A kind of adhesive film and its preparation method and application

Abstract

The application discloses a kind of adhesive film and its preparation method and application, belong to adhesive film technical field.The adhesive film of the application is by adding PP grafting maleic anhydride and alpha-olefin and copolymer of ethylene, while controlling the carbon atom number of alpha-olefin in alpha-olefin and copolymer of ethylene is above 4 and each component dosage is in suitable range, so that it has excellent bonding performance, is suitable for the bonding of metal and continuous fiber reinforced thermoplastic composite material, and when being used for the bonding of metal and continuous fiber reinforced thermoplastic composite material, not only excellent bonding performance can be obtained, but also excellent impact resistance of bonded parts can be endowed.

Description

Technical Field

[0001] This application relates to the field of adhesive film technology, specifically to an adhesive film, its preparation method, and its application. Background Technology

[0002] Against the backdrop of increasingly scarce global natural and oil resources, new energy vehicles, led by electric vehicles, have begun to emerge as a powerful force. Compared to traditional gasoline vehicles, they use electricity and do not produce harmful gases such as carbon monoxide and carbon dioxide, thus reducing environmental pollution. Protective plates, installed on the underside of the vehicle, are load-bearing components for the power battery pack in new energy vehicles, protecting it from damage by external impacts and pressure. Currently, automotive protective plates mainly use metal alloy materials, but these are heavy, significantly reducing battery range; moreover, the chassis is frequently in contact with rainwater and oil, causing continuous corrosion of metal parts and posing safety hazards. Continuous fiber reinforced thermoplastic composites, due to their lightweight, high rigidity, high toughness, and recyclability, are widely used in many fields such as automotive, aerospace, military, and electronics. However, pure continuous fiber reinforced thermoplastic composites have poor ductility when facing impacts from stones and sharp objects, failing to adequately protect the battery. Therefore, combining continuous fiber reinforced thermoplastic composites with metal materials, leveraging their respective advantages, and applying them to the protective plates of power battery vehicles represents an innovation in the industry.

[0003] Patent CN 217788632 U discloses a battery protective base plate, including an upper fiber-reinforced resin layer, a metal plate, and a lower fiber-reinforced resin layer. Both the upper and lower fiber-reinforced resin layers are made of continuous fiber-reinforced thermoplastic resin. The paper compares the pulverization zone and hollowness of the protective base plate under the impact of a falling ball with different fiber-reinforced resin layer thickness ratios to illustrate the bonding strength between different thickness ratios and the metal plate. However, it does not show the influence of the adhesive layer medium on the bonding performance and impact resistance of the composite material and the metal plate, nor does it synergistically correlate the bonding strength between the fiber-reinforced resin layer and the metal plate with the impact energy absorption. Summary of the Invention

[0004] Based on the deficiencies of the existing technology, the purpose of this application is to provide an adhesive film, its preparation method and application. The adhesive film is suitable for bonding metals and continuous fiber reinforced thermoplastic composites, and can impart excellent bonding performance and impact resistance to bonded parts (such as protective plates).

[0005] To achieve the above objectives, in a first aspect, this application provides an adhesive film comprising the following components in parts by weight: 100 parts of PP (polypropylene) resin PP grafted with maleic anhydride, 60-145 parts. 80-190 parts of thermoplastic elastomer; The thermoplastic elastomer is a copolymer of α-olefin and ethylene, wherein the α-olefin has 4 or more carbon atoms.

[0006] During their research, the inventors discovered that introducing PP grafted with maleic anhydride into polypropylene resin can improve the adhesion between the adhesive film and the metal. The selection of the aforementioned specific thermoplastic elastomer can improve adhesion because it possesses a unique microscopic two-phase structure and is softer. During casting or blow molding, it can optimize the rheological properties of the adhesive film, ensuring good spreading of the molten adhesive film and allowing it to penetrate into the microscopic pores of the metal surface in the next lamination process, enhancing interfacial adhesion. Furthermore, its microscopic phase separation structure allows it to disperse in the adhesive film matrix... When the adhesive is in the body, it forms an "island" structure. When external forces (especially impact forces and peeling forces) are applied to the bonding interface, the stress will concentrate inside the adhesive layer. The micro-regions of thermoplastic elastomers, as stress concentration points, can induce a large number of crazes and shear bands in the surrounding matrix. The process of generating crazes and shear bands requires a lot of energy. More importantly, these numerous and fine crazes and shear bands can effectively terminate the propagation of cracks and prevent them from penetrating into large cracks that lead to overall failure. This greatly improves the fracture toughness and impact resistance of the interface.

[0007] The adhesive film, under the combined action of appropriate amounts of each component, has excellent adhesive properties and is suitable for bonding metals to continuous fiber reinforced thermoplastic composites. Moreover, when used for bonding metals to continuous fiber reinforced thermoplastic composites, it not only achieves excellent adhesive properties but also imparts excellent impact resistance to the bonded parts (such as protective plates).

[0008] Preferably, the sum of the mass percentages of the PP resin, PP-grafted maleic anhydride, and thermoplastic elastomer in the film is 95% or more, such as 95%, 95.5%, 96%, 96.5%, 97%, 97.5%, 98%, 98.5%, 99%, 99.5%, 100%, or any two of these ranges. The PP-grafted maleic anhydride is 60-145 parts by weight, such as 60 parts by weight, 70 parts by weight, 80 parts by weight, 90 parts by weight, 100 parts by weight, 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 145 parts by weight, or any two of these ranges.

[0009] The thermoplastic elastomer is 80 to 190 parts by weight, such as 80 parts by weight, 90 parts by weight, 100 parts by weight, 110 parts by weight, 120 parts by weight, 130 parts by weight, 140 parts by weight, 150 parts by weight, 160 parts by weight, 170 parts by weight, 180 parts by weight, 190 parts by weight, or any two of the above ranges.

[0010] The PP grafted with maleic anhydride and the thermoplastic elastomer together comprise 140 to 335 parts by weight, such as 140 parts by weight, 160 parts by weight, 180 parts by weight, 200 parts by weight, 220 parts by weight, 240 parts by weight, 260 parts by weight, 280 parts by weight, 300 parts by weight, 320 parts by weight, 335 parts by weight, or any range formed by any two of the above.

[0011] The weight ratio of the PP grafted maleic anhydride to the thermoplastic elastomer is (0.3~1.8):1, such as 0.3:1, 0.4:1, 0.6:1, 0.8:1, 1:1, 1.2:1, 1.3:1, 1.4:1, 1.5:1, 1.6:1, 1.7:1, 1.8:1, or any two of the above ranges. Preferably, the weight ratio of the PP grafted maleic anhydride to the thermoplastic elastomer is (0.5~1):1, to further improve the adhesion between the adhesive film and the metal, and to enhance the impact resistance of the bonded component. In the thermoplastic elastomer, the α-olefin has 4 or more carbon atoms, such as 4, 5, 6, 7, 8, 9, 10, or any two of the above ranges.

[0012] Preferably, the α-olefin in the thermoplastic elastomer has 4 to 8 carbon atoms to make it softer and better wet the steel plate, further improving the adhesion between the film and the metal. For example, the thermoplastic elastomer includes at least one of ethylene-butene copolymer, ethylene-hexene copolymer, and ethylene-octene copolymer. More preferably, the thermoplastic elastomer includes ethylene-octene copolymer to make the adhesion between the film and the metal even stronger.

[0013] Preferably, the ethylene content in the thermoplastic elastomer is 60wt% to 90wt%. For example, the ethylene content in the thermoplastic elastomer is within the range formed by any two of the following: 60%, 65%, 79%, 75%, 80%, 85%, 90%, or more.

[0014] The ethylene content in the thermoplastic elastomer was determined by the following method: The test was performed in accordance with ASTM D5576 - Standard Practice for Determination of Structural Features in Polyolefins and Polyolefin Copolymers by Infrared Spectrophotometry (FT-IR).

[0015] Preferably, the melting point of the PP and the PP grafted with maleic anhydride is independently ≤170℃, such as being independently within the range of 130℃, 140℃, 145℃, 150℃, 155℃, 160℃, 170℃, or any two of the above. More preferably, the melting point of the PP and the PP grafted with maleic anhydride is independently 120~150℃.

[0016] When the melting points of the PP and the PP-grafted maleic anhydride are each independently ≤170℃, and especially when they are each independently 120~150℃, the adhesion between the adhesive film and the metal is stronger.

[0017] The melting point of the PP and the melting point of the PP grafted with maleic anhydride were obtained by differential scanning calorimetry (DSC).

[0018] Preferably, the grafting rate of maleic anhydride in the PP grafted with maleic anhydride is 0.3 wt% to 1.5 wt%. For example, the grafting rate of maleic anhydride in the PP grafted with maleic anhydride is within the range formed by any two of the following: 0.3 wt%, 0.5 wt%, 0.6 wt%, 0.7 wt%, 0.8 wt%, 0.9 wt%, 1.0 wt%, 1.1 wt%, 1.2 wt%, 1.3 wt%, 1.4 wt%, 1.5 wt%.

[0019] The grafting rate of maleic anhydride in the PP grafted maleic anhydride was determined by acid-base titration, as follows: First, a certain amount of PP grafted maleic anhydride was weighed and placed in an Erlenmeyer flask, and an excess of alkaline standard solution was added. The mixture was heated to completely neutralize the anhydride on the graft. Then, the excess alkali was titrated with an acid standard solution, and the content of anhydride was calculated, thereby obtaining the grafting rate.

[0020] Preferably, the PP resin and the PP grafted with maleic anhydride in the PP are each independently at least one of homopolymer PP and copolymer PP, wherein the mass percentage of ethylene monomer in the copolymer PP is independently 2% to 15%. The mass percentage of ethylene monomer in the copolymer PP is determined with reference to the standard ASTM D5576 - Standard Practice for Determination of Structural Features in Polyolefins and Polyolefin Copolymers by Infrared Spectrophotometry (FT-IR).

[0021] When the PP resin and / or the PP grafted with maleic anhydride in the PP includes copolymer PP, each copolymer PP independently includes at least one of random copolymer PP, block copolymer PP, and ternary copolymer PP.

[0022] Preferably, the method for preparing PP grafted with maleic anhydride includes the following steps: PP, maleic anhydride and initiator are mixed, dispersed, melted, extruded and granulated to obtain PP grafted with maleic anhydride.

[0023] Preferably, when preparing the PP grafted with maleic anhydride, the mass ratio of PP, maleic anhydride and initiator is 100:(2.5~0.3):(2~0.6).

[0024] Preferably, when preparing the PP grafted with maleic anhydride, the PP used has a melting point ≤170℃, such as a range of 130℃, 140℃, 145℃, 150℃, 155℃, 160℃, 170℃, or any two of the above. In some embodiments, when preparing the PP grafted with maleic anhydride, the PP used has a melting point of 120~150℃.

[0025] Preferably, when preparing the PP grafted with maleic anhydride, the PP used is at least one of homopolymer PP and copolymer PP.

[0026] Preferably, the initiator used in preparing the PP grafted with maleic anhydride is a peroxide.

[0027] Preferably, the peroxide includes at least one of cumene peroxide and di-tert-butyl peroxide.

[0028] Preferably, in preparing the PP grafted with maleic anhydride, melting, extrusion, and granulation are carried out in a twin-screw extruder. The twin-screw extruder has a twin-screw temperature range of 190~230℃, a screw speed of 300~450 rpm, and a screw length-to-diameter ratio of 32~48.

[0029] The PP grafted with maleic anhydride can also be obtained commercially.

[0030] Preferably, the thickness of the adhesive film is 0.05~0.3 mm. For example, the thickness of the adhesive film is within the range of any two of the following: 0.05 mm, 0.1 mm, 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm.

[0031] Depending on actual needs, at least one of antioxidants and weather-resistant agents can also be added to the adhesive film.

[0032] For example, the antioxidant includes at least one of hindered phenolic antioxidants, thioester antioxidants, phosphite antioxidants, and hindered amine antioxidants. The antioxidant may be selected in the range of 0 to 0.8 parts by weight, such as 0.05 parts by weight, 0.2 parts by weight, 0.4 parts by weight, 0.6 parts by weight, 0.8 parts by weight, or any range formed by two or more of the above.

[0033] Secondly, this application provides a method for preparing the adhesive film, including the following steps: mixing and dispersing the component raw materials, melting, extruding, granulating, casting or blow molding into a film to obtain the adhesive film.

[0034] Preferably, in preparing the adhesive film, melting, extrusion, and granulation are carried out in a twin-screw extruder. The twin-screw extruder has a twin-screw temperature range of 190~230°C, a screw speed of 300~450 rpm, and a screw length-to-diameter ratio of 32~48.

[0035] Preferably, the drooling or blow molding temperature is 190~210℃.

[0036] Thirdly, this application provides a protective plate comprising the aforementioned adhesive film.

[0037] Preferably, the protective plate comprises, from bottom to top, a first continuous fiber reinforced thermoplastic composite material layer, a first adhesive film layer, a metal plate layer, a second adhesive film layer, and a second continuous fiber reinforced thermoplastic composite material layer, wherein the materials of the first adhesive film layer and the second adhesive film layer each independently include the adhesive film.

[0038] Preferably, the first continuous fiber reinforced thermoplastic composite material layer comprises four or more unidirectional continuous fiber reinforced thermoplastic composite material sheets. For example, the number of unidirectional continuous fiber reinforced thermoplastic composite material sheets in the first continuous fiber reinforced thermoplastic composite material layer is within any range formed by four, five, six, seven, eight, nine, ten or more layers.

[0039] Preferably, the second continuous fiber reinforced thermoplastic composite layer comprises two or more unidirectional continuous fiber reinforced thermoplastic composite sheet layers. For example, in the first continuous fiber reinforced thermoplastic composite layer, the number of unidirectional continuous fiber reinforced thermoplastic composite sheet layers is within any range of 4, 5, 6, 7, 8, 9, 10 or more layers.

[0040] Preferably, in the first continuous fiber reinforced thermoplastic composite layer and the second continuous fiber reinforced thermoplastic composite layer, the layup angle difference of the continuous fibers in two adjacent unidirectional continuous fiber reinforced thermoplastic composite sheet layers is within the range of 0° to 90°, such as the range formed by any two of 0°, 5°, 10°, 15°, 20°, 25°, 30°, 35°, 40°, 45°, 50°, 55°, 60°, 65°, 70°, 75°, 80°, 85°, 90° or above.

[0041] Preferably, the content of continuous fibers in each unidirectional continuous fiber reinforced thermoplastic composite sheet is independently 40wt%~75wt%, such as the range formed by any two of 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, or more.

[0042] Preferably, the continuous fibers in each unidirectional continuous fiber reinforced thermoplastic composite sheet are each independently at least one of glass fiber, carbon fiber, aramid fiber, and basalt fiber.

[0043] Preferably, the thermoplastic resin in each unidirectional continuous fiber reinforced thermoplastic composite sheet includes at least one of PP, PE, PA6, PA66, etc.

[0044] Preferably, the content of continuous fibers in each unidirectional continuous fiber reinforced thermoplastic composite sheet is independently 40wt%~75wt%, such as the range formed by any two of 40wt%, 45wt%, 50wt%, 55wt%, 60wt%, 65wt%, 70wt%, 75wt%, or more.

[0045] Preferably, each unidirectional continuous fiber reinforced thermoplastic composite sheet independently includes flame retardant masterbatch and at least one of antioxidant, weathering agent, and lubricant.

[0046] Preferably, the proportion of flame retardant masterbatch in the unidirectional continuous fiber reinforced thermoplastic composite sheet is 10wt%~30wt%, such as the range formed by any two of 10wt%, 15wt%, 20wt%, 25wt%, 30wt%, or more.

[0047] Preferably, the antioxidant accounts for 0.1 wt% to 1 wt% of the unidirectional continuous fiber reinforced thermoplastic composite sheet, such as the range formed by any two of 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, or more.

[0048] Preferably, the weathering agent accounts for 0.1 wt% to 1 wt% of the unidirectional continuous fiber reinforced thermoplastic composite sheet, such as the range formed by any two of 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, or more.

[0049] Preferably, the lubricant accounts for 0.1 wt% to 1 wt% of the unidirectional continuous fiber reinforced thermoplastic composite sheet, such as the range formed by any two of 0.1 wt%, 0.2 wt%, 0.4 wt%, 0.6 wt%, 0.8 wt%, 1 wt%, or more.

[0050] Preferably, the first continuous fiber reinforced thermoplastic composite layer and the second continuous fiber reinforced thermoplastic composite layer each independently comprise continuous fiber reinforced PP composite material.

[0051] Preferably, the thickness of the first continuous fiber reinforced thermoplastic composite layer is 0.3 mm to 1.5 mm, such as the range formed by any two of the following: 0.3 mm, 0.4 mm, 0.5 mm, 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm.

[0052] Preferably, the thickness of the second continuous fiber reinforced thermoplastic composite layer is 0.6 mm to 2.2 mm, such as the range formed by any two of the following: 0.6 mm, 0.7 mm, 0.8 mm, 0.9 mm, 1.0 mm, 1.1 mm, 1.2 mm, 1.3 mm, 1.4 mm, 1.5 mm, 1.6 mm, 1.7 mm, 1.8 mm, 1.9 mm, 2.0 mm, 2.1 mm, 2.2 mm.

[0053] Preferably, the thickness of the metal plate layer is 0.5 mm to 3.0 mm, such as the range formed by any two of the following: 0.5 mm, 0.7 mm, 1.0 mm, 1.2 mm, 1.5 mm, 1.8 mm, 2.0 mm, 2.2 mm, 2.5 mm, 2.8 mm, 3.0 mm, or more.

[0054] Preferably, the metal plate layer includes at least one of steel plate and aluminum plate. The steel plate includes at least one of perforated steel plate, steel mesh, etc.; the aluminum plate includes at least one of perforated aluminum plate, aluminum mesh, etc.

[0055] Preferably, the protective plate includes the following steps: laying up a first continuous fiber reinforced thermoplastic composite material, a first adhesive film, a metal plate, a second adhesive film, and a second continuous fiber reinforced thermoplastic composite material in sequence, and hot-pressing them to obtain the protective plate, wherein the hot-pressing temperature is 200~245℃, the hot-pressing pressure is 2.5~4 bar, and the hot-pressing speed is 2~3.5 m / min.

[0056] Fourthly, this application provides the application of the aforementioned protective plate in automobiles.

[0057] Fifthly, this application provides the application of the adhesive film in the bonding of metal and continuous fiber reinforced thermoplastic composite materials.

[0058] Preferably, the continuous fiber reinforced thermoplastic composite material includes a continuous fiber reinforced PP composite material.

[0059] Compared with the prior art, the beneficial effects of this application are as follows: the adhesive film of this application, by adding PP grafted maleic anhydride and α-olefin-ethylene copolymer, while controlling the number of carbon atoms of α-olefin in α-olefin-ethylene copolymer to be more than 4 and the amount of each component to be within a suitable range, gives it excellent adhesive properties. It is suitable for bonding metals and continuous fiber reinforced thermoplastic composites. Moreover, when used for bonding metals and continuous fiber reinforced thermoplastic composites, it can not only obtain excellent adhesive properties, but also give the bonded parts (such as protective plates) excellent impact resistance. Detailed Implementation

[0060] To better illustrate the purpose, technical solutions, and advantages of this application, the following description, in conjunction with specific embodiments and comparative examples, aims to provide a detailed understanding of the content of this application, rather than limiting it. All other embodiments obtained by those skilled in the art without inventive effort are within the protection scope of this application. Unless otherwise specified, the experimental reagents and instruments involved in the implementation of this application are commonly used reagents and instruments. In this application, the technical features described in an open-ended manner include both closed-ended technical solutions composed of the listed features and open-ended technical solutions that include the listed features.

[0061] The raw materials used in the following embodiments and comparative examples are shown below. Unless otherwise specified, all raw materials are commercially available. In addition, the same raw materials were used in each parallel experiment: PP resin 1: Copolymer polypropylene, PP F4908, purchased from Sinopec Maoming Petrochemical, melting point 135℃; PP resin 2: Copolymer polypropylene, PPUT8012M, purchased from Sinopec Maoming Petrochemical, melting point 145℃; PP resin 3: Copolymer polypropylene, PP J-750, purchased from Lotte Chemical, melting point 150℃; PP resin 4: Homopolymer polypropylene, N-Z30S, purchased from Sinopec Maoming Petrochemical, melting point 165℃; PP resin 5: Copolymer polypropylene, K8003, purchased from Sinopec Maoming Petrochemical, melting point 165℃; PP grafted with maleic anhydride 1: maleic anhydride grafting rate 1.0wt%, melting point 136℃, preparation method is as follows: PP, maleic anhydride and cumene peroxide are mixed and dispersed in a mass ratio of 100:4:0.3, and added to a twin-screw extruder for melting, extrusion and granulation. The twin-screw temperature is 210℃, the screw speed is 330 rpm, and the screw length-to-diameter ratio is 48. The PP used is PP resin 1. PP grafted with maleic anhydride 2: maleic anhydride grafting rate of 0.5wt%, melting point of 135℃. The preparation method is different from that of PP grafted with maleic anhydride 1 in that the PP used is PP resin 2, and the mass ratio of PP, maleic anhydride and cumene peroxide is 100:3:0.2. PP grafted with maleic anhydride 3: maleic anhydride grafting rate of 1.5wt%, melting point of 149℃. The preparation method is different from that of PP grafted with maleic anhydride 1 in that the PP used is PP resin 3, and the mass ratio of PP, maleic anhydride and cumene peroxide is 100:4.5:0.4. PP grafted maleic anhydride 4: maleic anhydride grafting rate 0.9wt%, melting point 163℃. The preparation method is different from that of PP grafted maleic anhydride 1 in that the PP used is PP resin 4. PP grafted maleic anhydride 5: maleic anhydride grafting rate 1.0wt%, melting point 166℃. The preparation method is different from that of PP grafted maleic anhydride 1 in that the PP used is PP resin 5. Thermoplastic elastomer 1: ENGAGE 8150, purchased from Dow Chemical, USA, ethylene-octene copolymer; Thermoplastic elastomer 2: ENGAGE 8137, purchased from Dow Chemical, USA, ethylene-octene copolymer; Thermoplastic elastomer 3: 1018EA, purchased from ExxonMobil, ethylene-hexene copolymer; Thermoplastic elastomer 4: DF610, purchased from Mitsui Chemicals, ethylene-butene copolymer; Thermoplastic elastomer 5:6102, purchased from ExxonMobil, ethylene-propylene copolymer; Thermoplastic elastomer 6: Grade Elvax resin 250, purchased from DuPont, USA, ethylene-ethyl acetate copolymer (EVA); Antioxidant: A mixture of antioxidant 1010 and antioxidant 168 in a 1:1 mass ratio, commercially available.

[0062] Each of the following embodiments and comparative examples provides a film, the specific composition of which is shown in Table 1 or Table 2. Their preparation methods include the following steps: The raw materials are mixed and dispersed, then added to a twin-screw extruder for melting, extrusion, and granulation, and finally cast into a film to obtain the adhesive film. The twin-screw extruder has a twin-screw temperature of 210℃, a screw speed of 330 rpm, a screw length-to-diameter ratio of 40, and a casting temperature of 200℃.

[0063] The film thickness obtained using the film formulations of each embodiment and comparative example is 0.1 mm.

[0064] Table 1 Table 2 The above-described examples and comparative examples of adhesive films are used to prepare protective panels. The preparation method includes the following steps: The layers are laid up in the following order: continuous fiber reinforced thermoplastic composite, film, metal plate, film, and continuous fiber reinforced thermoplastic composite. The layers are then hot-pressed, and a roller peeling strip with a length of 350 mm and a width of 60 mm is prepared in accordance with GB / T 1457-2005 standard. The continuous fiber reinforced thermoplastic composites are all 1.0 mm thick and consist of 4 layers of unidirectional continuous fiber reinforced thermoplastic composite sheets with the following layup design: 0° / 90° / 90° / 0°. The thickness of each unidirectional continuous fiber reinforced thermoplastic composite sheet is 0.25 mm. Each unidirectional continuous fiber reinforced thermoplastic composite sheet contains the following components by mass percentage: 65 wt% glass fiber, 29.6 wt% PP, 5 wt% compatibilizer (i.e., PP grafted with maleic anhydride 1), and 0.4 wt% antioxidant (a mixture of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1). The PP is grade EP640V and was purchased from Sinopec Maoming Petrochemical. The metal sheet is a galvanized steel sheet, model HC420 / 780DP, with a thickness of 0.8mm; The hot pressing temperature is 240℃, the hot pressing pressure is 3 bar, and the hot pressing speed is 3 m / min.

[0065] The following performance tests were performed on the obtained protective plate: Peel strength: Tested according to GB / T 1457-2005 Test method for peel strength of sandwich structure rollers; Impact resistance: Tested according to ASTM D7136 / D7136M-20, with an impact energy of 300J, a ball head diameter of 25mm, and the maximum dent depth of the protective plate was measured.

[0066] The test results are shown in Table 3.

[0067] Table 3 As can be seen from the above data, when the adhesive films of the various embodiments of this application are used for bonding metal and continuous fiber reinforced thermoplastic composite materials, they can impart excellent bonding performance and impact resistance. For example, the resulting protective plate has a roller peel strength of more than 240 N·mm / mm; and in the impact resistance test, the maximum indentation depth is less than 9 mm.

[0068] As can be seen from the comparison of Examples 1, 4-7, when the melting point of each PP in the adhesive film is independently within the range of 120-150℃, the adhesive film can better melt and penetrate into the microscopic uneven pores of the metal surface, resulting in a better bonding effect.

[0069] Comparison of Examples 1 and 10-11 shows that when the melting point of maleic anhydride grafted onto PP in the adhesive film is in the range of 120-150℃, the adhesive film can better melt and penetrate into the microscopic uneven pores of the metal surface, resulting in a better bonding effect.

[0070] As can be seen from the comparison of Examples 1, 12-14 and Comparative Examples 1-2, when the added thermoplastic elastomer is EVA, the adhesion to the steel plate is poor because EVA has poor compatibility with PP and the uniformity of the adhesive film is poor. However, when the added thermoplastic elastomer is a copolymer of α-olefin and ethylene, and the number of carbon atoms in the α-olefin is more than 4, the thermoplastic elastomer is softer and can better wet the steel plate, further improving the adhesion performance.

[0071] In Comparative Example 3, the excessive addition of PP-grafted maleic anhydride and thermoplastic elastomer resulted in poor adhesion.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of this application and are not intended to limit the scope of protection of this application. Although this application has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can be made to the technical solutions of this application without departing from the substance and scope of the technical solutions of this application.

Claims

1. A film, characterized in that, Includes the following components in parts by weight: 100 parts of PP resin PP grafted with maleic anhydride, 60-145 parts. 80-190 parts of thermoplastic elastomer; The thermoplastic elastomer is a copolymer of α-olefin and ethylene, wherein the α-olefin has 4 or more carbon atoms.

2. The adhesive film as described in claim 1, characterized in that, The weight ratio of the PP grafted with maleic anhydride to the thermoplastic elastomer is (0.5~1):

1.

3. The adhesive film as described in claim 1, characterized in that, In the thermoplastic elastomer, the α-olefin has 4 to 8 carbon atoms; preferably, the thermoplastic elastomer includes an ethylene-octene copolymer.

4. The adhesive film as described in claim 1, characterized in that, The melting point of the PP and the PP grafted with maleic anhydride is independently ≤170℃; preferably, the melting point of the PP and the PP grafted with maleic anhydride is independently 120~150℃.

5. The adhesive film as described in claim 1, characterized in that, At least one of the following conditions must be met: (1) The PP resin and the PP grafted with maleic anhydride in the PP are each independently at least one of homopolymer PP and copolymer PP, wherein the mass percentage of ethylene monomer in the copolymer PP is independently 2% to 15%; (2) The ethylene content in the thermoplastic elastomer is 60wt%~90wt%; (3) The grafting rate of maleic anhydride in the PP grafted maleic anhydride is 0.3wt%~1.5wt%.

6. The method for preparing the adhesive film according to any one of claims 1 to 5, characterized in that, Includes the following steps: The raw materials are mixed, dispersed, melted, extruded, granulated, cast, or blown into a film.

7. A protective plate, characterized in that, The film comprising any one of claims 1 to 5.

8. The protective plate as described in claim 7, characterized in that, From bottom to top, it comprises: a first continuous fiber reinforced thermoplastic composite material layer, a first adhesive film layer, a metal plate layer, a second adhesive film layer, and a second continuous fiber reinforced thermoplastic composite material layer, wherein the materials of the first adhesive film layer and the second adhesive film layer each independently comprise the adhesive film according to any one of claims 1 to 5; preferably, the materials of the first continuous fiber reinforced thermoplastic composite material layer and the second continuous fiber reinforced thermoplastic composite material layer comprise continuous fiber reinforced PP composite material.

9. The application of the protective plate as described in claim 7 or 8 in automobiles.

10. The application of the adhesive film as described in any one of claims 1 to 5 in the bonding of metal and continuous fiber reinforced thermoplastic composite material; preferably, the continuous fiber reinforced thermoplastic composite material includes continuous fiber reinforced PP composite material.

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