Reinforced aluminized polyester film and preparation method thereof

Abstract

The reinforced aluminized polyester film comprises a polyester base material and a reinforced coating coated on at least one surface of the polyester base material, and the coating liquid of the reinforced coating comprises the following components in percentage by weight: 5-15% of polyester resin, 5-15% of polyester resin, 5-15% of polyester resin, 5-15% of polyester resin, 5-15% of polyester resin, 5-15% of polyester resin and the balance of 10%-20% of modified acrylic resin; 0.1%-5% of a cross-linking agent; 0.01%-1% of an auxiliary agent; and 59%-84.89% of deionized water. The modified acrylic resin in the reinforced coating coated by the polyester film is copolymerized by soft, hard and functional monomers, so that the aluminized polyester film can still keep good aluminum adhesive force under the harsh conditions that the temperature is 121 DEG C and the film is cooked for 40 minutes.

Description

Technical Field

[0001] This invention relates to an enhanced aluminized polyester film and its preparation method, belonging to the field of film technology. Background Technology

[0002] Polyester film is widely used in electronics, power, optical products, magnetic products, and packaging due to its excellent mechanical, optical, electrical insulation, barrier, temperature and chemical corrosion resistance, and good dimensional stability. In the packaging materials field, polyester film has advantages such as low water absorption, good water resistance, and suitability for packaging foods with high moisture content. However, polyester film itself has weak adhesion. Even with corona treatment to improve surface polarity, it still cannot meet the adhesion requirements of special coatings, such as non-solvent-based coatings. Especially under high temperature and high humidity conditions, the surface tension of polyester film decreases drastically, making it difficult to ensure that the aluminum plating layer will not peel off during processing.

[0003] Currently, the films developed to replace aluminum films mainly include aluminized films, CPP base films for alumina, and polyester films. Among them, polyester films have excellent high-temperature resistance and water resistance due to their semi-crystalline properties, but when further processed on their surface, such as aluminizing, silvering, or alumina plating, insufficient adhesion still exists. Although some manufacturers use offline coating pretreatment agents to enhance the interlayer adhesion between the vapor-deposited layers, the pretreatment layer is relatively thick, making it difficult to fully meet the requirements for boiling resistance and anti-adhesion, and its service life is limited. Furthermore, the film is prone to mechanical scratches during the coating process, affecting the product's appearance.

[0004] CN110790968A discloses an online-coated modified biaxially oriented polyester film, its preparation method, and its uses. This patent provides a modified biaxially oriented polyester film, which is coated on one or both sides of a polyester base film. The coating is an aqueous coating solution applied to the surface of the polyester base film and then dried by evaporation. The aqueous coating solution includes an aqueous resin, a curing agent, a surfactant, chitosan, and functional additives. The water-soluble resin is copolymerized from monomers such as vinylidene chloride, acrylic acid, alkyl (meth)acrylate, vinyl acetate, and cellulose acrylic acid. This film exhibits good barrier properties after aluminum plating, making it particularly suitable for use as a food packaging material. It also demonstrates high adhesion between the film and the aluminum layer, with a peel strength exceeding 8.7 N / 25 mm. However, this patent still has limitations, including the need for further optimization of the coating solution formulation to enhance the coating's water resistance and barrier properties, and the potential for mechanical scratches during the coating process that could affect the product's appearance. Summary of the Invention

[0005] To overcome the shortcomings of the prior art, this invention provides an enhanced aluminized polyester film and its preparation method. The modified acrylic resin in the reinforcing coating of the polyester film is copolymerized with soft, hard and functional monomers, so that the aluminized polyester film can still maintain good aluminum adhesion under the harsh conditions of 121°C and boiling for 40 minutes.

[0006] The technical solution adopted by this invention to solve its technical problem is: A reinforced aluminized polyester film, the polyester film comprising a polyester substrate and a reinforcing coating applied to at least one side of the polyester substrate, the reinforcing coating liquid comprising the following components in weight percentages: Polyester resin: 5%-15%; Modified acrylic resin: 10%-20%; Crosslinking agent: 0.1%-5%; Additives: 0.01%-1%; Deionized water: 59%-84.89%.

[0007] The modified acrylic resin in the above-mentioned reinforced aluminized polyester film is copolymerized from soft monomers, hard monomers and functional monomers.

[0008] In the aforementioned reinforced aluminized polyester film, the soft monomer is one or more of ethyl acrylate, butyl acrylate, or octyl acrylate in any weight ratio; the hard monomer is one or more of methyl methacrylate or styrene in any weight ratio; and the functional monomer is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, or phosphate methacrylate in any weight ratio.

[0009] The modified acrylic resin in the above-mentioned reinforced aluminized polyester film is copolymerized from the following monomers under an initiator: 10-15 parts acrylic acid; 10-15 parts ethyl acrylate; 10-15 parts of methyl methacrylate; 5-10 parts of hydroxyethyl acrylate; Phosphate methacrylate 1-5 parts.

[0010] In the above-mentioned reinforced aluminized polyester film, the crosslinking agent is one of oxazoline, isocyanate, pyridine, or melamine; the auxiliary agent is an acetylenic diol auxiliary agent or an organosilicon auxiliary agent.

[0011] The aforementioned reinforced aluminized polyester film contains two types of particles with different particle sizes on the surface of the polyester substrate, namely 1μm~2μm and 3μm~4μm; the ratio of the particle sizes is 1:1~2:1.

[0012] The aforementioned reinforced aluminized polyester film contains silica particles in its surface layer. These particles are spherical in shape and have a total content of 500ppm-2000ppm.

[0013] The thickness of the reinforcing coating in the above-mentioned reinforced aluminized polyester film is 10nm to 80nm; the thickness of the polyester substrate is 8μm to 25μm.

[0014] A method for preparing an enhanced aluminized polyester film, the method comprising the following steps: a. Feed the polyester substrate raw material into the extrusion system to melt and extrude the substrate melt; b. Forming the substrate melt into an amorphous cast sheet on a cooling roller; c. After the cooled cast plastic sheet is preheated, it is stretched longitudinally by 3.0 to 5.0 times to obtain a film; d. Apply the coating liquid for reinforcing the coating onto one side of the above-mentioned film; e. After preheating, the film coated with the reinforcing coating solution is stretched laterally by 3.0 to 5.0 times to obtain a thin film; f. Heat-set the film to obtain a reinforced aluminized polyester film.

[0015] In the above-mentioned method for preparing reinforced aluminized polyester film, the preheating temperature in step c is 60℃-80℃; the preheating temperature in step e is 100℃-120℃; and the heat setting temperature in step f is 220℃-240℃.

[0016] The beneficial effects of this invention are: 1. This invention significantly improves the adhesion of polyester film to aluminum, especially to vacuum-metallized layers, by coating a special adhesion-enhancing coating on the surface of a 12μm-25μm PET film, effectively solving the problem of insufficient adhesion of polyester film in the prior art.

[0017] 2. The reinforced coating of this invention is composed of solvent water, waterborne polyester resin, waterborne modified acrylic resin, waterborne crosslinking agent, and additives, forming a dense and uniform coating structure that effectively improves the coating's water resistance and barrier properties. The waterborne modified acrylic resin, through the copolymerization design of soft, hard, and functional monomers, provides excellent flexibility, hardness, and adhesion to the aluminum plating layer. On one hand, by designing the carboxyl and hydroxyl functional groups in the modified acrylic resin to react with the crosslinking agent, strong covalent bonds are formed, greatly increasing the crosslinking density. The higher the crosslinking density, the tighter the coating network structure, and the more difficult it is for water molecules to penetrate and swell the coating. On the other hand, the synergistic effect of the soft monomers, hard monomers, and functional monomers makes the coating both hard and tough, preventing brittle fracture. By precisely proportioning monomers, the rigidity and flexibility of the coating are cleverly balanced. Through multifunctional crosslinking and special chemical bonding, a protective system that can maintain structural integrity and strong adhesion under high temperature and high humidity conditions is constructed. This allows the final reinforced aluminized polyester film to easily pass the rigorous boiling test at 121°C for 40 minutes, and it has excellent boiling resistance and anti-blocking properties, meeting the requirements of special application scenarios such as high-end packaging.

[0018] 3. The present invention employs an online coating surface treatment process and a structural design of large and small silica particles on the surface, which improves the surface roughness and affinity of the polyester film, providing a good surface foundation for subsequent coating of reinforcing coatings; 4. This invention uses an online coating process to simultaneously stretch the reinforcing coating and the polyester film laterally by 3-5 times, forming a good interfacial bond with the substrate, thus avoiding the problems of thick coating and easy peeling of traditional pretreatment layers. 5. The coating of the present invention adopts a water-based system formulation, which has good environmental protection and non-toxicity, and meets the requirements of green environmental protection. Attached Figure Description

[0019] Figure 1 A schematic diagram of the structure of the aluminized polyester film.

[0020] In the diagram: 1. Polyester substrate; 2. Reinforcing coating. Detailed Implementation

[0021] The present invention involves coating at least one side of a polyester substrate with a reinforcing coating, wherein the modified acrylic resin in the coating liquid is selected as a copolymer of soft monomers, hard monomers and functional monomers.

[0022] The soft monomer is one or more of ethyl acrylate, butyl acrylate, or octyl acrylate in any weight ratio; the soft monomer provides flexibility and has the function of absorbing and releasing thermal stress, preventing the coating from cracking or peeling off from the substrate due to stress concentration.

[0023] The hard monomer is one or more of methyl methacrylate or styrene in any weight ratio; the hard monomer provides rigidity, imparts dimensional stability and creep resistance to the coating at high temperatures, and prevents softening and deformation.

[0024] The functional monomers are one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, or phosphate methacrylate in any weight ratio. The modified acrylic resin functional monomers form a high-crosslink density network, better blocking water vapor penetration and improving chemical stability. Acrylic acid and methacrylic acid monomers provide carboxyl groups, which react with crosslinking agents (such as oxazoline, isocyanate, and melamine). Hydroxyethyl acrylate and hydroxypropyl acrylate monomers provide hydroxyl groups. As highly reactive groups, hydroxyl groups further increase crosslinking points and work synergistically with carboxyl groups. The crosslinking points of carboxyl groups are mainly concentrated near the polymer backbone, while the crosslinking points of hydroxyl groups are distributed in the three-dimensional space extending from the side chains. This multi-level crosslinking from the backbone to the side chain space makes the formed network more uniform and dense, effectively reducing microscopic defects caused by uneven distribution of crosslinking points, effectively increasing the pathways for water molecule penetration, and making the crosslinked network more complete and stable. This synergistic effect of multiple functional groups ensures that the coating will not collapse entirely due to partial bond breakage under cooking conditions. The formation of strong covalent bonds (such as ester and amide bonds) greatly increases the crosslinking density. Higher crosslinking density results in a denser network structure in the coating, making it more difficult for water molecules to penetrate and swell. Phosphate ester methacrylate monomers exhibit extremely strong chemical bonding and complexation with the aluminum metal surface, forming aluminum phosphate chemical bonds that are much stronger than those formed by physical adsorption and ordinary van der Waals forces. Even under the impact of high-temperature moisture, these chemical bonds remain extremely stable, effectively preventing the aluminum layer from "lifting off" or blistering from the coating surface. The double bonds they contain participate in copolymerization, while the phosphate groups may also participate in partial crosslinking reactions, further enhancing the coating's density.

[0025] This invention utilizes the synergistic effect of soft monomers, hard monomers, and functional monomers to create a reinforced coating that is both hard and tough, preventing brittle fracture. Through precise monomer formulation, the rigidity and flexibility of the coating are cleverly balanced. Furthermore, through multifunctional crosslinking and special chemical bonding, a protective system is constructed that maintains structural integrity and strong adhesion even under high temperature and high humidity conditions. This allows the final reinforced aluminized polyester film to easily pass a rigorous 121°C, 40-minute boiling test, exhibiting excellent boiling resistance and anti-blocking properties, meeting the requirements of special applications such as high-end packaging.

[0026] This invention enhances the coating by using both polyester resin and modified acrylic resin, resulting in a more uniform coating. Both polyester resin and modified acrylic resin contain polar ester groups (-COO-) in their molecular structures. This structural similarity endows them with a certain degree of thermodynamic compatibility. During the coating film formation process, as moisture evaporates, the particles of the two polymers deform and fuse. Their molecular chain segments diffuse and permeate into each other at the interface, forming physical entanglements. This entanglement provides effective mechanical strength. At the interface between the two resins, moderately strong hydrogen bonds can form between the -COOH group of acrylic acid and the C=O group of polyester; simultaneously, hydrogen bonds can also form between the -OH groups of the two resins and between -OH and C=O. Hydrogen bonds, as a strong secondary bond, can significantly improve the bonding force at the interface between the two resins, reduce phase separation, and make the composite coating more uniform.

[0027] The polyester substrate of this invention contains silica particles of two different particle sizes on its surface, with a total silica particle content of 500ppm-2000ppm. The silica particles are selected from two different particle sizes: 1μm-2μm and 3μm-4μm, with a particle size ratio of 1:1 to 2:1. During the heating and cooling cycles of cooking, the film expands and contracts. If the film surface is completely smooth, the resulting thermal stress will act uniformly on the entire aluminized layer and coating interface. If the coating adhesion is weak, it will lead to large-area and irreversible peeling. The dual-size particles form a complex microstructure on the PET surface. When the coating is applied, it flows into these uneven structures, forming a strong "mechanical interlocking" effect after curing. The combination of large and small particles creates a multi-layered roughness from the nanometer to the micrometer scale, providing more, deeper, and more stable anchoring points for the coating. This mechanical anchoring complements the chemical bonding (such as hydrogen bonds and ester bonds) between the coating and the substrate, together forming a dual guarantee against moisture penetration and thermal stress peeling.

[0028] The present invention will be further described below with reference to the embodiments. Example 1

[0029] Preparation of the coating solution for enhancing the coating: Take 5g of water-based polyester MD2000 (Toyobo), 10g of modified acrylic resin, 84.89g of deionized water, 0.1g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.01g of acetylation diol additive (BASF). Disperse them evenly using a high-shear emulsifier to prepare an enhanced coating liquid.

[0030] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 10 parts acrylic acid; 10 parts ethyl acrylate; 10 parts of methyl methacrylate; 5 parts hydroxyethyl acrylate; One part of phosphate methacrylate.

[0031] Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are preheated at 60°C and stretched longitudinally at a longitudinal stretch ratio of 3. The prepared reinforcing coating solution is applied to one side of the longitudinally stretched film using a gravure coating method. The film coated with the reinforcing coating solution is dried at 100°C and then stretched transversely by 3 times. Finally, it is heat-set and wound at 220°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 20nm.

[0032] The surface layer of the polyester substrate contains silica particles with a large particle size of 3 μm and a small particle size of 1 μm; the ratio of large to small particles is 1:1, and the content is 500 ppm. Example 2

[0033] Preparation of the coating solution for enhancing the coating: Take 15g of water-based polyester MD2000 (Toyobo), 20g of modified acrylate resin, 59g of deionized water, 5g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 1g of acetylation diol additive (BASF). Disperse them evenly using a high-shear emulsifier to prepare an enhanced coating liquid.

[0034] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 15 parts acrylic acid; 15 parts ethyl acrylate; 15 parts of methyl methacrylate; 10 parts of hydroxyethyl acrylate; Five parts of phosphate methacrylate.

[0035] Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are preheated at 80°C and stretched longitudinally at a longitudinal stretch ratio of 3. The prepared reinforcing coating solution is applied to one side of the longitudinally stretched film using a wire rod coating method. The film coated with the reinforcing coating solution is dried at 120°C and then stretched transversely by 3 times. Finally, it is heat-set and wound at 240°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 80nm.

[0036] The surface layer of the polyester substrate contains silica particles with a large particle size of 4 μm and a small particle size of 2 μm; the ratio of large to small particles is 2:1, and the content is 2000 ppm. Example 3

[0037] Preparation of the coating solution for enhancing the coating: Take 10g of water-based polyester MD2000 (Toyobo), 15g of modified acrylate resin, 72g of deionized water, 2.5g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.5g of acetylenic diol auxiliaries (BASF). Disperse them evenly using a high-shear emulsifier to prepare an enhanced coating solution.

[0038] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 12 parts acrylic acid; 12 parts ethyl acrylate; 12 parts of methyl methacrylate; 8 parts of hydroxyethyl acrylate; Three parts of phosphate methacrylate.

[0039] Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are preheated at 70°C and stretched longitudinally at a longitudinal stretch ratio of 3. The prepared reinforcing coating solution is applied to both sides of the longitudinally stretched film by dip coating. The film coated with the reinforcing coating solution is dried at 110°C and then stretched transversely by 3 times. Finally, it is heat-set and wound at 230°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 50nm.

[0040] The surface layer of the polyester substrate contains silica with a large particle size of 3.5 μm and a small particle size of 1.5 μm; the ratio of large to small particles is 1.5:1, and the content is 1250 ppm. Example 4

[0041] Preparation of the coating solution for enhancing the coating: Take 8g of water-based polyester MD2000 (Toyobo), 12g of modified acrylate resin, 76.25g of deionized water, 1.5g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.25g of acetylation diol additive (BASF). Disperse them evenly using a high-shear emulsifier to prepare an enhanced coating solution.

[0042] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 11 parts acrylic acid; 11 parts ethyl acrylate; 11 parts of methyl methacrylate; 7 parts hydroxyethyl acrylate; Two parts of phosphate methacrylate.

[0043] Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are preheated at 65°C and stretched longitudinally at a longitudinal stretch ratio of 3. The prepared reinforcing coating solution is applied to one side of the longitudinally stretched film using one of the gravure coating methods. The film coated with the reinforcing coating solution is dried at 105°C and then stretched transversely by 3 times. Finally, it is heat-set and wound up at 225°C to obtain a reinforced aluminized polyester film with a coating thickness of 35nm.

[0044] The surface layer of the polyester substrate contains silica particles with a large particle size of 3.3 μm and a small particle size of 1.3 μm; the ratio of large to small particles is 1.2:1, and the content is 800 ppm. Example 5

[0045] Preparation of the coating solution for enhancing the coating: Take 12g of water-based polyester MD2000 (Toyobo), 18g of modified acrylate resin, 65.75g of deionized water, 3.5g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.75g of acetylation diol additive (BASF). Disperse them evenly using a high-shear emulsifier to prepare an enhanced coating solution.

[0046] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 14 parts acrylic acid; 14 parts ethyl acrylate; 14 parts of methyl methacrylate; 9 parts of hydroxyethyl acrylate; 4 parts of phosphate methacrylate; Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are then preheated at 75°C and stretched longitudinally at a ratio of 3. The prepared reinforcing coating solution is then applied to one side of the longitudinally stretched film using a wire rod coating method. The film coated with the reinforcing coating solution is dried at 115°C and stretched transversely by 3 times. Finally, it is heat-set and wound at 235°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 65 nm.

[0047] The surface layer of the polyester substrate contains silica with a large particle size of 3.8 μm and a small particle size of 1.8 μm; the ratio of large to small particles is 1.8:1, and the content is 1600 ppm. Comparative Example 1

[0048] Preparation of the coating solution for enhancing the coating: Take 5g of water-based polyester MD2000 (Toyobo), 94.9g of deionized water, 0.1g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.01g of acetylation diol auxiliaries (BASF). Disperse them evenly using a high-shear emulsifier to prepare a reinforcing coating solution.

[0049] First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are preheated at 60°C and stretched longitudinally at a longitudinal stretch ratio of 3. The prepared reinforcing coating solution is applied to one side of the longitudinally stretched film using a gravure coating method. The film coated with the reinforcing coating solution is dried at 100°C and then stretched transversely by 3 times. Finally, it is heat-set and wound at 220°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 20nm.

[0050] The surface layer of the polyester substrate contains silica particles with a large particle size of 3 μm and a small particle size of 1 μm; the ratio of large to small particles is 1:1, and the content is 500 ppm. Comparative Example 2

[0051] Preparation of the coating solution for enhancing the coating: 18g of modified propylene resin, 65.75g of deionized water, 3.5g of oxazoline crosslinking agent WS-700 (Yuen Chemical), and 0.75g of acetylation diol additive (BASF) were dispersed evenly using a high-shear emulsifier to prepare an enhanced coating solution.

[0052] Waterborne acrylic resins are copolymerized from the following monomers under ammonium persulfate: 14 parts acrylic acid; 14 parts ethyl acrylate; 14 parts of methyl methacrylate; 9 parts of hydroxyethyl acrylate; Four parts of phosphate methacrylate.

[0053] Preparation of reinforced aluminized polyester film: First, the crystallized and dried Hefei Lucky 230 polyester chips are fed into the corresponding extrusion system for melt extrusion and cast onto a rotating cooling roller. The cooled cast sheets are then preheated at 75°C and stretched longitudinally at a ratio of 3. The prepared reinforcing coating solution is then applied to one side of the longitudinally stretched film using a wire rod coating method. The film coated with the reinforcing coating solution is dried at 115°C and stretched transversely by 3 times. Finally, it is heat-set and wound at 235°C to obtain a reinforced aluminized polyester film with a dry coating thickness of 65 nm.

[0054] The surface layer of the polyester substrate contains silica with a large particle size of 3.8 μm and a small particle size of 1.8 μm; the ratio of large to small particles is 1.8:1, and the content is 1600 ppm.

[0055] The performance testing methods are as follows: (1) Peel strength: Refer to QB / T 2358-1998 "Test method for heat sealing strength of plastic film packaging bags", heat seal the heat sealing layer of EAA film with the aluminum coating layer, heat sealing temperature 125℃, pressure 0.25MPa, heat sealing time 1.8s, and then use a tensile testing machine to peel the aluminum coating layer off the aluminum coating film to obtain peel strength data.

[0056] (2) Coating appearance quality: visually inspected under a strong flashlight. The coating appearance evaluation level is divided into 3 categories: ○ is judged as having no defects such as mottled appearance, longitudinal lines or bubble spots; △ is judged as having slight mottled appearance, longitudinal lines or bubble spots; and × is judged as having severe mottled appearance, longitudinal lines or bubble spots.

[0057] (3) Barrier properties: Referring to ASTM D-3985 and ASTM F-1249, the oxygen permeability and water vapor permeability of the reinforced aluminized polyester film after aluminization were tested, and the results are shown in Table 1.

[0058] The test results are shown in Table 1:

[0059] As can be seen from the comparison between Comparative Example 1 and Example 1, Example 1 uses both modified acrylic resin and waterborne polyester resin. Compared with the coating liquid without the addition of modified acrylic resin, the reinforced coating has better peel strength and better coating appearance after online coating and biaxial stretching.

[0060] Comparing Comparative Example 2 with Example 5, it can be seen that Example 5, which uses both modified acrylic resin and waterborne polyester, exhibits better peel strength and a better coating appearance after online coating and biaxial stretching compared to the coating solution without added polyester resin. Because the polyester resin has a similar chemical structure to the main body of the polyester film, it possesses affinity and excellent compatibility, enabling it to quickly and uniformly wet the surface of the polyester film, creating a compatible transition layer for the acrylic resin and forming co-crystallization and chain segment entanglement. During the heat setting stage of biaxial stretching, the molecular segments of the polyester resin and the molecular segments of the polyester film surface undergo interdiffusion and co-crystallization, forming a strong "anchoring layer." The core function of the waterborne polyester resin is to act as a "molecular bridge" and a "high-performance primer." Through these two powerful mechanisms—chemical similarity and compatibility, and thermally induced co-crystallization—it solves the problem of insufficient inherent adhesion between the acrylic resin and the polyester film substrate.

[0061] Furthermore, the addition of polyester resin is equivalent to implanting a large number of internal cross-linking points into the acrylic network. This not only increases the overall cross-linking density but also forms more cross-linking pathways. Even if a chemical bond breaks under cooking conditions, other bonds around it still support the network structure, greatly improving the durability and reliability of the coating. The composite of polyester and modified acrylic resin results in a coating that is both hard and wear-resistant, yet not so brittle as to develop microcracks during biaxial tensile deformation or subsequent processing. This optimized mechanical property also ensures that the coating remains intact in harsh processing and application environments, and the integrity of the coating is a prerequisite for its high adhesion and high barrier properties.

[0062] As can be seen from Table 1, the reinforced coating prepared in the embodiments of the present invention has significantly improved peel strength and coating appearance compared with the coating prepared in the comparative example. This indicates that the reinforced aluminized polyester film of the present invention not only has excellent peel strength performance, but also excellent resistance to boiling and barrier properties, and has good application prospects.

[0063] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. 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.

Claims

1. A reinforced aluminized polyester film, characterized in that: The polyester film comprises a polyester substrate (1) and a reinforcing coating (2) coated on at least one side of the polyester substrate (1), wherein the coating liquid of the reinforcing coating (2) comprises the following components in weight percentages: Polyester resin: 5%-15%; Modified acrylic resin: 10%-20%; Crosslinking agent: 0.1%-5%; Additives: 0.01%-1%; Deionized water: 59%-84.89%.

2. The reinforced aluminized polyester film according to claim 1, characterized in that: The modified acrylic resin is copolymerized from soft monomers, hard monomers and functional monomers.

3. The reinforced aluminized polyester film according to claim 2, characterized in that: The soft monomer is one or more of ethyl acrylate, butyl acrylate, or octyl acrylate in any weight ratio; the hard monomer is one or more of methyl methacrylate or styrene in any weight ratio; the functional monomer is one or more of acrylic acid, methacrylic acid, hydroxyethyl acrylate, hydroxypropyl acrylate, or phosphate methacrylate in any weight ratio.

4. The reinforced aluminized polyester film according to claim 3, characterized in that: The modified acrylic resin is copolymerized from the following monomers under an initiator: 10-15 parts acrylic acid; 10-15 parts ethyl acrylate; 10-15 parts of methyl methacrylate; 5-10 parts of hydroxyethyl acrylate; Phosphate methacrylate 1-5 parts.

5. The reinforced aluminized polyester film according to claim 1, characterized in that: The crosslinking agent is one of oxazoline, isocyanate, pyridine, or melamine; the auxiliary agent is an acetylenic diol or organosilicon auxiliary agent.

6. The reinforced aluminized polyester film according to claim 1, characterized in that: The surface layer of the polyester substrate (1) contains particles of two different sizes, with particle sizes of 1μm~2μm and 3μm~4μm respectively; the ratio of the size particles is 1:1~2:

1.

7. The reinforced aluminized polyester film according to claim 6, characterized in that: The surface particles are silica particles, which are spherical in shape and have a total content of 500ppm-2000ppm.

8. The reinforced aluminized polyester film according to claim 1, characterized in that: The thickness of the reinforcing coating is 10 nm to 80 nm; the thickness of the polyester substrate is 8 μm to 25 μm.

9. A method for preparing a reinforced aluminized polyester film as described in any one of claims 1-8, characterized in that: The preparation method includes the following steps: a. Feed the polyester substrate raw material into the extrusion system to melt and extrude the substrate melt; b. Forming the substrate melt into an amorphous cast sheet on a cooling roller; c. After the cooled cast plastic sheet is preheated, it is stretched longitudinally by 3.0 to 5.0 times to obtain a film; d. Apply the coating liquid for reinforcing the coating onto one side of the above-mentioned film; e. After preheating, the film coated with the reinforcing coating solution is stretched laterally by 3.0 to 5.0 times to obtain a thin film; f. Heat-set the film to obtain a reinforced aluminized polyester film.

10. The method for preparing the reinforced aluminized polyester film according to claim 9, characterized in that: In step c, the preheating temperature is 60℃-80℃; in step e, the preheating temperature is 100℃-120℃; and in step f, the heat setting temperature is 220℃-240℃.

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