Protective film, toughenable low-e glass and method for making same, low-e glass

Abstract

The application discloses a protective film, a steelable LOW-E glass and a preparation method and LOW-E glass thereof, and relates to the technical field of tempered glass, wherein the preparation raw material of the protective film comprises acrylate resin, acrylate monomer and photoinitiator; the acrylate resin comprises base resin and adjusting resin; the base resin comprises aliphatic urethane-acrylate oligomer; and the adjusting resin comprises at least one of terminal hydroxyl polybutadiene diacrylate, polybutadiene dimethacrylate and aromatic polyurethane acrylate. The protective film, the steelable LOW-E glass and the preparation method and LOW-E glass thereof provided by the application utilize the protective film with high hardness and compactness to protect the steelable LOW-E glass, and solve the technical problems of insufficient mechanical damage resistance and storage time of the steelable LOW-E glass.

Description

Technical Field

[0001] This invention relates to the field of tempered glass technology, and particularly to protective films, temperable LOW-E glass and their preparation methods, and LOW-E glass. Background Technology

[0002] Low-E glass is a key material in the field of building energy conservation. It is produced by tempering and then cooling temperable low-E glass. Temperable low-E glass has a silver-containing metal layer, a dielectric layer, and a protective layer deposited on its surface. The silver-containing metal layer effectively reflects infrared radiation, thereby achieving energy conservation.

[0003] However, the hardness of the silver-containing metal layer is only about 5B (pencil hardness test), far lower than the 5-6H of the glass substrate. The hardness of the dielectric and protective layers is also low, resulting in insufficient surface hardness of temperable LOW-E glass. During the pre-tempering processing, temperable LOW-E glass undergoes cutting, edge grinding, cleaning, transfer, and storage. Physical contact during this process, such as friction from cutting wheels and pressure from brushes, easily causes scratches or even breakage, making it difficult for the dielectric and protective layers to effectively protect the silver-containing metal layer. Simultaneously, the silver-containing metal layer is highly susceptible to oxidation in humid air, and the existing dielectric and protective layers lack sufficient density to effectively prevent oxygen and moisture from penetrating into the silver-containing metal layer, leading to oxidation, deterioration, performance degradation, and shortened storage time.

[0004] In summary, temperable LOW-E glass faces technical challenges due to insufficient hardness and density, and there is an urgent need for a protective film that combines high hardness and high density to provide effective protection for temperable LOW-E glass. Summary of the Invention

[0005] The main objective of this invention is to propose a protective film, temperable LOW-E glass, and a method for preparing the same. The invention utilizes a protective film with both high hardness and density to protect the temperable LOW-E glass, thereby solving the technical problems of insufficient resistance to mechanical damage and insufficient storage time of the temperable LOW-E glass.

[0006] To achieve the above objectives, the present invention proposes a protective film, wherein the raw materials for preparing the protective film include acrylate resin, acrylate monomer and photoinitiator; The acrylate resin includes a base resin and a conditioning resin; The base resin includes aliphatic urethane-acrylate oligomers; The conditioning resin includes at least one of hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate.

[0007] In one embodiment, the properties of the aliphatic urethane-acrylate oligomer satisfy at least one of the following conditions: (1) Viscosity is 1000-3000 mPa·s; (2) Solid content ≥ 99 wt%; (3) The initial decomposition temperature is 280-500℃; (4) The rate of change of viscosity within 72 hours is ≤ ±5%; (5) Glass transition temperature Tg < 80℃.

[0008] In one embodiment, the glass transition temperature Tg of the hydroxyl-terminated polybutadiene diacrylate is < 80°C; And / or, the glass transition temperature Tg of the polybutadiene dimethacrylate is < 80°C; And / or, the glass transition temperature Tg of the aromatic polyurethane acrylate is < 80°C.

[0009] In one embodiment, the mass ratio of the base resin to the conditioning resin is (9-10):1; And / or, the conditioning resin includes hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate; The mass mixing ratio of the hydroxyl-terminated polybutadiene diacrylate, the polybutadiene dimethacrylate, and the aromatic polyurethane acrylate is (0.5-1):(0.5-1):1.

[0010] In one embodiment, the acrylate resin is present in the raw materials for preparing the protective film at a content of 50-70 wt%. And / or, the acrylate monomer is present in the raw materials for preparing the protective film at a content of 25-49 wt%; And / or, the photoinitiator is present in the raw materials for preparing the protective film at a content of 1-5 wt%.

[0011] The present invention also proposes a temperable LOW-E glass, the temperable LOW-E glass comprising a LOW-E glass sheet and a protective film as described above located on the surface of the LOW-E glass sheet; The LOW-E glass substrate includes a glass substrate and a functional coating disposed on the surface of the glass substrate; The functional coating comprises, from the inside out, a functional layer and a protective layer; The functional layer includes n+1 dielectric layers and n silver-containing metal layers, wherein the dielectric layers and the silver-containing metal layers are alternately stacked from the inside to the outside, and the silver-containing metal layers are located between two adjacent dielectric layers, and n≥1; The protective layer is located on the outermost side of the functional coating.

[0012] In one embodiment, the hardness of the temperable LOW-E glass is ≥6H; And / or, the surface friction coefficient of the temperable LOW-E glass is <0.3; And / or, the surface porosity of the temperable LOW-E glass is ≤0.2%; And / or, the oxygen transmittance of the temperable LOW-E glass is <0.1 cm. 3 ·μm / (m 2 (day MPa); And / or, the water vapor transmission rate of the temperable LOW-E glass is <0.5 g / (m²). 2 ·day); And / or, the adhesion between the protective film and the original LOW-E glass in the temperable LOW-E glass is ≥90%; And / or, the residual carbon content of the protective film in the temperable LOW-E glass is <0.1wt% at a tempering temperature of 550-720°C.

[0013] In one embodiment, a method for preparing temperable LOW-E glass includes the following steps: A. Weigh the protective film raw materials according to the above composition and mix them to obtain the protective film coating; B. Apply the protective coating to the surface of the LOW-E glass substrate, and after UV curing, form a protective film to obtain the temperable LOW-E glass as described above.

[0014] In one embodiment, step B further includes cutting, edge grinding, and cleaning the temperable LOW-E glass, wherein the size of the cleaned glass deviates from the finished LOW-E glass size by ≤ ±0.5 mm.

[0015] The present invention also proposes a LOW-E glass, which is prepared by tempering and cooling the above-mentioned temperable LOW-E glass.

[0016] The technical solution of this invention uses an aliphatic urethane-acrylate oligomer as the base resin. The urethane bonds in its molecular structure endow the protective film with excellent flexibility and elastic recovery. When subjected to external forces such as friction from a cutting wheel or pressure from a brush, it can effectively buffer stress concentration through the elastic deformation of the molecular chain segments, reducing the risk of scratches on the film surface. At the same time, the aliphatic structure on the main chain of this oligomer avoids the rigid brittleness tendency caused by aromatic groups, further enhancing the impact toughness of the protective film. On this basis, adjusting the hydroxyl-terminated polybutadiene diacrylate and polybutadiene dimethacrylate in the resin to contain long-chain polybutadiene soft segments can increase the length of the flexible chain segments in the crosslinking network, giving the protective film higher elongation at break and tear strength, making the protective film less prone to microcracks when subjected to repeated friction. The aromatic polyurethane acrylate, due to its rigid benzene ring structure, forms hard segment microregions in the system, improving the surface hardness and scratch resistance of the protective film through microphase separation structure. The proper combination of soft and hard segments allows the protective film to maintain flexibility while possessing sufficient surface hardness, effectively resisting mechanical damage during the pre-tempering processing stage, thus protecting the silver-containing metal layer.

[0017] This technical solution enhances the density of the protective film by designing the molecular structure of acrylate resin and constructing a cross-linked network, thereby blocking the penetration of oxygen and water vapor into the silver-containing metal layer. Specifically, after photocuring, the aliphatic urethane-acrylate oligomers in the base resin form a highly cross-linked three-dimensional network structure, significantly reducing the gaps between molecular chains and increasing the length and tortuosity of the penetration paths for gas and water vapor molecules. Adjusting the double bond functionality of the terminal hydroxyl polybutadiene diacrylate and polybutadiene dimethacrylate in the resin allows them to provide more cross-linking nodes during the cross-linking reaction under the action of a photoinitiator, further increasing the cross-linking density and making the network structure more compact. The steric hindrance effect of the benzene ring structure in the aromatic polyurethane acrylate effectively restricts the free movement of molecular chain segments, reducing micropore defects formed by chain segment relaxation during curing, thereby improving the overall density of the protective film. The increased cross-linking density and reduced microporous defects enable the protective film to form a dense physical barrier, effectively blocking the penetration paths of oxygen and water vapor in the external environment, slowing down the oxidation rate of the silver-containing metal layer, and thus extending the service life of low-emissivity (LOW-E) glass. Attached Figure Description

[0018] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on the structures shown in these drawings without creative effort.

[0019] Figure 1 A schematic diagram of a structure of an embodiment of the temperable LOW-E glass provided by the present invention; Explanation of icon numbers: 1. Glass substrate, 2. Functional coating, 21. Dielectric layer, 22. Silver-containing metal layer, 23. Protective layer, 3. Protective film.

[0020] The realization of the objective, functional features and advantages of the present invention will be further explained in conjunction with the embodiments and with reference to the accompanying drawings. Detailed Implementation

[0021] 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 a part of the embodiments of the present invention, and not all of the 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.

[0022] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0023] Furthermore, if the embodiments of this invention involve descriptions such as "first" or "second," these descriptions are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the use of "and / or" or "and / or" throughout the text includes three parallel solutions. For example, "A and / or B" includes solution A, solution B, or a solution where both A and B are satisfied simultaneously. Furthermore, the technical solutions of the various embodiments can be combined with each other, but this must be based on the ability of those skilled in the art to implement them. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0024] Low-E glass is a key material in the field of building energy conservation. It is produced by tempering and then cooling temperable low-E glass. Temperable low-E glass has a silver-containing metal layer, a dielectric layer, and a protective layer deposited on its surface. The silver-containing metal layer effectively reflects infrared radiation, thereby achieving energy conservation.

[0025] However, the hardness of the silver-containing metal layer is only about 5B (pencil hardness test), far lower than the 5-6H of the glass substrate. The hardness of the dielectric and protective layers is also low, resulting in insufficient surface hardness of temperable LOW-E glass. During the pre-tempering processing, temperable LOW-E glass undergoes cutting, edge grinding, cleaning, transfer, and storage. Physical contact during these processes, such as friction from cutting wheels and pressure from brushes, easily causes scratches or even breakage, making it difficult for the dielectric and protective layers to effectively protect the silver-containing metal layer. Simultaneously, the silver-containing metal layer is highly susceptible to oxidation in humid air, and the existing dielectric and protective layers lack sufficient density to effectively prevent oxygen and moisture from penetrating into the silver-containing metal layer, leading to oxidation, deterioration, performance degradation, and reduced storage time.

[0026] In summary, temperable LOW-E glass faces technical challenges due to insufficient hardness and density, and there is an urgent need for a protective film that combines high hardness and high density to provide effective protection for temperable LOW-E glass.

[0027] To address the aforementioned technical problems, this technical solution proposes a protective film, the raw materials for which the protective film is prepared include acrylate resin, acrylate monomer, and photoinitiator; The acrylate resin includes a base resin and a conditioning resin; The base resin includes aliphatic urethane-acrylate oligomers; The conditioning resin includes at least one of hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate.

[0028] In this technical solution, the base resin is an aliphatic urethane-acrylate oligomer. The urethane bonds in its molecular structure endow the protective film with excellent flexibility and elastic recovery. When subjected to external forces such as friction from a cutting wheel or pressure from a brush, it can effectively buffer stress concentration through the elastic deformation of the molecular chain segments, reducing the risk of scratches on the film surface. At the same time, the aliphatic structure on the main chain of this oligomer avoids the rigid brittleness tendency caused by aromatic groups, further enhancing the impact toughness of the protective film. On this basis, adjusting the hydroxyl-terminated polybutadiene diacrylate and polybutadiene dimethacrylate in the resin to contain long-chain polybutadiene soft segments can increase the length of the flexible chain segments in the crosslinking network, giving the protective film higher elongation at break and tear strength, making the protective film less prone to microcracks when subjected to repeated friction. Aromatic polyurethane acrylate, due to its rigid benzene ring structure, forms hard segment microregions in the system, improving the surface hardness and scratch resistance of the protective film through microphase separation structure. The proper combination of soft and hard segments allows the protective film to maintain flexibility while possessing sufficient surface hardness, effectively resisting mechanical damage during the pre-tempering processing stage, thus protecting the silver-containing metal layer.

[0029] Secondly, the aliphatic urethane-acrylate oligomer in the base resin of this technical solution provides a flexible main chain structure, giving the protective film a lower glass transition temperature. This allows the surface molecular segments to migrate after curing, reducing surface viscous resistance. Adjusting the polybutadiene segments in the hydroxyl-terminated polybutadiene diacrylate and polybutadiene dimethacrylate in the resin to have non-polar hydrophobic properties reduces the surface energy of the protective film, weakening the adhesion effect during external force contact. Simultaneously, the long-chain flexible structure forms a micro-smooth layer on the protective film surface, reducing the meshing effect between friction pairs. The aromatic polyurethane acrylate, through the introduction of rigid benzene rings, appropriately adjusts the density of the crosslinking network, preventing excessive crosslinking from causing surface brittleness and increasing the coefficient of friction. Through the rational blending of soft and hard segments and the optimization of crosslinking density, the protective film surface maintains sufficient mechanical strength while having a low coefficient of friction, effectively resisting mechanical damage during the pre-tempering processing stage, thus protecting the silver-containing metal layer.

[0030] Furthermore, this technical solution enhances the density of the protective film through the molecular structure design and cross-linking network construction of the acrylate resin, thereby blocking the penetration of oxygen and water vapor into the silver-containing metal layer. Specifically, after photocuring, the aliphatic urethane-acrylate oligomers in the base resin form a highly cross-linked three-dimensional network structure, significantly reducing the gaps between molecular chains and increasing the penetration path length and tortuosity of gas and water vapor molecules. Adjusting the double bond functionality of the terminal hydroxyl polybutadiene diacrylate and polybutadiene dimethacrylate in the resin allows them to provide more cross-linking nodes during the cross-linking reaction under the action of a photoinitiator, further increasing the cross-linking density and making the network structure more compact. The steric hindrance effect of the benzene ring structure in the aromatic polyurethane acrylate effectively restricts the free movement of molecular chain segments, reducing micropore defects formed by chain segment relaxation during curing, thereby improving the overall density of the protective film. The increased cross-linking density and reduced microporous defects enable the protective film to form a dense physical barrier, effectively blocking the penetration paths of oxygen and water vapor in the external environment, slowing down the oxidation rate of the silver-containing metal layer, and thus extending the service life of low-emissivity (LOW-E) glass.

[0031] Finally, the polar groups (such as ester groups and hydroxyl groups) of the acrylate monomers in the protective film and the polar urethane groups in the aliphatic urethane-acrylate oligomers can form van der Waals forces with the surface of the LOW-E glass substrate, thereby improving the adhesion between the protective film and the LOW-E glass substrate.

[0032] It should be noted that the photoinitiator can be 1173, 907, and TPO, etc., and the specific type is not limited here. The hydroxyl-terminated polybutadiene diacrylate can be a commercially available product, such as NISSO PBTEAI-1000 or TE-2000 manufactured by Nippon Soda Co., Ltd.; the polybutadiene dimethacrylate can be a commercially available product, such as FSP8002 manufactured by Runao Chemical (Guangzhou) Co., Ltd.; the aromatic polyurethane acrylate can be a commercially available product, such as the CN series (e.g., CN104, CN120) manufactured by Sartoma (Guangzhou) Chemical Co., Ltd., or the SM series (e.g., SM6329) manufactured by Multipurpose Chemical (Guangdong) Co., Ltd.

[0033] Preferably, the acrylate monomers include trifunctional acrylate monomers and difunctional acrylate monomers; The mass mixing ratio of the difunctional acrylate monomer and the trifunctional acrylate monomer is (1-2):1.

[0034] Trifunctional acrylate monomers provide sufficient crosslinking nodes to ensure the film's density and hardness, thus blocking water and oxygen penetration and resisting scratches. Difunctional acrylate monomers introduce flexible segments, giving the film toughness and preventing excessive crosslinking from causing brittleness. The mass mixing ratio of difunctional and trifunctional acrylate monomers is limited to (1-2):1. Within this ratio range, they work synergistically to give the protective film both high density and good impact resistance, effectively solving the technical problem of insufficient hardness and density in protective films.

[0035] The difunctional acrylate monomers include at least one of tricyclodecanediethanol diacrylate, dicyclopentadienediethanolpropane and 1,4-cyclohexanediethanol diacrylate. The trifunctional acrylate monomer includes at least one of trimethylolpropane triacrylate, ethoxylated trimethylolpropane triacrylate, and propoxylated trimethylolpropane triacrylate.

[0036] Preferably, the raw materials for preparing the aliphatic urethane-acrylate oligomer include diols, diisocyanates, and monohydroxy acrylates; The molar ratio of the diol, the diisocyanate, and the monohydroxy acrylate is 1:(1.8-2.2):(0.9-1.1).

[0037] In this technical solution, diisocyanate and diol react first to generate prepolymer segments, followed by the addition of monohydroxy acrylate. Since diisocyanate is in a slight excess relative to diol, this ensures that the hydroxyl groups at both ends of the diol are fully reacted to form prepolymer segments, and that a suitable amount of free -NCO is retained at the ends of the prepolymer. Furthermore, the monohydroxy acrylate (molar ratio 0.9-1.1) is added later; the -OH groups in the hydroxy acrylate can react with the -NCO at the ends of the prepolymer to achieve end-capping. The monohydroxy acrylate can be added in an equivalence or slight excess, ensuring that the free -NCO in the system is fully consumed, avoiding excessive residue that could lead to gelation in subsequent formulations or an excessively narrow operating window. Simultaneously, the small amount of residual -NCO left by the slight excess diisocyanate can also undergo chain extension / crosslinking reactions with the terminal hydroxyl groups of the terminal hydroxyl polybutadiene diacrylate in the adjusting resin during subsequent protective film formulations, enhancing the interfacial compatibility between the base resin and the adjusting resin.

[0038] Preferably, the diol includes at least one of polycaprolactone diol, polycarbonate diol, and polybutanediol; The diisocyanate includes at least one of phorone diisocyanate, dicyclohexylmethane diisocyanate and hexamethylene diisocyanate; The monohydroxy acrylate includes at least one of hydroxyethyl acrylate, hydroxyethyl methacrylate, and hydroxypropyl acrylate.

[0039] Preferably, the thickness of the protective film is 1-100 μm.

[0040] If the protective film is too thin, it will not provide sufficient physical isolation and anti-oxidation protection for the Low-E coating, and the silver layer will be easily scratched or oxidized and fail during storage and transportation. If the protective film is too thick, it will not only increase the coating cost and curing energy consumption, but may also cause excessive gas and residues to be generated due to the decomposition of organic components during high-temperature tempering, resulting in increased carbon residue or film cracking. In addition, excessive thickness deviation will affect the uniformity of tempering cooling, ultimately reducing the strength and optical performance of Low-E glass.

[0041] In embodiments of the present invention, the properties of the aliphatic urethane-acrylate oligomer satisfy at least one of the following conditions: (1) Viscosity is 1000-3000 mPa·s; (2) Solid content ≥ 99 wt%; (3) The initial decomposition temperature is 280-500℃; (4) The rate of change of viscosity within 72 hours is ≤ ±5%; (5) Glass transition temperature Tg < 80℃.

[0042] The viscosity of the aliphatic urethane-acrylate oligomer, ranging from 1000 to 3000 mPa·s, and its solid content, ≥99wt%, ensures easy coating operation and solvent-free environmental friendliness. The initial decomposition temperature of 280-500℃ ensures the protective film is essentially decomposed during the high-temperature tempering process of temperable LOW-E glass, preventing carbon residue from clogging the pores of the LOW-E glass and ensuring its purity. A viscosity change rate of ≤±5% within 72 hours ensures storage stability and prevents coating quality instability due to viscosity fluctuations during storage. A glass transition temperature (Tg) <80℃ keeps the film in a highly elastic state at room temperature, with sufficient molecular chain mobility, giving the protective film good flexibility and impact resistance, effectively buffering external forces.

[0043] In an embodiment of the present invention, the glass transition temperature Tg of the hydroxyl-terminated polybutadiene diacrylate is < 80°C. And / or, the glass transition temperature Tg of the polybutadiene dimethacrylate is < 80°C; And / or, the glass transition temperature Tg of the aromatic polyurethane acrylate is < 80°C.

[0044] By limiting the glass transition temperatures of hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate, the conditioning resin is kept in a highly elastic state at room temperature, with sufficient molecular chain mobility to effectively absorb and disperse external impacts, preventing the protective film from becoming brittle due to excessive rigidity. Simultaneously, a lower Tg helps reduce the viscous resistance of the film, giving it good flexibility and impact resistance. During the processing stage before high-temperature tempering of temperable LOW-E glass, it is less prone to cracking or peeling when subjected to physical contact such as blade friction and brush pressure. Furthermore, the conditioning resin with Tg < 80℃ has a similar glass transition temperature range to the base resin (aliphatic urethane-acrylate oligomer, Tg < 80℃), which helps improve the compatibility between the base and conditioning resins, preventing microphase separation due to excessive Tg differences, thus ensuring the uniformity and stability of the cured protective film.

[0045] In an embodiment of the present invention, the mass ratio of the base resin to the conditioning resin is (9-10):1; And / or, the conditioning resin includes hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate; The mass mixing ratio of the hydroxyl-terminated polybutadiene diacrylate, the polybutadiene dimethacrylate, and the aromatic polyurethane acrylate is (0.5-1):(0.5-1):1.

[0046] In this scheme, the mass ratio of base resin to modifier resin is (9-10):1. The base resin is the main component to ensure the basic mechanical properties and crosslinking framework of the film. The introduction of a small amount of modifier resin plays a key modifying role, avoiding excessive modifier resin which would lead to excessive viscosity or deterioration of mechanical properties. The modifier resin is compounded with hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate in a ratio of (0.5-1):(0.5-1):1. The polybutadiene segments contained in the hydroxyl-terminated polybutadiene diacrylate and polybutadiene dimethacrylate provide non-polar hydrophobic properties, reducing the surface energy of the film and imparting flexibility; the rigid benzene ring structure of the aromatic polyurethane acrylate increases the hardness and crosslinking density of the film. By limiting the above ratio range, a balance is achieved between flexibility, surface hardness, and density in the protective film.

[0047] In an embodiment of the present invention, the content of the acrylate resin in the raw materials for preparing the protective film is 50-70 wt%. And / or, the acrylate monomer is present in the raw materials for preparing the protective film at a content of 25-49 wt%; And / or, the photoinitiator is present in the raw materials for preparing the protective film at a content of 1-5 wt%.

[0048] Acrylic resin serves as the main film-forming agent, with an addition of 50-70 wt% to establish the basic mechanical framework and crosslinking density of the film. Acrylic monomer, acting as an active diluent and crosslinking agent, has an addition of 28-49 wt% to adjust the system viscosity to a suitable coating process window, while providing sufficient polymerizable functional groups to participate in curing and crosslinking. The addition of photoinitiator, at 1-5 wt%, must be controlled within the minimum effective range to ensure initiation efficiency and avoid residual initiator affecting the optical properties or weather resistance of the film. The limited addition of these three agents achieves a balance between curing speed, crosslinking density, and film performance, ensuring coating uniformity and high hardness and density of the cured film.

[0049] The present invention also proposes a temperable LOW-E glass, wherein the temperable LOW-E glass comprises a LOW-E glass sheet and a protective film 3 as described above located on the surface of the LOW-E glass sheet; The LOW-E glass substrate includes a glass substrate 1 and a functional coating 2 disposed on the surface of the glass substrate; The functional coating comprises, from the inside out, a functional layer and a protective layer 23; The functional layer includes n+1 dielectric layers 21 and n silver-containing metal layers 22. The dielectric layers 21 and the silver-containing metal layers 22 are stacked alternately from the inside to the outside, and the silver-containing metal layers 22 are located between two adjacent dielectric layers 21, where n≥1. The protective layer 23 is located on the outermost side of the functional coating 2.

[0050] This technical solution involves applying a protective film to the surface of the LOW-E glass substrate. Utilizing the high hardness and density of this protective film, the temperable LOW-E glass not only resists mechanical damage during cutting, edge grinding, cleaning, and transportation, but also prevents oxygen and moisture from penetrating into the silver-containing metal layer 22 within the temperable LOW-E glass, thus preventing oxidation and failure of the silver-containing metal layer 22, thereby extending its storage time under natural conditions. It should be noted that the functional coating 2 is prepared using conventional methods in existing technologies, the details of which will not be elaborated here.

[0051] Preferably, the dielectric layer 21 is made of at least one of silicon nitride, aluminum oxide, and tin oxide; And / or, the material of the protective layer 23 includes at least one of titanium nitride, zirconium oxide and hafnium oxide.

[0052] Preferably, 1 ≤ n ≤ 4; And / or, the thickness of the functional coating 2 is 100-300 nm; And / or, the silver content in the silver-containing metal layer 22 is >50wt%.

[0053] With 1≤n≤4, while ensuring heat insulation and reflection, the total thickness and stress are controlled to avoid excessive layers that would reduce adhesion and light transmittance.

[0054] If the thickness of functional coating 2 is too thin (<100nm), its function may be insufficient (such as the heat insulation effect is not up to standard); if the thickness of functional coating is too thick (>300nm), it is easy to generate internal stress, film cracking, and increase cost.

[0055] The silver content in the silver-containing metal layer 22 is >50wt%, ensuring that the silver-containing metal layer 22 serves as the main functional element of the infrared reflective layer, guaranteeing low-emissivity (Low-E) and thermal insulation performance.

[0056] In an embodiment of the present invention, the hardness of the temperable LOW-E glass is ≥6H; And / or, the surface friction coefficient of the temperable LOW-E glass is <0.3; And / or, the surface porosity of the temperable LOW-E glass is ≤0.2%; And / or, the oxygen transmittance of the temperable LOW-E glass is <0.1 cm. 3 ·μm / (m 2 (day MPa); And / or, the water vapor transmission rate of the temperable LOW-E glass is <0.5 g / (m²). 2 ·day); And / or, the adhesion between the protective film and the original LOW-E glass in the temperable LOW-E glass is ≥90%; And / or, the residual carbon content of the protective film in the temperable LOW-E glass is <0.1wt% at a tempering temperature of 550-720°C.

[0057] A hardness ≥6H ensures that the surface hardness of temperable LOW-E glass is higher than that of the glass substrate (5-6H) and the silver-containing metal layer (5B), effectively resisting blade friction and brush pressure during cutting, edge grinding, and other processes, thus preventing scratches on the film surface; a surface friction coefficient <0.3 reduces the friction between the contact tools and the film surface during processing, minimizing scratches; porosity ≤0.2%, oxygen permeability <0.1 cm⁻². 3 ·μm / (m 2 (day·MPa) and water vapor transmission rate <0.5 g / (m 2 • day) Collaborative construction of a highly dense barrier layer effectively blocks oxygen and moisture from penetrating into the silver-containing metal layer, delaying the oxidation of the silver-containing metal layer; adhesion ≥90% ensures that the protective film does not peel or flake during processing and use, maintaining a long-term effective protective effect; residual carbon rate <0.1wt% ensures that the protective film is almost completely decomposed and volatilized at high temperatures (550-720℃) during the tempering process, leaving no residue to contaminate the glass surface and not affecting the optical performance and appearance quality of the final LOW-E glass.

[0058] This invention also proposes a method for preparing temperable LOW-E glass, comprising the following steps: A. Weigh the protective film raw materials according to the above composition and mix them to obtain the protective film coating; B. Apply the protective coating to the surface of the LOW-E glass substrate, and after UV curing, form a protective film to obtain the temperable LOW-E glass as described above.

[0059] By coating the surface of the LOW-E glass sheet with a protective film that can be burned off during tempering, the technical problems of easy mechanical damage and limited storage time of the LOW-E glass sheet during cutting, edge grinding, cleaning and transportation are solved.

[0060] Preferably, in step B, the UV curing irradiation intensity is 200-500 mJ / cm². 2 The time is 0.1-1 min.

[0061] By limiting the irradiation intensity and time of UV curing, the protective film coating is ensured to achieve complete cross-linking and curing in a short time, forming a dense and uniform protective film. This not only ensures that the film layer fully covers and protects the underlying LOW-E glass substrate, but also avoids thermal damage or oxidation to sensitive materials such as silver-containing metal layers caused by excessively long-term or high-energy irradiation.

[0062] The preparation method of the aliphatic urethane-acrylate oligomer is as follows: under an inert atmosphere, diol and diisocyanate are added to a reaction vessel and reacted at a constant temperature of 80-85°C until the content of isocyanate groups is ≤0.5wt%; then monohydroxy acrylate and antioxidant are added, and the reaction continues until the content of free isocyanate groups in the system is <0.1%; after the reaction is completed, degassing is performed under reduced pressure to obtain the urethane-acrylate oligomer.

[0063] In an embodiment of the present invention, step B further includes cutting, edge grinding and cleaning the temperable LOW-E glass, wherein the size after cleaning deviates from the finished size of the LOW-E glass by ≤ ±0.5mm.

[0064] Edge grinding eliminates micro-cracks caused by cutting, preventing glass breakage due to stress concentration during tempering. Thorough cleaning removes surface oil and dust, preventing surface defects after high-temperature tempering and thus improving tempering yield. Furthermore, controlling dimensional deviations after cutting, edge grinding, and cleaning to within ±0.5mm ensures precise glass dimensions during subsequent tempering, lamination, or installation, meeting assembly tolerance requirements and providing excellent interchangeability.

[0065] The present invention also proposes a LOW-E glass, which is prepared by tempering and cooling the above-mentioned temperable LOW-E glass.

[0066] This invention utilizes temperable LOW-E glass at 550-720℃. At this temperature, not only can the performance of LOW-E glass be improved, but it is also beneficial to almost completely decompose and remove the protective film in the temperable LOW-E glass, avoiding carbon residue from clogging the coating pores, and obtaining pure LOW-E glass.

[0067] The technical solution of the present invention will be further described in detail below with reference to specific embodiments. It should be understood that the following specific embodiments are only used to explain the present invention and are not intended to limit the present invention.

[0068] The preparation methods of the aliphatic urethane-acrylate oligomers in the embodiments and comparative examples of this invention are as follows: Under an inert atmosphere and under nitrogen protection, 100g of polycaprolactone diol and 44.4g of isophorone diisocyanate are added to a four-necked flask equipped with a mechanical stirrer, thermometer, and condenser. The temperature is raised from room temperature to 80°C at a rate of 5°C / min and held at the temperature until the content of isocyanate groups is ≤0.5wt%. Subsequently, 23.2g of hydroxyethyl acrylate and 0.05g of antioxidant 2,6-di-tert-butyl-p-cresol are added, and the reaction continues until the content of free isocyanate groups in the system drops to <0.1%. After the reaction is completed, the pressure is reduced and degassed to obtain a light yellow, transparent, viscous liquid urethane-acrylate oligomer. The viscosity of the urethane-acrylate oligomer is 1000 mPa·s, the solid content is 99wt%, the initial decomposition temperature is 300°C, the viscosity change rate within 72h is ≤±5%, and the glass transition temperature Tg is 75°C.

[0069] Examples 1-5 and Comparative Examples 1-2 The preparation method of temperable LOW-E glass is as follows: A. Weigh the raw materials for the protective film according to the composition of the protective film in Table 1 and mix them to obtain the protective film coating. B. Apply the protective coating to the surface of the LOW-E glass substrate, and after UV curing, form a protective film with a thickness of 5μm to obtain temperable LOW-E glass; LOW-E glass substrate includes a glass substrate and a functional coating disposed on the surface of the glass substrate; The functional coating consists of, from the inside out, a dielectric layer (50 nm thick, made of silicon nitride), a silver-containing metal layer (10 nm thick, with 60 wt% silver and 40 wt% niobium), a dielectric layer (50 nm thick, made of silicon nitride), and a protective layer (30 nm thick, made of zirconium oxide).

[0070] Table 1. Raw materials (wt%) for the preparation of protective films in the examples and comparative examples.

[0071] The temperable LOW-E glass prepared in the examples and comparative examples was subjected to performance tests according to the following methods: Hardness: Referring to GB / T 6739-2022 "Determination of Hardness of Paints and Varnishes by Pencil Method", a set of Zhonghua brand high-grade drawing pencils (9H to 6B) with different hardness grades were used. The wood part of the pencil was shaved off to expose a lead of about 5-6 mm. The lead was placed vertically on sandpaper and the end face of the lead was ground flat to a circular cross-section with a diameter of 0.5 mm and no debris at the edge. The prepared temperable Low-E glass sample was fixed horizontally on a stable table. The pencil was fixed at a 45° angle to the sample surface using a pencil hardness tester or manually. A load of 500g or 750g was applied and the pencil was pushed forward about 6-7 mm at a speed of about 1 mm / s. Five scratches were made at different positions on the sample surface with each pencil. After each scratch, the surface was gently wiped with an eraser or a soft cloth. The sample surface was observed with the naked eye under diffused light to see if there were any scratches or traces of coating penetration. The highest pencil hardness grade that did not show scratches was taken as the pencil hardness value of the sample. Each sample was tested at least 3 times to obtain consistent results.

[0072] Surface friction coefficient: The friction coefficient tester is used. The temperable LOW-E glass sample is fixed horizontally on the test platform. A slider of specified material and size (such as stainless steel or rubber slider) is placed on the sample surface. A certain normal load (such as 5N) is applied. The slider is pulled horizontally at a constant speed (such as 100mm / min). The friction force during the sliding process is recorded by the force sensor. The friction coefficient is obtained by calculating the ratio of friction force to normal load. The average value of three tests is taken.

[0073] Surface porosity: The mercury intrusion porosimetry method was used for testing. The temperable LOW-E glass sample was cut into a suitable size and placed in the dilatometer of the mercury intrusion porosimetry instrument. After sealing, a vacuum was drawn, and mercury was forced into the pores on the surface of the protective film under gradually increasing pressure. Based on the relationship between the mercury intrusion pressure and the mercury intrusion volume, the pore volume and porosity (%) were calculated according to the Washburn equation. Before the test, the sample needs to be dried to constant weight at 105℃.

[0074] Oxygen permeability: The gas permeation test was conducted using a differential pressure method. A temperable LOW-E glass sample was sealed in the permeation chamber as a partition. After evacuating both sides of the sample, high-purity oxygen (pressure 0.1 MPa) was introduced into one side, while the other side was kept under vacuum. The rate of change of oxygen pressure on the low-pressure side over time was monitored by a sensor, and the oxygen permeability was calculated according to the corresponding formula. The test conditions were a temperature of 23±2℃ and a relative humidity of 50±5%RH.

[0075] Water vapor transmission rate: The test was conducted using a cup weighing method. The temperable LOW-E glass sample was cut into a circle and sealed in the mouth of a permeation cup containing a desiccant (anhydrous calcium chloride). The permeation cup was placed in a constant temperature and humidity chamber (temperature 38±2℃, relative humidity 90±2%RH). The sample was weighed every 24 hours for a total of 7 times. The water vapor transmission rate was calculated by dividing the increase in weight of the permeation cup per unit time by the sample area.

[0076] The adhesion between the protective film and the Low-E glass substrate was tested using the cross-cut test. A 10×10 grid (100 grids in total) with a spacing of 1mm was made on the surface of the protective film using a cross-cutting tool. The scratches had to penetrate the protective film to the Low-E glass substrate. After removing the scratch debris with a soft brush, 3M 600 tape was applied to the grid area and pressed firmly. The tape was then quickly and vertically peeled off. The number of grids in the protective film that had come off was counted under a magnifying glass. The adhesion percentage was calculated using the formula (Adhesion rate = 100% - Number of grids that came off / 100×100%). The average value was taken from at least 3 different locations.

[0077] Carbon residue rate: Thermogravimetric analysis (TGA) was used for testing. Approximately 5-10 mg of protective film sample was weighed and placed in a platinum crucible of the thermogravimetric analyzer. The temperature was increased from room temperature to 700℃ at a rate of 10℃ / min under air atmosphere. The change curve of sample mass with temperature was recorded. Carbon residue rate was calculated according to the formula (carbon residue rate = residual mass at 700℃ / initial mass × 100%) to evaluate the degree of complete decomposition of the protective film during high-temperature sintering.

[0078] Storage period: Temperable Low-E glass sheets from the same batch were cut to the same size (e.g., 100mm × 100mm), and a total of 6 groups of samples were selected. Five groups were samples with a protective film coating, and one group was a blank control group without a protective film coating. Before testing, the initial visible light transmittance of each group of samples was measured using a UV-Vis spectrophotometer (wavelength 380-780nm), the sheet resistance of the film was measured using a four-probe tester, and the film surface was visually inspected under strong light and photographed for record-keeping. The 6 groups of samples were placed under natural conditions, and samples were taken out every 24 hours for periodic inspection. The inspection included: observing the film surface with the naked eye or a magnifying glass under strong light for oxidation points, discoloration spots, or corrosion areas, and re-measuring transmittance and sheet resistance. A sample was considered to have failed due to oxidation when any of the following phenomena were observed: visible oxidation points or discoloration spots on the film surface, a decrease in transmittance exceeding 0.5% from the initial value, or a change in sheet resistance exceeding 5%. Record the time from the start of the test to the appearance of oxidation failure for each group of samples. The earliest time of oxidation among the five groups of samples coated with protective film is used as the basis for determining the storage period of this batch of products.

[0079] Table 2 Performance of temperable LOW-E glass in the Examples and Comparative Examples

[0080] As shown in Table 2, the performance test results of the temperable LOW-E glass in each embodiment demonstrate that the temperable LOW-E glass of this technical solution has a hardness ≥6H, a surface friction coefficient <0.3, a porosity ≤0.2%, and an oxygen permeability <0.1 cm⁻¹. 3 ·μm / (m 2 • day • MPa), water vapor transmission rate < 0.5 g / (m 2 The adhesion between the protective film and the original LOW-E glass is ≥90% and the residual carbon content is <0.1wt%. It has both high hardness and density, which improves the hardness, resistance to mechanical damage and storage time of temperable LOW-E glass, effectively solving the technical problems of mechanical damage resistance and short storage time of temperable LOW-E glass.

[0081] In Comparative Example 1, the absence of conditioning resin and in Comparative Example 2, the absence of base resin, resulted in a decrease in properties such as hardness and density, which failed to meet the usage requirements.

[0082] The above description is merely an exemplary embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural transformations made using the contents of the present invention specification and drawings under the technical concept of the present invention, or direct / indirect applications in other related technical fields, are included within the patent protection scope of the present invention.

Claims

1. A protective film, characterized in that, The raw materials for preparing the protective film include acrylate resin, acrylate monomer and photoinitiator; The acrylate resin includes a base resin and a conditioning resin; The base resin includes aliphatic urethane-acrylate oligomers; The conditioning resin includes at least one of hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate.

2. The protective film as described in claim 1, characterized in that, The properties of the aliphatic urethane-acrylate oligomers satisfy at least one of the following conditions: (1) Viscosity is 1000-3000 mPa·s; (2) Solid content ≥ 99 wt%; (3) The initial decomposition temperature is 280-500℃; (4) The rate of change of viscosity within 72 hours is ≤ ±5%; (5) Glass transition temperature Tg < 80℃.

3. The protective film as described in claim 1, characterized in that, The glass transition temperature Tg of the hydroxyl-terminated polybutadiene diacrylate is < 80℃. And / or, the glass transition temperature Tg of the polybutadiene dimethacrylate is < 80°C; And / or, the glass transition temperature Tg of the aromatic polyurethane acrylate is < 80°C.

4. The protective film as described in claim 1, characterized in that, The mass ratio of the base resin to the conditioning resin is (9-10):1; And / or, the conditioning resin includes hydroxyl-terminated polybutadiene diacrylate, polybutadiene dimethacrylate, and aromatic polyurethane acrylate; The mass mixing ratio of the hydroxyl-terminated polybutadiene diacrylate, the polybutadiene dimethacrylate, and the aromatic polyurethane acrylate is (0.5-1):(0.5-1):

1.

5. The protective film as described in claim 1, characterized in that, The acrylate resin content in the raw materials for preparing the protective film is 50-70 wt%. And / or, the acrylate monomer is present in the raw materials for preparing the protective film at a content of 25-49 wt%; And / or, the photoinitiator is present in the raw materials for preparing the protective film at a content of 1-5 wt%.

6. A temperable LOW-E glass, characterized in that, The temperable LOW-E glass includes a LOW-E glass sheet and a protective film as described in any one of claims 1 to 5 located on the surface of the LOW-E glass sheet; The LOW-E glass substrate includes a glass substrate and a functional coating disposed on the surface of the glass substrate; The functional coating comprises, from the inside out, a functional layer and a protective layer; The functional layer includes n+1 dielectric layers and n silver-containing metal layers, wherein the dielectric layers and the silver-containing metal layers are alternately stacked from the inside to the outside, and the silver-containing metal layers are located between two adjacent dielectric layers, and n≥1; The protective layer is located on the outermost side of the functional coating.

7. The temperable LOW-E glass as described in claim 6, characterized in that, The hardness of the temperable LOW-E glass is ≥6H; And / or, the surface friction coefficient of the temperable LOW-E glass is <0.3; And / or, the surface porosity of the temperable LOW-E glass is ≤0.2%; And / or, the oxygen permeability of the temperable LOW-E glass is <0.1 cm. 3 ·μm / (m 2 (day MPa); And / or, the water vapor transmission rate of the temperable LOW-E glass is <0.5 g / (m²). 2 ·day); And / or, the adhesion between the protective film and the original LOW-E glass in the temperable LOW-E glass is ≥90%; And / or, the residual carbon content of the protective film in the temperable LOW-E glass is <0.1wt% at a tempering temperature of 550-720°C.

8. A method for preparing temperable LOW-E glass, characterized in that, Includes the following steps: A. Weigh and mix the protective film raw materials according to the composition of the protective film according to any one of claims 1-5 to obtain the protective film coating. B. Apply a protective coating to the surface of the original LOW-E glass sheet, and after UV curing, form a protective film to obtain the temperable LOW-E glass as described in any one of claims 6-7.

9. The method for preparing temperable LOW-E glass as described in claim 8, characterized in that, Step B also includes cutting, edge grinding, and cleaning the temperable LOW-E glass, with the dimensions after cleaning deviating from the finished LOW-E glass dimensions by ≤±0.5mm.

10. A LOW-E glass, characterized in that, The LOW-E glass is prepared by tempering and cooling the temperable LOW-E glass as described in any one of claims 6 to 7.

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