Full-wave-band heat shielding modified PVB (polyvinyl butyral) composite film as well as preparation method and application thereof

Abstract

The invention relates to the technical field of PVB (polyvinyl butyral) films, in particular to a full-wave-band heat-shielding modified PVB composite film as well as a preparation method and application thereof. The full-band heat shielding modified PVB composite film provided by the invention is of an asymmetric structure and comprises a modified PVB matrix and a heat shielding coating covering one side of the modified PVB matrix, the modified PVB matrix is prepared from the following components: polyvinyl butyral and an epoxy silane coupling agent; the heat shielding coating comprises the following components: CsWO3 nano powder, ZnO nano powder, water-based acrylic resin and a composite dispersion system; the composite dispersion system comprises triethylene glycol di-2-ethylhexoate, polyvinylpyrrolidone and diethylene glycol monobutyl ether. The full-wave-band heat shielding modified PVB composite film provided by the invention can realize 780-2500nm full-wave-band near-infrared high-efficiency barrier, improve the binding force and performance stability of a heat shielding coating, and meet the production requirements of light weight, environmental protection and industrialization at the same time.

Description

Technical Field

[0001] This invention relates to the field of PVB film technology, and in particular to a full-band heat-shielding modified PVB composite film, its preparation method, and its application. Background Technology

[0002] PVB film is a core component of automotive glass, and its heat shielding performance directly affects in-vehicle temperature regulation and air conditioning energy consumption. Currently, there are three main technical routes for manufacturing heat shielding PVB films for automobiles: coating-type heat shielding PVB films absorb near-infrared radiation by coating the surface with a single material such as ATO or ITO; particle blend-type heat shielding PVB films blend ATO and CsWO3 nanoparticles into the PVB matrix to block near-infrared radiation; and metal-layer composite heat shielding PVB films embed an extremely thin metal layer to reflect near-infrared radiation, which is mostly used in high-end models.

[0003] However, the above-mentioned heat shielding PVB film still has some problems: (1) The heat shielding band is not comprehensive, covering only the 780~1800nm ​​mid-short wave near infrared, and the blocking rate of the 1800~2500nm long wave near infrared is less than 50%, which makes it difficult to control the deep temperature rise inside the car in summer; (2) The coating reliability is poor, mostly physical bonding, with a bonding force of only 1.2~1.8MPa. After 50 cold and hot cycles, the peeling rate is greater than 15%, and the performance decay exceeds 30%; (3) Optical and blocking are unbalanced. Some methods increase the coating thickness or particle addition to improve the blocking rate, resulting in insufficient light transmittance. The reflective glare rate of the metal layer composite heat shielding PVB film is too high, affecting the driver's vision; (4) The structural adaptability is insufficient. The thickness of some composite structure films exceeds 0.7mm, which conflicts with the demand for lightweight and energy-saving new energy vehicles and increases the difficulty of glass forming; (5) The dispersion system has poor stability. Traditional water-ethanol solvents are prone to nanoparticle agglomeration, affecting the consistency of heat shielding performance.

[0004] Therefore, developing a heat-shielding PVB film that provides full-band heat shielding, stable performance, and meets lightweight requirements is of great significance to the development of this field. Summary of the Invention

[0005] The purpose of this invention is to provide a full-band heat-shielding modified PVB composite film, its preparation method, and its application. The full-band heat-shielding modified PVB composite film provided by this invention can achieve efficient near-infrared blocking in the 780~2500nm full-band, improve the adhesion and performance stability of the heat-shielding coating, and at the same time meet the requirements of lightweight, environmental protection, and industrial production.

[0006] To achieve the above objectives, this invention provides a full-band heat-shielding modified PVB composite film. The full-band heat-shielding modified PVB composite film has an asymmetric structure, comprising a modified PVB matrix and a heat-shielding coating covering one side of the modified PVB matrix. The modified PVB matrix comprises polyvinyl butyral and an epoxy silane coupling agent. The heat-shielding coating comprises CsWO3 nanopowder, ZnO nanopowder, water-based acrylic resin, and a composite dispersion system. The composite dispersion system comprises triethylene glycol diisooctanoate (3G8), polyvinylpyrrolidone (PVP), and diethylene glycol monobutyl ether (anti-whitening agent). The total thickness of the full-band heat-shielding modified PVB composite film is 0.38A mm, where A is a positive integer.

[0007] Preferably, the thickness of the heat shielding coating is 30~50μm.

[0008] Preferably, in the modified PVB matrix, the epoxy silane coupling agent accounts for 0.3~0.8 wt% of the mass of polyvinyl butyral; the epoxy silane coupling agent includes one or more of γ-glycidyl etheroxypropyltrimethoxysilane (KH560), γ-glycidyl etheroxypropyltriethoxysilane (KH561), and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane (KH562); the polyvinyl butyral includes Kuraray Mowital® B60H; and the polyvinyl alcohol (PVOH) content of Kuraray Mowital® B60H is 18~20 wt%.

[0009] Preferably, the heat shielding coating comprises 12-15 wt% CsWO3 nanopowder, 3-5 wt% ZnO nanopowder, 20-25 wt% waterborne acrylic resin, and 55-65 wt% composite dispersion system; based on the total mass of the heat shielding coating as 100 wt%, the composite dispersion system comprises 5-10 wt% triethylene glycol diisooctanoate, 1-3 wt% polyvinylpyrrolidone, and 45-55 wt% diethylene glycol monobutyl ether.

[0010] Preferably, the CsWO3 nanoparticles have a D 50 The particle size is 20~30nm; the D of the ZnO nanopowder 50 The particle size is 10~20nm.

[0011] This invention also provides a method for preparing the full-band thermally shielding modified PVB composite film described above, comprising the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and epoxy silane coupling agent are mixed at high speed and then subjected to twin-screw extrusion and cooling to obtain modified PVB matrix; the dispersion uniformity of epoxy silane coupling agent in the modified PVB matrix is ​​≥95%; The high-speed mixing is a stirring mixing, and the stirring speed is 1200~1500 r / min; S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are premixed with a twin-screw extruder to obtain a premix. Then the premix and the composite dispersion system are ultrasonically dispersed and milled in sequence to obtain the heat shield coating slurry. The rotational speed of the twin-screw premixer is 100~150 r / min; S3. Coating and curing: The heat shielding coating slurry is coated on one side of the modified PVB substrate to obtain a wet film. Then the wet film is dried and cured in sequence to obtain the full-band heat shielding modified PVB composite film. There is no requirement for the time order of steps S1 and S2.

[0012] Preferably, the mixing time in S1 is 10-15 min; the temperature range of the twin-screw extrusion includes: zone 1 150-155℃, zone 2 160-165℃, zone 3 170-175℃ and die head 165-170℃; the screw speed of the twin-screw extrusion is 250-300 r / min; the cooling and shaping is achieved by traction with a 25-30℃ cooling roller.

[0013] Preferably, the twin-screw premixing time in S2 is 5-8 min; the ultrasonic dispersion power is 700-1000 W, and the time is 25-35 min; the sand milling is performed using zirconium beads with a diameter of 0.1-0.2 mm, and the sand milling time is 25-35 min; the viscosity of the heat shield coating slurry is 200-300 mPa·s, and the particle size uniformity is ≥92%.

[0014] Preferably, the coating speed in S3 is 3~4 m / min; the thickness of the wet film is 80~100 μm; the drying temperature is 50~70℃ and the holding time is 12~18 min; the curing temperature is 100~120℃ and the holding time is 40~50 min.

[0015] The present invention also provides the application of the full-band heat-shielding modified PVB composite film described above, wherein the full-band heat-shielding modified PVB composite film is applied in automotive glass, building energy-saving glass or new energy equipment windows.

[0016] This invention provides a full-band thermally shielding modified PVB composite film, its preparation method, and its application, achieving the following beneficial effects: (1) The full-band thermal shielding PVB composite film provided by the present invention achieves full-band near-infrared blocking of 780~2500nm through the synergistic effect of CsWO3 nanopowder (long-wave blocking) and ZnO nanopowder (medium and short-wave blocking), and controls the blocking rate fluctuation of the full-band 780~2500nm to ≤2%. At the same time, it also stably maintains the blocking rate of long-wave near-infrared of 1800~2500nm at ≥85%, thus solving the problems of insufficient long-wave blocking and large performance fluctuation.

[0017] (2) This invention replaces the traditional water-ethanol solvent with a composite dispersion system (triethylene glycol diisooctanoate, polyvinylpyrrolidone and diethylene glycol monobutyl ether), which solves the problem of immiscibility between triethylene glycol diisooctanoate and ethanol. PVP plays a role in dispersion and stabilization, and diethylene glycol monobutyl ether achieves uniform compatibility between triethylene glycol diisooctanoate and other components, effectively inhibiting the aggregation of nanoparticles and improving the uniformity of light transmission and long-term stability of the coating.

[0018] (3) The total thickness of the full-band heat shield modified PVB composite film provided by the present invention strictly follows the integer multiple of 0.38mm, which is suitable for the lightweight requirements of new energy vehicles and reduces the weight by more than 40% compared with existing thick films. The light transmittance of the full-band heat shield modified PVB composite film provided by the present invention is ≥87.8% and the reflective glare rate is ≤2.7%, which meets the requirements for use in automotive windshields.

[0019] (4) This invention achieves uniform dispersion of epoxy silane coupling agent in modified PVB matrix (dispersion uniformity ≥95%) by combining high-speed mixing with twin-screw extrusion. The epoxy groups are evenly distributed, providing uniform chemical bonding sites for the heat shield coating, and solving the problem of coating adhesion fluctuation caused by local agglomeration of coupling agent in single-screw process.

[0020] (5) This invention achieves preliminary dispersion by using a twin-screw low-speed mixer without damaging the nanoparticle morphology of CsWO3 nanoparticles and ZnO nanoparticles, reducing the time of subsequent ultrasonication and sand milling (10-15 min shorter than the traditional process), reducing energy consumption, and improving the stability and performance consistency of the full-band heat shield modified PVB composite film; the output is increased by 30-40% compared with the traditional single-screw process, and the energy consumption per unit product is reduced by 15%, making it more suitable for industrial production. Detailed Implementation

[0021] Unless otherwise defined, the technical or scientific terms used in this invention shall have the ordinary meaning as understood by one of ordinary skill in the art to which this invention pertains.

[0022] This invention provides a full-band heat-shielding modified PVB composite film. The full-band heat-shielding modified PVB composite film has an asymmetric structure, comprising a modified PVB matrix and a heat-shielding coating covering one side of the modified PVB matrix. The modified PVB matrix comprises polyvinyl butyral and an epoxy silane coupling agent. The heat-shielding coating comprises CsWO3 nanopowder, ZnO nanopowder, water-based acrylic resin, and a composite dispersion system. The composite dispersion system comprises triethylene glycol diisooctanoate, polyvinylpyrrolidone, and diethylene glycol monobutyl ether. The total thickness of the full-band heat-shielding modified PVB composite film is 0.38A mm, where A is a positive integer.

[0023] In this invention, the total thickness of the full-band heat-shielding modified PVB composite film is 0.38A mm, where A is a positive integer; specifically, A is preferably 1, 2, 3, 4, 5, 6, 7 or 8.

[0024] In this invention, the total thickness of the full-band heat-shielding modified PVB composite film is preferably 0.38 mm (A is 1) or 0.76 mm (A is 2).

[0025] In this invention, when the total thickness of the full-band heat-shielding modified PVB composite film is 0.38 mm, the thickness of the modified PVB substrate is 0.33~0.35 mm; when the total thickness of the full-band heat-shielding modified PVB composite film is 0.76 mm, the thickness of the modified PVB substrate is 0.71~0.73 mm.

[0026] The full-band heat-shielding modified PVB composite film provided by the present invention includes a modified PVB matrix; the components of the modified PVB matrix include polyvinyl butyral and epoxy silane coupling agent.

[0027] In this invention, the polyvinyl butyral preferably includes Kuraray Mowital® B60H; the PVOH content of Kuraray Mowital® B60H is preferably 18~20wt%.

[0028] In this invention, the epoxy silane coupling agent preferably includes one or more of KH560, KH561 and KH562.

[0029] In this invention, the mass of the epoxy silane coupling agent in the modified PVB matrix is ​​preferably 0.3 to 0.8 wt% of the mass of polyvinyl butyral, more preferably 0.5 to 0.6 wt%.

[0030] The modified PVB matrix in this invention is modified with an epoxy silane coupling agent, which can provide chemical bonding sites for the heat shield coating and maintain the adhesion strength with the glass.

[0031] The full-band heat-shielding modified PVB composite film provided by the present invention includes a heat-shielding coating covering one side of the modified PVB substrate; the components of the heat-shielding coating include CsWO3 nanopowder, ZnO nanopowder, water-based acrylic resin and a composite dispersion system; the composite dispersion system includes triethylene glycol diisooctanoate, polyvinylpyrrolidone and diethylene glycol monobutyl ether.

[0032] In this invention, the heat shielding coating preferably comprises 12-15 wt% CsWO3 nanopowder, more preferably 13-14 wt%, 3-5 wt% ZnO nanopowder, more preferably 4 wt%, 20-25 wt% waterborne acrylic resin, more preferably 23 wt%, and a composite dispersion system of 55-65 wt%, more preferably 60 wt%.

[0033] In this invention, the D of the CsWO3 nanopowder 50 The particle size is preferably 20~30nm, more preferably 24~27nm.

[0034] In this invention, the D of the ZnO nanopowder 50 The particle size is preferably 10~20nm, more preferably 15~18nm.

[0035] In this invention, the solid content of the waterborne acrylic resin is preferably 30%.

[0036] In this invention, based on the total mass of the heat shielding coating being 100 wt%, the composite dispersion system preferably includes 5-10 wt% triethylene glycol diisooctanoate, more preferably 7-8 wt%, 1-3 wt% polyvinylpyrrolidone, more preferably 2 wt%, and 45-55 wt% diethylene glycol monobutyl ether, more preferably 50 wt%.

[0037] In this invention, the polyvinylpyrrolidone preferably includes polyvinylpyrrolidone-K30.

[0038] In this invention, the thickness of the heat shielding coating is preferably 30~50μm, more preferably 40μm.

[0039] In the heat shielding coating of this invention, CsWO3 nanopowder absorbs long-wave near-infrared radiation in the range of 1800-2500 nm, while ZnO nanopowder absorbs mid-to-short-wave near-infrared radiation in the range of 780-1800 nm, and inhibits the agglomeration of CsWO3 nanopowder. The two work synergistically to achieve full-band near-infrared blocking in the range of 780-2500 nm. Waterborne acrylic resin, as a binder carrier, undergoes a cross-linking reaction with the epoxy groups of the modified PVB matrix to form stable -COC- chemical bonds, thereby improving the adhesion of the heat shielding coating. The composite dispersion system in this invention can ensure the uniform compatibility of each component and improve dispersion stability.

[0040] This invention also provides a method for preparing the full-band thermally shielding modified PVB composite film described above, comprising the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and epoxy silane coupling agent are mixed at high speed and then subjected to twin-screw extrusion and cooling to obtain modified PVB matrix; the dispersion uniformity of epoxy silane coupling agent in the modified PVB matrix is ​​≥95%; The high-speed mixing is a stirring mixing, and the stirring speed is 1200~1500 r / min; S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are premixed with a twin-screw extruder to obtain a premix. Then the premix and the composite dispersion system are ultrasonically dispersed and milled in sequence to obtain the heat shield coating slurry. The rotational speed of the twin-screw premixer is 100~150 r / min; S3. Coating and curing: The heat shielding coating slurry is coated on one side of the modified PVB substrate to obtain a wet film. Then the wet film is dried and cured in sequence to obtain the full-band heat shielding modified PVB composite film. There is no requirement for the time order of steps S1 and S2.

[0041] In this invention, polyvinyl butyral and epoxy silane coupling agent are mixed at high speed and then subjected to twin-screw extrusion and cooling to obtain a modified PVB matrix; the dispersion uniformity of the epoxy silane coupling agent in the modified PVB matrix is ​​≥95%.

[0042] In this invention, the high-speed mixing device preferably includes a high-speed mixer; the high-speed mixing speed is 1200~1500 r / min, preferably 1300~1400 r / min, and the mixing time is preferably 10~15 min, more preferably 12 min.

[0043] In this invention, the twin-screw extrusion equipment preferably includes a twin-screw extruder; the temperature range of the twin-screw extrusion preferably includes: zone 1 150~155℃, zone 2 160~165℃, zone 3 170~175℃ and die head 165~170℃; the screw speed of the twin-screw extrusion is preferably 250~300 r / min, more preferably 270 r / min.

[0044] In this invention, the cooling and shaping process preferably employs a 25-30°C cooling roller traction method.

[0045] This invention involves premixing CsWO3 nanopowder, ZnO nanopowder, and water-based acrylic resin using a twin-screw extruder to obtain a premix. The premix and the composite dispersion system are then subjected to ultrasonic dispersion and sand milling in sequence to obtain a heat-shielding coating slurry.

[0046] In this invention, the twin-screw premix preferably includes the following steps: adding CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin to the side feeding system of a twin-screw extruder for twin-screw premixing.

[0047] In this invention, the rotational speed of the twin-screw premix is ​​100~150 r / min, preferably 120 r / min, and the mixing time is preferably 5~8 min, more preferably 6~7 min.

[0048] In this invention, the ultrasonic dispersion device preferably includes a dispersion tank; the ultrasonic dispersion power is preferably 700~1000W, more preferably 800~900W, and the ultrasonic dispersion time is preferably 25~35min, more preferably 30min.

[0049] In this invention, the sand milling preferably uses zirconium beads; the diameter of the zirconium beads is preferably 0.1~0.2mm; the sand milling time is preferably 25~35min, more preferably 30min.

[0050] In this invention, the viscosity of the heat shield coating slurry is 200~300 mPa·s, and the particle size uniformity is ≥92%.

[0051] After obtaining the modified PVB substrate and the heat shielding coating slurry, the present invention coats the heat shielding coating slurry onto one side of the modified PVB substrate to obtain a wet film, and then the wet film is dried and cured sequentially to obtain the full-band heat shielding modified PVB composite film.

[0052] In this invention, the coating is preferably performed using a slit die; the coating speed is preferably 3~4 m / min, more preferably 3.5 m / min.

[0053] In this invention, the thickness of the wet film is preferably 80~100μm, more preferably 90μm.

[0054] In this invention, the drying temperature is preferably 50~70℃, and the heat preservation time is preferably 12~18min.

[0055] In this invention, the curing temperature is preferably 100~120℃, more preferably 110℃, and the heat preservation time is preferably 40~50min, more preferably 45min.

[0056] In this invention, the curing process preferably includes cooling the resulting product; the cooling is preferably natural cooling.

[0057] This invention reduces the thickness deviation of the modified PVB matrix through precise segmented temperature control and uniform shearing action using a twin-screw extruder. At the same time, the uniform dispersion of nanoparticles (CsWO3 nanoparticles and ZnO nanoparticles) avoids optical inhomogeneity caused by agglomeration, ensuring the consistency of the optical performance of the full-band heat-shielding modified PVB composite film.

[0058] The present invention also provides the application of the full-band heat-shielding modified PVB composite film described above, wherein the modified PVB composite film is applied in automotive glass, building energy-saving glass or new energy equipment windows.

[0059] The present invention will be further described below with reference to embodiments. The features mentioned above or in the specific embodiments of the present invention can be combined arbitrarily. These specific embodiments are only used to illustrate the present invention and are not intended to limit the scope of the present invention.

[0060] Example 1 This embodiment prepares a full-band heat-shielding modified PVB composite film. The full-band heat-shielding modified PVB composite film has an asymmetric structure, including a modified PVB matrix, and a heat-shielding coating is coated on one side of the modified PVB matrix.

[0061] In this embodiment, the total thickness of the full-band heat-shielding modified PVB composite film is 0.38 mm, of which the thickness of the heat-shielding coating is 30 μm.

[0062] The modified PVB matrix in this embodiment consists of Kuraray Mowital® B60H (PVOH content of 18wt%) and KH560 accounting for 0.3wt% of polyvinyl butyral by mass; the thickness of the modified PVB matrix is ​​0.35mm.

[0063] The heat shielding coating in this embodiment comprises D. 50 12wt% CsWO3 nanoparticles with a particle size of 20nm, D 50 The mixture consists of 3wt% ZnO nanopowder with a particle size of 10nm, 20wt% waterborne acrylic resin with a solid content of 30%, and 65wt% composite dispersion system. In the composite dispersion system, 3G8 accounts for 5wt%, PVP (molecular weight K30) accounts for 1wt%, and large anti-whitening accounts for 59wt%.

[0064] The preparation method of the full-band heat-shielding modified PVB composite film in this embodiment, with the raw materials used in the above proportions, includes the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and KH560 were premixed in a high-speed mixer at a speed of 1200 r / min for 10 min; then extruded through a twin-screw extruder. The temperature range of the twin-screw extruder was set as follows: Zone 1 150℃, Zone 2 160℃, Zone 3 170℃, and Die 165℃, with a screw speed of 250 r / min; finally, the modified PVB matrix (KH560 dispersion uniformity 95%) was obtained by traction shaping using a 25℃ cooling roller.

[0065] S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are added to the side feeding system of a twin-screw extruder and mixed at 100 r / min for 5 min. The mixture is then transferred to a dispersion tank and a composite dispersion system of 3G8, PVP and large anti-whitening agent is added. The mixture is ultrasonically dispersed at 700 W for 25 min. Then, it is milled with zirconia beads with a diameter of 0.1 mm for 25 min to obtain a heat shield coating slurry with a viscosity of 200 mPa·s and a particle size uniformity of ≥92%.

[0066] S3. Coating and Curing: Using a slit die, the heat shielding coating slurry is coated onto one side of the modified PVB substrate at a speed of 3 m / min to obtain a wet film with a thickness of 80 μm. Then, it is dried at 50℃ for 12 min, cured at 100℃ for 40 min, and naturally cooled to obtain a full-band heat shielding modified PVB composite film.

[0067] Example 2 This embodiment prepares a full-band heat-shielding modified PVB composite film. The full-band heat-shielding modified PVB composite film has an asymmetric structure, including a modified PVB matrix, and a heat-shielding coating is coated on one side of the modified PVB matrix.

[0068] In this embodiment, the total thickness of the full-band heat-shielding modified PVB composite film is 0.38 mm, and the thickness of the heat-shielding coating is 40 μm.

[0069] The modified PVB matrix in this embodiment consists of Kuraray Mowital® B60H (PVOH content of 19wt%) and KH561 accounting for 0.6wt% of polyvinyl butyral by mass; the thickness of the modified PVB matrix is ​​0.34mm.

[0070] The heat shielding coating in this embodiment comprises D. 50 13wt% CsWO3 nanoparticles with a particle size of 25nm, D 50 The mixture consists of 4 wt% ZnO nanopowder with a particle size of 15 nm, 23 wt% waterborne acrylic resin with a solid content of 30%, and 60 wt% composite dispersion system. In the composite dispersion system, 8 wt% 3G8, 2 wt% PVP (molecular weight K30), and 50 wt% large-scale anti-whitening agent.

[0071] The preparation method of the full-band heat-shielding modified PVB composite film in this embodiment, with the raw materials used in the above proportions, includes the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and KH561 were premixed in a high-speed mixer at a speed of 1350 r / min for 13 min; then extruded through a twin-screw extruder. The temperature range of the twin-screw extruder was set as follows: Zone 1 152℃, Zone 2 162℃, Zone 3 172℃ and Die 168℃, and the screw speed was 280 r / min; finally, the modified PVB matrix (KH561 dispersion uniformity 96%) was obtained by traction shaping using a 28℃ cooling roller.

[0072] S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are added to the side feeding system of a twin-screw extruder and mixed at 125 r / min for 6 min. The mixture is then transferred to a dispersion tank and a composite dispersion system of 3G8, PVP and large anti-whitening agent is added. The mixture is ultrasonically dispersed at 850 W for 30 min. Then it is milled with zirconia beads with a diameter of 0.2 mm for 30 min to obtain a heat shield coating slurry with a viscosity of 250 mPa·s and a particle size uniformity of ≥92%.

[0073] S3. Coating and Curing: Using a slit die, the heat shielding coating slurry is coated onto one side of the modified PVB substrate at a speed of 4 m / min to obtain a wet film with a thickness of 90 μm. Then, it is dried at 60℃ for 15 min, cured at 110℃ for 45 min, and naturally cooled to obtain a full-band heat shielding modified PVB composite film.

[0074] Example 3 This invention provides a full-band heat-shielding modified PVB composite film. The modified PVB composite film has an asymmetric structure, including a modified PVB matrix, and a heat-shielding coating is coated on one side of the modified PVB matrix.

[0075] In this embodiment, the total thickness of the full-band heat-shielding modified PVB composite film is 0.76 mm, and the thickness of the heat-shielding coating is 50 μm.

[0076] The modified PVB matrix in this embodiment consists of Kuraray Mowital® B60H (PVOH content of 20wt%) and KH562 accounting for 0.8wt% of polyvinyl butyral by mass; the thickness of the modified PVB matrix is ​​0.71mm.

[0077] The components of the heat shielding coating include D 50 15wt% CsWO3 nanoparticles with a particle size of 30nm, D 50The mixture consists of 5wt% ZnO nanopowder with a particle size of 20nm, 25wt% waterborne acrylic resin with a solid content of 30%, and 55wt% composite dispersion system. In the composite dispersion system, 10wt% 3G8, 3wt% PVP (molecular weight K30), and 42wt% large-scale anti-whitening agent.

[0078] The preparation method of the full-band heat-shielding modified PVB composite film in this embodiment, with the raw materials used in the above proportions, includes the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and KH562 were premixed in a high-speed mixer at a speed of 1500 r / min for 15 min; then extruded through a twin-screw extruder. The temperature range of the twin-screw extruder was set as follows: Zone 1 155℃, Zone 2 165℃, Zone 3 175℃ and Die 170℃, and the screw speed was 300 r / min; finally, the modified PVB matrix was obtained by traction shaping with a 30℃ cooling roller.

[0079] S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are added to the side feeding system of a twin-screw extruder and mixed at 150 r / min for 8 min. The mixture is then transferred to a dispersion tank and a composite dispersion system of 3G8, PVP and large anti-whitening agent is added. The mixture is ultrasonically dispersed at 1000W for 35 min. Then, it is milled with zirconia beads with a diameter of 0.2 mm for 35 min to obtain a heat shield coating slurry with a viscosity of 300 mPa·s and a particle size uniformity of ≥92%.

[0080] S3. Coating and Curing: Using a slit die, the heat shielding coating slurry is coated onto one side of the modified PVB substrate at a speed of 4 m / min to obtain a wet film with a thickness of 100 μm. Then, it is dried at 70℃ for 18 min, cured at 120℃ for 50 min, and naturally cooled to obtain a full-band heat shielding modified PVB composite film.

[0081] Comparative Example 1 The preparation method of this comparative example is the same as that of Example 2, except that the composition of the heat-shielding coating is adjusted as follows: D 50 The mixture contains 17wt% CsWO3 nanoparticles with a particle size of 25nm, 23wt% waterborne acrylic resin with a solid content of 30%, and a 60wt% composite dispersion system (8wt% 3G8, 2wt% PVP, and 50wt% large anti-whitening agent), and does not contain ZnO nanoparticles.

[0082] Comparative Example 2 The preparation method of this comparative example is the same as that of Example 2, except that the modified PVB matrix is ​​prepared by single-screw extrusion with a single screw speed of 200 r / min. The preparation of the heat shield coating omits the "pre-dispersion in the side feeding system of the twin-screw extruder" and directly adds each component to the dispersion tank.

[0083] Comparative Example 3 The preparation method of this comparative example is the same as that of Example 2, except that the modified PVB matrix uses only Kuraray Mowital® B60H (PVOH content 19wt%) and does not contain epoxy silane coupling agent.

[0084] Comparative Example 4 The preparation method of this comparative example is the same as that of Example 2, except that the composite dispersion system of the heat shield coating is replaced with deionized water and ethanol in a volume ratio of 1:1, and 3G8, PVP and large anti-white are not used.

[0085] Test Example 1 The full-band heat-shielding modified PVB composite films prepared in Examples 1-3 and Comparative Examples 1-4 were cut into test samples for performance testing.

[0086] (1) Near-infrared blocking rate and fluctuation amplitude test: The test was conducted according to GB / T2680 "Test Methods for Solar and Optical Performance of Architectural Glass". The test wavelength range covered 780~2500nm, and the scanning interval was set to 10nm. The blocking rate data for the 780~1800nm ​​(medium and short waves) and 1800~2500nm (long waves) bands were recorded respectively. The fluctuation range of the blocking rate across the entire band was calculated by "(maximum blocking rate within the band - minimum blocking rate) / average blocking rate of the band × 100%". Each sample was tested three times, and the average value was taken. The results are shown in Table 1.

[0087] (2) Adhesion test of heat shielding coating: The adhesion test of the heat shielding coating was conducted according to GB / T9286-1998 "Cross-cut Test for Paints and Varnishes". A cross-cut rating was applied, using a 1mm-pitch cross-cutting tool to create a 10×10 grid (grid area 1mm×1mm) on the surface of the heat shielding coating. After removing debris from the grid, 3M 610 tape was applied to the grid area, and the tape was quickly peeled off at a 90° angle. This process was repeated three times. The coating was rated based on the degree of peeling (5B for no peeling, 4B for minor peeling at the edges, 3B for ≤15% peeling area at the edges, 2B for 15%~35% peeling area, 1B for 35%~65% peeling area, 0B for >65% peeling area). Simultaneously, a tensile testing machine was used to test the peel adhesion between the heat shielding coating and the modified PVB substrate (tensile speed 50mm / min, room temperature 23℃). Five different locations were tested for each sample, and the average adhesion was calculated. The results are shown in Table 1.

[0088] (3) Test on the peeling rate and performance degradation rate of the heat shielding coating after thermal cycling: The thermal cycling test was conducted according to GB / T10586-2006 "Damp Heat Aging Test Method". The cycling conditions were set as follows: -40℃ constant temperature for 2 hours → room temperature transition for 5 minutes → 85℃ constant temperature for 2 hours → room temperature transition for 5 minutes, completing one cycle, for a total of 50 cycles. After cycling, the percentage of coating peeling area was calculated using visual observation and image analysis software (peeling rate = peeling area / total coating area × 100%). Simultaneously, the near-infrared blocking rate was retested according to GB / T2680, and the performance degradation rate was calculated using "(blocking rate before cycling - blocking rate after cycling) / blocking rate before cycling × 100%". The results are shown in Table 1.

[0089] (4) Transmittance and reflectance glare test: The transmittance test was conducted according to GB / T2680 "Test Methods for Solar and Optical Performance of Building Glass", with a visible light wavelength range of 380~780nm, and the average transmittance was recorded. The reflectance glare rate test was conducted according to GB / T1865-2009 "Artificial Climate Aging and Artificial Radiation Exposure of Paints and Varnishes", using a D65 standard light source, with the observation angle set at 15°, and the reflectance glare rate data was recorded. Each sample was tested 3 times, and the average value was taken. The results are shown in Table 1.

[0090] (5) Peel strength test with glass: Referring to GB / T11944-2012 "Insulating Glass", a laminate was made by laminating a full-band heat-shielding modified PVB composite film with float glass (thickness 3mm) using a lamination process (30kPa pressure reduction, temporary pressing at 100℃ for 20min, and high-pressure autoclave pressing at 1.2MPa and 140℃ for 60min). The peel strength between the full-band heat-shielding modified PVB composite film and the glass was tested using a tensile testing machine (tensile speed 50mm / min, room temperature 23℃). Each sample was tested 5 times, and the average value was taken. The results are shown in Table 1.

[0091] (6) Heat shielding coating haze test: Referring to GB / T2410-2008 "Determination of light transmittance and haze of transparent plastic", the haze value of the heat shielding coating was tested using a haze meter in an environment of room temperature 23℃ and relative humidity 50%. Five points were selected in the test area, including the center and the surrounding area of ​​the coating, and the average value was taken. The results are shown in Table 1.

[0092] (7) Dispersion stability test: The heat shield coating slurry was sealed and left for 30 days. Observe whether stratification or precipitation occurs, test the particle size distribution before and after the storage period, and calculate the particle size change rate. The results are shown in Table 1.

[0093] Table 1. Test results for each test item in Test Example 1.

[0094] As can be seen from Table 1, the full-band thermal shielding modified PVB composite film prepared by this invention exhibits excellent overall performance and outstanding characteristics in various aspects, specifically: Regarding near-infrared blocking, Examples 1-3, employing a dual-component synergistic approach of CsWO3 nanoparticles and ZnO nanoparticles, and uniformly dispersed via twin-screw mixing, achieved stable short-wave blocking rates of 88.6%-91.5% in the 780-1800 nm range and long-wave blocking rates ≥85.3% in the 1800-2500 nm range, with a full-band fluctuation range ≤1.9%, thus achieving highly efficient and stable thermal shielding across the entire wavelength range. Comparative Example 1, without the addition of ZnO nanoparticles, exhibited a near-infrared blocking rate of only 72.3% in the short and medium wavelengths and a long-wave blocking rate of 60.5%, and due to uneven dispersion of the single component, the full-band fluctuation range was also significant. The shielding efficiency was 8.6%, which could not meet the full-band shielding requirements. Comparative Example 2 used a single-screw process, which resulted in insufficient dispersion uniformity. The blocking rates for medium and short waves and long waves dropped to 85.7% and 80.3%, respectively, with a fluctuation range of 4.3%. The performance stability was significantly worse than that of Examples 1-3. Although Comparative Example 3 maintained a certain blocking efficiency due to the synergy of the two components, the lack of KH560 led to unstable bonding between the thermal shielding coating and the substrate, which indirectly affected the consistency of the blocking performance. The fluctuation range was slightly higher than that of the examples. Comparative Example 4 used a traditional deionized water-ethanol dispersion system, which had poor dispersion effect and poor near-infrared blocking performance.

[0095] Regarding coating adhesion, Examples 1-3, through high-speed mixing and twin-screw extrusion, achieved a KH560 dispersion uniformity of ≥95%, forming a stable chemical bond with the heat shielding coating. The adhesion of the heat shielding coating reached 4.7-5.3 MPa, with a cross-cut rating of 5B, and no peeling occurred. Although the adhesion of the heat shielding coating in Comparative Example 1 was close to that of the embodiments of the present invention, it lacked ZnO nanopowder and could only achieve single-band blocking, resulting in functional defects. Comparative Example 2 used a single-screw process, but the KH560 was unevenly dispersed, and the coating adhesion dropped to 3.6 MPa, with a cross-cut rating of 4B and a small amount of peeling at the edges. Comparative Example 3 did not add KH560, and the coating and substrate were only physically bonded, with an adhesion of only 1.5 MPa, a cross-cut rating of 2B, and a peeling area of ​​15-35%, exposing the reliability shortcomings of traditional physical bonding. Comparative Example 4 used a traditional deionized water-ethanol dispersion system, which had poor dispersion effect and poor coating adhesion performance.

[0096] Regarding coating peeling and performance degradation, after 50 cycles of thermal cycling (-40~85℃), Examples 1-3 showed a coating peeling rate of ≤0.8% and a performance degradation rate of ≤2.1%, demonstrating excellent weather resistance and stability. This is attributed to the uniform distribution across the entire surface resulting from the twin-screw extrusion process, with no weak areas in the film. Comparative Example 1, lacking ZnO nanopowder, exhibited insufficient coating structural stability, with a peeling rate of 3.2% and a degradation rate of 6.8%. Comparative Example 2, with its single-screw extrusion process leading to uneven dispersion, showed a peeling rate of 8.9% and a degradation rate of 9.5% after cycling, indicating significant performance degradation. Comparative Example 3, lacking the chemical bonding effect of KH560, suffered from easy coating peeling, with a peeling rate as high as 18.7% and a degradation rate of 15.3%, failing to meet long-term usage requirements. Comparative Example 4, employing a traditional deionized water-ethanol dispersion system, showed poor dispersion and exhibited poor performance in terms of coating peeling and performance degradation.

[0097] Regarding transmittance and reflective glare, the transmittance of Examples 1-3 is ≥87.8%, far exceeding the basic requirement of ≥75% for automotive windshields, and the reflective glare is ≤2.7%, with no visual interference. This is because the twin-screw process ensures uniform dispersion of nanoparticles, avoiding optical inhomogeneity caused by agglomeration; Comparative Example 1 lacks ZnO nanoparticles, resulting in slightly poorer optical consistency of the coating and a glare rate of 2.8%; Comparative Example 2's single-screw process leads to uneven particle dispersion, reducing transmittance to 87.5% and glare rate to 3.5%, which may affect the clarity of the driver's field of vision; Comparative Example 3 lacks KH560 modification, resulting in a small gap at the interface between the substrate and the coating, with a glare rate of 3.2%, and the optical experience is inferior to the embodiments of this invention; Comparative Example 4 uses a traditional deionized water-ethanol dispersion system, which has poor dispersion effect, affecting both transmittance and reflective glare.

[0098] Regarding the peel strength from glass, Examples 1-3 all exhibited peel strengths ≥60 N / m, meeting the requirements of GB / T11944 standard, demonstrating strong adhesion between the modified PVB matrix and glass. The twin-screw process ensured uniform distribution of KH560, guaranteeing sufficient bonding sites between the modified PVB matrix and glass. While Comparative Example 1 showed a peel strength of 61 N / m, its function was limited, lacking full-band shielding capability. Comparative Example 2, with its single-screw process, resulted in significant matrix thickness deviations and loose adhesion to the glass, reducing the peel strength to 52 N / m. Comparative Example 3, lacking KH560 modification, suffered from decreased matrix adhesion, resulting in a peel strength of only 38 N / m, failing to meet the safety requirements of laminated glass. Comparative Example 4 employed a traditional deionized water-ethanol dispersion system, which resulted in poor dispersion and decreased peel strength from glass.

[0099] Regarding coating haze, the coatings in Examples 1-3 had a haze of ≤0.9%, exhibiting high visual clarity without blurring or color difference issues. This is because the synergistic effect of pre-dispersion and fine dispersion in the twin-screw mixing ensures that the uniformity of nanoparticle size is ≥92%, avoiding light scattering caused by agglomeration. Comparative Example 1 lacked ZnO nanoparticles, resulting in insufficient coating density and a haze of 1.5%. Comparative Example 2's single-screw process led to uneven particle dispersion, resulting in a haze of 1.3%. Comparative Example 3 lacked KH560 modification, resulting in microbubbles at the coating-substrate interface and a haze of 1.1%, all higher than the embodiments of this invention, indicating poor optical consistency. Comparative Example 4 used a traditional deionized water-ethanol dispersion system, which resulted in poor dispersion and poor coating haze performance.

[0100] As can be seen from the above embodiments, the blocking efficiency of the 780~1800nm ​​mid-short wave near-infrared and the blocking efficiency of the 1800~2500nm long wave near-infrared of the present invention are improved by more than 22.5% and 41% respectively compared with Comparative Example 1, and the fluctuation range of the whole band is only 1 / 4 of that of Comparative Example 1, which solves the problems of insufficient long wave blocking and large performance fluctuation in the prior art.

[0101] This invention effectively enhances dispersion uniformity through twin-screw extrusion, doubling the product performance stability. The coating adhesion of Examples 1-3 is 30.6% higher than that of Comparative Example 2. The cross-cut rating, peeling rate after thermal cycling, and performance degradation rate are all far superior to those of Comparative Example 2. At the same time, the coating haze is ≤0.9%, the reflective glare rate is ≤2.7%, and the optical consistency is better, ensuring clear driving vision.

[0102] This invention utilizes epoxy silane coupling agents to modify and construct stable chemical bonds, thereby improving the reliability of the heat shield coating and lamination. The coating adhesion of Examples 1-3 is more than 3.1 times that of Comparative Example 3, the peel strength from glass is 57.9% higher than that of Comparative Example 3, and the peeling rate after thermal cycling is 95.7% lower than that of Comparative Example 3. This can solve the problem of easy peeling of traditional physical bonding and extend the service life of the product.

[0103] The composite dispersion system provided by this invention has significant advantages. The particle size change rate of the dispersion stability of Examples 1-3 is ≤1.2% after 30 days, which is far better than that of Comparative Example 4 (water-ethanol system, 8.5%). It effectively inhibits the agglomeration of nanoparticles and ensures stable heat shielding performance during long-term use. At the same time, it avoids the problem of immiscibility between 3G8 and ethanol and improves the uniformity of the coating.

[0104] The total thickness of the full-band heat-shielding modified PVB composite film of this invention strictly follows integer multiples of 0.38mm (0.38mm, 0.76mm), which meets the requirements of "weight reduction and energy consumption reduction" for new energy vehicles, takes into account both lightweighting and environmental protection, reduces weight by more than 40% compared with existing thick films, and has a light transmittance of ≥87.8%, which is higher than the standard of ≥75% for automotive windshields. The reflective glare rate is ≤2.7%, which has no visual interference. Moreover, it adopts a water-based coating system and a twin-screw low-energy consumption process, which is suitable for green production requirements.

[0105] In summary, the full-band thermal shielding modified PVB composite film provided by this invention can achieve efficient near-infrared blocking across the entire 780~2500nm band, improve coating adhesion and performance stability, and simultaneously meet the needs of lightweighting, environmental protection and industrial production, thus having broad application prospects.

[0106] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and not to limit them. Although the present invention has been described in detail with reference to preferred embodiments, those skilled in the art should understand that modifications or equivalent substitutions can still be made to the technical solutions of the present invention, and these modifications or equivalent substitutions cannot cause the modified technical solutions to deviate from the spirit and scope of the technical solutions of the present invention.

Claims

1. A full-band thermally shielding modified PVB composite film, characterized in that, The full-band heat-shielding modified PVB composite film has an asymmetric structure, including a modified PVB matrix and a heat-shielding coating covering one side of the modified PVB matrix. The modified PVB matrix comprises polyvinyl butyral and epoxy silane coupling agent. The heat shielding coating is composed of CsWO3 nanopowder, ZnO nanopowder, water-based acrylic resin, and a composite dispersion system. The composite dispersion system comprises triethylene glycol diisooctanoate, polyvinylpyrrolidone and diethylene glycol monobutyl ether; The total thickness of the full-band heat-shielding modified PVB composite film is 0.38A mm, where A is a positive integer.

2. The full-band thermal shielding modified PVB composite film according to claim 1, characterized in that, The thickness of the heat shield coating is 30~50μm.

3. The full-band thermally shielding modified PVB composite film according to claim 1, characterized in that, In the modified PVB matrix, the epoxy silane coupling agent accounts for 0.3~0.8 wt% of the mass of polyvinyl butyral; The epoxy silane coupling agent includes one or more of γ-glycidyl etheroxypropyltrimethoxysilane, γ-glycidyl etheroxypropyltriethoxysilane and β-(3,4-epoxycyclohexyl)ethyltrimethoxysilane; The polyvinyl butyral includes Kuraray Mowital® B60H, and the polyvinyl alcohol content of Kuraray Mowital® B60H is 18~20wt%.

4. The full-band thermal shielding modified PVB composite film according to claim 1, characterized in that, The heat shielding coating comprises 12-15 wt% CsWO3 nanopowder, 3-5 wt% ZnO nanopowder, 20-25 wt% waterborne acrylic resin, and 55-65 wt% composite dispersion system. Based on a total mass of 100wt% for the heat shielding coating, the composite dispersion system comprises 5-10wt% triethylene glycol diisooctanoate, 1-3wt% polyvinylpyrrolidone, and 45-55wt% diethylene glycol monobutyl ether.

5. The full-band thermally shielding modified PVB composite film according to claim 1, characterized in that, The D of the CsWO3 nanopowder 50 The particle size is 20~30nm; The D of the ZnO nanopowder 50 The particle size is 10~20nm.

6. The method for preparing the full-band heat-shielding modified PVB composite film according to any one of claims 1 to 5, characterized in that, Includes the following steps: S1. Preparation of modified PVB matrix: Polyvinyl butyral and epoxy silane coupling agent are mixed at high speed and then subjected to twin-screw extrusion and cooling to obtain modified PVB matrix. The dispersion uniformity of the epoxy silane coupling agent in the modified PVB matrix is ​​≥95%; The high-speed mixing is a stirring mixing, and the stirring speed is 1200~1500 r / min; S2. Preparation of heat shield coating slurry: CsWO3 nanopowder, ZnO nanopowder and water-based acrylic resin are premixed with a twin-screw extruder to obtain a premix. Then the premix and the composite dispersion system are ultrasonically dispersed and milled in sequence to obtain the heat shield coating slurry. The rotational speed of the twin-screw premixer is 100~150 r / min; S3. Coating and curing: The heat shielding coating slurry is coated on one side of the modified PVB substrate to obtain a wet film. Then the wet film is dried and cured in sequence to obtain the full-band heat shielding modified PVB composite film. There is no requirement for the time order of steps S1 and S2.

7. The method for preparing the full-band thermally shielding modified PVB composite film according to claim 6, characterized in that, In S1, the stirring and mixing time is 10~15 min; The temperature range of the twin-screw extrusion includes: zone 1 150~155℃, zone 2 160~165℃, zone 3 170~175℃ and die head 165~170℃; The screw speed of the twin-screw extruder is 250~300 r / min; The cooling and shaping process uses a 25-30℃ cooling roller traction method.

8. The method for preparing the full-band thermally shielding modified PVB composite film according to claim 6, characterized in that, In S2, the premixing time of the twin-screw compressor is 5-8 minutes; The ultrasonic dispersion power is 700~1000W, and the time is 25~35min; The grinding process uses zirconium beads with a diameter of 0.1~0.2mm, and the grinding time is 25~35min. The viscosity of the heat shield coating slurry is 200~300mPa·s, and the particle size uniformity is ≥92%.

9. The method for preparing the full-band thermally shielding modified PVB composite film according to claim 6, characterized in that, In S3, the coating speed is 3~4 m / min; The thickness of the wet film is 80~100μm; The drying temperature is 50~70℃, and the holding time is 12~18min; The curing temperature is 100~120℃, and the holding time is 40~50min.

10. The application of the full-band heat-shielding modified PVB composite film according to any one of claims 1 to 5, characterized in that, The full-band heat-shielding modified PVB composite film is used in automotive glass, building energy-saving glass, or windows of new energy equipment.

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