PVB (polyvinyl butyral) composite glass laminated body with independent conductive structure and preparation method of PVB composite glass laminated body

Abstract

The invention relates to the technical field of automobile glass manufacturing, in particular to a PVB (polyvinyl butyral) composite glass laminated body with an independent conductive structure and a preparation method of the PVB composite glass laminated body. The PVB composite glass laminated body with the independent conductive structure comprises a first glass plate, a PVB-based middle layer and a second glass plate which are sequentially laminated, and an independent conductive preformed part is arranged in the PVB-based middle layer. By adopting the innovative design that the PVB-based middle layer is provided with the independent conductive preformed part, the advantages of high adhesiveness, high light transmission and the like of the PVB middle layer are reserved, and meanwhile a series of problems that in the prior art, a conductive structure and the PVB layer are poor in adaptability, low in long-term reliability, complex in process, high in cost and the like are systematically solved.

Description

Technical Field

[0001] This invention relates to the field of automotive glass manufacturing technology, and in particular to a PVB composite glass laminate with an independent conductive structure and its preparation method. Background Technology

[0002] In the automotive glass manufacturing industry, to achieve the conductive functions of glass laminates (such as heating and antenna signal transmission), a common approach is to use polyvinyl acetal (PVB) as an intermediate layer and integrate conductive structures. Currently, the common methods fall into two main categories: one is to directly fabricate or place the conductive structure on the PVB film or glass surface, for example, by forming conductive patterns through etching or printing; the other is to achieve functional integration through multi-layer PVB composite structures, such as using a combination of PVB layers with different plasticizer contents or adding functional materials to the PVB matrix.

[0003] However, the aforementioned existing technologies still face a series of interconnected challenges in practical applications. The conductive structure, being in direct contact with PVB or glass, is prone to detachment or breakage under the high temperature and pressure of the lamination process. Furthermore, the flexibility of PVB is difficult to match with the rigidity of the conductive structure, leading to unstable conductivity after long-term use. To improve the interfacial bonding and performance compatibility between the conductive structure and the PVB layer, existing technologies often employ multi-layer PVB composites, balancing adhesion and functional requirements by adjusting the plasticizer content in different PVB layers. However, this design can cause plasticizer migration between layers, accelerating PVB aging and reducing interlayer adhesion strength, further increasing the risk of delamination in high-temperature and high-humidity environments. In addition, integrating more functions through PVB matrix blending modification often requires stacking multiple layers, resulting in excessively thick intermediate layers, making it difficult to meet the lightweight and thin design requirements of automotive glass. These factors collectively lead to complex manufacturing processes, high requirements for materials and processing precision in existing solutions, and because the conductive structure is bonded to the PVB layer, local defects can easily lead to overall scrap, resulting in high material waste and low production efficiency.

[0004] Therefore, how to achieve stable integration of conductive structures without affecting the adhesion and optical properties of the PVB interlayer, and how to systematically solve the aforementioned shortcomings in process and reliability, has become an urgent problem to be solved in this field. Summary of the Invention

[0005] The purpose of this invention is to address the problems existing in the prior art by providing a PVB composite glass laminate with an independent conductive structure and its preparation method. By adopting an innovative design of "setting an independent conductive preform in the PVB-based intermediate layer", the invention systematically solves a series of problems in the prior art, such as poor compatibility between the conductive structure and the PVB layer, low long-term reliability, complex process, and high cost, while retaining the advantages of the PVB intermediate layer, such as high adhesion and high light transmittance.

[0006] To achieve the above objectives, the specific technical approach adopted in this invention is as follows: Micron-sized metal wires (such as copper, silver, or silver-plated copper) are selected as the conductive core and prefabricated into independent strip or mesh structures (i.e., conductive cores). By precisely controlling their wire diameter and spatial distribution, they are arranged discretely and discontinuously within the PVB matrix. Visible light primarily passes through the large transparent PVB regions between the metal wires, thus ensuring high light transmittance and low haze of the laminate as a whole while achieving conductivity. Furthermore, compared to nano-conductive materials (such as silver nanowires), this invention uses micron-sized metal wires. This is based on the stringent requirements of automotive glass for long-term conductivity stability, high current carrying capacity, and compatibility with mature processes under extreme environments, thereby systematically guaranteeing the product's service life and functional reliability.

[0007] Specifically, the present invention provides a PVB composite glass laminate with an independent conductive structure, comprising a first glass plate, a PVB base intermediate layer and a second glass plate stacked sequentially; an independent conductive preform is disposed in the PVB base intermediate layer.

[0008] Preferably, the conductive preform includes a conductive core and a PVB layer covering the outer surface of the conductive core.

[0009] Preferably, the conductive core is made of metal and has an equivalent diameter of 0.05-20 μm; the PVB layer has a thickness of 2-4 μm.

[0010] Preferably, the PVB layer contains a silane coupling agent; the content of the silane coupling agent in the PVB layer is 0.2-0.4 wt%.

[0011] Preferably, the PVB-based intermediate layer includes a buffer adapter layer and a main adhesive PVB layer, wherein the buffer adapter layer is located between the first glass plate and the conductive preform, and the main adhesive PVB layer is located between the conductive preform and the second glass plate.

[0012] Preferably, the buffer adapter layer is a modified PVB layer containing nano-calcium carbonate; the content of nano-calcium carbonate in the buffer adapter layer is 0.3-0.8 wt%.

[0013] Preferably, the plasticizer content in the main adhesive PVB layer is 18-25 wt%.

[0014] Preferably, the PVB-based intermediate layer further includes a functionally enhanced PVB layer, which is located between the main adhesive PVB layer and the second glass plate.

[0015] The present invention also provides a method for preparing the PVB composite glass laminate with independent conductive structure, comprising the following steps: S1. The conductive preform is fixed in the PVB base intermediate layer by electrostatic adsorption; the first glass plate, the PVB base intermediate layer, and the second glass plate are stacked in the order of forming a pre-assembled body. S2. The pre-assembled body is subjected to vacuum pre-compression and hot-press curing treatment in sequence to obtain a PVB composite glass laminate with an independent conductive structure.

[0016] Preferably, in S2, the vacuum pre-compression process conditions are: vacuum degree 20-60 mbar, temperature 90-110℃, time 12-18 min; the hot-press curing process conditions are: temperature 120-140℃, pressure 10-14 bar, time 90-120 min.

[0017] The beneficial effects of this invention are as follows: (1) This invention provides a PVB composite glass laminate with an independent conductive structure, comprising a first glass plate, a PVB-based intermediate layer, and a second glass plate stacked sequentially; an independent conductive preform is disposed in the PVB-based intermediate layer. By adopting the innovative design of "an independent conductive preform is disposed in the PVB-based intermediate layer", this invention systematically solves a series of problems in the prior art, such as poor compatibility between the conductive structure and the PVB layer, low long-term reliability, complex process, and high cost, while retaining the advantages of high adhesion and high light transmittance of the PVB intermediate layer.

[0018] (2) The independent conductive preform adopts a double-layer composite structure of “conductive core-PVB layer”. The outer PVB layer and the buffer adapter layer have excellent interfacial bonding force, which effectively avoids problems such as peeling and breakage of the conductive structure during lamination and use, and ensures the long-term stability of the conductive path.

[0019] (3) The main adhesive PVB layer of the present invention uses a single and moderate plasticizer content (18-25wt%), which avoids the risk of PVB aging, interlayer adhesion strength reduction and delamination under high temperature and high humidity caused by plasticizer migration, and extends the service life of the product.

[0020] (4) By co-extruding the optional functional enhancement PVB layer with the main adhesive PVB layer, a modular integration of multiple functions can be achieved without significantly increasing the total thickness of the intermediate layer. This is particularly suitable for scenarios such as car windshields, side windows, and sunroofs that require weight, optical performance, and functional integration.

[0021] (5) Conductive preforms can be prefabricated in batches and precisely positioned and fixed by electrostatic adsorption, eliminating the need to directly process conductive structures on the PVB film. This process route reduces the number of steps and improves production efficiency; at the same time, because the conductive structure is separated from the PVB film, local errors only require replacement of the preform, reducing material loss rate.

[0022] (6) The resulting composite glass laminate not only has excellent initial bonding strength and high light transmittance, but also maintains high bonding strength and low conductivity decay rate after harsh environmental tests (such as boiling water, high and low temperature cycling, high temperature and high humidity), fully meeting the strict requirements of automotive glass for long-term structural safety, functional stability and weather resistance.

[0023] (7) All the processes involved in this invention can be realized on existing mature automotive glass production equipment without the need for additional special equipment. The technology transfer threshold is low and it is easy to achieve large-scale and stable production.

[0024] (8) This invention prefabricates opaque micron-sized metal wires into independent strip or mesh structures, cleverly separating the "conductive channel" and the "transparent channel" at the physical level, thereby achieving the integration of highly reliable conductive functions without sacrificing the light transmittance and optical quality of the glass. This design fundamentally avoids the durability, cost, or process stability problems commonly encountered when using transparent conductive oxide (ITO) or nanomaterials. Detailed Implementation

[0025] The present invention provides a PVB composite glass laminate with an independent conductive structure, comprising a first glass plate, a PVB base intermediate layer and a second glass plate stacked sequentially; an independent conductive preform is disposed in the PVB base intermediate layer.

[0026] In this invention, the conductive preform includes a conductive core and a PVB layer covering the outer surface of the conductive core.

[0027] As independent conductive units, the key characteristic of conductive preforms lies in their discrete structure. They can be processed into specific design forms, such as woven into a mesh structure with aperture sizes much larger than the wire diameter (0.1-0.4 mm), or cut into sparsely distributed strip structures (0.05-0.15 mm wide). This design allows light to pass through the transparent areas between the metal structures, achieving high visual transmittance of the laminate on a macroscopic scale, thus resolving the inherent contradiction between integrating opaque conductive materials into glass and maintaining light transmittance.

[0028] In this invention, the conductive core is made of metal, and the equivalent diameter of the conductive core is 0.05-20μm, preferably 3-15μm; the thickness of the PVB layer is 2-4μm.

[0029] In this invention, the size range of the conductive core is an optimal result after comprehensively balancing light transmittance, conductivity, long-term reliability, and process feasibility. On the one hand, this size is sufficient to ensure extremely low volume resistivity and excellent mechanical strength, meeting the requirements of automotive glass for high current carrying capacity and long-term physical stability in functions such as heating and antennas; on the other hand, this size is far smaller than the resolution limit of the human eye, and will not cause significant visual interference.

[0030] In this invention, depending on the application scenario, the conductive core can theoretically also be made of nanoscale materials (such as metal nanowires or carbon nanotubes with an equivalent diameter of 50-500 nm), but this invention explicitly prefers the aforementioned micron-scale solution. The main reason is that nanomaterials have a large specific surface area, and under the long-term humid, hot, ultraviolet, and electric field environments faced by automotive glass, there are high risks of oxidation, electrochemical migration, and performance degradation. Furthermore, the maturity of their processes and cost control are not conducive to the large-scale stable production of automotive-grade products.

[0031] In this invention, the metallic material is selected from at least one of copper and silver.

[0032] In this invention, the PVB layer contains a silane coupling agent; the silane coupling agent is selected from KH560; the content of the silane coupling agent in the PVB layer is 0.2-0.4 wt%.

[0033] In this invention, the method for preparing the conductive preform includes the following steps: (1) Conductive core is prepared by melt spinning: Metal materials are smelted in an inert atmosphere to obtain a melt; the melt is placed in a holding furnace and left to stand; after standing, it is extruded through a spinneret and cooled and solidified in a cooling medium, and then stretched and refined by traction rollers to obtain a conductive core.

[0034] (2) Preparation of PVB coating solution: The specific composition of the PVB coating solution (by mass percentage) is as follows: PVB 18-22%, silane coupling agent 0.2-0.4%, plasticizer 2-4%, leveling agent 0.05-0.15%, and solvent balance.

[0035] The preparation method includes the following steps: mixing the above components, stirring at 40-50℃ for 2-3 hours, filtering and degassing to obtain a PVB coating solution; the viscosity of the obtained PVB coating solution at 25℃ is 40-50 mPa·s.

[0036] (3) Using a precision dip coating method, the conductive core is passed through the PVB coating liquid tank at a speed of 5-10 m / min, and then enters a three-stage drying channel: first, it is pre-dried at 75-85℃ for 1-3 min (to remove most of the solvent), then cured at 115-125℃ for 4-6 min (to form a dense coating layer), and finally cooled at room temperature, thereby forming a PVB layer with uniform thickness and excellent adhesion on the surface of the conductive core; according to the functional requirements of the final product, it can be further processed into a specific design shape, such as weaving it into a mesh structure with a mesh size of 0.1-0.4 mm, or cutting it into a strip structure with a width of 0.05-0.15 mm.

[0037] In this invention, in step (1), the inert atmosphere is selected from argon; when the metal material is copper, the melting temperature is 1100-1150℃; when the metal material is silver, the melting temperature is 960-1000℃; the standing time is 5-20min; the temperature of the spinneret is controlled to be 10-30℃ higher than the melting point of the metal material used; the cooling medium is selected from nitrogen or water mist, and the cooling rate is 100-1000℃ / s; the drawing speed for drawing and refining is 100-500m / min, and the drawing ratio is 10-200 times.

[0038] In this invention, step (1) further includes an annealing process for the obtained conductive core, wherein the annealing temperature is 200-280°C and lower than the recrystallization temperature of the corresponding metal material.

[0039] In this invention, in step (2), the number-average molecular weight (M) of PVB is... n The content of acetyl groups is 18-22 mol%, and the content of hydroxyl groups is 18-20 mol%. The plasticizer is selected from triethylene glycol diisooctanoate (3GO). The leveling agent is selected from polyether modified siloxane leveling agents (such as BYK-333 or TEGO Glide 410). The solvents include ethanol and ethyl acetate, and the mass ratio of ethanol to ethyl acetate is 0.5-1.5:0.5-1.5.

[0040] In this invention, the volume resistivity of the conductive preform is ≤3×10⁻⁶. -6 Ω·cm, tensile strength ≥280MPa, temperature range -40℃ to 140℃.

[0041] The volume resistivity was obtained according to GB / T 351-2019, and the tensile strength was obtained according to GB / T 228.1-2021.

[0042] In this invention, the PVB-based intermediate layer includes a buffer adapter layer and a main adhesive PVB layer. The buffer adapter layer is located between the first glass plate and the conductive preform, and the main adhesive PVB layer is located between the conductive preform and the second glass plate.

[0043] In this invention, a buffer adapter layer is used to alleviate the stress difference between the conductive preform and the main adhesive PVB layer; the thickness of the buffer adapter layer is 15-30 μm; the buffer adapter layer is a modified PVB layer containing nano-calcium carbonate; the particle size of the nano-calcium carbonate is 5-15 nm, and the content of nano-calcium carbonate in the buffer adapter layer is 0.3-0.8 wt%.

[0044] In this invention, in order to ensure the dispersion effect of nano-calcium carbonate in the buffer adapter layer, polyethylene glycol is added as a dispersant; the polyethylene glycol is selected from PEG4000.

[0045] In this invention, the method for preparing the buffer adapter layer includes the following steps: Weigh out the following components by weight: 100 parts PVB, 26-30 parts plasticizer, 0.3-0.8 parts nano calcium carbonate, and 0.045-0.16 parts dispersant; Nano-calcium carbonate and stearic acid are mixed at a mass ratio of 100:1.5-2.5 and mixed at 300-500 rpm for 15-30 minutes at 85-105℃ to obtain modified nano-calcium carbonate. The modified nano-calcium carbonate, dispersant, and 4-6 parts of plasticizer are sheared and dispersed at 55-65℃ for 25-35 minutes to form a uniform slurry. Then, the slurry is mixed with PVB and the remaining plasticizer in a high-speed mixer at 90-100℃ for 10-20 minutes to obtain a mixture. The mixture is melt-blended, underwater pelletized, and dried using a twin-screw extruder at 160-170℃ to obtain modified PVB masterbatch. Finally, the modified PVB masterbatch is melt-extruded using a single-screw casting extruder at 155-160℃, calendered by casting rollers (135-145℃), and cooled to 20-30℃ to form a buffer adapter layer.

[0046] In this invention, the intrinsic viscosity of PVB is 0.45-0.55 dL / g (ISO 1628-1), the acetyl content is 19-21 mol%, and the hydroxyl content is 18-20 mol%; the plasticizer is selected from triethylene glycol diisooctanoate (3GO).

[0047] In this invention, the main adhesive PVB layer is used to ensure adhesive strength; the thickness of the main adhesive PVB layer is 400-1600 μm; the content of plasticizer in the main adhesive PVB layer is 18-25 wt%; the plasticizer is selected from triethylene glycol diisooctanoate (3GO).

[0048] In this invention, the main adhesive PVB layer also includes an antioxidant, which is selected from antioxidant 1076; the content of the antioxidant in the main adhesive PVB layer is 0.1-0.3 wt%.

[0049] In this invention, the method for preparing the main adhesive PVB layer includes the following steps: Weigh out the following components by weight: 100 parts PVB, 18-25 parts plasticizer, and 0.1-0.3 parts antioxidant. Put the above components into a high-speed mixer and mix at 75-85℃ for 15-25 minutes until homogeneous. Then, melt-extrude the mixture through a single-screw extruder at 165-170℃. After passing through a filter (100-300 mesh), the mixture is cast onto a set of cooling rollers (surface temperature 10-20℃) through a coat hanger die to form the final product. At the same time, the surface is given a micro-roughness (Ra=2-3μm) by embossing rollers. Finally, the main adhesive PVB layer is formed.

[0050] In this invention, the intrinsic viscosity of PVB is 0.45-0.55 dL / g (ISO 1628-1), the acetyl content is 19-21 mol%, and the hydroxyl content is 18-20 mol%.

[0051] In this invention, the PVB-based intermediate layer further includes a functionally enhanced PVB layer, which is used to integrate additional functions; the thickness of the functionally enhanced PVB layer is 10-25 μm; the functionally enhanced PVB layer is located between the main adhesive PVB layer and the second glass plate.

[0052] In this invention, the functionally enhanced PVB layer contains additives selected from at least one of ultraviolet absorbers and infrared reflective particles; the ultraviolet absorber is selected from 2-hydroxy-4-methoxybenzophenone; and the infrared reflective particles are selected from nano-ATO.

[0053] In this invention, when the functionally enhanced PVB layer contains an ultraviolet absorber, its content is 3-8 wt%; when the functionally enhanced PVB layer contains infrared reflective particles, its content is 2-5 wt%.

[0054] In this invention, the method for preparing the functionally enhanced PVB layer includes the following steps: Weigh out the following components by weight: 100 parts PVB, 22-28 parts plasticizer, and 2-13 parts additives. Mix the above components and then melt-blend and extrude them into granules using a twin-screw extruder at 150-155°C. Then, melt-extrude the resulting granules using a precision casting machine at 145-155°C and cast them onto a cooling roller (surface temperature 15-25°C) for rapid cooling to form a functionally enhanced PVB layer.

[0055] In this invention, the intrinsic viscosity of PVB is 0.45-0.55 dL / g (ISO 1628-1), the acetyl content is 19-21 mol%, and the hydroxyl content is 18-20 mol%; the plasticizer is selected from triethylene glycol diisooctanoate (3GO).

[0056] In this invention, the functionally enhanced PVB layer is composited with the main adhesive PVB layer (by co-extrusion).

[0057] In this invention, during co-extrusion, two single-screw extruders are used to melt the materials of the main adhesive layer and the functional reinforcement layer respectively. The output volume ratio is controlled by a precision gear melt pump. After being stacked by a multi-layer co-extrusion distributor, the materials are extruded through a coat hanger-type flat die head (width 500-700mm). Then, the materials are cooled and shaped step by step by a three-roll cooling system (upper roll 20-30℃, middle roll 15-25℃, lower roll 10-20℃) to achieve two-layer composite.

[0058] In this invention, the extruder temperature of the main adhesive layer is set as follows: Zone 1 145-155℃, Zone 2 160-170℃, Zone 3 165-175℃, connector 165-175℃, and die 165-175℃; the extruder temperature of the functional reinforcement layer is set as follows: Zone 1 140-150℃, Zone 2 150-160℃, Zone 3 155-165℃, connector 155-165℃, and die 160-170℃.

[0059] The present invention also provides a method for preparing the PVB composite glass laminate with independent conductive structure, comprising the following steps: S1. The conductive preform is fixed in the PVB base intermediate layer by electrostatic adsorption; the first glass plate, the PVB base intermediate layer, and the second glass plate are stacked in the order of forming a pre-assembled body. S2. The pre-assembled body is subjected to vacuum pre-compression and hot-press curing treatment in sequence to obtain a PVB composite glass laminate with an independent conductive structure.

[0060] In this invention, S1 specifically includes: laying a buffer adapter layer on the surface of the first glass plate; then, using an electrostatic adsorption device, precisely fixing the conductive preform to the surface of the buffer adapter layer at a voltage of 4-8kV; next, covering the structure of the fixed conductive preform with a main adhesive PVB layer; if the PVB base intermediate layer includes a functionally enhanced PVB layer, then placing it between the main adhesive PVB layer and the second glass plate; finally, covering the second glass plate to form a pre-assembled body.

[0061] In this invention, the vacuum pre-compression process in S2 is as follows: vacuum degree 20-60 mbar, temperature 90-110℃, time 12-18 min; the hot-press curing process is as follows: temperature 120-140℃, pressure 10-14 bar, time 90-120 min.

[0062] In this invention, after the hot-pressing curing process is completed in S2, excess material at the edge of the laminate is cut off to obtain a PVB composite glass laminate with an independent conductive structure.

[0063] The following embodiments are provided to better understand the present invention and are not limited to the preferred embodiments described. They do not constitute a limitation on the content and scope of protection of the present invention. Any product that is the same as or similar to the present invention, derived by any person under the guidance of the present invention or by combining the features of the present invention with other prior art, falls within the protection scope of the present invention.

[0064] Where specific experimental steps or conditions are not specified in the examples, they can be performed according to the conventional experimental steps or conditions described in the literature in this field. Reagents or instruments whose manufacturers are not specified are all commercially available conventional reagent products.

[0065] Example 1 This embodiment provides a method for preparing a PVB composite glass laminate with an independent conductive structure, including the following steps: 1. Glass plate preparation: Float glass with a thickness of 4mm was selected as the first and second glass plates.

[0066] 2. Preparation of conductive preforms: The conductive core was prepared by melt spinning: Under argon protection, copper was melted at 1120℃, allowed to stand for 15 minutes, and then extruded through a spinneret (temperature 1140℃). The molten copper was cooled with nitrogen (cooling rate 500℃ / s) and drawn through traction rollers at a speed of 300m / min (drawing ratio 150 times) to obtain a copper core with a diameter of 8μm. This core was then annealed at 250℃. Finally, a dense silver plating layer (1μm thick) was formed on the surface of the copper core using a conventional electroplating process, resulting in a copper-silver composite metal core (i.e., the conductive core, with a diameter of 10μm).

[0067] Preparation of PVB coating solution: Weigh out 20% PVB (number average molecular weight 30,000, acetyl content 20 mol%, hydroxyl content 19 mol%), 0.3% silane coupling agent (KH560), 3% plasticizer (3GO), and 0.1% leveling agent (BYK-333) by mass percentage, with the balance being a mixed solvent of ethanol and ethyl acetate (mass ratio 1:1). Stir at 45℃ for 2.5 h, filter, and degas to obtain a PVB coating solution with a viscosity of 45 mPa·s (25℃).

[0068] Using a precision dip-coating method, the conductive core is passed through a coating liquid bath at a speed of 8 m / min, pre-baked at 80℃ for 2 min, cured at 120℃ for 5 min, and cooled at room temperature to form a uniform PVB coating layer (thickness of 3 μm), which is then cut into strips with a width of 0.1 mm.

[0069] The volume resistivity of the resulting conductive preform is 2.8 × 10⁻⁶.-6 Ω·cm, tensile strength of 305MPa, temperature range of -40℃ to 140℃.

[0070] 3. Preparation of the buffer adapter layer: Weigh out 100 parts of PVB (intrinsic viscosity 0.50 dL / g, acetyl content 20 mol%, hydroxyl content 19 mol%), 28 parts of plasticizer (3GO), 0.5 parts of nano calcium carbonate (particle size 5-15 nm), and 0.08 parts of dispersant (PEG4000). Nano-calcium carbonate and stearic acid were mixed at a mass ratio of 100:2 and mixed at 95°C and 400 rpm for 20 min to obtain modified nano-calcium carbonate. The modified nano-calcium carbonate, dispersant and 5 parts of plasticizer were sheared and dispersed at 60°C for 30 min to prepare a slurry. Then, the slurry, PVB and the remaining plasticizer were mixed at 95°C for 15 min and melt-blended, underwater pelletized and dried by a twin-screw extruder (165°C) to obtain modified PVB masterbatch. The masterbatch was extruded by a single-screw casting extruder (158°C), calendered by casting rollers at 140°C and cooled to 25°C to obtain a buffer adapter layer with a thickness of 20 μm.

[0071] 4. Preparation of composite PVB layer with main adhesive layer and functionally enhanced PVB layer: Main adhesive layer: Weigh 100 parts of PVB (intrinsic viscosity 0.50 dL / g, acetyl content 20 mol%, hydroxyl content 19 mol%), 22 parts of plasticizer (3GO), and 0.2 parts of antioxidant (1076). Mix at 80℃ for 20 min, extrude through a single screw extruder (168℃), filter through a 200-mesh filter, and then cast through a coat hanger die to a cooling roller (15℃) for forming. The surface is treated with an embossing roller (Ra=2.5μm) to form the main adhesive PVB layer with a thickness of 1000μm.

[0072] Functional reinforcement layer: Weigh 100 parts of PVB (intrinsic viscosity 0.50 dL / g, acetyl content 20 mol%, hydroxyl content 19 mol%), 25 parts of plasticizer (3GO), and 5 parts of UV absorber (2-hydroxy-4-methoxybenzophenone). Melt-blend and granulate the mixture using a twin-screw extruder (152℃), then extrude it using a precision casting machine (150℃) and cool it with a cooling roller (20℃) to obtain a functional reinforcement layer with a thickness of 15 μm.

[0073] Co-extrusion composite: The main adhesive layer and the functional reinforcement layer are melted separately by two single-screw extruders (the extruder temperature for the main adhesive layer is set as follows: Zone 1 150℃, Zone 2 165℃, Zone 3 170℃, connector 170℃, die 170℃; the extruder temperature for the functional reinforcement layer is set as follows: Zone 1 145℃, Zone 2 155℃, Zone 3 160℃, connector 160℃, die 165℃). The output ratio is controlled by a gear pump, and after being stacked by a multi-layer co-extrusion distributor, it is extruded through a coat hanger-type flat die (width 600mm). It is then cooled and shaped by a three-roll cooling system (upper roll 25℃, middle roll 20℃, lower roll 15℃) to obtain a composite of the main adhesive PVB layer and the functional reinforcement PVB layer.

[0074] 5. Laminate assembly and curing: A buffer adapter layer is laid flat on the surface of the first glass plate; then, using an electrostatic adsorption device, the conductive preform is precisely fixed to the surface of the buffer adapter layer at a voltage of 6kV; next, a composite of a main adhesive PVB layer and a functionally enhanced PVB layer (the functionally enhanced PVB layer is disposed between the main adhesive PVB layer and the second glass plate) and the second glass plate are covered on the structure of the fixed conductive preform to form a pre-assembled body.

[0075] The pre-assembled body was placed in a vacuum ring and kept at a vacuum of 40 mbar and a temperature of 100°C for 15 minutes to remove interlayer gas. Then it was transferred to an autoclave and hot-pressed at 130°C and 12 bar for 100 minutes. After curing, excess material at the edges was trimmed to obtain a PVB composite glass laminate with an independent conductive structure (PVB composite glass laminate for automotive side windows with integrated antenna function).

[0076] Example 2 This embodiment provides a method for preparing a PVB composite glass laminate with an independent conductive structure, including the following steps: 1. Glass plate preparation: Chemically strengthened glass with a thickness of 2.1 mm was selected as the first and second glass plates.

[0077] 2. Preparation of conductive preforms: Conductive cores are prepared by melt spinning: Silver is melted at 980°C under argon protection, allowed to stand for 15 minutes, and then extruded through a spinneret (temperature 1000°C). The core is cooled by water mist (cooling rate 800°C / s) and drawn by traction rollers at a speed of 400 m / min (drawing ratio 180 times) to obtain a metal core (i.e., conductive core) with a diameter of 12 μm. The core is then annealed at 280°C.

[0078] Preparation of PVB coating solution: Same as in Example 1.

[0079] Using a precision dip-coating method, the conductive core is passed through a coating liquid bath at a speed of 8m / min, pre-baked at 80℃ for 1.5min, cured at 120℃ for 5min, and cooled at room temperature to form a uniform PVB coating layer (2.5μm thick), which is then woven into a mesh structure with a mesh size of 0.2mm.

[0080] The volume resistivity of the resulting conductive preform is 2.5 × 10⁻⁶. -6 Ω·cm, tensile strength of 295MPa, temperature range of -40℃ to 140℃.

[0081] 3. Preparation of the buffer adapter layer: It is basically the same as in Example 1, except that "0.6 parts of nano calcium carbonate" and "the thickness of the buffer adapter layer is 25 μm" are modified.

[0082] 4. Preparation of the main adhesive PVB layer: The preparation process of the main adhesive layer is basically the same as that in Example 1, except that the following modifications are made: "the plasticizer is 20 parts" and "the thickness of the main adhesive PVB layer is 800 μm".

[0083] 5. Laminate assembly and curing: A buffer adapter layer is laid flat on the surface of the first glass plate; then, using an electrostatic adsorption device, the conductive preform is precisely fixed to the surface of the buffer adapter layer at a voltage of 6kV; next, the main adhesive PVB layer and the second glass plate are covered on the structure of the fixed conductive preform to form a pre-assembled body.

[0084] The pre-assembled body was placed in a vacuum ring and kept at a vacuum of 30 mbar and a temperature of 105°C for 12 minutes to remove interlayer gas. Then it was transferred to an autoclave and hot-pressed at 135°C and 13 bar for 110 minutes. After curing, excess material at the edges was trimmed to obtain a PVB composite glass laminate with an independent conductive structure (a PVB composite glass laminate for automotive windshields with integrated heating function, which can uniformly raise the glass surface temperature to above 35°C within 90 seconds after being connected to a 12V power supply).

[0085] Comparative Example 1 This comparative example provides a method for preparing a PVB composite glass laminate, comprising the following steps: 1. Glass plate preparation: Same as Example 2.

[0086] 2. Preparation of PVB intermediate layer: First PVB layer: 200μm thick, 3GO plasticizer content 12wt%; Second PVB layer: 600μm thick, 3GO plasticizer content 28wt%.

[0087] 3. Preparation of conductive patterns: On the surface of the first PVB layer, a conductive circuit pattern of silver paste is printed using a screen printing process, and then dried in an oven at 120°C for 15 minutes to cure the silver paste.

[0088] 4. Laminate assembly and curing: The layers are stacked in the following order: first glass plate, first PVB layer with printed circuit pattern (printed side up), second PVB layer, and second glass plate. After alignment, a pre-assembled assembly is formed.

[0089] The pre-assembled body was placed in a vacuum ring and kept at a vacuum of 30 mbar and a temperature of 105°C for 12 min to remove interlayer gas. Then it was transferred to an autoclave and hot-pressed at 135°C and 13 bar for 110 min. After curing, excess material at the edges was trimmed to obtain the PVB composite glass laminate.

[0090] Comparative Example 2 This comparative example provides a method for preparing a PVB composite glass laminate, comprising the following steps: 1. Glass plate preparation: Same as Example 2.

[0091] 2. Preparation of copper-clad PVB film: Take a rolled copper foil with a thickness of 18 μm and coat one side with a thermoplastic adhesive. The copper foil coated with adhesive is continuously bonded to the surface of a PVB film (thickness 800 μm, plasticizer 3GO content 22wt%) by passing it through a hot press roller at 125℃ and 0.8MPa pressure to form a copper-clad PVB film.

[0092] 3. Circuit pattern creation: Photoresist is coated onto the copper foil surface of a copper-clad PVB film, and then exposed and developed to form a circuit pattern mask. The unprotected copper foil is etched using ferric chloride etchant to remove residual photoresist, resulting in a PVB film with precision etched copper circuitry.

[0093] 4. Laminate assembly and curing: The PVB film with etched copper circuitry (circuit side up) is laid flat on the surface of the first glass plate, and then covered with the second glass plate. After alignment, a pre-assembled body is formed.

[0094] The pre-assembled body was placed in a vacuum ring and kept at a vacuum of 30 mbar and a temperature of 105°C for 12 min to remove interlayer gas. Then it was transferred to an autoclave and hot-pressed at 135°C and 13 bar for 110 min. After curing, excess material at the edges was trimmed to obtain the PVB composite glass laminate.

[0095] Experimental Example 1 The laminate samples prepared in Examples 1-2 and Comparative Examples 1-2 were subjected to comparative performance tests. The specific conditions and methods for each test are as follows: Initial adhesive strength was evaluated by peeling the sample edges using a 90° peel tester according to GB / T 2790 standard, with the maximum peel strength (MPa) measured. The adhesive strength test after boiling was conducted according to the enterprise standard to simulate an extreme humid and hot environment: the sample was completely immersed in distilled water at 60°C for 2 hours, removed and dried, and its strength was measured using the same peel test method as above. The stability of electrical conductivity was evaluated according to IEC 60068-2-1 and IEC 60068-2-2 standards. The sample was placed in a high and low temperature test chamber and subjected to 50 temperature cycles between -40°C and 80°C. The resistance value of the conductive circuit before and after the cycle was tested and its rate of change was calculated. The transmittance and haze were measured according to GB / T 2410 standard, using a spectrophotometer and a haze meter in the wavelength range of 380-780nm. The moisture resistance test was conducted according to GB / T 2423.3 standard. Samples were placed in a constant temperature and humidity chamber at 85℃ and 85% relative humidity for 500 hours. After the test, the appearance was checked for any abnormalities such as delamination, bubbles, or oxidation, and the conductivity was verified. Production efficiency was assessed using a statistical method, calculating the average number of qualified products (pieces / shift) produced in one standard work shift (8 hours) on a standardized production line. Material loss rate was also assessed using a statistical method, calculating the percentage of intermediate layer material scrap due to process errors (such as incorrect positioning or damage to the conductive structure) out of the total input weight. The test results are recorded in Table 1.

[0096] Table 1 Test Results

[0097] As shown in Table 1, in terms of adhesive performance, the initial adhesive strength and the adhesive strength after boiling water of the two embodiments of the present invention are significantly better than those of the two comparative examples. In particular, after boiling water testing, the strength retention rate of the embodiments is extremely high (e.g., 98.75% for Example 1), which proves that the present invention, through its unique interlayer structure and interface design, can effectively resist moisture erosion and possess excellent water resistance and long-term structural stability. In terms of conductivity stability, after 50 high and low temperature cycles, the resistance change rate of the embodiments is much lower than that of the comparative examples (Example 2 is only +1.8%). This indicates that the "conductive core-polymer coating layer" independent preform structure adopted in the present invention, combined with a matching buffer layer, can effectively absorb and alleviate thermal stress, thereby avoiding fatigue damage or breakage of the conductive path. In terms of optical performance, the embodiments of the present invention, while successfully integrating conductivity and other functions, still maintain high light transmittance and low haze, exhibiting excellent optical quality and fully meeting the stringent requirements of automotive glass for visual clarity. Regarding environmental reliability, after rigorous high-temperature and high-humidity testing, the products of this invention (Examples 1 and 2) maintained their appearance and conductivity intact, while Comparative Example 1 showed edge delamination, and Comparative Example 2 experienced circuit oxidation. This further confirms the weather resistance advantages of this invention in terms of structural design and material system. In terms of production and economy, the solutions of this invention (Examples) exhibit higher production efficiency and lower material loss rate. This is due to the prefabrication of the independent conductive preforms and the simplification of the overall process, avoiding the problem of entire film scrapping caused by local defects resulting from the bonding processing of the conductive structure and PVB film in traditional solutions.

[0098] Therefore, the present invention adopts a PVB composite glass laminate with an independent conductive structure as described above. By adopting the innovative design of "setting an independent conductive preform in the PVB base intermediate layer", it systematically solves a series of problems in the prior art, such as poor compatibility between the conductive structure and the PVB layer, low long-term reliability, complex process and high cost, while retaining the advantages of high adhesion and high light transmittance of the PVB intermediate layer.

[0099] Finally, it should be noted that the above embodiments are merely illustrative examples for clear explanation and are not intended to limit the implementation. Those skilled in the art will recognize that other variations or modifications can be made based on the above description. It is neither necessary nor possible to exhaustively list all possible implementations here. However, obvious variations or modifications derived therefrom are still within the scope of protection of this invention.

Claims

1. A PVB composite glass laminate with an independent conductive structure, characterized in that, It includes a first glass plate, a PVB-based intermediate layer, and a second glass plate stacked sequentially; the PVB-based intermediate layer contains an independent conductive preform.

2. The PVB composite glass laminate with an independently conductive structure according to claim 1, characterized in that, The conductive preform includes a conductive core and a PVB layer covering the outer surface of the conductive core.

3. The PVB composite glass laminate with an independently conductive structure according to claim 2, characterized in that, The conductive core is made of metal and has an equivalent diameter of 0.05-20 μm; the PVB layer has a thickness of 2-4 μm.

4. The PVB composite glass laminate with an independently conductive structure according to claim 2 or 3, characterized in that, The PVB layer contains a silane coupling agent; the content of the silane coupling agent in the PVB layer is 0.2-0.4 wt%.

5. The PVB composite glass laminate with an independently conductive structure according to claim 1, characterized in that, The PVB base intermediate layer includes a buffer adapter layer and a main adhesive PVB layer. The buffer adapter layer is located between the first glass plate and the conductive preform, and the main adhesive PVB layer is located between the conductive preform and the second glass plate.

6. The PVB composite glass laminate with an independently conductive structure according to claim 5, characterized in that, The buffer adapter layer is a modified PVB layer containing nano-calcium carbonate; the content of nano-calcium carbonate in the buffer adapter layer is 0.3-0.8 wt%.

7. The PVB composite glass laminate with an independently conductive structure according to claim 5, characterized in that, The plasticizer content in the main adhesive PVB layer is 18-25 wt%.

8. The PVB composite glass laminate with an independently conductive structure according to claim 5, characterized in that, The PVB base intermediate layer also includes a functionally enhanced PVB layer, which is located between the main adhesive PVB layer and the second glass plate.

9. A method for preparing a PVB composite glass laminate with an independent conductive structure according to any one of claims 1-8, characterized in that, Includes the following steps: S1. The conductive preform is fixed in the PVB base intermediate layer by electrostatic adsorption; the first glass plate, the PVB base intermediate layer, and the second glass plate are stacked in the order of forming a pre-assembled body. S2. The pre-assembled body is subjected to vacuum pre-compression and hot-press curing treatment in sequence to obtain a PVB composite glass laminate with an independent conductive structure.

10. The preparation method according to claim 9, characterized in that, In S2, the process conditions for vacuum pre-compression are: vacuum degree 20-60 mbar, temperature 90-110℃, time 12-18 min; the process conditions for hot-press curing are: temperature 120-140℃, pressure 10-14 bar, time 90-120 min.

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