Multi-layer co-extruded polymer film, preparation method thereof, bag body and application of multi-layer co-extruded polymer film and preparation method thereof

Abstract

The invention relates to the technical field of co-extruded films, and provides a multi-layer co-extruded polymer film and a preparation method thereof, a bag body and application thereof, the multi-layer co-extruded polymer film comprises an outer surface layer, an inner surface layer and a middle layer, the inner surface layer comprises a flexible copolymer and a cycloolefin copolymer, the flexible copolymer comprises an ethylene-vinyl ester polymer, and the cycloolefin copolymer comprises a cycloolefin copolymer. The glass transition temperature Tg of the cycloolefin copolymer is not lower than 60 DEG C, the glass transition temperature Tg and the melting point mp of the flexible copolymer meet the relational expression that Tg is larger than or equal to mp, and in the inner surface layer of the multi-layer co-extrusion polymer film, the total mass content of the anti-blocking agent with the molecular weight being smaller than 500 g / mol and the inorganic matter anti-blocking agent is lower than 100 ppm. The multi-layer co-extrusion polymer film can be used for manufacturing a biological feed liquid bag, so that the inner side of the bag body is basically not crosslinked under an irradiation condition, and small molecular substances are basically not leaked out in the use process.

Description

Technical Field

[0001] The present invention relates to the technical field of co-extruded films, and specifically to a multi-layer co-extruded polymer film, a method for preparing the multi-layer co-extruded polymer film, a bag body, and the use of the multi-layer co-extruded polymer film or the bag body in the preparation of biological liquid bags, and the use of cycloolefin copolymers in the preparation of polymer films containing flexible copolymers. Background Art

[0002] Multilayer co-extruded polymer film is a barrier material with at least three layers of materials, including at least one barrier layer (generally EVOH or PA), an outer layer and an inner layer. The polymer film prepared with flexible copolymers (such as EVA, etc.) as raw materials is a commonly used inner layer film with good stability.

[0003] Multilayer co-extruded polymer films are commonly used in the manufacture of biomaterial fluid bags. Because the materials in biomaterial fluid bags are typically rich in nutrients and susceptible to microbial contamination, they often require irradiation sterilization before use. The flexible copolymer in the inner layer undergoes irradiation sterilization, which can lead to crosslinking, making it difficult to separate the layers. This is particularly true within the bag itself. After irradiation sterilization, the inner layers can adhere to each other due to crosslinking, resulting in adhesion inside the bag, making it impossible to separate and hindering its use.

[0004] Furthermore, since downstream products of biological fluids (such as pharmaceuticals) require high purity, if conventional opening agents are used to alleviate the adhesion of flexible copolymers, these opening agents, due to their small molecular weight, are easily diffused into the fluid, affecting the purity of the product. During the irradiation sterilization process, flexible copolymers are prone to degradation and re-crosslinking, and the small molecules produced by their degradation can also adversely affect the purity of downstream products. Therefore, there is an urgent need to develop a multilayer co-extruded polymer film that can be used to make biological fluid bags, so that the inner side of the bag is basically non-crosslinked under irradiation conditions and basically no small molecules are leaked during use. Summary of the Invention

[0005] The purpose of the present invention is to overcome the above-mentioned problems existing in the prior art and provide a multi-layer co-extruded polymer film and its preparation method, bag body and their applications. The multi-layer co-extruded polymer film can be used to make biological liquid bags, and the multi-layer co-extruded polymer film can be used to make biological liquid bags, so that the inner side of the bag body is basically not cross-linked and basically no small molecule substances leak out.

[0006] To achieve the above object, the present application provides a multi-layer co-extruded polymer film, characterized in that the multi-layer co-extruded polymer film comprises an outer surface layer, an inner surface layer and an intermediate layer, the inner surface layer comprises a flexible copolymer and a cyclic olefin copolymer, the flexible copolymer comprises an ethylene-vinyl ester polymer, the cyclic olefin copolymer has a glass transition temperature Tg not lower than 60℃, and the relationship between the melting point mp of the flexible copolymer and the glass transition temperature Tg of the cyclic olefin copolymer satisfies the relationship Tg≥mp,

[0007] and the total mass content of the openers with a molecular weight of 500g / mol or less and the inorganic openers in the inner surface layer of the multi-layer co-extruded polymer film is lower than 100ppm.

[0008] As a further improvement of the present application, Tg-mp≥5℃.

[0009] In the present application, the inner surface layer is doped with the cyclic olefin copolymer, and under the condition of synergistically controlling Tg≥mp (preferably Tg-mp≥5℃), during the cooling process after extrusion molding, the cyclic olefin copolymer can be cooled first to form a glassy structure, and a small amount of microcrystalline structure is formed on the surface of the film, that is, there is sufficient time for the crystals formed by the COC to form on the surface, which can better separate the inner surface layer and its adjacent layer, and also prevent the flexible copolymer of the inner surface layer from crosslinking together after dissociation and crosslinking after irradiation sterilization, while also reducing the pollution of the material liquid caused by the migration of small molecules generated by the chain rupture of the flexible copolymer. Moreover, compared with small molecule openers such as silicon dioxide and talc, the olefin-cyclic olefin copolymer is not easy to dissolve out, reducing the dissolution of substances during the use of the prepared biological material liquid bag, improving the reliability of the product, and alleviating or even avoiding the influence of small molecule exudates on the biological material liquid.

[0010] As a further improvement of the present application, the mass percentage of the cyclic olefin copolymer in the inner surface layer is 10-40%. In this case, it is beneficial to further improve the stability of the inner surface layer, reduce the degree of cracking of the flexible copolymer during irradiation sterilization, and reduce the dissolution of small molecules during the use of the bag.

[0011] As a further improvement of the present application, the relationship between the mass percentage W of the cyclic olefin copolymer in the inner surface layer and the value of Tg-mp satisfies the relationship 1≤W*(Tg-mp)≤15. The larger the value of Tg-mp, the better the crystallization level of the cyclic olefin copolymer, and the more likely it is to form crystals protruding from the surface on the surface, so as to improve its separability. That is, under the condition of increasing the value of Tg-mp, W can be reduced. It is found in the research process that when the mass percentage of the cyclic olefin copolymer is 10-40% and satisfies the relationship W*(Tg-mp), it is beneficial to improve the stability of the inner surface layer, reduce the degree of cracking of the flexible copolymer during irradiation sterilization, and reduce the dissolution of small molecules during the use of the bag.

[0012] As a further improvement of the present invention, the flexible copolymer comprises at least one of ethylene-vinyl acetate copolymer (EVA), ethylene-vinyl propionate copolymer, and ethylene-vinyl butyrate copolymer; preferably, the ethylene-vinyl ester polymer contains 9-28 mol% vinyl ester units; and preferably, the flexible copolymer has a Shore A hardness of 60-90 HA. Preferably, the inner surface layer has sufficient hardness to improve the barrier properties of the film, alleviate or prevent film curling, and balance the film's flexibility and rigidity, thereby preventing damage to bags made from the film due to folding during use.

[0013] As a further improvement of the present invention, the flexible copolymer is ethylene-vinyl acetate copolymer.

[0014] As a further improvement of the present invention, the cyclic olefin copolymer is a copolymer of norbornene and ethylene. The density of the cyclic olefin copolymer is generally 1.01-1.06 g / cm 3 .

[0015] As a further improvement of the present invention, the intermediate layer comprises at least one barrier layer and at least one flexible layer. The barrier layer comprises ethylene vinyl alcohol copolymer (EVOH) and / or polyamide (PA), and the flexible layer comprises a flexible copolymer. The type of the flexible copolymer is similar to that of the flexible polymer in the inner surface layer, but the types can be the same or different. In this case, the barrier properties of the film are improved, while balancing the film's flexibility and rigidity, preventing bags made from the film from being damaged by folding during use.

[0016] As a further improvement of the present invention, the thickness of the inner surface layer is 5 to 30 μm; and / or

[0017] The thickness of the single barrier layer is 5 to 20 μm and the hardness is 20 to 60 HD; and / or

[0018] The thickness of the single flexible layer is 5 to 50 μm, and the hardness is 30 to 80 HA.

[0019] As a further improvement of the present invention, adhesive layers are provided on both sides of the barrier layer. The adhesive layers comprise maleic anhydride-grafted polyethylene and ethylene-vinyl ester polymer. Preferably, the ethylene-vinyl ester polymer comprises ethylene-vinyl acetate copolymer and / or ethylene-vinyl propionate copolymer. The presence of the adhesive layers improves adhesion between the barrier layer and adjacent layers, preventing the formation of bubbles and delamination.

[0020] As a further improvement of the present invention, the mass proportion of maleic anhydride grafted polyethylene in the adhesive layer is 50-95%.

[0021] The thickness of the adhesive layer is not particularly limited and may be a conventional thickness in the art, such as 5-30 μm.

[0022] The material of the outer layer can be a conventional material in the art, such as at least one of polyolefins (such as polyethylene PE), flexible copolymers and polyesters (such as PET). The thickness of the outer layer can be 10 to 60 μm, and the hardness can be no more than 80 HD.

[0023] A second aspect of the present invention provides a method for preparing the multilayer co-extruded polymer film as described above, the method comprising the following steps:

[0024] S1. Prepare raw materials according to mass ratio;

[0025] S2. Co-extruding the above raw materials to form a multilayer film precursor;

[0026] S3, cooling the multilayer film precursor so that the temperature of the multilayer film precursor is not higher than Tg, thereby causing the cyclic olefin copolymer to undergo a glass transition;

[0027] S4, further cooling the system to form a multilayer co-extruded polymer film;

[0028] In step S1, the total mass content of the opening agent with a molecular weight of less than 500 g / mol and the inorganic opening agent in the raw material is less than 100 ppm;

[0029] In step S2, the extrusion temperature T3 of the inner surface layer is 2.2 to 2.8 times the melting point mp of the flexible copolymer of the inner surface layer.

[0030] The extrusion temperature T3 of the inner surface layer is 2.2 to 2.8 times the melting point mp of the flexible copolymer of the inner surface layer, which means that the extrusion temperature of the inner surface layer is not higher than 250°C. At this time, the diffusion performance distribution of the cycloolefin polymer component in the inner surface layer can be controlled, making it easier to form a crystalline structure on the inner surface.

[0031] As a further improvement of the present invention, the difference between the extrusion temperature T3 of the inner surface layer and the extrusion temperature T4 of the layer adjacent to the inner surface layer is no greater than 35°C. In this case, the inner surface layer and the adjacent layers exhibit excellent adhesion and are less likely to delaminate. Furthermore, this solution allows the inner surface layer to achieve a more crystalline state, allowing the COC therein to form a glassy state in the region closer to the outside, thereby significantly improving the system's separation and precipitation performance.

[0032] As a further improvement of the present invention, during the cooling step, water cooling is applied at least on the inner side of the multilayer coextruded polymer film, with the water cooling temperature being 15 to 30° C. In this case, the heat exchange efficiency on the inner side is improved, thereby increasing the crystallinity of the cyclic olefin copolymer, thereby enabling the cyclic olefin copolymer to better perform the function of separating adjacent films.

[0033] As a further improvement of the present invention, the intermediate layer comprises at least one barrier layer and at least one flexible layer, and the extrusion temperature T1 of the barrier layer and the extrusion temperature T2 of the flexible layer adjacent to the barrier layer meet the following relationship: 0°C < T1 - T2 < 30°C. In this case, good compatibility and interfacial adhesion between the barrier layer and the flexible layer are achieved, effectively improving the performance and quality of the multilayer co-extruded film while reducing interfacial defects caused by temperature differences.

[0034] In the present invention, the materials of different flexible layers can be the same, and the extrusion temperatures can be the same or different.

[0035] A third aspect of the present invention provides a bag comprising the multi-layer co-extruded polymer film as described above.

[0036] A fourth aspect of the present invention provides use of the multi-layer co-extruded polymer film or the bag as described above in the preparation of a biological fluid bag.

[0037] A fifth aspect of the present invention provides an application of a cyclic olefin copolymer in preparing a polymer film containing a flexible copolymer, wherein the application includes at least one of the following aspects:

[0038] (1) Inhibit the migration of unreacted monomers in the polymer film;

[0039] (2) Suppressing the adhesion of flexible copolymers caused by irradiation treatment;

[0040] (3) increasing the roughness of the polymer film;

[0041] (4) Improve the air tightness of the bag with a polymer film as the inner layer.

[0042] The multi-layer co-extruded polymer film provided by the present invention can be used to make biological liquid bags, so that the inner side of the bag is basically not cross-linked under irradiation conditions, and basically no small molecular substances seep out during use. Under preferred conditions, it can also have relatively balanced flexibility and rigidity, which is beneficial to improving the folding resistance of the product.

[0043] The endpoints and any values ​​of the ranges disclosed herein are not limited to the precise ranges or values, and these ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of each range, the endpoint values ​​of each range and the individual point values, and the individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be considered as specifically disclosed in this article. Herein, unless otherwise specified, data ranges include endpoints. DETAILED DESCRIPTION

[0044] The following is a detailed description of the specific embodiments of the present invention. It should be understood that the specific embodiments described herein are only used to illustrate and explain the present invention and are not intended to limit the present invention.

[0045] Unless otherwise defined, all scientific and technical terms used in the present invention have the same meanings as commonly understood by one of ordinary skill in the art to which the present invention relates.

[0046] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the embodiments described 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 making creative efforts are within the scope of protection of the present invention.

[0047] Unless otherwise specified, the materials and reagents used in the following examples can be obtained from commercial sources.

[0048] The present invention will be described in detail below with reference to specific embodiments. These embodiments are intended to help you understand the present invention but are not intended to limit it.

[0049] In the following examples, the performance testing method for the multi-layer co-extruded polymer film is as follows:

[0050] 1. Exudation performance: Determine the total extractable content of mixed bags according to the BPOG method and characterize by GC-MS.

[0051] 2. Mechanical properties: The mechanical properties of the membrane were determined according to ISO 527: (1) maximum load; (2) tensile length; (3) tensile strength; and (4) elongation. The specimen width was 5 mm, the tensile speed was 300 mm / min, and the gauge length was 30 mm.

[0052] 3. Adhesion strength measurement: Cut the corresponding film material into 10×10cm pieces, then laminate the two pieces and perform the corresponding treatment. Then use a tensile gauge to separate the two pieces of film at 90° from the edge in the vertical direction. Measure the pulling force required for separation. This pulling force is the adhesion strength.

[0053] The irradiation sterilization condition is a cumulative irradiation dose of 25 to 45 kGy; the aging condition is aging in an air environment at 60°C for 33 days.

[0054] In the following examples, hardness is measured by directly extruding the corresponding materials at the corresponding extrusion temperatures. If conditions permit, the hardness of the corresponding extruded layer can also be measured after separating or removing other layers from the co-extruded film by physical or chemical methods.

[0055] Unless otherwise specified, in the following examples, the cycloolefin copolymer COC is a copolymer of norbornene and ethylene, and COP is a copolymer of tetracyclododecene, and their glass transition temperatures Tg are shown in the following table. The content of vinyl ester units in the ethylene-vinyl acetate copolymer EVA, the melting point mp, and the hardness are also shown in the following table.

[0056]

[0057] Example 1

[0058] The multilayer co-extruded polymer film includes an outer surface layer, an inner surface layer and an intermediate layer. From the outer surface layer to the inner surface layer, the intermediate layer includes an adhesive layer, a flexible layer, a flexible layer, an adhesive layer, a barrier layer, an adhesive layer, a barrier layer, an adhesive layer and a flexible layer in sequence.

[0059] The method for preparing a multilayer co-extruded polymer film comprises the following steps: S1. Preparing raw materials according to a mass ratio; S2. Co-extruding the raw materials to form a multilayer film precursor; S3. Cooling the multilayer film precursor to maintain a temperature below Tg, thereby causing the cyclic olefin copolymer to undergo a glass transition; and S4. Further cooling the system to form a multilayer co-extruded polymer film. The material, thickness, hardness, and extrusion temperature of each layer are shown in Table 1, with a die temperature of 235°C. During the cooling step, water cooling is applied to the inner side of the multilayer co-extruded polymer film at a temperature of 20°C.

[0060] The inner surface layer includes 75 wt % of EVA1 and 25 wt % of COC1, and no opening agent other than COC1 is added. The adhesive layer includes 60 wt % of maleic anhydride grafted polyethylene and 40 wt % of EVA.

[0061] Calculations show that Tg-mp = 22, and W*(Tg-mp) = 5.5. The extrusion temperature T3 of the inner surface layer is 2.5 times the melting point mp of the flexible copolymer in the inner surface layer. The difference T4 between the extrusion temperature T3 of the inner surface layer and the extrusion temperature of the flexible layer adjacent to the inner surface layer is 25°C. The difference T1-T2 between the extrusion temperature T1 of the barrier layer and the extrusion temperature T2 of the flexible layer adjacent to the barrier layer is 25°C.

[0062] The results show that the leakage of small molecules from the multilayer co-extruded polymer film before and after irradiation is 0.201 μg / cm 2 and 0.222 μg / cm 2 , the maximum load is 18.5N, the tensile length is 422.2mm, the tensile strength is 23.0MPa, the elongation is 1238.1%, the modulus is 32.5MPa, the adhesion force when not sterilized is 0N, the adhesion force after sterilization is 0.335N, and the adhesion force after aging for 33 days after sterilization is 0.644N.

[0063] Table 1

[0064]

[0065]

[0066] Comparative Example 1

[0067] The process described in Example 1 was followed, except that no COC was added, ie, the composition of the inner surface layer was 100% EVA1.

[0068] The results of small molecule exudation and adhesion of the prepared multilayer co-extruded polymer film before and after irradiation are shown in Table 2-2.

[0069] Comparative Example 2

[0070] The method described in Comparative Example 1 was followed, except that EMA was used instead of EVA1, that is, the composition of the inner surface layer was 100% EMA.

[0071] The results of small molecule exudation and adhesion of the prepared multilayer co-extruded polymer film before and after irradiation are shown in Table 2-2.

[0072] Example 2 group

[0073] The process was carried out according to the method described in Example 1, except that at least one of the types of the cyclic olefin copolymer and the flexible copolymer was different, as shown in Table 2-1. Furthermore, during extrusion, the extrusion temperature T3 of the inner surface layer was controlled to be 2.5 times the melting point mp of the inner surface flexible copolymer, and the difference between the extrusion temperature T3 of the inner surface layer and the extrusion temperature T4 of the layer adjacent to the inner surface layer was maintained at 25°C.

[0074] The results of small molecule exudation and adhesion of the prepared multilayer co-extruded polymer film before and after irradiation are shown in Table 2-2.

[0075] Table 2-1

[0076]

[0077]

[0078] Table 2-2

[0079]

[0080]

[0081] From the data of Example 2 and Comparative Examples 1 and 2, it can be seen that without adding an anti-blocking agent, the multilayer co-extruded polymer film has a relatively obvious problem of small molecule leakage before irradiation. After irradiation, the amount of small molecule leakage increases significantly, which is 4.5 to 5 times that before irradiation, reaching 2 μg / cm 2 As mentioned above, when used to prepare biological fluid bags, it will significantly increase the impurities in the biological fluid, which has a very negative impact on product quality. Furthermore, despite not being sterilized, the multilayer co-extruded polymer films prepared in Comparative Examples 1 and 2 also have relatively high adhesion (above 4N), far greater than the films containing the anti-blocking agent. After sterilization, their adhesion is above 10N. In other words, the co-extruded polymer films have experienced serious polymer dissociation and cross-linking problems, making the films unusable.

[0082] In Example 2, different combinations of flexible copolymers and cycloolefin copolymers were compared. The data from Examples 2-22 and 2-23 show that when the glass transition temperature (Tg) of the cycloolefin copolymer is lower than 60°C and Tg < mp, the multilayer co-extruded polymer film exhibits a high adhesion strength even before sterilization. Furthermore, the greater the temperature difference between Tg and mp, the greater the adhesion strength. After sterilization, the adhesion strength is greater than 10N, indicating that the co-extruded polymer film under these conditions experiences varying degrees of polymer dissociation and cross-linking before and after sterilization, significantly affecting the reliability and life of the film. Furthermore, from the time the exudate reaches 0.3 μg / cm 2 It can be seen from the above that polymer dissociation has occurred before irradiation, and the dissociation is further aggravated after irradiation.

[0083] When the glass transition temperature Tg of the cycloolefin copolymer is not lower than 60°C, although there are differences in the effects when different flexible copolymers and cycloolefin copolymers are used in combination, when the glass transition temperature Tg of the cycloolefin copolymer is lower than the melting point mp of the flexible copolymer (such as Example 2-5, Example 2-12, Example 2-13, Example 2-15, Example 2-16, Example 2-18, Example 2-20), that is, Tg < mp, the multi-layer co-extruded polymer film will have a certain adhesion force when it is not sterilized, which means that the inner and outer layers cannot be effectively separated, especially after sterilization and aging for 33 days after sterilization, the adhesion force is greater than 7N, which means that the co-extruded polymer film has different degrees of polymer dissociation and cross-linking problems, which significantly affects the reliability and life of the film. In contrast, when the glass transition temperature Tg of the cyclic olefin copolymer is not less than 60°C and satisfies the relationship Tg≥mp with the melting point mp of the flexible copolymer, the adhesion between the membranes is basically 0 when not sterilized, and the adhesion of the membranes does not exceed 3N even after aging for 33 days after sterilization, indicating that the product has high stability and reliability. It can also be seen from the small molecule leakage before and after irradiation that the membrane provided by the present invention will basically not have small molecule leakage when used for storage in biological fluid bags, and the quality is stable. When 1≤W*(Tg-mp)≤15 is preferably satisfied, the small molecule leakage performance of the membrane after irradiation treatment can be further improved, and the amount of small molecule leakage after irradiation does not exceed 0.4μg / cm 2 At the same time, the adhesion of the film is significantly reduced after sterilization and after aging for 33 days after sterilization, indicating that the multi-layer co-extruded polymer film of the present invention can better separate adjacent inner surface layers, and can also prevent the flexible copolymers of the inner surface layer from being cross-linked after dissociation and cross-linking after irradiation sterilization, while reducing the liquid contamination caused by the outward migration of small molecules generated by the breakage of the flexible copolymer chain.

[0084] Example 3 group

[0085] The operation was carried out according to the method described in Example 1, except that the contents of the cycloolefin copolymer and the flexible copolymer were different, as shown in Table 3-1.

[0086] The mechanical properties and adhesion results of the prepared multilayer co-extruded polymer film are shown in Table 3-2.

[0087] Table 3-1

[0088]

[0089]

[0090] Table 3-2

[0091]

[0092]

[0093] The data from Examples 1 and 3-1 to 3-9 show that as the COC1 content increases, the mechanical properties and adhesion of the multilayer coextruded polymer film first improve and then decrease. In particular, when the COC1 content is within the preferred range (10-40%), better performance is achieved. Furthermore, when the COC1 content is within the preferred range, the leakage of small molecules after irradiation is reduced, with the leakage of small molecules after irradiation ranging from 0.2 to 0.31 μg / cm 2 The exudation rate is lower than that of the non-preferred content (0.34-0.56 μg / cm 2 This indicates that the addition of an appropriate amount of polyolefin copolymer is beneficial to further improve the stability of the inner surface layer, reduce the degree of cracking of the flexible copolymer during irradiation sterilization, and reduce the dissolution of small molecules during the use of the bag.

[0094] From the data of Examples 3-10 to 3-13, Examples 2-10 and 3-14, and Examples 2-24 and 3-16, it can be seen that although the content of cycloolefin copolymer is within the preferred range, when it does not satisfy 1≤W*(Tg-mp)≤15, the tensile length of the co-extruded polymer film is relatively small, and the adhesion (especially after aging for 33 days after sterilization) is relatively high. In Examples 3-12 to 3-13 and 3-16, the leakage of small molecules after irradiation is relatively high, ranging from 0.6 to 1 μg / cm 2 This indicates that when the mass proportion of cyclic olefin copolymers is between 10% and 40% and the W*(Tg-mp) relationship is satisfied, it is beneficial to improve the stability of the inner surface layer, reduce the degree of cracking of the flexible copolymer during irradiation sterilization, and reduce the dissolution of small molecules during the use of the bag.

[0095] From the data of Examples 3-15, it can be seen that the adhesion of the coextruded polymer film is too high, even higher than that of Examples 2-15. This shows that although the content of cycloolefin copolymer is within the preferred range, when it does not satisfy Tg≥mp and 1≤W*(Tg-mp)≤15, even if the mass proportion of cycloolefin copolymer is further increased within the preferred range, the dissociation of the polymer cannot be alleviated.

[0096] Example 4 Group

[0097] The operation was carried out according to the method described in Example 1, except that the structure of the multi-layer co-extruded polymer film was different.

[0098] Example 4-1: A multilayer coextruded polymer film includes two barrier layers, and the barrier layer materials and thickness are the same as those in Example 1. From the outer surface layer to the inner surface layer, the multilayer coextruded polymer film includes, in order: an outer surface layer, an adhesive layer, a barrier layer, an adhesive layer, a barrier layer, an adhesive layer, three flexible layers, an adhesive layer, and an inner surface layer.

[0099] Example 4-2: The structure of the multi-layer co-extruded polymer film is the same as that of Example 4-1, except that the material of the barrier layer close to the inner surface layer is PA.

[0100] Example 4-3: The total thickness of the multi-layer co-extruded polymer film remains unchanged, the number of flexible layers is 2, and the thickness of each flexible layer is 90 μm.

[0101] Example 4-4: The material of the flexible layer is different, using EVA2 instead of EVA1.

[0102] Example 4-5: The material of the flexible layer is different, using EVA3 instead of EVA1.

[0103] The results of small molecule exudation and adhesion of the prepared multilayer co-extruded polymer film before and after irradiation are shown in Table 4.

[0104] Table 4

[0105]

[0106]

[0107] As can be seen from Table 4, the above-mentioned changes in the barrier layer and the flexible layer have little significant effect on the permeation performance. In various arrangements of the barrier layer and the flexible layer, good separation performance can be achieved while the inner surface layer remains unchanged.

[0108] From the comparison of the data of Examples 4-1 and 4-2, it can be seen that when the inner barrier layer of the multi-layer co-extruded polymer film is PA and the outer barrier layer is EVOH, it is beneficial to reduce the leakage of small molecules.

[0109] Example 5 Group

[0110] The method described in Example 1 was followed, except that at least one of the extrusion temperature T3 of the inner surface layer, the extrusion temperature T1 of the barrier layer, and the extrusion temperature T2 / T4 of the flexible layer was different, as shown in Table 5-1.

[0111] It should be noted that in this embodiment, T2 and T4 use the same value. In practice, different temperatures can be used to set the temperature of each flexible layer according to the specific selection of the flexible layer.

[0112] The results of the small molecule exudation and adhesion of the prepared multilayer co-extruded polymer film before and after irradiation are shown in Table 5-2.

[0113] Table 5

[0114]

[0115]

[0116] Table 5-2

[0117]

[0118] Example 1 and Examples 5-1 to 5-5 compare the influence of the change of T3 and T3-T2 on the film performance due to the change of T3, and it can be seen from the table that when the multiple of the inner skin layer extrusion temperature T3 and the melting point mp of the flexible copolymer of the inner skin layer exceeds the range of 2.2-2.8 times, the small molecule exudation before and after irradiation is slightly high, the increase ratio of the small molecule exudation after irradiation is also relatively high, the maximum load and tensile length are small, which indicates that the polymer performance of the film itself is slightly poor, the polymer has a certain dissociation, and especially in Example 5-1, the polymer also has a certain crosslinking condition, which leads to the adhesion being relatively high.

[0119] Example 1 and Examples 5-8 to 5-10 compare the influence of the change of T3-T4 on the film performance due to the change of the extrusion temperature T4 of the flexible layer adjacent to the inner skin layer, and it can be seen that as the difference between T3 and T4 increases, on the one hand, it has a certain influence on the physical performance of the film, and the reason may be that the interlayer structure compatibility decreases due to the larger temperature difference, which in turn leads to the film being more easily torn in the plane, on the other hand, the force required for the separation between the layers is obviously improved, which proves that when there is an excessive extrusion temperature difference between the inner skin layer and the flexible layer adjacent thereto, it will have a significant influence on the glass transition performance of COC in the inner skin layer.

[0120] It is to be understood that the terminology "including", "containing" or any other variation thereof does not exclude the presence of other elements or steps than those listed in the process, method, article, or apparatus. It is further understood that the steps and elements recited in any of the examples herein can be combined, removed or arranged in various ways without departing from the scope of the application. Further, the features described in relation to one example can be combined with features described in relation to other examples.

[0121] The above description is merely illustrative of the application and does not in any way delimit the scope of the application. Any modification, equivalent replacement or the like made within the spirit and principle of the application shall fall within the scope of the application.

Claims

1. A multilayer coextruded polymer film, characterized in that The multilayer co-extruded polymer film comprises an outer layer, an inner layer and an intermediate layer, wherein the inner layer comprises a flexible copolymer and a cycloolefin copolymer, wherein the flexible copolymer comprises an ethylene-vinyl ester polymer, and the glass transition temperature Tg of the cycloolefin copolymer is not lower than 60° C. and satisfies the relationship Tg≥mp with the melting point mp of the flexible copolymer. In addition, in the inner surface layer of the multi-layer co-extruded polymer film, the total mass content of the opening agent with a molecular weight of less than 500 g / mol and the inorganic opening agent is less than 100 ppm.

2. The multilayer coextruded polymer film according to claim 1, characterized in that Tg-mp≥5℃.

3. The multilayer coextruded polymer film according to claim 2, characterized in that In the inner surface layer, the mass proportion of the cycloolefin copolymer is 10 to 40%; Preferably, the relationship between the mass proportion W of the cycloolefin copolymer in the inner surface layer and the value of Tg-mp is 1≤W*(Tg-mp)≤15.

4. The multi-layer coextruded polymer film according to claim 1, characterized in that The flexible copolymer includes at least one of ethylene-vinyl acetate copolymer, ethylene-vinyl propionate copolymer, and ethylene-vinyl butyrate copolymer.

5. The multi-layer coextruded polymer film according to claim 4, characterized in that The content of vinyl ester units in the ethylene-vinyl ester polymer is 9-28 mol%.

6. The multilayer coextruded polymer film according to claim 5, characterized in that The Shore A hardness of the flexible copolymer is 60 to 90 HA.

7. The multi-layer coextruded polymer film according to claim 4, characterized in that The flexible copolymer is ethylene-vinyl acetate copolymer.

8. The multi-layer coextruded polymer film according to claim 1, characterized in that The cycloolefin copolymer is a copolymer of norbornene and ethylene.

9. The multi-layer coextruded polymer film according to claim 1, characterized in that The intermediate layer comprises at least one barrier layer and at least one flexible layer, wherein the barrier layer comprises ethylene-vinyl alcohol copolymer and / or polyamide, and the flexible layer comprises a flexible copolymer.

10. The multi-layer coextruded polymer film according to claim 9, characterized in that The thickness of the inner surface layer is 5 to 30 μm; and / or The thickness of the single barrier layer is 5 to 20 μm and the hardness is 20 to 60 HD; and / or The thickness of the single flexible layer is 5 to 50 μm, and the hardness is 30 to 80 HA.

11. The multi-layer coextruded polymer film according to claim 9, characterized in that Adhesive layers are provided on both sides of the barrier layer. The adhesive layers comprise maleic anhydride grafted polyethylene and ethylene-vinyl ester polymer. The ethylene-vinyl ester polymer comprises ethylene-vinyl acetate copolymer and / or ethylene-vinyl propionate copolymer.

12. The multi-layer coextruded polymer film according to claim 11, characterized in that The weight proportion of maleic anhydride grafted polyethylene in the adhesive layer is 50-95%.

13. The method for preparing a multi-layer co-extruded polymer film according to any one of claims 1 to 12, characterized in that: The method comprises the following steps: S1. Prepare raw materials according to mass ratio; S2. Co-extruding the above raw materials to form a multilayer film precursor; S3, cooling the multilayer film precursor so that the temperature of the multilayer film precursor is not higher than Tg, thereby causing the cyclic olefin copolymer to undergo a glass transition; S4, further cooling the system to form a multilayer co-extruded polymer film; In step S1, the total mass content of the opening agent with a molecular weight of less than 500 g / mol and the inorganic opening agent in the raw material is less than 100 ppm; In step S2, the extrusion temperature T3 of the inner surface layer is 2.2 to 2.8 times the melting point mp of the flexible copolymer of the inner surface layer.

14. The preparation method according to claim 13, characterized in that The difference between the extrusion temperature T3 of the inner surface layer and the extrusion temperature T4 of the layer adjacent to the inner surface layer is not greater than 35°C.

15. The preparation method according to claim 13, characterized in that In the cooling step, water cooling is used at least on the inner side of the multi-layer co-extruded polymer film, and the water cooling temperature is 15-30°C.

16. The preparation method according to claim 13, characterized in that The middle layer comprises at least one barrier layer and at least one flexible layer, and the extrusion temperature T1 of the barrier layer and the extrusion temperature T2 of the flexible layer adjacent to the barrier layer have the following relationship: 0°C < T1-T2 < 30°C.

17. A bag, characterized in that: The bag comprises the multilayer coextruded polymer film according to any one of claims 1 to 12.

18. Use of the multilayer co-extruded polymer film according to any one of claims 1 to 12 or the bag according to claim 17 in the preparation of a biological fluid bag.

19. Use of a cyclic olefin copolymer in preparing a polymer film containing a flexible copolymer, said use comprising at least one of the following aspects: (1) Inhibit the migration of unreacted monomers in the polymer film; (2) Suppressing the adhesion of flexible copolymers caused by irradiation treatment; (3) increasing the roughness of the polymer film; (4) Improve the air tightness of the bag with a polymer film as the inner layer.

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