Environment-friendly composite biaxial stretching film and preparation method thereof

Abstract

The application discloses an environment-friendly composite biaxial stretching film and a preparation method thereof. The formula comprises polypropylene, an antistatic agent, a slip agent, maleic anhydride grafted PP, maleic anhydride grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, carbon five petroleum resin, copolymer anti-blocking agent and homopolymer high slip anti-blocking agent. The preparation method comprises the following steps: raw material proportioning, melt extrusion, extrusion casting, longitudinal stretching, transverse stretching, traction edge cutting, winding and storage, aging treatment and product slitting. The surface layer 1 is replaced by maleic anhydride grafted PP, maleic anhydride grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, carbon five petroleum resin and copolymer anti-blocking agent, and the surface layer 2 is replaced by polypropylene and homopolymer high slip anti-blocking agent. The base material can be directly compounded with other materials under appropriate temperature and appropriate pressure, the environmental pollution generated during the processing of the biaxial stretching film product is reduced, and the energy loss is also reduced.

Description

Technical Field

[0001] This invention relates to the field of heat-sealing film technology, specifically to an environmentally friendly composite biaxially oriented film and its preparation method. Background Technology

[0002] BOPP is short for "Biaxially Oriented Polypropylene," which refers to biaxially oriented polypropylene film. Its production involves first passing molten polypropylene through a narrow die head to form sheets or thick films, then stretching them simultaneously or in stages in two perpendicular directions (longitudinal and transverse) at specific temperatures and speeds in a dedicated stretching machine. The resulting film undergoes appropriate cooling or heat treatment, or special processing (such as corona treatment or coating).

[0003] Traditional pre-coating film processing involves coating a layer of polyethyleneimine aqueous solution onto the surface of ordinary BOPP film, drying it, extruding and coating a layer of EVA hot melt adhesive onto the film, and then laminating it with paper to form a paper-plastic composite product. As disclosed in patent number CN116063933A, "A method for producing an anti-stick BOPP pre-coated film," the BOPP pre-coated film specifically includes a base layer, a primer layer, and a hot melt adhesive layer arranged sequentially from bottom to top. The base layer is composed of PP, PTFE, and silicone oil; the primer layer is composed of polyethyleneimine aqueous solution and alcohol; and the hot melt adhesive layer is an ethylene-vinyl acetate copolymer. The document also indicates that a hot melt adhesive layer is laminated onto the surface of the primer layer, followed by cooling and setting. The primer layer is composed of polyethyleneimine aqueous solution and alcohol. While this process can improve the special properties of BOPP film, this processing method is prone to environmental pollution in the coating and EVA coating steps, and also increases energy consumption and costs. To reduce these two processes and overcome the aforementioned problems, we have made functional improvements to the surface layer of the BOPP film base, and proposed an environmentally friendly composite biaxially oriented film and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide an environmentally friendly composite biaxially oriented film and its preparation method, so as to solve the problems mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution: an environmentally friendly composite biaxially oriented film, the formulation of which includes polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, ethylene-octene copolymer, maleic anhydride-grafted EVA, ethylene-butene copolymer, C5 petroleum resin, copolymer antiblocking agent, and homopolymer high slip antiblocking agent.

[0006] The main ingredients are polypropylene, antistatic agent and slip agent, and the mass percentages of each component are as follows: 96% to 99.5% polypropylene, 0.5% to 1.5% antistatic agent and 0.5% to 2.5% slip agent.

[0007] Among them, maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-butene copolymer, ethylene-octene copolymer, C5 petroleum resin and copolymer antiblocking agent are the first surface layer materials, and the mass percentages of each component are as follows: 1% to 5% maleic anhydride-grafted PP, 5% to 10% maleic anhydride-grafted EVA, 10% to 20% ethylene-butene copolymer, 30% to 50% ethylene-octene copolymer, 10% to 30% C5 petroleum resin and 1% to 10% copolymer antiblocking agent;

[0008] Among them, polypropylene and homopolymer high-slip antiblocking agent are the second surface layer materials, and the mass percentages of each component are: 90% to 99% polypropylene and 1% to 10% homopolymer high-slip antiblocking agent.

[0009] Preferably, the polypropylene is H3035, the antistatic agent is AS2235PP, the slip agent is S7220, the maleic anhydride-grafted PP is 18722, the ethylene-octene copolymer is FT810, the maleic anhydride-grafted EVA is 38E802, the ethylene-butene copolymer is FT411, the C5 petroleum resin is PZX-H2100, the copolymer antiblocking agent is AB05CPP, and the homopolymer high slip antiblocking agent is SAB16.

[0010] Preferably, the first surface material contains 5% maleic anhydride-grafted PP, 10% maleic anhydride-grafted EVA, 20% ethylene-butene copolymer, 36% ethylene-octene copolymer, 24% C5 petroleum resin, and 5% copolymer antiblocking agent.

[0011] A method for preparing an environmentally friendly composite biaxially oriented film includes the following steps: Step 2, melt extrusion; Step 3, extrusion casting; Step 4, longitudinal stretching; Step 5, transverse stretching; Step 6, traction trimming; Step 7, winding and storage; Step 8, aging treatment; and Step 9, slitting the finished product. The method is characterized by:

[0012] In step one above, raw materials are prepared according to the formula ratio and the raw materials are pretreated.

[0013] In step two above, the raw materials are melted and added to an extruder for extrusion;

[0014] In step three above, the molten raw material is extruded from the die and then shaped, cooled, and crystallized to form a sheet.

[0015] In step four above, the sheet is stretched longitudinally;

[0016] In step five above, the sheet is stretched laterally;

[0017] In step six above, the stretched sheet is subjected to traction, cooling, trimming, thickness measurement, and corona treatment.

[0018] In step seven above, the corona-treated sheet is rolled up and stored.

[0019] In step eight above, the sheet is aged after being stored and cooled.

[0020] In step nine above, the aged sheet is slit to obtain the finished product.

[0021] Preferably, in step one, dry and pure raw materials are selected, mixed evenly, and then polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, ethylene-octene copolymer, maleic anhydride-grafted EVA, ethylene-butene copolymer, C5 petroleum resin, copolymer anti-blocking agent, and homopolymer high slip anti-blocking agent are added to the main machine, auxiliary machine one, and auxiliary machine two. Auxiliary machine one contains maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-butene copolymer, ethylene-octene copolymer, C5 petroleum resin, and copolymer anti-blocking agent, while auxiliary machine two contains polypropylene and homopolymer high slip anti-blocking agent.

[0022] Preferably, in step two, the temperature of the main extruder is set to 240-250℃, the temperatures of auxiliary extruder one and auxiliary extruder two are set to 210-245℃, the speed of the main extruder is set to 70-90 rpm, the speed of auxiliary extruder one is set to 100-110 rpm, and the surface layer thickness is set to 3µm; the speed of auxiliary extruder two is set to 40-60 rpm, and the surface layer thickness is set to 1µm.

[0023] Preferably, in step three, after the extruder extrudes the molten raw material and filters it, the three layers of molten material are conveyed to the casting machine through the die head, and the casting is performed by an auxiliary traction device. The temperature of the quench roller in the casting machine is set to 36°C, and the temperature of the water tank is set to 35°C.

[0024] Preferably, in step four, longitudinal stretching is performed using a longitudinal stretching machine. The temperature of the preheating zone of the longitudinal stretching machine is set to 100-130℃, the temperature of the stretching zone is set to 85-111℃, and the temperature of the shaping zone is set to 110-140℃.

[0025] Preferably, in step five, the transverse stretching is performed using a transverse stretching machine. The temperature of the preheating zone of the transverse stretching machine is set to 160–170°C, and the air velocity of the circulating air in the preheating zone is 60%–90%. The temperature of the stretching zone is set to 150–160°C, and the air velocity of the circulating air in the stretching zone is 80%–90%. The temperature of the setting zone is set to 150–170°C, and the air velocity of the circulating air in the setting zone is 80%–90%. The air velocity in the upper cooling zone of the transverse stretching machine is set to 60%–95%, and the air velocity in the lower cooling zone is set to 50%–90%.

[0026] Preferably, in step six, the excess portion and burr edge portion of the stretched sheet are removed, and thickness is measured and single-sided corona treatment is performed. The output power of the corona treatment is 98kW and the corona value is 38 dynes or higher.

[0027] Preferably, in step seven, the sheet after traction and trimming is wound up and stored, with the winding tension set to 23%, the winding pressure set to 32%, the turning tension set to 135%, the film-breaking winding tension set to 14%, and the winding method being contact winding.

[0028] Compared with the prior art, the beneficial effects of this invention are as follows: This invention improves the functionality of the surface layer of the BOPP film base film by replacing surface layer 1 with maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-butene copolymer, ethylene-octene copolymer, C5 petroleum resin, and a copolymer anti-blocking agent; and replacing surface layer 2 with polypropylene and a homopolymer high-slip anti-blocking agent. Surface layer 1 serves as a functional layer, composed of six main materials. Through this compounded material, no coating is required in downstream processes; only appropriate heating and pressure are needed to laminate the substrate with paper to complete the paper-plastic composite product. Due to the special properties of the materials used, the processing requirements are quite stringent, requiring precise control of temperature, wind speed, and rotation speed.

[0029] In actual processing, production is carried out using the advanced German Bruckner three-layer co-extrusion production line. Raw materials are selected and batched, then melt-extruded separately through an extruder, collected at a die, and extruded into a casting system for casting. After being stretched more than 5 times longitudinally and then 9.2-9.7 times transversely, the film is trimmed and automatically thickness-measured by a traction system, finally being wound to form our semi-finished product. It then undergoes 48 hours of aging at 30-40 degrees Celsius, before being slit to the customer's required specifications by a slitting machine. After product inspection, it is packaged, weighed, and stored, completing the entire production process. The environmentally friendly composite biaxially oriented film produced by this invention replaces the traditional BOPP pre-coated base film, eliminating two coating processes: polyethyleneimine water and EVA hot melt adhesive, thus reducing the environmental pollution caused by these processes. Direct lamination can be achieved through surface functional modification, solving the environmental pollution problem caused by coatings, while significantly reducing coating costs, thus lowering costs and increasing revenue for downstream customers. Attached Figure Description

[0030] Figure 1 This is a flowchart of the method of the present invention. Detailed Implementation

[0031] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0032] Please see Figure 1 The present invention provides a technical solution:

[0033] Example 1

[0034] An environmentally friendly composite biaxially oriented film, the formulation of which includes polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, copolymer antiblocking agent, and homopolymer high-slip antiblocking agent; polypropylene, antistatic agent, and slip agent are core layer materials; maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, and copolymer antiblocking agent are first core layer materials; polypropylene and homopolymer high-slip antiblocking agent are second core layer materials. The specific mass percentages of each component are as follows: The main unit contains 98.10% polypropylene, 1.20% antistatic agent, and 0.70% slip agent; Auxiliary unit one contains 5% maleic anhydride-grafted PP, 10% maleic anhydride-grafted EVA, 20% ethylene-octene copolymer, 36% ethylene-butene copolymer, 24% C5 petroleum resin, and 5% copolymer anti-blocking agent; Auxiliary unit two contains 95% polypropylene and 5% homogenate. High-slip anti-blocking agent; wherein, polypropylene is H3035, antistatic agent is AS2235PP, slip agent is S7220, maleic anhydride-grafted PP is 18722, ethylene-octene copolymer is FT810, maleic anhydride-grafted EVA is 38E802, ethylene-butene copolymer is FT411, C5 petroleum resin is PZX-H2100, copolymer anti-blocking agent is AB05CPP, and homopolymer high-slip anti-blocking agent is SAB16.

[0035] A method for preparing an environmentally friendly composite biaxially oriented film includes the following steps: Step 1, raw material proportioning; Step 2, melt extrusion; Step 3, extrusion casting; Step 4, longitudinal stretching; Step 5, transverse stretching; Step 6, traction trimming; Step 7, winding and storage; Step 8, aging treatment; and Step 9, slitting of finished products.

[0036] In step one above, raw materials are prepared according to the formula ratio and pretreated. After being mixed evenly, polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, copolymer antiblocking agent, and homopolymer high slip antiblocking agent are added to the main machine, auxiliary machine one, and auxiliary machine two. Auxiliary machine one contains maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-butene copolymer, ethylene-octene copolymer, C5 petroleum resin, and copolymer antiblocking agent. Auxiliary machine two contains polypropylene and homopolymer high slip antiblocking agent.

[0037] In step two above, the raw material is melted and added to an extruder for extrusion. The temperature of the main extruder is set to 240-250℃, and the temperatures of auxiliary extruder one and auxiliary extruder two are set to 210-245℃. The speed of the main extruder is set to 70-90 rpm, the speed of auxiliary extruder one is set to 100-110 rpm, and the surface thickness is set to 3µm; the speed of auxiliary extruder two is set to 40-60 rpm, and the surface thickness is set to 1µm.

[0038] In step three above, after the extruded molten raw material is filtered, the three layers of molten material are conveyed to the casting machine through the die head, and the casting is performed by the auxiliary traction device. The temperature of the chilling roller in the casting machine is set to 36°C and the temperature of the water tank is set to 35°C.

[0039] In step four above, the sheet is longitudinally stretched by a longitudinal stretching machine. The temperature of the preheating zone of the longitudinal stretching machine is set to 100-130℃, the temperature of the stretching zone is set to 85-111℃, and the temperature of the shaping zone is set to 110-140℃.

[0040] In step five above, the sheet is stretched laterally using a transverse stretching machine. The preheating zone temperature of the transverse stretching machine is set to 160-170℃, and the circulating air velocity in the preheating zone is 60%-90%. The stretching zone temperature is set to 150-160℃, and the circulating air velocity in the stretching zone is 80%-90%. The setting zone temperature is set to 150-170℃, and the circulating air velocity in the setting zone is 80%-90%. The air velocity in the upper cooling zone of the transverse stretching machine is set to 60%-95%, and the air velocity in the lower cooling zone is set to 50%-90%.

[0041] In step six above, the stretched sheet is subjected to traction and edge trimming. The excess and burr edges of the stretched sheet are removed, and thickness is measured and single-sided corona treatment is performed. The output power of the corona treatment is 98kW and the corona value is above 38 dynes.

[0042] In step seven above, the sheet after trimming is wound up and stored. The winding tension is set to 23%, the winding pressure is set to 32%, the turning tension is set to 135%, the film breaking winding tension is set to 14%, and the winding method is contact winding.

[0043] In step eight above, the sheet is aged after being stored and cooled.

[0044] In step nine above, the aged sheet is slit to obtain the finished product.

[0045] Example 2

[0046] An environmentally friendly composite biaxially oriented film, the formulation of which includes polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, copolymer antiblocking agent, and homopolymer high-slip antiblocking agent; polypropylene, antistatic agent, and slip agent are core layer materials; maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, and copolymer antiblocking agent are first core layer materials; polypropylene and homopolymer high-slip antiblocking agent are second core layer materials. The specific mass percentages of each component are as follows: The main unit contains 96% polypropylene, 1.5% antistatic agent, and 2.5% slip agent; Auxiliary unit one contains 1% maleic anhydride-grafted PP, 7% maleic anhydride-grafted EVA, 12% ethylene-octene copolymer, 50% ethylene-butene copolymer, 28% C5 petroleum resin, and 2% copolymer anti-blocking agent; Auxiliary unit two contains 90% polypropylene and 10% homopolymer high-slip anti-blocking agent. The agents are: polypropylene H3035, antistatic agent AS2235PP, slip agent S7220, maleic anhydride-grafted PP 18722, ethylene-octene copolymer FT810, maleic anhydride-grafted EVA 38E802, ethylene-butene copolymer FT411, C5 petroleum resin PZX-H2100, copolymer antiblocking agent AB05CPP, and homopolymer high slip antiblocking agent SAB16; the preparation method is the same as in Example 1.

[0047] Example 3

[0048] An environmentally friendly composite biaxially oriented film, the formulation of which includes polypropylene, antistatic agent, slip agent, maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, copolymer antiblocking agent, and homopolymer high-slip antiblocking agent; polypropylene, antistatic agent, and slip agent are core layer materials; maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, and copolymer antiblocking agent are first core layer materials; polypropylene and homopolymer high-slip antiblocking agent are second core layer materials. The specific mass percentages of each component are as follows: The main unit contains 99% polypropylene, 0.5% antistatic agent, and 0.5% slip agent; Auxiliary unit one contains 3% maleic anhydride-grafted PP, 5% maleic anhydride-grafted EVA, 20% ethylene-octene copolymer, 45% ethylene-butene copolymer, 17% C5 petroleum resin, and 10% copolymer anti-blocking agent; Auxiliary unit two contains 99% polypropylene and 1% homopolymer high-slip anti-blocking agent. The agents are: polypropylene H3035, antistatic agent AS2235PP, slip agent S7220, maleic anhydride-grafted PP 18722, ethylene-octene copolymer FT810, maleic anhydride-grafted EVA 38E802, ethylene-butene copolymer FT411, C5 petroleum resin PZX-H2100, copolymer antiblocking agent AB05CPP, and homopolymer high slip antiblocking agent SAB16; the preparation method is the same as in Example 1.

[0049] The specific component ratios for each embodiment are shown in the table below:

[0050]

[0051]

[0052] Comparative Example 1

[0053] The composite biaxially oriented film is produced using a traditional method, with 98.1% polypropylene, 1.1% antistatic agent, and 0.7% slip agent as the core layer. A layer of polyethyleneimine aqueous solution is coated on top of the core layer, dried, and then a layer of EVA hot melt adhesive is extruded and coated onto the film before laminating it. The same operation is performed below the core layer, where the mass percentage of polyethyleneimine aqueous solution and EVA hot melt adhesive is 100%.

[0054] Comparative Example 2

[0055] The traditional method for producing composite biaxially oriented films involves using 96% polypropylene, 1.5% antistatic agent, and 2.5% slip agent as the core layer. A layer of polyethyleneimine aqueous solution is coated on top of the core layer, dried, and then an EVA hot melt adhesive is extruded and coated onto the film before laminating it. The same operation is performed below the core layer. The mass percentage of polyethyleneimine aqueous solution and EVA hot melt adhesive is 100%.

[0056] Comparative Example 3

[0057] The traditional method is used to produce a composite biaxially oriented film. The core layer consists of 99% polypropylene, 0.5% electrostatic agent, and 0.5% slip agent. A layer of polyethyleneimine aqueous solution is coated on top of the core layer and dried. Then, a layer of EVA hot melt adhesive is extruded and coated onto the film and laminated with it. The same operation is performed below the core layer. The mass percentage of polyethyleneimine aqueous solution and EVA hot melt adhesive is 100%.

[0058] The above Examples 1-3 and Comparative Examples 1-3 were tested to obtain the following data:

[0059]

[0060] By comparing the data from the above items, it can be concluded that: the haze of the product prepared using the process of this invention is significantly greater than that of conventional products, indicating that the composite functional materials in the surface layer 1 are fully utilized, which is beneficial for lamination with paper; the coefficient of friction is significantly higher than that of conventional products, indicating that the prepared product has high viscosity and is easy to laminate with paper; it has obvious heat-sealing properties, while ordinary films do not have heat-sealing properties, allowing the film and paper to be laminated better. Comparing the product density and surface tension performance items between the product of this invention and ordinary films, it was found that there is no significant difference in performance. Therefore, it can be concluded that the product of this invention, produced using the preparation process of this invention, not only omits various intermediate coating processes and reduces intermediate production steps, i.e., the film lamination effect can be formed by controlling specific temperatures, wind speeds, rotation speeds, etc.; but also makes most of the properties of the produced product indistinguishable from those of ordinary films.

[0061] Based on the above scheme, the advantages of the present invention are as follows: The present invention improves the functionality of the surface layer of the BOPP film base film by replacing surface layer 1 with six materials: maleic anhydride-grafted PP, maleic anhydride-grafted EVA, ethylene-octene copolymer, ethylene-butene copolymer, C5 petroleum resin, and copolymer anti-blocking agent. Surface layer 2 is replaced with polypropylene and homopolymer high-slip anti-blocking agent. As long as the substrate is directly laminated with paper and other materials under appropriate temperature and pressure, various intermediate coating processes are omitted, reducing intermediate production steps. In production, this achieves cost reduction and efficiency improvement. At the same time, it reduces the environmental pollution caused by the processing of biaxially oriented film products in the prior art, and also reduces energy consumption, product costs, and environmental protection expenses. Simultaneously, a three-layer co-extrusion production line is provided for production. This involves selecting and batching raw materials; melting and extruding them separately through an extruder, collecting them at the die head; extruding them through the die head to the casting system for casting; undergoing longitudinal stretching of more than 5 times; undergoing transverse stretching of 9.2-9.7 times; edge trimming and automatic thickness measurement via a traction system; and finally, winding to form our semi-finished product. After aging in a specific temperature environment, it is then slit by a slitting machine to meet customer specifications. Following product inspection, it is packaged, weighed, and stored, completing the entire product manufacturing process. This reduces environmental pollution while improving product characteristics.

[0062] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from its spirit or essential characteristics. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, all variations falling within the meaning and scope of equivalents of the claims are intended to be included within the present invention. No reference numerals in the claims should be construed as limiting the scope of the claims.

Claims

1. An environmentally friendly composite biaxially oriented film, characterized by: The formula includes polypropylene, antistatic agent, slip agent, maleic anhydride grafted PP, ethylene-octene copolymer, maleic anhydride grafted EVA, ethylene-butene copolymer, carbon five petroleum resin, copolymer anti-blocking agent, homopolymer high slip anti-blocking agent; The polypropylene, the antistatic agent and the slip agent are core layer materials, and the mass percentage of each component is: 96-99% of polypropylene, 0.5-1.5% of antistatic agent, and 0.5-2.5% of slip agent; The maleic anhydride grafted PP, the maleic anhydride grafted EVA, the ethylene-butene copolymer, the ethylene-octene copolymer, the carbon five petroleum resin and the copolymer anti-blocking agent are first surface layer materials, and the mass percentage of each component is: 1-5% of maleic anhydride grafted PP, 5-10% of maleic anhydride grafted EVA, 10-20% of ethylene-butene copolymer, 30-50% of ethylene-octene copolymer, 10-30% of carbon five petroleum resin and 1-10% of copolymer anti-blocking agent; The polypropylene and the homopolymer high slip anti-blocking agent are second surface layer materials, and the mass percentage of each component is: 90-99% of polypropylene and 1-10% of homopolymer high slip anti-blocking agent; The preparation method of the above-mentioned environment-friendly composite biaxial stretching film includes the following steps: step one, raw material proportioning; step two, melt extrusion; step three, extrusion casting; step four, longitudinal stretching; step five, transverse stretching; step six, traction edge cutting; step seven, winding and storage; step eight, aging treatment; and step nine, cutting finished product. In the above-mentioned step one, raw materials are prepared according to the formula proportion, and the raw materials are pretreated; In the above-mentioned step two, the raw materials are melted and added to an extruder for extrusion; In the above-mentioned step three, the extruded raw materials in a molten state are extruded from a die, and a sheet is formed through shaping, cooling and crystallization; In the above-mentioned step four, the sheet is stretched longitudinally; In the above-mentioned step five, the sheet is stretched transversely; In the above-mentioned step six, the stretched sheet is subjected to traction, cooling, edge trimming, thickness measurement and corona processing; In the above-mentioned step seven, the sheet after corona treatment is wound and stored; In the above-mentioned step eight, the sheet after storage and cooling is subjected to aging treatment; In the above-mentioned step nine, the sheet after aging treatment is cut to obtain the finished product. In the above-mentioned step one, dry and pure raw materials are selected, mixed uniformly, and then polypropylene, antistatic agent, slip agent, maleic anhydride grafted PP, ethylene-octene copolymer, maleic anhydride grafted EVA, ethylene-butene copolymer, carbon five petroleum resin, copolymer anti-blocking agent and homopolymer high slip anti-blocking agent are added to a main machine, auxiliary machine one and auxiliary machine two; the polypropylene, the antistatic agent and the slip agent are added to the main machine; the maleic anhydride grafted PP, the maleic anhydride grafted EVA, the ethylene-butene copolymer, the ethylene-octene copolymer, the carbon five petroleum resin and the copolymer anti-blocking agent are added to the auxiliary machine one; and the polypropylene and the homopolymer high slip anti-blocking agent are added to the auxiliary machine two. In the second step, the temperature of the main machine is set to 240-250 DEG C, the temperature of the auxiliary machine one and the auxiliary machine two is set to 210-245 DEG C, the rotating speed of the main machine is set to 70-90 rpm, the rotating speed of the auxiliary machine one is set to 100-110 rpm, the thickness of the surface layer is set to 3 microns, the rotating speed of the auxiliary machine two is set to 40-60 rpm, and the thickness of the surface layer is set to 1 micron.

2. The environment-friendly composite biaxial-stretching film according to claim 1, characterized in that: The mass percentage of the maleic anhydride grafted PP in the first surface layer material is 5%, the mass percentage of the maleic anhydride grafted EVA is 10%, the mass percentage of the ethylene-butene copolymer is 20%, the mass percentage of the ethylene-octene copolymer is 36%, the mass percentage of the carbon five petroleum resin is 24%, and the mass percentage of the copolymer anti-blocking agent is 5%.

3. The environment-friendly composite biaxial oriented film according to claim 2, characterized in that: In the third step, the extruder extrudes the raw material in a molten state, and after filtration, the three layers of molten material are transported to the casting machine through the die head, and extruded by the auxiliary traction device, wherein the temperature of the chill roller in the casting machine is set to 36 DEG C, and the temperature of the water tank is set to 35 DEG C.

4. The environment-friendly composite biaxial oriented film according to claim 3, characterized in that: In the fourth step, longitudinal stretching is carried out by the longitudinal stretching machine, the temperature of the preheating zone of the longitudinal stretching machine is set to 100-130 DEG C, the temperature of the stretching zone is set to 85-111 DEG C, and the temperature of the setting zone is set to 110-140 DEG C.

5. The environment-friendly composite biaxial oriented film according to claim 4, characterized in that: In the fifth step, transverse stretching is carried out by the transverse stretching machine, the temperature of the preheating zone of the transverse stretching machine is set to 160-170 DEG C, the circulating air speed of the preheating zone is 60%-90%, the temperature of the stretching zone is set to 150-160 DEG C, the circulating air speed of the stretching zone is 80%-90%, the temperature of the setting zone is set to 150-170 DEG C, the circulating air speed of the setting zone is 80%-90%, the air speed of the upper cooling zone of the transverse stretching machine is set to 60%-95%, and the air speed of the lower cooling zone is set to 50%-90%.

6. The environment-friendly composite biaxial oriented film according to claim 5, characterized in that: In the sixth step, the stretched sheet is pulled, the excess part and the burr edge part are cut off, and thickness measurement and single-sided corona treatment are carried out, and the output power of the upper corona treatment is 98 kW; In the seventh step, the sheet after cutting the edge is wound and stored, the winding tension is set to 23%, the winding pressure is set to 32%, the rolling tension is set to 135%, the broken film winding tension is set to 14%, and the winding mode adopts the contact winding mode.

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