A film laminating composite device and a cross composite film production process

Abstract

This application relates to the field of building films, and discloses a film laminating composite device and a cross-laminated film production process, including the following steps: S1. Perform surface pretreatment on the main film substrate; S2. Prepare a dynamic reaction adhesion promoting layer coating solution; S3. Coat the dynamic reaction adhesion promoting layer on the surface of the main film substrate; S4. Multilayer composite the main film substrate, the dynamic reaction adhesion promoting layer, and the secondary film substrate through an extrusion coextrusion device; S5. Perform hot pressing and curing treatment on the composite film; S6. Wind up to obtain the finished product. The present invention adopts the technical solution of corona treatment for both the main film substrate and the secondary film substrate, introducing polar groups such as carboxyl groups and hydroxyl groups on the substrate surface, significantly improving the interfacial adhesion performance, achieving the effect of high peel strength of the multilayer composite film, and overcoming the problems of insufficient interfacial bonding strength and easy delamination of the multilayer film in high humidity and high temperature environments.

Description

Technical Field

[0001] The present invention relates to the technical field of building films, and specifically to a film laminating composite device and a cross-laminated film production process. Background Art

[0002] As a new type of functional film material widely used in the fields of packaging, construction, and industry, the cross-laminated film has certain mechanical strength, adhesion performance, and environmental adaptability due to its multi-layer composite structure. This film is usually made of substrates with different physical or chemical properties through a composite process. The typical production process includes substrate treatment, preparation and coating of the adhesion layer, extrusion compounding, and winding processes. In order to meet the actual application requirements, the production process of the cross-film needs to take into account the interfacial bonding force between different substrates, the thickness uniformity of the multi-layer film, and the consistency of surface properties.

[0003] Although the production technology of cross-laminated films has seen much development, there are still obvious deficiencies in the improvement of the interfacial bonding force of multi-layer films and the control of the structural uniformity of the film materials in the prior art. The surface pretreatment of the substrate is often disconnected from the composite process, resulting in unstable improvement of surface polarity and inability to form efficient interfacial chemical bonding. Secondly, the film material is easily affected by tension fluctuations during high-speed production, leading to a decrease in interfacial bonding force and the appearance of surface defects. Especially when used in humid and hot or high-stress environments, these film materials are more likely to exhibit problems such as delamination, warping, or breakage, thus affecting their long-term use performance. Summary of the Invention

[0004] Aiming at the deficiencies of the prior art, the present invention provides a film laminating composite device and a cross-laminated film production process, which solve the problems of insufficient interfacial bonding force of multi-layer films in the prior art, disconnection between the surface pretreatment of the substrate and the composite process, unstable performance caused by uneven distribution of the adhesion layer, and surface defects and delamination caused by tension fluctuations during high-speed production of the film material.

[0005] To achieve the above objectives, the present invention is realized through the following technical solutions: A cross-laminated film production process, including the following steps:

[0006] S1. Perform surface pretreatment on the main film substrate; the main film substrate is the basic layer of the entire cross-laminated film structure, and its main components are polyethylene (PE) or polypropylene (PP). Since PE and PP are non-polar materials with low surface energy and poor adhesion performance during direct compounding, surface pretreatment is required to increase surface polarity and interfacial energy to enhance its bonding force with the dynamic reaction adhesion promoting layer.

[0007] S2. Prepare the coating liquid for the dynamic reaction adhesion promoting layer; the coating liquid includes the following components:

[0008] Polyurethane (PU) or polyvinyl alcohol (PVA): As the matrix material, it provides good adhesion and dynamic crosslinking ability.

[0009] γ-aminopropyltriethoxysilane: As a self-assembled molecule, it forms silicon-oxygen bonds at the interface to enhance the adhesion strength.

[0010] Dihydroxybenzene: As a dynamic crosslinking agent, it improves the interface strength through dynamic chemical bonds (hydrogen bonds and π-π interactions).

[0011] Nanoscale few-layer graphene oxide (fGO) and functionalized silica (fSiO2): They improve the mechanical strength and interfacial bonding force of the coating through nano-enhancement.

[0012] Ethanol / water mixed solvent: It ensures the uniformity and dispersibility of the coating solution.

[0013] Dynamic crosslinking effect:

[0014] Dihydroxybenzene and the polyurethane matrix form chemical bonds at the composite interface through a reversible dynamic crosslinking reaction. This dynamic crosslinking can adapt to the thermal pressing and mechanical stresses during the composite process, thereby enhancing the adhesion performance.

[0015] Interface self-assembly:

[0016] γ-aminopropyltriethoxysilane reacts with the substrate surface through its triethoxy groups to form stable silicon-oxygen bonds (Si-O-Si), while its amino part binds to the polar groups in the dynamic reaction adhesion promoting layer to form a crosslinked network.

[0017] S3. Coating the dynamic reaction adhesion promoting layer onto the surface of the main film substrate; The dynamic reaction adhesion promoting layer is uniformly coated on the surface of the main film substrate that has been surface pretreated through a doctor blade coating or casting process. The coating thickness is controlled within 0.5 - 1.5 μm to ensure that it can cover the substrate surface without increasing the thickness of the composite film.

[0018] The coated dynamic reaction layer forms strong interfacial chemical bonds (silicon-oxygen bonds) with the substrate surface through self-assembled molecules (γ-aminopropyltriethoxysilane), further enhancing the adhesion force. In addition, the uniform distribution of nanoparticles can fill the microporous structure on the substrate surface, thereby improving the coating coverage effect and enhancing the overall adhesion performance.

[0019] S4. Multilayer composite of the main film substrate, the dynamic reaction adhesion promoting layer, and the secondary film substrate through an extrusion coextrusion device; The main film substrate, the dynamic reaction adhesion promoting layer, and the secondary film substrate are synchronously composite in the coextrusion device. The coextrusion device uses a multilayer coextrusion die head to enable the three-layer materials to fuse at the interface under high temperature and high pressure.

[0020] Interface chemical reaction:

[0021] Under the high-temperature conditions of extrusion coextrusion (main substrate: 190 - 250 °C, secondary substrate: 190 - 250 °C, interlayer: 150 - 200 °C), γ-aminopropyltriethoxysilane in the dynamic reaction adhesion promotion layer forms chemical bonds with the surface of the secondary film substrate. At the same time, dihydroxybenzene undergoes a dynamic crosslinking reaction with the polyurethane matrix to generate a crosslinked network structure, ensuring a high-strength binding force at the composite film interface.

[0022] S5. Subject the composite film to hot-press curing treatment; the composite film is cured through a hot-press curing device. The hot-press temperature is 120 - 150 °C, the pressure is 10 - 20 MPa, and the time is 5 - 10 minutes. Hot-press curing further completes the crosslinking reaction of the dynamic reaction adhesion promotion layer and enhances the overall strength of the film.

[0023] Under hot-press conditions, the dynamic crosslinking reaction between dihydroxybenzene in the dynamic reaction adhesion promotion layer and the polyurethane matrix proceeds fully, forming a stable three-dimensional crosslinked network structure.

[0024] γ-aminopropyltriethoxysilane further reacts with the substrate surface to form more siloxane bonds, improving the interfacial adhesion strength.

[0025] Under hot-press conditions, the nanomaterials can be more evenly distributed in the coating, optimizing the mechanical anchoring effect.

[0026] S6. Wind up to obtain the finished product; during the winding-up process, tension control ensures the flatness and thickness uniformity of the film, while avoiding interfacial separation or performance degradation caused by excessive stretching.

[0027] Among them, the main film substrate includes 80 - 95 parts by mass of polyethylene or polypropylene, 3 - 10 parts by mass of maleic anhydride grafted polymer, and 0.5 - 2 parts by mass of processing aids;

[0028] The dynamic reaction adhesion promotion layer includes 60 - 80 parts by mass of polyurethane or polyvinyl alcohol, 3 - 8 parts by mass of γ-aminopropyltriethoxysilane, 2 - 5 parts by mass of dihydroxybenzene, 3 - 6 parts by mass of nano-graphene oxide, 4 - 8 parts by mass of functionalized silica, and 10 - 20 parts by mass of ethanol / water mixed solvent;

[0029] The secondary film substrate includes 80 - 95 parts by mass of polyethylene or polypropylene, 3 - 10 parts by mass of maleic anhydride grafted polymer, and 0.5 - 2 parts by mass of processing aids.

[0030] Surface energy enhancement and interfacial polarization (S1): Corona treatment enhances the surface polarity of the substrate, providing a basis for chemical bonding force for the subsequent adhesion promotion layer.

[0031] Synergistic effect of dynamic crosslinking and self-assembly (S2 - S3): The dynamic reaction layer forms both chemical and physical bonds at the interface, enhancing the adhesion strength and interface stability.

[0032] Nano-enhancement and mechanical anchoring effect (S4): Nano-materials provide micro-embedding and enhancement in the interface layer, further improving the mechanical properties of the film.

[0033] Full reactivity of hot pressing and curing (S5): Under hot pressing and curing conditions, chemical crosslinking and molecular diffusion proceed fully, ensuring that the properties of the composite film reach the optimum.

[0034] Preferably, the method for surface pretreatment of the main film substrate in S1 includes low-temperature plasma treatment, with treatment parameters of power 40 - 80 W, treatment time 30 - 90 seconds, distance from the electrode 5 - 10 mm, and gas flow rate 20 - 50 sccm.

[0035] Surface polarity enhancement mechanism: Low-temperature plasma generates discharge phenomena through a high-voltage electric field, inducing physical and chemical changes on the surface of the main film substrate, including molecular chain breakage and free radical generation. These free radicals react with oxygen in an air or oxygen environment to form polar groups such as hydroxyl (-OH) and carboxyl (-COOH). The introduction of these polar groups enables the non-polar PE or PP surface to form stronger chemical and physical bonds with the subsequent dynamic reaction adhesion promotion layer.

[0036] Surface roughening mechanism: The micro-etching effect during corona discharge forms fine concave and convex structures on the substrate surface. This surface roughening not only increases the contact area between the coating layer and the substrate but also further enhances the adhesion force through the physical anchoring effect.

[0037] Preferably, the method for preparing the coating solution of the dynamic reaction adhesion promotion layer in S2 includes the following steps:

[0038] Dissolve polyurethane or polyvinyl alcohol in an ethanol / water mixed solvent;

[0039] Use a 1:1 ratio of ethanol and water mixed solvent to ensure that the solvent can fully dissolve polyurethane or polyvinyl alcohol.

[0040] Polyurethane is a high-molecular material with extremely high adhesion, while polyvinyl alcohol is known for its excellent polarity and chemical compatibility. Both can be used as the matrix materials for the dynamic reaction coating layer, providing a basis for interface adhesion.

[0041] Dissolution mechanism: The mixed solvent of ethanol and water can dissolve both the non-polar part (polyether segment) and the polar part (amino group, hydroxyl group) of polyurethane, ensuring that the polyurethane can be completely dissolved and form a homogeneous solution. The strong polar group (hydroxyl group) of polyvinyl alcohol has good compatibility with water, enabling it to dissolve rapidly.

[0042] Contribution to matrix properties: Polyurethane provides high elasticity and dynamic crosslinking ability in the coating layer, while the strong polarity and water solubility of polyvinyl alcohol can enhance the surface adhesion properties of the coating layer.

[0043] γ-aminopropyltriethoxysilane, dihydroxybenzene, nano-graphene oxide, and functionalized silica are added in sequence;

[0044] γ-aminopropyltriethoxysilane (3 - 8 parts by mass) is added to the solution first as a self-assembled molecule. Its triethoxy part forms silanol groups through hydrolysis and further forms silicon-oxygen bonds (Si-O-Si) with polyurethane or polyvinyl alcohol and the substrate surface.

[0045] Subsequently, dihydroxybenzene (2 - 5 parts by mass) is added as a dynamic crosslinking agent. Its hydroxyl group can undergo a dynamic chemical reaction with the carbonyl group in the polyurethane molecule to form a reversible crosslinked network.

[0046] In the third step, nano-graphene oxide (3 - 6 parts by mass) is added. Its surface is equipped with hydroxyl and carboxyl groups, which physically or chemically bond with the coating matrix, and simultaneously enhance the adhesion properties through its high specific surface area.

[0047] Finally, functionalized silica (4 - 8 parts by mass) is added. The surface of the silica modified by a silane coupling agent has polar groups (hydroxyl group, amino group), which can form chemical bonds with the coating matrix, fill interface defects, and provide mechanical reinforcement.

[0048] Self-assembly mechanism of γ-aminopropyltriethoxysilane: Triethoxysilane hydrolyzes in the solution to generate silanol groups, and the silanol combines with the hydroxyl groups on the substrate surface through a condensation reaction to form stable silicon-oxygen bonds (Si-O-Si), achieving chemical bonding. Meanwhile, its amino part can form hydrogen bonds with the polymer chains in the dynamic reaction layer, enhancing the interfacial bonding force.

[0049] Preferably, the method for coating the dynamic reaction adhesion promotion layer in S3 is a doctor blade coating or casting process, with a coating amount of 0.1 - 0.5 g / m 2 , a coating thickness of 0.5 - 1.5 μm, a preliminary drying temperature of 70 - 100 °C, and a drying time of 3 - 5 minutes.

[0050] Coating method: Doctor blade coating or casting process;

[0051] Doctor blade coating process:

[0052] Doctor blading is a simple and efficient coating method that enables precise coating control on the surface of the substrate through a doctor blade, suitable for fine control of the coating layer thickness, especially widely applied in large-scale production. By adjusting the clearance height of the doctor blade and the applied pressure, the coating liquid can be ensured to be evenly distributed on the surface of the substrate.

[0053] Cast process:

[0054] Cast coating is to evenly spread the coating liquid on the surface of the substrate and achieve thin-layer coating through the precise control of the coating device, suitable for processes with high requirements for coating uniformity.

[0055] Initial drying process: temperature 70 - 100 °C, time 3 - 5 minutes; the coated substrate is dried at an initial drying temperature of 70 - 100 °C for 3 - 5 minutes; this process aims to remove the solvents (ethanol and water) in the coating liquid, and at the same time enable the components (dihydroxybenzene, γ-aminopropyltriethoxysilane) in the adhesion promotion layer to complete partial chemical reactions.

[0056] Solvent evaporation mechanism: The mixed solvent of ethanol and water in the coating liquid rapidly evaporates at 70 - 100 °C, leaving solid components (such as polyurethane, nano-graphene oxide, etc.) evenly deposited on the surface of the substrate to form a preliminarily cured adhesion layer.

[0057] Chemical pre-reaction mechanism: During the drying process, γ-aminopropyltriethoxysilane in the coating layer undergoes hydrolysis to generate silanol (Si-OH) and further reacts with the surface of the substrate or the polyurethane / polyvinyl alcohol matrix to form siloxane bonds (Si-O-Si). At the same time, the hydroxyl groups of dihydroxybenzene also undergo preliminary hydrogen bonding or dynamic chemical bonding with the polar groups in the coating matrix, thereby enhancing the adhesion performance of the coating layer.

[0058] Preferably, the parameters of the co-extrusion process in S4 are as follows: the extrusion temperature of the main substrate layer is 190 - 250 °C, the extrusion temperature of the interlayer is 150 - 200 °C, the extrusion temperature of the secondary substrate layer is 190 - 250 °C, the extrusion speed is 100 - 150 m / min, and the pressure is 20 - 50 MPa.

[0059] Temperature control: main substrate layer 190 - 250 °C, interlayer 150 - 200 °C, secondary substrate layer 190 - 250 °C;

[0060] During the co-extrusion process, the temperature settings of each layer of material are the core parameters, and the temperature range needs to be precisely adjusted according to the melting characteristics of different materials:

[0061] Main substrate layer (PE or PP): A temperature range of 190 - 250 °C can ensure that it is in a molten flow state, thus achieving effective bonding with the adhesion layer during the extrusion process.

[0062] Dynamic reaction adhesion promotion interlayer: A temperature of 150 - 200 °C can not only maintain the fluidity of the coating layer, promote interfacial reactions, but also avoid decomposition caused by excessive temperature.

[0063] Secondary substrate layer (PE or PP): The temperature range is the same as that of the main substrate layer to ensure the final overall melt - compounding effect.

[0064] Dynamic reaction and chemical bonding mechanism: The dynamic cross - linker (dihydroxybenzene) in the adhesion promotion layer undergoes a chemical reaction with the substrate surface or adjacent substrates at a temperature of 150 - 200 °C to form a dynamic cross - linked network. In addition, the silanol groups of γ - aminopropyltriethoxysilane undergo a condensation reaction with the hydroxyl groups on the substrate surface or the groups in the dynamic reaction adhesion promotion layer to generate siloxane bonds (Si - O - Si), further enhancing the chemical bonding force.

[0065] Thermal diffusion mechanism: Under high - temperature conditions, thermal diffusion occurs between interfacial molecules, increasing the interpenetration and interlocking of molecular chains, and further enhancing the interfacial adhesion strength.

[0066] Extrusion speed: 100 - 150 m / min;

[0067] The extrusion speed determines the synchronous fluidity of the multi - layer materials and the compounding efficiency during the co - extrusion process. The preferred range of 100 - 150 m / min can not only meet the efficiency requirements of industrial production but also ensure sufficient bonding time for each layer of material at the interface.

[0068] Extrusion pressure: 20 - 50 MP;

[0069] The extrusion pressure is a key parameter to ensure the tight bonding of multi - layer materials in the die head. Too low pressure will result in insufficient bonding between materials and an increase in interfacial defects, while too high pressure will lead to insufficient material fluidity and delamination. The preferred range of 20 - 50 MPa can ensure that each layer of material is evenly stressed in the die head and achieve efficient bonding.

[0070] The compounding process in the multi - layer co - extrusion die head:

[0071] The multi - layer co - extrusion die head is the core device of this process. Its design enables the main substrate layer, the dynamic reaction adhesion promotion layer, and the secondary substrate layer to complete synchronous flow and compounding in the die head. By optimizing the flow channel design of the die head, the flow rates of each layer of material in the die head are made consistent to avoid uneven flow distribution.

[0072] Interface distribution uniformity mechanism: The design of the die runner ensures that each layer of material has the same flow rate and thickness distribution at the die outlet, thus avoiding thickness differences or delamination phenomena at the interface caused by uneven flow.

[0073] Lamination composite mechanism: The adhesion promotion layer forms a continuous intermediate layer at the interface through synchronous melting and flow with the main substrate and the secondary substrate in the die, enhancing the adhesion strength of the overall composite film.

[0074] Preferably, the parameters of hot pressing and curing in S5 are a hot pressing temperature of 120 - 150 °C, a pressure of 10 - 20 MPa, and a time of 5 - 10 minutes.

[0075] Hot pressing temperature: 120 - 150 °C The setting of the hot pressing temperature needs to meet the following requirements:

[0076] Ensure that the chemical reactions (dynamic crosslinking reaction, formation of silicon-oxygen bonds) in the dynamic reaction adhesion promotion layer are fully completed within the optimal temperature range;

[0077] At the same time, avoid thermal decomposition of the substrate or degradation of the coating layer performance caused by high temperature.

[0078] Dynamic crosslinking reaction mechanism: At a hot pressing temperature of 120 - 150 °C, the crosslinking agent (dihydroxybenzene) in the dynamic reaction adhesion promotion layer undergoes a reversible crosslinking reaction with the carbonyl or hydroxyl groups in the polyurethane or polyvinyl alcohol matrix. This dynamic crosslinking can form a three-dimensional crosslinked network structure at the interface, greatly improving the adhesion strength and interface stability.

[0079] Silicon-oxygen bond formation mechanism: The γ-aminopropyltriethoxysilane in the coating solution, at the hot pressing temperature, its incompletely reacted silanol groups (Si-OH) form more silicon-oxygen bonds (Si-O-Si) with the substrate surface or the dynamic reaction layer through further condensation reactions, thus significantly enhancing the interfacial chemical bonding force.

[0080] Hot pressing pressure: 10 - 20 MPa The main function of the hot pressing pressure is to achieve full contact of interfacial molecules through mechanical compression and compact the composite layer into a continuous and uniform overall structure.

[0081] Hot pressing time: 5 - 10 minutes The selection of the hot pressing time needs to ensure that the interfacial reaction is fully completed, while avoiding material thermal aging or performance degradation caused by too long a time.

[0082] Chemical reaction sufficiency mechanism: When the hot pressing time is 5 - 10 minutes, the dynamic crosslinking reaction and the formation of silicon-oxygen bonds can proceed fully, making the formation of chemical bonds in the dynamic reaction adhesion promotion layer reach the maximum, thus providing the highest adhesion strength.

[0083] Preferably, the tension control range during winding in S6 is 5 - 15 N, and the winding speed is 100 - 150 m / min.

[0084] Tension control range: 5 - 15 N;

[0085] Tension control is a key technical parameter in the winding process. The tension needs to be precisely maintained within the range of 5 - 15 N to balance the mechanical properties of the film material and the tightness of winding.

[0086] Mechanism of uniform tension distribution: Tension control can ensure the consistency of film material stretching in the entire width direction, avoiding film material skew or uneven winding caused by local tension differences.

[0087] Winding speed: 100 - 150 m / min;

[0088] The preferred range of the winding speed is 100 - 150 m / min. This range can match the production speeds of front-end extrusion coextrusion and hot pressing curing, while avoiding process problems caused by too high or too low speeds.

[0089] Mechanism of matching with the production rhythm: After hot pressing curing, the composite film is still in a certain thermoplastic state. A moderate winding speed can enable the composite film to enter the winding process after curing and cooling, avoiding local thermal deformation of the film material caused by too fast a speed.

[0090] Preferably, in the dynamic reaction adhesion promoting layer, the nano-graphene oxide introduces carboxyl or hydroxyl groups through acidification treatment, and the functionalized silica is modified with a silane coupling agent and has hydroxyl or amine groups.

[0091] Acidification treatment of nano-graphene oxide (fGO) Nano-graphene oxide is oxidized with strong acids (nitric acid, sulfuric acid or their mixed acid) to generate a large number of carboxyl (-COOH) or hydroxyl (-OH) groups. The specific method is as follows:

[0092] Disperse graphene oxide in concentrated nitric acid or sulfuric acid and stir for several hours;

[0093] Remove the residual acid through multiple water washings and filtrations to obtain graphene oxide modified with carboxyl or hydroxyl groups.

[0094] Mechanism of surface polarization:

[0095] Through acidification treatment, polar functional groups such as carboxyl (-COOH) and hydroxyl (-OH) are introduced onto the carbon skeleton surface of graphene oxide. These polar groups can form hydrogen bonds or covalent bonds with the polar groups (carbonyl, hydroxyl) on the molecular chains of polyurethane (PU) or polyvinyl alcohol (PVA) in the dynamic reaction adhesion promoting layer, thereby enhancing the interfacial chemical bonding force.

[0096] Enhanced dispersion:

[0097] The introduction of carboxyl and hydroxyl groups improves the dispersion of graphene oxide in the coating solution, avoids its agglomeration in the coating layer, and ensures that the nanomaterials can be evenly distributed in the coating layer, thus playing an enhancing role.

[0098] Mechanical anchoring:

[0099] The functionalized graphene oxide forms a microscopic embedding structure in the coating layer, and improves the anti-peeling ability and interfacial adhesion strength of the coating layer through mechanical anchoring.

[0100] Silane coupling agent modification of functionalized silica (fSiO2) Functionalized silica is surface-modified by a silane coupling agent (γ-aminopropyltriethoxysilane or γ-aminopropyltrimethoxysilane) to make its surface carry hydroxyl groups (-OH) or amine groups (-NH2). The specific method is as follows:

[0101] Add nano-silica into an organic solvent (ethanol or methanol) containing a silane coupling agent;

[0102] Heat and stir the reaction for several hours under neutral or weak alkaline conditions, then filter and dry to obtain the surface-modified functionalized silica.

[0103] Mechanism of enhanced chemical bonding:

[0104] The alkoxy (ethoxy) part of the silane coupling agent undergoes a condensation reaction with the silanol groups (Si-OH) on the surface of silica to form stable Si-O-Si bonds. At the same time, the other end (amine group or hydroxyl group) of the silane coupling agent is retained and can chemically bond (hydrogen bond or covalent bond) with polyurethane or polyvinyl alcohol in the dynamic reaction adhesion promotion layer to further enhance the interfacial bonding force.

[0105] Interface bridging:

[0106] The bifunctional characteristic of the silane coupling agent (one end binds to silica and the other end binds to the polymer) forms a bridge structure between the nanoparticles and the polymer matrix, effectively improving the interfacial chemical bonding force and mechanical properties.

[0107] Preferably, both the main film substrate and the secondary film substrate are subjected to corona treatment. The corona treatment parameters of the main film substrate are power 40-80W, treatment time 30-90 seconds, distance between the electrode and the substrate surface 5-10mm, and gas flow rate 20-50sccm; the corona treatment parameters of the secondary film substrate are the same as those of the main film substrate.

[0108] Corona treatment of the main film substrate:

[0109] The main film substrate is usually made of polyethylene (PE) or polypropylene (PP). Due to their low surface energy (usually 20 - 30 dyn / cm), it is difficult to achieve good interfacial adhesion when directly coating or laminating. Therefore, it is necessary to introduce polar groups on its surface through corona treatment to increase the surface energy and enhance its bonding with the dynamic reaction adhesion promoting layer.

[0110] Surface polarity improvement:

[0111] Corona treatment breaks the molecular chains on the substrate surface through high - voltage electric field discharge, generating free radicals. These free radicals are further oxidized in an oxygen or air environment to form polar groups (hydroxyl - OH, carboxyl - COOH, peroxy - C - O - OH). These polar groups interact with polar components (polyurethane, polyvinyl alcohol) in the dynamic reaction adhesion promoting layer through hydrogen bonds or chemical bonds, thus improving the adhesion.

[0112] Surface roughening:

[0113] During the corona discharge process, the substrate surface is bombarded by high - energy ions, forming a microscopic uneven structure. This surface roughening not only increases the physical contact area between the dynamic reaction adhesion promoting layer and the substrate, but also further enhances the interfacial bonding strength through mechanical interlocking.

[0114] Corona treatment of the secondary film substrate:

[0115] The secondary film substrate is also made of polyethylene (PE) or polypropylene (PP), and the process and parameters of its surface treatment are the same as those of the main film substrate. After corona treatment, the interfacial adhesion of the secondary film substrate with the dynamic reaction adhesion promoting layer is enhanced, and at the same time, the problem of delamination or peeling of the multi - layer composite film during subsequent use is avoided.

[0116] A laminating composite device based on the above cross-composite film production process, comprising a first reverse unwinding mechanism and a composite mechanism. The right side of the first reverse unwinding mechanism is equipped with a feeding mechanism, and the top of the feeding mechanism is installed with a first corona machine. The top of the first corona machine is connected to a printing and drying device. The top of the composite mechanism is installed with a single-screw extruder. The right side of the composite mechanism is connected to a second reverse unwinding mechanism. A second corona machine is installed between the composite mechanism and the second reverse unwinding mechanism. The right side of the second reverse unwinding mechanism is connected to a film slitting and powder spraying mechanism, and the right side of the film slitting and powder spraying mechanism is connected to a third reverse winding mechanism. The first reverse unwinding mechanism of the device is used to release the main film substrate. The reverse unwinding design ensures the tension stability of the film material during the unwinding process, avoiding coil relaxation or uneven tension. The feeding mechanism on the right side cooperates with it to achieve the stable transmission of the film material and provide a stable input substrate for subsequent processing. The tension control during unwinding and feeding is completed by precise sensors and tension adjustment devices. The first corona machine is installed on the top of the feeding mechanism, mainly used for surface pretreatment of the main film substrate to increase its surface polarity and surface energy. After corona treatment, the printing and drying device prints functional patterns on the substrate surface and dries it quickly. The power, gas flow rate, and treatment time of corona treatment are precisely adjusted by an automatic control system to meet the treatment requirements of different substrates. The composite mechanism is the core device of the equipment and is used in conjunction with a single-screw extruder. The single-screw extruder adheres and promotes the layer through high-temperature melting and dynamic reaction, uniformly coats it on the surface of the main film substrate, and simultaneously completes the extrusion coextrusion composite with the secondary film substrate. The composite mechanism is equipped with precise temperature, pressure, and thickness control systems to ensure the thickness uniformity and interfacial bonding strength of the multi-layer composite film. A second reverse unwinding mechanism is installed on the right side of the composite mechanism, used to release the secondary film substrate. The secondary film substrate is subjected to surface pretreatment through the second corona machine and then enters the composite area to complete the coextrusion composite with the main film substrate. The design of the second corona machine is similar to that of the first corona machine, but the treatment parameters are optimized for the secondary film substrate to meet the surface treatment requirements of different materials. The composite film enters the film slitting and powder spraying mechanism, which is used to spray specific functional powders, anti-sticking powders, or surface enhancers on the film surface, and at the same time cut off the excess edges of the film material to ensure the consistency of the final film width. The powder spraying mechanism uses precise nozzles to ensure uniform coverage of the powder. The third reverse winding mechanism is installed at the end of the device, used to wind the composite film material into a coil. The winding mechanism is equipped with a precise tension control system, and both the winding tension and speed can be adjusted to ensure the flatness and uniformity of the film material during the winding process.

[0117] The present invention provides a laminating composite device and a cross-composite film production process. It has the following beneficial effects:

[0118] 1. By adopting the technical solution of corona treatment for both the main film substrate and the secondary film substrate, the present invention introduces polar groups such as carboxyl and hydroxyl groups on the substrate surface, significantly improving the interfacial adhesion performance and achieving the effect of high peel strength of the multi-layer composite film. Compared with the prior art solutions that treat only one-sided substrate, it overcomes the problems of insufficient interfacial bonding strength and easy delamination of multi-layer films in high-humidity and high-temperature environments.

[0119] 2. By adding acid-treated nano-graphene oxide and functionalized silica modified by silane coupling agent to the dynamic reaction adhesion promoting layer, the present invention enables the adhesion promoting layer to have stronger chemical bonding ability and mechanical anchoring effect, achieving the effect of improving adhesion and overall mechanical properties. Compared with the prior art solutions that directly use untreated nano-materials, it solves the problem of uneven coating layer performance caused by nano-material agglomeration.

[0120] 3. By adopting the dynamic cross-linking chemistry technology and using dihydroxybenzene and silane coupling agent in the dynamic reaction adhesion promoting layer, a stable three-dimensional cross-linking network is formed during the hot pressing and curing process, enhancing the interfacial bonding stability of the composite film. Compared with the traditional static adhesion layer, it solves the deficiency of the decrease in interfacial adhesion force of the composite film under stress, and significantly improves the durability of the composite film in high-load usage scenarios.

[0121] 4. By optimizing the extrusion co-extrusion and winding process parameters, the present invention ensures good uniformity and stability during the interfacial bonding process of the main substrate, the dynamic reaction adhesion promoting layer, and the secondary substrate. Especially through the precise control of tension and speed, it achieves the effect of uniform composite film thickness and defect-free interface. Compared with the problem of uneven winding caused by tension fluctuation in the prior art, it improves the applicability of the composite film in subsequent processing. BRIEF DESCRIPTION OF THE DRAWINGS

[0122] Figure 1 is a schematic structural diagram of the film laminating composite equipment of the present invention;

[0123] Figure 2 is a schematic process flow diagram of the production of the cross composite film of the present invention.

[0124] Among them, 1. Single-extrusion extruder; 2. First reverse unwinding mechanism; 3. Feeding mechanism; 4. Printing and drying device; 5. Composite mechanism; 6. Second reverse unwinding mechanism; 7. Film chopping and powder spraying mechanism; 8. Third reverse winding mechanism; 9. First corona machine; 10. Second corona machine. DETAILED DESCRIPTION OF THE INVENTION

[0125] The technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0126] Embodiment 1:

[0127] Corona treatment of the main film substrate:

[0128] Take a polypropylene film (with a thickness of 50 μm) and place it in a corona treatment device. Adjust the device power to 50 W, the gas flow rate to 30 sccm, the distance between the electrode and the film surface to 7 mm, and the treatment time to 60 seconds. After treatment, the surface energy of the film is increased from the original 28 dyn / cm to 46 dyn / cm.

[0129] Corona treatment of the secondary film substrate:

[0130] Use a polyethylene film (with a thickness of 40 μm) and perform corona treatment in the same way. Set the power to 60 W, the gas flow rate to 45 sccm, the electrode distance to 8 mm, and the treatment time to 90 seconds. After treatment, the surface energy is increased to 48 dyn / cm, and a uniform concave-convex distribution is observed in the surface microstructure.

[0131] Coating of the dynamic reaction adhesion promoting layer:

[0132] Prepare the coating solution: Dissolve 65 parts of polyurethane (PU) in a mixed solvent of ethanol / water (1:1), and stir until completely dissolved. Add 5 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, 4 parts of nano-graphene oxide (treated with nitric acid), and 6 parts of functionalized silica (modified with a silane coupling agent). Continue to stir at 800 rpm for 40 minutes to obtain a uniform dispersion. Use a doctor blade coating process to coat the coating solution on the surface of the main film substrate, and the coating amount is 0.3 g / m 2 , and the coating thickness is 1.2 μm. Subsequently, dry it at 80 °C for 4 minutes.

[0133] Extrusion coextrusion:

[0134] In the extrusion equipment, set the temperature of the main substrate to 200 °C, the dynamic reaction adhesion promoting layer to 170 °C, and the secondary substrate to 200 °C. Control the extrusion speed at 120 m / min and adjust the pressure to 25 MPa. Complete the lamination through a multi-layer coextrusion die head.

[0135] Hot pressing and curing:

[0136] Feed the composite film into a hot press, set the temperature to 140 °C, adjust the pressure to 15 MPa, and keep for 6 minutes. After completion, cool to room temperature.

[0137] Rewinding:

[0138] The composite film passes through a tension control device, the tension is set to 10 N, and the rewinding speed is 130 m / min. The rewinding is completed.

[0139] Example 2:

[0140] Corona treatment of the main film substrate:

[0141] Select a polyethylene film (thickness 45 μm), set the power to 40 W, gas flow rate 20 sccm, electrode distance 6 mm, and treatment time 40 seconds. After treatment, fine oxidation products appear on the surface.

[0142] Corona treatment of the secondary film substrate:

[0143] Use a polypropylene film (thickness 35 μm), adjust the power to 70 W, gas flow rate 40 sccm, electrode distance 9 mm, and treatment time 70 seconds. The surface roughening effect is significant.

[0144] Coating of the dynamic reaction adhesion promoting layer:

[0145] Prepare the coating solution: Dissolve 70 parts of polyvinyl alcohol (PVA) in water at 70 °C and stir until a transparent solution is obtained. Add 4 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, 5 parts of nano-graphene oxide (treated with nitric acid), and 7 parts of functionalized silica (modified with γ-aminopropyltriethoxysilane). Continue stirring at 700 rpm for 50 minutes. Using the casting process, uniformly spread the coating solution onto the surface of the main film substrate, and the coating amount is 0.4 g / m 2 , and the coating thickness is 1.0 μm. Set the drying temperature to 90 °C and the time to 5 minutes.

[0146] Extrusion coextrusion:

[0147] The main film substrate, the dynamic reaction adhesion promoting layer, and the secondary film substrate enter the coextrusion die head synchronously. The temperature of the main substrate is 195 °C, the dynamic reaction layer is 180 °C, and the secondary substrate is 190 °C. The extrusion speed is 150 m / min, and the pressure is set to 30 MPa.

[0148] Hot pressing and curing:

[0149] Set the temperature of the hot press to 130 °C, adjust the pressure to 12 MPa, and the curing time is 8 minutes. Then, slowly cool to room temperature.

[0150] Rewinding:

[0151] The winding tension is set at 8 N and the speed is controlled at 140 m / min. After winding, check and there is no warping or wrinkling.

[0152] Example 3:

[0153] Corona treatment of the main film substrate:

[0154] Take a polypropylene film (thickness 60 μm), with a corona treatment power of 50 W, a gas flow rate of 35 sccm, a distance between the electrode and the substrate of 7 mm, and a treatment time of 60 seconds. The measured surface energy is increased from 30 dyn / cm to 45 dyn / cm.

[0155] Corona treatment of the secondary film substrate:

[0156] A polyethylene film (thickness 55 μm) is treated under the conditions of a power of 60 W, a gas flow rate of 50 sccm, a distance of 8 mm, and a treatment time of 90 seconds. After treatment, the surface roughening effect is significant.

[0157] Coating of the dynamic reaction adhesion promoting layer:

[0158] Dissolve 60 parts of polyurethane in ethanol / water (1:1), add 6 parts of γ-aminopropyltriethoxysilane, 4 parts of dihydroxybenzene, 5 parts of acid-treated nano-graphene oxide, and 6 parts of functionalized silica modified with a silane coupling agent. Stir at 800 rpm for 40 minutes to prepare a uniform coating solution. Coat by a doctor blade process, with a coating amount of 0.35 g / m 2 , a thickness of 1.2 μm, and drying conditions of 80 °C for 4 minutes.

[0159] Extrusion coextrusion:

[0160] The extrusion temperature is 205 °C for the main substrate, 175 °C for the dynamic reaction adhesion promoting layer, 200 °C for the secondary substrate, the speed is 125 m / min, and the pressure is 25 MPa.

[0161] Hot pressing and curing:

[0162] The hot pressing temperature is 140 °C, the pressure is 16 MPa, and the curing time is 5 minutes. After cooling, the treatment is completed.

[0163] Winding:

[0164] The tension is 12 N, the speed is 130 m / min, and there are no obvious defects on the film roll after winding.

[0165] Comparative Example 1: The main film substrate is not subjected to corona treatment:

[0166] Based on the preparation process of Example 1, the corona treatment step of the main film substrate is not carried out, and the other steps remain the same:

[0167] The main film substrate is a polypropylene film (thickness 50μm) without corona treatment, and the dynamic reaction adhesion promoting layer is directly coated.

[0168] The process parameters of the dynamic reaction adhesion promoting layer, such as formulation, coating, extrusion coextrusion, hot pressing and curing, winding, etc. are all the same as those in Example 1.

[0169] Comparative Example 2: The secondary film substrate is not corona treated:

[0170] Based on the preparation process of Example 1, the corona treatment step of the secondary film substrate is not processed, and the remaining steps remain the same:

[0171] The main film substrate is still corona treated, with parameters of power 50W, gas flow rate 30sccm, electrode distance 7mm, and treatment time 60 seconds.

[0172] The secondary film substrate is a polyethylene film (thickness 40μm) without corona treatment.

[0173] The preparation of the dynamic reaction adhesion promoting layer and the subsequent process flow are the same as those in Example 1.

[0174] Comparative Example 3: Functionalized nano-graphene oxide and functionalized silica are not used in the dynamic reaction adhesion promoting layer:

[0175] Based on the preparation process of Example 1, nano-graphene oxide and functionalized silica are removed from the formulation of the dynamic reaction adhesion promoting layer, and the remaining components and processes remain the same:

[0176] The formulation of the dynamic reaction adhesion promoting layer is changed to: 65 parts of polyurethane (PU), 5 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, ethanol / water mixed solvent (1:1).

[0177] The process parameters of coating, extrusion coextrusion, hot pressing and curing, winding are the same as those in Example 1.

[0178] Comparative Example 4: The nanomaterials in the dynamic reaction adhesion promoting layer are not functionalized:

[0179] Based on the preparation process of Example 1, unfunctionalized nano-graphene oxide and silica are used in the dynamic reaction adhesion promoting layer, and the remaining steps remain the same:

[0180] The formulation of the dynamic reaction adhesion promoting layer is changed to: 65 parts of polyurethane (PU), 5 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, 4 parts of non-acidified nano-graphene oxide, 6 parts of silica unmodified by silane coupling agent.

[0181] The process parameters of coating, extrusion coextrusion, hot pressing and curing, winding are the same as those in Example 1.

[0182] Comparative Example 5: Adjustment of the key component ratio in the dynamic reaction adhesion promoting layer:

[0183] Based on the preparation process of Example 1, the component ratio of the dynamic reaction adhesion promoting layer was adjusted, and other processes remained the same:

[0184] The dosage of γ-aminopropyltriethoxysilane was reduced to 2 parts, and the dosage of dihydroxybenzene was reduced to 1 part.

[0185] The dosage of nano-graphene oxide was increased to 8 parts, and the functionalized silica was reduced to 3 parts.

[0186] The process parameters of coating, co-extrusion by extrusion, hot pressing and curing, and winding were the same as those in Example 1.

[0187] Comparative Example 6: Change in hot pressing and curing parameters:

[0188] Based on the preparation process of Example 1, the parameters of hot pressing and curing were adjusted, and the rest of the process remained the same:

[0189] The hot pressing temperature was adjusted to 110 °C, the pressure was 8 MPa, and the time was 3 minutes.

[0190] The remaining processes, including the corona treatment of the main film substrate and the secondary film substrate, the coating of the dynamic reaction adhesion promoting layer, and the co-extrusion process by extrusion, were the same as those in Example 1.

[0191] Comparative Example 7: The winding tension and speed are not within the preferred range:

[0192] Based on the preparation process of Example 1, the tension and speed of the winding process were adjusted, and the rest of the process remained the same:

[0193] The winding tension was adjusted to 3 N, and the winding speed was adjusted to 180 m / min.

[0194] The corona treatment of the main film substrate and the secondary film substrate, the coating of the dynamic reaction adhesion promoting layer, the co-extrusion process by extrusion, and the hot pressing and curing process were the same as those in Example 1.

[0195] Comparative Example 8: No corona treatment was carried out and the dynamic reaction adhesion promoting layer does not contain functionalized nanomaterials:

[0196] Based on the preparation process of Example 1, the adjustments of Comparative Example 1 and Comparative Example 3 were combined:

[0197] Neither the main film substrate nor the secondary film substrate was subjected to corona treatment.

[0198] The nano-graphene oxide and functionalized silica were removed from the formulation of the dynamic reaction adhesion promoting layer.

[0199] The remaining processes of coating, co-extrusion by extrusion, hot pressing and curing, and winding were the same as those in Example 1.

[0200] Experiment 1: Verify the effect of corona treatment on interfacial adhesion; Experiment purpose: By comparing the corona treatment of the main film substrate and the secondary film substrate, verify the role of corona treatment in improving interfacial adhesion performance.

[0201] Experimental materials and equipment: Materials: Polypropylene film (main film substrate, thickness 50μm); polyethylene film (secondary film substrate, thickness 40μm); dynamic reaction adhesion promoting coating liquid (formulation of Example 1).

[0202] Equipment: Corona treatment device, scraping coating equipment, multi-layer co-extrusion equipment, hot press, tensile testing machine.

[0203] Experimental procedure:

[0204] Substrate treatment:

[0205] Example 1: Both the main film substrate and the secondary film substrate are subjected to corona treatment. The corona parameters for the main film are power 50W, gas flow rate 30 sccm, electrode distance 7mm, and treatment time 60 seconds; the corona parameters for the secondary film are power 60W, gas flow rate 45 sccm, electrode distance 8mm, and treatment time 90 seconds.

[0206] Comparative example 1: The main film is not subjected to corona treatment, and the remaining operations are the same as in Example 1.

[0207] Comparative example 2: The secondary film is not subjected to corona treatment, and the remaining operations are the same as in Example 1.

[0208] Coating of dynamic reaction adhesion promoting layer:

[0209] The coating liquid is prepared according to the formulation of Example 1. Through the scraping coating process, the coating liquid is evenly coated on the surface of the main film substrate, and the coating amount is 0.3 g / m 2 , and the coating thickness is 1.2μm.

[0210] After coating, it is dried at 80°C for 4 minutes.

[0211] Extrusion co-extrusion:

[0212] It is carried out according to the extrusion parameters of Example 1. The temperature of the main film substrate is 200°C, the dynamic reaction adhesion promoting layer is 170°C, the secondary film substrate is 200°C, the extrusion speed is 120 m / min, and the pressure is 25 MPa.

[0213] Hot press curing:

[0214] The temperature of the hot press is 140°C, the pressure is 15 MPa, and the time is 6 minutes. After completion, it is cooled to room temperature.

[0215] Peel strength test:

[0216] Prepare a composite film strip with a width of 15 mm according to ASTM D1876 standard. Use a tensile testing machine to test the maximum force value (N / 15 mm) required for peeling at a speed of 100 mm / min.

[0217] Data recording:

[0218] Each group of samples is tested 5 times, and the average peeling strength is calculated.

[0219] Experimental data:

[0220] Table 1: Influence of different treatment methods on the peeling strength of the composite film:

[0221] Sample Number Treatment Method Peel Strength (N / 15mm) Example 1-1 Both the main film substrate and the secondary film substrate are corona-treated 8.5 Example 1-2 Both the main film substrate and the secondary film substrate are corona-treated 8.2 Example 1-3 Both the main film substrate and the secondary film substrate are corona-treated 8.4 Example 1-4 Both the main film substrate and the secondary film substrate are corona-treated 8.7 Example 1-5 Both the main film substrate and the secondary film substrate are corona-treated 8.6 Comparative Example 1-1 The main film substrate is not corona-treated, and the secondary film substrate is corona-treated 4.1 Comparative Example 1-2 The main film substrate is not corona-treated, and the secondary film substrate is corona-treated 3.9 Comparative Example 1-3 The main film substrate is not corona-treated, and the secondary film substrate is corona-treated 4.3 Comparative Example 1-4 The main film substrate is not corona-treated, and the secondary film substrate is corona-treated 4 Comparative Example 1-5 The main film substrate is not corona-treated, and the secondary film substrate is corona-treated 4.2 Comparative Example 2-1 The main film substrate is corona-treated, and the secondary film substrate is not corona-treated 5.1 Comparative Example 2-2 The main film substrate is corona-treated, and the secondary film substrate is not corona-treated 5.4 Comparative Example 2-3 The main film substrate is corona-treated, and the secondary film substrate is not corona-treated 5.3 Comparative Example 2-4 The main film substrate is corona-treated, and the secondary film substrate is not corona-treated 5.2 Comparative Example 2-5 The main film substrate is corona-treated, and the secondary film substrate is not corona-treated 5.5

[0222] Corona treatment significantly improves the surface polarity and roughness of the main film and sub-film substrates, and promotes the chemical and physical bonding between the dynamic reaction adhesion promoting layer and the substrates. Bilateral corona treatment (Example 1) shows higher interfacial bonding strength, while untreated substrates (Comparative Examples 1 and 2) result in a significant decrease in peeling strength. This proves the key role of corona treatment in improving interfacial adhesion performance.

[0223] Experiment 2: Verify the influence of functionalized nanomaterials on the properties of the coating layer:

[0224] Experimental purpose:

[0225] Explore the influence of the functionalization treatment of nano-graphene oxide and functionalized silica in the dynamic reaction adhesion promoting layer on the dispersibility of the coating layer and the interfacial adhesion performance of the composite film.

[0226] Experimental materials and equipment:

[0227] Materials:

[0228] Nano-graphene oxide (acid-treated and untreated); functionalized silica (silane-modified and unmodified); polyurethane (PU); γ-aminopropyltriethoxysilane; dihydroxybenzene; ethanol / water mixed solvent (1:1).

[0229] Polypropylene film (thickness 50 μm, main film substrate); polyethylene film (thickness 40 μm, sub-film substrate).

[0230] Equipment: Scanning electron microscope (SEM), scraping equipment, hot press, tensile testing machine.

[0231] Experimental procedure:

[0232] Preparation of coating solution: Example

[0233] When preparing the coating solution, 65 parts of polyurethane (PU) are dissolved in ethanol / water (1:1), and 5 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, 4 parts of acid-treated nano-graphene oxide, and 6 parts of silane-modified functionalized silica are added. Stir at 800 rpm for 40 minutes until uniformly dispersed.

[0234] Comparative Example 3:

[0235] In the formulation, nano-graphene oxide and functionalized silica are not added, and the other components and stirring conditions remain the same.

[0236] Comparative Example 4:

[0237] In the formulation, non-functionalized nano-graphene oxide and unmodified silica by silane are used, and the other formulations and stirring conditions remain the same.

[0238] Coating and drying:

[0239] Using the knife coating process, the coating solution is coated on the surface of the main film substrate, with a coating amount of 0.3 g / m 2 , and the coating thickness is 1.2 μm. Subsequently, it is dried at 80 °C for 4 minutes.

[0240] Composite film preparation:

[0241] The same extrusion coextrusion and hot pressing curing process as in Example 1 is adopted (extrusion temperature: main film 200 °C, secondary film 200 °C, dynamic reaction adhesion layer 170 °C, extrusion speed 120 m / min, pressure 25 MPa; hot pressing temperature 140 °C, pressure 15 MPa, time 6 minutes).

[0242] Testing and characterization:

[0243] Use a scanning electron microscope (SEM) to observe the distribution of nanoparticles in the coating layer, focusing on whether the distribution is uniform and whether there is agglomeration.

[0244] Use the ASTM D1876 standard peel strength test to evaluate the interfacial adhesion performance (same method as in Experiment 1).

[0245] Experimental data:

[0246] Table 2: Influence of functionalized nano-materials on the distribution and peel strength of the coating layer:

[0247] Sample Number Functionalization Status of Nanomaterials SEM Observation (Distribution Characteristics) Peel Strength (N / 15mm) Example 1-1 Functionalization Treatment (Acidification, Silane Modification) Uniform Distribution, No Obvious Agglomeration 8.4 Example 1-2 Functionalization Treatment (Acidification, Silane Modification) Basically Uniform, Occasional Small Agglomerations 8.5 Comparative Example 3-1 Without Nanomaterials No Nanoparticle Distribution 4.2 Comparative Example 3-2 Without Nanomaterials No Nanoparticle Distribution 4.1 Comparative Example 4-1 Not Functionally Treated Severe Agglomeration, Uneven Distribution 5.6 Comparative Example 4-2 Not Functionally Treated Large-Area Agglomeration 5.4

[0248] Functionalized nano-graphene oxide and functionalized silica significantly improve the dispersibility and interfacial bonding strength of the coating layer. In the sample of Example 1, the nano-materials are evenly distributed and the peel strength is the highest; in Comparative Examples 3 and 4, the unadded or unfunctionalized nano-materials lead to a significant decrease in the peel strength and coating layer performance due to particle agglomeration or lack of enhancement. The functionalization treatment is the core technology to improve the performance of the dynamic reaction adhesion layer.

[0249] Experiment 3: Verify the influence of the component ratio of the coating solution on the adhesion performance:

[0250] Experiment purpose:

[0251] Explore the influence of the key component ratio in the dynamic reaction adhesion promotion layer on the interfacial adhesion performance and the mechanical properties of the coating layer.

[0252] Experiment materials and equipment:

[0253] Materials:

[0254] Polyurethane (PU); γ-aminopropyltriethoxysilane; dihydroxybenzene; nano-graphene oxide (acid-treated); functionalized silica (silanized).

[0255] Polypropylene film (thickness 50μm, main film substrate); polyethylene film (thickness 40μm, secondary film substrate).

[0256] Equipment: Dynamic mechanical analyzer (DMA), tensile testing machine.

[0257] Experiment process:

[0258] Coating solution preparation: Example

[0259] The formula is 65 parts of polyurethane (PU), 5 parts of γ-aminopropyltriethoxysilane, 3 parts of dihydroxybenzene, 4 parts of acid-treated nano-graphene oxide, and 6 parts of functionalized silica. Add each component to the ethanol / water mixed solvent (1:1), stir at 800 rpm for 40 minutes until completely dispersed.

[0260] Comparative Example 5:

[0261] Adjust the formula ratio to 65 parts of PU, 2 parts of γ-aminopropyltriethoxysilane, 1 part of dihydroxybenzene, 8 parts of nano-graphene oxide, and 3 parts of functionalized silica. The remaining steps are the same as those in Example 1.

[0262] Coating and drying:

[0263] Use the doctor blade coating process to evenly coat the coating solution on the surface of the main film substrate, with a coating amount of 0.3 g / m 2 , and the coating thickness is 1.2μm. The drying temperature is 80°C and the time is 4 minutes.

[0264] Preparation of composite film:

[0265] The main film substrate, coating layer, and secondary film substrate enter the extrusion co-extrusion equipment simultaneously. The temperature of the main film substrate is 200°C, the secondary film substrate is 200°C, the dynamic reaction adhesion promotion layer is 170°C, the extrusion speed is 120 m / min, and the pressure is 25 MPa. The composite film is prepared by hot pressing and curing (temperature 140°C, pressure 15 MPa, time 6 minutes).

[0266] Performance testing:

[0267] Peel strength test (ASTM D1876): Using the same method as in Experiment 1, test the peel strength of the composite film and record the maximum force value.

[0268] Dynamic mechanical analysis (DMA): Test the storage modulus (E’) of the coating layer on the DMA equipment to evaluate the elasticity and mechanical stability of the coating layer.

[0269] Experimental data:

[0270] Table 3: Influence of the component ratio of the dynamic reaction adhesion promotion layer on the adhesion performance and storage modulus:

[0271] Sample Number Component Ratio (Adjustment of Key Components) Peel Strength (N / 15mm) Storage Modulus E' (MPa) Example 1-1 5 parts of γ-silane, 3 parts of dihydroxybenzene, 4 parts of GO, 6 parts of SiO2 8.4 152 Example 1-2 5 parts of γ-silane, 3 parts of dihydroxybenzene, 4 parts of GO, 6 parts of SiO2 8.6 154 Comparative Example 5-1 2 parts of γ-silane, 1 part of dihydroxybenzene, 8 parts of GO, 3 parts of SiO2 6.1 96 Comparative Example 5-2 2 parts of γ-silane, 1 part of dihydroxybenzene, 8 parts of GO, 3 parts of SiO2 5.8 101

[0272] Optimization of the ratio of key components (γ-silane and dihydroxybenzene) is the key to improving the interfacial adhesion strength. The formulation in Example 1 provides the best chemical bonding force and dynamic crosslinking performance, while the decrease in the ratio of key components in Comparative Example 5 leads to a significant decrease in peel strength and storage modulus. Rational adjustment of the component ratio is the basis for optimizing the adhesion performance.

[0273] Experiment 4: Verify the influence of hot pressing and curing parameters on the interfacial chemical reaction:

[0274] Experimental purpose:

[0275] Study the influence of the temperature, pressure, and time of hot pressing and curing on the sufficiency of the interfacial chemical reaction and the adhesion performance of the composite film, and explore the key role of the hot pressing process on the dynamic reaction adhesion promotion layer.

[0276] Experimental materials and equipment:

[0277] Materials:

[0278] The main film substrate (polypropylene, thickness 50 μm) coated with the dynamic reaction adhesion promotion layer, and the secondary film substrate (polyethylene, thickness 40 μm).

[0279] Equipment: Hot press, Fourier transform infrared spectrometer (FTIR), tensile testing machine.

[0280] Experimental procedure:

[0281] Preparation of composite film:

[0282] Example 1: After the main film substrate and the secondary film substrate are corona-treated, a composite film is prepared according to the process of Example 1 (including coating solution preparation, coating, and drying).

[0283] Comparative Example 6: The preparation process is the same as that of Example 1, only the hot pressing process parameters are adjusted to: temperature 110°C, pressure 8 MPa, and time 3 minutes.

[0284] Hot pressing and curing:

[0285] Example 1: The hot pressing temperature is set at 140°C, the pressure is 15 MPa, and the time is 6 minutes.

[0286] Comparative Example 6: The hot pressing temperature is reduced to 110°C, the pressure is 8 MPa, and the time is 3 minutes. The other conditions remain the same.

[0287] Interface reaction test (FTIR):

[0288] Use FTIR to detect the interfacial chemical reaction of the composite film, and focus on observing the characteristic absorption peaks of the silicon-oxygen bond (Si-O-Si) and the dynamic crosslinking network (the absorption peak of the C=C bond weakens and the formation peak of the Si-O bond strengthens).

[0289] Peel strength test:

[0290] Use the ASTM D1876 standard to test the peel strength of the composite film, and record the maximum force value (N / 15 mm).

[0291] Experimental data:

[0292] Table 4: Influence of hot pressing parameters on the interfacial chemical reaction and peel strength of the composite film:

[0293] Sample Number Hot Pressing Parameters Change of FTIR Characteristic Peaks Peel Strength (N / 15mm) Example 1-1 140°C, 15 MPa, 6 minutes Si-O-Si peak is significant, C=C peak weakens 8.5 Example 1-2 140°C, 15 MPa, 6 minutes Interface reaction is sufficient, crosslinking peak enhances 8.7 Comparative Example 6-1 110°C, 8 MPa, 3 minutes Si-O-Si peak is weak, C=C peak remains obvious 4.6 Comparative Example 6-2 110°C, 8 MPa, 3 minutes Interface reaction is incomplete, dynamic crosslinking peak is not significant 4.8

[0294] The hot pressing temperature and pressure directly affect the sufficiency of the interfacial chemical reaction. In Example 1, under the optimized hot pressing parameters, the silicon-oxygen bond and the dynamic crosslinking network are fully formed, and the peel strength is the highest; while in Comparative Example 6, the reaction is incomplete, resulting in a decrease in the interfacial bonding force. Appropriate hot pressing conditions are crucial for activating the interfacial chemical reaction and improving the adhesion of the composite film.

[0295] Experiment 5: Verify the influence of winding parameters on the uniformity and mechanical properties of the composite film:

[0296] Experimental purpose:

[0297] Analyze the influence of different winding tensions and speeds on the surface uniformity and overall mechanical properties of the composite film, and explore the role of the tension and speed matching on the final quality of the multi-layer composite film.

[0298] Experimental materials and equipment:

[0299] Materials: The composite film prepared in Example 1.

[0300] Equipment: Rewinder, optical microscope (OM), tensile testing machine.

[0301] Experimental procedure:

[0302] Settings of rewinding parameters:

[0303] Example 1: The rewinding tension is set to 10 N and the speed is 130 m / min.

[0304] Comparative Example 7: The rewinding tension is adjusted to 3 N and the rewinding speed is increased to 180 m / min, and the remaining steps are the same as those in Example 1.

[0305] Sample preparation:

[0306] After coating, extrusion coextrusion and hot pressing curing are completed according to Example 1, the composite film is divided into two groups and different rewinding processes are carried out respectively.

[0307] Surface uniformity test:

[0308] Use an optical microscope to observe the surface of the rewound composite film sample, and record the wrinkles, creases or locally uneven areas on the film surface. Random position photos of 3 samples are collected for comparative analysis.

[0309] Mechanical property test:

[0310] Test the tensile strength of the composite film according to ASTM D882:

[0311] Prepare a test specimen with a width of 10 mm and a length of 100 mm, and clamp it on the tensile testing machine;

[0312] Stretch it to break at a speed of 50 mm / min, and record the maximum breaking strength.

[0313] Experimental data:

[0314] Table 5: Effects of different rewinding parameters on the surface uniformity and mechanical properties of the composite film:

[0315] Sample Number Rewinding Parameters Surface Observation (Wrinkles / Non-uniformity) Tensile Strength (MPa) Example 1-1 Tension 10 N, Speed 130 m / min Surface is flat, with a small number of slight scratches 89 Example 1-2 Tension 10 N, Speed 130 m / min Flat, without obvious defects 92 Comparative Example 7-1 Tension 3 N, Speed 180 m / min Obvious wrinkles, more non-uniform areas 61 Comparative Example 7-2 Tension 3N, speed 180m / min Local wrinkling, edge damage 64

[0316] In Example 1, the reasonable matching of tension and speed ensured the flatness and high tensile strength of the composite film surface; while in Comparative Example 7, due to insufficient tension and too high speed, wrinkles appeared on the film material and the mechanical properties decreased. The optimization of the rewinding process is of great significance for maintaining the overall quality and interfacial bonding force of the composite film.

[0317] Experiment 6: Verify the synergistic effect of the dynamic reaction adhesion promoting layer and corona treatment:

[0318] Purpose of the experiment:

[0319] By comparing different combinations of corona treatment and dynamic reactive adhesion promotion layer, study the synergistic effect of the two on the interfacial adhesion performance and stability in humid and hot environment of the composite film.

[0320] Experimental materials and equipment:

[0321] Materials:

[0322] Dynamic reactive adhesion promotion layer (formulation of Example 1 and formulation without nanomaterials).

[0323] Main film substrate (polypropylene, thickness 50 μm); secondary film substrate (polyethylene, thickness 40 μm).

[0324] Equipment: Tensile testing machine, damp and heat test chamber.

[0325] Experimental procedure:

[0326] Sample preparation:

[0327] Example 1: Both the main film substrate and the secondary film substrate are subjected to corona treatment, and the formulation of the dynamic reactive adhesion promotion layer contains functionalized nanomaterials.

[0328] Comparative Example 8: Neither the main film substrate nor the secondary film substrate is subjected to corona treatment, and the dynamic reactive adhesion promotion layer does not contain nanomaterials.

[0329] Coating and lamination:

[0330] Coat the dynamic reactive adhesion promotion layer on the surface of the main film substrate, with a coating amount of 0.3 g / m 2 , and the coating thickness is 1.2 μm.

[0331] The main film substrate, the coating layer and the secondary film substrate enter the extrusion coextrusion equipment synchronously. The temperature of the main film substrate is 200 °C, the dynamic reaction layer is 170 °C, the secondary film substrate is 200 °C, the extrusion speed is 120 m / min, and the pressure is 25 MPa.

[0332] Thermal pressing and curing conditions: temperature 140 °C, pressure 15 MPa, time 6 minutes.

[0333] Peel strength test (ASTM D1876):

[0334] Prepare a composite film spline with a width of 15 mm, and use a tensile testing machine to test the peel strength at a speed of 100 mm / min.

[0335] Damp and heat aging test:

[0336] Place the sample in a damp heat test chamber, set the temperature to 60°C and the relative humidity to 95%, and place it for 72 hours. Retest the peel strength after aging to evaluate the performance retention rate.

[0337] Experimental data:

[0338] Table 6: Influence of the synergistic effect of corona treatment and dynamic reactive adhesion promoting layer on the properties of composite films:

[0339] Sample number Treatment method Initial peel strength (N / 15mm) Peel strength after damp heat (N / 15mm) Performance retention rate (%) Example 1-1 Corona + dynamic reaction layer (containing functionalized nanomaterials) 8.5 7.9 92 Example 1-2 Corona + dynamic reaction layer (containing functionalized nanomaterials) 8.7 8.1 93 Comparative example 8-1 No corona + no functionalized nanomaterials 3.5 1.8 51 Comparative example 8-2 No corona + no functionalized nanomaterials 3.6 1.9 53

[0340] The synergistic effect of corona treatment and dynamic reactive adhesion promoting layer significantly improves the interfacial adhesion performance and stability in a damp heat environment. The performance retention rate of the sample in Example 1 is as high as 92% after damp heat treatment. In Comparative Example 8, due to the lack of corona treatment and functionalized nanomaterials, the interfacial bonding strength and durability are significantly reduced. Synergistic optimization is the key to achieving high adhesion performance and environmental stability.

[0341] Although the embodiments of the present invention have been shown and described, it will be understood by those of ordinary skill in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A production process of a cross-composite film, characterized in that, It includes the following steps: S1. Perform surface pretreatment on the main film substrate; Both the main film substrate and the secondary film substrate are subjected to corona treatment. The corona treatment parameters for the main film substrate are: power 40 - 80 W, treatment time 30 - 90 seconds, distance between the electrode and the substrate surface 5 - 10 mm, and gas flow rate 20 - 50 sccm; the corona treatment parameters for the secondary film substrate are the same as those of the main film substrate; S2. Prepare the coating liquid for the dynamic reaction adhesion promoting layer; The method for preparing the coating liquid for the dynamic reaction adhesion promoting layer in S2 includes the following steps: Dissolve polyurethane or polyvinyl alcohol in an ethanol / water mixed solvent; Sequentially add γ-aminopropyltriethoxysilane, dihydroxybenzene, nano-graphene oxide, and functionalized silica; Stir at a stirring speed of 500 - 1000 rpm for 30 - 60 minutes to obtain a homogeneous dispersion; S3. Coat the dynamic reaction adhesion promoting layer onto the surface of the main film substrate; The nano-graphene oxide in the dynamic reaction adhesion promoting layer introduces carboxyl or hydroxyl groups through acidification treatment, and the functionalized silica has hydroxyl or amine groups after being modified by a silane coupling agent; S4. Multilayer composite the main film substrate, the dynamic reaction adhesion promoting layer, and the secondary film substrate through an extrusion coextrusion device; The parameters of the extrusion coextrusion process in S4 are: the extrusion temperature of the main substrate layer is 190 - 250 °C, the extrusion temperature of the interlayer is 150 - 200 °C, the extrusion temperature of the secondary substrate layer is 190 - 250 °C, the extrusion speed is 100 - 150 m / min, and the pressure is 20 - 50 MPa; S5. Perform hot pressing and curing treatment on the composite film; The parameters of hot pressing and curing in S5 are: hot pressing temperature 120 - 150 °C, pressure 10 - 20 MPa, and time 5 - 10 minutes; S6. Wind up to obtain the finished product; Among them, the main film substrate includes 80 - 95 parts by mass of polyethylene or polypropylene, 3 - 10 parts by mass of maleic anhydride grafted polymer, and 0.5 - 2 parts by mass of processing aids; The dynamic reaction adhesion promoting layer includes 60 - 80 parts by mass of polyurethane or polyvinyl alcohol, 3 - 8 parts by mass of γ-aminopropyltriethoxysilane, 2 - 5 parts by mass of dihydroxybenzene, 3 - 6 parts by mass of nano-graphene oxide, 4 - 8 parts by mass of functionalized silica, and 10 - 20 parts by mass of ethanol / water mixed solvent; The secondary film substrate includes 80 - 95 parts by mass of polyethylene or polypropylene, 3 - 10 parts by mass of maleic anhydride grafted polymer, and 0.5 - 2 parts by mass of processing aids.

2. The production process of a cross-composite film according to claim 1, characterized in that, The method for performing surface pretreatment on the main film substrate in S1 includes low-temperature plasma treatment, and the treatment parameters are: power 40 - 80 W, treatment time 30 - 90 seconds, distance from the electrode 5 - 10 mm, and gas flow rate 20 - 50 sccm.

3. The production process of a cross-composite film according to claim 1, characterized in that, The method for coating the dynamic reaction adhesion promoting layer in S3 is the doctor blade coating or casting process, and the coating amount is 0.1 - 0.5 g / m 2 , the coating thickness is 0.5 - 1.5 μm, the preliminary drying temperature is 70 - 100 °C, and the drying time is 3 - 5 minutes.

4. The production process of a cross-composite film according to claim 1, characterized in that, The tension control range for winding up in S6 is 5 - 15 N, and the winding up speed is 100 - 150 m / min.

5. A film laminating and compounding device based on the production process of the cross-composite film described in claim 1, characterized in that, It includes a first reverse unwinding mechanism (2) and a compounding mechanism (5). A feeding mechanism (3) is installed on the right side of the first reverse unwinding mechanism (2). A first corona treater (9) is installed on the top of the feeding mechanism (3). The first corona treater (9) is connected to a printing and drying device (4) at the top. A single-screw extruder (1) is installed on the top of the compounding mechanism (5). A second reverse unwinding mechanism (6) is connected to the right side of the compounding mechanism (5). A second corona treater (10) is installed between the compounding mechanism (5) and the second reverse unwinding mechanism (6). A film slitting and powder spraying mechanism (7) is connected to the right side of the second reverse unwinding mechanism (6). A third reverse winding mechanism (8) is connected to the right side of the film slitting and powder spraying mechanism (7).

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