Polyolefin functional adhesive film, method for preparing the same, and use thereof

Abstract

The application relates to the technical field of functional adhesive films, in particular to a polyolefin functional adhesive film and a preparation method and application thereof. The polyolefin functional adhesive film comprises a surface layer, a middle layer and an inner layer which are sequentially arranged along the thickness direction of the polyolefin functional adhesive film; the surface layer comprises an olefin copolymer, a polyethylene-ester copolymer, a crosslinking sensitizer, a crosslinking assistant, an antioxidant and a light stabilizer; the middle layer comprises an olefin copolymer, a polyethylene-ester copolymer, titanium white, an antioxidant and a light stabilizer; and the inner layer comprises an olefin copolymer, a polyethylene-ester copolymer and a maleic anhydride modified polyethylene-ester copolymer. The polyolefin functional adhesive film has excellent adhesive performance and weather resistance due to the multilayer structure design, and can be used for the corrosion prevention of outdoor metal materials.

Description

Technical Field

[0001] This invention relates to the field of functional adhesive film technology, and in particular to a polyolefin functional adhesive film, its preparation method, and its application. Background Technology

[0002] In the field of modern building materials, metal materials are widely used in various outdoor engineering structures due to their excellent mechanical strength, processing characteristics, and durability. However, metal materials are prone to corrosion in outdoor environments, which affects their service life and operational safety. Currently, outdoor metal corrosion protection mainly employs three protective technologies: paint, powder coating, and polymer film. Among them, traditional paint poses problems such as environmental pollution and harm to the health of construction workers during the application process; powder coating is relatively environmentally friendly, but the coating quality is limited by its thickness, and if it is too thin, it is prone to missed areas, affecting the anti-corrosion effect. In contrast, polymer film coating has gained a larger market share due to its excellent environmental friendliness and uniform coating thickness, and has begun to be widely used in fields such as communication base stations, building curtain walls, roof corrosion protection, and engineering waterproofing.

[0003] Among them, polyolefin film coatings have become the leading product in the current metal corrosion protection market due to their advantages such as good environmental protection, corrosion resistance, and cost performance, occupying the largest market share in the field of polymer film coatings.

[0004] Polyolefin films possess excellent weather resistance and low water vapor permeability, effectively preventing direct contact between corrosive substances and metal substrates. However, to achieve this protective function, a strong and reliable adhesive interface must be formed between the film and the metal. Because polyolefin materials typically have low surface polarity and surface energy, which differs significantly from the surface energy of the metal substrate, it is difficult for them to form a stable bond directly. Therefore, in practical applications, the molecular structure of polyolefins usually needs to be modified and optimized to improve their interfacial bonding performance with the metal.

[0005] Meanwhile, polyolefin films face challenges in outdoor engineering applications, including low surface hardness, poor scratch resistance, and insufficient heat resistance. These issues lead to localized damage during transportation, construction, and service, ultimately affecting their overall weather resistance and corrosion resistance. To address these problems, Chinese patent application CN108485159A introduces cyclic olefin copolymers (COCs) into polyolefins to improve the heat resistance of polyolefin films. However, COCs are costly, making it difficult to meet the economic requirements for large-scale industrial production.

[0006] In view of this, the present invention is hereby proposed. Summary of the Invention

[0007] The purpose of this invention is to provide a polyolefin functional adhesive film, its preparation method and application. The polyolefin functional adhesive film of this invention, through a multi-layer structure, combines excellent adhesive performance, weather resistance and low cost, solving the performance challenges faced by existing polyolefin films in outdoor applications.

[0008] To achieve the above-mentioned objectives of the present invention, a first aspect of the present invention provides a polyolefin functional adhesive film, the polyolefin functional adhesive film comprising a surface layer, a middle layer and an inner layer sequentially stacked along its thickness direction;

[0009] The surface layer comprises, by weight, the following components: 70-80 parts of olefin copolymer, 15-30 parts of polyethylene-ester copolymer, 0.5-2 parts of crosslinking sensitizer, 0.1-0.3 parts of co-crosslinking agent, 0.1-1 parts of antioxidant, and 0.1-0.2 parts of light stabilizer;

[0010] The intermediate layer comprises the following components by weight: 40-50 parts of olefin copolymer, 35-55 parts of polyethylene-ester copolymer, 10-15 parts of titanium dioxide, 0.1-1 parts of antioxidant, and 0.1-0.2 parts of light stabilizer;

[0011] The inner layer comprises the following components by weight: 10-30 parts of olefin copolymer, 40-70 parts of polyethylene-ester copolymer, and 20-40 parts of maleic anhydride-modified polyethylene-ester copolymer.

[0012] In a specific embodiment of the present invention, the olefin copolymer in the surface layer, the olefin copolymer in the intermediate layer, and the olefin copolymer in the inner layer are each independently selected from at least one of polyethylene-propylene copolymer, polyethylene-butene copolymer, polyethylene-octene copolymer, and amorphous α-olefin copolymer.

[0013] In a specific embodiment of the present invention, the polyethylene-ester copolymer in the surface layer, the polyethylene-ester copolymer in the intermediate layer, and the polyethylene-ester copolymer in the inner layer are each independently selected from at least one of polyethylene-vinyl acetate copolymer, polyethylene-methyl acrylate copolymer, polyethylene-ethyl acrylate copolymer, and polyethylene-butyl acrylate copolymer.

[0014] In a specific embodiment of the present invention, the olefin copolymers in the surface layer, the intermediate layer, and the inner layer are of the same type; the polyethylene-ester copolymers in the surface layer, the intermediate layer, and the inner layer are of the same type.

[0015] In a specific embodiment of the present invention, the amount of the olefin copolymer in the surface layer is 72% to 80% of the total mass of the olefin copolymer and the polyethylene-ester copolymer.

[0016] In a specific embodiment of the present invention, the amount of the olefin copolymer in the intermediate layer is 45% to 55% of the total mass of the olefin copolymer and the polyethylene-ester copolymer.

[0017] In a specific embodiment of the present invention, the amount of the olefin copolymer in the inner layer is 30% to 40% of the total mass of the olefin copolymer and the polyethylene-ester copolymer.

[0018] In a specific embodiment of the present invention, the crosslinking sensitizer includes at least one selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylperoxy-3,5,5-trimethylhexanoate, triallyl isocyanate, 4,4-di(tert-pentylperoxy)valerate, tert-butyl peroxy-2-ethylhexyl carbonate, and ethyl 3,3-di(tert-butylperoxy)butyrate.

[0019] In a specific embodiment of the present invention, the crosslinking agent includes at least one of tri(2-hydroxyethyl) isocyanurate triacrylate, trimethylolpropane triacrylate, triallyl cyanurate, triallyl isocyanurate, pentaerythritol triacrylate, and ethoxylated trimethylolpropane triacrylate.

[0020] In a specific embodiment of the present invention, the maleic anhydride-modified polyethylene-ester copolymer includes at least one selected from maleic anhydride-modified polyethylene-vinyl acetate copolymer, maleic anhydride-modified polyethylene-methyl acrylate copolymer, maleic anhydride-modified polyethylene-ethyl acrylate copolymer, and maleic anhydride-modified polyethylene-butyl acrylate copolymer. Further, in the maleic anhydride-modified polyethylene-ester copolymer, the grafting rate of maleic anhydride is 0.5 wt% to 2 wt%.

[0021] In a specific embodiment of the present invention, the total thickness of the polyolefin functional adhesive film is 0.15–0.4 mm. Further, in the polyolefin functional adhesive film, the thickness of the surface layer accounts for 25%–50% of the total thickness of the polyolefin functional adhesive film; the thickness of the intermediate layer accounts for 40%–70% of the total thickness of the polyolefin functional adhesive film; and the thickness of the inner layer accounts for 5%–10% of the total thickness of the polyolefin functional adhesive film.

[0022] The second aspect of the present invention provides a method for preparing a polyolefin functional adhesive film according to the first aspect of the present invention, comprising the following steps: performing multilayer co-extrusion of the raw materials of the surface layer, the raw materials of the intermediate layer and the raw materials of the inner layer, and then subjecting one side of the surface layer of the co-extruded film to electron beam irradiation treatment to obtain the polyolefin functional adhesive film.

[0023] In a specific embodiment of the present invention, during the electron beam irradiation treatment, the surface layer is cross-linked, while the intermediate layer and the inner layer are not cross-linked; the pre-cross-linking degree of the surface layer is >5%. Further, during the electron beam irradiation treatment, the irradiation dose is 100–180 kGy.

[0024] The third aspect of the present invention provides the application of the polyolefin functional adhesive film of the first aspect of the present invention in the corrosion protection of outdoor metal materials.

[0025] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0026] (1) Through a multi-layer structure design, the present invention enables the polyolefin functional adhesive film to have both excellent adhesive performance and weather resistance. Specifically, the inner layer gives the adhesive film adhesive function, which can ensure a long-lasting bond with metal. The surface layer has heat resistance and hardness, giving the adhesive film excellent weather resistance. The middle layer can not only achieve a reliable connection between the surface layer and the inner layer, but also protect the inner layer and the metal material from ultraviolet corrosion and aging. The polyolefin functional adhesive film obtained in this way solves the key performance problems faced by existing polyolefin films in outdoor metal anti-corrosion applications.

[0027] (2) In the preparation of the polyolefin functional adhesive film of the present invention, multi-layer co-extrusion and irradiation crosslinking are combined. The crosslinking structure and degree of crosslinking of polyolefin are controlled by irradiation treatment and raw material ratio. The surface layer of the irradiated polyolefin functional adhesive film is crosslinked, while the middle layer and inner layer are not crosslinked. The middle layer can play a stable self-supporting role. The film does not have obvious wrinkling and shrinkage before and after irradiation treatment, ensuring the surface flatness and aesthetics of the film product. Attached Figure Description

[0028] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the drawings used in the description of the specific embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained from these drawings without creative effort.

[0029] Figure 1 This is a schematic diagram of the structure of the polyolefin functional adhesive film provided in an embodiment of the present invention.

[0030] Figure label:

[0031] 1-Surface layer; 2-Middle layer; 3-Inner layer. Detailed Implementation

[0032] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. 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. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0033] In the description of this invention, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," and "outer," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are used only for the convenience of describing the invention and for simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the invention. Furthermore, the terms "first," "second," and "third" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0034] The first aspect of this invention provides a polyolefin functional adhesive film. Figure 1 This is a schematic diagram of the structure of the polyolefin functional adhesive film provided in an embodiment of the present invention; as shown. Figure 1 As shown, the polyolefin functional adhesive film provided by the present invention includes a surface layer 1, a middle layer 2 and an inner layer 3 stacked sequentially along its thickness direction.

[0035] Surface layer 1 comprises the following components by weight: 70-80 parts of olefin copolymer, 15-30 parts of polyethylene-ester copolymer, 0.5-2 parts of crosslinking sensitizer, 0.1-0.3 parts of co-crosslinking agent, 0.1-1 parts of antioxidant, and 0.1-0.2 parts of light stabilizer;

[0036] The intermediate layer 2 comprises the following components by weight: 40-50 parts of olefin copolymer, 35-55 parts of polyethylene-ester copolymer, 10-15 parts of titanium dioxide, 0.1-1 parts of antioxidant, and 0.1-0.2 parts of light stabilizer;

[0037] The inner layer 3 comprises the following components by weight: 10 to 30 parts of olefin copolymer, 40 to 70 parts of polyethylene-ester copolymer, and 20 to 40 parts of maleic anhydride-modified polyethylene-ester copolymer.

[0038] This invention, through a multi-layered structural design, enables polyolefin functional adhesive films to possess both excellent adhesive performance and weather resistance. Specifically, by adjusting the components of each layer, the inner layer imparts adhesive function to the film, ensuring durable adhesion to metals; the surface layer possesses heat resistance and hardness, giving the film excellent weather resistance; the middle layer not only achieves a reliable connection between the surface and inner layers but also protects the inner layer and metal materials from UV corrosion and aging. The resulting polyolefin functional adhesive film solves the key performance problems faced by existing polyolefin films in outdoor applications.

[0039] In different embodiments, the amounts of each component in surface layer 1, by weight, can be as follows: the amount of olefin copolymer can be 70 parts, 72 parts, 75 parts, 78 parts, 80 parts, or any combination thereof; the amount of polyethylene-ester copolymer can be 15 parts, 18 parts, 20 parts, 22 parts, 25 parts, 28 parts, 30 parts, or any combination thereof; and the amount of crosslinking sensitizer can be 0.5 parts, 0.8 parts, 1 part, 1.2 parts, 1.5 parts, etc. The amounts of the components in the surface layer can be 1 part, 1.8 parts, 2 parts, or any combination thereof; the amounts of the co-crosslinking agent can be 0.1 parts, 0.15 parts, 0.2 parts, 0.25 parts, 0.3 parts, or any combination thereof; the amounts of the antioxidant can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof; the amounts of the light stabilizer can be 0.1 parts, 0.12 parts, 0.15 parts, 0.18 parts, 0.2 parts, or any combination thereof. By controlling the amounts of each component in the surface layer within the above ranges, and in conjunction with irradiation treatment during the preparation process, the surface layer can be coordinated with the other layers to improve the adhesive properties, mechanical properties, and weather resistance of the polyolefin functional adhesive film.

[0040] In different embodiments, the amounts of each component in the intermediate layer 2, by weight, can be as follows: the amount of olefin copolymer can be 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, or any combination thereof; the amount of polyethylene-ester copolymer can be 35 parts, 38 parts, 40 parts, 42 parts, 45 parts, 48 ​​parts, 50 parts, 52 parts, 55 parts, or any combination thereof; the amount of titanium dioxide can be 10 parts, 11 parts, 12 parts, 13 parts, 14 parts, 15 parts, or any combination thereof; the amount of antioxidant can be 0.1 parts, 0.3 parts, 0.5 parts, 0.8 parts, 1 part, or any combination thereof; and the amount of light stabilizer can be 0.1 parts, 0.12 parts, 0.15 parts, 0.18 parts, 0.2 parts, or any combination thereof. By adjusting the amount of each component in the intermediate layer within the above range, it can work in conjunction with the surface layer and the inner layer to improve the reliability of the connection between the surface layer and the inner layer, and give full play to their supporting role, so that the film will not show obvious wrinkling and shrinkage after irradiation crosslinking.

[0041] In different embodiments, the amounts of each component in the inner layer 3, by weight, can be as follows: the amount of the olefin copolymer can be 10 parts, 15 parts, 20 parts, 25 parts, 30 parts, or any combination thereof; the amount of the polyethylene-ester copolymer can be 40 parts, 45 parts, 50 parts, 55 parts, 60 parts, 65 parts, 70 parts, or any combination thereof; and the amount of the maleic anhydride-modified polyethylene-ester copolymer can be 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, or any combination thereof. Under hot-pressing conditions, the inner layer of this invention can form a reliable and durable bond with metal materials. By controlling the amounts of each component in the inner layer within the above ranges, durable adhesion to metal materials can be maintained, and it can also be combined with other layers to improve the mechanical properties and weather resistance of the polyolefin functional adhesive film.

[0042] In a specific embodiment of the present invention, the olefin copolymer in the surface layer, the olefin copolymer in the intermediate layer, and the olefin copolymer in the inner layer are each independently selected from at least one of polyethylene-propylene copolymer, polyethylene-butene copolymer, polyethylene-octene copolymer, and amorphous α-olefin copolymer.

[0043] In a specific embodiment of the present invention, the polyethylene-ester copolymer in the surface layer, the polyethylene-ester copolymer in the middle layer, and the polyethylene-ester copolymer in the inner layer are each independently selected from at least one of polyethylene-vinyl acetate copolymer, polyethylene-methyl acrylate copolymer, polyethylene-ethyl acrylate copolymer, and polyethylene-butyl acrylate copolymer.

[0044] In a specific embodiment of the present invention, the olefin copolymers in the surface layer, the intermediate layer, and the inner layer are of the same type; the polyethylene-ester copolymers in the surface layer, the intermediate layer, and the inner layer are also of the same type. When the base resins in each layer are of different types, the difference in cooling and crystallization rates of the base resins in different layers during co-extrusion film formation is too large, resulting in significant internal stress after the film has cooled and solidified, causing the film to exhibit macroscopic curling and affecting normal use.

[0045] In a specific embodiment of the present invention, in the surface layer, the amount of olefin copolymer is 72% to 80% of the total mass of the olefin copolymer and the polyethylene-ester copolymer, such as 72% to 75%; in the intermediate layer, the amount of olefin copolymer is 45% to 55% of the total mass of the olefin copolymer and the polyethylene-ester copolymer, such as 48% to 52%; and in the inner layer, the amount of olefin copolymer is 30% to 40% of the total mass of the olefin copolymer and the polyethylene-ester copolymer, such as 32% to 36%. In the polyolefin functional adhesive film of the present invention, the amounts of olefin copolymer in the surface layer, intermediate layer, and inner layer each meet certain ranges, which helps to coordinate and control the appropriate cooling crystallization rate of each layer during the co-extrusion film formation process, ensuring the matching of each layer, and is more conducive to obtaining a good balance between the mechanical properties, adhesive properties, and smoothness of the adhesive film.

[0046] In a specific embodiment of the present invention, the crosslinking sensitizer includes at least one selected from 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylperoxy-3,5,5-trimethylhexanoate, triallyl isocyanate, 4,4-di(tert-pentylperoxy)valerate, tert-butyl peroxy-2-ethylhexyl carbonate, and ethyl 3,3-di(tert-butylperoxy)butyrate.

[0047] In a specific embodiment of the present invention, the co-crosslinking agent includes at least one of tris(2-hydroxyethyl)isocyanurate triacrylate, trimethylolpropane triacrylate, triallyl cyanurate, triallyl isocyanurate, pentaerythritol triacrylate, and ethoxylated trimethylolpropane triacrylate.

[0048] In a specific embodiment of the present invention, the maleic anhydride-modified polyethylene-ester copolymer includes at least one selected from maleic anhydride-modified polyethylene-vinyl acetate copolymer, maleic anhydride-modified polyethylene-methyl acrylate copolymer, maleic anhydride-modified polyethylene-ethyl acrylate copolymer, and maleic anhydride-modified polyethylene-butyl acrylate copolymer. Further, in the maleic anhydride-modified polyethylene-ester copolymer, the grafting rate of maleic anhydride is 0.5 wt% to 2 wt%.

[0049] In a specific embodiment of the present invention, the total thickness of the polyolefin functional adhesive film is 0.15–0.4 mm, such as 0.15 mm, 0.2 mm, 0.25 mm, 0.3 mm, 0.35 mm, 0.4 mm, or any combination thereof. Further, in the polyolefin functional adhesive film, the thickness of the surface layer accounts for 25%–50% of the total thickness of the polyolefin functional adhesive film, such as 25%, 30%, 35%, 40%, 45%, 50%, or any combination thereof; the thickness of the intermediate layer accounts for 40%–70% of the total thickness of the polyolefin functional adhesive film, such as 40%, 45%, 50%, 55%, 60%, 65%, 70%, or any combination thereof; and the thickness of the inner layer accounts for 5%–10% of the total thickness of the polyolefin functional adhesive film, such as 5%, 6%, 7%, 8%, 9%, 10%, or any combination thereof.

[0050] In a specific embodiment of the present invention, the light stabilizer in the surface layer and the light stabilizer in the intermediate layer are each independently selected from at least one of poly(4-hydroxy-2,2,6,6-tetramethyl-1-piperidinol) ester, poly-{[6-[(1,1,3,3,-tetramethylbutyl)-imino]-1,3,5,-triazine-2,4-diyl][2-(2,2,6,6,-tetramethylpiperidinyl)-subamino-hexamethylene-[4-(2,2,6,6,-tetramethylpiperidinyl)-subamino]] and bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate.

[0051] In a specific embodiment of the present invention, the antioxidant in the surface layer and the antioxidant in the intermediate layer are each independently selected from at least one of antioxidant B215, antioxidant B245 and antioxidant 1010.

[0052] The second aspect of the present invention provides a method for preparing a polyolefin functional adhesive film according to the first aspect of the present invention, comprising the following steps: performing multilayer co-extrusion of the raw materials of the surface layer, the raw materials of the intermediate layer and the raw materials of the inner layer, and then subjecting one side of the surface layer of the co-extruded film to electron beam irradiation treatment to obtain a polyolefin functional adhesive film.

[0053] In the preparation of the polyolefin functional adhesive film of the present invention, electron beam irradiation treatment is used. The high-energy electron beam deionizes and excites the polymer chains, causing them to recombine and crosslink, forming an entangled three-dimensional network structure. This results in a film with enhanced mechanical properties and weather resistance after irradiation treatment. Furthermore, the preparation method of the present invention is simple to operate, environmentally friendly, and cost-controllable, which is conducive to the industrial production of polyolefin functional adhesive films.

[0054] In a specific embodiment of the present invention, the extrusion temperature is set to 160–210 °C during multi-layer co-extrusion. Conventional multi-layer co-extrusion equipment can be used, and the extrusion temperature can be adjusted accordingly.

[0055] In a specific embodiment of the present invention, during electron beam irradiation treatment, the surface layer undergoes cross-linking, while the intermediate and inner layers do not; the pre-cross-linking degree of the surface layer is >5%. Further, the pre-cross-linking degree of the surface layer is 8% to 50%, preferably 10% to 30%, for example, it can be a range of 10%, 15%, 20%, 25%, 30%, or any combination thereof. Within this range, the surface layer of the film has certain strength and heat resistance, while avoiding excessive irradiation that could lead to degradation of the polymer chains.

[0056] In a specific embodiment of the present invention, the electron acceleration energy level in the electron beam irradiation treatment is 0.15–2 MeV, the irradiation dose is 100–180 kGy, and the irradiation rate is 10–250 m / min.

[0057] The electron beam irradiation treatment of the present invention can be carried out in an air atmosphere at room temperature (e.g., 25°C).

[0058] In a specific embodiment of the present invention, the raw materials are separately formulated into a surface layer, a middle layer, and an inner layer, mixed, and then extruded and granulated to obtain the raw materials for the surface layer, the middle layer, and the inner layer, respectively. Further, the extrusion granulation temperature is 180–210°C. Specifically, the extrusion granulation can be performed using a conventional twin-screw extruder, and the extrusion granulation temperature can be adjusted conventionally.

[0059] A third aspect of this invention provides the application of the polyolefin functional adhesive film of the first aspect of this invention in the corrosion protection of outdoor metal materials. The metal materials include, but are not limited to, galvanized steel sheets.

[0060] Example 1

[0061] This embodiment provides a polyolefin functional adhesive film, comprising a surface layer, a middle layer and an inner layer stacked sequentially along its thickness direction.

[0062] The surface layer comprises the following components by weight: 72 parts olefin copolymer, 26 parts polyethylene-ester copolymer, 1.5 parts crosslinking sensitizer, 0.1 parts co-crosslinking agent, 0.2 parts antioxidant, and 0.2 parts light stabilizer. The intermediate layer comprises the following components by weight: 45 parts olefin copolymer, 44 parts polyethylene-ester copolymer, 10.7 parts titanium dioxide, 0.2 parts antioxidant, and 0.1 parts light stabilizer. The inner layer comprises the following components by weight: 25 parts olefin copolymer, 48 parts polyethylene-ester copolymer, and 26.3 parts maleic anhydride-modified polyethylene-ester copolymer.

[0063] Among them, the olefin copolymers of the surface layer, intermediate layer and inner layer are all polyethylene-propylene copolymers (Sinopec PPB-M09), the polyethylene-ester copolymers of the surface layer, intermediate layer and inner layer are all polyethylene-vinyl acetate copolymers (Formosa Plastics EVA7320M), the crosslinking sensitizer of the surface layer is tert-butyl peroxide-3,5,5-trimethylhexanoate, the co-crosslinking agent of the surface layer is trimethylolpropane triacrylate, the antioxidants of the surface layer and intermediate layer are both B215, the light stabilizers of the surface layer and intermediate layer are both bis(2,2,6,6-tetramethyl-4-piperidinyl) sebacate, the titanium dioxide of the intermediate layer is color masterbatch (Meililian RCL-69), and the maleic anhydride modified polyethylene-ester copolymer of the inner layer is maleic anhydride modified polyethylene-vinyl acetate copolymer (Guangzhou Lushan New Material Co., Ltd., OV-1).

[0064] The preparation method of the polyolefin functional adhesive film in this embodiment includes the following steps:

[0065] (1) The raw materials for the surface layer, intermediate layer, and inner layer were respectively formulated and extruded and granulated using a twin-screw extruder to obtain surface granules, intermediate layer granules, and inner layer granules respectively; wherein, the temperatures of the first to sixth zones of the surface granule extruder were 60~80℃, 80~100℃, 100~120℃, 120~160℃, 160~180℃, and 180~210℃ respectively, and the die head temperature was set to 200℃; the temperature of the intermediate layer granule extruder was set to 200℃ in zone one. The temperatures in zones one through six of the inner layer granule extruder are 60–80℃, 80–100℃, 100–120℃, 120–160℃, 160–180℃, and 180–210℃, respectively, with the die temperature set to 200℃.

[0066] (2) The surface granules, intermediate granules and inner granules are co-extruded in multiple layers and cooled to form a film; then one side of the surface layer is subjected to electron beam irradiation treatment to obtain a polyolefin functional adhesive film.

[0067] In step (2), during multilayer co-extrusion, the extrusion temperature range of the surface, intermediate, and inner layers of the three-layer extruder is set to 180–210°C, and the co-extrusion die temperature is 200°C. The total thickness of the polyolefin functional adhesive film is 300 μm, and the thicknesses of the surface, intermediate, and inner layers are 90 µm, 180 µm, and 30 µm, respectively. During single-sided electron beam irradiation, the energy level of the electron accelerator is 0.16 MeV, the irradiation dose is 120 kGy, and the irradiation rate is 20 m / min. After single-sided electron beam irradiation, the crosslinking degree of the surface layer is 10%, and no crosslinking occurs in the intermediate and inner layers.

[0068] Example 2

[0069] This embodiment refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the only difference being the amount of raw materials used in the surface layer, the middle layer, and the inner layer. All other aspects are the same as in Example 1. Specific differences are as follows.

[0070] In this embodiment, the raw materials for the surface layer include the following components by weight: 80 parts of olefin copolymer, 16.5 parts of polyethylene-ester copolymer, 2 parts of crosslinking sensitizer, 0.3 parts of co-crosslinking agent, 1 part of antioxidant, and 0.2 parts of light stabilizer;

[0071] The raw materials for the intermediate layer include the following components by weight: 40 parts olefin copolymer, 49 parts polyethylene-ester copolymer, 10.7 parts titanium dioxide, 0.2 parts antioxidant, and 0.1 parts light stabilizer;

[0072] The inner layer consists of the following components by weight: 10 parts olefin copolymer, 70 parts polyethylene-ester copolymer, and 20 parts maleic anhydride-modified polyethylene-ester copolymer.

[0073] Example 3

[0074] This embodiment refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the only difference being the amount of raw materials used in the surface layer, the middle layer, and the inner layer. All other aspects are the same as in Example 1. Specific differences are as follows.

[0075] In this embodiment, the raw materials for the surface layer include the following components by weight: 70 parts of olefin copolymer, 29.2 parts of polyethylene-ester copolymer, 0.5 parts of crosslinking sensitizer, 0.1 parts of co-crosslinking agent, 0.1 parts of antioxidant and 0.1 parts of light stabilizer.

[0076] The raw materials for the intermediate layer include the following components by weight: 50 parts of olefin copolymer, 35 parts of polyethylene-ester copolymer, 14.7 parts of titanium dioxide, 0.2 parts of antioxidant and 0.1 parts of light stabilizer.

[0077] The inner layer consists of the following components by weight: 30 parts olefin copolymer, 40 parts polyethylene-ester copolymer, and 30 parts maleic anhydride-modified polyethylene-ester copolymer.

[0078] Example 4

[0079] This embodiment refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the only difference being that some parameters of the electron beam single-sided irradiation treatment in the preparation of the polyolefin functional adhesive film are different, while the rest are the same as in Example 1. The specific differences are as follows.

[0080] In this embodiment, the electron beam irradiation dose was 160 kGy during single-sided electron beam irradiation. After single-sided electron beam irradiation, the surface crosslinking degree was 50%, while no crosslinking occurred in the intermediate and inner layers.

[0081] Example 5

[0082] This embodiment refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the only difference being that some parameters of the electron beam single-sided irradiation treatment in the preparation of the polyolefin functional adhesive film are different, while the rest are the same as in Example 1. The specific differences are as follows.

[0083] In this embodiment, the electron beam irradiation dose was 140 kGy during single-sided electron beam irradiation. After single-sided electron beam irradiation, the surface crosslinking degree was 30%, while no crosslinking occurred in the intermediate and inner layers.

[0084] Example 6 group

[0085] This example group refers to the polyolefin functional adhesive film and its preparation method of Example 1, with the only difference being the amount of raw material used in the surface layer; all other aspects are the same as in Example 1. The specific differences are as follows.

[0086] Example 6a: The raw material for the surface layer includes the following components by weight: 80 parts of olefin copolymer, 18 parts of polyethylene-ester copolymer, 1.5 parts of crosslinking sensitizer, 0.1 parts of co-crosslinking agent, 0.2 parts of antioxidant and 0.2 parts of light stabilizer;

[0087] Example 6b: The raw material for the surface layer includes the following components by weight: 70 parts of olefin copolymer, 28 parts of polyethylene-ester copolymer, 1.5 parts of crosslinking sensitizer, 0.1 parts of co-crosslinking agent, 0.2 parts of antioxidant and 0.2 parts of light stabilizer.

[0088] Example 7 group

[0089] This example group refers to the polyolefin functional adhesive film and its preparation method of Example 1, with the only difference being the amount of raw material used in the intermediate layer; all other aspects are the same as in Example 1. The specific differences are as follows.

[0090] Example 7a: The raw materials for the intermediate layer include the following components by weight: 50 parts of olefin copolymer, 39 parts of polyethylene-ester copolymer, 10.7 parts of titanium dioxide, 0.2 parts of antioxidant, and 0.1 parts of light stabilizer;

[0091] Example 7b: The raw materials for the intermediate layer include the following components by weight: 40 parts of olefin copolymer, 49 parts of polyethylene-ester copolymer, 10.7 parts of titanium dioxide, 0.2 parts of antioxidant and 0.1 parts of light stabilizer.

[0092] Example 8 group

[0093] This example group refers to the polyolefin functional adhesive film and its preparation method of Example 1, with the only difference being the amount of raw material used in the inner layer; all other aspects are the same as in Example 1. The specific differences are as follows.

[0094] Example 8a: The raw material of the inner layer includes the following components by weight: 30 parts of olefin copolymer, 43 parts of polyethylene-ester copolymer and 26.3 parts of maleic anhydride modified polyethylene-ester copolymer;

[0095] Example 8b: The raw materials for the inner layer include the following components by weight: 21 parts of olefin copolymer, 52 parts of polyethylene-ester copolymer and 26.3 parts of maleic anhydride-modified polyethylene-ester copolymer.

[0096] Example 9

[0097] This set of examples refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the only difference being the type of olefin copolymer in the intermediate layer; all other aspects are the same as in Example 1. Specific differences are as follows.

[0098] The type of olefin copolymer in the intermediate layer of this embodiment is an amorphous α-olefin copolymer (Hunsman APAORT52627).

[0099] Comparative Example 1

[0100] Comparative Example 1 refers to the polyolefin functional adhesive film and its preparation method in Example 1, with the difference being: it does not include the surface structure; after cooling and film formation, one side of the intermediate layer is subjected to single-sided electron beam irradiation treatment; the thickness of the polyolefin functional adhesive film is 210 μm.

[0101] Comparative Example 2

[0102] Comparative Example 2 refers to the polyolefin functional adhesive film and its preparation method of Example 1, with the difference being: the amount of raw materials used in the surface layer is different, the electron irradiation dose is different, and everything else is the same as in Example 1. The specific differences are as follows.

[0103] In Comparative Example 2, the surface layer raw material comprised the following components by weight: 72 parts olefin copolymer, 26 parts polyethylene-ester copolymer, 0.2 parts antioxidant, and 0.2 parts light stabilizer. The surface layer raw material in Comparative Example 2 did not include crosslinking sensitizers or co-crosslinking agents. The electron irradiation dose was 160 kGy.

[0104] Comparative Example 3

[0105] Comparative Example 3 refers to the polyolefin functional adhesive film and its preparation method in Example 1, the difference being that: in step (2) of the preparation of the adhesive film, after cooling and forming the film, no single-sided electron beam irradiation treatment is performed.

[0106] Comparative Example 4

[0107] Comparative Example 4 refers to the polyolefin functional adhesive film and its preparation method of Comparative Example 1. The difference is that in step (2) of the preparation of the adhesive film, after cooling and film formation, single-sided electron beam irradiation treatment is not performed.

[0108] Comparative Example 5

[0109] Comparative Example 5 refers to the polyolefin functional adhesive film and its preparation method of Comparative Example 2. The difference is that in step (2) of the preparation of the adhesive film, after cooling and forming the film, single-sided electron beam irradiation treatment is not performed.

[0110] Comparative Example 6

[0111] Comparative Example 6 refers to the polyolefin functional adhesive film and its preparation method of Example 1, the difference being that the amount of raw materials used in the surface layer and intermediate layer are different, while the rest are the same as in Example 1. The specific differences are as follows.

[0112] In Comparative Example 6, the surface layer raw materials included the following components by weight: 98 parts of polyethylene-ester copolymer (Formosa Plastics EVA 7320M), 1.5 parts of crosslinking sensitizer, 0.1 parts of co-crosslinking agent, 0.2 parts of antioxidant, and 0.2 parts of light stabilizer; the intermediate layer raw materials included the following components by weight: 89 parts of polyethylene-ester copolymer (Formosa Plastics EVA 7320M), 10.7 parts of titanium dioxide, 0.2 parts of antioxidant, and 0.1 parts of light stabilizer. The surface and intermediate layer raw materials in this comparative example did not include olefin copolymers.

[0113] Comparative Example 7

[0114] Comparative Example 7 refers to the polyolefin functional adhesive film and its preparation method of Example 1, the difference being that the amount of raw material used in the intermediate layer is different, while the rest are the same as in Example 1. The specific differences are as follows.

[0115] In Comparative Example 7, the intermediate layer raw materials included the following components by weight: 89 parts of polyethylene-ester copolymer (Formosa Plastics EVA 7320M), 10.7 parts of titanium dioxide, 0.2 parts of antioxidant, and 0.1 parts of light stabilizer. The intermediate layer raw materials in this comparative example did not include olefin copolymers.

[0116] Experimental Example

[0117] The adhesive films prepared in different embodiments and comparative examples were tested as follows, and the test results are shown in Table 1.

[0118] Test items:

[0119] 1. Appearance flatness: The adhesive films prepared in different embodiments and comparative examples are cut into 3 cm × 3 cm samples. The films are placed on a smooth surface, and the height difference between the two ends of the film is measured with a ruler to reflect the curvature of the film. If the height difference between the two ends is less than 1 mm, it is recorded as flat; if the height difference between the two ends is greater than or equal to 1 mm and less than 3 mm, it is recorded as slightly curled; if the height difference between the two ends is greater than or equal to 3 mm, it is recorded as severely curled.

[0120] 2. Tensile strength and elongation at break: Tensile tests were conducted on the adhesive films prepared in different embodiments and comparative examples in accordance with GB / T 1040.3-2006 standard.

[0121] 3. Surface Heat Resistance: The adhesive films prepared in different embodiments and comparative examples were cut into rectangular samples of 2 cm × 10 cm. The samples were stretched taut so that the surface of the middle part was in contact with a 150°C hot steel roller for 1 second. The width X cm of the sample after contact with the hot steel roller was measured. The shrinkage rate of the sample was calculated according to the formula (2-X) / 2. If the shrinkage rate is less than 5%, it is recorded as no deformation; if the shrinkage rate is greater than or equal to 5% and less than 10%, it is recorded as slight shrinkage; if the shrinkage rate is greater than or equal to 10% and less than 30%, it is recorded as deformation; if the adhesive film shrinks and melts directly, almost breaks or breaks, it is recorded as severe deformation.

[0122] 4. Peel strength: The adhesive films prepared in different embodiments and comparative examples were bonded to galvanized sheets at 150℃ under 0.3MPa roller pressure to form a two-layer composite structure (adhesive film-galvanized sheet). The composite samples were cut into rectangular strips of 25mm×150mm and peel tests were performed on the composite samples according to GB / T 2790-1995 standard.

[0123] Table 1 Test results of different adhesive films

[0124]

[0125] The test results above show that this invention, through its multi-layer structure design and electron beam irradiation treatment to regulate the surface cross-linking degree, effectively improves the mechanical strength and surface heat resistance of the adhesive film, while not affecting the bonding strength between the film and the metal material. Therefore, it can be applied to the field of outdoor engineering metal material protection. Furthermore, the polyolefin functional adhesive film preparation method of this invention is simple to operate, environmentally friendly, cost-controllable, and can achieve continuous industrial production.

[0126] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them. Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features therein. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A polyolefin functional adhesive film, characterized by, The surface layer, the intermediate layer and the inner layer are sequentially stacked along the thickness direction; The surface layer comprises the following components in parts by weight: 70-80 parts of olefin copolymer, 15-30 parts of polyethylene-ester copolymer, 0.5-2 parts of crosslinking sensitizer, 0.1-0.3 parts of crosslinking assistant, 0.1-1 parts of antioxidant and 0.1-0.2 parts of light stabilizer; The intermediate layer comprises the following components in parts by weight: 40-50 parts of olefin copolymer, 35-55 parts of polyethylene-ester copolymer, 10-15 parts of titanium white, 0.1-1 parts of antioxidant and 0.1-0.2 parts of light stabilizer; The inner layer comprises the following components in parts by weight: 10-30 parts of olefin copolymer, 40-70 parts of polyethylene-ester copolymer and 20-40 parts of maleic anhydride modified polyethylene-ester copolymer; The olefin copolymer in the surface layer, the olefin copolymer in the intermediate layer and the olefin copolymer in the inner layer are each independently selected from at least one of polyethylene-propylene copolymer, polyethylene-butene copolymer, polyethylene-octene copolymer and amorphous α-olefin copolymer; The polyethylene-ester copolymer in the surface layer, the polyethylene-ester copolymer in the intermediate layer and the polyethylene-ester copolymer in the inner layer are each independently selected from at least one of polyethylene-vinyl acetate copolymer, polyethylene-methyl acrylate copolymer, polyethylene-ethyl acrylate copolymer and polyethylene-butyl acrylate copolymer; The surface layer is subjected to electron beam irradiation treatment, and the pre-crosslinking degree of the surface layer in the electron beam irradiation treatment is 10%-25%.

2. The polyolefin functional adhesive film according to claim 1, characterized in that, The types of the olefin copolymer in the surface layer, the olefin copolymer in the intermediate layer and the olefin copolymer in the inner layer are the same; the types of the polyethylene-ester copolymer in the surface layer, the polyethylene-ester copolymer in the intermediate layer and the polyethylene-ester copolymer in the inner layer are the same.

3. The polyolefin functional adhesive film according to claim 1, wherein At least one of the following characteristics is possessed: (1) In the surface layer, the amount of the olefin copolymer is 72%-80% of the mass sum of the olefin copolymer and the polyethylene-ester copolymer; (2) In the intermediate layer, the amount of the olefin copolymer is 45%-55% of the mass sum of the olefin copolymer and the polyethylene-ester copolymer; (3) In the inner layer, the amount of the olefin copolymer is 30%-40% of the mass sum of the olefin copolymer and the polyethylene-ester copolymer.

4. The polyolefin functional adhesive film according to claim 1, wherein At least one of the following characteristics is possessed: (1) The crosslinking sensitizer comprises at least one of 2,5-dimethyl-2,5-di(tert-butylperoxy)hexane, tert-butylperoxide-3,5,5-trimethylhexanoate, triallyl isocyanate, 4,4-di(tert-pentylperoxy)valeric acid n-butyl ester, tert-butyl peroxide 2-ethylhexyl carbonate and 3,3-di(tert-butylperoxy)butyric acid ethyl ester; (2) the co-crosslinking agent includes at least one of tris(2-hydroxyethyl) isocyanurate, trimethylolpropane triacrylate, triallyl cyanurate, triallyl isocyanurate, pentaerythritol triacrylate and ethoxylated trimethylolpropane triacrylate.

5. The polyolefin functional adhesive film according to claim 1, wherein At least one of the following characteristics is included: (1) the maleic anhydride modified polyethylene-ester copolymer includes at least one of maleic anhydride modified polyethylene-vinyl acetate copolymer, maleic anhydride modified polyethylene-methyl acrylate copolymer, maleic anhydride modified polyethylene-ethyl acrylate copolymer and maleic anhydride modified polyethylene-butyl acrylate copolymer; (2) the grafting rate of maleic anhydride in the maleic anhydride modified polyethylene-ester copolymer is 0.5wt%-2wt%.

6. The polyolefin functional adhesive film according to claim 1, wherein The total thickness of the polyolefin functional adhesive film is 0.15-0.4mm; The thickness of the surface layer accounts for 25%-50% of the total thickness of the polyolefin functional adhesive film; The thickness of the intermediate layer accounts for 40%-70% of the total thickness of the polyolefin functional adhesive film; The thickness of the inner layer accounts for 5%-10% of the total thickness of the polyolefin functional adhesive film.

7. The method of producing a polyolefin functional adhesive film according to any one of claims 1 to 6, characterized by, The method includes the following steps: multi-layer co-extrusion of the raw materials of the surface layer, the raw materials of the intermediate layer and the raw materials of the inner layer, and electron beam irradiation treatment of the surface layer side of the multi-layer co-extruded film to obtain the polyolefin functional adhesive film.

8. The production method according to claim 7, characterized by, In the electron beam irradiation treatment, the irradiation dose is 100-180kGy.

9. Application of the polyolefin functional adhesive film of any one of claims 1-6 or the polyolefin functional adhesive film prepared by the method of any one of claims 7-8 in outdoor metal material corrosion prevention.

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