Puncture resistant blown film and method of making same
By using a three-layer composite structure and hydrogen bonding, the problem of insufficient puncture resistance in traditional plastic packaging bags is solved, achieving high puncture resistance and ductility, and enhancing the overall performance of the film.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- GUIZHOU HUALI IND CO LTD
- Filing Date
- 2024-06-19
- Publication Date
- 2026-06-30
AI Technical Summary
Traditional plastic packaging bags are easily punctured when packaging sharp or hard items, and they degrade due to oxidation in high temperature or high humidity environments, resulting in insufficient puncture resistance and affecting their service life.
The puncture-resistant blown film adopts a three-layer composite structure. The outer layer is composed of high-density polyethylene and metallocene medium-density polyethylene. The middle layer contains linear low-density metallocene polyethylene, chitosan, low-density polyethylene, polyolefin elastomer and modified glass fiber. The inner layer is composed of low-density polyethylene and linear low-density metallocene polyethylene. The interlayer bonding force is enhanced by hydrogen bonding, and the introduction of modified glass fiber improves the strength and toughness.
It significantly improves the puncture resistance, ductility and impact resistance of the film, enhances interlayer bonding, and improves the abrasion resistance and service life of the film.
Smart Images
Figure SMS_1
Abstract
Description
Technical Field
[0001] This invention relates to the field of blow molding technology, specifically to a puncture-resistant blown film and its preparation method. Background Technology
[0002] Traditional product packaging bags are mainly made of PE and PP materials. These types of packaging bags generally utilize the good chemical resistance and insulation properties of plastic film, giving them good acid and alkali resistance and sealing performance. However, for some special product packaging, such as products with sharp and hard outer corners, traditional plastic packaging is easily punctured from the inside. For products containing powder, traditional plastic packaging is easily punctured from the outside, causing the product to scatter and be difficult to collect.
[0003] Based on the above, in the prior art, patent publication number CN102501513B discloses a heavy-duty packaging composite film, which consists of an outer layer, a core layer, and an inner layer; the outer layer is composed of metallocene linear polyethylene and low-density polyethylene; the core layer is composed of EVA and low-density polyethylene; and the inner layer is composed of metallocene linear polyethylene and low-density polyethylene. The metallocene linear polyethylene, EVA, and medium-density polyethylene in the composite film work synergistically to give the composite film good puncture resistance and tensile strength.
[0004] However, the composite films described in the aforementioned patents still have some shortcomings when considered in practice. One issue is insufficient puncture resistance. In the composite film structure, the core layer, composed of EVA and low-density polyethylene, is the main stress-bearing layer for puncture resistance. While EVA and low-density polyethylene possess a certain degree of elasticity and toughness, their puncture resistance still needs improvement when faced with sharp or hard objects. Especially when the packaging contains sharp or hard products, such as metal parts or glassware, the puncture resistance of EVA may not meet the actual requirements, leading to easy punctures, product damage, or leakage. Furthermore, although EVA constitutes a large proportion of the composite film, it is prone to oxidative degradation under high temperature or high humidity environments, which may further weaken its puncture resistance and affect the service life of the packaging. Summary of the Invention
[0005] To address the technical deficiencies in the prior art, this invention proposes a puncture-resistant blown film and its preparation method, solving the aforementioned technical problems and meeting practical needs. The specific technical solution is as follows:
[0006] A puncture-resistant blown film, wherein the puncture-resistant blown film has a three-layer composite structure, comprising an outer layer, a middle layer and an inner layer;
[0007] The outer layer is composed of the following raw materials by weight: 40-50 parts high-density polyethylene, 45-50 parts metallocene medium-density polyethylene, and 10-15 parts polyvinyl alcohol.
[0008] The raw material composition of the intermediate layer, by weight parts, is: 40-50 parts linear low-density metallocene polyethylene, 15-20 parts chitosan, 40-50 parts low-density polyethylene, 30-50 parts polyolefin elastomer, and 5-10 parts modified glass fiber.
[0009] The raw material composition of the inner layer, by weight, is: 40-50 parts of low-density polyethylene and 45-50 parts of linear low-density metallocene polyethylene.
[0010] Furthermore, the modified glass fiber is prepared by a silane coupling agent and glass fiber, wherein the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane, and the glass fiber has a length of 80-100 micrometers and a diameter of 3-15 micrometers.
[0011] Further, in the outer layer, the high-density polyethylene has a density of 0.95–0.965 g / cm³ and a melting point of 130–135°C; the metallocene medium-density polyethylene has a density of 0.91–0.93 g / cm³ and a melting point of 190–230°C; and the polyvinyl alcohol has a molecular weight of 60,000–70,000. In the middle layer, the linear low-density metallocene polyethylene has a density of 0.91–0.92 g / cm³. 3 The melting point is 110–120°C, the molecular weight of the chitosan is 80,000–100,000, and the density of the low-density polyethylene is 0.90–0.91 g / cm³. 3 The melting point is 105–110℃, and the density of the polyolefin elastomer is 0.81–0.85 g / cm³. 3 The melting point is 90–95°C; in the inner layer, the low-density polyethylene has a content of 0.90–0.91 g / cm³. 3 The linear low-density metallocene polyethylene has a melting point of 105–110°C and a density of 0.91–0.92 g / cm³. 3 Its melting point is 110-120℃.
[0012] Furthermore, the outer layer has a thickness of 0.03–0.04 mm, the middle layer has a thickness of 0.04–0.07 mm, and the inner layer has a thickness of 0.03–0.04 mm.
[0013] A method for manufacturing a puncture-resistant blown film includes the following steps:
[0014] S1. Add the weighed silane coupling agent to an aqueous methanol solution, stir to dissolve, then add the weighed glass fiber, and continue stirring to allow the silane coupling agent to react with the glass fiber to obtain modified glass fiber.
[0015] S2. Weigh the linear low-density metallocene polyethylene, chitosan, low-density polyethylene, polyolefin elastomer, and modified glass fiber, mix them evenly, and then pour them into the intermediate layer film screw extruder for mixing to obtain the molten intermediate layer masterbatch.
[0016] S3. Mix high-density polyethylene, metallocene medium-density polyethylene, and polyvinyl alcohol evenly, then pour the mixture into an outer film screw extruder for compounding to obtain a molten outer layer masterbatch.
[0017] S4. Mix low-density polyethylene and linear low-density metallocene polyethylene evenly, and then pour the mixture into a screw extruder for inner layer film mixing to obtain molten inner layer masterbatch.
[0018] S5. The molten outer layer masterbatch, middle layer masterbatch and inner layer masterbatch are extruded into the die head of the same three-layer co-extrusion blown film machine and fused together. They are then extruded in a tubular shape through the die orifice and blown into shape. The film is then cooled and shaped under the action of the cooling air ring by the traction machine to obtain a puncture-resistant film.
[0019] Further, in step S3, the screw temperature of the outer layer film screw extruder is 190-210°C; in step S2, the screw temperature of the middle layer film screw extruder is 160-165°C; and in step S4, the screw temperature of the inner layer film screw extruder is 120-165°C.
[0020] Furthermore, the screw speeds of the outer layer film screw extruder, the middle layer film screw extruder, and the inner layer film screw extruder are all 10–40 r / min, and the extrusion processing pressures are all 20–40 MPa.
[0021] Further, in step S1, methanol and deionized water are mixed using a stirrer, and then a silane coupling agent is added. The stirring speed is 250-300 rpm, and the stirring time is 15-30 min to obtain a methanol solution of the silane coupling agent. Glass fiber is added to the methanol solution of the silane coupling agent, and a second stirring is performed using a stirrer at a speed of 450-500 rpm for 30-40 min. Then, the glass fiber is filtered, washed, and dried to obtain modified glass fiber. The weight percentages of the above components are: 1% silane coupling agent, 76% methanol, 8% deionized water, and 15% glass fiber.
[0022] The beneficial effects of this invention are as follows:
[0023] The synergistic combination of raw materials in the three-layer structure of this invention gives the film excellent puncture resistance, ductility, and impact resistance. The outer layer of high-density polyethylene and metallocene medium-density polyethylene provides the film with good abrasion resistance and weather resistance, while also increasing its puncture resistance to a certain extent. The middle layer of linear low-density metallocene polyethylene, low-density polyethylene, polyolefin elastomer, and modified glass fiber works synergistically to improve the film's strength and toughness. The modified glass fiber in the middle layer, as a reinforcing material, significantly improves the film's puncture resistance. The inner layer of low-density polyethylene and linear low-density metallocene polyethylene work together to give the film good ductility. Detailed Implementation
[0024] The embodiments of the present invention will be described below with reference to relevant examples. The embodiments of the present invention are not limited to the following examples, and the present invention relates to relevant necessary components in this technical field, which should be regarded as well-known technology in this technical field and can be known and mastered by those skilled in this technical field.
[0025] A puncture-resistant blown film, wherein the puncture-resistant blown film has a three-layer composite structure, comprising an outer layer, a middle layer and an inner layer;
[0026] The outer layer is composed of the following raw materials by weight: 40-50 parts high-density polyethylene, 45-50 parts metallocene medium-density polyethylene, and 10-15 parts polyvinyl alcohol.
[0027] The raw material composition of the intermediate layer, by weight parts, is: 40-50 parts linear low-density metallocene polyethylene, 15-20 parts chitosan, 40-50 parts low-density polyethylene, 30-50 parts polyolefin elastomer, and 5-10 parts modified glass fiber.
[0028] The raw material composition of the inner layer, by weight, is: 40-50 parts of low-density polyethylene and 45-50 parts of linear low-density metallocene polyethylene.
[0029] The film of this invention has a three-layer composite structure, consisting of an outer layer, a middle layer, and an inner layer, which are co-extruded and hot-pressed together. The outer layer is in direct contact with the external environment and needs to provide the film with abrasion resistance, weather resistance, and chemical stability. The outer layer is composed of high-density polyethylene and metallocene medium-density polyethylene. High-density polyethylene provides good abrasion resistance and weather resistance, while metallocene medium-density polyethylene enhances the strength and toughness of the film, increasing its puncture resistance. The middle layer includes linear low-density metallocene polyethylene, chitosan, low-density polyethylene, polyolefin elastomer, and modified glass fiber, etc. The composition consists of linear low-density metallocene polyethylene and low-density polyethylene, which provide basic strength and toughness. Polyolefin elastomers improve the elasticity and impact resistance of the film. Modified glass fiber, as a reinforcing material, can improve the puncture resistance of the film. Chitosan can increase the bonding ability between the middle layer and the outer layer through hydrogen bonding, while also giving the film a certain degree of biodegradability. The inner layer is composed of low-density polyethylene and linear low-density metallocene polyethylene, which gives the film good ductility and flexibility, thus giving the film good environmental stress resistance and further increasing the film's puncture resistance.
[0030] The outer layer uses high-density polyethylene and metallocene medium-density polyethylene, while the middle layer uses linear low-density metallocene polyethylene and low-density polyethylene. These differences in molecular structure, density, and physical properties result in insufficient bonding between the middle and outer layers during blown film production, leading to more pronounced layer boundaries in the microstructure. This makes the film prone to delamination during prolonged use. This invention introduces chitosan into the middle layer and polyvinyl alcohol into the outer layer. Hydrogen bonds are formed between the hydroxyl groups of chitosan and polyvinyl alcohol, increasing the bonding strength between the middle and outer layers, enhancing the integrity of the film structure, and making the film more durable. The tighter bond between the middle and outer layers through hydrogen bonds strengthens the interlayer bonding of the entire film. This enhanced interlayer bonding allows the film to resist puncture more effectively under external puncture forces, thus improving puncture resistance. The formation of hydrogen bonds not only strengthens the interlayer bonding but also helps optimize the mechanical properties of the film. Through hydrogen bonding, chitosan can better transfer and disperse stress under external and internal forces, thereby improving the strength and toughness of the film.
[0031] In one preferred embodiment of the present invention, the modified glass fiber is prepared by a silane coupling agent and glass fiber, wherein the silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane, and the glass fiber has a length of 80-100 micrometers and a diameter of 3-15 micrometers.
[0032] When γ-methacryloyloxypropyltrimethoxysilane is applied to the surface treatment of glass fibers, the hydrolyzable groups in its molecule hydrolyze in water to form reactive polyhydroxysilanols. These polyhydroxysilanols then undergo a dehydration condensation reaction with the hydroxyl groups on the glass fiber surface to generate stable silicon-oxygen bonds, achieving a strong bond between the silane coupling agent and the glass fiber. Simultaneously, the other end of the silane coupling agent (methacryloyloxy group) is an organic affinity end, thereby improving the compatibility between the glass fiber and the interlayer material system. This increases the bonding strength between the glass fiber and the interlayer and also enhances the overall puncture resistance of the interlayer.
[0033] The length and diameter of glass fibers are important factors affecting their bonding effect with the interlayer. Within the specified range (length 80-100 micrometers, diameter 3-15 micrometers), the moderate length of the glass fibers enables them to form an effective reinforcing network in the interlayer. At the same time, the glass fibers have a high specific surface area, which is conducive to the reaction of silane coupling agents on their surface, further improving the compatibility with the interlayer. In the interlayer, glass fibers act as a reinforcing phase. Glass fibers with a length of 80-100 micrometers can form a uniform distribution and an effective reinforcing network in the interlayer, thereby significantly improving the puncture resistance of the composite material.
[0034] In one preferred embodiment of the present invention, in the outer layer, the high-density polyethylene has a density of 0.95–0.965 g / cm³ and a melting point of 130–135°C; the metallocene medium-density polyethylene has a density of 0.91–0.93 g / cm³ and a melting point of 190–230°C; and the polyvinyl alcohol has a molecular weight of 60,000–70,000. In the middle layer, the linear low-density metallocene polyethylene has a density of 0.91–0.92 g / cm³. 3 The melting point is 110–120°C, the molecular weight of the chitosan is 80,000–100,000, and the low-density polyethylene has a molecular weight of 0.90–0.91 g / cm³. 3 The melting point is 105–110℃, and the density of the polyolefin elastomer is 0.81–0.85 g / cm³. 3 The melting point is 90–95°C; in the inner layer, the density of the low-density polyethylene is 0.90–0.91 g / cm³. 3 The linear low-density metallocene polyethylene has a melting point of 105–110°C and a density of 0.91–0.92 g / cm³. 3 Its melting point is 110-120℃.
[0035] Specifically, in the outer layer, the density of high-density polyethylene is 0.95 g / cm³. 3 The melting point is 130℃, and the density of metallocene medium-density polyethylene is 0.91 g / cm³. 3The melting point is 190℃, and the molecular weight of polyvinyl alcohol is 60,000; in the intermediate layer, the density of linear low-density metallocene polyethylene is 0.91 g / cm³. 3 The melting point is 120℃, the molecular weight of chitosan is 80,000, and the density of low-density polyethylene is 0.90 g / cm³. 3 The melting point is 105℃, and the density of the polyolefin elastomer is 0.85 g / cm³. 3 The melting point is 95℃; in the inner layer, the low-density polyethylene content is 0.90 g / cm³. 3 The melting point is 105℃, and the density of linear low-density metallocene polyethylene is 0.92 g / cm³. 3 Its melting point is 120℃.
[0036] In one preferred embodiment of the present invention, the thickness of the outer layer is 0.03-0.04 mm, the thickness of the middle layer is 0.04-0.07 mm, and the thickness of the inner layer is 0.03-0.04 mm. Specifically, the thickness of the outer layer is 0.03 mm, the thickness of the middle layer is 0.06 mm, and the thickness of the inner layer is 0.03 mm.
[0037] A method for manufacturing a puncture-resistant blown film includes the following steps:
[0038] S1. Add the weighed silane coupling agent to an aqueous methanol solution, stir to dissolve, then add the weighed glass fiber, and continue stirring to allow the silane coupling agent to react with the glass fiber to obtain modified glass fiber.
[0039] S2. Weigh the linear low-density metallocene polyethylene, chitosan, low-density polyethylene, polyolefin elastomer, and modified glass fiber, mix them evenly, and then pour them into the intermediate layer film screw extruder for mixing to obtain the molten intermediate layer masterbatch.
[0040] S3. Mix high-density polyethylene, metallocene medium-density polyethylene, and polyvinyl alcohol evenly, then pour the mixture into an outer film screw extruder for compounding to obtain a molten outer layer masterbatch.
[0041] S4. Mix low-density polyethylene and linear low-density metallocene polyethylene evenly, and then pour the mixture into a screw extruder for inner layer film mixing to obtain molten inner layer masterbatch.
[0042] S5. The molten outer layer masterbatch, middle layer masterbatch and inner layer masterbatch are extruded into the die head of the same three-layer co-extrusion blown film machine and fused together. They are then extruded in a tubular shape through the die orifice and blown into shape. The film is then cooled and shaped under the action of the cooling air ring by the traction machine to obtain a puncture-resistant film.
[0043] In one preferred embodiment of the present invention, in step S3, the screw temperature of the outer film screw extruder is 190-210°C; in step S2, the screw temperature of the middle film screw extruder is 160-165°C; and in step S4, the screw temperature of the inner film screw extruder is 120-165°C. Specifically, the screw temperature of the outer film screw extruder is 200°C, the screw temperature of the middle film screw extruder is 165°C, and the screw temperature of the inner film screw extruder is 150°C.
[0044] In one preferred embodiment of the present invention, the screw speeds of the outer layer film screw extruder, the middle layer film screw extruder, and the inner layer film screw extruder are all 10–40 r / min, and the extrusion processing pressures are all 20–40 MPa. Specifically, the screw speed of the outer layer film screw extruder is 10 r / min, and the extrusion processing pressure is 40 MPa; the screw speed of the middle layer film screw extruder is 30 r / min, and the extrusion processing pressure is 20 MPa; and the screw speed of the inner layer film screw extruder is 20 r / min, and the extrusion processing pressure is 20 MPa.
[0045] In one preferred embodiment of the present invention, in step S1, methanol and deionized water are mixed using a stirrer, and then a silane coupling agent is added. The stirring speed is 250-300 rpm, and the stirring time is 15-30 min to obtain a methanol solution of the silane coupling agent. Glass fiber is added to the methanol solution of the silane coupling agent, and a second stirring is performed using a stirrer at a speed of 450-500 rpm for 30-40 min. Then, the glass fiber is filtered, washed, and dried to obtain modified glass fiber. The weight percentages of the above components are: 1% silane coupling agent, 76% methanol, 8% deionized water, and 15% glass fiber.
[0046] The preferred silane coupling agent of this invention is γ-methacryloyloxypropyltrimethoxysilane, which increases the compatibility between glass fiber and interlayer material, allowing the modified glass fiber to be uniformly dispersed in the interlayer. The silane coupling agent contains one methacrylate group and three methoxysilyl groups. Some of the methoxysilyl groups in the silane coupling agent are organic affinity groups, while the other part of the methoxysilyl groups react chemically with functional groups such as hydroxyl (-OH) on the surface of the glass fiber to form Si-O-Si chemical bonds. This allows the silane coupling agent to be loaded onto the surface of the glass fiber. Through the organic affinity groups of the silane coupling agent, the glass fiber changes from being incompatible with organic materials to being compatible, thus increasing the compatibility between the glass fiber and the interlayer material.
[0047] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
[0048] Example 1
[0049] 1.0 g of silane coupling agent was weighed and added to a methanol-water solution prepared from 76.0 g of methanol and 8.0 g of deionized water. The mixture was stirred at 300 rpm for 15 min to dissolve the silane coupling agent. Then, 15.0 g of glass fiber was added and the mixture was stirred at 500 rpm for 30 min to allow the silane coupling agent to react with the glass fiber. The glass fiber was then filtered and separated, washed with 300 ml of methanol, and dried in an oven to obtain modified glass fiber.
[0050] Weigh out 50 parts of linear low-density metallocene polyethylene, 15 parts of chitosan, 50 parts of low-density polyethylene, 30 parts of polyolefin elastomer, and 5 parts of modified glass fiber, mix them evenly, and then pour them into the intermediate layer film screw extruder. Set the screw temperature of the outer layer film screw extruder to 200℃, and then knead them to obtain the molten intermediate layer masterbatch.
[0051] 40 parts of high-density polyethylene, 50 parts of metallocene medium-density polyethylene, and 15 parts of polyvinyl alcohol were weighed and mixed evenly, and then poured into the outer layer film screw extruder. The screw temperature of the middle layer film screw extruder was set to 165°C, and then the mixture was kneaded to obtain the outer layer masterbatch in a molten state.
[0052] 50 parts of low-density polyethylene and 50 parts of linear low-density metallocene polyethylene were weighed and mixed evenly, and then poured into the screw extruder of the inner layer film. The screw temperature of the inner layer film screw extruder was set to 150°C, and then the mixture was kneaded to obtain the molten inner layer masterbatch.
[0053] The molten outer layer masterbatch, middle layer masterbatch, and inner layer masterbatch are extruded into the same die of a three-layer co-extrusion blown film mill and extruded in a tubular shape through the die orifice. The film is blown and tractioned by a traction machine. By controlling the feeding speed of the outer, middle, and inner layer extruders and the traction speed of the traction machine, the thickness of each film layer is controlled. The film is cooled and shaped under the action of a cooling air ring, resulting in a puncture-resistant film with an outer layer thickness of 0.03 mm, a middle layer thickness of 0.06 mm, and an inner layer thickness of 0.03 mm.
[0054] Comparative Example 1
[0055] The difference between Comparative Example 1 and Example 1 is that the modified glass fiber added in Comparative Example 1 is 7 parts by weight, while the other components and preparation steps are the same as in Example 1.
[0056] Comparative Example 2
[0057] The difference between Comparative Example 2 and Example 1 is that no modified glass fiber is added in Comparative Example 2, while the other components and preparation steps are the same as in Example 1.
[0058] Comparative Example 3
[0059] The difference between Comparative Example 2 and Example 1 is that in Comparative Example 3, the modified glass fiber was replaced with an equal amount of unmodified glass fiber, while the other components and preparation steps were the same as in Example 1.
[0060] The films prepared in Example 1 and Comparative Examples 1-3 were tested for elongation at break (%), tensile strength (MPa), transverse tear strength (kN / m), longitudinal tear strength (kN / m), and puncture resistance (N / 12mm). The results are shown in the table below:
[0061]
[0062] Compared to Comparative Example 2 (without modified glass fiber), Example 1 (with 5 parts modified glass fiber) showed significantly improved performance in all tested parameters (elongation at break, tensile strength, transverse tear strength, longitudinal tear strength, and puncture resistance). This indicates that the addition of modified glass fiber has a significant effect on improving the overall performance of the film.
[0063] Compared to Comparative Example 1 (7 parts modified glass fiber), Example 1 (with 5 parts modified glass fiber) showed increased elongation at break, tensile strength (transverse, tear strength, longitudinal tear strength), and puncture resistance. This indicates that the addition of modified glass fiber effectively increases the puncture resistance and toughness of the film. Compared to Comparative Example 3 (with an equal amount of unmodified glass fiber), Example 1 (with 5 parts modified glass fiber) performed better in all tested performance indicators. This demonstrates that the modification treatment of glass fiber by the silane coupling agent is effective, significantly improving the compatibility and interfacial strength between the glass fiber and the polymer matrix, thereby improving the overall performance of the film. The puncture resistance of Example 1 (76.5 N / 12 mm) was significantly higher than that of Comparative Example 2 (without modified glass fiber) (39.7 N / 12 mm), further verifying the key role of modified glass fiber in improving the puncture resistance of the film.
[0064] The above description is only a preferred embodiment of the present invention. It should be noted that those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.
Claims
1. A puncture-resistant blown film, wherein the puncture-resistant blown film has a three-layer composite structure, comprising an outer layer, a middle layer, and an inner layer, characterized in that, The outer layer is composed of the following raw materials by weight: 40-50 parts high-density polyethylene, 45-50 parts metallocene medium-density polyethylene, and 10-15 parts polyvinyl alcohol. The raw material composition of the intermediate layer, by weight parts, is: 40-50 parts linear low-density metallocene polyethylene, 15-20 parts chitosan, 40-50 parts low-density polyethylene, 30-50 parts polyolefin elastomer, and 5-10 parts modified glass fiber. The raw material composition of the inner layer, by weight, is: 40-50 parts of low-density polyethylene and 45-50 parts of linear low-density metallocene polyethylene. The modified glass fiber is prepared by using a silane coupling agent and glass fiber. The silane coupling agent is γ-methacryloyloxypropyltrimethoxysilane. The glass fiber has a length of 80-100 micrometers and a diameter of 3-15 micrometers.
2. The puncture-resistant blown film according to claim 1, characterized in that, In the outer layer, the density of the high-density polyethylene is 0.95–0.965 g / cm³. 3 The melting point is 130–135°C, and the density of the metallocene medium-density polyethylene is 0.91–0.93 g / cm³. 3 The melting point is 190-230℃, and the molecular weight of the polyvinyl alcohol is 60,000-70,000; In the intermediate layer, the linear low-density metallocene polyethylene has a density of 0.91–0.92 g / cm³. 3 The melting point is 110–120°C, the molecular weight of the chitosan is 80,000–100,000, and the density of the low-density polyethylene is 0.90–0.91 g / cm³. 3 The melting point is 105–110℃, and the density of the polyolefin elastomer is 0.81–0.85 g / cm³. 3 Its melting point is 90–95℃; In the inner layer, the low-density polyethylene has a density of 0.90–0.91 g / cm³. 3 The linear low-density metallocene polyethylene has a melting point of 105–110°C and a density of 0.91–0.92 g / cm³. 3 Its melting point is 110-120℃.
3. The puncture-resistant blown film according to claim 1, characterized in that, The outer layer has a thickness of 0.03–0.04 mm, the middle layer has a thickness of 0.04–0.07 mm, and the inner layer has a thickness of 0.03–0.04 mm.
4. A method for manufacturing a puncture-resistant blown film as described in any one of claims 1 to 3, characterized in that, Includes the following steps: S1. Add the weighed silane coupling agent to an aqueous methanol solution, stir to dissolve, then add the weighed glass fiber, and continue stirring to allow the silane coupling agent to react with the glass fiber to obtain modified glass fiber. S2. Weigh the linear low-density metallocene polyethylene, chitosan, low-density polyethylene, polyolefin elastomer, and modified glass fiber, mix them evenly, and then pour them into the intermediate layer film screw extruder for mixing to obtain the molten intermediate layer masterbatch. S3. Mix high-density polyethylene, metallocene medium-density polyethylene, and polyvinyl alcohol evenly, then pour the mixture into an outer film screw extruder for compounding to obtain a molten outer layer masterbatch. S4. Mix low-density polyethylene and linear low-density metallocene polyethylene evenly, then pour the mixture into an inner layer film screw extruder for compounding to obtain a molten inner layer masterbatch. S5. The molten outer layer masterbatch, middle layer masterbatch and inner layer masterbatch are extruded into the die head of the same three-layer co-extrusion blown film machine and fused together. They are then extruded in a tubular shape through the die orifice and blown into shape. The film is then cooled and shaped under the action of the cooling air ring by the traction machine to obtain a puncture-resistant film. In step S1, methanol and deionized water are mixed using a stirrer, and then a silane coupling agent is added. The stirring speed is 250-300 rpm, and the stirring time is 15-30 min to obtain a methanol solution of the silane coupling agent. Glass fiber is added to the methanol solution of the silane coupling agent, and a second stirring is performed using a stirrer at a speed of 450-500 rpm for 30-40 min. Then, the glass fiber is filtered, washed, and dried to obtain modified glass fiber. The weight percentages of the above components are: 1% silane coupling agent, 76% methanol, 8% deionized water, and 15% glass fiber.
5. The method for manufacturing a puncture-resistant blown film according to claim 4, characterized in that, In step S3, the screw temperature of the outer film screw extruder is 190-210℃; in step S2, the screw temperature of the middle film screw extruder is 160-165℃; and in step S4, the screw temperature of the inner film screw extruder is 120-165℃.
6. The method for manufacturing a puncture-resistant blown film according to claim 4, characterized in that, The screw speeds of the outer layer film screw extruder, the middle layer film screw extruder, and the inner layer film screw extruder are all 10–40 r / min, and the extrusion processing pressures are all 20–40 MPa.