Polyolefin co-extruded film for liquid-liquid multi-chamber infusion bag and preparation method and application thereof

Abstract

The application provides a polyolefin co-extrusion film for a liquid-liquid multi-chamber infusion bag and a preparation method and application thereof, and relates to the technical field of infusion packaging materials. The polyolefin co-extrusion film for the liquid-liquid multi-chamber infusion bag comprises a heat-sealing layer, an outer surface layer and an intermediate layer. The heat-sealing layer comprises random copolymerized polypropylene, terpolymerized polypropylene, ethylene-alpha olefin copolymer and styrene block copolymer. The outer surface layer comprises polypropylene and styrene block copolymer. The intermediate layer comprises polypropylene and styrene block copolymer. The polyolefin co-extrusion film realizes virtual welding through a two-step method, has stable heat-sealing strength, prevents accidental opening of the virtual welding strip of the infusion bag, and ensures smooth connection of the chambers by extruding the virtual welding strip to open the virtual welding strip during clinical use.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of infusion packaging materials, in particular to a polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags and a preparation method thereof. BACKGROUND

[0002] Multi-chamber bag infusion products include powder-liquid multi-chamber bags and liquid-liquid multi-chamber bags. The bag body is divided into multiple independent chambers by virtual welding, and different medicinal liquids or powders are placed in different chambers. During clinical use, medical staff can make the chambers communicate by extrusion, and the mixed medicine can be injected intravenously into patients. Multi-chamber bags have many advantages, such as closed system dispensing, avoiding microbial contamination; ready-to-use, portable operation, shortening the dispensing time; pre-dispensing the amount of medicine, avoiding medical accidents caused by dispensing errors.

[0003] The key technology of multi-chamber bags is to divide the bag body into independent chambers by using a virtual welding strip structure. Before the use of the medicine, the virtual welding strip is used to isolate different medicines, and during use, the virtual welding strip can be smoothly opened to make the chambers communicate and mix the medicine. The heat sealing strength is a key indicator for evaluating the virtual welding strip. On the one hand, in order to prevent the virtual welding strip from being accidentally opened, the heat sealing strength of the virtual welding strip cannot be too low; on the other hand, the heat sealing strength cannot be too high to ensure that it can be smoothly opened during clinical use, and the general requirement is 5-15 N / 15 mm. The virtual welding strip heat sealing strength of 5-10 N / 15 mm is more suitable for powder-liquid double-chamber bags, and for large-size liquid-liquid multi-chamber bags, the virtual welding strip heat sealing strength needs to withstand greater impact, and the virtual welding strip heat sealing strength is preferably 10-15 N / 15 mm. The existing virtual welding strip technology adopts a one-step heat welding process: the upper and lower molds are pressed together after heating, and the heat of the upper and lower molds is transferred to the inner layer, and the polymer molecules of the inner layer are melted and bonded. For one-step heat welding process, it is easy to form a virtual welding strip with a heat sealing strength of 5-10 N / 15 mm, and when the heat sealing strength is 10-15 N / 15 mm, because the virtual welding strip of the film material has a narrow welding temperature window, the welding is unstable, and slight fluctuations in welding conditions (temperature, pressure, time) will cause the heat sealing strength of the virtual welding strip to exceed the range. In addition, heat welding is not a closed environment, and the heat energy transferred to the film material during welding is also easily affected by the environment and changes, thereby causing the heat sealing strength of the virtual welding strip to exceed the range. SUMMARY

[0004] The purpose of the present application is to provide a polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags and a preparation method thereof, which can realize virtual welding and real welding, has stable virtual welding strip heat sealing strength, and good low-temperature impact resistance.

[0005] Another purpose of the present application is to provide an application of a polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags.

[0006] Another object of the present application is to provide a liquid-liquid multi-chamber infusion bag prepared using the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag.

[0007] The present application is achieved by the following technical solutions:

[0008] In a first aspect, the present application provides a polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag, comprising a heat-sealing layer, an outer layer and an intermediate layer. The heat-sealing layer comprises, by weight fraction, 30-40 parts of random copolymerized polypropylene, 20-30 parts of terpolymerized polypropylene, 5-15 parts of ethylene-α-olefin copolymer and 15-25 parts of styrene block copolymer. The outer layer comprises, by weight fraction, 80-95 parts of polypropylene and 5-20 parts of styrene block copolymer. The intermediate layer comprises, by weight fraction, 40-60 parts of polypropylene and 40-60 parts of styrene block copolymer.

[0009] Further, the melting point of the terpolymerized polypropylene is 125-135℃, the melting point of the random copolymerized polypropylene is 140-160℃, and the melting point of the ethylene-α-olefin copolymer is 60-110℃.

[0010] Further, the terpolymerized polypropylene is propylene-ethylene-butene copolymer, the random copolymerized polypropylene is propylene-ethylene copolymer, the comonomer of the ethylene-α-olefin copolymer is butene, hexene or octene, and the styrene block copolymer is styrene-ethylene-ethylene-styrene block copolymer or styrene-ethylene-butene-styrene block copolymer.

[0011] In a second aspect, the present application provides a preparation method of the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag, comprising the following steps: the heat-sealing layer, the outer layer and the intermediate layer are respectively melt-plasticized by an extruder, then enter a multi-layer film blowing die, the film blowing die blows down to form a film bubble, then the film bubble is cooled by purified water, the film bubble is shaped by a herringbone plate, then is pulled by a pulling roller, and finally is wound by a winding roller to obtain the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag.

[0012] In a third aspect, the present application provides an application of the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag in preparing a liquid-liquid multi-chamber infusion bag.

[0013] In a fourth aspect, the present application provides a liquid-liquid multi-chamber infusion bag prepared using the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag.

[0014] Further, the preparation method of the liquid-liquid multi-chamber infusion bag comprises the following steps:

[0015] S1, initial welding: two pieces of the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bag are initially welded to form a virtual welding strip, and the virtual welding strip has a heat sealing strength of 5-8 N / 15 mm;

[0016] S2, bag making: the co-extrusion film with virtual welding strip obtained in S1 is hot pressure welded to form a real welding strip, and the hot sealing strength of the real welding strip is 30-45 N / 15mm;

[0017] S3, the liquid-liquid multi-chamber infusion bag obtained in S2 is subjected to moist heat sterilization to obtain a virtual welding strip with a hot sealing strength of 10-15 N / 15mm.

[0018] After the bag making is completed, it also includes completing the tube welding, pouring the liquid medicine, and inserting the infusion plug.

[0019] In the present application, in step S1, the welding pressure of the initial welding is 0.4-0.6 MPa, the welding time is 0.4-0.8 s, and the welding temperature is 100-122℃.

[0020] In the present application, in step S2, the hot pressure welding pressure is 0.4-0.6 MPa, the welding time is 0.5-1 s, and the welding temperature is 140-150℃; in step S3, the moist heat sterilization temperature is 120-125℃, and the sterilization time is 10-15 min.

[0021] In the present application, the width of the virtual welding strip is 2-5mm, and the width of the real welding strip is 1-4mm.

[0022] Random copolymer polypropylene is prepared by simultaneously polymerizing ethylene molecules and propylene molecules. Since the ethylene molecules randomly inserted into the main chain of the polymer hinder the crystalline arrangement of the polymer molecules, the random copolymer polypropylene has a lower melting temperature and higher impact resistance. The chemical structure of ethylene-α-olefin copolymer contains random copolymer sequences, and the presence of such random copolymer sequences makes the chain structure of the material more loose and the molecular weight distribution more dispersed, so that the ethylene-α-olefin copolymer has good flexibility, tensile property and heat resistance. Ternary copolymer polypropylene introduces ethylene and butene into the polypropylene molecular chain, which destroys the regularity of the polypropylene molecular chain, reduces the crystallization temperature, makes the ternary copolymer polypropylene have low heat sealing initial temperature, high heat sealing strength, and wide heat sealing window.

[0023] The ethylene-alpha olefin copolymer has the lowest melting point, can melt, move and entangle at a lower temperature, can realize initial welding of the pseudo-welding strip at a low temperature, and has high melt strength and flexibility, so as to ensure the low-temperature impact performance of the pseudo-welding strip and the real welding strip. The melting point of the terpolymer polypropylene is close to the moist heat sterilization temperature, so that the molecular chain can melt, move and entangle during the moist heat sterilization process, thereby further improving the heat sealing strength of the pseudo-welding strip. The random copolymer polypropylene with high melting point can melt, move and entangle under high-temperature conditions, so as to form the real welding strip. The molecular chains of the polymers cross and interweave at different temperatures, so that the polymer molecular chains have a certain spatial structure and the intermolecular interaction force is increased, which can increase the viscosity of the material and improve the mechanical strength of the material, and can also convert the chain rupture into pulling out and stretching of the long chain, thereby improving the toughness of the material. By using the different degrees of entanglement of the components at different temperatures, the entanglement density can be reasonably controlled, the influence of the excessive entanglement density on the forming and processing of the material is avoided, and the strength and toughness of the material are prevented from being reduced due to the excessive entanglement. The three high-molecular materials with different melting points are added to the heat sealing layer, so that the welding temperature range of the film material is wider, and the specific component allocation ratio can realize the stable heat sealing strength of the pseudo-welding strip and the low-temperature impact performance of the film material at the same time.

[0024] The random copolymer polypropylene, the terpolymer polypropylene and the ethylene-alpha olefin copolymer have different melting points, can melt, move and entangle under different temperature conditions, so as to form the pseudo-welding strip and the real welding strip with different heat sealing strengths. The first step of forming the pseudo-welding strip is initial welding at a low welding temperature, at this time, the molecular chains of the ethylene-alpha olefin copolymer and part of the terpolymer polypropylene melt, move and entangle, so as to form the pseudo-welding strip with lower and stable heat sealing strength (5-8 N / 15 mm). The pseudo-welding strip is strengthened by the moist heat sterilization, in this process, the pseudo-welding strip is subjected to the constant sterilization temperature and the long sterilization process, and the molecular chains of the terpolymer polypropylene melt, move and entangle, so as to form the pseudo-welding strip with higher heat sealing strength (10-15 N / 15 mm). Under the condition of higher real welding temperature, the random copolymer polypropylene, the terpolymer polypropylene and the ethylene-alpha olefin copolymer all participate in the molecular chain melting, movement and entanglement, so as to obtain the real welding strip with high heat sealing strength (30-45 N / 15 mm).

[0025] The technical scheme of the present application has at least the following advantages and beneficial effects:

[0026] 1. Using random copolymer polypropylene, terpolymer polypropylene and ethylene-α-olefin copolymer with different melting points as heat sealing materials and carrying out virtual welding through a two-step method, each component can realize gradual melting, movement and entanglement during the welding process, the melt strength is improved, the melt is not easy to break during the welding process, the toughness of the infusion bag is enhanced; meanwhile, the welding temperature window can be widened, the stability and uniformity of the virtual welding strip heat sealing strength are improved, and the quality of the infusion bag is improved.

[0027] 2. By realizing the initial welding of the virtual welding strip under low temperature conditions, the initial welding temperature is prevented from being too high to cause the molecular chain of the polyolefin co-extruded film to break, the precipitation of insoluble particles is reduced, and the safety of the infusion bag is ensured.

[0028] 3. The middle layer uses polypropylene and polyethylene block copolymer as the main material, which can improve the strength, toughness and barrier property of the polyolefin co-extruded film. The outer surface layer uses polypropylene as the main material, which can improve the mechanical strength of the polyolefin co-extruded film and also provide good printing performance.

[0029] 4. The glass transition temperature of the styrene block copolymer is low, which can improve the low temperature impact resistance of the material and maintain the low temperature performance of the film material. The styrene block copolymer has good processing performance, which makes the polyolefin co-extruded film and the infusion bag more easily formed and processed during the production process, while maintaining the stability and durability of the film material and the infusion bag. BRIEF DESCRIPTION OF DRAWINGS

[0030] Figure 1 The heat sealing strength and welding temperature change curve of Example 1;

[0031] Figure 2 The heat sealing strength and welding temperature change curve of Example 2;

[0032] Figure 3 The heat sealing strength and welding temperature change curve of Comparative Example 1;

[0033] Figure 4 The heat sealing strength and welding temperature change curve of Comparative Example 2;

[0034] Figure 5 The heat sealing strength and welding temperature change curve of Comparative Example 3. DETAILED DESCRIPTION

[0035] The present application will be further described in conjunction with specific embodiments, but the embodiments do not limit the present application in any form. Unless otherwise specified, the raw materials used in the embodiments of the present application are conventional commercially available raw materials.

[0036] Example 1

[0037] Preparation of the polyolefin co-extrusion film for the liquid-liquid multi-chamber infusion bag: the heat-sealing layer, the outer surface layer and the intermediate layer are respectively melt-plasticized by the extruder, then enter the multi-layer film blowing die, the film bubble is formed by the downward blowing of the film blowing die, then cooled by purified water, the film bubble is shaped by the herringbone plate, then pulled by the traction roller, finally wound by the winding roller.

[0038] The heat-sealing layer comprises random copolymerized polypropylene (propylene-ethylene copolymer), terpolymerized polypropylene (propylene-ethylene-butylene copolymer), ethylene-alpha olefin copolymer (the comonomer is hexene) and styrene block copolymer; the outer surface layer comprises polypropylene and styrene block copolymer; the intermediate layer comprises polypropylene and styrene block copolymer. The styrene block copolymer is styrene-ethylene-butylene-styrene block copolymer.

[0039] The melting point of the propylene-ethylene-butylene copolymer is 130℃, the melting point of the propylene-ethylene copolymer is 150℃, and the melting point of the ethylene-alpha olefin copolymer (the comonomer is hexene) is 80℃.

[0040] The preparation method of the liquid-liquid multi-chamber infusion bag comprises the following steps:

[0041] S1, initial welding of the virtual welding: two pieces of the liquid-liquid multi-chamber infusion bag are initially welded by the polyolefin co-extrusion film, the welding pressure of the initial welding is 0.5MPa, the welding time is 0.6s, the virtual welding strip is formed, and the width of the virtual welding strip is 4mm;

[0042] S2, bag making: the co-extrusion film with the virtual welding strip obtained in S1 is hot-press welded, the hot-press welding pressure is 0.6MPa, the welding time is 0.8s, the welding temperature is 145℃, the real welding strip is formed, and the width of the real welding strip is 2mm;

[0043] S3, the liquid-liquid multi-chamber infusion bag obtained in S2 is subjected to moist heat sterilization, the moist heat sterilization temperature is 120℃, the sterilization time is 12min, and the heat sealing strength of the virtual welding strip is further improved.

[0044] Example 2

[0045] Preparation of the polyolefin co-extrusion film for the liquid-liquid multi-chamber infusion bag: the heat-sealing layer, the outer surface layer and the intermediate layer are respectively melt-plasticized by the extruder, then enter the multi-layer film blowing die, the film bubble is formed by the downward blowing of the film blowing die, then cooled by purified water, the film bubble is shaped by the herringbone plate, then pulled by the traction roller, finally wound by the winding roller.

[0046] The heat-seal layer comprises random copolymerized polypropylene (propylene-ethylene copolymer), terpolymerized polypropylene (propylene-ethylene-butylene copolymer), ethylene-alpha olefin copolymer (comonomer is butene), and styrene block copolymer; the outer layer comprises polypropylene and styrene block copolymer; and the intermediate layer comprises polypropylene and styrene block copolymer. The styrene block copolymer is styrene-ethylene-ethylene-styrene block copolymer.

[0047] The melting point of the propylene-ethylene-butylene copolymer is 125 DEG C, the melting point of the propylene-ethylene copolymer is 140 DEG C, and the melting point of the ethylene-alpha olefin copolymer (comonomer is butene) is 60 DEG C.

[0048] The preparation method of the liquid-liquid multi-chamber infusion bag comprises the following steps:

[0049] S1, virtual welding initial welding: two pieces of liquid-liquid multi-chamber infusion bags are initially welded by polyolefin co-extrusion film, the welding pressure of the initial welding is 0.4 MPa, the welding time is 0.8 s, a virtual welding strip is formed, and the width of the virtual welding strip is 2 mm;

[0050] S2, bag making: the co-extrusion film with the virtual welding strip obtained in S1 is heat pressure welded, the heat pressure welding pressure is 0.6 MPa, the welding time is 0.5 s, the welding temperature is 150 DEG C, a real welding strip is formed, and the width of the real welding strip is 4 mm;

[0051] S3, the liquid-liquid multi-chamber infusion bag obtained in S2 is subjected to moist heat sterilization, the moist heat sterilization temperature is 125 DEG C, and the sterilization time is 10 min.

[0052] Example 3

[0053] The difference between the embodiment and example 1 is that the melting point of the propylene-ethylene-butylene copolymer is 135 DEG C, the melting point of the propylene-ethylene copolymer is 160 DEG C, and the melting point of the ethylene-alpha olefin copolymer (comonomer is octene) is 110 DEG C.

[0054] Example 4

[0055] The difference between the embodiment and example 1 is that the intermediate layer of the polyolefin co-extrusion film for the liquid-liquid multi-chamber infusion bag comprises 60% of polypropylene and 40% of styrene block copolymer in terms of weight percentage.

[0056] Example 5

[0057] The difference between the embodiment and example 1 is that the intermediate layer of the polyolefin co-extrusion film for the liquid-liquid multi-chamber infusion bag comprises 50% of polypropylene and 50% of styrene block copolymer in terms of weight percentage.

[0058] Example 6

[0059] The difference between this example and Example 1 is that the outer skin layer of the polyolefin coextruded film for a liquid-liquid multi-chamber infusion bag comprises, by weight percentage, polypropylene 80% and styrene block copolymer 20%.

[0060] Example 7

[0061] The difference between this example and Example 1 is that the outer skin layer of the polyolefin coextruded film for a liquid-liquid multi-chamber infusion bag comprises, by weight percentage, polypropylene 95% and styrene block copolymer 5%.

[0062] Comparative Example 1

[0063] In this comparative example, the heat-seal layer comprises random copolymerized polypropylene (propylene-ethylene copolymer), terpolymerized polypropylene (propylene-ethylene-butene copolymer) and styrene block copolymer. The rest is the same as Example 1.

[0064] Comparative Example 2

[0065] In this comparative example, the heat-seal layer comprises random copolymerized polypropylene (propylene-ethylene copolymer), ethylene-α-olefin copolymer (comonomer is hexene) and styrene block copolymer. The rest is the same as Example 1.

[0066] Comparative Example 3

[0067] In this comparative example, the heat-seal layer comprises random copolymerized polypropylene (propylene-ethylene copolymer) and styrene block copolymer. The rest is the same as Example 1.

[0068] The polyolefin coextruded film formula for a liquid-liquid multi-chamber infusion bag of Comparative Examples 1-3 and Example 1-2, each component of the middle layer, the outer skin layer and the heat-seal layer is allocated as follows, based on 100% of each layer:

[0069] Table 1

[0070]

[0071] The polyolefin coextruded film prepared in the above comparative examples is welded at different welding temperatures using the same welding pressure and welding time as Example 1. Ten welding strips of the same coextruded film are welded under one welding temperature condition, and the welding strips are cut into a width of 15 mm. Five of them are tested for heat-seal strength to obtain the heat-seal strength before sterilization, and five welding strips are subjected to moist heat sterilization, and then tested for heat-seal strength to obtain the heat-seal strength after sterilization. The average heat-seal strength of the welding strips before and after sterilization is recorded as follows:

[0072] Table 2

[0073]

[0074] According to Table 2 and Figures 1-5It can be seen that, in order to make the heat sealing strength of the sterilized hot bar 10-15 N / 15 mm, the initial welding temperature of the comparative examples needs to be controlled in a narrow range (less than 3℃). The initial welding temperature of the examples is in the range of 100-122℃, and the hot bar with a heat sealing strength of 5-10 N / 15 mm can be formed. After the wet heat sterilization, the heat sealing strength of the hot bar is increased to 10-15 N / 15 mm. The hot bar of the polyolefin co-extrusion film prepared by the application has a wide welding window, and the production process is easier to control.

[0075] The heat sealing strength of the hot bar of the polyolefin co-extrusion films of examples 3-7 before and after sterilization was detected. The results show that the heat sealing strength of the hot bar of examples 3-7 before and after sterilization is not much different from that of example 1, indicating that the hot bar has a wide welding window and high heat sealing strength under the conditions of examples 3-7.

[0076] The quality of the hot bar (including the size and uniformity of the heat sealing strength) will affect the performance of the liquid-liquid multi-chamber soft bag: if the heat sealing strength is too low, the hot bar will be accidentally opened when the soft bag falls, and if the heat sealing strength is too high, the bag will be difficult to open during clinical use. Therefore, the quality of the hot bar of the infusion bag needs to be tested, and the test method is as follows:

[0077] Liquid-liquid multi-chamber infusion bags were prepared according to Table 1. The hot bar preparation processes of comparative examples 1-3 and examples 1-2 are different, and the hot bar preparation processes are consistent. Specifically, the hot bar of comparative examples 1-3 is welded at the welding temperature of the hot bar when the heat sealing strength of the sterilized hot bar is 13 N / 15 mm, and does not undergo wet heat sterilization; the hot bar of examples 1-2 is welded at 110℃, and after wet heat sterilization, the preparation of the liquid-liquid multi-chamber infusion soft bag is completed. After being packed according to the standard packing method, it is placed for 7 days.

[0078] Hot bar heat sealing strength test: randomly take 20 liquid-liquid multi-chamber infusion soft bags, cut a sample with a width of 15 mm and a length of 100 mm at the middle position of the hot bar, and test it with a universal testing machine according to the heat sealing strength test method (YBB00122003-2015).

[0079] Whole box drop test: drop the whole box of liquid-liquid multi-chamber infusion soft bags from a height of 2.8 meters to a hard ground, and open the box to check whether the hot bar is opened.

[0080] Clinical simulation opening test: roll the liquid-liquid multi-chamber infusion soft bag from the tail with both hands. As the rolling, the liquid storage space decreases, and the pressure in the bag increases, until the hot bar is connected and opened.

[0081] Insoluble particles: after manually opening the hot bar, the liquid is mixed, and the insoluble particles are measured according to the packaging material insoluble particle determination method (YBB00272004-2015). The number of particles of 5 μm and above per 1 ml is counted.

[0082] Table 3

[0083]

[0084] From Table 3, it can be seen that the welding temperature of the comparative dummy welding rod is higher than 120 DEG C. The welding temperature of the dummy welding rod of the embodiment is lower and the welding temperature window is wider, which is beneficial to quality control and less energy consumption.

[0085] The standard deviation of the hot strength of the comparative dummy welding rod is large, indicating that the hot strength fluctuates greatly. The standard deviation of the embodiment is small, indicating that the hot strength is more stable.

[0086] The weak welding rod of the comparative example opens after falling, because the minimum hot strength of the dummy welding rod is small, the impact resistance of the dummy welding rod is poor, and accidental opening is easy to occur.

[0087] The hot strength of the dummy welding rod of the embodiment is uniform and stable, so the manual opening is more smooth, and the clinical use experience is good.

[0088] The number of insoluble particles of the embodiment is lower, because the welding temperature of the comparative dummy welding rod is high, which may cause the molecules in the polyolefin co-extrusion film to be easy to break, and to be precipitated into the liquid medicine, so the number of insoluble particles is high. It shows that the infusion bag prepared by the embodiment is safer for patients.

[0089] The above is only the preferred embodiment of the present application, and is not used to limit the present application. For those skilled in the art, the present application can have various modifications and changes. Any modification, equivalent replacement, improvement, etc. within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. A polyolefin co-extruded film for liquid-liquid multi-chamber infusion bags, characterized by: The heat-sealing layer comprises, by weight fraction, 30-40 parts of random copolymerized polypropylene, 20-30 parts of terpolymerized polypropylene, 5-15 parts of ethylene-alpha olefin copolymer and 15-25 parts of styrene block copolymer; the outer surface layer comprises, by weight fraction, 80-95 parts of polypropylene and 5-20 parts of styrene block copolymer; The intermediate layer comprises, by weight fraction, 40-60 parts of polypropylene and 40-60 parts of styrene block copolymer.

2. The polyolefin co-extruded film for liquid-liquid multi-chamber infusion bag according to claim 1, characterized by: The melting point of the terpolymerized polypropylene is 125-135℃, the melting point of the random copolymerized polypropylene is 140-160℃, and the melting point of the ethylene-alpha olefin copolymer is 60-110℃.

3. The polyolefin co-extruded film for liquid-liquid multi-chamber infusion bag according to claim 2, characterized in that: The terpolymerized polypropylene is propylene-ethylene-butene copolymer, the random copolymerized polypropylene is propylene-ethylene copolymer, the ethylene-alpha olefin copolymer has butene, hexene or octene as comonomer, and the styrene block copolymer is styrene-ethylene-ethylene-styrene block copolymer or styrene-ethylene-butene-styrene block copolymer.

4. The method of producing a polyolefin co-extruded film for a liquid-liquid multi-chamber infusion bag according to any one of claims 1 to 3, characterized in that, The method comprises the following steps: The heat-sealing layer, the outer surface layer and the intermediate layer are respectively melt-plasticized by extruders, then enter a multi-layer film blowing die, a film bubble is formed by downward blowing of the film blowing die, then the film bubble is cooled by purified water, and then the film bubble is shaped by a herringbone plate, drawn by a traction roller and finally wound by a winding roller to obtain the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags.

5. Use of the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags according to any one of claims 1-3 in the preparation of liquid-liquid multi-chamber infusion bags.

6. A liquid-liquid multi-chambered infusion bag, characterized by: The liquid-liquid multi-chamber infusion bag is prepared by using the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags according to any one of claims 1-3, and the preparation method of the liquid-liquid multi-chamber infusion bag comprises the following steps: S1, virtual welding initial welding: two pieces of the polyolefin co-extrusion film for liquid-liquid multi-chamber infusion bags are initially welded to form a virtual welding strip, the welding pressure of the initial welding is 0.4-0.6 MPa, the welding time is 0.4-0.8 s, the welding temperature is 100-122℃, and the hot sealing strength of the virtual welding strip is 5-8 N / 15 mm; S2, bag making: the co-extrusion film with the virtual welding strip obtained in S1 is hot-press welded to form a real welding strip, and the hot sealing strength of the real welding strip is 30-45 N / 15 mm; S3, the liquid-liquid multi-chamber infusion bag obtained in S2 is subjected to moist heat sterilization to obtain a virtual welding strip with a hot sealing strength of 10-15 N / 15 mm.

7. The liquid-liquid multi-chamber infusion bag of claim 6, wherein: In step S2, the hot-press welding pressure is 0.4-0.6 MPa, the welding time is 0.5-1 s, and the welding temperature is 140-150℃; in step S3, the moist heat sterilization temperature is 120-125℃, and the sterilization time is 10-15 min.

8. The liquid-liquid multi-chamber infusion bag of claim 7, wherein: The width of the virtual welding strip is 2-5 mm, and the width of the real welding strip is 1-4 mm.

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