting and winding is as follows: the unwinding shaft releases the anti-fog stretch composite film at a constant tension of 80N / m, and performs laser precision cutting at a power of 250W; nitrogen is simultaneously purged at a pressure of 0.5MPa; the winding speed is controlled to be 25-30m / min to wind up the anti-fog stretch composite film after cutting to obtain the pharmaceutical packaging composite film.

8. The process for preparing a composite film for pharmaceutical packaging according to claim 1, characterized in that: The interlayer adhesive is a two-component polyurethane adhesive; the coating amount of the two-component polyurethane adhesive between the outer cover and the inner cover is 3.0 g / m 2 The coating amount between the inner cover and the gasket is 2.5g / m 2 .

9. A composite film for pharmaceutical packaging, characterized in that: The pharmaceutical packaging composite film is prepared by the preparation method described in any one of claims 1 to 8; the pharmaceutical packaging composite film consists of three parts: an outer cover, an inner cover and a gasket; the outer cover is a modified HDPE functional layer with a thickness of 1.0 mm; the inner cover is a modified polypropylene functional layer with a thickness of 0.6 mm; the gasket is a modified LLDPE functional layer with a thickness of 0.9 mm.

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