Plastic film for packaging medical non-woven fabric and preparation method thereof

Abstract

The invention provides a plastic film for packaging a medical non-woven fabric and a preparation method of the plastic film. The plastic film comprises a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside, the polyimide layer is prepared from the following raw materials: 4, 4-diaminodiphenyl ether, pyromellitic dianhydride, a polyimide coated nano titanium dioxide / tetrapod-like zinc oxide whisker composite material and modified diatomite; the polyimide layer in the plastic film has excellent steam sterilization resistance and good radiation resistance, and after the polyimide layer is matched with the ethylene-vinyl alcohol copolymer layer and the polypropylene layer, the plastic film not only has excellent gas and microorganism barrier properties, but also can adapt to the modes of high-temperature steam sterilization, gamma ray irradiation sterilization and the like; the high mechanical property is kept for a long time, and the risk of damage caused by external force is reduced.

Description

Technical Field

[0001] The invention relates to the technical field of packaging materials, and in particular to a plastic film for packaging medical non-woven fabrics and a preparation method thereof. Background Art

[0002] At present, medical non-woven fabrics are widely used, for example, in medical surgical gowns, wound dressings, etc. Medical non-woven fabrics are generally vacuum-packed in plastic film bags. Maintaining the vacuum in the bag is crucial to protecting the non-woven fabrics, and it is necessary to block the infiltration of external oxygen, water vapor and other gases. Therefore, the plastic film used to package medical non-woven fabrics needs to have high gas barrier properties, and in order to better maintain the sterility of medical non-woven fabrics, the plastic film needs to be able to adapt to a variety of sterilization methods, such as high-temperature steam sterilization, gamma ray irradiation sterilization, etc.; after being sterilized by these sterilization methods, the plastic film needs to still maintain excellent film strength to reduce the risk of subsequent damage caused by external forces.

[0003] Therefore, the main support layer of the plastic film needs to be able to maintain structural stability under steam sterilization. At the same time, the main support layer of the plastic film is also required to have certain radiation resistance to reduce the strength degradation of the film material caused by molecular chain breakage. Summary of the invention

[0004] The object of the present invention is to provide a plastic film for packaging medical non-woven fabrics and a preparation method thereof. The polyimide layer in the plastic film has excellent resistance to steam sterilization and good radiation resistance. After being combined with an ethylene-vinyl alcohol copolymer layer and a polypropylene layer, it not only has excellent gas and microbial barrier properties, but also can adapt to high-temperature steam sterilization, gamma ray irradiation sterilization and the like, and maintains high mechanical properties for a long time, reducing the risk of damage due to external forces.

[0005] To achieve the above objectives, the present invention is implemented through the following technical solutions: A plastic film for packaging medical non-woven fabrics, the plastic film comprising a polyimide layer, an ethylene-vinyl alcohol copolymer layer, and a polypropylene layer from outside to inside; The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, and modified diatomite; the molar ratio of the 4,4-diaminodiphenyl ether to the pyromellitic acid dianhydride is 1:1.00-1.05; the addition amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.6-0.85% of the total mass of the 4,4-diaminodiphenyl ether and the pyromellitic acid dianhydride, and the addition amount of the modified diatomite is 2.5-4% of the total mass of the 4,4-diaminodiphenyl ether and the pyromellitic acid dianhydride.

[0006] Preferably, the polyimide-coated nano-titanium dioxide / tetrapodal zinc oxide whisker composite material comprises nano-titanium dioxide / tetrapodal zinc oxide whiskers and a polyimide coating layer coated on the outside of the nano-titanium dioxide / tetrapodal zinc oxide whiskers, and the nano-titanium dioxide / tetrapodal zinc oxide whisker composite material comprises tetrapodal zinc oxide whiskers and nano-titanium dioxide supported on the surface of the tetrapodal zinc oxide whiskers; the polyimide coating layer is obtained by polymerizing 4,4-diaminodiphenyl ether and pyromellitic acid anhydride to obtain polyamic acid and then imidizing.

[0007] Preferably, the preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material comprises the following steps: 1) placing a tetrapod-shaped zinc oxide crystal water dispersion in a reactor, and then slowly adding a titanium tetrachloride aqueous solution while stirring the tetrapod-shaped zinc oxide crystal water dispersion, after the addition is complete, closing the reactor, heating to 100-105° C. and continuing to stir and react for 3-6 hours, then cooling to room temperature, filtering, washing with water, and vacuum drying to obtain the nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material; 2) Add nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material to N,N-dimethylacetamide, add 4,4-diaminodiphenyl ether under ultrasonic stirring conditions, and after complete dissolution, add pyromellitic anhydride in 3 to 4 portions, and after complete dissolution, stir and react at 5 to 8° C. for 3 to 5 hours, centrifuge the obtained suspension, imide the obtained precipitate, and grind it to obtain the polyimide-coated nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material.

[0008] Preferably, the method for preparing the tetra-needle zinc oxide crystal water dispersion comprises the following steps: calculating by weight, placing 2 to 3.5 parts of tetra-needle zinc oxide whiskers in 100 parts of deionized water, adding 0.1 to 0.5 parts of tetradecyl dimethyl amine oxide, stirring and dispersing, and then ultrasonically treating to obtain a tetra-needle zinc oxide crystal water dispersion; the method for preparing the titanium tetrachloride aqueous solution comprises the following steps: in an ice-water bath, adding 0.2 to 0.5 parts of titanium tetrachloride to 20 to 30 parts of deionized water to prepare a titanium tetrachloride aqueous solution.

[0009] Preferably, when preparing the polyimide-coated nano-titanium dioxide / tetrapodal zinc oxide whisker composite material, the molar ratio of 4,4-diaminodiphenyl ether to pyromellitic acid dianhydride is 1:1.00-1.05; the added amount of the nano-titanium dioxide / tetrapodal zinc oxide whisker composite material is 35-55% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride.

[0010] Preferably, the preparation method of the modified diatomite comprises the following steps: Calculated by weight, 10 parts of diatomite and 0.5-1 parts of nano starch are added to 100 parts of water, and the mixture is fully mixed and filtered; the obtained filter cake is vacuum dried, and then heated to 600-650°C at a heating rate of 2-6°C / min in an air atmosphere for calcination, and the temperature is kept for 1.5-2h; after cooling to room temperature, the mixture is ground and passed through a 400-mesh sieve to obtain pre-treated diatomite; the pre-treated diatomite is placed in a silane coupling agent solution, stirred at a speed of more than 600r / min for 60-90min, and then ultrasonically treated for 60-90min, and then filtered, washed with water, and vacuum dried to obtain the modified diatomite. The method is to fully mix the nano starch with the diatomite, and then vacuum dry and calcine the filtered filter cake, so that the nano starch is fully calcined and decomposed at high temperature, so that more pores are formed in the diatomite.

[0011] Preferably, the thickness ratio of the polyimide layer, the ethylene-vinyl alcohol copolymer layer, and the polypropylene layer is 25~35:20~30:30~40; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

[0012] Preferably, the preparation method of the polyimide layer comprises the following steps: using 4,4-diaminodiphenyl ether as a diamine monomer and pyromellitic acid dianhydride as a dianhydride monomer, copolymerizing in N,N-dimethylacetamide to obtain a polyamic acid mixed solution; adding a polyimide-coated nano-titanium dioxide / tetra-needle zinc oxide whisker composite material and modified diatomaceous earth to the polyamic acid mixed solution, stirring and ultrasonically dispersing the mixture, coating the obtained mixed solution and performing a desolventizing treatment after vacuum degassing to obtain a polyamic acid film, and imidizing the polyamic acid film to obtain the polyimide layer.

[0013] Preferably, when preparing the polyimide layer, the added amount of the N,N-dimethylacetamide is 6 to 8 times the total mass of 4,4-diaminodiphenyl ether and pyromellitic dianhydride.

[0014] The present invention also provides a method for preparing a plastic film for packaging medical non-woven fabrics, comprising the following steps: An adhesive is coated on the side of the polyimide layer facing the ethylene-vinyl alcohol copolymer layer, and then bonded with the ethylene-vinyl alcohol copolymer layer, and then placed in a compounding machine for compounding to obtain an intermediate composite layer; an adhesive is then coated on the side of the intermediate composite layer facing the polypropylene layer, and bonded with the polypropylene layer, and then placed in a compounding machine for compounding to obtain the plastic film for packaging medical non-woven fabrics.

[0015] The beneficial effects of the present invention are: The plastic film of the present invention includes a polyimide layer, an ethylene-vinyl alcohol copolymer layer, and a polypropylene layer from the outside to the inside, wherein the ethylene-vinyl alcohol copolymer layer exhibits excellent gas and microbial barrier properties and can keep the plastic film relatively flexible; the inner polypropylene layer is in good contact with the non-woven fabric, and can ensure the safety of the medical non-woven fabric after sterilization. The outer polyimide layer plays a main supporting role for the plastic film and a preliminary gas and microbial barrier role.

[0016] The present invention adds a composite material of polyimide-coated nano titanium dioxide / tetrapod-shaped zinc oxide whisker and modified diatomite to a polyimide layer, wherein the tetrapod-shaped zinc oxide whisker and the modified diatomite are combined to effectively improve the strength of polyimide and its resistance to steam sterilization and radiation resistance. The tetrapod-shaped zinc oxide whisker is combined with the nano titanium dioxide on its surface, and the two cooperate synergistically to effectively absorb and scatter gamma ray radiation energy, reduce radiation damage to the polyimide layer, and reduce the breakage and degradation of the polyimide molecular chain by capturing free radicals; and by loading nano titanium dioxide on the surface of the tetrapod-shaped zinc oxide whisker, the surface roughness of the tetrapod-shaped zinc oxide whisker can be improved, which is conducive to forming a stable coating with the polyimide coating layer. The setting of the polyimide coating layer effectively enhances the dispersibility of the nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material in the polyimide layer preparation system, and significantly enhances the subsequent bonding force with the polyimide layer substrate, so that the polyimide layer maintains higher stability and durability in steam sterilization environments and gamma ray irradiation sterilization environments.

[0017] The modified diatomaceous earth added in the present invention has higher porosity and specific surface area than diatomaceous earth modified only by silane coupling agent. It can not only better improve the structural stability of the polyimide layer under steam sterilization, but also more effectively disperse the radiation energy due to its high porosity, further reduce the molecular chain breakage of polyimide, and improve the radiation resistance of the polyimide layer. DETAILED DESCRIPTION

[0018] In order to make the purpose, technical solution and advantages of the embodiments of the present invention clearer, the technical solution in the embodiments of the present invention will be clearly and completely described below in combination with the embodiments of the present invention. Obviously, the described embodiments are 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.

[0019] Embodiment 1: A plastic film for packaging medical non-woven fabrics, comprising a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside; the thickness of the polyimide layer is 25 μm, the thickness of the ethylene-vinyl alcohol copolymer layer is 25 μm, and the thickness of the polypropylene layer is 35 μm; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

[0020] The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, modified diatomite, and N,N-dimethylacetamide; the molar ratio of 4,4-diaminodiphenyl ether to pyromellitic acid dianhydride is 1:1.01; the added amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.80% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride, the added amount of the modified diatomite is 3% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride; the added amount of N,N-dimethylacetamide is 6.5 times the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride.

[0021] The preparation method of the polyimide layer in this embodiment comprises the following steps: Add 4,4-diaminodiphenyl ether to the reaction bottle, then add N,N-dimethylacetamide, stir, after 4,4-diaminodiphenyl ether is completely dissolved, add pyromellitic anhydride in 4 times, after it is completely dissolved, stir and react at 8°C for 3 hours to obtain a polyamic acid mixed solution; add polyimide-coated nano-titanium dioxide / tetra-needle-shaped zinc oxide whisker composite material and modified diatomaceous earth to the polyamic acid mixed solution, stir and simultaneously perform ultrasonic dispersion for 1 hour, the stirring speed is 200 r / min, the power of ultrasonic dispersion is 65 0W, after vacuum degassing, coating the obtained mixed solution on a clean glass plate, and then performing a desolventizing treatment to obtain a polyamic acid film, and imidizing the polyamic acid film, the imidization comprising the following steps: first heating to 65°C and maintaining for 80 min, then heating to 130°C and maintaining for 80 min, then heating to 220°C and maintaining for 80 min, and then heating to 260°C and maintaining for 80 min; then immersing the glass plate in pure water, removing the film and performing vacuum drying to obtain a polyimide film, thereby obtaining a polyimide layer.

[0022] In this embodiment, the polyimide-coated nano-titanium dioxide / tetra-needle-shaped zinc oxide whisker composite material includes nano-titanium dioxide / tetra-needle-shaped zinc oxide whiskers and a polyimide coating layer coated on the outside of the nano-titanium dioxide / tetra-needle-shaped zinc oxide whiskers. The nano-titanium dioxide / tetra-needle-shaped zinc oxide whisker composite material includes tetra-needle-shaped zinc oxide whiskers and nano-titanium dioxide loaded on the surface of the tetra-needle-shaped zinc oxide whiskers.

[0023] The preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material comprises the following steps: 1) 30 g of tetrapod-shaped zinc oxide whiskers (particle size of 100-800 nm) were placed in 1000 g of deionized water, and 2 g of tetradecyl dimethyl amine oxide was added, and the mixture was dispersed by stirring and then ultrasonicated to obtain a tetrapod-shaped zinc oxide crystal water dispersion; 3 g of titanium tetrachloride was added to 300 g of deionized water in an ice-water bath to obtain a titanium tetrachloride aqueous solution; 2) placing a tetrapod-shaped zinc oxide crystal water dispersion in a reaction kettle, and then slowly adding a titanium tetrachloride aqueous solution while stirring the tetrapod-shaped zinc oxide crystal water dispersion. After the addition is completed, the reaction kettle is closed, and the temperature is raised to 105° C. and the stirring reaction is continued for 5 hours, and then cooled to room temperature, and then filtered, washed with water, and vacuum dried to obtain the nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material; 2) Add 18.5g of nano titanium dioxide / tetrapodal zinc oxide whisker composite material to 1kg of N,N-dimethylacetamide, add 20.02g of 4,4-diaminodiphenyl ether under ultrasonic stirring conditions, and after complete dissolution, add 21.86g of pyromellitic anhydride in 4 portions, and after complete dissolution, stir and react at 7°C for 4.5h, centrifuge the obtained suspension, and imidize the obtained precipitate, which includes the following steps: first heat the precipitate to 75°C and keep it for 60min, then heat it to 130°C and keep it for 60min, then heat it to 220°C and keep it for 60min, and then heat it to 255°C and keep it for 60min; then grind it to obtain a polyimide-coated nano titanium dioxide / tetrapodal zinc oxide whisker composite material.

[0024] The preparation method of modified diatomite in this embodiment comprises the following steps: Add 100g of diatomaceous earth and 8g of nano starch (with a particle size of 100-200nm) to 1kg of water, mix thoroughly and filter; after vacuum drying the obtained filter cake, heat it to 620℃ at a heating rate of 5℃ / min in an air atmosphere for calcination, and keep it warm for 2h; after cooling to room temperature, grind it and pass it through a 400-mesh sieve to obtain pretreated diatomaceous earth; place the pretreated diatomaceous earth in 2kg of silane coupling agent solution, stir it at a speed of 800r / min for 70min, then ultrasonically treat it for 80min, and then filter it, wash it with water, and vacuum dry it to obtain modified diatomaceous earth; The preparation method of the silane coupling agent solution comprises the following steps: mixing ethanol and deionized water in a mass ratio of 2:1, then adding silane coupling agent KH550 in an amount of 1.5% by mass of the deionized water, stirring and mixing, and obtaining the silane coupling agent solution.

[0025] The method for preparing the plastic film for medical non-woven packaging in this embodiment comprises the following steps: The polyurethane adhesive is applied to the side of the polyimide layer facing the ethylene-vinyl alcohol copolymer layer, and the coating amount of the polyurethane adhesive is controlled to be 1.5 g / m 2 , and then bonded with the ethylene-vinyl alcohol copolymer layer, and then placed in a compounding machine for compounding to obtain an intermediate composite layer; and then the side of the intermediate composite layer facing the polypropylene layer is coated with a polyurethane adhesive, and the coating amount of the polyurethane adhesive is controlled at 1.5g / m 2 and bonded with the polypropylene layer, and then placed in a compounding machine for compounding to obtain a plastic film for packaging medical non-woven fabrics.

[0026] Embodiment 2: A plastic film for packaging medical non-woven fabrics, comprising a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside; the thickness of the polyimide layer is 25 μm, the thickness of the ethylene-vinyl alcohol copolymer layer is 25 μm, and the thickness of the polypropylene layer is 35 μm; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

[0027] The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, modified diatomite, and N,N-dimethylacetamide; the molar ratio of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride is 1:1; the added amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.85% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride, the added amount of the modified diatomite is 2.5% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride; the added amount of N,N-dimethylacetamide is 6.5 times the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride.

[0028] The preparation method of the polyimide layer, the preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material, and the preparation method of the modified diatomaceous earth in this embodiment are all the same as those in Example 1.

[0029] The method for preparing the plastic film for medical non-woven fabric packaging in this embodiment is the same as that in Example 1.

[0030] Embodiment 3: A plastic film for packaging medical non-woven fabrics, comprising a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside; the thickness of the polyimide layer is 25 μm, the thickness of the ethylene-vinyl alcohol copolymer layer is 25 μm, and the thickness of the polypropylene layer is 35 μm; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

[0031] The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, modified diatomite, and N,N-dimethylacetamide; the molar ratio of 4,4-diaminodiphenyl ether to pyromellitic acid dianhydride is 1:1.05; the added amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.72% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride, the added amount of the modified diatomite is 3% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride; the added amount of N,N-dimethylacetamide is 6.5 times of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride.

[0032] The preparation method of the polyimide layer, the preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material, and the preparation method of the modified diatomaceous earth in this embodiment are all the same as those in Example 1.

[0033] The method for preparing the plastic film for medical non-woven fabric packaging in this embodiment is the same as that in Example 1.

[0034] Embodiment 4: A plastic film for packaging medical non-woven fabrics, comprising a polyimide layer, an ethylene-vinyl alcohol copolymer layer and a polypropylene layer from outside to inside; the thickness of the polyimide layer is 25 μm, the thickness of the ethylene-vinyl alcohol copolymer layer is 25 μm, and the thickness of the polypropylene layer is 35 μm; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

[0035] The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, modified diatomite, and N,N-dimethylacetamide; the molar ratio of 4,4-diaminodiphenyl ether to pyromellitic acid dianhydride is 1:1.02; the added amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.6% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride, the added amount of the modified diatomite is 4% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride; the added amount of N,N-dimethylacetamide is 6.5 times the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid dianhydride.

[0036] The preparation method of the polyimide layer, the preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material, and the preparation method of the modified diatomaceous earth in this embodiment are all the same as those in Example 1.

[0037] The method for preparing the plastic film for medical non-woven fabric packaging in this embodiment is the same as that in Example 1.

[0038] Comparative Example 1: The method is substantially the same as Example 4, except that the raw material polyimide-coated nano-titanium dioxide / tetrapodial zinc oxide whisker composite material used in the polyimide layer is replaced with tetrapodial zinc oxide whiskers.

[0039] Comparative Example 2: The method is basically the same as Example 4, except that the raw material polyimide coated nano titanium dioxide / tetrapodal zinc oxide whisker composite material used in the polyimide layer is replaced by the nano titanium dioxide / tetrapodal zinc oxide whisker composite material prepared by the method in Example 1.

[0040] Comparative Example 3: The method is basically the same as Example 4, except that the raw material polyimide-coated nano-titanium dioxide / tetrapodal zinc oxide whisker composite material used in the polyimide layer is replaced by polyimide-coated tetrapodal zinc oxide whiskers.

[0041] The preparation method of polyimide coated tetrapod-shaped zinc oxide whiskers comprises the following steps: 18.5 g of tetrapod-shaped zinc oxide whiskers (particle size of 100-800 nm) were added to 1 L of N, N-dimethylacetamide, and 20.02 g of 4, 4-diaminodiphenyl ether was added under ultrasonic stirring. After complete dissolution, 21.86 g of pyromellitic anhydride was added in 4 portions. After complete dissolution, the mixture was stirred at 7°C for 4.5 h. The obtained suspension was centrifuged and the obtained precipitate was imidized. The imidization step included the following steps: the precipitate was first heated to 75°C and maintained for 60 min, then heated to 130°C and maintained for 60 min, then heated to 220°C and maintained for 60 min, and then heated to 255°C and maintained for 60 min; then ground to obtain polyimide-coated tetrapod-shaped zinc oxide whiskers.

[0042] Comparative Example 4: The method is basically the same as Example 4, except that the modified diatomite is prepared by the following method: 100 g of diatomite is ground and passed through a 400-mesh sieve, then placed in 2 kg of a silane coupling agent solution, stirred at a speed of 800 r / min for 70 min, and then ultrasonically treated for 80 min, and then filtered, washed with water, and vacuum dried to obtain the modified diatomite; the preparation method of the silane coupling agent solution comprises the following steps: ethanol and deionized water are mixed in a mass ratio of 2:1, and then a silane coupling agent of 1.5% by mass of the deionized water is added, and the mixture is stirred to obtain a silane coupling agent solution.

[0043] Performance Testing: The tensile strength of the polyimide layer prepared in Examples 1 to 4 and Comparative Examples 1 to 4 was tested according to the standard of ASTM D882, and the tensile strength of the polyimide layer after steam sterilization (130°C) for 10 times was tested, and the time of each steam sterilization was 20 minutes; and the tensile strength of the polyimide layer after gamma ray irradiation sterilization for 10 times was tested, and the radiation dose of each gamma ray irradiation sterilization was 25.0 kGy. The test results are shown in Table 1.

[0044] Table 1: Tensile strength / MPa After steam sterilization 10 times / MPa After 10 times of gamma ray sterilization / MPa Example 1 186.2 184.9 184.0 Example 2 187.6 186.0 185.7 Example 3 184.1 182.5 181.5 Example 4 183.0 181.5 180.7 Comparative Example 1 165.2 158.3 152.1 Comparative Example 2 172.5 168.0 164.7 Comparative Example 3 176.6 172.9 166.3 Comparative Example 4 175.3 169.0 168.3 As shown in Table 1, the polyimide layers prepared in Examples 1 to 4 and Comparative Examples 1 to 4 have high tensile strengths, which can reach more than 180 MPa, and the tensile strength attenuation of the polyimide layers is small after 10 steam sterilizations and 10 gamma ray sterilizations.

[0045] From the comparison between Comparative Example 1 and Example 4, it can be seen that the tetrapod-shaped zinc oxide whiskers are modified by nano-titanium dioxide and coated with polyimide at the same time, which plays a significant positive role in improving the steam sterilization resistance and radiation resistance of the polyimide layer.

[0046] From the comparison between Comparative Example 2 and Example 4, it can be seen that the use of polyimide to coat the nano-titanium dioxide / tetra-needle zinc oxide whisker composite material has a significant positive effect on improving the radiation resistance of the polyimide layer, and can also improve the steam sterilization resistance to a certain extent.

[0047] From the comparison between Comparative Example 3 and Example 4, it can be seen that the modification of the tetrapod-shaped zinc oxide whisker composite material with nano-titanium dioxide plays a significant positive role in improving the radiation resistance of the polyimide layer, and can improve the steam sterilization resistance to a certain extent.

[0048] From the comparison between Comparative Example 4 and Example 4, it can be seen that the porous modification of diatomaceous earth plays a significant positive role in improving the steam sterilization resistance and radiation resistance of the polyimide layer.

[0049] The polyimide layer of the present invention is combined with an ethylene-vinyl alcohol copolymer layer and a polypropylene layer to prepare a plastic film for packaging medical non-woven fabrics, which can give the plastic film higher stability and durability.

[0050] The above embodiments are only used to illustrate the technical solutions of the present invention, rather than to limit the same. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art should understand that the technical solutions described in the aforementioned embodiments may still be modified, or some of the technical features may be replaced by equivalents. However, these modifications or replacements do not deviate the essence of the corresponding technical solutions from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A plastic film for packaging medical non-woven fabrics, characterized in that: The plastic film comprises, from outside to inside, a polyimide layer, an ethylene-vinyl alcohol copolymer layer, and a polypropylene layer; The polyimide layer comprises the following raw materials: 4,4-diaminodiphenyl ether, pyromellitic acid dianhydride, polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material, and modified diatomite; the molar ratio of the 4,4-diaminodiphenyl ether to the pyromellitic acid dianhydride is 1:1.00-1.05; the addition amount of the polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material is 0.6-0.85% of the total mass of the 4,4-diaminodiphenyl ether and the pyromellitic acid dianhydride, and the addition amount of the modified diatomite is 2.5-4% of the total mass of the 4,4-diaminodiphenyl ether and the pyromellitic acid dianhydride.

2. The plastic film for packaging medical nonwoven fabrics according to claim 1, characterized in that: The polyimide coated nano titanium dioxide / tetrapodal zinc oxide whisker composite material comprises nano titanium dioxide / tetrapodal zinc oxide whisker and a polyimide coating layer coated on the outside of the nano titanium dioxide / tetrapodal zinc oxide whisker. The nano titanium dioxide / tetrapodal zinc oxide whisker composite material comprises tetrapodal zinc oxide whisker and nano titanium dioxide supported on the surface of the tetrapodal zinc oxide whisker. The polyimide coating layer is obtained by polymerizing 4,4-diaminodiphenyl ether and pyromellitic acid anhydride to obtain polyamic acid and then undergoing imidization.

3. The plastic film for packaging medical nonwoven fabrics according to claim 1 or 2, characterized in that: The preparation method of the polyimide-coated nano-titanium dioxide / tetrapod-shaped zinc oxide whisker composite material comprises the following steps: 1) placing a tetrapod-shaped zinc oxide crystal water dispersion in a reactor, and then slowly adding a titanium tetrachloride aqueous solution while stirring the tetrapod-shaped zinc oxide crystal water dispersion, after the addition is complete, closing the reactor, heating to 100-105° C. and continuing to stir and react for 3-6 hours, then cooling to room temperature, filtering, washing with water, and vacuum drying to obtain the nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material; 2) Add nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material to N,N-dimethylacetamide, add 4,4-diaminodiphenyl ether under ultrasonic stirring conditions, and after complete dissolution, add pyromellitic anhydride in 3 to 4 portions, and after complete dissolution, stir and react at 5 to 8° C. for 3 to 5 hours, centrifuge the obtained suspension, imide the obtained precipitate, and grind it to obtain the polyimide-coated nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material.

4. The plastic film for packaging medical nonwoven fabrics according to claim 3, characterized in that: The preparation method of the tetra-needle zinc oxide crystal water dispersion comprises the following steps: by weight, 2 to 3.5 parts of tetra-needle zinc oxide whiskers are placed in 100 parts of deionized water, and then 0.1 to 0.5 parts of tetradecyl dimethyl amine oxide are added, and the mixture is stirred and dispersed, and then ultrasonically treated to obtain the tetra-needle zinc oxide crystal water dispersion; the preparation method of the titanium tetrachloride aqueous solution comprises the following steps: in an ice-water bath, 0.2 to 0.5 parts of titanium tetrachloride are added to 20 to 30 parts of deionized water to prepare the titanium tetrachloride aqueous solution.

5. The plastic film for packaging medical nonwoven fabrics according to claim 3, characterized in that: When preparing the polyimide coated nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material, the molar ratio of 4,4-diaminodiphenyl ether to pyromellitic acid anhydride is 1:1.00-1.05; the added amount of the nano titanium dioxide / tetrapod-shaped zinc oxide whisker composite material is 35-55% of the total mass of 4,4-diaminodiphenyl ether and pyromellitic acid anhydride.

6. The plastic film for packaging medical nonwoven fabrics according to claim 1, characterized in that: The preparation method of the modified diatomite comprises the following steps: Calculated by weight, 10 parts of diatomaceous earth and 0.5-1 part of nano starch are added to 100 parts of water, and the mixture is fully mixed and filtered; the obtained filter cake is vacuum dried, and then heated to 600-650° C. at a heating rate of 2-6° C. / min in an air atmosphere for calcination, and the temperature is kept for 1.5-2 hours; after cooling to room temperature, the mixture is ground and passed through a 400-mesh sieve to obtain pretreated diatomaceous earth; the pretreated diatomaceous earth is placed in a silane coupling agent solution, stirred at a speed of more than 600 r / min for 60-90 minutes, and then ultrasonically treated for 60-90 minutes, and then filtered, washed with water, and vacuum dried to obtain the modified diatomaceous earth.

7. The plastic film for packaging medical nonwoven fabrics according to claim 1, characterized in that: The thickness ratio of the polyimide layer, the ethylene-vinyl alcohol copolymer layer and the polypropylene layer is 25-35:20-30:30-40; the polyimide layer and the ethylene-vinyl alcohol copolymer layer, and the ethylene-vinyl alcohol copolymer layer and the polypropylene layer are connected by an adhesive layer, and the adhesive used in the adhesive layer is a polyurethane adhesive.

8. The plastic film for packaging medical nonwoven fabrics according to claim 1, characterized in that: The preparation method of the polyimide layer comprises the following steps: using 4,4-diaminodiphenyl ether as a diamine monomer and pyromellitic acid dianhydride as a dianhydride monomer, copolymerizing in N,N-dimethylacetamide to obtain a polyamic acid mixed solution; adding a polyimide-coated nano titanium dioxide / tetra-needle zinc oxide whisker composite material and modified diatomaceous earth to the polyamic acid mixed solution, stirring and simultaneously performing ultrasonic dispersion, coating the obtained mixed solution after vacuum degassing and performing solvent removal treatment to obtain a polyamic acid film, and imidizing the polyamic acid film to obtain the polyimide layer.

9. The plastic film for packaging medical nonwoven fabrics according to claim 8, characterized in that: When preparing the polyimide layer, the added amount of the N,N-dimethylacetamide is 6 to 8 times the total mass of 4,4-diaminodiphenyl ether and pyromellitic dianhydride.

10. The method for preparing a plastic film for packaging medical nonwoven fabrics according to any one of claims 1 to 9, characterized in that: The following steps are involved: An adhesive is coated on the side of the polyimide layer facing the ethylene-vinyl alcohol copolymer layer, and then bonded with the ethylene-vinyl alcohol copolymer layer, and then placed in a compounding machine for compounding to obtain an intermediate composite layer; an adhesive is then coated on the side of the intermediate composite layer facing the polypropylene layer, and bonded with the polypropylene layer, and then placed in a compounding machine for compounding to obtain the plastic film for packaging medical non-woven fabrics.