Uv-aging resistant drag-reducing film and its preparation process

Abstract

The application relates to the technical field of drag reduction film, and particularly discloses a kind of ultraviolet ageing-resistant drag reduction film and its preparation process, the application introduces hindered amine light stabilizer HALs and silane coupling agent KH-560 in base TPU resin, the strength, heat resistance and ageing resistance of the material are enhanced, then a glue layer is formed on the base film, the disulfide bond in the glue layer has the function of reversible fracture-self-repair, the fatigue resistance and long service life of the material are enhanced, the surface layer is acrylic resin formed by copolymerization, the structure contains flexible alkyl chain and siloxane segment, microstructure is formed by hot rolling, air dynamic performance is optimized, and the purpose of reducing frictional resistance is achieved.

Description

Technical Field

[0001] This invention relates to the field of drag-reducing membrane technology, specifically to a drag-reducing membrane resistant to ultraviolet aging and its preparation process. Background Technology

[0002] Drag-reducing membranes are composite membranes with microstructures on their surface. These microstructures actively disturb the laminar flow structure at the boundary, suppressing turbulence intensity and thus reducing boundary drag. They are commonly used on the outer surfaces of transportation vehicles such as aircraft, high-speed trains, and ships. By reducing the drag experienced by vehicles during operation, they improve transportation efficiency and reduce energy consumption.

[0003] During the use of drag-reducing membranes, their service life is affected by various factors such as fluid impact and ultraviolet radiation. In the high altitudes of aircraft flight, in the oceans of ship navigation, and in areas with strong sunlight, the intensity of ultraviolet radiation can be two to three times that of normal urban outdoor ultraviolet radiation. Prolonged exposure to such high-intensity ultraviolet radiation environments leads to rapid aging and failure of the drag-reducing membrane. The surface microstructure morphology of the membrane is damaged, the surface energy increases, and the drag-reducing efficiency is affected. Therefore, improving the ultraviolet aging resistance of drag-reducing membranes is of great significance for improving their environmental adaptability and service life. Summary of the Invention

[0004] The purpose of this invention is to provide a drag-reducing film resistant to ultraviolet aging and its preparation process, thereby improving the ultraviolet aging resistance of the drag-reducing film, enhancing its environmental adaptability and service life, and solving the problems of insufficient ultraviolet aging resistance, insufficient environmental adaptability, and short service life of drag-reducing films.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A process for preparing a drag-reducing film resistant to ultraviolet aging, specifically as follows:

[0007] Step 1: Modify polycaprolactone-type TPU prepolymer with silane coupling agent KH-560 and hindered amine light stabilizer HALs and extrude to obtain base layer TPU particles;

[0008] Step 2: Prepare disulfide bond modified acrylate adhesive by modifying aliphatic polyurethane acrylate with disulfide urethane.

[0009] Step 3: The silicone-modified acrylic resin and functional additives are co-extruded to obtain silicone-modified acrylic resin particles;

[0010] Step 4: TPU particles are extruded to form a TPU base film. After plasma cleaning, a disulfide bond modified acrylate adhesive is coated and dried to form an adhesive layer on the TPU base film. Silicone-modified acrylic resin particles are extruded and hot-rolled to form a silicone-modified acrylic resin surface layer. The silicone-modified acrylic resin surface layer is laid flat on the adhesive layer. After lamination and photothermal co-curing, a drag-reducing film resistant to ultraviolet aging is obtained.

[0011] As a limitation of the present invention, the method for preparing the base layer TPU particles is as follows:

[0012] Polycaprolactone-type TPU prepolymer, silane coupling agent KH-560, and hindered amine light stabilizer HALs were mixed and added to a twin-screw extruder. The mixture was melt-blended at 170-180℃ and 200-250rpm for 3-5 minutes. Then, polyethylene glycol monoacrylate was added, and the speed was increased to 300-350rpm. The mixture was then blended for another 5-10 minutes. Finally, benzoyl peroxide was added at the end of the extruder and the mixture was extruded at an extrusion temperature of 190-200℃, a screw speed of 200-250rpm, and a die temperature of 170-180℃ to obtain the base layer TPU particles.

[0013] As a limitation of the present invention, the base layer TPU particles, by weight, comprise: 85-95 parts of polycaprolactone-type TPU prepolymer, 1-2 parts of polyethylene glycol monoacrylate, 3-5 parts of silane coupling agent KH-560, 1.5-2.5 parts of hindered amine light stabilizer HALs, and 1-2 parts of benzoyl peroxide.

[0014] During the extrusion process, the silane coupling agent KH-560 hydrolyzes to generate silanol groups (-Si(OH)3), which undergo a condensation reaction with the hydroxyl groups (-OH) at the end of the TPU prepolymer molecular chain to form a covalent bond (-Si-O-). The silane coupling agent KH-560 is then grafted onto the TPU prepolymer. Subsequently, the epoxy group (-CH(O)CH-) at the other end of the silane coupling agent undergoes a ring-opening reaction with the amino group (-NH-) of the hindered amine light stabilizer HALs to form a covalent bond (-O-CH2-CH-NH-). HALs are also grafted onto the TPU prepolymer, improving the material's aging resistance. Finally, under the action of the crosslinking agent benzoyl peroxide, the TPU prepolymer polymerizes to form a three-dimensional crosslinked network. The formation of the crosslinked structure enhances the material's... The process enhances strength and heat resistance, improves the stress transfer capacity within the material, and reduces the propagation of microcracks during aging. Furthermore, the introduction of polyethylene glycol monoacrylate (PEG) during the process allows the acrylate groups (-COOCH=CH2) on the PEG molecule to bond with the terminal hydroxyl groups (-OH) of TPU or the epoxy groups (-CH(O)CH-) of KH-560 through hydrogen bonds or covalent bonds. The flexible PEG segments improve the compatibility between the TPU substrate and the acrylate adhesive layer. The ether bonds (-O-) in the PEG molecule can also form a hydrogen bond network with the polar groups (-COOH, -OH) in the adhesive layer, further enhancing the bonding strength between the TPU substrate and the adhesive layer, thereby improving the material's peel resistance.

[0015] As a limitation of the present invention, the preparation method of the disulfide bond modified acrylate adhesive is as follows:

[0016] Aliphatic polyurethane acrylate was added to butyl acetate and dissolved by magnetic stirring at 50-60℃ and 300-400rpm for 20-30 minutes. Then, dithiocarbamate was added and stirring was continued for 5-10 minutes. The temperature was lowered to 35-45℃, and silane coupling agent KH-560 and benzoyl peroxide were added. The mixture was stirred evenly and ultrasonically dispersed for 20-30 minutes to obtain disulfide bond modified acrylate adhesive.

[0017] As a limitation of the present invention, the disulfide-modified acrylate adhesive comprises, by weight: 60-70 parts aliphatic polyurethane acrylate, 40-60 parts butyl acetate, 2-4 parts dithiocarbamate, 1.5-2.5 parts silane coupling agent KH-560, and 1-2 parts benzoyl peroxide.

[0018] In adhesives, the thiocarbamate groups (-NH-C(=S)-NH-) or thioether bonds (-S-) of dithiocarbamate copolymerize with the carbon-carbon double bonds (-C=C-) of aliphatic polyurethane acrylate through free radical addition reactions to form a crosslinked network. The disulfide bonds (-SS-) of dithiocarbamate are embedded in the aliphatic polyurethane acrylate molecular chain. The disulfide bond energies are moderate, and they can undergo reversible fracture-recombination under light or heat conditions, absorbing interfacial stress and repairing microcracks, thus enhancing the fatigue resistance of the material. Durability and long service life; the epoxy group (-CH(O)CH-) in the structure of silane coupling agent KH-560 undergoes a condensation reaction with the terminal hydroxyl group (-OH) at the end of the molecular chain to form a covalent bond (-Si-O-), which is anchored in the adhesive. The silanol group (-Si(OH)3) forms a covalent bond with the hydroxyl group (-OH) of the TPU base film, thereby improving the interfacial bonding strength; benzoyl peroxide initiates free radical polymerization to form a three-dimensional cross-linked network, which improves the tensile strength and heat resistance of the material.

[0019] As a limitation of this invention, the preparation method of the organosilicon-modified acrylic resin particles is as follows:

[0020] Silicone-modified acrylic resin, hindered amine light stabilizer HALs, and antioxidant 1010 were added to a twin-screw extruder and mixed at 140-150℃ for 5-10 minutes. Then, photoinitiator 1173 was added at the end of the extruder and extruded. The extrusion temperature was set to 160-170℃ and the die temperature was set to 150-160℃ to obtain silicone-modified acrylic resin granules.

[0021] As a limitation of the present invention, the preparation method of the organosilicon-modified acrylic resin is as follows:

[0022] Under nitrogen protection, butyl acrylate is added to the solvent butyl acetate and dissolved by magnetic stirring at 300-400 rpm for 20-30 minutes at 60-70℃. The stirring speed is then increased to 500-600 rpm, and KH-570 modified butyl acrylate, pentaerythritol tetraacrylate, and acrylic acid are added. After stirring for another 20-30 minutes, benzoyl peroxide is added, and the reaction is carried out at 500-90℃ for 3-5 hours at 500-600 rpm. After the reaction is completed, the mixture is dried under vacuum at 50-60℃ to remove the solvent butyl acetate, yielding the organosilicon-modified acrylic resin.

[0023] By weight, the silicone-modified acrylic resin includes: 50-70 parts butyl acrylate, 30-50 parts solvent butyl acetate, 25-35 parts KH-570 modified butyl acrylate, 15-25 parts pentaerythritol tetraacrylate, 10-20 parts acrylic acid and 1-3 parts benzoyl peroxide.

[0024] The preparation method of KH-570 modified butyl acrylate is as follows:

[0025] Silane coupling agent KH-570 and deionized water were added to butyl acetate solvent and stirred until homogeneous. The pH was adjusted to 5-6, and hydrolysis was carried out at 60-70℃ for 3-4 hours. Then, under nitrogen protection, butyl acrylate and benzoyl peroxide were added, and the reaction was carried out at 70-80℃ for 4-5 hours. After the reaction was completed, the mixture was washed with acetone and dried at 50-60℃ for 8-12 hours to obtain KH-570 modified butyl acrylate.

[0026] The mass ratio of butyl acrylate to silane coupling agent KH-570 is (48-52):1.

[0027] Butyl acrylate, KH-570 modified butyl acrylate, pentaerythritol acrylate, and acrylic acid are copolymerized to form a modified acrylic resin containing siloxane segments. The butyl acrylate structure contains long-chain alkyl groups, providing flexible segments during polymerization and enhancing the resin's flexibility. The siloxane segments in the KH-570 modified butyl acrylate structure are bonded to the resin backbone via hydrogen bonds or covalent bonds, forming a siloxane-acrylate interpenetrating network, improving the resin's strength, weather resistance, and long-term stability. Acrylic acid plays a role in regulating polarity during copolymerization; the polar carboxyl groups (-COOH) of acrylic acid can form hydrogen bonds with polar groups in the substrate or adhesive layer, such as urethane bonds (-NHCO-), enhancing the bonding strength between the resin and the substrate or adhesive layer. Pentaerythritol acrylate, as a crosslinking monomer, contains four acrylates in its structure. Under the action of an initiator, it forms a multi-branched crosslinked structure, reducing the resin's molecular weight distribution, resulting in more uniform molecular chain length, and improving the resin's strength and processing performance.

[0028] As a limitation of the present invention, the organosilicon-modified acrylic resin particles, by weight, comprise: 80-90 parts organosilicon-modified acrylic resin, 0.3-0.5 parts hindered amine light stabilizer (HALs), 0.1-0.3 parts antioxidant 1010, and 1-3 parts photoinitiator 1173.

[0029] As a limitation of the present invention, the process parameters for extruding to form the TPU base film include: screw speed: 250-300 rpm, extrusion temperature: 180-190℃, and die temperature: 170-180℃; during plasma cleaning, argon and oxygen are introduced, and the process parameters include: argon flow rate: 70-80 sccm, oxygen flow rate: 20-30 sccm, plasma power supply power: 80-100W, and cleaning time: 1-3 min; when forming the adhesive layer... The drying process parameters include: drying temperature: 60-70℃, drying time: 15-20min; when extruding and hot rolling molding, the process parameters include: melt temperature: 170-180℃, extrusion temperature: 160-170℃, rolling temperature: 130-140℃, rolling pressure: 0.3-0.7MPa; the base film thickness is 30-50μm; the adhesive layer thickness is 20-30μm; and the surface layer thickness of the silicone-modified acrylic resin is 30-50μm.

[0030] After extrusion to form the TPU base film, plasma cleaning is performed. Under the action of active particles in the plasma, residual additives and other contaminants adhering to the surface during the extrusion process are removed. During the process, the active particles react with the CH bonds on the surface of the TPU base film, introducing polar groups (-OH, -COOH), increasing surface polarity, and simultaneously increasing surface roughness. The two work synergistically to enhance the bonding strength between the base film and the adhesive layer. Silicone-modified acrylic resin particles are formed under the hot rolling action of the die roller, forming microstructures on the surface, thereby optimizing aerodynamic performance and reducing frictional resistance.

[0031] A drag-reducing film resistant to ultraviolet aging is prepared by any of the preparation methods described above.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] This invention introduces hindered amine light stabilizer HALs and silane coupling agent KH-560 into the base TPU resin. One end of the silane coupling agent is connected to the hindered amine light stabilizer, and the other end is connected to the TPU molecular chain, significantly enhancing the material's strength, heat resistance, and aging resistance. An adhesive layer is formed on the base film. The disulfide bonds of the dithiocarbamate in the adhesive layer absorb interfacial stress and repair microcracks, enhancing the material's fatigue resistance and long-term service life. The silane coupling agent KH-560 forms covalent bonds with the hydroxyl groups of the TPU base film through silanol groups, improving the interfacial bonding strength. The surface layer is a copolymerized acrylic resin containing flexible alkyl chains and siloxane segments, improving the resin's strength, weather resistance, and long-term stability. The surface layer is formed into a microstructure through hot rolling, optimizing aerodynamic performance and reducing frictional resistance. Detailed Implementation

[0034] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. 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.

[0035] Polycaprolactone-based TPU prepolymer (Mn=2000), polyethylene glycol monoacrylate (Mw=2000, hydroxyl value: 50mgKOH / g), aliphatic polyurethane acrylate (viscosity: 2000mPa·s), thermoplastic polyurethane resin particles (Mn=20000, viscosity: 25000mPa·s), acrylate adhesive (Mn=10000, viscosity: 8000mPa·s), thermosetting acrylic resin (Mn=8000, viscosity: 3000mPa·s).

[0036] The preparation method of KH-570 modified butyl acrylate is as follows:

[0037] 2g of silane coupling agent KH-570 and 2g of deionized water were added to 100mL of butyl acetate solvent, stirred evenly, and the pH was adjusted to 6. After hydrolysis at 60℃ for 3h, 100g of butyl acrylate and 1g of benzoyl peroxide were added under nitrogen protection, and the reaction was carried out at 80℃ for 5h. After the reaction was completed, the mixture was washed with acetone and dried at 50℃ for 12h to obtain KH-570 modified butyl acrylate.

[0038] Example 1: A process for preparing a drag-reducing film resistant to ultraviolet aging, specifically as follows:

[0039] Step 1: Mix 95g of polycaprolactone-type TPU prepolymer, 3g of silane coupling agent KH-560 and 1.5g of hindered amine light stabilizer HALs, add to a twin-screw extruder, melt-blend at 180℃ and 200rpm for 5min, then add 1g of polyethylene glycol monoacrylate, increase the speed to 350rpm, continue blending for 10min, then add 1g of benzoyl peroxide at the end of the extruder and extrude at 190℃, screw speed of 200rpm, and die temperature of 170℃ to obtain base layer TPU particles;

[0040] Step 2: Add 70g of aliphatic polyurethane acrylate to 60g of butyl acetate, and dissolve it by magnetic stirring at 55℃ and 400rpm for 30min. Then add 2g of dithiocarbamate and continue stirring for 10min. Cool down to 40℃, add 1.5g of silane coupling agent KH-560 and 1g of benzoyl peroxide, stir evenly, and ultrasonically disperse for 20min to obtain disulfide bond modified acrylate adhesive.

[0041] Step 3: Under nitrogen protection, 70g of butyl acrylate was added to 50g of butyl acetate solvent. The mixture was magnetically stirred at 300rpm for 30min at 60℃ to dissolve it. The stirring speed was increased to 500rpm, and 25g of KH-570 modified butyl acrylate, 15g of pentaerythritol tetraacrylate and 10g of acrylic acid were added. After stirring for another 30min, 1.5g of benzoyl peroxide was added. The mixture was reacted at 500rpm for 4h at 80℃. After the reaction was completed, the mixture was vacuum dried at 60℃ to remove the butyl acetate solvent, and the silicone-modified acrylic resin was obtained.

[0042] Step 4: Add 90g of silicone-modified acrylic resin, 0.3g of hindered amine light stabilizer HALs and 0.1g of antioxidant 1010 to a twin-screw extruder. After mixing at 150℃ for 10min, add 1.5g of photoinitiator 1173 at the end of the extruder. Set the extrusion temperature to 170℃ and the die temperature to 160℃ to obtain silicone-modified acrylic resin granules.

[0043] Step 5: Add the TPU base layer particles to the extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning by introducing argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 minutes. After cleaning, coat the surface with a disulfide bond modified acrylate adhesive. Coating complete. After drying at 65℃ for 20 minutes, an adhesive layer with a thickness of 20μm is formed. Silicone-modified acrylic resin granules are then added to a twin-screw extruder for extrusion and rolling. The melt temperature is 170℃, the extrusion temperature is 160℃, the rolling temperature is 140℃, and the rolling pressure is 0.5MPa, forming a 40μm silicone-modified acrylic resin surface layer. This surface layer is then laid flat on the adhesive layer and laminated at 110℃ and 0.3MPa. Following lamination, photothermal curing is performed using 365nm ultraviolet light with an energy density of 800mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0044] Example 2: A process for preparing a drag-reducing film resistant to ultraviolet aging, specifically as follows:

[0045] Step 1: Mix 90g of polycaprolactone-type TPU prepolymer, 3g of silane coupling agent KH-560 and 1.5g of hindered amine light stabilizer HALs, add to a twin-screw extruder, melt-blend at 180℃ and 200rpm for 5min, then add 1g of polyethylene glycol monoacrylate, increase the speed to 350rpm, continue blending for 10min, then add 1g of benzoyl peroxide at the end of the extruder and extrude at 190℃, screw speed of 200rpm, and die temperature of 170℃ to obtain base layer TPU particles;

[0046] Step 2: Add 65g of aliphatic polyurethane acrylate to 55g of butyl acetate, and dissolve it by magnetic stirring at 55℃ and 400rpm for 30min. Then add 2g of dithiocarbamate and continue stirring for 10min. Cool down to 40℃, add 1.5g of silane coupling agent KH-560 and 1g of benzoyl peroxide, stir evenly, and ultrasonically disperse for 20min to obtain disulfide bond modified acrylate adhesive.

[0047] Step 3: Under nitrogen protection, 60g of butyl acrylate was added to 50g of butyl acetate solvent. The mixture was magnetically stirred at 300rpm for 30min at 60℃ to dissolve it. The stirring speed was increased to 500rpm, and 20g of KH-570 modified butyl acrylate, 20g of pentaerythritol tetraacrylate and 10g of acrylic acid were added. After stirring for another 30min, 1.5g of benzoyl peroxide was added. The mixture was reacted at 500rpm for 4h at 80℃. After the reaction was completed, the mixture was vacuum dried at 60℃ to remove the butyl acetate solvent, and the silicone-modified acrylic resin was obtained.

[0048] Step 4: Add 85g of silicone-modified acrylic resin, 0.6g of hindered amine light stabilizer HALs and 0.3g of antioxidant 1010 to a twin-screw extruder. After mixing at 150℃ for 10min, add 1.5g of photoinitiator 1173 at the end of the extruder. Set the extrusion temperature to 170℃ and the die temperature to 160℃ to obtain silicone-modified acrylic resin granules.

[0049] Step 5: Add the TPU base layer particles to the extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning by introducing argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 minutes. After cleaning, coat the surface with a disulfide bond modified acrylate adhesive. Coating complete. After drying at 65℃ for 20 minutes, an adhesive layer with a thickness of 20μm is formed. Silicone-modified acrylic resin granules are then added to a twin-screw extruder for extrusion and rolling. The melt temperature is 170℃, the extrusion temperature is 160℃, the rolling temperature is 140℃, and the rolling pressure is 0.5MPa, forming a 50μm silicone-modified acrylic resin surface layer. This surface layer is then spread evenly on the adhesive layer and laminated at 110℃ and 0.3MPa. Following lamination, photothermal curing is performed using 365nm ultraviolet light with an energy density of 800mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0050] Example 3: A process for preparing a drag-reducing film resistant to ultraviolet aging, specifically as follows:

[0051] Step 1: Mix 85g of polycaprolactone-type TPU prepolymer, 3g of silane coupling agent KH-560 and 1.5g of hindered amine light stabilizer HALs, add to a twin-screw extruder, melt-blend at 180℃ and 200rpm for 5min, then add 1g of polyethylene glycol monoacrylate, increase the speed to 350rpm, continue blending for 10min, then add 1g of benzoyl peroxide at the end of the extruder and extrude at 190℃, screw speed of 200rpm, and die temperature of 170℃ to obtain base layer TPU particles;

[0052] Step 2: Add 60g of aliphatic polyurethane acrylate to 50g of butyl acetate, and dissolve it by magnetic stirring at 55℃ and 400rpm for 30min. Then add 2g of dithiocarbamate and continue stirring for 10min. Cool down to 40℃, add 1.5g of silane coupling agent KH-560 and 1g of benzoyl peroxide, stir evenly, and ultrasonically disperse for 20min to obtain disulfide bond modified acrylate adhesive.

[0053] Step 3: Under nitrogen protection, 50g of butyl acrylate was added to 50g of butyl acetate solvent and dissolved by magnetic stirring at 300rpm for 30min at 60℃. The stirring speed was increased to 500rpm, and 25g of KH-570 modified butyl acrylate, 25g of pentaerythritol tetraacrylate and 20g of acrylic acid were added. After stirring for another 30min, 1.5g of benzoyl peroxide was added and reacted at 500rpm for 4h at 80℃. After the reaction was completed, the product was dried under vacuum at 60℃ to remove the butyl acetate solvent and obtain the organosilicon modified acrylic resin.

[0054] Step 4: Add 80g of silicone-modified acrylic resin, 0.6g of hindered amine light stabilizer HALs and 0.3g of antioxidant 1010 to a twin-screw extruder. After mixing at 150℃ for 10min, add 1.5g of photoinitiator 1173 at the end of the extruder. Set the extrusion temperature to 170℃ and the die temperature to 160℃ to obtain silicone-modified acrylic resin granules.

[0055] Step 5: Add the TPU base layer particles to the extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning by introducing argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 minutes. After cleaning, coat the surface with a disulfide bond modified acrylate adhesive. Coating complete. After drying at 65℃ for 20 minutes, an adhesive layer with a thickness of 30μm is formed. Silicone-modified acrylic resin granules are then added to a twin-screw extruder for extrusion and rolling. The melt temperature is 170℃, the extrusion temperature is 160℃, the rolling temperature is 140℃, and the rolling pressure is 0.5MPa, forming a 50μm silicone-modified acrylic resin surface layer. This surface layer is then spread evenly on the adhesive layer and laminated at 110℃ and 0.3MPa. Following lamination, photothermal curing is performed using 365nm ultraviolet light with an energy density of 800mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0056] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0057] Comparative Example 1: This comparative example relates to a preparation process of a drag-reducing film resistant to ultraviolet aging. The difference from Example 1 is that the base film is prepared using thermoplastic polyurethane particles, specifically:

[0058] Step 1: Add 70g of aliphatic polyurethane acrylate to 60g of butyl acetate, and dissolve it by magnetic stirring at 55℃ and 400rpm for 30min. Then add 2g of dithiocarbamate and continue stirring for 10min. Cool down to 40℃, add 1.5g of silane coupling agent KH-560 and 1g of benzoyl peroxide, stir evenly, and ultrasonically disperse for 20min to obtain disulfide bond modified acrylate adhesive.

[0059] Step 2: Under nitrogen protection, 70g of butyl acrylate was added to 50g of butyl acetate solvent and dissolved by magnetic stirring at 300rpm for 30min at 60℃. The stirring speed was increased to 500rpm, and 25g of KH-570 modified butyl acrylate, 15g of pentaerythritol tetraacrylate and 10g of acrylic acid were added. After stirring for another 30min, 1.5g of benzoyl peroxide was added and reacted at 500rpm for 4h at 80℃. After the reaction was completed, the product was dried under vacuum at 60℃ to remove the butyl acetate solvent and obtain the organosilicon modified acrylic resin.

[0060] Step 3: Add 90g of silicone-modified acrylic resin, 0.3g of hindered amine light stabilizer HALs and 0.1g of antioxidant 1010 to a twin-screw extruder. After mixing at 150℃ for 10min, add 1.5g of photoinitiator 1173 at the end of the extruder. Set the extrusion temperature to 170℃ and the die temperature to 160℃ to obtain silicone-modified acrylic resin granules.

[0061] Step 4: Add thermoplastic polyurethane granules to an extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning by introducing argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 minutes. After cleaning, coat the surface with a disulfide-modified acrylate adhesive. Coating complete. After drying at 65℃ for 20 minutes, an adhesive layer with a thickness of 20μm is formed. Silicone-modified acrylic resin granules are then added to a twin-screw extruder for extrusion and rolling. The melt temperature is 170℃, the extrusion temperature is 160℃, the rolling temperature is 140℃, and the rolling pressure is 0.5MPa, forming a 50μm silicone-modified acrylic resin surface layer. This surface layer is then spread evenly on the adhesive layer and laminated at 110℃ and 0.3MPa. Following lamination, photothermal curing is performed using 365nm ultraviolet light with an energy density of 800mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0062] Comparative Example 2: This comparative example relates to a preparation process for a drag-reducing film resistant to UV aging. The difference from Example 1 is the use of an unmodified acrylate adhesive, specifically:

[0063] Step 1: Mix 95g of polycaprolactone-type TPU prepolymer, 3g of silane coupling agent KH-560 and 1.5g of hindered amine light stabilizer HALs, add to a twin-screw extruder, melt-blend at 180℃ and 200rpm for 5min, then add 1g of polyethylene glycol monoacrylate, increase the speed to 350rpm, continue blending for 10min, then add 1g of benzoyl peroxide at the end of the extruder and extrude at 190℃, screw speed of 200rpm, and die temperature of 170℃ to obtain base layer TPU particles;

[0064] Step 2: Under nitrogen protection, 70g of butyl acrylate was added to 50g of butyl acetate solvent and dissolved by magnetic stirring at 300rpm for 30min at 60℃. The stirring speed was increased to 500rpm, and 25g of KH-570 modified butyl acrylate, 15g of pentaerythritol tetraacrylate and 10g of acrylic acid were added. After stirring for another 30min, 1.5g of benzoyl peroxide was added and reacted at 500rpm for 4h at 80℃. After the reaction was completed, the product was dried under vacuum at 60℃ to remove the butyl acetate solvent and obtain the organosilicon modified acrylic resin.

[0065] Step 3: Add 90g of silicone-modified acrylic resin, 0.3g of hindered amine light stabilizer HALs and 0.1g of antioxidant 1010 to a twin-screw extruder. After mixing at 150℃ for 10min, add 1.5g of photoinitiator 1173 at the end of the extruder. Set the extrusion temperature to 170℃ and the die temperature to 160℃ to obtain silicone-modified acrylic resin granules.

[0066] Step 5: Add the TPU base layer particles to the extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning by introducing argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 minutes. After cleaning, coat the surface with acrylic adhesive. After coating, 65... Dry at ℃ for 20 min to form an adhesive layer with a thickness of 20 μm. Add silicone-modified acrylic resin granules to a twin-screw extruder for extrusion and rolling. The melt temperature is 170℃, the extrusion temperature is 160℃, the rolling temperature is 140℃, and the rolling pressure is 0.5 MPa, forming a 50 μm silicone-modified acrylic resin surface layer. Spread the silicone-modified acrylic resin surface layer evenly on the adhesive layer. Laminate at 110℃ and 0.3 MPa, followed by photothermal curing. The light source is 365 nm ultraviolet light with an energy density of 800 mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0067] Comparative Example 3: This comparative example relates to a preparation process for a drag-reducing film resistant to ultraviolet aging. The difference from Example 1 is that a thermosetting acrylic resin is used for the surface layer. Specifically:

[0068] Step 1: Mix 95g of polycaprolactone-type TPU prepolymer, 3g of silane coupling agent KH-560 and 1.5g of hindered amine light stabilizer HALs, add to a twin-screw extruder, melt-blend at 180℃ and 200rpm for 5min, then add 1g of polyethylene glycol monoacrylate, increase the speed to 350rpm, continue blending for 10min, then add 1g of benzoyl peroxide at the end of the extruder and extrude at 190℃, screw speed of 200rpm, and die temperature of 170℃ to obtain base layer TPU particles;

[0069] Step 2: Add 70g of aliphatic polyurethane acrylate to 60g of butyl acetate, and dissolve it by magnetic stirring at 55℃ and 400rpm for 30min. Then add 2g of dithiocarbamate and continue stirring for 10min. Cool down to 40℃, add 1.5g of silane coupling agent KH-560 and 1g of benzoyl peroxide, stir evenly, and ultrasonically disperse for 20min to obtain disulfide bond modified acrylate adhesive.

[0070] Step 3: Add the TPU base layer particles to an extruder and extrude to form a film. Set the screw speed to 300 rpm, the extrusion temperature to 190℃, and the die temperature to 180℃ to obtain a TPU base film with a thickness of 50 μm. Transfer the TPU base film to a plasma device and perform plasma cleaning with argon and oxygen. Set the argon flow rate to 70 sccm, the oxygen flow rate to 30 sccm, the plasma power to 100W, and the cleaning time to 3 min. After cleaning, coat the surface with a disulfide bond modified acrylate adhesive. After coating, dry at 65℃ for 20 min to form an adhesive layer with a thickness of 20 μm. Spread thermosetting acrylic resin particles evenly over the adhesive layer and roll it at 130℃ with a die roller at a pressure of 0.5 MPa to form a 40 μm acrylic resin surface layer. After rolling, perform photothermal co-curing using 365nm ultraviolet light with an energy density of 800 mJ / cm². 2 The thermosetting temperature was 120℃ and the curing time was 20min, resulting in a drag-reducing film resistant to ultraviolet aging.

[0071] Testing experiment:

[0072] UV-resistant drag-reducing film test samples were prepared according to each embodiment and comparative example. They were cut into dumbbell-shaped specimens (total specimen length 150mm, specimen width 25mm, narrow parallel section length 33mm, narrow parallel section width 6mm, gauge length 25mm) and subjected to tensile strength test, UV aging resistance test, damp heat aging resistance test, and fatigue performance test.

[0073] Tensile strength test: The tensile strength test of the drag-reducing film is conducted in accordance with "Determination of tensile properties of plastics - Part 3: Test conditions for films and sheets" (GB / T 1040.3-2006). The dumbbell-shaped specimen is clamped and fixed at both ends with the upper and lower clamps of the universal testing machine. The testing machine is started and stretched at a tensile rate of 50 mm / min until the specimen breaks. The maximum load and the gauge length elongation at break are recorded. The tensile strength of the specimen is calculated. Each drag-reducing film is tested 5 times, and the average value of the test results is taken.

[0074] UV aging resistance test: The UV aging resistance test of the drag-reducing film was conducted in accordance with "Laboratory Light Source Exposure Test Methods for Plastics - Part 3: Fluorescent Ultraviolet Lamp" (GB / T 16422.3-2022). Five samples of each drag-reducing film were selected and placed in a UV aging test chamber. The temperature inside the chamber was 60℃, the irradiation source was 365nm ultraviolet light, and the irradiation intensity was 0.89W / m². 2 After aging for 500 hours, the sample was taken out and its tensile strength was measured. The average value of the test results was taken, and the tensile strength retention rate of the sample was calculated.

[0075] Damp heat aging resistance test: The damp heat aging resistance test of the drag-reducing membrane refers to the "Technical Conditions for Damp Heat Test Chamber" (GB / T 10586-2006). Five samples of each drag-reducing membrane are selected and placed in the damp heat test chamber. The temperature inside the aging chamber is 85℃ and the relative humidity is 85%RH. After aging for 500 hours, the samples are taken out and the tensile strength after aging is measured. The average value of the test results is taken, and the tensile strength retention rate of the samples is calculated.

[0076] Fatigue performance testing: A high-frequency fatigue testing machine was used for fatigue performance testing. Ten specimens of each drag-reducing membrane were selected and placed on the test bench of the machine, and fixed with clamps. The machine was started, and tensile stress was applied in sinusoidal mode. The loading frequency was set to 10 Hz, the cyclic stress ratio was 0.1, and the maximum cyclic stress was set to 70% of the stress corresponding to the tensile strength of the specimen. The test was performed for 10 cycles. 6 After one test, the tensile strength retention rate of the specimen was measured.

[0077]

[0078] Conclusion: The test data shows that, compared with the test results of the comparative examples, the tensile strength of the drag-reducing film resistant to UV aging provided in the examples is better than that of the comparative examples. After UV aging, damp heat aging, or fatigue cycling, the tensile strength retention rate of the drag-reducing film resistant to UV aging prepared in the examples is still higher than that of the comparative examples. The drag-reducing film resistant to UV aging prepared in the examples has good tensile strength, UV aging resistance, damp heat aging resistance, and long service life, and can solve the problems of poor UV aging resistance, weak environmental usability, and insufficient long service life of drag-reducing films.

[0079] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A process for the preparation of a UV-aging resistant drag-reducing film, characterized in that: Specifically: Step 1: modify polycaprolactone type TPU prepolymer with silane coupling agent KH-560 and hindered amine light stabilizer HALS and extrude to obtain TPU granules for the base layer; Step 2: use bis-thio-carbamate modified aliphatic polyurethane acrylate to prepare disulfide bond modified acrylate adhesive; Step 3: blend and extrude silicone modified acrylic resin and functional additives to obtain silicone modified acrylic resin granules; Step 4: extrude TPU granules for the base layer to form a TPU base film, coat the disulfide bond modified acrylate adhesive after plasma cleaning and dry, form an adhesive layer on the TPU base film, extrude and hot roll form the silicone modified acrylic resin surface layer, lay the silicone modified acrylic resin surface layer on the adhesive layer, and then perform lamination, photothermal synergistic curing to obtain a UV aging resistant drag reduction film.

2. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 1, characterized in that: The preparation method of the TPU granules for the base layer is as follows: Mix polycaprolactone type TPU prepolymer, silane coupling agent KH-560 and hindered amine light stabilizer HALS, and add them to a twin-screw extruder, melt blend at 170-180°C and 200-250rpm for 3-5min, then add polyethylene glycol monoacrylate, increase the speed to 300-350rpm, continue to blend for 5-10min, then add dibenzoyl peroxide at the end of the extruder and extrude, the extrusion temperature is 190-200°C, the screw speed is 200-250rpm, and the die temperature is 170-180°C to obtain the TPU granules for the base layer.

3. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 2, characterized in that: The TPU granules for the base layer include, by mass fraction: 85-95 parts of polycaprolactone type TPU prepolymer, 1-2 parts of polyethylene glycol monoacrylate, 3-5 parts of silane coupling agent KH-560, 1.5-2.5 parts of hindered amine light stabilizer HALS, and 1-2 parts of dibenzoyl peroxide.

4. The process for preparing a UV-aging resistant drag-reducing film according to claim 1, characterized in that: The preparation method of the disulfide bond modified acrylate adhesive is as follows: Add aliphatic polyurethane acrylate to butyl acetate, dissolve under magnetic stirring at 50-60°C and 300-400rpm for 20-30min, then add bis-thio-carbamate, continue to stir for 5-10min, cool to 35-45°C, add silane coupling agent KH-560 and dibenzoyl peroxide, stir uniformly, and ultrasonic dispersion for 20-30min to obtain the disulfide bond modified acrylate adhesive.

5. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 4, characterized in that: The disulfide bond modified acrylate adhesive includes, by mass fraction: 60-70 parts of aliphatic polyurethane acrylate, 40-60 parts of butyl acetate, 2-4 parts of bis-thio-carbamate, 1.5-2.5 parts of silane coupling agent KH-560, and 1-2 parts of dibenzoyl peroxide.

6. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 1, characterized in that: The preparation method of the silicone modified acrylic resin granules is as follows: The silicone-modified acrylic resin, the hindered amine light stabilizer HALS and the antioxidant 1010 are added into a double-screw extruder, and after mixing at 140-150℃ for 5-10 min, the photoinitiator 1173 is added at the end of the extruder and extruded, with the extrusion temperature set at 160-170℃ and the die temperature set at 150-160℃, to obtain silicone-modified acrylic resin particles.

7. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 6, characterized in that: The silicone-modified acrylic resin is prepared by the following method: Under nitrogen protection, the butyl acrylate is added into the solvent butyl acetate, dissolved at 60-70℃ under magnetic stirring at 300-400 rpm for 20-30 min, the stirring speed is increased to 500-600 rpm, the butyl acrylate is modified by KH-570, pentaerythritol tetraacrylate and acrylic acid are added, and after continuous stirring for 20-30 min, the benzoyl peroxide is added, and the reaction is carried out at 80-90℃ under stirring at 500-600 rpm for 3-5 h, and after the reaction is completed, the solvent butyl acetate is removed by vacuum drying at 50-60℃, to obtain the silicone-modified acrylic resin.

8. The process for the preparation of a UV-aging resistant drag-reducing film according to claim 6, characterized in that: The silicone-modified acrylic resin particles include, by mass fraction, 80-90 parts of silicone-modified acrylic resin, 0.3-0.5 parts of hindered amine light stabilizer HALS, 0.1-0.3 parts of antioxidant 1010 and 1-3 parts of photoinitiator 1173.

9. The process for the preparation of a UV ageing resistant drag reducing film according to claim 1, characterized in that: When the TPU base film is formed by extrusion, the process parameters include a screw rotation speed of 250-300 rpm, an extrusion temperature of 180-190℃ and a die temperature of 170-180℃. When the plasma cleaning is carried out, argon and oxygen are introduced, and the process parameters include an argon flow rate of 70-80 sccm, an oxygen flow rate of 20-30 sccm, a plasma power of 80-100 W and a cleaning time of 1-3 min; when the adhesive layer is formed, the drying process parameters include a drying temperature of 60-70℃ and a drying time of 15-20 min; when the extrusion and hot rolling are carried out, the process parameters include a melting temperature of 170-180℃, an extrusion temperature of 160-170℃, a rolling temperature of 130-140℃ and a rolling pressure of 0.3-0.7 MPa; the base film has a thickness of 30-50 μm; the adhesive layer has a thickness of 20-30 μm; and the silicone-modified acrylic resin surface layer has a thickness of 30-50 μm. The silicone-modified acrylic resin is prepared by the method of any one of claims 1-9.

10. A UV-aging resistant drag-reducing film characterized in that: ​

Images