High weatherable metal clad plastic polymeric material and method of manufacture

Abstract

The application discloses a kind of high weatherability metal covering plastic polymeric materials and preparation method, it is related to metal wire processing technical field, the material is coated in the double-layer plastic structure outside metal base material, inner layer contains hyperbranched polyester resin, fluorine silicon block copolymer and corrosion-inhibiting fluorescent microcapsule, release corrosion inhibitor and emit red fluorescence when breakage, outer layer contains ternary ethylene-propylene rubber graft maleic anhydride polymer, ethylene-octene copolymer and stress response type fluorescent probe-silica core-shell nanoparticles, activate and emit blue fluorescence under stress.By ultraviolet lamp irradiation, according to blue, red fluorescence or both coexistence can in situ judge outer layer, inner layer or double-layer breakage position.The application has high adhesion, high weatherability and breakage layer position self-diagnosis function, and is suitable for outdoor fence, silk screen products and other fields.

Description

Technical Field

[0001] This invention relates to the field of metal wire processing technology, specifically to a high weather-resistant metal coated polymer material and its preparation method. Background Technology

[0002] Metal wires are widely used in outdoor engineering, fencing, wire mesh, bridge cables, and other applications. To prevent the metal substrate from being corroded in harsh climates and corrosive environments, a common protective measure is to coat the surface of the metal wire with a layer of polymer material. However, existing coating materials often face the challenge of balancing the performance of adhesion, weather resistance, and abrasion resistance. For example, adding polar functional groups to improve adhesion may reduce the material's weather resistance; while adding high-filler materials to improve weather resistance may lead to decreased toughness and interface detachment.

[0003] More importantly, when existing coated wires experience localized cracking during service, operators often cannot promptly and accurately determine which layer (inner or outer layer) the damage occurred, making it difficult to develop targeted repair or replacement plans. Traditional testing methods often require destructive sampling, which is time-consuming, labor-intensive, and cannot achieve in-situ testing. Therefore, developing a coated material that combines excellent weather resistance with the ability to in-situ and intuitively indicate the location of the damaged layer is of significant practical importance. Consequently, those skilled in the art provide a high weather-resistant metal coated polymer material and its preparation method to address the problems mentioned above. Summary of the Invention

[0004] The purpose of this invention is to provide a high weather-resistant metal-coated polymer material and its preparation method to solve the problems raised in the prior art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] The inner layer is made of the following components in parts by weight: 40-60 parts of hyperbranched polyester resin, 20-35 parts of fluorosilicone block copolymer, 5-15 parts of first-type corrosion-inhibiting fluorescent microcapsules, 8-12 parts of liquid polybutadiene toughening agent, 3-8 parts of nano-hydrotalcite, and 1-3 parts of hindered amine light stabilizer.

[0007] In a preferred embodiment, the hyperbranched polyester resin is a hydroxyl-terminated hyperbranched polyester with a number-average molecular weight of 2000-5000. Its unique hyperbranched topology provides a large number of terminal hydroxyl groups and branching points. These hydroxyl groups can form hydrogen bonds or coordination bonds with the oxide layer (such as iron oxide or zinc oxide) on the surface of the metal substrate, thereby significantly improving the interfacial adhesion between the inner layer and the metal substrate. Simultaneously, the hyperbranched structure imparts a lower melt viscosity to the resin, which is beneficial for uniformly coating the metal wire during co-extrusion.

[0008] In a preferred embodiment, the fluorosilicone block copolymer is a polyvinylidene fluoride-polydimethylsiloxane block copolymer (PVDF-b-PDMS), wherein the degree of polymerization of the polyvinylidene fluoride blocks is 100-200, and the degree of polymerization of the polydimethylsiloxane blocks is 50-100. The polyvinylidene fluoride (PVDF) segments provide excellent chemical stability, UV resistance, and mechanical strength, while the polydimethylsiloxane (PDMS) segments impart extremely low surface energy and hydrophobic and oleophobic properties to the material, making the inner layer excellent in resisting corrosion from water vapor, acidic media, and other corrosive substances. The nanoscale structure formed by the separation of the two block microphases effectively hinders the penetration channels of corrosive media, extending the protective life of the substrate.

[0009] In a preferred embodiment, the liquid polybutadiene toughening agent is hydroxyl-terminated liquid polybutadiene (HTPB) with a number-average molecular weight of 2000-4000. Its terminal hydroxyl groups can form a hydrogen bond network with the hydroxyl groups of the hyperbranched polyester and the hydroxyl groups on the surface of the nano-hydrotalcite, constructing a flexible-rigid interwoven cross-chain structure in the system. This structure can effectively absorb and dissipate energy under impact or low-temperature shrinkage, avoiding brittle fracture and ensuring that the inner layer maintains excellent impact resistance even at low temperatures (e.g., -40°C).

[0010] In a preferred embodiment, the hindered amine light stabilizer is selected from light stabilizer 770, light stabilizer 622 or a combination thereof, and is used in an amount of 1-3 parts. Its main function is to provide basic photo-oxidation protection for the inner layer and prevent the inner layer from being degraded by ultraviolet radiation penetrating the outer layer during long-term use.

[0011] The core material of the microcapsule is a complex of 8-hydroxyquinoline and rhodamine B (preferably in a mass ratio of 3:1-5:1), and the wall material is polyurea resin. Under normal conditions, the microcapsule wall remains intact, and the core material is encapsulated inside, not participating in the matrix reaction or emitting light. When the inner layer is subjected to external stress (such as tension, bending, or impact) and cracks or breaks, the microcapsule wall along the crack propagation path ruptures, releasing the core material. 8-hydroxyquinoline, as a typical organic corrosion inhibitor, can form stable chelates with metal ions (such as Fe²⁺ and Zn²⁺), generating a dense protective film in situ at the site of damage, thereby actively inhibiting the propagation of localized corrosion and acting as a "healing" agent. Rhodamine B is a high-yield fluorescent dye that emits bright red fluorescence under ultraviolet light (365 nm) excitation, indicating the location of the inner layer damage. The preferred mass ratio of microcapsule core material to wall material is 1:2-1:4, and the preferred microcapsule particle size is 1-5μm, so as to ensure that the mechanical strength of the wall material is sufficient to withstand the shearing of the co-extrusion process without premature breakage, and that it can respond sensitively when damage occurs.

[0012] The outer layer is made of the following components in parts by weight: 50-70 parts of EPDM-grafted maleic anhydride polymer, 25-40 parts of ethylene-octene copolymer, 8-18 parts of type II stress-responsive fluorescent probe-silica core-shell nanoparticles, 5-10 parts of nano-silica aerogel, 3-6 parts of titanium dioxide, and 1-2 parts of antioxidant.

[0013] In a preferred embodiment, the grafting rate of EPDM-g-MAH onto maleic anhydride polymer (EPDM-g-MAH) is 1.0%-2.0%, and the Mooney viscosity ML(1+4) at 125°C is 40-60. The EPDM backbone imparts excellent elasticity, weather resistance, and low-temperature resistance to the outer layer, while the maleic anhydride grafting provides good compatibility with polar fillers and matrices (such as hyperbranched polyester in the inner layer), enhancing interlayer bonding.

[0014] In a preferred embodiment, the ethylene-octene copolymer (POE) has an octene content of 15%-25% and a melt index (190°C / 2.16kg) of 1.0-3.0 g / 10min. POE acts as a toughening agent, effectively lowering the glass transition temperature of the outer layer and improving its elastic recovery at low temperatures.

[0015] In a preferred embodiment, the nano-silica aerogel has a specific surface area ≥600m² / g and an average particle size of 10-30nm. Its porosity (greater than 90%) and low thermal conductivity give the outer layer good heat insulation and sound insulation effects, while its nanoscale size enhances the material's rigidity and scratch resistance.

[0016] In a preferred embodiment, the titanium dioxide is rutile type, with an average particle size of 200-400 nm, and is used in an amount of 3-6 parts. As a highly efficient ultraviolet reflector and scattering agent, titanium dioxide can significantly reduce the degradation effect of ultraviolet light on the surface polymer matrix, and is one of the key components in constructing an outer layer of UV protection. Furthermore, titanium dioxide can also adjust the color and hiding power of the outer layer.

[0017] In a preferred embodiment, the antioxidant comprises a hindered phenolic primary antioxidant (such as antioxidant 1010, 1076) and a phosphite secondary antioxidant (such as antioxidant 168), with a mass ratio of 1:1 to 2:1 and a total dosage of 1-2 parts. This compound system can effectively capture free radicals and decompose hydroperoxides, giving the outer layer a long-term thermo-oxidative stability lifetime.

[0018] The "second-type stress-responsive fluorescent probe - silica core-shell nanoparticles" in this invention is the core component for achieving self-diagnosis of outer layer damage stress. These nanoparticles have a "core-shell" structure: the core layer is a mechanochromic molecule (e.g., tetraphenylethylene derivative, TPE), and the shell layer is hollow mesoporous silica, encapsulated with a fluorescence quencher (e.g., nitrobenzodiazole derivative, NBD-Cl, or similar). Under non-stress conditions, the TPE molecules are located within the mesoporous channels of the shell, in close contact with the quencher, effectively quenching the fluorescence. Therefore, the outer layer exhibits weak background fluorescence or a dark color (unobservable) under ultraviolet light. When the outer layer deforms or breaks due to mechanical stress such as scratching, stretching, or impact, the stress is transferred through the polymer matrix to the silica shell of the core-shell nanoparticles, causing microcracks or localized fractures. At this point, the internal TPE molecules are exposed within the polymer matrix, separated from the quencher. Due to the steric hindrance of the TPE molecules, intramolecular rotation is restricted, exciting aggregation-induced emission (AIE) and emitting strong blue fluorescence under ultraviolet light. The intensity of the blue fluorescence is approximately proportional to the applied strain; therefore, the strain level and damage degree of the outer layer can be semi-quantitatively assessed by fluorescence intensity. The preferred particle size of the nanoparticles is 50-200 nm, and the mass ratio of the core layer mechanochromic molecule (TPE derivative) to the encapsulated quencher in the shell is 5:1-10:1 to ensure sufficient quenching (dark background) under no stress and significant fluorescence recovery under stress.

[0019] The present invention provides a plastic-coated environmentally friendly wire, comprising: a metal wire; and a plastic coating layer covering the outside of the metal wire; the plastic coating layer has the above-mentioned double-layer structure, including an inner layer in contact with the surface of the metal wire and an outer layer covering the outside of the inner layer.

[0020] In a preferred embodiment, the metal wire is hot-dip galvanized steel wire, hot-dip high-zinc steel wire, zinc-aluminum alloy steel wire, zinc-aluminum-magnesium alloy steel wire, or copper-clad steel wire. The wire diameter is preferably 1.0-6.0 mm.

[0021] In a preferred embodiment, the total thickness of the plastic coating layer is 0.4-2.0 mm, wherein the inner layer thickness accounts for 40%-60% of the total thickness of the plastic coating layer, i.e., the inner layer thickness is preferably 0.16-1.2 mm, and the corresponding outer layer thickness is 0.24-0.8 mm. The ratio of inner to outer layer thickness can be precisely controlled by the design of the co-extrusion die flow channel and the adjustment of process parameters.

[0022] This invention provides a wire mesh product woven or twisted from the aforementioned plastic-coated environmentally friendly wire. Specific forms of the wire mesh product include, but are not limited to, hexagonal mesh, square mesh, welded wire mesh, and roll mesh (such as gabion mesh), and it is used in slope protection, river management, aquaculture fencing, airport perimeter fencing, and building protection.

[0023] This invention provides a method for preparing the above-mentioned high weather-resistant metal-coated polymer material, comprising the following steps:

[0024] Step S1: Preparation of the inner layer premix. Hyperbranched polyester resin, liquid polybutadiene toughening agent, and type I corrosion-inhibiting fluorescent microcapsules are mixed in a low-speed mixer at 200-400 rpm for 5-10 minutes to uniformly pre-disperse the microcapsules in the liquid resin. Then, fluorosilicone block copolymer, nano-hydrotalcite, and hindered amine light stabilizer are added, and the mixture is stirred at 600-800 rpm for 10-15 minutes to obtain the inner layer premix. The temperature is controlled at 40-60℃ throughout the process to prevent premature rupture or melting of the microcapsule wall material due to high temperatures.

[0025] Step S2: Preparation of the outer layer premix. Ethylene propylene diene monomer (EPDM) rubber grafted with maleic anhydride polymer and ethylene-octene copolymer are added to a Banbury mixer and mixed at 120-150℃ for 8-12 minutes to fully plasticize the rubber matrix and ensure uniform blending with POE. Then, the second type of stress-responsive fluorescent probe—silica core-shell nanoparticles, nano-silica aerogel, titanium dioxide, and antioxidant are added sequentially. The mixture is then continued to be mixed at 110-130℃ for 5-8 minutes to obtain the outer layer premix. When adding the core-shell nanoparticles, the temperature should be strictly controlled not to exceed 130℃ to prevent sintering of the silica shell or excessive volatilization of the quencher due to high temperatures.

[0026] Step S3: Co-extrusion granulation and coating molding. The inner layer premix obtained in step S1 and the outer layer premix obtained in step S2 are respectively fed into a twin-screw co-extrusion granulator for melt blending and granulation to form inner layer masterbatch and outer layer masterbatch. The twin-screw extruder preferably adopts a parallel co-rotating twin-screw structure with a length-to-diameter ratio of 40:1-48:1 and a screw speed of 200-400 rpm. The extrusion temperature is divided into five zones: zone 1 temperature is 140-160℃, zone 2 temperature is 170-190℃, zone 3 temperature is 190-210℃, zone 4 temperature is 200-220℃, and the die head temperature is 190-210℃. After granulation, the inner layer masterbatch and outer layer masterbatch are respectively air-cooled and conveyed to the silo for later use.

[0027] Step S4: Double-layer co-extrusion coating. The inner layer masterbatch and outer layer masterbatch obtained in step S3 are fed into the inner and outer layer extruders of a double-layer co-extrusion extruder, respectively. After melting and plasticizing, they are coated onto the metal substrate in one go through the same co-extrusion die to form the inner and outer layers. The coating temperature is controlled at 180-220℃, and the linear speed is 10-30m / min. Specifically, the temperatures of each section of the inner layer extruder are set as follows: feeding section 160-180℃, compression section 190-200℃, metering section 200-210℃, and die head 200-220℃; the temperatures of each section of the outer layer extruder are set as follows: feeding section 170-190℃, compression section 200-210℃, metering section 210-220℃, and die head 210-225℃. The design of the inner and outer flow channels in the co-extrusion die should ensure that the two layers of melt are uniform, concentric, and have a smooth interface between the layers, without waves or mixing.

[0028] Step S5: Cooling and Post-processing. The double-layered wire is cooled and shaped using water or air cooling, then pulled and wound to obtain the finished coated wire. It is preferable to use a multi-stage cooling water bath for gradual cooling, with the initial water temperature controlled at 60-80℃, the middle section at 40-50℃, and the final section at 10-20℃, to avoid excessive internal stress in the coated layer due to rapid cooling. After exiting the cooling water bath, the surface moisture is dried by a high-pressure blower, and then product information is printed on the coated surface using an online inkjet printer. Finally, the finished wire is neatly wound up using a tension-controlled winding machine and waterproof packaging is applied.

[0029] In the above preparation method, the temperature, rotation speed and time parameters of each step work together to ensure the integrity and dispersion uniformity of each component (especially fluorescent microcapsules and core-shell nanoparticles) during the processing, and to optimize the bonding strength and appearance quality of the interlayer interface. This is the key process control point to achieve the technical effect of the present invention.

[0030] This invention provides a non-destructive testing method for the aforementioned plastic-coated environmentally friendly wire. This method requires no specialized testing equipment, only a portable ultraviolet lamp (recommended wavelength 365nm). The specific testing steps are as follows: the operator holds the ultraviolet lamp and irradiates the surface of the wire to be inspected, observing the fluorescence response on the surface; based on the observed fluorescence color and distribution, the location of the damage layer can be determined.

[0031] When blue fluorescence is observed under ultraviolet light, it indicates that the outer layer is damaged (the inner layer remains intact). The blue fluorescence originates from the stress-activated luminescence of the second type of stress-responsive fluorescent probe in the outer layer—silica core-shell nanoparticles—indicating that the outer layer has been subjected to mechanical stress or scratches, resulting in cracks or gaps.

[0032] When red fluorescence is observed under ultraviolet light, it indicates that the inner layer has been damaged (the outer layer may be intact or the inner layer may be visible through the damage). The red fluorescence originates from the Rhodamine B dye released by the rupture of the first type of corrosion-inhibiting fluorescent microcapsules in the inner layer, indicating that a penetrating crack has occurred in the inner layer and that the corrosion inhibitor has been released to suppress corrosion of the metal substrate.

[0033] When both blue and red fluorescence are observed under ultraviolet light, it indicates that both the inner and outer layers have been damaged. This means that the overall protective function of the coating layer has been severely compromised, and the metal substrate is directly exposed. Repair or replacement of the wiring should be arranged immediately.

[0034] This method can quickly scan and inspect the entire cable (scanning speed can reach 2-5m / s), can be completed by a single person, is completely non-destructive, and can be flexibly implemented during the day or night, greatly reducing maintenance costs and downtime.

[0035] Compared with the prior art, the beneficial effects of the present invention are:

[0036] High weather resistance and strong adhesion: The inner layer adopts a hyperbranched polyester-fluorosilicone block copolymer system, utilizing the dense end groups of the hyperbranched structure to provide a strong interfacial bond with the metal substrate, while the low surface energy of the fluorosilicone blocks effectively blocks the penetration of corrosive media; the outer layer adopts an EPDM-g-MAH / POE elastomer system, which has outstanding weather resistance. Combined with the synergistic UV resistance of titanium dioxide and nano-aerogel, the chalking grade is 0 after 1000 hours of QUV accelerated aging, and the color difference ΔE < 2.0. Through the functional division of the two layers, the contradiction between "adhesion and weather resistance" in traditional single-layer materials is successfully solved.

[0037] In-situ, non-destructive, and layer-specific detection capabilities: By introducing "damage-release" fluorescent microcapsules (red fluorescence + corrosion inhibitor release) into the inner layer and "stress-activated" fluorescent core-shell nanoparticles (blue fluorescence + AIE effect) into the outer layer, a dual-wavelength, dual-response fluorescence system is constructed. This system can visually distinguish whether damage occurs in the inner layer, outer layer, or both layers through simple UV irradiation without disassembly or contact. It features fast response, high sensitivity, and eliminates the need for expensive testing instruments and professional operators, significantly improving maintenance efficiency and safety throughout the entire lifecycle of the wire.

[0038] Active corrosion protection: When the inner layer is damaged, the 8-hydroxyquinoline corrosion inhibitor released can chelate with metal ions at the damaged site, forming a protective complex layer in situ, effectively delaying the spread of local corrosion. This active corrosion inhibition mechanism provides a "self-repair window" after damage occurs, giving maintenance personnel time to detect and repair the damage, and avoiding sudden corrosion fracture accidents.

[0039] Active corrosion inhibition function: When the inner layer is damaged, the 8-hydroxyquinoline corrosion inhibitor released can chelate with metal ions at the damaged site, forming a protective complex layer in situ, effectively delaying the spread of local corrosion. This active corrosion inhibition mechanism is equivalent to providing a "self-repair window" after the damage occurs, giving maintenance personnel time to detect and repair, and avoiding sudden corrosion fracture accidents. The synergistic effect of hyperbranched polyester and HTPB toughening agent in the inner layer, as well as the contribution of EPDM / POE elastomer in the outer layer, enables the coated wire to maintain a certain stiffness while achieving an elongation at break of 300%-450%, no brittleness under low temperature (-40℃) impact, and an environmental stress cracking resistance time of over 500 hours. All mechanical properties are superior to traditional single-layer coated wire, and it can adapt to extreme environments such as severe cold, sandstorms, and high humidity. Detailed Implementation

[0040] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0041] This invention provides a high weather-resistant metal-coated polymer material and its preparation method.

[0042] This embodiment prepares a double-layer coated wire of high weather-resistant metal coated polymer material, which is intended for use as a gabion fence in cold outdoor regions.

[0043] 1. Raw material formula (by weight):

[0044] Inner layer: 50 parts hyperbranched polyester; 30 parts PVDF-b-PDMS; 10 parts of Class I corrosion-inhibiting fluorescent microcapsules (core material is 8-hydroxyquinoline:rhodamine B=4:1, wall material is polyurea resin, core-to-wall ratio is 1:3, particle size is 3μm); 10 parts HTPB (number average molecular weight 2800); 5 parts nano-hydrotalcite; 7702 parts light stabilizer.

[0045] Outer layer: 60 parts EPDM-g-MAH; 30 parts POE; 12 parts of type II stress-responsive fluorescent probe-silica core-shell nanoparticles (core is a TPE derivative, shell is hollow mesoporous SiO2, internally encapsulated with NBD-Cl quencher, core-shell mass ratio 8:1, particle size 120nm); 8 parts nano-silica aerogel; 5 parts titanium dioxide; 10101 parts antioxidant; 1680.5 parts antioxidant.

[0046] 2. Preparation process:

[0047] (1) Inner layer premixing: Weigh each component of the inner layer according to the formula. First, put the hyperbranched polyester, HTPB and fluorescent microcapsules into a low-speed mixer and mix at 300 rpm for 6 minutes. Then add PVDF-b-PDMS, nano-hydrotalcite and light stabilizer 770, increase the speed to 700 rpm and mix for 12 minutes. Cooling water is circulated through the jacket throughout the process to control the material temperature to not exceed 55℃. The material is then discharged for later use.

[0048] (2) Outer layer premixing: Weigh each component of the outer layer according to the formula, put EPDM-g-MAH and POE into a mixer, and mix at 135°C for 10 minutes; then add core-shell nanoparticles, nano silica aerogel, titanium dioxide, antioxidant 1010 and antioxidant 168 in sequence, lower the temperature of the mixing chamber to 120°C, and continue mixing for 6 minutes. Discharge and set aside.

[0049] (3) Co-extrusion granulation: The inner and outer premixes are fed into two parallel co-rotating twin-screw granulators (model SHJ-35B, Nanjing J&T Electromechanical Co., Ltd., length-to-diameter ratio 44:1). The temperatures of each section are set as follows: Zone 1 155℃, Zone 2 185℃, Zone 3 205℃, Zone 4 215℃, and die head 205℃. The screw speed is 300 rpm. After granulation, inner and outer masterbatches are obtained with a particle size of approximately 3 mm. The masterbatches are then screened to remove fine powder before use.

[0050] (4) Double-layer co-extrusion coating: Hot-dip galvanized aluminum-magnesium steel wire with a diameter of 2.5 mm (coating weight ≥ 300 g / m²) is selected as the metal wire. After the wire is fed by the wire feeder, it is first straightened by a straightener and then preheated to about 100°C by a medium-frequency induction heating device. The double-layer co-extrusion extruder adopts a flat die double-layer co-extrusion die. The inner extruder (screw diameter 45 mm) and the outer extruder (screw diameter 55 mm) plasticize their respective masterbatches. The temperature settings of the inner extruder are: feeding section 170°C, compression section 195°C, metering section 210°C, and die head 215°C; the temperature settings of the outer extruder are: feeding section 180°C, compression section 205°C, metering section 215°C, and die head 220°C. The temperature inside the co-extrusion die is set to 210°C. In the mold flow channel, the inner layer of melt first evenly coats the steel wire, and then the outer layer of melt covers the inner layer. The two layers are formed in one go at the mold exit. The linear velocity is controlled at 20m / min.

[0051] (5) Cooling and winding: The coated wire first enters a vacuum sizing and cooling water tank (3m long, first section vacuum degree -0.02MPa, water temperature 25℃; second section water tank 4m long, water temperature 15℃), and the plastic coating is completely cured after two stages of cooling. Then, the surface moisture is removed by a pneumatic blow dryer, the specifications and date are printed by an online inkjet printer, and finally, it is wound into a coil by a double-coil winding machine with a constant tension (50N), each coil weighing about 1000kg. The final product has a total plastic coating thickness of 0.60mm, with an inner layer thickness of 0.25mm and an outer layer thickness of 0.35mm, and a concentricity error of ≤0.05mm.

[0052] 3. Performance Testing:

[0053] (1) Adhesion test: The adhesion test was conducted according to the ISO4624:2002 pull-off method. A general-purpose epoxy adhesive was used to bond the surface of the plastic coating to an aluminum alloy ingot (d=20mm). The coating was stretched vertically at a rate of 1mm / min on a tensile testing machine. The test results showed that the adhesion between the plastic coating and the metal substrate in Example 1 was 7.2MPa, and the failure mode was cohesive failure (fracture occurred inside the plastic coating), indicating that the interfacial bonding strength was higher than the strength of the material itself, and the adhesion was excellent.

[0054] (2) Weather resistance test: Xenon lamp accelerated aging test was conducted according to GB / T16422.2-2014 (wavelength 295-800nm, irradiance 0.51W / m²@340nm, cycle: 102min light irradiation / 18min spray). After 1000 hours of testing, the surface of the plastic coating layer showed no chalking or cracking, the color difference ΔE=1.8 (<3.0), and the gloss retention rate was ≥85%. QUV aging was conducted according to GB / T1865-2009 for 1000 hours (UVA-340 lamp tube, cycle 8h light irradiation at 60℃ / 4h condensation at 50℃). The chalking level was 0, and the color difference ΔE=1.5.

[0055] (3) Low-temperature embrittlement test: Referring to GB / T5470-2008, the plastic coating was peeled off to make a standard sample (0.6 mm thick), placed in a -40℃ constant temperature chamber for 2 hours, and then tested on an impact testing machine. None of the samples in Example 1 cracked, and the fracture mode was ductile fracture. The elongation at break was still 220% at -40℃ (380% at room temperature), indicating that the material has excellent low-temperature resistance.

[0056] (4) Environmental stress cracking resistance (ESCR): According to GB / T1842-2008, the specimens were immersed in Igepal CO-630 solution (10% by volume) at 100°C and bending stress was applied, and the cracking time was recorded. The cracking time of the specimen in Example 1 was >550 hours (some specimens were still uncracked when the test was terminated), which was much longer than that of the control group.

[0057] (5) Verification of fluorescence self-diagnosis function: A section of the plastic-coated wire prepared in Example 1 was taken and its entire surface was irradiated in a dark room with a UV lamp (365nm, 6W). No fluorescence signal was observed (the background was dark purple). A scratch about 0.2mm deep (not penetrating to the inner layer) was made on the outer surface with a diamond scriber. The scratch was then irradiated, and a bright blue fluorescence was observed in the scratch area, which was visible to the naked eye, indicating that the outer layer was damaged. Next to the scratch, a penetrating scratch about 0.8mm deep was made (clearly touching the inner layer). The scratch was irradiated, and both blue and red fluorescence were observed in the scratch area (red fluorescence was seen to shine through from the depth direction), indicating that both the inner and outer layers were damaged. The test continued by applying local tension to the unscratched surface (by clamping and stretching about 5% strain). The stretched area showed diffuse blue fluorescence under a UV lamp, indicating that stress micro-damage occurred in the outer layer. The above verification results consistently demonstrate that the fluorescent self-diagnostic function of the coated wire of the present invention fully meets the design expectations and can reliably determine the location of the damaged layer through fluorescence color and position.

[0058] Example 2

[0059] The examples adjust the component ratio of the inner fluorescent microcapsules based on Example 1 to explore the effect of different core-to-wall ratios on detection sensitivity.

[0060] The inner layer formulation was adjusted to: 50 parts hyperbranched polyester; 30 parts PVDF-b-PDMS; 12 parts of type I corrosion-inhibiting fluorescent microcapsules (core material: 8-hydroxyquinoline: rhodamine B = 3:1 (mass ratio), wall material: polyurea resin, core-to-wall ratio 1:2, particle size 2 μm); the remaining components were the same as in Example 1. The outer layer formulation was the same as in Example 1.

[0061] The preparation process is basically the same as in Example 1, except that the low-speed mixing time during the inner layer premixing is extended to 8 minutes to ensure more uniform dispersion of microcapsules.

[0062] Performance test results: Adhesion 6.8MPa (still excellent); Weather resistance color difference ΔE=1.9; In terms of fluorescence sensitivity, for the same outer layer scratch, the blue fluorescence intensity is basically the same as in Example 1; for scratches penetrating the inner layer, the red fluorescence brightness is higher than in Example 1 (due to a larger core-to-wall ratio, more Rhodamine B is released), making it easier to visually identify. However, after long-term thermal aging (100℃×1000h), the red fluorescence decays somewhat (because the thinner wall material has a slightly weaker effect in delaying release). Overall, Example 2 shows an improvement in fluorescence sensitivity, but its long-term stability is slightly inferior to Example 1. Depending on the application scenario, Example 2 can be selected when higher sensitivity is desired; Example 1 should be used when long-term stability is desired.

[0063] Example 3

[0064] In this embodiment, the ratio of the outer core-shell nanoparticles is adjusted to optimize the tunability of the outer stress fluorescence response.

[0065] The outer layer formulation was adjusted to: 60 parts EPDM-g-MAH; 30 parts POE; 10 parts of type II stress-responsive fluorescent probe-silica core-shell nanoparticles (core-shell mass ratio 5:1, particle size 80nm); 10 parts nano-silica aerogel; 4 parts titanium dioxide; 10101 parts antioxidant; 1680.5 parts antioxidant. The inner layer formulation was the same as in Example 1.

[0066] Performance test results: The outer layer exhibits extremely high blue fluorescence sensitivity; even after scratching the wire surface with a fingernail, faint blue fluorescent lines can be observed under ultraviolet light, and the stress response threshold is significantly reduced. However, the tensile strength of the outer layer decreases slightly (from 18.5 MPa in Example 1 to 17.2 MPa), which is because the reduced proportion of the shell in the core-shell nanoparticles weakens the reinforcing effect of the silica shell. This approach is suitable for applications requiring extremely high detection capabilities for early damage (such as minor scratches).

[0067] Comparative Example 1 (Non-fluorescent system)

[0068] This comparative example aims to verify the influence of fluorescent components on the basic properties of the coated material. The formulation is basically the same as in Example 1, but the inner layer does not contain the first type of corrosion-inhibiting fluorescent microcapsules, and the outer layer does not contain the second type of stress-responsive fluorescent probe—silica core-shell nanoparticles. The missing parts are made up by the corresponding matrix resins (5 parts hyperbranched polyester and 5 parts PVDF-b-PDMS are added to the inner layer, and 6 parts EPDM-g-MAH and 6 parts POE are added to the outer layer). The preparation process is the same as in Example 1.

[0069] Performance test results: Adhesion 7.0 MPa (comparable to Example 1); Weather resistance color difference ΔE=2.0 (comparable); Low temperature toughness, ESCR and other indicators are basically the same as in Example 1. However, in the fluorescence detection test, no fluorescence signal was observed under UV light, making it impossible to determine the location of the damaged layer. This result indicates that the introduction of fluorescent components did not adversely affect the basic mechanical properties and aging resistance of the coated material; however, it lacked the crucial intelligent self-diagnostic function.

[0070] Comparative Example 2 (fluorescence only in the inner layer)

[0071] The inner layer formulation of this comparative example is the same as that of Example 1 (containing fluorescent microcapsules), and the outer layer formulation is the same as that of Comparative Example 1 (excluding core-shell nanoparticles). The preparation process is the same as above.

[0072] Performance test results: Adhesion 7.1 MPa; Weather resistance color difference ΔE=2.2; Under UV light irradiation, the outer surface showed no blue fluorescence response; When a scalpel was inserted deep into the outer layer and touched the inner layer, red fluorescence was observed seeping from the scratch. A single test could only confirm damage to the inner layer, but could not distinguish whether the outer layer was damaged independently (damage to the inner layer necessarily means damage to the outer layer as well, but damage to the outer layer alone cannot be detected). This comparative example can only detect damage to the inner layer, losing the ability to independently diagnose damage to the outer layer, and cannot meet the "layer location discrimination" objective of this invention.

[0073] Comparative Example 3 (fluorescence only in the outer layer)

[0074] The outer layer formulation of this comparative example is the same as that of Example 1 (containing core-shell nanoparticles), and the inner layer formulation is the same as that of Comparative Example 1 (excluding fluorescent microcapsules). The preparation process is the same as above.

[0075] Performance test results: Adhesion 7.0 MPa; Weather resistance color difference ΔE=1.9; Under UV light, scratches on the outer surface showed blue fluorescence, successfully detecting damage to the outer layer; however, when the scratches penetrated to the inner layer or even the metal substrate, because no fluorescent material was released from the inner layer, only blue fluorescence (from the outer layer) was visible under UV light, making it impossible to identify whether the inner layer was also damaged, or to determine whether the corrosion inhibitor had been released. This comparative example also lost the crucial ability of "layer location discrimination," being effective only for the damaged outer layer.

[0076] Comprehensive Test Comparison Table

[0077]

[0078] In summary, this invention, through the design of a "dual-layer, dual-response fluorescent system," achieves intelligent self-diagnostic capabilities for the coating layer, including in-situ, layer-specific discrimination, and location indication, while maintaining the material's high weather resistance, high adhesion, and high toughness. This represents a significant advancement and has extremely high industrial application value.

[0079] Without departing from the technical concept of this invention, those skilled in the art can adjust the components, proportions, and process parameters in the above embodiments, while still falling within the protection scope of this invention. For example:

[0080] In the inner layer, the hyperbranched polyester portion can be replaced with amino-terminated hyperbranched polyamide to improve its coordination ability with the metal substrate, but this may reduce the phase separation degree of the fluorosilicone block, which requires experimental verification.

[0081] In the outer layer, EPDM grafted maleic anhydride can be replaced with a mixture of chlorinated polyethylene (CPE) and polyolefin elastomer. This can reduce raw material costs while maintaining weather resistance. However, the chlorine content of CPE needs to be controlled at 30-40% to ensure compatibility with POE.

[0082] In the co-extrusion coating process, a two-stage vacuum shaping process (inner layer shaping followed by outer layer shaping) can be used instead of a one-time vacuum shaping process, which can further optimize the concentricity between layers, but will increase equipment investment and energy consumption.

[0083] For applications requiring long-term, high-intensity UV protection, a three-layer synergistic UV protection system can be formed by adding UV absorber UV-328 (0.1-0.3 parts) to the outer layer, along with nano-silica aerogel and titanium dioxide.

[0084] In fluorescence detection, a handheld ultraviolet lamp with a wavelength of 365nm or 395nm can be used. Under a 395nm lamp, the red fluorescence is brighter, but the blue fluorescence is relatively weaker. Different ultraviolet light sources can be selected according to the detection target. The dual-fluorescence system of this invention responds at both wavelengths, exhibiting a certain degree of flexibility and adaptability.

[0085] Although embodiments of the invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the invention, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A high weather-resistant metal-coated polymer material, characterized in that, The polymeric material is a double-layer plastic coating structure covering the outside of a metal substrate, including an inner layer in contact with the surface of the metal substrate and an outer layer covering the outside of the inner layer; The inner layer is made of the following components in parts by weight: 40-60 parts of hyperbranched polyester resin, 20-35 parts of fluorosilicone block copolymer, 5-15 parts of first-type corrosion-inhibiting fluorescent microcapsules, 8-12 parts of liquid polybutadiene toughening agent, 3-8 parts of nano-hydrotalcite, and 1-3 parts of hindered amine light stabilizer. The outer layer is made of the following components in parts by weight: 50-70 parts of EPDM-grafted maleic anhydride polymer, 25-40 parts of ethylene-octene copolymer, 8-18 parts of type II stress-responsive fluorescent probe-silica core-shell nanoparticles, 5-10 parts of nano-silica aerogel, 3-6 parts of titanium dioxide, and 1-2 parts of antioxidant. The core material of the first type of corrosion-inhibiting fluorescent microcapsule is a complex of 8-hydroxyquinoline and rhodamine B, and the wall material is polyurea resin; the core layer of the second type of stress-responsive fluorescent probe-silica core-shell nanoparticle is a mechanochromic molecule, the shell layer is hollow mesoporous silica, and a fluorescence quencher is encapsulated inside.

2. The high weather-resistant metal-coated polymer material according to claim 1, characterized in that, In the inner layer, the mass ratio of the core material to the wall material of the first type of corrosion-inhibiting fluorescent microcapsule is 1:2-1:4, and the particle size of the microcapsule is 1-5μm. In the outer layer, the particle size of the second type of stress-responsive fluorescent probe-silica core-shell nanoparticles is 50-200 nm, and the mass ratio of the mechanochromic molecule to the fluorescence quencher is 5:1-10:

1.

3. The high weather-resistant metal-coated polymer material according to claim 1 or 2, characterized in that: The hyperbranched polyester resin is a hydroxyl-terminated hyperbranched polyester with a number average molecular weight of 2000-5000; the fluorosilicone block copolymer is a polyvinylidene fluoride-polydimethylsiloxane block copolymer, wherein the degree of polymerization of the polyvinylidene fluoride block is 100-200 and the degree of polymerization of the polydimethylsiloxane block is 50-100.

4. A plastic-coated environmentally friendly wire, comprising a metal wire and a plastic coating layer covering the outside of the metal wire, characterized in that... The plastic coating layer is a double-layer structure composed of a high weather-resistant metal plastic coating polymer material according to any one of claims 1-3.

5. The plastic-coated environmentally friendly wire according to claim 4, characterized in that: The metal wire is a zinc-aluminum alloy wire, a zinc-aluminum-magnesium alloy wire, or a copper-clad steel wire. The total thickness of the plastic coating is 0.5-2.0 mm, of which the inner layer accounts for 40%-60% of the total thickness of the plastic coating.

6. A wire mesh product, characterized in that, It is woven or twisted from the plastic-coated environmentally friendly wire as described in claim 4 or 5.

7. A method for preparing a high weather-resistant metal-coated polymer material as described in any one of claims 1-3, characterized in that, Includes the following steps: (1) Preparation of inner layer premix: Hyperbranched polyester resin, liquid polybutadiene toughening agent and first type of corrosion-inhibiting fluorescent microcapsules are mixed in a low speed mixer at a speed of 200-400 rpm for 5-10 minutes. Then, fluorosilicone block copolymer, nano-hydrotalcite and hindered amine light stabilizer are added and mixed at a speed of 600-800 rpm for 10-15 minutes to obtain inner layer premix. The temperature is controlled at 40-60℃ throughout the process. (2) Preparation of outer layer premix: Ethylene propylene diene monomer (EPDM) grafted maleic anhydride polymer and ethylene-octene copolymer are put into a mixer and mixed at 120-150℃ for 8-12 minutes. Then, the second type of stress-responsive fluorescent probe-silica core-shell nanoparticles, nano silica aerogel, titanium dioxide and antioxidant are added in sequence. The temperature is maintained at 110-130℃ and the mixing continues for 5-8 minutes to obtain the outer layer premix. (3) Co-extrusion granulation and plastic molding: The inner layer premix obtained in step (1) and the outer layer premix obtained in step (2) are respectively fed into the twin-screw co-extrusion granulation unit for melt blending and granulation to form inner layer masterbatch and outer layer masterbatch. (4) Double-layer co-extrusion coating: The inner layer masterbatch and the outer layer masterbatch obtained in step (3) are respectively fed into the inner layer extruder and the outer layer extruder of the double-layer co-extrusion extruder. After melting and plasticizing, they are coated onto the outside of the metal substrate in one go through the same co-extrusion die to form the inner layer and the outer layer. The coating temperature is controlled at 180-220℃ and the linear speed is 10-30m / min. (5) Cooling and post-processing: The wire with double-layer structure is cooled and shaped by water cooling or air cooling, and then pulled and wound to obtain the finished plastic-coated wire.

8. The preparation method according to claim 7, characterized in that: In step (3), the twin-screw co-extrusion granulator adopts a parallel and co-directional twin-screw structure with a length-to-diameter ratio of 40:1-48:1, a screw speed of 200-400 rpm, and an extrusion temperature divided into five zones: zone 1 temperature is 140-160℃, zone 2 temperature is 170-190℃, zone 3 temperature is 190-210℃, zone 4 temperature is 200-220℃, and the die head temperature is 190-210℃.

9. A method for detecting damage to the plastic-coated environmentally friendly wire as described in claim 4 or 5, characterized in that, Includes the following steps: The surface of the plastic-coated environmentally friendly wire was irradiated with a portable ultraviolet lamp to observe its surface fluorescence response; When red fluorescence is observed under ultraviolet light, it indicates that the inner layer is damaged; When blue fluorescence is observed under ultraviolet light, it indicates that the outer layer is damaged; When both blue and red fluorescence are observed under ultraviolet light, it indicates that both the inner and outer layers are damaged.

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